JP4595585B2 - Image processing apparatus, image processing method, program, and printing apparatus - Google Patents

Description

  The present invention relates to an image processing apparatus, an image processing method, a program, and a printing apparatus that perform image processing on image data to create print data for printing an image.

  Image output devices that output images by forming dots on various output media such as print media and liquid crystal screens are widely used as output devices for various image devices. In these image output devices, images are handled in a state of being subdivided into small areas called pixels, and dots are formed in these pixels. When dots are formed in the pixels, of course, only one state of whether or not the dots are formed can be taken from the viewpoint of each pixel. However, when viewed in an area with a certain size, it is possible to make the density of the dots formed dense and dense, and it is possible to output a multi-tone image by changing the dot formation density. is there. For example, when forming black ink dots on a printing paper, a region where dots are densely formed looks dark, and conversely, a region where dots are sparsely formed appears bright. In addition, when bright dots are formed on a liquid crystal screen, a region where dots are densely formed looks bright and a region where sparsely formed dots appear dark. Accordingly, if the dot formation density is appropriately controlled, a multi-tone image can be output. As described above, data for controlling dot formation so as to obtain an appropriate formation density is generated by performing predetermined image processing on an image to be output.

  In recent years, these image output apparatuses have been required to have high output image quality and large images. It is effective to divide an image into finer pixels for the demand for higher image quality. If the pixels are made smaller, the dots formed on the pixels become inconspicuous and the image quality can be improved. In addition, a request for a large image is handled by increasing the number of pixels. Of course, the output image can also be enlarged by increasing the size of each pixel, but this leads to a decrease in image quality, so it is effective to increase the number of pixels in response to a demand for larger size. It is.

However, when the number of pixels constituting the image increases, it takes time for image processing, and it becomes difficult to output the image quickly. Therefore, a technique that enables image processing to be executed quickly has been proposed (Patent Document 1).
JP 2002-185789 A

However, even if the image processing is performed quickly, if the transfer of the image data or the transfer of the processed image data takes time, the effect of speeding up the output of the image is naturally limited. .
In recent years, there has been a demand for supplying image data captured by a digital camera or the like directly to an image output apparatus such as a printing apparatus and outputting the image immediately. In such a case, image processing cannot be performed using an image processing apparatus having high processing capability such as a so-called personal computer. Therefore, it is necessary to perform simple image processing so that it can be executed by either an image capturing apparatus such as a digital camera, an image output apparatus, or both.

  The present invention has been made in view of such circumstances, and an object of the present invention is to realize high-speed image processing and data transfer while suppressing deterioration in image quality.

The main invention for achieving the object is as follows:
(A) Based on the classification number classified according to the position of each pixel constituting the image represented by the image data and the gradation value of each pixel constituting the image represented by the image data A multi-value processing unit that generates multi-value gradation value data that has been multi-valued according to the resolution of the image;
(B) A dot number data conversion table for converting the multi-value gradation value data into dot number data representing the number of dots to be formed and the dot size, and the order in which the dots to be formed are to be formed. Based on the set dot formation order data, generate dot data in which the positions and dot sizes of the dots to be formed are determined, and associate the pixels in the dot data with the pixels constituting the image data A dot formation data generator for generating dot formation data,
With
The dot formation data generation unit is an image processing device that generates the dot formation data by cutting out a predetermined number of pixels in the dot data from the dot data according to the resolution of the dot formation data. is there.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

=== Summary of disclosure ===
At least the following matters will become apparent from the description of the present specification and the accompanying drawings.

(A) A plurality of encoded data generated by encoding the pixel data of the first image data is decoded to generate pixel data of at least one pixel for each encoded data, and the second image data A decoder that outputs
(B) The decoder sets pixel data of pixels arranged along a moving direction of a nozzle that discharges liquid based on the second image data at predetermined intervals along a direction intersecting the moving direction. A decoding controller that indicates an order of the encoded data to be decoded by the decoder;
An image processing apparatus comprising (C).
In such an image processing apparatus, it is possible to smoothly decode each of a plurality of encoded data generated by encoding pixel data of the first image data and output the second image data. it can.

  In such an image processing device, the decode controller is a pixel in which the pixel data is generated per one piece of the encoded data by the decoding process of the decoder and is arranged along the intersecting direction. The order of the encoded data to be decoded by the decoder may be instructed based on the number and the predetermined interval. Based on the number of pixels and a predetermined interval, the decoding controller can instruct the order of the encoded data to be decoded by the decoder, so that the decoding process can be performed smoothly.

  In this image processing apparatus, there may be a plurality of the nozzles along the intersecting direction, and the predetermined interval may be set corresponding to the interval of the nozzles. Since the predetermined interval is set corresponding to the nozzle interval in this way, the decoding process can be performed smoothly.

  In the image processing apparatus, the decode controller determines the order of the encoded data to be decoded by the decoder based on the formation order of dots formed on the medium by the liquid ejected from the nozzle. You may instruct. Thus, based on the dot formation order, the decoding controller can instruct the order of the encoded data to be decoded by the decoder, so that the decoding process can be performed smoothly.

  In addition, such an image processing apparatus may include a memory that stores the plurality of encoded data. If such a memory is provided, processing can be performed smoothly.

  The image processing apparatus further includes an encoder that encodes pixel data of the first image data to generate a plurality of encoded data, and the decoder includes the plurality of encoded data generated by the encoding. Data may be decoded. If such an encoder is provided, a plurality of encoded data can be generated by encoding the pixel data of the first image data.

  Further, in such an image processing apparatus, as the encoder, based on the first image data, the gradation value of each pixel constituting the first image represented by the first image data, A multi-value processing unit that generates multi-value gradation value data as the encoded data by performing multi-value processing according to the resolution of the second image represented by the second image data may be provided. If such a multi-value processor is provided as an encoder, the tone value of each pixel constituting the first image represented by the first image data can be multi-valued.

  The image processing apparatus further includes a multi-value conversion table in which the gradation value and the multi-value gradation value data are associated with each other, and the multi-value conversion processing unit includes the multi-value conversion table. The multi-value gradation value data may be generated by referring to it. If such a multi-value conversion table is provided, multi-value gradation value data can be easily obtained from gradation values.

  Further, in such an image processing device, the multi-value quantization processing unit sets the gradation value for each color of each pixel constituting the first image based on the first image data. The multi-value gradation value data may be generated by multi-value processing according to the resolution of the second image. In this way, the multi-value processing is performed by the multi-value processing unit according to the position of the pixel corresponding to the gradation value, so that dot formation data of the second image with higher image quality can be generated. The image quality of the second image can be improved.

  In the image processing apparatus, the multi-value processing unit multi-values the gradation value according to the position of the pixel corresponding to the gradation value, and performs the multi-value gradation value data. May be generated. In this way, multi-value processing is performed by the multi-value processing unit according to the position of the pixel corresponding to the gradation value, so that dot formation data with higher image quality can be generated, and the image quality of the second image Improvements can be made.

  In the image processing apparatus, the multi-value gradation value data may be generated by the multi-value processor as data of a predetermined number of bits. As described above, the multi-value gradation value data is generated as data having a predetermined number of bits, so that the data amount of the multi-value gradation value data generated by the multi-value processing unit is related to the resolution of the second image. Can be kept constant.

  In the image processing apparatus, as the decoder, the multi-value gradation value data generated by the multi-value processor is converted into dot number data representing the number of dots, and the dot number Based on the data, the presence or absence of dot formation is individually determined for one or more pixels, and at least some of the one or more pixels for which the presence or absence of dot formation is determined constitute the second image As the pixel to be processed, a dot formation data generation unit that generates the dot formation data of the second image having the resolution as the second image data may be provided. If such a dot formation data generation unit is provided as a decoder, it is possible to generate dot formation data as the second image data based on the multi-value gradation value data generated by the multi-value processing unit. .

  The image processing apparatus further includes a dot number data conversion table in which the multi-value gradation value data and the dot number data are associated with each other, and the dot formation data generation unit includes the dot number data. The multi-value gradation value data may be converted into the dot number data by referring to a conversion table. By providing such a dot number data conversion table, dot number data can be easily obtained from multi-value gradation value data.

  In the image processing apparatus, the dot formation data generation unit may determine whether or not to form dots individually for a predetermined number of pixels based on the dot number data. Thus, if the presence or absence of dot formation is determined for a predetermined number of pixels, the processing can be performed smoothly.

  In such an image processing apparatus, the dot number data may include data relating to the dot size in addition to the number of dots. In this way, if data relating to dot size is included, it is possible to determine whether or not to form dots having different sizes.

  Further, in such an image processing apparatus, the dot formation data generation unit individually sets the dot formation data for the one or more pixels based on dot formation order data indicating the dot formation order in addition to the dot number data. The presence or absence of formation may be determined. In this way, if the presence or absence of dot formation is individually determined for one or more pixels based on the dot formation order data, the processing can be performed smoothly.

  In this image processing apparatus, the dot forming data generation unit uses the one or more pixels determined to be dot-formed or not as pixels constituting the second image. The number of pixels may be different depending on the resolution of the second image. As described above, the number of pixels used as the pixels constituting the second image among the one or more pixels differs according to the resolution of the second image, so that the second image having different resolutions. The dot formation data can be easily generated.

  Further, in such an image processing apparatus, the dot forming data generation unit is used as a pixel constituting the second image from the one or more pixels for which the presence or absence of the dot formation is determined. The position of the pixel may be different depending on the position of the pixel corresponding to the gradation value subjected to the multi-value processing when the multi-value gradation value data is generated. As described above, the position of the pixel used as the pixel constituting the second image among the one or more pixels corresponds to the gradation value subjected to the multi-value processing when the multi-value gradation value data is generated. By changing according to the position of the pixel, the dot formation data of the second image can be generated smoothly.

(A) A plurality of encoded data generated by encoding the pixel data of the first image data is decoded to generate pixel data of at least one pixel for each encoded data, and the second image data A decoder that outputs
(B) The decoder sets pixel data of pixels arranged along a moving direction of a nozzle that discharges liquid based on the second image data at predetermined intervals along a direction intersecting the moving direction. A decoding controller that indicates an order of the encoded data to be decoded by the decoder;
(C)
(D) The decode controller includes the number of pixels arranged along the intersecting direction and the predetermined number of pixels for which the pixel data is generated per encoded data by the decoding process of the decoder, Instructing the order of the encoded data to be decoded by the decoder based on the interval,
(E) There are a plurality of the nozzles along the intersecting direction, and the predetermined interval is set corresponding to the interval of the nozzles,
(F) The decode controller instructs the order of the encode data to be decoded by the decoder based on the formation order of dots formed on the medium by the liquid ejected from the nozzle,
(G) comprising a memory for storing the plurality of encoded data;
(H) an encoder that encodes pixel data of the first image data to generate a plurality of encoded data, and the decoder decodes the plurality of encoded data generated by the encoding;
(I) As the encoder, based on the first image data, the gradation value of each pixel constituting the first image represented by the first image data is represented by the second image data. A multi-value processing unit that performs multi-value processing according to the resolution of the second image to be generated and generates multi-value gradation value data as the encoded data,
(J) a multi-value conversion table in which the gradation value and the multi-value gradation value data are associated with each other, and the multi-value conversion processing unit refers to the multi-value conversion table to refer to the multi-value conversion table. Generate key value data,
(K) Based on the first image data, the multi-value processing unit sets the gradation value for each color of each pixel constituting the first image according to the resolution of the second image. Multi-value processing is performed to generate the multi-value gradation value data,
(L) The multi-value processing unit generates the multi-value gradation value data by performing multi-value processing on the gradation value according to the position of a pixel corresponding to the gradation value,
(M) The multi-value gradation value data is generated by the multi-value processor as data of a predetermined number of bits,
(N) As the decoder, the multi-value gradation value data generated by the multi-value processor is converted into dot number data representing the number of dots, and one or more pixels are based on the dot number data. And determining whether or not dot formation is performed individually, and setting at least a part of the one or more pixels determined to have dot formation or not as pixels constituting the second image. A dot formation data generation unit that generates dot formation data of a second image as the second image data;
(O) a dot number data conversion table in which the multi-value gradation value data and the dot number data are associated with each other, and the dot formation data generation unit refers to the dot number data conversion table; Converting the multi-value gradation value data into the dot number data;
(P) The dot formation data generation unit individually determines the presence or absence of dot formation for a predetermined number of pixels based on the dot number data,
(Q) In addition to the number of dots, the dot number data includes data related to the dot size,
(R) The dot formation data generation unit determines whether or not to form dots individually for the one or more pixels based on dot formation order data indicating the dot formation order in addition to the dot number data.
(S) The number of pixels used as the pixels constituting the second image among the one or more pixels for which the presence or absence of the dot formation is determined by the dot formation data generation unit is the second number. Depending on the resolution of the image,
(T) A position of a pixel used as a pixel constituting the second image among the one or more pixels determined by the dot formation data generation unit to determine whether or not the dot is formed is the multivalued value. Depending on the position of the pixel corresponding to the gradation value subjected to multi-value processing when generating gradation value data,
(U) An image processing apparatus.

A plurality of encoded data generated by encoding the pixel data of the first image data is decoded, pixel data of at least one pixel is generated for each encoded data, and the second image data is output. Steps,
In the step, when outputting the second image data, the pixel data of the pixels arranged along the moving direction of the nozzle that discharges the liquid based on the second image data intersects the moving direction. And a step of instructing a decoding order of the encoded data in order to generate the data at predetermined intervals along the direction of the image processing.

A plurality of encoded data generated by encoding the pixel data of the first image data is decoded, pixel data of at least one pixel is generated for each encoded data, and the second image data is output. Steps,
In the step, when outputting the second image data, the pixel data of the pixels arranged along the moving direction of the nozzle that ejects the liquid based on the second image data intersects the moving direction. And a step of instructing a decoding order of the encoded data so as to be generated at predetermined intervals along the direction of the encoding.

(A) A plurality of encoded data generated by encoding the pixel data of the first image data is decoded to generate pixel data of at least one pixel for each encoded data, and the second image data A decoder that outputs
(B) The decoder sets pixel data of pixels arranged along a moving direction of a nozzle that discharges liquid based on the second image data at predetermined intervals along a direction intersecting the moving direction. A decoding controller that indicates an order of the encoded data to be decoded by the decoder;
(C) a printing unit that performs printing on a medium based on the second image data output from the decoder;
A printing apparatus comprising (D).

  Such a printing apparatus may include an image reading unit that reads an image from a document and generates the image data. The read image data can be smoothly converted to the second image data as the first image data, and the image can be printed.

=== Overview of Image Processing Apparatus ===
An embodiment of an image processing apparatus and the like according to the present invention will be described. Here, a case where the image processing apparatus according to the present invention is applied to a printing apparatus will be described as an example. Furthermore, here, as an embodiment of a printing apparatus according to the present invention, a case where the present invention is applied to an inkjet printer 1 equipped with a scanner will be described as an example.

  1 to 6 describe the outline of the ink jet printer 1. FIG. 1 is a perspective view for explaining the appearance of the ink jet printer 1. FIG. 2 is a perspective view illustrating an outline of the scanner unit 10 of the inkjet printer 1. FIG. 3 is a perspective view illustrating an outline of the printer unit 30 of the inkjet printer 1. FIG. 4 is an explanatory diagram schematically illustrating the internal configuration of the ink jet printer 1. FIG. 5 is a cross-sectional view illustrating the transport mechanism of the printer unit 30 of the inkjet printer 1. FIG. 6 is a plan view for explaining the operation panel 2 of the ink jet printer 1.

  This inkjet printer 1 with a scanner has a scanner function for reading an image from a document and generating image data, and a printer function for printing on various media such as printing paper based on print data sent from a host computer (not shown). And a scanner / printer / copy composite apparatus (hereinafter also referred to as an SPC composite apparatus) provided with a local copy function for copying an image read from a document on a medium. As shown in FIG. 1, the SPC multifunction apparatus 1 includes a scanner unit 10 for reading an image from a document 5 at an upper portion thereof, and prints on a medium S such as a printing paper at a lower portion of the SPC multifunction apparatus 1. A printer unit 30 is provided. An operation panel 2 is provided on the front surface of the SPC multifunction apparatus 1.

  As shown in FIG. 2, the scanner unit 10 includes a document table 11 provided with a glass plate on which the document 5 is set, and a document table cover 12 that covers the document table 11 from above. The document table cover 12 is rotatably attached to the rear end portion of the SPC multifunction apparatus 1 so as to open and close the upper surface portion of the document table 11. The scanner unit 10 corresponds to an “image reading unit”.

  On the other hand, as shown in FIG. 3, the printer unit 30 is configured such that the inside of the printer unit 30 is opened to the outside through the opening 32 by lifting the scanner unit 10 upward. That is, the scanner unit 10 is rotatably mounted on the rear part of the SPC multifunction apparatus 1 via the hinge unit 34. When the scanner unit 10 is lifted upward, the opening 32 leading to the inside of the printer unit 30 is opened. Inside the printer unit 30, a carriage 41 for mounting an ink cartridge is disposed. By opening the inside of the printer unit 30 in this way, maintenance work such as replacement of an ink cartridge, error handling such as a paper jam, and the like can be easily performed through the opening 32.

  The printer unit 30 includes a paper feeding unit 4 on which a medium S such as printing paper is set and sequentially supplies the medium S to the back of the SPC multifunction apparatus 1. The printer unit 30 includes a paper discharge unit 3 that discharges the printed medium S at the front of the SPC multifunction apparatus 1. The paper feed unit 4 includes a paper feed tray 8. A medium such as printing paper is set in the paper feed tray 8. The paper discharge unit 3 includes a paper discharge tray 7 and receives the medium S that has been printed and discharged. The medium S set in the paper feeding unit 4 may be not only single-sheet printing paper such as cut paper but also continuous printing paper such as roll paper. A corresponding structure may be provided.

=== Internal Mechanism of Scanner Unit 10 and Printer Unit 30 ===
FIG. 4 shows the internal mechanism of the scanner unit 10 and the printer unit 30.

<Scanner part>
As shown in the upper part of the figure, the scanner unit 10 has a scanner carriage 60 below the document table 11 and an arrow A in the figure while keeping the scanner carriage 60 at a predetermined distance from the document table 11. A driving mechanism 62 that moves in parallel along the direction and a guide 64 that supports the scanner carriage 60 and guides its movement are provided.

The scanner carriage 60 includes an exposure lamp 66 as a light source for irradiating light to the document 5 via the document table 11, a plurality of mirrors 68 for guiding reflected light reflected from the document 5, and a mirror 68. A lens 70 for collecting the guided reflected light and a CCD sensor 72 for receiving the reflected light collected by the lens 70 are mounted.
The CCD sensor 72 includes three linear sensors (not shown) configured by arranging photodiodes that convert optical signals into electric signals in a line. These three linear sensors are arranged in parallel with a space therebetween, and are provided with filters of three colors of R (red), G (green), and B (blue), respectively. Each linear sensor detects light of a component corresponding to the color of each filter from the reflected light, and outputs the detection result to the control unit 50.
The drive mechanism 62 includes a timing belt 74 connected to the scanner carriage 60, a pair of pulleys 75 and 76 around which the timing belt 74 is stretched, and a drive motor 77 that rotationally drives one pulley 75. I have. The drive motor 77 is driven and controlled by a control signal from the control unit 50.

<Printer section>
On the other hand, the printer unit 30 holds the printer carriage 41, the head 21 mounted on the printer carriage 41, and the printer carriage 41 at a predetermined distance from the medium S, as shown in the lower part of FIG. However, a drive mechanism 24 that moves relatively parallel to each other and a transport mechanism 36 that transports the medium S along a direction orthogonal to the moving direction of the printer carriage 41 are provided.

The printer carriage 41 is provided with a cartridge mounting portion, and an ink cartridge containing black (K), cyan (C), magenta (M), yellow (Y) or the like ink is stored in the cartridge mounting portion. Installed.
The head 21 ejects ink of each color supplied from the ink cartridge toward the medium S to form dots on the medium S, and forms an image on the medium S to perform printing. The ink ejection mechanism of the head 21 will be described in detail later.

  The drive mechanism 24 includes a timing belt 45 connected to the printer carriage 41, a pulley 44 meshed with the timing belt 45, a carriage motor 42 (hereinafter also referred to as a CR motor) that rotationally drives the pulley 44, A guide rail 46 for guiding the movement of the printer carriage 41, a linear encoder code plate 51 as a linear encoder for detecting the position of the printer carriage 41, and a detection unit 52 for reading the linear encoder code plate 51 are provided. Yes. The drive mechanism 24 drives the carriage motor 42 to rotate the timing belt 45 via the pulley 44. As a result, the printer carriage 41 moves relative to the medium S along the guide rail 46. The carriage motor 42 is driven and controlled by a control signal from the control unit 50.

The transport mechanism 36 includes a platen 14, a transport roller 17 </ b> A, a transport motor 15 that rotationally drives the transport roller 17 </ b> A (hereinafter also referred to as a PF motor), and paper that detects whether the medium S has reached a predetermined position. A detection sensor 53 and a rotary encoder 56 for detecting the rotation amount of the transport roller 17A are provided. The platen 14 is disposed to face the head 21. When the transport motor 15 is driven, the transport roller 17 </ b> A rotates and the medium S is transported on the platen 14. The conveyance motor 15 is driven and controlled by a control signal from the control unit 50.
At the time of printing, the medium S is intermittently transported by a predetermined transport amount by the transport roller 17A, and the printer carriage 41 extends in a direction intersecting the transport direction by the transport roller 17A between the intermittent transports. Printing is performed by ejecting ink from the head 21 toward the medium S while moving.

<Transport mechanism>
A transport mechanism of the printer unit 30 will be described. As shown in FIG. 5, the transport mechanism includes a paper feed roller 13, a paper detection sensor 53, a transport roller 17A, a paper discharge roller 17B, a platen 14, and free rollers 18A and 18B.

The medium S to be printed is set in the paper feed tray 8 of the paper feed unit 4. The medium S set in the paper feed tray 8 is transported along the direction of arrow A in the drawing by the paper feed roller 13 having a substantially D-shaped cross section, and is sent into the ink jet printer 1. The medium S sent to the inside of the ink jet printer 1 comes into contact with the paper detection sensor 53. The paper detection sensor 53 is installed between the paper feed roller 13 and the transport roller 17A, and detects the medium S fed by the paper feed roller 13.
The medium S detected by the paper detection sensor 53 is sequentially transported to the platen 14 on which printing is performed by the transport roller 17A. A free roller 18A is provided at a position facing the conveying roller 17A. The medium S is smoothly transported by sandwiching the medium S between the free roller 18A and the transport roller 17A.
The medium S sent to the platen 14 is sequentially printed by the ink ejected from the head 21. The platen 14 is provided to face the head 21 and supports the medium S to be printed from below.
The medium S on which printing has been performed is sequentially discharged out of the printer unit 30 by the paper discharge roller 17B. The paper discharge roller 17B is driven in synchronism with the transport motor 15, and sandwiches the medium S with the free roller 18B provided facing the paper discharge roller 17B. To discharge.

=== Operation panel ===
FIG. 6 shows the operation panel 2 of the SPC multifunction apparatus 1.
The operation panel 2 includes a liquid crystal display 80 at substantially the center thereof. The liquid crystal display 80 can display characters and images. The display content of the liquid crystal display 80 changes according to the setting item, the setting state, the operation state, and the like.

  On the left side of the liquid crystal display 80, a notification lamp 81, a power button 82, various setting buttons 83, mode buttons 84, 85, 86, 87, and a paper supply / discharge button 88 are provided. The notification lamp 81 is a red LED and lights up when an error occurs to notify the user of the occurrence of the error. The power button 82 is a button for turning on / off the power of the SPC multifunction apparatus 1. The various setting buttons 83 are buttons for displaying on the liquid crystal display 80 a screen for performing various settings of the SPC multifunction apparatus 1. The mode buttons 84, 85, 86, and 87 are buttons for setting the mode of the SPC multifunction apparatus 1, respectively. Here, a copy mode button 84, a memory card print mode button 85, a film print mode button 86, and a scan mode button 87 are provided as mode buttons. Here, for example, when the copy mode button 84 is pressed, a screen for inputting setting conditions such as the number of copies, magnification, paper type, paper size, copy quality, and copy mode is displayed on the liquid crystal display 80. The paper supply / discharge button 88 is pressed when the medium S is fed to the SPC multifunction apparatus 1 or when the medium S in the SPC multifunction apparatus 1 is ejected.

  On the right side of the liquid crystal display 80, there are an OK button 89A, a cancel button 89B, a save button 89C, a color copy button 89D, a monochrome copy button 89E, a stop button 89F, a cross button 89G, and a menu button 89H. Is provided. When the OK button 89A is pressed, the setting conditions are determined based on the contents displayed on the liquid crystal display 80. When the cancel button 89B is pressed, the setting conditions are cleared and each setting item is changed to a default value. When the save button 89C is continuously pressed for 3 seconds or more, the set value is stored. When the save button 89C is pressed for 3 seconds or less, the stored setting value is read and the setting condition is displayed on the liquid crystal display 80. The color copy button 89D is a button for starting color copy. The monochrome copy button 89E is a button for starting monochrome copy. The stop button 89F is a button for stopping the copy operation once started. The cross button 89G can be selectively pressed at the four positions on the top, bottom, left and right, and one button performs four functions (up button, down button, left button, and right button functions). Menu button 89 </ b> H switches setting items displayed on liquid crystal display 80.

=== Head ===
<Configuration of head>
FIG. 7A is a diagram illustrating an arrangement of ink nozzles provided on the lower surface of the head 21. On the lower surface of the head 21, as shown in the figure, nozzles comprising a plurality of nozzles # 1 to # 180 for each color of yellow (Y), magenta (M), cyan (C), and black (K). A row, that is, a cyan nozzle row 211C, a magenta nozzle row 211M, a yellow nozzle row 211Y, and a black nozzle row 211K are provided.

  The nozzles # 1 to # 180 (corresponding to “liquid ejection nozzles”) of the nozzle rows 211C, 211M, 211Y, and 211K are spaced from each other along a predetermined direction (here, the transport direction of the medium S). Are arranged in a straight line. The interval between the nozzles # 1 to # 180 (nozzle interval) is set to “k · D”. Here, “D” is a minimum dot pitch in the transport direction (that is, an interval at a maximum resolution of dots formed on the medium S). “K” is an integer of 1 or more. For example, when the nozzle pitch is 120 dpi (1/120 inch) and the dot pitch in the transport direction is 360 dpi (1/360 inch), k = 3. The nozzle rows 211C, 211M, 211Y, and 211K are arranged in parallel with a space therebetween along the moving direction (scanning direction) of the head 21. Each nozzle # 1 to # 180 is provided with a piezo element (not shown) as a drive element for ejecting ink droplets.

  When a voltage having a predetermined time width is applied between the electrodes provided at both ends of the piezoelectric element, the piezoelectric element expands according to the voltage application time and deforms the side wall of the ink flow path. As a result, the volume of the ink flow path contracts in accordance with the expansion and contraction of the piezo element, and the ink corresponding to this contraction becomes ink droplets, and each nozzle # 1 of each color nozzle row 211C, 211M, 211Y, 211K. It is discharged from ~ # 180.

<Drive circuit>
FIG. 7B shows the drive circuit 220 for each nozzle # 1 to # 180. The drive circuit 220 includes an original drive signal generator 221 and a plurality of mask circuits 222 as shown in FIG. The original drive signal generator 221 generates an original drive signal ODRV that is used in common by the nozzles # 1 to # 180. The original drive signal ODRV is divided into two pulses, a first pulse W1 and a second pulse W2, within the main scanning period for one pixel (within the time during which the carriage 41 crosses one pixel interval), as shown in the lower part of the figure. A signal including a pulse. The original drive signal ODRV generated by the original drive signal generator 221 is output to each mask circuit 222.

  The mask circuit 222 is provided corresponding to a plurality of piezo elements that drive the nozzles # 1 to # 180 of the head 21, respectively. Each mask circuit 222 receives the original drive signal ODRV from the original drive signal generator 221 and the print signal PRT (i). The print signal PRT (i) is pixel data corresponding to a pixel, and is a binary signal having 2-bit information for one pixel. Each bit corresponds to the first pulse W1 and the second pulse W2, respectively. The mask circuit 222 is a gate for blocking or passing the original drive signal ODRV in accordance with the level of the print signal PRT (i). That is, when the print signal PRT (i) is at level “0”, the pulse of the original drive signal ODRV is cut off, while when the print signal PRT (i) is at level “1”, the corresponding pulse of the original drive signal ODRV is output. It passes as it is and is output as an actual drive signal DRV toward the piezoelectric elements of the nozzles # 1 to # 180. The piezo elements of the nozzles # 1 to # 180 are driven based on the actual drive signal DRV from the mask circuit 222 to discharge ink.

<Each signal waveform>
FIG. 7C is a timing chart of the original drive signal ODRV, the print signal PRT (i), and the actual drive signal DRV (i) showing the operation of the original drive signal generator 221. As shown in the figure, the original drive signal ODRV sequentially generates a first pulse W1 and a second pulse W2 in each pixel section T1, T2, T3, T4. Note that the pixel section has the same meaning as the movement section of the carriage 41 for one pixel.

  Here, when the print signal PRT (i) corresponds to the 2-bit pixel data “10”, only the first pulse W1 is output in the first half of one pixel section. Thereby, small ink droplets are ejected from the nozzles # 1 to # 180, and a small dot (small dot) is formed on the medium S. When the print signal PRT (i) corresponds to 2-bit pixel data “01”, only the second pulse W2 is output in the second half of one pixel interval. As a result, medium size ink droplets are ejected from the nozzles # 1 to # 180, and medium size dots (medium dots) are formed on the medium S. When the print signal PRT (i) corresponds to the 2-bit pixel data “11”, the first pulse W1 and the second pulse W2 are output in one pixel section. As a result, large-sized ink droplets are ejected from the nozzles # 1 to # 180, and a large-sized dot (large dot) is formed on the medium S. As described above, the actual drive signal DRV (i) in one pixel section is shaped to have three different waveforms according to three different values of the print signal PRT (i), and is based on these signals. The head 21 can form dots of three types of sizes and can adjust the amount of ink ejected in the pixel section. Further, when the print signal PRT (i) corresponds to the 2-bit pixel data “00” as in the pixel section T4, ink droplets are not ejected from the nozzles # 1 to # 180, and the medium has dot dots. Will not be formed.

  In the inkjet printer 1 according to the present embodiment, such a drive circuit 220 for the nozzles # 1 to # 180 is provided for each of the nozzle rows 211C, 211M, 211Y, 211K, that is, yellow (Y), magenta (M), cyan. (C) and black (K) are provided individually for each color, and the piezo elements are driven individually for each nozzle # 1 to 180 of each nozzle row 211C, 211M, 211Y, 211K. Yes.

=== Printing operation ===
Next, the printing operation of the above-described ink jet printer 1 will be described. Here, “bidirectional printing” will be described as an example. FIG. 8 is a flowchart showing an example of the processing procedure of the printing operation of the SPC multifunction apparatus 1. Here, the printing operation is performed based on information from sensors such as the linear encoder (the linear encoder code plate 51 and the detection unit 52), the rotary encoder 56, and the paper detection sensor 53 according to the program by the control unit 50. 15, the carriage motor 42, the drive circuit 220 of the head 21, and the like.

  When executing the printing process, the control unit 50 first performs a sheet feeding process (S102). The paper feed process is a process of supplying the medium S to be printed into the ink jet printer 1 and transporting it to a print start position (also referred to as a cue position). The control unit 50 rotates the paper feed roller 13 to send the medium S to be printed to the transport roller 17A. The controller 50 rotates the transport roller 17A to position the medium S sent from the paper feed roller 13 at the print start position (near the upper part of the platen 14).

  Next, the control unit 50 drives the carriage motor 42 to move the carriage 41 relative to the medium S to execute a printing process for printing on the medium S. Here, first, forward printing is performed to eject ink from the head 21 while moving the carriage 41 in one direction along the guide rail 46 (S104). The control unit 50 drives the carriage motor 42 to move the carriage 41 and drives the drive circuit 220 of the head 21 to drive the nozzles # 1 to # 180 of the nozzle rows 211C, 211M, 211Y, and 211K of the head 21. Ink is discharged from the nozzle. The ink ejected from the head 21 reaches the medium S and is formed as dots on the medium S.

  After printing is performed in this manner, the control unit 50 then executes a transport process for transporting the medium S by a predetermined amount (S106). Here, the control unit 50 drives the transport motor 15 to rotate the transport roller 17 </ b> A, and transports the medium S by a predetermined amount in the transport direction relative to the head 21. By this carrying process, the head 21 can print in an area different from the previously printed area.

  After carrying out the carrying process in this way, the control unit 50 determines whether or not to discharge the paper (S108). Here, if there is no other data to be printed on the medium S being printed, the control unit 50 executes a paper discharge process (S116). On the other hand, if there is other data to be printed on the medium S being printed, the control unit 50 performs the return pass printing without performing the paper discharge process (S110). In this backward printing, printing is performed by moving the carriage 41 along the guide rail 46 in the direction opposite to the previous forward printing. Here again, the controller 50 drives the carriage motor 42 to rotate in the opposite direction to move the carriage 41 and drives the drive circuit 220 of the head 21 to drive the nozzle rows 211C, 211M, 211Y, 211K of the head. Ink is ejected from each of the nozzles # 1 to # 180 for printing.

  After performing the return pass printing, a carrying process is executed (S112), and then a paper discharge determination is made (S114). Here, if there is other data to be printed on the medium S being printed, the paper discharge process is not performed, the process returns to step S104, and the forward printing is executed again (S104). On the other hand, if there is no other data to be printed on the medium S being printed, a paper discharge process is executed (S116).

  After the paper discharge process is performed, next, a print end determination is performed to determine whether or not to end printing (S118). Here, it is checked whether there is a medium S to be printed next. If there is a medium S to be printed next, the process returns to step S102, the paper feed process is executed again, and printing is started. On the other hand, if there is no medium S to be printed next, the printing process is terminated.

=== Configuration and Processing of Control Unit 50 ===
The configuration and processing of the control unit 50 will be described below. Here, the control unit 50 of the present embodiment will be described in comparison with the configuration and processing of the conventional control unit 49. First, the configuration and processing of the conventional control unit 49 will be described.

<Conventional configuration>
(A) Outline of Configuration FIG. 9 is a block configuration diagram showing a configuration of a conventional control unit 49. The conventional control unit 49 includes a CPU 90 that controls the entire SPC multifunction apparatus 1, a memory 92 that stores a control program, an ASIC 94 that controls each of the scanner function, print function, and local copy function, and the CPU 90. The SDRAM 96 capable of directly reading and writing data and the operation panel 2 as input means are connected by a CPU bus 98. The ASIC 94 includes a scanner unit 10, a head unit 100, and an ASIC SDRAM 102 that can read and write data from the ASIC 94, and an SDRAM controller 103 that controls the ASIC SDRAM 102. The control unit 49 is a control unit (controller) for performing various controls of the SPC multifunction apparatus 1.

  The ASIC 94 includes a scanner control unit 104, a resizing unit 106, a binarization processing unit 108, an interlace processing unit 110, an image buffer unit 112, a bus controller 114, a head control unit 116, and an external host computer 140. And a USB interface 118 as input / output means, and drivers (not shown) such as motors and lamps included in the scanner unit 10 and the printer unit 30.

  The ASIC SDRAM 102 is provided with a line buffer 120, a resize buffer 122, an interlace buffer 124, and image buffers 126 and 127, respectively. Between the ASIC 94 and the SDRAM controller 103 (ASIC SDRAM 102), so-called burst transfer is performed in which the data transfer unit is 64 bits in order to increase the data transfer speed. Each unit 104, 106, 108, 110, 112, 114 and the SDRAM controller 103 in the ASIC 94 are connected via a local bus 128.

  The scanner control unit 104 controls an exposure lamp 66, a CCD sensor 72, a drive motor 77 for the scanner carriage 60, and the like included in the scanner unit 10. The scanner control unit 104 has a function of sending image data read via the CCD sensor 72. Here, an RGB image composed of three colors of R (red), G (green), and B (blue) is transmitted. The scanner control unit 104 temporarily stores image data read from the document 5 in a line buffer 120 allocated to the ASIC SDRAM 102. The image data stored in the line buffer 120 is subjected to an interline correction process. The inter-line correction process is a process for correcting a deviation of the reading position between the R, G, and B linear sensors that is structurally generated in the scanner unit 10. That is, the CCD sensor 72 included in the scanner unit 10 is a color sensor, and includes a linear sensor for each line for each of three colors of R (red), G (green), and B (blue). Since these three linear sensors are arranged in parallel to the moving direction of the scanner carriage 60, the reflected light irradiated on the same line of the document 5 cannot be received simultaneously. That is, when reflected light irradiated on the same line of the document 5 is received by each linear sensor, a time shift occurs. For this reason, it is a process for synchronizing the data sent with a delay corresponding to the arrangement of the linear sensors. The scanner control unit 104 outputs the image data subjected to such inter-line correction processing as multi-gradation RGB image data (for example, 256 gradation RGB image data). Here, the scanner control unit 104 outputs image data of a predetermined resolution corresponding to the reading resolution of the scanner unit 10, for example, 360 dpi (horizontal) × 360 dpi (vertical).

  The resizing unit 106 has a function of receiving image data of a predetermined size, changing the size of the image data, and sending the resized image data. Here, the size of the image data is the number of vertical and horizontal pixels of the image. The image is large if the number of vertical and horizontal pixels is large, and the image is small if the number of vertical and horizontal pixels is small. However, the size of the actually printed image varies depending on the print resolution even if the number of pixels is large. For example, even if the number of pixels is the same, the image data of 200 dpi × 200 dpi is larger than the image data of 1440 dpi × 720 dpi. That is, changing the size of image data also means changing the resolution.

  The binarization processing unit 108 performs so-called halftone processing for converting the transmitted multi-gradation RGB image data into CMYK binary data (or 2-bit data). At this time, the binarization processing unit 108 converts the multi-gradation RGB image data into CMYK binary data (or 2-bit data) based on the lookup table 136 (LUT) stored in the ASIC SDRAM 102. Convert to The CMYK binary data (or 2-bit data) generated by the conversion by the binarization processing unit 108 in this way is transmitted to the interlace processing unit 110.

  The interlace processing unit 110 stores the CMYK binary data (or 2-bit data) sent from the binarization processing unit in an interlace buffer 124 provided in the ASIC-side SDRAM 102. Then, the interlace processing unit 110 reads the CMYK binary data (or 2-bit data) stored in the interlace buffer 124 into the SRAM 130 in the interlace processing unit 110 for each predetermined size, and the nozzle arrangement on the SRAM 130. Rearranged to correspond to the image buffer unit 112 and sent to the image buffer unit 112.

  The image buffer unit 112 has a function of generating head drive data for ejecting ink to each nozzle for each movement of the printer carriage 41 from the data sent from the interlace processing unit 110. Here, the image buffer unit 112 stores head drive data in image buffers 126 and 127 provided on the SDRAM 102. The image buffers 126 and 127 store head drive data for each time the printer carriage 41 moves once.

The bus controller 114 has a function that enables the CPU 90 to access the ASIC SDRAM 102 connected to the ASIC 94. The control unit 49 is used when the head control unit 116 is driven based on the head drive data generated by the image buffers 126 and 127.
The head control unit 116 has a function of driving the head 21 based on the head drive data under the control of the CPU 90 and discharging ink from the nozzles # 1 to # 180 of the head 21.

(B) Data flow in the control unit << 1 >> Data flow at the time of the scanner function From the host computer 140 connected to the USB interface 118 of the ASIC 94, an image reading command signal from the scanner unit 10, a reading resolution, a reading area, and the like Is read to the control unit 49. In the control unit 49, the scanner control unit 104 is controlled based on the image reading command signal and the reading information data, and reading of the document 5 by the scanner unit 10 is started. At this time, the scanner control unit 104 drives a lamp driving unit, a CCD driving unit, a scanner carriage movement driving unit, and the like, and reads RGB data from the CCD sensor 72 at a predetermined cycle. The read RGB data is temporarily stored in a line buffer 120 provided in the ASIC SDRAM 102, and an inter-line correction process for R, G, and B data is performed. Thereby, RGB image data is generated. The generated RGB image data is sent to the host computer 140 via the USB interface 118.

<< 2 >> Data Flow During Printer Function During the printer function, the printer driver of the host computer 140 converts image data into head drive data, and the head drive data is input from the USB interface 118. For example, when performing interlaced printing, the head drive data includes the resolution of the image to be printed, the pitch of the nozzles # 1 to # 180 included in the nozzle rows 211C, 211M, 211Y, and 211K of the carriage 41 for the printer. The raster data corresponding to the number is extracted, rearranged in the order of printing for each movement of the printer carriage 41, and serves as a signal for driving the head unit 100.

  The head drive data is stored in the image buffer 132 assigned to the SDRAM 96 connected to the CPU bus 98. The image buffer 132 includes two memory areas (image buffers 133 and 134). Each of the image buffers 133 and 134 has a capacity capable of storing head drive data for printing by a single movement of the carriage 41 for the printer. When data for one movement is written in one image buffer 133, the data is transferred to the head control unit 116. At this time, when the image data of one image buffer 133 is transferred to the head control unit 116, head drive data for printing in the next movement is stored in the other image buffer 134. When data for one movement is written in the other image buffer 134, the data is transferred to the head control unit 116, and the image data is written in the one image buffer 133. As described above, the head 21 is driven by the head control unit 116 and printing is performed while alternately writing and reading the head drive data using the two image buffers 133 and 134.

<< 3 >> Data Flow in Copy Function Next, the data flow in the copy function will be described. During the copy function, the document set on the document table is read by the scanner unit 10. The image data read by the scanner unit 10 is taken into the line buffer 120 via the scanner control unit 104. The RGB data taken into the line buffer 120 is subjected to the RGB inter-line correction processing described above in order, and is sequentially sent from the scanner control unit 104 to the binarization processing unit 108 as RGB image data.

  The binarization processing unit 108 performs halftone processing on the received RGB image data. Here, the binarization processing unit 108 converts the RGB image data into binary data for each color of CMYK based on a lookup table 136 (LUT) in the SDRAM 102. The CMYK binary data converted by the binarization processing unit is sent to the interlace processing unit 110.

  The CMYK binary data sent to the interlace processing unit 110 is stored in an interlace buffer 124 provided in the ASIC-side SDRAM 102. The CMYK binary data stored in the interlace buffer 124 is read into the SRAM 130 in the interlace processing unit 110 for each predetermined size, and rearranged on the SRAM 130 so as to correspond to the nozzle arrangement. 110 is sent to the image buffer unit 112.

  The image buffer unit 112 burst-transfers the image data finely divided by the capacity of the SRAM 130 to the image buffers 126 and 127. Here, the image buffer unit 112 generates head drive data for causing the nozzles # 1 to # 180 to eject ink for each movement of the carriage 41 for the printer.

  The head drive data of the image buffers 126 and 127 is controlled by the CPU 90, read into the CPU 90 via the bus controller 114, and transferred to the head control unit 116 by the CPU 90. The head unit 100 is driven by the head control unit 116 based on the head drive data, and an image is printed on the medium S.

  During normal copy operation, layout processing that requires computation by the CPU 90 is performed from when RGB image data is read by the scanner control unit 104 to when CMYK head drive data is written to the image buffers 126 and 127. Not. That is, the process of converting the RGB image data into CMYK head drive data does not require the CPU 90 and is processed mainly by the ASIC 94. Therefore, it is not necessary to transfer data between the ASIC SDRAM 102 and the CPU SDRAM 96 during this process. That is, since data is transmitted between the ASIC 94 and the ASIC SDRAM 102 using only the local bus 128, the CPU bus 98 is hardly used. For this reason, the processing becomes faster and the copy speed can be increased.

<Control part of this embodiment>
(A) Overview of Configuration FIG. 10 is a block configuration diagram illustrating a configuration of the control unit 50 of the present embodiment. As in the conventional case, the conventional control unit 50 includes a CPU 90 that controls the entire SPC multifunction apparatus 1, a memory 92 that stores a control program, and a scanner function, a print function, and a local copy function. Are connected to each other by an CPU bus 98, an SDRAM 96 capable of directly reading and writing data from the CPU 90, and an operation panel 2 as input means. The ASIC 95 includes a scanner unit 10, a head unit 100, and an ASIC SDRAM 102 that allows the ASIC 95 to read and write data, and an SDRAM controller 103 that controls the ASIC SDRAM 102. That is, the control unit 50 is a control unit (controller) for performing various controls of the SPC multifunction apparatus 1. However, the ASIC 95 mounted here is different in configuration from the conventional ASIC 94. The configuration of the ASIC 95 will be described in detail.

  As shown in the figure, the ASIC 95 includes a scanner control unit 104, an image buffer unit 112, a bus controller 114, a head control unit 116, and a USB interface 118, as in the prior art. In addition, the ASIC 95 replaces the conventional resizing unit 106, binarization processing unit 108 and interlace unit 110 with a color conversion processing unit 180, a multi-value processing unit 182, and a dot formation data generation unit 184. It has. The color conversion processing unit 180, the multi-value processing unit 182 and the dot formation data generation unit 184 perform processing different from that of the conventional resizing unit 106, binarization processing unit 108 and interlace unit 110. On the other hand, the scanner control unit 104, the bus controller 114, the head control unit 116, and the USB interface 118 perform the same processing as in the conventional case.

  The units provided in the ASIC 95, that is, the scanner control unit 104 and the image buffer unit 112, the bus controller 114, the head control unit 116, the USB interface 118, the color conversion processing unit 180, the multi-value processing unit 182 and the dot formation. The data generation unit 184 is constituted by various processing circuits, and is realized by hardware.

  The multi-value processing unit 182 corresponds to an “encoder” and a “multi-value processing unit”, and the dot formation data generation unit 184 corresponds to a “decoder” and a “dot formation data generation unit”.

  The ASIC SDRAM 102 is provided with a line buffer 120, a look-up table 136 (LUT), and image buffers 126 and 127 as in the conventional case. In addition, the ASIC SDRAM 102 is provided with a multi-value gradation value data buffer 188 and a dot formation data buffer 190 in place of the conventional resize buffer 122 and interlace buffer 124. Hereinafter, the color conversion processing unit 180, the multi-value quantization processing unit 182 and the dot formation data generation unit 184 will be described in detail.

  The color conversion processing unit 180 converts RGB image data of a predetermined resolution (for example, 360 dpi (horizontal) × 360 dpi (vertical)) output from the scanner control unit 104 into CMYK colors corresponding to the ink colors of the printer unit 30. A process of converting to CMYK image data represented by a space is performed. Here, the color conversion processing unit 180 converts the gradation value of each color (here, three colors of R (red), G (green), and B (blue)) of each pixel of the RGB image data, and the CMYK image data. Using a color conversion table LUT that associates gradation values of each color of each pixel (here, for example, four colors of C (cyan), M (magenta), Y (yellow), and K (black)). Perform color conversion processing. Note that the CMYK image data corresponds to “first image data” in the present embodiment.

  By this color conversion processing, CMYK image data of 256 gradations for each color of C (cyan), M (magenta), Y (yellow), and K (black) is generated. The color conversion processing unit 180 sequentially performs color conversion processing for each pixel on the RGB image data sent from the scanner control unit, and sends the CMYK image data to the multi-value processing unit 182 pixel by pixel.

  The multi-value processing unit 182 multi-values each color tone value of each pixel of the CMYK image data generated by the color conversion processing unit 180 and converts it into multi-value tone value data. In this conversion, the multi-value processing unit 182 corresponds to the resolution (output resolution) when printing the gradation value of each color of each pixel of the CMYK image data on the medium S for each color of each pixel. Convert to multi-value gradation value data. The multilevel processing performed here will be described in detail later. The multilevel tone value data generated by this multilevel processing is stored in the multilevel tone value data buffer 188 provided in the ASIC SDRAM 102 by the multilevel processing unit 182.

  The dot formation data generation unit 184 obtains the multi-value gradation value data generated by the multi-value processing unit 182 from the multi-value gradation value data buffer 188. Then, the dot formation data generation unit 184 generates dot formation data for an image printed on the medium S (also referred to as a second image or an output image) based on the acquired multi-value gradation value data. This dot formation data corresponds to “second image data” in the present embodiment. The dot formation data generation process performed here will be described in detail later. The dot formation data generation unit 184 stores the generated dot formation data in a dot formation data buffer 190 provided in the ASIC SDRAM 102.

  The dot formation data stored in the dot formation data buffer 190 is read by the image buffer unit 112. The image buffer unit 112 transfers the dot formation data acquired from the dot formation data buffer 190 to the image buffers 126 and 127 and ejects ink to each nozzle for each movement of the carriage 41 for the printer. Generate drive data. The image buffers 126 and 127 store head drive data for each time the printer carriage 41 moves once.

  The head drive data stored in these image buffers 126 and 127 is read into the CPU 90 via the bus controller 114 and transferred to the head control unit 116 by the CPU 90 as in the conventional case.

(B) Data flow in the control unit << 1 >> Data flow at the time of the scanner function The data flow at the time of the scanner function is the same as the conventional one. That is, when the host computer 140 transmits an image reading command signal from the scanner unit 10 and reading information data such as reading resolution and reading area to the control unit 49, the control unit 50 reads the image reading command signal and the reading information. Based on the data, reading of the document 5 is started by the scanner unit 10. At this time, the scanner control unit 104 reads RGB data from the CCD sensor 72. The read RGB data is temporarily stored in a line buffer 120 provided in the ASIC SDRAM 102, subjected to inter-line correction processing for each of the R, G, and B data, and then the USB interface 118 is used as RGB image data. To the host computer 140.

<< 2 >> Data Flow During Printer Function The data flow during the printer function is the same as in the past. That is, the head drive data sent from the host computer is stored in the image buffer 132 assigned to the SDRAM 96 connected to the CPU bus 98. Each of the image buffers 133 and 134 has a capacity capable of storing head drive data for printing by a single movement of the carriage 41 for the printer, and the head drive data stored in each of the image buffers 133 and 134. Is transferred to the head control unit 116. Based on the transferred head drive data, the head control unit 116 drives the head 21 to execute a printing process.

<< 3 >> Data Flow in Copy Function In the copy function, the data flow is as follows. During the copy function, the image of the document 5 placed on the document table 11 is read by the scanner unit 10. The scanner control unit 10 performs an interline correction process on the image data read by the scanner unit 10 and sends the image data to the color conversion processing unit 180 as RGB image data.
The RGB image data sent to the color conversion processing unit 180 is converted into CMYK image data by referring to the color conversion table LUT by the color conversion processing unit 180. The CMYK image data generated by the color conversion processing unit 180 is sent to the multi-value processing unit 182.
The CMYK image data sent to the multi-value processing unit 182 is multi-valued in the multi-value processing unit 182 and converted into multi-value gradation value data. The multi-value gradation value data generated by this conversion is stored in the multi-value gradation value data buffer 188 on the ASIC SDRAM 102 by the multi-value processing unit 182.
The dot formation data generation unit 184 acquires multi-value gradation value data from the multi-value gradation value data buffer 188. The multi-value gradation value data acquired by the dot formation data generation unit 184 is sequentially converted into dot formation data for an image (second image) printed on the medium S. The dot formation data generated by this conversion is stored in the dot formation data buffer 190 on the ASIC SDRAM 102.

  The dot formation data stored in the dot formation data buffer 190 is sequentially read by the image buffer unit 112 and stored as head drive data in the image buffers 126 and 127 by the image buffer unit 112. The head drive data stored in the image buffers 126 and 127 is read into the CPU 90 via the bus controller 114. The head drive data read by the CPU 90 is transferred to the head control unit 116. The head drive data transferred to the head control unit 116 is sequentially sent to the head 21 and printing processing is executed.

=== Multi-value processing unit ===
Hereinafter, the multilevel processing executed by the multilevel processing unit 182 will be described.

<Multi-value processing>
The multi-value processing unit 182 multi-values each color tone value of each pixel of the CMYK image data generated by the color conversion processing unit 180 and converts it into multi-value tone value data. In this conversion, the multi-value processing unit 182 corresponds to the resolution (output resolution) when printing the gradation value of each color of each pixel of the CMYK image data on the medium S for each color of each pixel. To convert to multi-value gradation value data.

  FIG. 11 illustrates an example of a processing procedure of the multi-value processing unit 182 at this time. The multi-value processing unit 182 first obtains the gradation value of each pixel of the CMYK image data and the classification number of each pixel, as will be described with reference to FIG. Here, the classification number will be described in detail later. Next, the multi-value processing unit 182 proceeds to step S152, and acquires multi-value gradation value data based on the acquired gradation value and classification number. Here, the multi-value processing unit 182 acquires multi-value gradation value data using a multi-value conversion table in which the multi-value gradation value data is associated with each gradation value for each classification number. The multi-value table will be described in detail later. Then, the multi-value processing unit 182 outputs the acquired multi-value gradation value data as multi-value gradation value data corresponding to the gradation value of the pixel of the CMYK image data (S154). After completing the conversion process in this way, the multi-value quantization processing unit 182 checks whether there is a pixel to be converted next (S156). Here, when there is a pixel to be converted next, the multi-value processing unit 182 returns to step S150, and again converts the gradation value of the pixel to be converted into multi-value gradation value data. Execute the process. The multi-value processing unit 182 executes such processing until there are no more pixels to be converted. If there is no pixel to be converted next, the multi-value processing unit 182 ends the processing promptly.

<Multi-value table>
FIG. 12A is an explanatory diagram conceptually illustrating an example of a multi-value conversion table used when acquiring multi-value gradation value data based on the gradation value and classification number of a pixel. As shown in the figure, the multi-value conversion table is a table in which multi-value gradation value data is set in association with each pixel gradation value for each pixel classification number. For example, as shown in the figure, the multi-value conversion table has “pixel classification number” in the vertical direction and “pixel gradation value” in the horizontal direction, and “classification number” and “gradation value”. The corresponding multi-value gradation value data can be derived from the above. Here, the “gradation value” is represented by 256 gradations from “0” to “255”. The “classification number” is a number assigned to each pixel of CMYK image data, and here, numbers “1” to “1024” are assigned. The multi-value gradation value data takes values of “0” to “31” according to the gradation values of “0” to “255” and the classification numbers of “1” to “1024”. It has become. The multi-value gradation value data increases stepwise as the gradation value of the pixel increases.

  In the present embodiment, data relating to such a multi-value table is stored in the SDRAM 102 on the ASIC 95 side. The multi-value processing unit 182 performs multi-value processing stored in the SDRAM 102 on the ASIC 95 side when multi-value processing is performed on each color gradation value of each pixel of the CMYK image data sent from the color conversion processing unit 180. Multi-value gradation value data is generated with reference to the table.

  Note that the data related to the multi-level table stored in the SDRAM 102 on the ASIC 95 side is stored in, for example, a non-volatile memory such as the ROM 92 mounted on the SPC composite apparatus 1, and the multi-level processing unit 182 multi-levels the data. When executing the processing, it is read from a nonvolatile memory such as the ROM 92 and stored in the SDRAM 102 on the ASIC 95 side.

<Number of multi-value stages>
FIG. 12B is an explanatory diagram exemplifying how multi-value gradation value data increases stepwise as the gradation value of a pixel increases. Here, as shown in the figure, in the line graph in which the horizontal axis represents the pixel gradation value and the vertical axis represents the multi-value gradation value data, the multi-value gradation value data with respect to the pixel gradation value. Is shown. The classification numbers N1 to N5 represent different classification numbers. The multi-value quantization results for the five pixels corresponding to these classification numbers N1 to N5 are shown. Here, the origin position of the multi-value gradation value data is displayed while being shifted little by little in the vertical axis direction in order to prevent the broken lines of the respective classification numbers N1 to N5 from being overlapped and difficult to discriminate.

  In the figure, a classification number N1 indicated by a thick solid line will be described. The multi-value gradation value data is “0” when the gradation value of the pixel is in the range of “0” to “4”, but is large when the gradation value of the pixel is in the range of “5” to “20”. The value gradation value data increases to “1”. Further, in the range where the gradation value of the pixel is “21” to “42”, the multi-value gradation value data increases to “2”. Further, in the range where the gradation value of the pixel is “43” to “69”, the multi-value gradation value data increases to “3”. Thus, as the gradation value of the pixel increases, the multi-value gradation value data also increases stepwise. Finally, the multi-value gradation value data increases to “15”. That is, for the classification number N1, the gradation value of the pixel that can take the range of gradation values “0” to “255” is multi-valued (in other words, 16 levels from gradation values “0” to “15”). , 16-valued).

  Similarly, for the classification number N2 indicated by a thick broken line in the figure and the classification number N3 indicated by a thick dashed line, the gradation value of a pixel that can take a range of gradation values “0” to “255” is Multi-values (in other words, 18-values) are provided in 18 levels from gradation values “0” to “17”. Further, for the classification number N4 indicated by the thin solid line and the classification number N5 indicated by the thin one-dot chain line, the gradation value of the pixel is multi-valued in 21 steps from gradation values “0” to “20” (in other words, 21 values). As described above, in the multi-value processing unit 182, the number of multi-value levels of each pixel (the number of states that can be obtained as a result of multi-value conversion) is not the same, and multi-value is obtained with a specific number of levels according to the pixel classification number. It has become. As a result, even when the gradation values of the same pixel are multi-valued, the number of multi-value levels differs if the pixel classification number is different. For this reason, even if the gradation values of the pixels are the same, they are converted into different multi-value gradation value data.

  Further, even if the number of multi-value levels is the same, the same multi-value gradation value data is not obtained. For example, as apparent from a comparison between the classification number N2 shown in FIG. 12B and the classification number N3, the number of multi-levels for these pixels is 18 in all cases, but the multi-value gradation value data is In many cases, the gradation values of the pixels to be switched do not match. Similarly, for the classification number N4 and the classification number N5, the number of multilevel gradation levels of these pixels is 21, but the gradation values of the pixels to which the multilevel gradation value data is switched do not match. There are many cases. For this reason, even if the number of multi-value levels of pixels is the same, different multi-value gradation value data can be obtained if the classification numbers are different.

  As described above, although the multi-value gradation value data differs depending on the classification number, the number of stages of multi-value conversion is about 15 to 21. That is, it is considered that the number of stages of multi-leveling does not exceed 30 even if it is estimated a lot. Therefore, multi-value gradation value data can be expressed sufficiently if there is a data amount of 5 bits.

<Classification number setting>
Here, a method for setting the classification number for each pixel of the CMYK image data will be described. The classification number setting method for each pixel of the CMYK image data differs depending on the resolution (output resolution) when the image is printed on the medium S. That is, if the resolution (output resolution) when printing an image on the medium S is different, the method of assigning the classification number to each pixel of the CMYK image data is different.
In the present embodiment, there are seven types of resolutions (output resolutions) when printing an image on the medium S. In other words, “1 × 1 mode”, “2 × 1 mode”, “1 × 2 mode”, “2 × 2 mode”, “4 × 2 mode”, “2 × 4 mode”, There are seven types of “4 × 4 mode”.

(1) Output Resolution Here, “1 × 1 mode” is a mode in which an image is printed on the medium S at the same resolution as the resolution of CMYK image data. That is, for example, when an image is printed based on CMYK image data having a resolution of 360 dpi (horizontal) × 360 dpi (vertical), the resolution of the printed image is a resolution of 360 dpi (horizontal) × 360 dpi (vertical). The “2 × 1 mode” is a mode for printing an image on the medium S by doubling the horizontal resolution of the CMYK image data. That is, for example, when an image is printed based on CMYK image data having a resolution of 360 dpi (horizontal) × 360 dpi (vertical), the resolution of the printed image is a resolution of 720 dpi (horizontal) × 360 dpi (vertical). As for the vertical resolution, the image is printed at the same resolution as the CMYK image data.

  The “1 × 2 mode” is a mode for printing an image on the medium S by doubling the vertical resolution of the CMYK image data. That is, for example, when printing an image based on CMYK image data having a resolution of 360 dpi (horizontal) × 360 dpi (vertical), the resolution of the printed image is a resolution of 360 dpi (horizontal) × 720 dpi (vertical). As for the horizontal resolution, the image is printed at the same resolution as the CMYK image data.

  The “2 × 2 mode” is a mode for printing an image on the medium S by doubling the horizontal and vertical resolutions of the CMYK image data. That is, for example, when an image is printed based on CMYK image data having a resolution of 360 dpi (horizontal) × 360 dpi (vertical), the resolution of the printed image is a resolution of 720 dpi (horizontal) × 720 dpi (vertical). The “4 × 2 mode” is a mode in which an image is printed on the medium S with the horizontal resolution of the CMYK image data being quadrupled and the vertical resolution of the CMYK image data being doubled. That is, for example, when an image is printed based on CMYK image data having a resolution of 360 dpi (horizontal) × 360 dpi (vertical), the resolution of the printed image is a resolution of 1440 dpi (horizontal) × 720 dpi (vertical).

  The “2 × 4 mode” is a mode for printing an image on the medium S by doubling the horizontal resolution of the CMYK image data and quadrupling the vertical resolution of the CMYK image data. That is, for example, when an image is printed based on CMYK image data having a resolution of 360 dpi (horizontal) × 360 dpi (vertical), the resolution of the printed image is a resolution of 720 dpi (horizontal) × 1440 dpi (vertical). The “4 × 4 mode” is a mode for printing an image on the medium S by multiplying the horizontal and vertical resolutions of the CMYK image data by four times. That is, for example, when an image is printed based on CMYK image data having a resolution of 360 dpi (horizontal) × 360 dpi (vertical), the resolution of the printed image is a resolution of 1440 dpi (horizontal) × 1440 dpi (vertical).

(2) Classification Number Setting by Resolution FIGS. 13A to 13E respectively explain a method for setting a classification number corresponding to each output resolution. FIG. 13A shows “1 × 1 mode”, that is, a case where an image is printed on the medium S at a resolution of 360 dpi (horizontal) × 360 dpi (vertical) here. FIG. 13B shows a case where an image is printed on the medium S at a resolution of “2 × 1 mode”, that is, here, 720 dpi (horizontal) × 360 dpi (vertical). FIG. 13C shows a case where an image is printed on the medium S at a resolution of “1 × 2 mode”, that is, 360 dpi (horizontal) × 720 dpi (vertical) here. FIG. 13D shows a case of printing an image on the medium S at a resolution of “2 × 2 mode”, that is, here, 720 dpi (horizontal) × 720 dpi (vertical). FIG. 13E shows a case where the image is printed on the medium S at a resolution of “4 × 2 mode”, that is, here, 1440 dpi (horizontal) × 720 dpi (vertical). Here, for the “2 × 4 mode” and the “4 × 4 mode”, the same setting process as in the “4 × 2 mode” is performed.

  In the “1 × 1 mode”, as shown in FIG. 13A, among the pixels constituting the CMYK image data, eight adjacent pixels are set as one unit, and the classification number is set. That is, of the pixels constituting the CMYK image data, the eight adjacent pixels are all set to the same classification number. Here, 4 pixels in the horizontal direction and 2 pixels in the vertical direction, with a total of 8 pixels as one unit, the same classification number is assigned to each of these 8 pixels. That is, here, as shown in the figure, the eight pixels located in the upper left corner of the CMYK image data are set to the classification number “1”, for example.

  On the other hand, for the eight pixels (four pixels in the horizontal direction and two pixels in the vertical direction) on the right side of the eight pixels with the classification number “1” set, for example, the classification number “2” is set. Further, for the eight pixels (4 pixels in the horizontal direction and 2 pixels in the vertical direction) adjacent to the lower side of the eight pixels with the classification number “1” in the figure, for example, the classification number “33” is set. . Further, for the eight pixels at the lower right in the figure (4 pixels in the horizontal direction and 2 pixels in the vertical direction) of the eight pixels to which the classification number “1” is set, for example, the classification number “34” is set.

  In the “2 × 1 mode”, as shown in FIG. 13B, among the pixels constituting the CMYK image data, four adjacent pixels are set as one unit, and the classification number is set. That is, four adjacent pixels among the pixels constituting the CMYK image data are all set to the same classification number. Here, two pixels in the horizontal direction and two pixels in the vertical direction, with a total of four pixels as one unit, the same classification number is set for each of these four pixels. That is, here, as shown in the figure, the four pixels located at the upper left corner of the CMYK image data are set to the classification number “1”, for example.

  On the other hand, the classification number “2” is set, for example, for the four pixels (two pixels in the horizontal direction and two pixels in the vertical direction) adjacent to the right in the drawing of the four pixels having the classification number “1”. Furthermore, for example, the classification number “3” is set to the four pixels (two pixels in the horizontal direction and two pixels in the vertical direction) on the right side in the figure. Further, for the four pixels adjacent to the lower side in the figure of the four pixels set with the classification number “1” (2 pixels in the horizontal direction and 2 pixels in the vertical direction), for example, the classification number “33” is set. . In this way, similarly for the other pixels constituting the CMYK image data, classification numbers are set for each of the four adjacent pixels as one unit.

  In the case of the “1 × 2 mode”, as shown in FIG. 13C, among the pixels constituting the CMYK image data, four adjacent pixels are set as one unit, and a classification number is set. That is, four adjacent pixels among the pixels constituting the CMYK image data are all set to the same classification number. Here, four pixels in the horizontal direction and one pixel in the vertical direction, with a total of four pixels as one unit, the same classification number is set for each of these four pixels. That is, here, as shown in the figure, the four pixels located at the upper left corner of the CMYK image data are set to the classification number “1”, for example.

  On the other hand, for the four pixels (four pixels in the horizontal direction and one pixel in the vertical direction) adjacent to the right of the four pixels in which the classification number “1” is set, for example, the classification number “2” is set. For the four pixels (4 pixels in the horizontal direction and 1 pixel in the vertical direction) adjacent to the lower side of the four pixels with the classification number “1” in the figure, for example, the classification number “33” is set. . Further, four pixels (4 pixels in the horizontal direction and 1 pixel in the vertical direction) adjacent to the lower side of the four pixels with the classification number “33” in the figure are set to the classification number “5”, for example. Further, for the four pixels (4 pixels in the horizontal direction and 1 pixel in the vertical direction) adjacent on the lower side in the figure, for example, the classification number “97” is set. In this way, similarly for the other pixels constituting the CMYK image data, classification numbers are set for each of the four adjacent pixels as one unit.

  In the case of the “2 × 2 mode”, as shown in FIG. 13D, classification numbers are set for two adjacent pixels as one unit among the pixels constituting the CMYK image data. That is, of the pixels constituting the CMYK image data, two adjacent pixels are all set to the same classification number. Here, two pixels in the horizontal direction and one pixel in the vertical direction, with a total of two pixels as one unit, the same classification number is set for each of these two pixels. That is, here, as shown in the figure, for example, the two pixels located at the upper left corner of the CMYK image data are set to the classification number “1”, for example.

  On the other hand, for the two pixels (two pixels in the horizontal direction and one pixel in the vertical direction) adjacent to the right of the two pixels with the classification number “1” in the figure, the classification number “2” is set, for example. Furthermore, the classification number “3” is set, for example, in the two pixels (two pixels in the horizontal direction and one pixel in the vertical direction) adjacent to the right of the two pixels in which the classification number “2” is set. Furthermore, for example, the classification number “4” is set in the two pixels on the right side in the figure (two pixels in the horizontal direction and one pixel in the vertical direction). Also, for two pixels adjacent to the lower side in the figure of the two pixels set with the classification number “1” (2 pixels in the horizontal direction and 1 pixel in the vertical direction), for example, the classification number “33” is set. . Furthermore, for example, a classification number “5” is set for two pixels (two pixels in the horizontal direction and one pixel in the vertical direction) adjacent to the lower side in the figure of the two pixels having the classification number “33”. . Furthermore, for the two pixels adjacent to the lower side in the figure (two pixels in the horizontal direction and one pixel in the vertical direction), for example, a classification number “97” is set. In this way, similarly for the other pixels constituting the CMYK image data, the classification numbers are respectively set with two adjacent pixels as one unit.

  In the “4 × 2 mode”, as shown in FIG. 13E, a different classification number is set for each pixel constituting the CMYK image data. That is, here, as shown in the figure, for example, the classification number “1” is set to the pixel located in the upper left corner of the CMYK image data. Further, another classification number is set for other pixels adjacent to this pixel. That is, for example, the classification number “2” is set, for example, in the pixel on the right side of the pixel to which the classification number “1” is set. In addition, for example, a classification number “3” is set to the pixel on the right side of the pixel to which the classification number “2” is set. Furthermore, for example, the classification number “4” is set to the pixel on the right side of the pixel to which the classification number “3” is set.

  On the other hand, for example, a classification number “33” is set to the pixel adjacent to the lower side in the figure of the pixel for which the classification number “1” is set. Further, for example, a classification number “65” is set to a pixel adjacent to the lower side in the figure of the pixel for which the classification number “33” is set. Furthermore, for example, a classification number “97” is set to a pixel adjacent to the lower side of the pixel in which the classification number “65” is set.

  In the case of “2 × 4 mode” and “4 × 4 mode”, classification numbers are set in the same manner as in the case of “4 × 2 mode”.

  As described above, the setting of the classification number of each pixel of the CMYK image data is performed by different methods depending on the resolution (output resolution) when the image is printed on the medium S. Based on the classification number set in this way, the multi-value processing unit 182 performs multi-value processing on each color gradation value of each pixel of the CMYK image data generated by the color conversion processing unit 180, and performs multi-value processing. Value gradation value data is generated.

<Process actually executed>
The multi-value processing unit 182 sequentially converts the CMYK image data sent from the color conversion processing unit 182 pixel by pixel into multi-value gradation value data. FIG. 14 schematically illustrates an image of processing performed at this time. As shown in the figure, the multilevel processing unit 182 sequentially performs conversion processing for each pixel and for each raster line while changing the pixel of interest on the CMYK image data. That is, the multi-value processing unit 182 first converts each pixel of the raster line L1 of the first row on the CMYK image data sequentially, as described in FIG. The conversion process is sequentially performed on each pixel of the raster line L2. Then, after the conversion process is completed for each pixel of the raster line L2 in the second row, the multi-value processing unit 182 performs the conversion process for each pixel of the raster line L3 in the third line. In this way, the multi-value processing unit 182 sequentially converts the CMYK image data sent from the color conversion processing unit 182 for each raster line while shifting the pixel of interest one pixel at a time.

=== Generation of dot formation data ===
<Generation of dot formation data>
The dot formation data generation unit 184 generates dot formation data for an image (second image) printed on the medium S based on the multi-value gradation value data generated by the multi-value processing unit 182. In addition, the multi-value gradation value data is converted into dot number data. Next, the dot formation data generation unit 184 determines whether or not to form dots individually for one or more pixels based on the dot number data obtained by the conversion. Then, the dot formation data generation unit 184 prints at least some of the one or more pixels determined to be dot-formed as pixels constituting the image to be printed (second image). The dot formation data of the image to be processed (second image) is generated.

  FIG. 15 shows an example of the processing procedure of the dot formation data generation unit at this time. The dot formation data generation unit 184 first acquires multi-value gradation value data and a corresponding classification number (S202), as will be described with reference to FIG. Here, the classification number corresponding to the multi-value gradation value data is the classification number used when the multi-value gradation value data is generated. Next, the dot formation data generation unit 184 acquires dot number data based on the acquired multi-value gradation value data and the classification number (S204). This dot number data is data representing the number of dots to be formed. In the present embodiment, the dot number data is encoded to represent not only the number of dots to be formed but also the size of each dot to be formed (ie, “small dot”, “medium dot”, “large dot”). It has become the data. This dot number data will be described in detail later. Here, the dot formation data generation unit 184 obtains the dot number data using a dot number data conversion table in which the dot number data is associated with each multi-value gradation value data for each classification number. The dot number data conversion table will be described in detail later.

  Next, the dot formation data generation unit 184 determines the presence or absence of dot formation for each of one or more pixels based on the acquired dot number data (S206). In the present embodiment, the dot formation data generation unit 184 determines whether or not to form dots for each of the eight pixels based on the acquired dot number data. In determining whether or not to form dots, the size of dots to be formed is also determined.

  Next, the dot formation data generation unit 184 generates dot formation data based on one or more pixels (eight pixels here) for which the presence or absence of dot formation has been determined (S208). Specifically, at least a part of pixels is cut out from one or more pixels (in this case, eight pixels) for which dot formation has been determined or not, and the cut out pixels are used as the pixels constituting the image to be printed. Use as data. Here, for one or more pixels (eight pixels here) for which the presence or absence of dot formation is determined, all the pixels may be cut out and used as data of pixels constituting an image to be printed. The number of pixels cut out from one or more pixels (here, eight pixels) for which the presence or absence of dot formation has been determined varies depending on the resolution (output resolution) when an image is printed on the medium S. In this way, dot formation data is generated by the dot formation data generation unit 184.

  After completing the generation of dot formation data for certain multi-value gradation value data, the dot formation data generation unit 184 next checks whether there is any multi-value gradation value data to be processed (S210). Here, if there is multi-value gradation value data to be processed next, the dot formation data generation unit 184 returns to step S202, and again, for the multi-value gradation value data to be processed, dot processing is performed. A process of generating formation data is executed. The dot formation data generation unit 184 executes such processing until there are no more pixels to be processed. If there is no more multi-value gradation value data to be processed, the dot formation data generation unit 184 immediately ends the processing.

<Dot count data conversion table>
FIG. 16 conceptually illustrates an example of a dot number data conversion table used when converting multi-value gradation value data into dot number data. This dot number data conversion table is a table in which dot number data is set in association with each multi-value gradation value data for each classification number, as shown in FIG. In the dot number data conversion table, for example, as shown in the figure, “classification number” is set in the vertical direction and “multilevel gradation value data” is set in the horizontal direction, and “classification number” and “multilevel scale” are set. Corresponding dot number data can be derived from the “value data”. Here, the “classification number” is represented by numbers “1” to “1024” as described above. The “multi-value gradation value data” is represented by numerical values from “0” to “31”. In addition, the “dot number data” is represented by numerical values “0” to “164” here. The dot number data is individually prepared according to the classification numbers “1” to “1024” and the multi-value gradation value data “0” to “31”.

  As an example, the classification number “1” will be described. For the multi-value gradation value data “0”, “0” is set in the dot number data. For the multi-value gradation value data “3”, “3” is set as the dot number data. For the multi-value gradation value data “14”, “157” is set as the dot number data. Further, “164” is set as the dot number data for the multi-value gradation value data “15”.

  In the present embodiment, data regarding such a dot number data conversion table is stored in the SDRAM 102 on the ASIC 95 side. The dot formation data generation unit 184 refers to data relating to a dot number data conversion table stored in the SDRAM 102 on the ASIC 95 side when converting the acquired multi-value gradation value data into dot number data.

  The data related to the dot number data conversion table stored in the SDRAM 102 on the ASIC 95 side is stored in, for example, a non-volatile memory such as the ROM 92 mounted in the SPC multifunction apparatus 1, and the dot formation data generation unit 184 displays the dot data. In the conversion to the number data, the data is read from a nonvolatile memory such as the ROM 92 and stored in the SDRAM 102 on the ASIC 95 side.

<Dot count data>
As described above, the dot number data of the present embodiment is a code representing not only the number of dots to be formed but also the size of each dot to be formed (that is, “small dot”, “medium dot”, “large dot”). It has become data.

  FIG. 17 illustrates an example of a correspondence relationship between the dot number data and information regarding the number and size of dots to be formed, which are represented by the dot number data. As described above, the dot number data takes values from “0” to “164”. Each numerical value “0” to “164” of the dot number data represents the presence / absence of dot formation and the dot size. That is, the dot count data “0” indicates that “large dot”, “medium dot”, and “small dot” are not formed. Also, the dot number data “1” represents that only one “small dot” is formed. The dot number data “2” indicates that only two “small dots” are formed. The dot number data “3” indicates that only three “small dots” are formed. The dot number data “160” indicates that six “large dots” are formed, two “medium dots” are formed, and “small dots” are not formed. The dot number data “161” indicates that only seven “large dots” are formed. The dot number data “164” indicates that only eight “large dots” are formed.

The dot number data is represented in this way for the following reason. That is, in the present embodiment, it is determined whether or not to form dots for each of the eight pixels based on the acquired dot number data. In short, the maximum number of dots that can be formed for eight pixels is eight. For example, a combination of the number of dots such as four large dots, three medium dots, and two small dots cannot be generated in reality because the total number of dots exceeds nine and exceeds eight. . Focusing on these points, it is considered that there are not so many kinds of combinations of the number of dots that can actually occur. The actual calculation is as follows. In other words, with regard to eight pixels, four states can be taken: “form a large dot”, “form a medium dot”, “form a small dot”, and “do not form a dot”. Therefore, the combination of the number of dots can be obtained by ₄ H ₈ (= _{4 + 8-1} C ₈ ) because these four states are equal to the number of combinations when eight times are selected while allowing overlap. Therefore, only 165 combinations appear at most. Here, _n H _r is an operator for obtaining the number of overlapping combinations when r times are selected from n objects by allowing duplication. _N C _r is an operator for obtaining the number of combinations when selecting r times from n objects without allowing duplication. If there are 165 combinations, 8 bits can be expressed.

  On the other hand, if an attempt is made to express the number of dots without coding them, the data amount is 12 bits in total, 4 bits each for representing the number of large dots, the number of medium dots, and the number of small dots. Necessary. Therefore, if a code number is set for a combination of the number of dots that can actually occur, the combination of the number of dots to be formed can be represented by 8-bit data. Eventually, by encoding the combination of the number of dots, it is possible to reduce the amount of data required as compared with the case where the number of formation is represented for each type of dot.

  Of course, as the dot number data, 12-bit data in which the number of dots of each size is expressed without being coded may be used instead of the above-described 8-bit data.

<Determination of dot formation>
In this embodiment, the dot formation data generation unit 184 determines whether or not to form dots for one or more pixels based on the acquired dot number data. In this embodiment, the dot formation data generation unit 184 determines the dot size and the presence / absence of dot formation for each of eight pixels (4 horizontal pixels and 2 vertical pixels) based on the dot number data. Here, the determination of the presence or absence of dot formation for each of the eight pixels is performed based on the order value matrix. This order value matrix corresponds to “dot formation order data”.

  Here, the order value matrix is a matrix in which the order in which dots are to be formed is set for eight pixels. In this order value matrix, numbers representing the order in which dots are to be formed for a total of 8 pixels, 4 horizontal pixels and 2 vertical pixels, are set. The numbers indicating the dot formation order set for each of the eight pixels are individually set for each classification number. That is, the order value matrix is set to a different matrix for each classification number.

<Order value matrix>
FIG. 18 illustrates an example of the order value matrix used here. FIG. 18A illustrates an example of an order value matrix set corresponding to the classification number “1”. FIG. 18B illustrates an example of the order value matrix set corresponding to the classification number “2”. FIG. 18C illustrates an example of the order value matrix set corresponding to the classification number “3”.

  As shown in FIG. 18A, the order value matrix corresponding to the classification number “1” is a number “ 1 "is set. The numerical value “1” set in the upper left corner pixel in this way indicates that this pixel should form a dot first among eight pixels. Note that the numerical values representing such order set in the order value matrix are also referred to as order values. In addition, the order value “2” is set to the pixel in the lower right corner among the eight pixels, which means that this pixel should form the second dot among the eight pixels. In this manner, the order value matrix is set with order values indicating the order in which dots are formed for the eight pixels. Here, since the number of pixels is eight, the numbers “1” to “8” are set to the eight pixels as the order values. Note that the order values set for the eight pixels are different.

  On the other hand, as shown in FIG. 18B, the order value matrix corresponding to the classification number “2” is the pixel where the first dot is to be formed (the pixel having the order value “1”) from the lower left. This is the second pixel. Further, the pixel in which a dot is to be formed second (the pixel having the order value “2”) is the pixel in the lower right corner. Here, in the order value matrix corresponding to the classification number “3”, as shown in FIG. 18B, the pixel in which the dot is to be formed first (the pixel having the order value “1”) is from the upper right. This is the second pixel. Further, the pixel in which a dot is to be formed second (the pixel having the order value “2”) is the pixel in the lower left corner.

  In the present embodiment, data relating to such an order value matrix is stored in the SDRAM 102 on the ASIC 95 side. The dot formation data generation unit 184 refers to information on the order value matrix stored in the SDRAM 102 on the ASIC 95 side when determining the presence or absence of dot formation for each of one or more pixels based on the acquired dot number data.

  Note that the information regarding the order value matrix stored in the SDRAM 102 on the ASIC 95 side is stored in, for example, a non-volatile memory such as the ROM 92 mounted in the SPC multifunction apparatus 1, and the dot formation data generation unit 184 stores the dot count data. Based on the above, when determining the presence or absence of dot formation for each of one or more pixels, it is read from a nonvolatile memory such as the ROM 92 and stored in the SDRAM 102 on the ASIC 95 side.

<Decision for each pixel>
After acquiring the data related to the order value matrix in this way, the dot formation data generation unit 184 next determines, from among the eight pixels, a pixel that forms a large dot first. Since the large dots are more conspicuous than the other dots, it is desirable to prioritize the pixel positions for forming the dots so that the dots are formed as dispersedly as possible. For this reason, first, a pixel for forming a large dot is determined. In determining the pixels forming the dots, the dot number data obtained by converting the multi-value gradation value data and the corresponding order value matrix are used.

  FIG. 19 conceptually illustrates an example of a procedure for determining the presence or absence of dot formation for each of the eight pixels based on the dot number data and the order value matrix. Here, the dot number data is data indicating that one large dot, two medium dots, and one small dot should be formed, and the order value matrix has the classification number “ An example of the order value matrix corresponding to “1” will be described.

  As described above, in the order value matrix, the order in which dots are formed for each of the eight pixels is set. Here, first, in [First Step], a pixel in which the largest dot, that is, a large dot is formed is determined. Since the number of large dots to be formed is one, the pixels where the large dots are formed are only the pixels for which the order value “1” is set. In other words, among the eight pixels in the figure, the pixels are displayed with fine diagonal lines.

  Next, in [Second Step], a pixel on which the second largest dot, that is, a medium dot is formed is determined. Since the number of medium dots to be formed is two, there are two pixels in which the medium dots are formed: a pixel set with the order value “2” and a pixel set with the order value “3”. become. In other words, among the eight pixels in the figure, the pixels are displayed with a slightly rough diagonal line.

  Then, in [Third Step], a pixel on which a third largest dot, that is, a small dot is formed is determined. Since the number of small dots to be formed is one, the pixels in which the small dots are formed are only the pixels for which the order value “4” is set. In other words, among the eight pixels in the figure, the pixels are displayed with rough diagonal lines.

  In this way, the pixels to be formed are determined from the eight pixels for each of the large dots, medium dots, and small dots. The remaining pixels that are not instructed to be formed for large dots, medium dots, and small dots are pixels that do not form dots. As a result, the dot arrangement finally becomes as shown in the lower part of the figure. The data for forming dots for each of the eight pixels is dot data as shown at the bottom in the figure.

<Cut out pixels>
Next, the dot formation data generation unit 184 cuts out at least some of the eight pixels that have determined the positions and sizes of the dots to be formed in this way, and prints the cut out pixels. It is used as a pixel for image dot formation data. The number of pixels cut out here differs depending on the resolution (output resolution) when printing an image on the medium S. In addition, the position of the pixel cut out from the eight pixels varies depending on the position in the pixel in the CMYK image data when generating the multi-value gradation value data.

(1) In the case of 1 × 1 mode In the case of “1 × 1 mode”, the resolution (output resolution) when printing an image on the medium S is the same as the resolution of CMYK image data. The number is one. FIG. 20 illustrates the positions of pixels cut out from the eight pixels. 20A to 20H respectively show patterns of positions of pixels to be cut out. FIG. 21 illustrates the positions of pixels in CMYK image data.

  FIG. 20A shows a case where a pixel located at the upper left corner of the eight pixels is cut out. FIG. 20B shows a case where the pixel located second from the left in the upper stage among the eight pixels is cut out. FIG. 20C shows a case where the second pixel from the right on the upper stage among the eight pixels is cut out. FIG. 20D shows a case where a pixel located in the upper right corner among the eight pixels is cut out. FIG. 20E shows a case where a pixel located at the lower left corner of the eight pixels is cut out. FIG. 20F shows a case where the pixel located second from the left in the lower stage among the eight pixels is cut out. FIG. 20G shows a case where the pixel located second from the right in the lower stage of the eight pixels is cut out. FIG. 20H shows a case where a pixel located at the lower right corner among the eight pixels is cut out.

  As shown in FIG. 20A, the pixel located in the upper left corner of the eight pixels is cut out because the position of the pixel referred to in the CMYK image data when generating multi-value gradation value data is shown in FIG. Is the position indicated by “(1)”, that is, the position of the upper left corner in the pixel to which the same classification number is set. In other words, here, the upper left of eight pixels of 4 pixels (horizontal) × 2 pixels (vertical) in which the classification numbers “1”, “2”, “33”, and “34” shown in FIG. 21 are set. When the dot formation data is generated based on the multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located at the corner, the pixel extraction method as shown in FIG. 20A is executed. . Here, pixel data “11” is acquired as dot formation data by such a cutting method.

  Also, as shown in FIG. 20B, the second pixel from the left in the upper stage among the eight pixels is cut out because the pixel referred to in the CMYK image data when generating the multi-value gradation value data 21 is the position indicated by “(2)” in FIG. 21, that is, the second position from the left in the upper stage of the pixels to which the same classification number is set. That is, here, as shown in FIG. 21, each of the classification numbers “1”, “2”, “33”, “34” is set to 8 pixels of 4 pixels (horizontal) × 2 pixels (vertical). When the dot formation data is generated based on the multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located second from the left in the middle upper stage, as shown in FIG. 20B. Execute how to cut out pixels. Here, pixel data “00” is acquired as dot formation data by such a cutout method.

  Also, as shown in FIG. 20C, the second pixel from the right in the upper stage among the eight pixels is cut out because the pixel referred to in the CMYK image data when generating the multi-value gradation value data 21 is the position indicated by “(3)” in FIG. 21, that is, the second position from the right on the upper stage in the pixels to which the same classification number is set. That is, here, as shown in FIG. 21, each of the classification numbers “1”, “2”, “33”, “34” is set to 8 pixels of 4 pixels (horizontal) × 2 pixels (vertical). When the dot formation data is generated based on the multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located second from the right in the upper middle part as shown in FIG. 20C. Execute how to cut out pixels. Here, pixel data “10” is acquired as dot formation data by such a cutting method.

  Also, as shown in FIG. 20D, the pixel located in the upper right corner of the eight pixels is cut out because the position of the pixel referred to in the CMYK image data when generating the multi-value gradation value data is This is the case where the pixel position indicated by “(4)” in FIG. 21, that is, the position of the upper right corner among the pixels to which the same classification number is set. That is, here, as shown in FIG. 21, each of the classification numbers “1”, “2”, “33”, “34” is set to 8 pixels of 4 pixels (horizontal) × 2 pixels (vertical). When generating dot formation data based on multi-value gradation value data obtained by multi-value processing of gradation values of pixels located in the upper right corner of the pixel, a method of clipping pixels as shown in FIG. 20D Execute. Here, pixel data “00” is acquired as dot formation data by such a cutout method.

  As shown in FIG. 20E, the pixel located in the lower left corner of the eight pixels is cut out because the position of the pixel referred to in the CMYK image data when generating multi-value gradation value data is shown in FIG. Is the position indicated by “(5)”, that is, the position of the upper left corner in the pixel to which the same classification number is set. That is, here, as shown in FIG. 21, eight pixels of 4 pixels (horizontal) × 2 pixels (vertical) in which the classification numbers “1”, “2”, “33”, and “34” are set respectively. When the dot formation data is generated based on the multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located in the lower left corner in the middle, the pixel extraction method as shown in FIG. 20E Execute. Here, pixel data “00” is acquired as dot formation data by such a cutout method.

  Also, as shown in FIG. 20F, the second pixel from the left in the lower stage among the eight pixels is cut out because the pixel referred to in the CMYK image data when generating the multi-value gradation value data 21 is the position indicated by “(6)” in FIG. 21, that is, the second position from the left in the lower row of the pixels to which the same classification number is set. That is, here, as shown in FIG. 21, each of the classification numbers “1”, “2”, “33”, “34” is set to 8 pixels of 4 pixels (horizontal) × 2 pixels (vertical). When the dot formation data is generated based on the multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located second from the left in the lower row in the middle as shown in FIG. Execute how to cut out pixels. Here, pixel data “01” is acquired as dot formation data by such a cutting method.

  Also, as shown in FIG. 20G, the second pixel from the right in the lower row among the eight pixels is cut out because the pixel referred to in the CMYK image data when generating multi-value gradation value data 21 is the position indicated by “(7)” in FIG. 21, that is, the second position from the lower right in the pixel to which the same classification number is set. That is, here, as shown in FIG. 21, eight pixels of 4 pixels (horizontal) × 2 pixels (vertical) in which the classification numbers “1”, “2”, “33”, and “34” are set respectively. When the dot formation data is generated based on the multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located second from the right in the lower stage in the middle, as shown in FIG. Execute how to cut out. Here, pixel data “00” is acquired as dot formation data by such a cutout method.

  Also, as shown in FIG. 20H, the pixel located in the lower right corner among the eight pixels is cut out because of the position in the pixel referred to in the CMYK image data when generating multi-value gradation value data. Is the position indicated by “(8)” in FIG. 21, that is, the position of the upper right corner in the pixels to which the same classification number is set. That is, here, as shown in FIG. 21, each of the classification numbers “1”, “2”, “33”, “34” is set to 8 pixels of 4 pixels (horizontal) × 2 pixels (vertical). When the dot formation data is generated based on the multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located in the lower right corner in the middle, the method of clipping the pixel as shown in FIG. Execute. Here, pixel data “10” is acquired as dot formation data by such a cutting method.

(2) In the case of 2 × 1 mode In the case of “2 × 1 mode”, the horizontal resolution (output resolution) when printing an image on the medium S is twice the resolution of CMYK image data. From this, in the “2 × 1 mode”, the pixels to be cut out are two pixels arranged in the horizontal direction among the eight pixels. FIG. 22 illustrates the positions of pixels cut out from the eight pixels. 22A to 22D respectively show the positions of pixels to be cut out. FIG. 23 illustrates the pixel positions in the CMYK image data.

  FIG. 22A illustrates the case where the first and second pixels from the left in the upper row of the eight pixels are cut out. FIG. 22B illustrates a case where the first and second pixels from the upper right in the eight pixels are cut out. FIG. 22C illustrates the case where the first and second pixels from the left in the lower row of the eight pixels are cut out. FIG. 22D illustrates a case where the first and second pixels are cut out from the lower right in the eight pixels.

  As shown in FIG. 22A, the first and second pixels from the left in the upper stage of the eight pixels are cut out because the pixels referred to in the CMYK image data when generating the multi-value gradation value data Is the position indicated by “(1)” in FIG. 23, that is, the position of the upper left corner of the pixels to which the same classification number is set. That is, here, as shown in FIG. 23, each of the four pixels of 2 pixels (horizontal) × 2 pixels (vertical) in which the classification numbers “1” to “4” and “33” to “36” are set, respectively. When generating dot formation data based on multi-value gradation value data obtained by multi-value processing of gradation values of pixels located in the upper left corner of the pixel, a method of clipping pixels as shown in FIG. 22A Execute. Here, two pixel data arranged in the horizontal direction “11” and “00” are acquired as dot formation data by such a cutting method.

  As illustrated in FIG. 22B, the first and second pixels from the right in the upper stage among the eight pixels are cut out because the pixels referred to in the CMYK image data when generating multi-value gradation value data Is the position indicated by “(2)” in FIG. 23, that is, the position of the upper right corner of the pixels to which the same classification number is set. That is, here, as shown in FIG. 23, each of the four pixels of 2 pixels (horizontal) × 2 pixels (vertical) in which the classification numbers “1” to “4” and “33” to “36” are set, respectively. When the dot formation data is generated based on the multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located in the upper right corner in the middle, the pixel cutting method as shown in FIG. 22B Execute. Here, two pixel data arranged in the horizontal direction of “10” and “00” are acquired as dot formation data by such a clipping method.

  As illustrated in FIG. 22C, the first and second pixels from the left in the lower stage among the eight pixels are cut out because the pixels referred to in the CMYK image data when generating the multi-value gradation value data Is the position indicated by “(3)” in FIG. 23, that is, the position of the lower left corner in the pixel to which the same classification number is set. That is, here, as shown in FIG. 23, each of the four pixels of 2 pixels (horizontal) × 2 pixels (vertical) in which the classification numbers “1” to “4” and “33” to “36” are set, respectively. When the dot formation data is generated based on the multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located in the lower left corner in the middle, the pixel extraction method as shown in FIG. 22C Execute. Here, two pixel data arranged in the horizontal direction “00” and “01” are acquired as dot formation data by such a cutting method.

  As shown in FIG. 22D, the first and second pixels from the lower right of the eight pixels are cut out from the pixels referred to in the CMYK image data when generating multi-value gradation value data. Is the position indicated by “(4)” in FIG. 23, that is, the position of the lower right corner of the pixels to which the same classification number is set. That is, here, as shown in FIG. 23, each of the four pixels of 2 pixels (horizontal) × 2 pixels (vertical) in which the classification numbers “1” to “4” and “33” to “36” are set, respectively. When the dot formation data is generated based on the multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located in the lower right corner in the middle, a method of clipping the pixel as shown in FIG. 22D Execute. Here, two pixel data arranged in the horizontal direction of “00” and “10” are acquired as dot formation data by such a clipping method.

(3) 1 × 2 Mode In the “1 × 2 mode”, the vertical resolution (output resolution) when printing an image on the medium S is twice the resolution of the CMYK image data. For this reason, the pixels cut out in the “1 × 2 mode” are two pixels arranged in the vertical direction among the eight pixels. FIG. 24 illustrates the positions of pixels cut out from the eight pixels. 24A to 24D respectively show the positions of the pixels to be cut out. FIG. 25 illustrates the pixel positions in the CMYK image data.

  FIG. 24A illustrates the case where two upper and lower pixels located in the first column from the left among the eight pixels are cut out. FIG. 24B illustrates a case where two upper and lower pixels located in the second column from the left among the eight pixels are cut out. FIG. 24C illustrates the case where two upper and lower pixels located in the second column from the right among the eight pixels are cut out. FIG. 24D illustrates a case where two upper and lower pixels located in the first column from the right among the eight pixels are cut out.

  As shown in FIG. 24A, the upper and lower two pixels located in the first column from the left among the eight pixels are cut out because the pixels referred to in the CMYK image data when generating the multi-value gradation value data Is the position indicated by “(1)” in FIG. 25, that is, the first position from the left in the pixels to which the same classification number is set. That is, here, as shown in FIG. 25, the respective classification numbers “1”, “2”, “33”, “34”, “65”, “66”, “97”, “98” are set. Dot formation based on multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located first from the left among four pixels of 4 pixels (horizontal) × 1 pixel (vertical) When generating data for use, a method of clipping pixels as shown in FIG. 24A is executed. Here, two pixel data arranged in the vertical direction of “11” and “00” are acquired as dot formation data by such a clipping method.

  As shown in FIG. 24B, the upper and lower two pixels located in the second column from the left among the eight pixels are cut out because the pixels referred to in the CMYK image data when generating the multi-value gradation value data Is the position indicated by “(2)” in FIG. 25, that is, the second position from the left in the pixels to which the same classification number is set. That is, here, as shown in FIG. 25, the respective classification numbers “1”, “2”, “33”, “34”, “65”, “66”, “97”, “98” are set. Dot formation based on multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located second from the left among four pixels of 4 pixels (horizontal) × 1 pixel (vertical) When generating data for use, a method of cutting out pixels as shown in FIG. 24B is executed. Here, two pixel data arranged in the vertical direction “00” and “01” are acquired as dot formation data by such a cutting method.

  As shown in FIG. 24C, the upper and lower two pixels located in the second column from the right among the eight pixels are cut out because the pixels referred to in the CMYK image data when generating the multi-value gradation value data Is the position indicated by “(3)” in FIG. 25, that is, the second position from the right in the pixels to which the same classification number is set. That is, here, as shown in FIG. 25, the respective classification numbers “1”, “2”, “33”, “34”, “65”, “66”, “97”, “98” are set. Dot formation based on multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located second from the right among four pixels of 4 pixels (horizontal) × 1 pixel (vertical) When generating data for use, a method of clipping pixels as shown in FIG. 24C is executed. Here, two pixel data arranged in the vertical direction of “10” and “00” are acquired as dot formation data by such a clipping method.

  As shown in FIG. 24D, the top and bottom two pixels located in the first column from the right among the eight pixels are cut out because the pixels referred to in the CMYK image data when generating the multi-value gradation value data Is the position indicated by “(4)” in FIG. 25, that is, the first position from the right in the pixels to which the same classification number is set. That is, here, as shown in FIG. 25, the respective classification numbers “1”, “2”, “33”, “34”, “65”, “66”, “97”, “98” are set. Dot formation based on multi-value gradation value data obtained by multi-value processing of the gradation value of the pixel located first from the right among four pixels of 4 pixels (horizontal) × 1 pixel (vertical) When generating data for use, a pixel clipping method as shown in FIG. 24D is executed. Here, two pixel data arranged in the vertical direction of “00” and “10” are acquired as dot formation data by such a cutting method.

(4) 2 × 2 mode In the “2 × 2 mode”, the horizontal and vertical resolutions (output resolutions) when printing an image on the medium S are each twice the resolution of the CMYK image data. Become. From this, in the “2 × 2 mode”, the number of pixels to be cut out is a total of four pixels, two pixels in the horizontal direction and two pixels in the vertical direction among the eight pixels. FIG. 26 illustrates the positions of pixels that are cut out from the eight pixels. FIG. 26A and FIG. 26B show the positions of the pixels to be cut out, respectively. FIG. 27 illustrates the positions of pixels in CMYK image data.

  As shown in FIG. 26A, the four pixels located on the left and right of the eight pixels are cut out because the positions of the pixels referenced in the CMYK image data when generating the multi-value gradation value data are as follows. This is the case indicated by “(1)” in FIG. 27, that is, the position on the left side of the pixels to which the same classification number is set. That is, here, as shown in FIG. 27, the respective classification numbers “1” to “4”, “33” to “37”, “65” to “68”, and “97” to “100” are set. Based on multi-value gradation value data obtained by multi-value processing of gradation values of pixels located on the left side of two pixels of 2 pixels (horizontal) × 1 pixel (vertical), dot formation data is obtained. In the case of generation, a pixel clipping method as shown in FIG. 26A is executed. Here, four pixel data arranged in the vertical direction and the horizontal direction of “11”, “00”, “00”, and “01” are acquired as dot formation data by such a clipping method.

  As shown in FIG. 26B, the four pixels located on the right side among the eight pixels are cut out from the top, bottom, left, and right. This is the case indicated by “(2)” in FIG. 27, that is, the position on the right side of the pixels to which the same classification number is set. That is, here, as shown in FIG. 27, the respective classification numbers “1” to “4”, “33” to “37”, “65” to “68”, and “97” to “100” are set. Based on multi-value gradation value data obtained by multi-value processing of gradation values of pixels located on the right side of two pixels of 2 pixels (horizontal) × 1 pixel (vertical), dot formation data is obtained. In the case of generation, a pixel clipping method as shown in FIG. 26B is executed. Here, four pixel data arranged in the vertical direction and the horizontal direction of “10”, “00”, “00”, and “10” are acquired as dot formation data by such a clipping method.

(5) In the case of 4 × 2 mode In the case of “4 × 2 mode”, the horizontal resolution (output resolution) when printing an image on the medium S is four times the resolution of the CMYK image data, and the medium The vertical resolution (output resolution) when printing an image on S is twice the resolution of the CMYK image data. For this reason, all eight pixels are extracted in the “4 × 2 mode”. FIG. 28 illustrates the positions of pixels that are cut out from the eight pixels. As shown in the figure, all eight pixels whose positions and sizes of dots to be formed are determined are cut out as dot formation data. That is, here, “11”, “00”, “10”, “00”, “00”, “01”, “00”, “10” are arranged in four horizontal directions and two in the vertical direction. Two pieces of pixel data are acquired as dot formation data.

<For other modes>
As described above, in the case of “1 × 1 mode”, “2 × 1 mode”, “1 × 2 mode”, “2 × 2 mode” and “4 × 2 mode”, the dot formation data is obtained by the method described above. Generate. However, in other modes, ie, “2 × 4 mode” and “4 × 4 mode”, dot formation data is generated by a method different from the method described above. The different methods will be described below.

(1) In the case of 2 × 4 mode In the case of “2 × 4 mode”, compared with the case of other modes described above. The process of converting multi-value gradation value data into dot number data is different. Here, the multi-value gradation value data is converted into dot number data by a dot number data conversion table for “2 × 4 mode” which is different from the dot number data conversion table described with reference to FIG.

  FIG. 29 conceptually illustrates an example of a dot number data conversion table for the “2 × 4 mode”. In this dot number data conversion table, similarly to the dot number data conversion table described with reference to FIG. 16, dot number data is set in association with each multi-value gradation value data for each classification number. Corresponding dot number data can be derived from "classification number" and "multi-value gradation value data". The “classification number” is represented by numbers “1” to “1024” as in the case of FIG. Also, “multi-value gradation value data” is represented by numerical values from “0” to “31” as in the case of FIG. Further, “dot number data” is represented by numerical values “0” to “164” as in the case of FIG. 16. The dot number data is individually prepared according to the classification numbers “1” to “1024” and the multi-value gradation value data “0” to “31”.

  Here, the “dot number data” is coded to indicate the size of each dot to be formed (ie, “small dot”, “medium dot”, “large dot”) in addition to the number of dots to be formed. It has become the data. Here, since the “dot number data” includes information on the number of dots formed for eight pixels, the numerical values “0” to “164” are used as in the case described with reference to FIG. It has come to be represented.

  In the present embodiment, data relating to the dot number data conversion table used in the “2 × 4 mode” is stored in the SDRAM 102 on the ASIC 95 side. The dot formation data generation unit 184 converts the acquired multi-value gradation value data into dot number data in the “2 × 4 mode”, and the “2 × 4 mode” stored in the SDRAM 102 on the ASIC 95 side. Refer to the data related to the dot count data conversion table.

  The data relating to the “2 × 4 mode” dot number data conversion table stored in the SDRAM 102 on the ASIC 95 side is stored in, for example, a non-volatile memory such as the ROM 92 mounted in the SPC multifunction apparatus 1 to form dots. When the data generating unit 184 converts the dot number data in the “2 × 4 mode”, it is read from a nonvolatile memory such as the ROM 92 and stored in the SDRAM 102 on the ASIC 95 side.

  In the “2 × 4 mode”, the dot formation data generation unit 184 refers to this dot number data conversion table and converts the multi-value gradation value data into dot number data. Then, the dot formation data generation unit 184 determines the presence or absence of dot formation individually for a total of 8 pixels, 2 horizontal pixels × 4 vertical pixels, based on the dot number data acquired by this conversion. At this time, the dot formation data generation unit 184 determines whether or not to form dots individually for the eight pixels based on the order value matrix prepared for the “2 × 4 mode”.

  FIG. 30A explains an example of the order value matrix used at this time. As shown in the figure, the order value matrix used in the “2 × 4 mode” is a number indicating the order in which dots should be formed for a total of eight pixels, two horizontal pixels and four vertical pixels (hereinafter, It is also a matrix in which “order value” is set. The numbers set for the eight pixels respectively represent the order in which dots should be formed, as in the order value matrix described with reference to FIG. That is, the pixel for which the order value “1” is set is the pixel in which a dot is to be formed first. A pixel for which the order value “2” is set is a pixel in which a dot is to be formed second. A pixel for which the order value “3” is set is a pixel in which a dot is to be formed third.

  Such an order value matrix is individually set for each classification number as in the order value matrix described with reference to FIG. 18 even in the “2 × 4 mode”. That is, the order value matrix is set to a different matrix for each classification number.

  In this embodiment, data relating to the order value matrix used in the “2 × 4 mode” is stored in the SDRAM 102 on the ASIC 95 side. When the dot formation data generation unit 184 decides whether or not to form dots for each of the eight pixels in the “2 × 4 mode” based on the acquired dot number data, the dot formation data generation unit 184 stores “ Reference is made to the information regarding the order value matrix of “2 × 4 mode”.

  Note that the information related to the “2 × 4 mode” order value matrix stored in the SDRAM 102 on the ASIC 95 side is stored in, for example, a non-volatile memory such as the ROM 92 mounted in the SPC multifunction apparatus 1, and the dot formation data When the generation unit 184 determines whether or not to form dots for each of the eight pixels in the “2 × 4 mode” based on the dot number data, the generation unit 184 reads out from the nonvolatile memory such as the ROM 92 and stores it in the SDRAM 102 on the ASIC 95 side. Stored.

  The method for determining the presence or absence of dot formation for each of the eight pixels based on such an order value matrix is the same method as described with reference to FIG. That is, first, the positions of the pixels to be formed are determined in order from the large-sized dots where the dots are easily noticeable.

  FIG. 30B conceptually illustrates an example of a procedure for determining whether or not to form dots for each of the eight pixels based on the dot number data and the order value matrix in the “2 × 4 mode”. Here, based on the dot number data indicating that one large dot, two medium dots, and one small dot should be formed, whether or not dots are formed using the sequence value matrix described in FIG. 30A This will be described by taking the case of determining the value as an example.

  Here, the pixel corresponding to the order value “1” is set to the largest dot, that is, the large dot (“11”). Since the number of large dots to be formed is one, a medium dot (“10”) is set to the pixel corresponding to the order value “2”. Since the number of medium dots to be formed is two, medium dots (“10”) are also set for the pixels corresponding to the order value “3”. Next, a small dot (“01”) is set to the pixel corresponding to the order value “4”. Since the number of small dots to be formed is one, no dots are formed in the remaining pixels, that is, the pixels corresponding to the order values “5” to “8”.

  In this way, in the “2 × 4 mode”, the dot formation data generation unit 184 performs dot formation for each of a total of 8 pixels, 2 horizontal pixels × 4 vertical pixels, based on the multi-value gradation value data. Determine presence or absence. Then, the dot formation data generation unit 184 uses all the eight pixels that have been determined for dot formation as dot formation data.

(2) In the case of the 4 × 4 mode In the case of the “4 × 4 mode”, the process for converting the multi-value gradation value data into the dot number data is different from that in the other modes described above. In the case of “4 × 4 mode”, as in the case of “2 × 4 mode”, the dot number data conversion table described in FIG. 16 and FIG. Use the dot count data conversion table.

  FIG. 31 conceptually illustrates an example of a dot number data conversion table for the “4 × 4 mode”. In this dot number data conversion table, similarly to the dot number data conversion table described with reference to FIGS. 16 and 29, dot number data is set in association with each multi-value gradation value data for each classification number. Accordingly, the corresponding dot number data can be derived from the “classification number” and the “multi-value gradation value data”. The “classification number” is represented by numbers “1” to “1024” as in the case of FIGS. Also, “multi-value gradation value data” is represented by numerical values from “0” to “31” as in the case of FIG. The dot number data is individually prepared according to the classification numbers “1” to “1024” and the multi-value gradation value data “0” to “31”.

However, “dot number data” is represented by numerical values “0” to “968”, unlike the cases of FIG. 16 and FIG. 29. The reason why the “dot number data” is set to take the values “0” to “968” as described above is as follows. That is, as described above, the dot number data is coded to indicate the size of each dot to be formed (that is, “small dot”, “medium dot”, “large dot”) in addition to the number of dots to be formed. It is the data that was made. In the “4 × 4 mode”, instead of determining whether or not dots are formed for the eight pixels based on the dot number data, 16 pixels (4 horizontal pixels × 4 vertical pixels) are not determined. The presence or absence of dot formation is determined. The maximum number of dots that can be formed for 16 pixels is 16. There are four possible states for each pixel: “large dot”, “medium dot”, “small dot”, and “no dot formation”, so the combination of the number of dots is ₄ H ₁₆ (= _{4 + 16-1).} C ₁₆ ) = 969. From this, all combinations can be expressed if the dot number data is represented by values of “0” to “968”.

  FIG. 32 illustrates an example of a correspondence relationship between the dot number data and information regarding the number and size of dots to be formed, which are represented by the dot number data. As described above, the dot number data takes values from “0” to “968”. The numerical values of “0” to “968” in the dot number data indicate the presence / absence of dot formation and the dot size, respectively.

  In the present embodiment, data relating to the dot number data conversion table used in the “4 × 4 mode” is stored in the SDRAM 102 on the ASIC 95 side. The dot formation data generation unit 184 converts the acquired multi-value gradation value data into dot number data in the “4 × 4 mode”, and the “4 × 4 mode” stored in the SDRAM 102 on the ASIC 95 side. The data related to the dot count data conversion table is referred to.

  The data related to the “4 × 4 mode” dot number data conversion table stored in the SDRAM 102 on the ASIC 95 side is stored in, for example, a non-volatile memory such as the ROM 92 mounted in the SPC multifunction apparatus 1 to form dots. When the data generation unit 184 converts the dot number data in the “4 × 4 mode”, it is read from a nonvolatile memory such as the ROM 92 and stored in the SDRAM 102 on the ASIC 95 side.

  In the “4 × 4 mode”, the dot formation data generation unit 184 refers to the dot number data conversion table and converts the multi-value gradation value data into dot number data. Then, the dot formation data generation unit 184 determines whether or not to form dots individually for a total of 16 pixels of 4 horizontal pixels × 4 vertical pixels based on the dot number data acquired by this conversion. At this time, the dot formation data generation unit 184 determines whether or not to form dots individually for 16 pixels based on the order value matrix prepared for the “4 × 4 mode”.

  FIG. 33A illustrates an example of the order value matrix used at this time. As shown in the figure, the order value matrix used in the “4 × 4 mode” is a number indicating the order in which dots should be formed for a total of 16 pixels, 4 pixels in the horizontal direction and 4 pixels in the vertical direction (hereinafter, It is also a matrix in which “order value” is set. The numbers set for the 16 pixels respectively represent the order in which dots should be formed, as in the order value matrix described with reference to FIGS. 18 and 30A. That is, the pixel for which the order value “1” is set is the pixel in which a dot is to be formed first. A pixel for which the order value “2” is set is a pixel in which a dot is to be formed second. A pixel for which the order value “3” is set is a pixel in which a dot is to be formed third.

  Such an order value matrix is individually set for each classification number as in the order value matrix described with reference to FIGS. 18 and 30A even in the “4 × 4 mode”. That is, the order value matrix is set to a different matrix for each classification number.

  In this embodiment, data relating to the order value matrix used in the “4 × 4 mode” is stored in the SDRAM 102 on the ASIC 95 side. When the dot formation data generation unit 184 determines whether or not to form dots for each of the 16 pixels in the “4 × 4 mode” based on the acquired dot number data, the dot formation data generation unit 184 stores “ Reference is made to the information related to the “4 × 4 mode” order value matrix.

  Note that the information regarding the “4 × 4 mode” order value matrix stored in the SDRAM 102 on the ASIC 95 side is stored in, for example, a non-volatile memory such as the ROM 92 mounted in the SPC multifunction apparatus 1, and the dot formation data. When the generation unit 184 determines whether or not to form dots for each of the 16 pixels in the “4 × 4 mode” based on the dot number data, the generation unit 184 reads out from the nonvolatile memory such as the ROM 92 and stores it in the SDRAM 102 on the ASIC 95 side. Stored.

  The method for determining the presence or absence of dot formation for each of the 16 pixels based on such an order value matrix is the same method as described with reference to FIG. That is, first, the positions of the pixels to be formed are determined in order from the large-sized dots where the dots are easily noticeable.

  FIG. 33B conceptually illustrates an example of a procedure for determining the presence or absence of dot formation for each of 16 pixels based on the dot number data and the order value matrix in the “4 × 4 mode”. Here, based on the dot number data indicating that six large dots, four medium dots, and one small dot should be formed, whether or not dots are formed using the sequence value matrix described in FIG. 33A This will be described by taking the case of determining the value as an example.

  Here, the pixel corresponding to the order value “1” is set to the largest dot, that is, the large dot (“11”). Since the number of large dots to be formed is 6, large dots (“11”) are also set in the pixels corresponding to the order values “2” to “6”. Next, a medium dot (“10”) is set to the pixel corresponding to the order value “7”. Since the number of medium dots to be formed is 4, medium dots (“10”) are also set for the pixels corresponding to the order values “8” to “10”. Next, a small dot (“01”) is set to the pixel corresponding to the order value “11”. Since the number of small dots to be formed is one, no dot is formed in the remaining pixels, that is, the pixels corresponding to the order values “12” to “16”.

  In this way, in the “4 × 4 mode”, the dot formation data generation unit 184 performs dot formation for each of a total of 16 pixels of 4 horizontal pixels × 4 vertical pixels based on the multi-value gradation value data. Determine presence or absence. Then, the dot formation data generation unit 184 uses all the 16 pixels for which dot formation has been determined as dot formation data.

<Process actually executed>
The dot formation data generation unit 184 generates dot formation data for an image to be printed, one raster line at a time, based on the multi-value gradation value data generated by the multi-value processing unit. FIG. 34 schematically illustrates an image of processing performed at this time. The dot formation data generation unit 184 acquires multilevel tone value data corresponding to one raster line from the multilevel tone value data stored in the multilevel tone value data buffer 188. Then, based on the acquired multi-value gradation value data, dot formation data for one raster line is generated. That is, for example, first, when forming dot formation data for the first raster line M1 shown in the figure, the dot formation data generation unit 184 uses the multivalue corresponding to the first raster line M1. The gradation value data is acquired from the multi-value gradation value data buffer 188. When generating dot formation data for the raster line M2 in the second row, the dot formation data generation unit 184 converts the multi-value gradation value data corresponding to the raster line M2 in the second row into multivalued data. Obtained from the gradation value data buffer 188. Further, when generating the dot formation data for the raster line M3 in the third row, the dot formation data generation unit 184 converts the multi-value gradation value data corresponding to the raster line M3 in the third row into the multi-value. Obtained from the gradation value data buffer 188. In this way, the dot formation data generation unit 184 generates dot formation data for each raster line.

  FIG. 35A to FIG. 35G respectively explain an example of a method for generating dot formation data in each mode. FIG. 35A illustrates an example of the “1 × 1 mode”. FIG. 35B illustrates an example of the “2 × 1 mode”. FIG. 35C illustrates an example of the “1 × 2 mode”. FIG. 35D illustrates an example of the “2 × 2 mode”. FIG. 35E illustrates an example of the “4 × 2 mode”. FIG. 35F illustrates an example of the “2 × 4 mode”. FIG. 35G illustrates an example of the “4 × 4 mode”.

(1) In the case of 1 × 1 mode In the case of “1 × 1 mode”, as described in FIG. 20, data of one pixel is cut out from eight pixels. The dot formation data generation unit 184 uses the data of one pixel cut out in this way as it is as the data of the pixels constituting one raster line. That is, as will be described with reference to FIG. 35A, when the dot formation data generation unit 184 generates, for example, the raster line M1 of the first row, data of one pixel cut out (here, “11”). (Large dot data) is used as it is as the data of the pixels constituting the raster line M1. In this way, the multi-value gradation value data corresponding to the raster line M1 in the first row is sequentially obtained from the multi-value gradation value data buffer 188, and the dot formation data for the raster line M1 in the first row is generated. To do.

  Similarly for the other raster lines M2, M3, M4, and M5, the data of one pixel cut out from the eight pixels is used as the data of the pixels constituting each raster line M2, M3, M4, and M5. Data for dot formation for each raster line M2, M3, M4, and M5 is generated.

(2) In the case of 2 × 1 mode In the case of “2 × 1 mode”, as described with reference to FIG. Data of two pixels arranged side by side are cut out. The dot formation data generation unit 184 uses the data of the two pixels cut out in this way as data of the pixels constituting one raster line. That is, as will be described with reference to FIG. 35B, when the dot formation data generation unit 184 generates, for example, the raster line M1 of the first row, data of two pixels extracted (here, “10”). (Medium dot) and “01” (small dot)) are used as they are as the data of the pixels constituting the raster line M1. That is, data of two pixels (“10” and “01”) are pasted as data of pixels constituting the raster line M1 in a state where they are arranged side by side. In this way, the multi-value gradation value data corresponding to the first raster line M1 is sequentially obtained from the value gradation value data buffer 188, and the dot formation data for the first raster line M1 is generated. .

  Similarly for the other raster lines M2, M3, M4 and M5, the data of two pixels cut out from the eight pixels are used as the data of the pixels constituting each raster line M2, M3, M4 and M5. The dot formation data for each raster line M2, M3, M4, M5 is generated.

(3) In the case of 1 × 2 mode In the case of “1 × 2 mode”, as described in FIG. 24, a total of 2 pixels of 1 horizontal × 2 vertical are cut out from 8 pixels. It is. When pixels arranged in the vertical direction are cut out in this way, the dot formation data generation unit 184 uses the data of the cut out two pixels as data of pixels constituting different raster lines. That is, when the data of one of the cut out two pixels is used as the data of the pixels constituting a raster line, the data of the other pixel is different from the raster line. Is used as pixel data. For example, as will be described with reference to FIG. 35C, when the dot formation data generation unit 184 generates the raster line M1 in the first row, the data of the pixel located in the upper stage of the two pixels arranged in the vertical direction. (Here, “10” (medium dot)) is used as data of the pixels constituting the first raster line M1. On the other hand, when the dot formation data generation unit 184 generates the raster line M2 of the second row, the pixel data (here “01” ( Small dots)) are used as data of the pixels constituting the raster line M2 in the second row. In this way, the two raster lines M1 and M2 are respectively generated by pixels cut out corresponding to the same multi-value gradation value data.

  Similarly, the other raster lines M3 and M4 are generated by pixels cut out corresponding to the same multi-value gradation value data.

(4) In the case of 2 × 2 mode In the case of “2 × 2 mode”, as described in FIG. 26, a total of 4 pixels of 2 horizontal pixels × 2 vertical pixels are cut out from 8 pixels. It is. The four pixels cut out here are used as dot formation data for two different raster lines because there are two pixels arranged in the vertical direction. That is, as will be described with reference to FIG. 35D, when the dot formation data generation unit 184 generates the raster line M1 in the first row, for example, two pixels located in the upper stage among the four pixels Data (here, “11” (large dot) and “01” (small dot)) are used as data of the pixels constituting the first raster line M1. On the other hand, when the dot formation data generation unit 184 generates the raster line M2 of the second row, of the four pixels, two pixels (here “00” (no dot formation) ) And “10” (medium dot)) are used as data of pixels constituting the raster line M2 in the second row. In this way, the two raster lines M1 and M2 are sequentially generated from the same multi-value gradation value data.

  Similarly, the other raster lines M3 and M4 are sequentially generated by four pixels cut out corresponding to the same multi-value gradation value data.

(5) In the case of 4 × 2 mode In the case of “4 × 2 mode”, as described in FIG. 28, all eight pixels are cut out. Even in this case, since the cut out eight pixels include pixels arranged in the vertical direction, they are used as dot formation data for two or more different raster lines. That is, as will be described with reference to FIG. 35E, when the dot formation data generation unit 184 generates the raster line M1 in the first row, for example, four pixels located in the upper stage among the eight pixels. (Here, “11” (large dot), “00” (no dot formation), “10” (medium dot), and “00” (no dot formation)) constitute the first raster line M1. Used as pixel data. On the other hand, when the dot formation data generation unit 184 generates the raster line M2 of the second row, of the 8 pixels, four pixels (here, “00” (no dot formation) ), “01” (small dot), “00” (no dot formation) and “10” (medium dot)) are used as data of the pixels constituting the raster line M2 of the second row. In this way, the two raster lines M1 and M2 are sequentially generated from the same multi-value gradation value data.

  Similarly, the other raster lines M3 and M4 are generated by pixels cut out corresponding to the same multi-value gradation value data.

(6) Case of 2 × 4 Mode In the case of “2 × 4 mode”, a total of 8 pixels of 2 horizontal pixels × 4 vertical pixels are cut out as described in FIG. 30B. The eight pixels cut out here also have four pixels arranged in the vertical direction, and are therefore used as dot formation data for four different raster lines. That is, as will be described with reference to FIG. 35F, when the dot formation data generation unit 184 generates the raster line M1 in the first row, for example, it is arranged in the first row from the top among the eight pixels. Data of two pixels (here, “00” (no dot formation) and “11” (large dot)) are used as data of the pixels constituting the first raster line M1. When the dot formation data generation unit 184 generates the raster line M2 of the second row, data of two pixels arranged in the second row from the top among the eight pixels (here, “01 ] (Small dot) and "00" (no dot formation)) are used as data of pixels constituting the raster line M2 of the second row. When the dot formation data generation unit 184 generates the raster line M3 in the third row, data of two pixels arranged in the third row from the top among the eight pixels (here, “10 ] (Medium dot) and "00" (no dot formation)) are used as data of the pixels constituting the third raster line M3. In addition, when the dot formation data generation unit 184 generates the raster line M4 in the fourth row, the data of two pixels arranged in the lowest row among the eight pixels (here, “00” (dot No formation) and “10” (medium dot)) are used as the data of the pixels constituting the fourth raster line M4. In this way, the four raster lines M1, M2, M3, and M4 are sequentially generated from the same multi-value gradation value data.

(7) In the case of 4 × 4 mode In the case of “4 × 4 mode”, as described in FIG. 33B, all 16 pixels are cut out. Since the 16 pixels cut out here include pixels arranged in the vertical direction, they are used as dot formation data for four different raster lines. That is, as will be described with reference to FIG. 35G, when the dot formation data generation unit 184 generates the raster line M1 of the first row, for example, it is arranged in the first row from the top among the 16 pixels. The data of four pixels (here, “11” (large dot), “00” (no dot formation), “11” (large dot) and “10” (medium dot)) constitute the raster line M1. Used as pixel data. When the dot formation data generation unit 184 generates the raster line M2 of the second row, data of four pixels arranged in the second row from the top among the 16 pixels (here, “11 ”(Large dot),“ 01 ”(small dot),“ 11 ”(large dot), and“ 01 ”(small dot)) are used as data of the pixels constituting the raster line M2. When the dot formation data generation unit 184 generates the raster line M3 of the third row, data of four pixels arranged in the third row from the top (in this case, “00” ”(No dot formation),“ 10 ”(medium dot),“ 00 ”(no dot formation) and“ 11 ”(large dot)) are used as data of the pixels constituting the raster line M3. Further, when the dot formation data generation unit 184 generates the fourth raster line M4, the data of the four pixels arranged in the lowermost row (here, “00” (no dot formation), “10”). (Medium dot), “00” (no dot formation) and “11” (large dot)) are used as data of the pixels constituting the raster line M4. In this way, the four raster lines M1, M2, M3, and M4 are sequentially generated from the same multi-value gradation value data.

<Raster line generation order>
Note that the generation order of each raster line of the dot formation data is not necessarily generated sequentially from the first raster line to the second, third, and fourth lines. That is, after the first raster line is generated by the dot formation data generation unit, the third raster line may be generated next, or the fourth raster line may be generated. This is related to the transmission order of the head drive data to the head 21. That is, the dot formation data generation unit 184 sequentially generates the raster lines corresponding to the head drive data to be transmitted to the head 21 first. On the other hand, the raster line corresponding to the head drive data transmitted later to the head 21 is generated later by the dot formation data generation unit 184.

  The dot formation data generation unit 184 acquires multi-value gradation value data from the multi-value gradation value data buffer 188 every time each raster line is generated, and uses the acquired multi-value gradation value data as dot number data. And determining whether or not to form dots individually for one or more pixels based on the dot number data, and data for at least some of the one or more pixels is used as data for pixels constituting a raster line. Used as

Therefore, in the case of “1 × 2 mode”, “2 × 2 mode”, “4 × 2 mode”, “2 × 4 mode”, and “4 × 4 mode”, the dot formation data generation unit 184 Each time each raster line is generated, the same multi-value gradation value data is obtained twice or more from the multi-value gradation value data buffer 188, and the data of the pixels constituting the raster line is obtained.
The raster line generation order by the dot formation data generation unit 184 will be described in detail later.

<Dot formation data buffer>
The data of each raster line of the dot formation data generated by the dot formation data generation unit 184 is temporarily stored in the dot formation data buffer 190 provided in the ASIC SDRAM 102 before being sent to the image buffer unit 112. Is done. The dot formation data buffer 190 stores the dot formation data generated by the dot formation data generation unit for two or more raster lines.
The image buffer unit 112 sequentially reads the dot formation data stored in the dot formation data buffer 190 one raster line at a time and stores it in the image buffers 126 and 127 as head drive data.
The head drive data stored in the image buffers 126 and 127 is read into the CPU 90 via the bus controller 114 and transferred to the head control unit 116 by the CPU 90. The head drive data transferred to the head control unit 116 is sequentially sent to the head 21 and printing processing is executed.

=== SDRAM area allocation ===
A data storage area in the SDRAM 102 for the ASIC 95 will be described. FIG. 36 explains the allocation status of the data storage area of the SDRAM 102. The data storage area of the SDRAM 102 includes an area 102A in which the line buffer 120 is provided, an area 102B in which a lookup table 136 (LUT) is stored, an area 102C in which a multi-level table is stored, and a dot number data conversion table. 102D, an area 102E in which data relating to the order value matrix is stored, an area 102F in which the multi-value gradation value data buffer 188 is set, and an area 102G in which the dot formation data buffer 190 is set An area 102H in which the image buffers 126 and 127 are set and an area 102I in which other data is stored are provided.

  In the area 102D, as a dot number data conversion table, a dot number data conversion table used in “1 × 1 mode” to “4 × 2 mode” and a dot number used in “2 × 4 mode” are displayed. A data conversion table and a dot number data conversion table used in the “4 × 4 mode” are stored. Further, in the area 102E, as data related to the order value matrix, data related to the order value matrix used in “1 × 1 mode” to “4 × 2 mode” and data used in “2 × 4 mode” are used. Data relating to the order value matrix and data relating to the order value matrix used in the “4 × 4 mode” are stored.

  Here, in the area 102F where the multi-value gradation value data buffer 188 is set, an image (second image) in which the multi-value gradation value data stored in the multi-value gradation value data buffer 188 is printed on the medium S is displayed. Since the data has a predetermined number of bits that does not depend on the resolution of the image, it can be made constant regardless of the resolution of the image (second image) printed on the medium S. Thereby, when printing an image on the medium S at a high resolution, the size of the multi-value gradation value data buffer 188 that must be secured on the SDRAM 102 can be greatly reduced. In addition, the number of accesses to the SDRAM 102 can be suppressed.

=== Configuration of Dot Formation Data Generation Unit ===
The configuration of the dot formation data generation unit 184 according to this embodiment will be described.
FIG. 37 illustrates an example of the configuration of the dot formation data generation unit 184. The dot formation data generation unit 184 includes a generation circuit 400, a first buffer 402, a second buffer 404, a third buffer 406, and a controller 414, as shown in FIG. The first buffer 402, the second buffer 404, and the third buffer 406 are configured by SRAM or the like.

  The generation circuit 400 converts the multi-value gradation value data acquired from the multi-value gradation value data buffer 188 provided in the SDRAM 102 of the ASIC 95 into dot number data, and is printed on the medium S based on the dot number data. Data for dot formation of the image (second image) is sequentially generated. Then, the generation circuit 400 sequentially stores the generated dot formation data in a dot formation data buffer 190 provided in the SDRAM 102 of the ASIC 95.

  On the other hand, a part of the dot number data conversion table 410 stored in the SDRAM 102 of the ASIC 95 is read from the SDRAM 102 and stored in the first buffer 402. The generation circuit 400 refers to a part of the dot number data conversion table 410 stored in the first buffer 402. Accordingly, the generation circuit 400 converts the multi-value gradation value data acquired from the multi-value gradation value data buffer 188 into dot number data.

  Further, in the second buffer 404, a part of the order value matrix 412 stored in the SDRAM 102 of the ASIC 95 is read from the SDRAM 102 and stored. The generation circuit 400 determines the presence or absence of dot formation for each of a plurality of pixels based on a part of the sequential value matrix data stored in the second buffer 404 and the dot number data obtained by the conversion. Here, the generation circuit 400 determines not only the presence / absence of dot formation but also the size of dots to be formed.

  Then, the generation circuit 400 stores the dot data of a plurality of pixels (here, 8 pixels or 16 pixels) for which the presence / absence of dot formation is determined in the third buffer 406. In the third buffer, large dots (here, “11”) or medium dots (here, “10”) are formed for a plurality of pixels (here, 8 pixels or 16 pixels). Whether to form a small dot (here “01”) or not form a dot (here “00”) is stored.

  The generation circuit 400 will be described with reference to FIGS. 20 to 28, FIG. 30B, and FIG. As described above, at least some of the pixels, that is, some or all of the pixels are cut out, and the cut out pixels are output as pixels for dot formation data of an image to be printed. The generation circuit 400 stores the output dot formation data in a dot formation data buffer 190 provided in the SDRAM 102 of the ASIC 95.

  On the other hand, the controller 414 comprehensively controls the generation circuit 400, the first buffer 402, the second buffer 404, and the third buffer 406. Here, the controller 414 instructs the multi-value gradation value data to be acquired from the multi-value gradation value data buffer 188 of the SDRAM 102 by the generation circuit 400, and the dots on the SDRAM 102 to be stored by the first buffer 402. A part of data in the number data conversion table 410 is instructed, or a part of data in the order value matrix 412 on the SDRAM 102 to be stored in the second buffer 404 is instructed. That is, the controller 414 functions as a “decode controller” in the present embodiment.

=== Generation of dot formation data ===
The dot formation data generation unit 184 generates dot formation data in order from data corresponding to head drive data to be transmitted to the head 21 first. That is, the dot formation data corresponding to the head drive data transmitted later to the head 21 is generated later.

(1) In the case of 4 × 4 mode (1440 dpi (horizontal) × 1440 dpi (vertical))
FIG. 38 illustrates an example of dot formation data generation processing by the dot formation data generation unit 184. Here, a case where the dot formation data generation unit 184 generates dot formation data in the 4 × 4 mode will be described as an example. The resolution of the original image data, that is, the CMYK image data used to generate the multi-value gradation value data is 360 dpi (horizontal) × 360 dpi (vertical), and the resolution is 1440 dpi (horizontal) × 1440 dpi (vertical). Is printed. If the nozzle spacing (nozzle pitch, “k · D” in FIG. 7A) of the nozzles # 1 to # 180 of each nozzle row 211C, 211M, 211Y, 211K is 120 dpi (1/120 inch), the head drive data Corresponding dot formation data is generated as follows.

  As shown on the left side of the figure, the dot formation data is composed of pixels set at an interval of 1440 dpi (1/1440 inch) in the horizontal direction and an interval of 1440 dpi (1/1440 inch) in the vertical direction. The Here, the dot formation data generation unit 184 has the fourth line from the top, that is, the data corresponding to the first pixel from the left of “3Line” (the pixel indicated by gray in the drawing), and the fourth line from the top. Assume that data corresponding to the fifth pixel from the left of “3Line” (pixels indicated by gray in the drawing) is generated. These two pixels are pixels corresponding to one of the nozzles # 1 to # 180. In order to generate data corresponding to these two pixels, the dot formation data generation unit 184 needs to acquire multi-value gradation value data corresponding to these two pixels.

  An image of a block of 4 horizontal pixels × 4 vertical pixels corresponding to these two pixels is shown in the center of the figure. Of these two pixels, the block to which the first pixel from the left of “3Line” belongs is a block located at the upper left corner in the figure. In addition, the block to which the fifth pixel from the left of “3Line” belongs is a block located at the upper right corner in the drawing. These two pixels are located in the lower left corner of each block. In other words, when generating dot formation data corresponding to these two pixels, it is necessary to determine whether or not dots are formed for a total of 16 pixels, 4 pixels in the horizontal direction and 4 pixels in the vertical direction, corresponding to each block. . Then, it is necessary to extract the data corresponding to the pixel located at the lower left corner from the 4 horizontal pixels × 4 vertical pixels and 16 pixels in which the presence / absence of dot formation is determined, as dot formation data. In order to determine the presence / absence of dot formation for a total of 16 pixels (4 horizontal pixels × 4 vertical pixels) corresponding to each block, the dot formation data generation unit 184 generates multi-value gradation value data corresponding to each block. Must get.

  Here, the multi-value gradation value data that the dot formation data generation unit 184 needs to acquire is the position corresponding to the block to which the two pixels belong, that is, 1 from the top, as shown on the right side of FIG. This is the data corresponding to “Address 1” (data shown in gray in the figure). The dot formation data generation unit 184 acquires these two multi-value gradation value data, and generates data corresponding to the two pixels as dot formation data.

  Next, the dot formation data generation unit 184 has the 16th line from the top, that is, here, the data corresponding to the first pixel from the left of “15Line” (the pixel indicated by gray in the drawing) and the 16th line from the top. In other words, here, it is assumed that data corresponding to the fifth pixel from the left of “15Line” (the pixel indicated by gray in the drawing) is generated. These two pixels are pixels that should be generated by the nozzle located next to the nozzle corresponding to the two pixels of “3Line”. That is, for example, when the nozzle corresponding to the two pixels “3Line” is the nozzle # 1, the two pixels “15Line” correspond to the nozzle # 2. The interval between the two pixels of “3 Line” and the two pixels of “15 Line” corresponds to a nozzle interval (nozzle pitch), that is, 120 dpi (1/120 inch).

  The image of a block of 4 horizontal pixels × 4 vertical pixels corresponding to these two pixels is two blocks arranged in the fourth row from the top as shown in the center of the figure. Further, as shown on the right side of the figure, the multi-value gradation value data corresponding to these two blocks is the data in the fourth row from the top, that is, the data corresponding to “Address 4” (data shown in gray in the figure). ) Corresponds to two pixels, ie, the first pixel from the left of “15Line” (pixel shown in gray in the figure) and the fifth pixel from the left of “15Line” (pixel shown in gray in the figure). When the data to be generated is generated as dot formation data, the dot formation data generation unit 184 generates multi-value gradation value data corresponding to these two pixels, that is, data corresponding to “Address4” (in FIG. Based on these two multi-value gradation value data, the presence / absence of dot formation is determined for a total of 16 pixels (4 horizontal pixels × 4 vertical pixels). Then, the dot formation data generation unit 184 extracts data corresponding to the pixel located at the lower left corner from the 16 pixels and outputs it as dot formation data.

  In this way, the dot formation data generation unit 184 generates dot formation data in order from the data corresponding to the head drive data to be transmitted to the head 21 first. The dot formation data generation unit 184 generates data corresponding to other remaining pixels on the left side in the drawing at another timing.

(2) In the case of 4 × 2 mode (1440 dpi (horizontal) × 720 dpi (vertical))
FIG. 39 illustrates another example of dot formation data generation processing by the dot formation data generation unit 184. Here, a case where the dot formation data generation unit 184 generates dot formation data in the 4 × 2 mode will be described as an example. The resolution of the original image data, that is, the CMYK image data used to generate the multi-value gradation value data is 360 dpi (horizontal) × 360 dpi (vertical), and the image has a resolution of 1440 dpi (horizontal) × 720 dpi (vertical). Is printed. If the nozzle spacing (nozzle pitch, “k · D” in FIG. 7A) of the nozzles # 1 to # 180 of each nozzle row 211C, 211M, 211Y, 211K is 120 dpi (1/120 inch), the head drive data Corresponding dot formation data is generated as follows.

  As shown on the left side of the figure, the dot formation data is composed of pixels set at an interval of 1440 dpi (1/1440 inch) in the horizontal direction and an interval of 720 dpi (1/720 inch) in the vertical direction. The Here, the dot formation data generating unit 184 has the second line from the top, that is, the data corresponding to the first pixel from the left of “1Line” (here, the pixel indicated by gray in the figure), and the second line from the top. That is, here, it is assumed that data corresponding to the fifth pixel from the left of “1Line” (pixel shown in gray in the drawing) is generated. These two pixels are pixels corresponding to one of the nozzles # 1 to # 180. In order to generate data corresponding to these two pixels, the dot formation data generation unit 184 acquires multi-value gradation value data corresponding to these two pixels.

  An image of a block of 4 horizontal pixels × 2 vertical pixels corresponding to these two pixels is shown in the center of the figure. Of these two pixels, the block to which the first pixel from the left of “1Line” belongs is the block located at the upper left corner in the figure. In addition, the block to which the fifth pixel from the left of “1Line” belongs is a block located at the upper right corner in the drawing. These two pixels are located in the lower left corner of each block. In other words, when generating dot formation data corresponding to these two pixels, it is necessary to determine whether or not dots are formed for a total of 8 pixels, 4 horizontal pixels × 2 vertical pixels, corresponding to each block. . Then, it is necessary to extract data corresponding to the pixel located at the lower left corner from the 4 horizontal pixels × 2 vertical pixels and 8 pixels determined to have dot formation, as dot formation data. In order to determine the presence / absence of dot formation for a total of 8 pixels (4 horizontal pixels × 2 vertical pixels) corresponding to each block, the dot formation data generation unit 184 generates multi-value gradation value data corresponding to each block. Must get.

  Here, the multi-value gradation value data that the dot formation data generation unit 184 needs to acquire is the position corresponding to the block to which the two pixels belong, that is, 1 from the top, as shown on the right side of FIG. This is the data corresponding to “Address 1” (data shown in gray in the figure). The dot formation data generation unit 184 acquires these two multi-value gradation value data, and generates data corresponding to the two pixels as dot formation data.

  Next, the dot formation data generation unit 184 is the 8th line from the top, that is, here, the data corresponding to the first pixel from the left of “7Line” (the pixel indicated by gray in the figure) and the 8th line from the top. That is, here, it is assumed that data corresponding to the fifth pixel from the left of “7Line” (the pixel indicated by gray in the drawing) is generated. These two pixels are pixels that should be generated by a nozzle located next to the nozzle corresponding to the two pixels of “1Line”. That is, for example, when the nozzle corresponding to the previous two pixels “1 Line” is the nozzle # 1, the two pixels “7 Line” correspond to the nozzle # 2. The interval between the two pixels “1 Line” and the two pixels “7 Line” corresponds to a nozzle interval (nozzle pitch), that is, 120 dpi (1/120 inch).

  The image of a block of horizontal 4 pixels × vertical 2 pixels corresponding to these two pixels is two blocks arranged in the fourth row from the top as shown in the center of the figure. Further, as shown on the right side of the figure, the multi-value gradation value data corresponding to these two blocks is the data in the fourth row from the top, that is, the data corresponding to “Address 4” (data shown in gray in the figure). ) Corresponds to two pixels, ie, the first pixel from the left of “7Line” (pixel shown in gray in the figure) and the fifth pixel from the left of “7Line” (pixel shown in gray in the figure). When the data to be generated is generated as dot formation data, the dot formation data generation unit 184 generates multi-value gradation value data corresponding to these two pixels, that is, data corresponding to “Address4” (in FIG. Based on these two multi-value gradation value data, the presence / absence of dot formation is determined for a total of 8 pixels (4 horizontal pixels × 2 vertical pixels). Then, the dot formation data generation unit 184 extracts data corresponding to the pixel located at the lower left corner from the eight pixels and outputs it as dot formation data.

  In this way, the dot formation data generation unit 184 generates dot formation data in order from the data corresponding to the head drive data to be transmitted to the head 21 first. The dot formation data generation unit 184 generates data corresponding to other remaining pixels on the left side in the drawing at another timing.

(3) In the case of 2 × 1 mode (720 dpi (horizontal) × 360 dpi (vertical))
FIG. 40 illustrates another example of dot formation data generation processing by the dot formation data generation unit 184. Here, a case where the dot formation data generation unit 184 generates dot formation data in the 2 × 1 mode will be described as an example. The resolution of the original image data, that is, the CMYK image data used to generate the multi-value gradation value data is 360 dpi (horizontal) × 360 dpi (vertical), and the image has a resolution of 720 dpi (horizontal) × 360 dpi (vertical). Is printed. If the nozzle spacing (nozzle pitch, “k · D” in FIG. 7A) of the nozzles # 1 to # 180 of each nozzle row 211C, 211M, 211Y, 211K is 120 dpi (1/120 inch), the head drive data Corresponding dot formation data is generated as follows.

  As shown on the left side of the figure, the dot formation data is composed of pixels set at an interval of 720 dpi (1/720 inch) in the horizontal direction and an interval of 360 dpi (1/360 inch) in the vertical direction. The Here, the dot formation data generating unit 184 has the first line from the top, that is, the data corresponding to the first pixel from the left of “0Line” (the pixel indicated by gray in the figure), and the first line from the top. That is, here, it is assumed that data corresponding to the third pixel from the left of “0Line” (the pixel indicated by gray in the drawing) is generated. These two pixels are pixels corresponding to one of the nozzles # 1 to # 180. In order to generate data corresponding to these two pixels, the dot formation data generation unit 184 acquires multi-value gradation value data corresponding to these two pixels.

  The image of the block to which these two pixels correspond is shown in the center of the figure. In the case of “2 × 1 mode”, as described with reference to FIG. 22 above, data for pixels at predetermined positions is cut out from a block of 8 pixels in total of 4 horizontal pixels × 2 vertical pixels for dot formation. Data is generated. Of the two pixels, the position of the pixel in the block corresponding to the first pixel from the left of “0Line” is the upper left corner in the figure. In other words, when data corresponding to the first pixel from the left of “0Line” is generated, the data of the pixel located at the upper left corner among the total of 8 pixels of 4 horizontal pixels × 2 vertical pixels is used for dot formation. It will be cut out as data. On the other hand, the position of the pixel in the block corresponding to the third pixel from the left of “0Line” is the second from the right in the upper part of the drawing. In other words, when data corresponding to the third pixel from the left of “0Line” is generated, the data of the pixel located second from the right in the upper row out of a total of 8 pixels, 4 horizontal pixels × 2 vertical pixels. It is cut out as dot formation data.

  When generating data corresponding to these two pixels, the dot formation data generation unit 184 acquires the multi-value gradation value data corresponding to these two pixels, and based on each multi-value gradation value data. Whether or not dots are formed must be determined for each of 4 pixels in the horizontal direction and 2 pixels in the vertical direction, for a total of 8 pixels. The multi-value gradation value data that the dot formation data generation unit 184 needs to acquire is the position corresponding to the block to which the two pixels belong, that is, the first row from the top, as shown on the right side of FIG. Data, that is, data corresponding to “Address1” (data shown in gray in the figure). The dot formation data generation unit 184 obtains these two multi-value gradation value data, and determines whether or not dots are formed for each of 4 pixels in the horizontal direction × 2 pixels in the vertical direction, for a total of 8 pixels, and is thus determined. Data of a pixel at a predetermined position is cut out from each of the eight pixels and generated as dot formation data.

  Next, the dot formation data generation unit 184 has the fourth line from the top, that is, the data corresponding to the first pixel from the left of “3Line” (the pixel indicated by gray in the figure), and the fourth line from the top. That is, here, it is assumed that data corresponding to the third pixel from the left of “3Line” (the pixel indicated by gray in the drawing) is generated. These two pixels are pixels that should be generated by a nozzle located next to the nozzle corresponding to the two pixels of “0Line”. That is, for example, when the nozzle corresponding to the previous two pixels “0Line” is the nozzle # 1, the two pixels “3Line” correspond to the nozzle # 2. The interval between the two pixels of “0Line” and the two pixels of “3Line” corresponds to a nozzle interval (nozzle pitch), that is, 120 dpi (1/120 inch).

  The image of the block to which these two pixels correspond is shown in the center of the figure. In the case of “2 × 1 mode”, as described with reference to FIG. 22 above, data for pixels at predetermined positions is cut out from a block of 8 pixels in total of 4 horizontal pixels × 2 vertical pixels for dot formation. Data is generated. Of the two pixels, the position of the pixel in the block corresponding to the first pixel from the left of “3Line” is the lower left corner in the figure. In other words, when data corresponding to the first pixel from the left of “3Line” is generated, the data of the pixel located at the lower left corner out of a total of 8 pixels of 4 horizontal pixels × 2 vertical pixels is used for dot formation. It will be cut out as data. On the other hand, the position of the pixel in the block corresponding to the third pixel from the left of “3Line” is the second from the right in the lower part of the figure. In other words, when data corresponding to the third pixel from the left of “0Line” is generated, the data of the pixel located second from the right in the lower row out of a total of 8 pixels (4 horizontal pixels × 2 vertical pixels). It is cut out as dot formation data.

  When generating data corresponding to these two pixels, the dot formation data generation unit 184 acquires the multi-value gradation value data corresponding to these two pixels, and based on each multi-value gradation value data. Whether or not dots are formed is determined for a total of 8 pixels, 4 pixels horizontally × 2 pixels vertically. As shown on the right side of the figure, the multi-value gradation value data acquired here is the data in the fourth row from the top, that is, data corresponding to “Address 4” (data shown in gray in the figure). Become. The dot formation data generation unit 184 obtains these two multi-value gradation value data, and determines whether or not dots are formed for each of 4 pixels in the horizontal direction × 2 pixels in the vertical direction, for a total of 8 pixels, and is thus determined. Data of a pixel at a predetermined position is cut out from each of the eight pixels and generated as dot formation data.

  In this way, the dot formation data generation unit 184 generates dot formation data in order from the data corresponding to the head drive data to be transmitted to the head 21 first. The dot formation data generation unit 184 generates data corresponding to other remaining pixels on the left side in the drawing at another timing.

(4) Other cases As described above, in the cases (1) to (3) described above, as described with reference to FIGS. 38 to 40, the multi-value gradation value data is regularly obtained every other stage. It was. This is because the nozzle spacing (nozzle pitch, “k · D” in FIG. 7A) of the nozzles # 1 to # 180 of the nozzle rows 211C, 211M, 211Y, and 211K is set to 120 dpi (1/120 inch). Is related. When the nozzle interval of each nozzle # 1 to # 180 of each nozzle row 211C, 211M, 211Y, 211K is set to other than 120 dpi, or when the position of the pixel to be extracted as dot formation data is other position, various other Depending on factors, it may be difficult to regularly acquire multi-value gradation value data in this way.

  FIG. 41 illustrates an example where multi-value gradation value data cannot be regularly obtained. Here, a case where the dot formation data generation unit 184 generates dot formation data in the 4 × 4 mode will be described as an example. The resolution of the original image data, that is, the CMYK image data used to generate the multi-value gradation value data is 360 dpi (horizontal) × 360 dpi (vertical), and the resolution is 1440 dpi (horizontal) × 1440 dpi (vertical). Is printed. When the nozzle interval (nozzle pitch, “k · D” in FIG. 7A) of the nozzles # 1 to # 180 of each nozzle row 211C, 211M, 211Y, 211K is 240 dpi (1/240 inch), the head drive data Corresponding dot formation data is generated as follows.

  As shown on the left side of the figure, the dot formation data has a relationship in which the nozzle interval (nozzle pitch) is 240 dpi (1/240 inch). 240 inches). Here, the dot formation data generation unit 184 has the fourth line from the top, that is, the data corresponding to the first and fifth pixels (pixels indicated by gray in the figure) from the left of “3Line”, and from the top. Data corresponding to the 10th line, that is, here, the first and fifth pixels (pixels indicated by gray in the figure) from the left of “9Line”, and the 16th line from the top, that is, 1 from the left of “15Line” in this case Assume that data corresponding to the fifth and fifth pixels (pixels indicated by gray in the drawing) is generated. The intervals between the two pixels of “3 Line”, the two pixels of “9 Line”, and the two pixels of “15 Line” are 240 dpi (1/240 inch), respectively.

  As shown in the center of the figure, the image of the block of 4 pixels by 4 pixels corresponding to these pixels is divided into two blocks arranged in the first row from the top and two blocks arranged in the third row from the top. The block and two blocks arranged in the fourth row from the top. In addition, as shown on the right side of the figure, the multi-value gradation value data corresponding to these blocks is the data in the first row from the top, that is, the data corresponding to “Address 1” (data shown in gray in the figure). The third row from the top, that is, data corresponding to “Address 3” (data shown in gray in the figure), and the fourth row from the top, that is, data corresponding to “Address 4” (in the drawing, gray) Data).

  Here, the multi-value gradation value data corresponding to two pixels of “3 Line” and the multi-value gradation value data corresponding to two pixels of “9 Line” are arranged with one stage interposed therebetween. On the other hand, multi-value gradation value data corresponding to two pixels of “8 Line” and multi-value gradation value data corresponding to two pixels of “15 Line” are arranged adjacent to each other. . Therefore, since the multi-value gradation value data to be acquired by the dot formation data generation unit 184 is not arranged at equal intervals along the vertical direction, the dot formation data generation unit 184 has the multi-value gradation value. Value data cannot be obtained regularly.

(5) Method for Acquiring Multilevel Tone Value Data etc. Therefore, in this embodiment, the position of the multilevel tone value data to be acquired is acquired by the following calculation method.

  FIG. 42 is a diagram for explaining an example of a method for acquiring multi-value gradation value data according to the present embodiment. Here, for one multi-value gradation value data, when dot formation data extending over 4 raster lines is generated, that is, it corresponds to “2 × 4 mode” or “4 × 4 mode”. A case will be described as an example. The raster lines on the dot formation data side are “0 raster” to “15 raster”, and the raster lines on the multi-value gradation value data side are “0 raster” to “3 raster”. It is assumed that generation is started from pixel data corresponding to “3 raster” in the dot formation data. The raster lines on the dot formation data side are generated at predetermined intervals, here, every “3 raster”. The raster line on the multi-value gradation value data side corresponding to “3 raster” is “0 raster”.

  Here, the position of “3 raster” on the dot formation data side is expressed as “0011” in binary. From this “0011”, a raster line for which data is to be generated next is obtained as dot formation data. Here, “0011” is divided by “4”, that is, “0100”. Then, the upper 2 bits of data are acquired by the binary system, and the division value “01” is acquired. Also, the lower 2 bits of data are acquired, and the remainder “11” is acquired. The remainder of “11” is added with three raster lines, that is, “0011”, thereby obtaining a value of “0110”. Further, this “0110” is divided by “4”, that is, “0100” to obtain a divided value “01” (upper 2 bits). This division value “01” is the raster line shift amount (referred to herein as “offset”) on the multi-value gradation value data side. That is, here, since the raster line of the first multi-value gradation value data is “0 raster”, it is shifted from this “0 raster” by one, and “1 raster” is the raster on the dot formation data side to be generated next. It becomes a raster line of multi-value gradation value data corresponding to the line.

  Further, a raster line from which data is to be generated next is obtained as dot formation data. Here, the remainder obtained by the previous division, that is, the lower 2 bits of data “10” is obtained by the binary method. That is, 3 remainders, that is, “0011” is added to the remainder “10” to obtain “0101”. This “0101” is divided by “4”, that is, “0100” in the same manner as described above. Then, the division value “01” (upper 2 bits) and the remainder “01” (lower 2 bits) are acquired. Since the division value “01” is the raster line shift amount (offset) on the multi-value gradation value data side, “2 raster” is shifted by one from “1 raster” and “2 raster” is to be generated next on the dot formation data side. This is a raster line of multi-value gradation value data corresponding to the raster line.

  On the other hand, when obtaining a raster line for which data is to be generated next as dot formation data, “0011” is added to the remainder “01” obtained by the previous division, and the obtained “ “0100” is divided by “0100” to obtain a division value “01” (upper 2 bits) and a remainder “00” (lower 2 bits). Then, the division value “01” becomes a raster line shift amount (offset) on the multi-value gradation value data side, and “3 raster” corresponds to the raster line on the dot formation data side to be generated next. It becomes a raster line of tone value data.

  Further, when obtaining a raster line for generating data as dot formation data next time, “0011” is added to the remainder “00” obtained by the previous division, and “0011” obtained thereby. Is divided by “0100” to obtain a division value “00” (upper 2 bits) and a remainder “11” (lower 2 bits). Here, the division value “00” is a raster line shift amount (offset) on the multi-value gradation value data side. That is, here, since the division value is “00”, the raster line shift amount (offset) on the multi-value gradation value data side is “0”. That is, the raster line of the multi-value gradation value data corresponding to the raster line on the dot formation data side to be generated next becomes “3 raster” again.

  By sequentially performing such calculation, the position of the raster line of the multi-value gradation value data corresponding to the raster line on the dot formation data side to be generated next can be easily derived. If the number of raster lines of dot formation data generated for one multi-value gradation value data and the raster line interval (corresponding to the nozzle interval) on the dot formation data side are found, Regardless of the pattern, the position of the raster line of the multi-value gradation value data corresponding to the raster line on the dot formation data side to be generated next can be easily derived.

  In this embodiment, these calculations are performed by the controller 414 provided in the dot formation data generation unit. The controller 414 instructs the generation circuit 400 on the order of the multi-value gradation value data to be acquired from the multi-value gradation value data buffer 188 on the SDRAM 102 based on the result obtained by such calculation.

  FIG. 43 is for explaining another example of the acquisition method of multi-value gradation value data of this embodiment. Here, for one multi-value gradation value data, data for dot formation extending over two raster lines is generated, that is, it corresponds to “1 × 2 mode” or “2 × 2 mode”. A case will be described as an example. The raster lines on the dot formation data side are “0 raster” to “15 raster”, and the raster lines on the multi-value gradation value data side are “0 raster” to “7 raster”. It is assumed that generation is started from pixel data corresponding to “5 raster” in the dot formation data. The raster lines on the dot formation data side are generated at predetermined intervals, here, every “3 raster”. The raster line on the multi-value gradation value data side corresponding to “5 raster” is “2 raster”.

  Here, the position of “5 raster” on the dot formation data side is represented by “0101” in the binary system. This “0101” is divided by “2”, that is, “10”. Then, the division value “010” (upper 3 bits) and the remainder “1” (lower 1 bit) are acquired. Three raster lines, that is, “0011” is added to the remainder “1”. As a result, the value “0100” is acquired. Further, this “0100” is divided by “2”, that is, “10” to obtain a divided value “010” (upper 3 bits) and a remainder “0”. Here, the division value “010” is the raster line shift amount on the multi-value gradation value data side (referred to herein as “offset”). That is, here, since the raster line of the first multi-value gradation value data is “2 raster”, “4 raster” at a position shifted by two from this “2 raster” is the dot formation data side to be generated next. This is a raster line of multi-value gradation value data corresponding to the raster line.

  Further, a raster line from which data is to be generated next is obtained as dot formation data. Here, the remainder is obtained from the remainder “0” obtained by the previous division. That is, 3 remainders, that is, “0011” is added to the remainder “0” to obtain “0011”. This “0011” is divided by “2”, that is, “10” in the same manner as described above. Then, the division value “001” (upper 3 bits) and the remainder “1” (lower 1 bit) are acquired. Since the division value “001” is the shift amount (offset) of the raster line on the multi-value gradation value data side, “5 raster” is shifted by one from “4 raster”, and “5 raster” is to be generated next on the dot formation data side. This is a raster line of multi-value gradation value data corresponding to the raster line.

  Further, when obtaining a raster line for generating data as dot formation data next time, “0011” is added to the remainder “1” obtained by the previous division to obtain “0100”. Then, the obtained “0100” is divided by “2”, that is, “10”, and a divided value “010” (upper 3 bits) and a remainder “0” (lower 1 bit) are obtained. Since the division value “010” is the raster line shift amount (offset) on the multi-value gradation value data side, “7 raster” at a position shifted by two from “5 raster” is the dot formation to be generated next. This is a raster line of multi-value gradation value data corresponding to the raster line on the data side.

  Even in such a case, the position of the raster line of the multi-value gradation value data corresponding to the raster line on the dot formation data side to be generated next can be easily derived by sequentially performing the above-described calculation.

  Again, these calculations are performed by the controller 414. The controller 414 instructs the generation circuit 400 on the order of the multi-value gradation value data to be acquired from the multi-value gradation value data buffer 188 on the SDRAM 102 based on the result obtained by such calculation.

<About table data>
As for the above-described method of acquiring multi-value gradation value data, a part of data is read from the dot number data conversion table 410 and the order value matrix 412 stored in the SDRAM 102 on the ASIC 95 side to generate dot formation data. The present invention can also be applied to the case where data is stored in the first buffer 402 or the second buffer 404 (see FIG. 37) of the unit 184. That is, here, in the first buffer 402 and the second buffer 404, a part of the data of the dot number data conversion table 410 and a part of the order value matrix 412 necessary for generating one raster line, respectively. And are stored. From this, by reading a part of the data from the dot number data conversion table 410 and the order value matrix 412 stored in the SDRAM 102 on the ASIC 95 side by the same method as in the case of multi-value gradation value data, The dot formation data generation process can be performed smoothly.

  In this case as well, the order of reading from the SDRAM 102 the partial data of the dot number data conversion table 410 stored in the first buffer 402 and the second buffer 404 and the partial data of the order value matrix 412 is as follows. Calculation is performed by the controller 414.

<Image of reading from SDRAM>
44 shows the multi-value gradation value data (multi-value gradation value data buffer 188) from the SDRAM 102 on the ASIC 95 side, some data in the dot number data conversion table 410, and some data in the order value matrix 412. Is an outline of the processing in the case of sequentially reading out. When reading out multi-value gradation value data (multi-value gradation value data buffer 188), some data in the dot number data conversion table 410, and some data in the order value matrix 412 from the SDRAM 102, As shown in the figure, a read start address is designated from each of the areas storing these multi-value gradation value data (multi-value gradation value data buffer 188), dot number data conversion table 410, and sequence value matrix 412. Thus, by the calculation method described above, that is, the calculation method described with reference to FIGS. 42 and 43, the address to be read next is sequentially specified, and necessary data is read from the SDRAM 102 one after another. As a result, it is possible to automate the reading of multi-value gradation value data (multi-value gradation value data buffer 188) and various tables 410 and 412 from the SDRAM 102. Accordingly, the processing efficiency can be improved.

=== Outline of Dither Method ===
The above-described multi-value processing and dot formation data generation processing are executed based on a so-called dither method. In the multivalue processing and dot formation data generation processing described above, the concept of determining the classification number and the setting method of the multivalue table, dot number data conversion table, sequence value matrix, etc. are all based on this dither method. Yes. Here, the outline of the dither method will be briefly described.

  The dither method is a typical method used for converting image data into data representing the presence / absence of dot formation for each pixel. In this method, a threshold value is set in a matrix called a dither matrix, and the gradation value of each pixel of the image data is compared with the threshold value set in the dither matrix for each pixel. It is determined that a dot is formed for a large pixel, and a dot is not formed for a pixel that is not so. Such a determination is made for all the pixels in the image data. Thereby, the image data can be converted into data representing the presence or absence of dot formation for each pixel.

  FIG. 45 is an explanatory diagram illustrating a part of the dither matrix in an enlarged manner. In the illustrated matrix, threshold values randomly selected from the range of gradation values “1” to “255” are randomly stored in a total of 8192 pixels, 128 pixels in the horizontal direction and 64 pixels in the vertical direction. ing. Here, the threshold gradation value is selected from the range of “1” to “255”. In this embodiment, the pixel of the image data takes the gradation values “0” to “255”. This is because, in addition to the obtained 1-byte data, when the gradation value of the pixel of the image data is equal to the threshold value, it is determined that a dot is formed in that pixel.

  That is, when the dot is formed only in the pixel whose gradation value of the image data is larger than the threshold value (that is, the dot is not formed in the pixel whose gradation value is equal to the threshold value), the image data is A dot is never formed in a pixel having a threshold value equal to the maximum gradation value that can be taken. In order to avoid such a situation, the range that can be taken by the threshold is a range obtained by removing the maximum gradation value from the range that can be taken by the pixel. On the other hand, when dots are formed even in pixels where the gradation value of the image data is equal to the threshold value, dots are always formed in the pixels having the same threshold value as the minimum gradation value that the image data can take. Will end up. In order to avoid such a situation, the range that can be taken by the threshold is a range obtained by excluding the minimum gradation value from the range that can be taken by the image data. In this embodiment, the gradation values that can be taken by the image data are “0” to “255”, and dots are formed in pixels that have the same threshold value as the image data. ”To“ 255 ”. Note that the size of the dither matrix is not limited to the size illustrated in FIG. 45, and may be various sizes including a matrix having the same number of vertical and horizontal pixels.

  FIG. 46 is an explanatory diagram conceptually showing a state in which the presence or absence of dot formation for each pixel is determined with reference to the dither matrix. When determining the presence or absence of dot formation, first, the pixel to be determined is selected, and the gradation value of the image data for this pixel is compared with the threshold value stored at the corresponding position in the dither matrix. . The thin broken arrow shown in FIG. 46 schematically represents that the gradation value of the image data and the threshold value stored in the dither matrix are compared for each pixel. For example, for the pixel in the upper left corner of the image data, the gradation value of the image data is “97” and the threshold value of the dither matrix is “1”, so it is determined that a dot is formed on this pixel. The arrow indicated by a solid line in FIG. 46 schematically represents a state in which it is determined that a dot is to be formed in this pixel and the determination result is written in the memory. On the other hand, for the pixel on the right side of this pixel, the gradation value of the image data is “97”, the threshold value of the dither matrix is “177”, and the threshold value is larger, so no dot is formed for this pixel. Judge. In the dither method, by referring to the dither matrix and determining whether or not to form dots for each pixel, the image data is converted into data representing the presence or absence of dot formation for each pixel.

=== Concept for setting classification number ===
<Classification number>
The classification number is set based on the dither matrix shown in FIG. That is, a total of 8192 pixels are formed in the dither matrix, 128 pixels in the horizontal direction and 64 pixels in the vertical direction. These 8192 pixels are divided into 4 units in the horizontal direction and 2 pixels in the vertical direction as one unit block, and a serial number set individually for each of the divided unit blocks is “classification number”. It has become.

  FIG. 47 is an explanatory diagram showing a concept for setting a classification number. FIG. 47A conceptually shows a state in which a total of 8 pixels of 4 pixels in the horizontal direction and 2 pixels in the vertical direction are divided as one unit block at the upper left corner of the image. FIG. 47B illustrates how the dither matrix pixels are divided in this way and a “classification number” is set for each unit block.

  In the dither matrix, 4 pixels in the horizontal direction and 2 pixels in the vertical direction are divided into one unit block, so that 32 unit blocks are formed in the horizontal direction and the vertical direction, for a total of 1024 unit blocks. Serial numbers are individually set for these 1024 unit blocks. As a result, classification numbers “1” to “1024” are assigned to the respective unit blocks of the dither matrix.

  FIG. 47C illustrates an example in which a dither matrix is applied to image data. When the dither matrix is applied to the image data in this way, at least the classification number “1” is set to the pixel at the upper left corner of the image data. Note that the method of setting the classification number for each pixel of the image data differs according to the resolution (output resolution) when printing the image on the medium S, as described above with reference to FIGS. 13A to 13E. That is, “1 × 1 mode”, “2 × 1 mode”, “1 × 2 mode”, “2 × 2 mode”, “4 × 2 mode”, “2 × 4 mode” and “4 × 4 mode” The method of setting the classification number for each pixel differs depending on each mode.

<Reasons for different classification number settings>
Here, the reason why the method of setting the classification number for each pixel of the CMYK image data differs depending on the resolution (output resolution) when the image is printed on the medium S will be described. That is, the classification number is assigned to each unit block on the dither matrix with 4 pixels in the horizontal direction and 2 pixels in the vertical direction, and a total of 8 pixels as one unit. For this reason, one unit block corresponding to one classification number is applied to 8 pixels. Since the number of pixels on the dot formation data generated from one pixel on the CMYK image data differs depending on the resolution (output resolution) when the image is printed on the medium S, different methods are used for each output resolution. It is necessary to set the classification number at.

In the case of the “1 × 1 mode”, only data for one pixel is generated as dot formation data from one pixel in the CMYK image data. For this reason, the classification number of “1 × 1 mode” is set to the same classification number with a total of eight pixels as one unit, as shown in FIG. 13A, four in the horizontal direction and two in the vertical direction. Will be.
In the “2 × 1 mode”, data for only two pixels arranged in the horizontal direction as dot formation data is generated from one pixel in the CMYK image data. For this reason, the classification number of “2 × 1 mode” is set to the same classification number with a total of four pixels as one unit, as shown in FIG. 13B, two in the horizontal direction and two in the vertical direction. Will be.
In the “1 × 2 mode”, data for only two pixels arranged in the vertical direction as dot formation data is generated from one pixel in the CMYK image data. For this reason, the classification number of “1 × 2 mode” is set to the same classification number with a total of four pixels as one unit, four in the horizontal direction and one in the vertical direction as described in FIG. 13C. Will be.
In the case of the “2 × 2 mode”, only data for a total of four pixels are arranged as two dot formation data in the horizontal direction and two in the vertical direction from one pixel in the CMYK image data. Not generated. Therefore, the classification number of “2 × 2 mode” is set to the same classification number with two pixels arranged in the horizontal direction as one unit, as described in FIG. 13D.
In the case of the “4 × 2 mode”, data of a total of eight pixels arranged in a horizontal direction and two in a vertical direction as dot formation data from one pixel in the CMYK image data. Generated. Therefore, the classification number of “4 × 2 mode” is set differently for each pixel, as will be described with reference to FIG. 13E.

<Identification method of classification number>
FIG. 48 illustrates an example of a method for identifying a classification number. Here, a method for specifying the classification number in the “1 × 1 mode” is described. FIG. 48A shows the position of the pixel of interest on the CMYK image data. The position of the pixel of interest is indicated by a black circle “●”. Assume that the coordinates of the pixel of interest are (X, Y). Since a total of 8 pixels of 4 pixels in the horizontal direction and 2 pixels in the vertical direction are divided as one unit block, the following relational expressions (1) and (2) are established for X and Y.
X = 4n + α (1)
Y = 2m + β (2)
Here, n and m are integers of 0 or more. Moreover, (alpha) is an integer of 0-3. Β is 1 or 0. n represents the number of unit blocks arranged on the left side of the pixel of interest. Further, m represents the number of unit blocks arranged above the target pixel.

For example, as shown in FIG. 48B, the dither matrix is repeatedly applied to each pixel of the CMYK image data while moving little by little in the horizontal direction on the CMYK image data. Here, as shown in FIG. 48C, the unit block of the Mth row and the Nth column in the dither matrix is applied to the target pixel. Since one dither matrix has 32 unit blocks in the horizontal and vertical directions, “M” and “N” can be easily obtained from the following relational expressions (3) and (4). be able to.
N = n-int (n / 32) × 32 + 1 (3)
M = m−int (m / 32) × 32 + 1 (4)
Here, int is an operator representing rounding down to the integer. That is, int (n / 32) represents an integer value obtained by rounding down the numerical value after the decimal point to the calculation result of n / 32. Thus, if the coordinates (X, Y) of the pixel of interest are known, the unit block to which the pixel of interest belongs can be specified from these X and Y. This makes it possible to check which classification number should be set for the pixel of interest.

  Here, the case of “1 × 1 mode” has been described as an example, but in the case of other modes as well, by using individual relational expressions, the coordinates (X, Y) of the pixel of interest The position of the unit block on the dither matrix corresponding to the target pixel can be specified. Thereby, the classification number to be set for the pixel of interest can be derived.

<About other setting methods>
Here, the classification number is set for each unit block as a single unit block with 4 pixels in the horizontal direction and 2 pixels in the vertical direction on the dither matrix. However, in the classification number setting method, Is not limited to such a method. That is, for example, the classification number may be set for each unit block on the dither matrix as a single unit block of 2 pixels horizontally × 2 pixels vertically, or 4 pixels horizontally × 4 pixels vertically. A total of 16 pixels may be set for each unit block as one unit block. In other words, in the above-described embodiment, one unit block has 4 horizontal pixels because of the relationship of determining whether or not dots are formed for a total of 8 pixels, 4 horizontal pixels × 2 vertical pixels, based on one multi-value gradation value data. Although it has a size of 2 pixels × vertical pixels, the size of the unit block to which the classification number is set is not limited to the size of the above-described embodiment.

=== Setting method of multi-level table ===
Next, a setting method of the multi-value table shown in FIG. 12A will be described. As described above, in the multi-value conversion table, multi-value gradation value data is set in association with each pixel gradation value for each pixel classification number. By performing multi-value conversion while referring to the multi-value conversion table, the gradation value of the pixel can be converted into multi-value in a unique mode corresponding to the classification number as shown in FIG. 12B.

  The multi-value conversion table of this embodiment is set based on a technique developed from the above-described dither method so that the presence / absence of dot formation can be determined for each pixel for a plurality of types of dots having different sizes. . Before explaining the setting method of the multi-value table, the basic technical contents necessary for understanding the setting method will be briefly explained.

<Density data>
FIG. 49 is a flowchart showing the flow of halftone processing in which the dither method is developed so that the presence / absence of formation of large dots, medium dots, and small dots can be determined for each pixel. When the halftone process is started, first, a pixel for which it is determined whether or not to form a dot is selected, and a gradation value of the pixel is acquired (step S400). Next, the acquired image data is converted into density data for large, medium, and small dots. Here, the density data is data representing the density at which dots are formed. The density data indicates that dots are formed at a higher density as the gradation value increases. For example, the gradation value “255” of the density data indicates that the dot formation density is 100%, that is, dots are formed in all pixels, and the gradation value “0” of the density data indicates that the dot is formed. This indicates that the formation density is 0%, that is, no dot is formed in any pixel. Such conversion into density data can be performed by referring to a numerical table called a dot density conversion table.

  FIG. 50 is an explanatory diagram conceptually showing a dot density conversion table that is referred to when converting the gradation value of each pixel into density data for large, medium, and small dots. As shown in the figure, the dot density conversion table sets density data for small dots, medium dots, and large dots with respect to the gradation value of the pixel. In the region where the gradation value is near “0”, the gradation value is set to “0” for both the density data of medium dots and large dots. The density data of small dots increases as the gradation value increases, but when the gradation value reaches a certain value, it starts to decrease and the density data of medium dots starts to increase instead. . When the gradation value further increases and reaches a certain value, the density data of the small dots becomes “0”, the density data of the medium dots starts to decrease, and instead the density data of the large dots gradually increases. To go. In step S402 in FIG. 49, processing for converting the gradation value of the pixel into density data for large dots, density data for medium dots, and density data for small dots is performed while referring to the dot density conversion table.

<Judgment of large dot formation>
When the density data of the large, medium, and small dots is obtained for the pixel to be processed, it is first determined whether or not large dots are formed (step S404 in FIG. 49). Such a determination is made by comparing the density data of large dots with the threshold value of the dither matrix set at the corresponding position of the pixel to be processed. If the density data of large dots is larger than the threshold value, it is determined that large dots are to be formed on the pixel to be processed. Conversely, if the density data is smaller, it is determined that no large dots are formed.

  Next, it is determined whether or not it is determined to form a large dot on the pixel to be processed (step S406). If it is determined to form a large dot (step S406: yes), the medium dot and the small dot are determined. This determination is omitted, and it is determined whether or not all pixels have been completed (step S418). If there remains a pixel for which dot formation has not been determined (step S418: no), the process returns to step S400 to select a new pixel, and a series of subsequent processing is performed.

<Determination of medium / small dot formation>
On the other hand, if it is not determined that a large dot is to be formed on the pixel to be processed (step S406: no), the medium dot density data is added to the large dot density data in order to determine whether or not the medium dot is formed. Then, intermediate data for medium dots is calculated (step S408). The intermediate data for medium dots thus obtained is compared with the threshold value of the dither matrix. If the intermediate data for medium dots is larger than the threshold, it is determined that a medium dot is formed. Conversely, if the threshold of the dither matrix is larger than the intermediate data, no medium dot is formed. Judgment is made (step S410).

  Next, it is determined whether or not it is determined to form a medium dot on the pixel to be processed (step S412). If it is determined that a medium dot is to be formed (step S412: yes), the determination regarding the small dot is performed. It is omitted and it is determined whether or not all pixels are finished (step S418).

  If it is not determined that a medium dot is to be formed on the pixel to be processed (step S412: no), the density data of the small dot is added to the intermediate data for the medium dot in order to determine whether or not to form a small dot. Intermediate data for small dots is calculated (step S414). Then, the obtained intermediate data for small dots is compared with the threshold value of the dither matrix. If the intermediate data for small dots is larger than the threshold value, it is determined that a small dot is formed. Conversely, if the dither matrix threshold value is larger than the intermediate data, no dot is formed. Is determined (step S416).

  That is, for a pixel having a larger threshold set in the dither matrix than the large dot density data (a pixel in which no large dot is formed), it is obtained by adding the medium dot density data to the large dot density data. The intermediate data is compared with the threshold value, and if the intermediate data becomes larger, it is determined that a medium dot is formed. On the other hand, for pixels whose threshold is still larger than that of the intermediate data, new intermediate data is calculated by adding density data of small dots to the intermediate data. Then, the intermediate data is compared with the threshold value, and if the new intermediate data is larger, it is determined that a small dot is to be formed, and it is determined that no dot is formed for a pixel having a still larger threshold value. is there.

  By performing the processing as described above, it is possible to determine whether a large dot, a medium dot, or a small dot is to be formed for a pixel to be processed, or whether any dot is not to be formed. Therefore, it is determined whether or not the processing has been completed for all the pixels (step S418). If there are remaining undetermined pixels (step S418: no), the process returns to step S400 to select a new pixel, A series of subsequent processing is performed. In this way, it is determined whether large, medium or small dots are to be formed one by one for the pixel selected as the processing target. If it is determined that the processing has been completed for all pixels (step S418: yes), the halftone processing shown in FIG. 49 is terminated.

  The method for determining the presence / absence of formation for each of the large, medium, and small dots using the dither matrix has been described above. In the following, based on the above description, a setting method of the multi-level table shown in FIG. 12A will be described.

<Conceptual diagram>
As described above, in the multi-value gradation value data generation process and the dot formation data generation process, the presence or absence of dot formation is determined for eight pixels from the gradation value of one pixel of the CMYK image data. Here, the gradation value of one pixel of the CMYK image data is considered to represent the gradation value of eight pixels, and is applied to the above-described halftone processing.

  FIG. 51 illustrates an outline when halftone processing is executed on the assumption that the gradation value of one pixel of CMYK image data represents the gradation value of eight pixels. In the figure, eight pixels of interest for performing halftone processing are shown surrounded by thick solid lines. The gradation values of the eight pixels all have the same value, here the gradation value “97”. In order to determine whether large, medium, or small dots are formed, the gradation value of each pixel is converted into density data for each dot. Conversion to density data is performed by referring to the dot density conversion table shown in FIG. Here, since it is assumed that all the pixels in the eight pixels have the same gradation value, the density data for all the dots and the density data all have the same value for the pixel. In the illustrated example, the gradation value of the density data for large dots is “2”, the gradation value of the density data for medium dots is “95”, and the gradation value of the density data for small dots is “30”. Represents.

  Next, as described with reference to FIG. 49, by comparing the density data of large dots, the intermediate data for medium dots, or the intermediate data for small dots with the threshold values set in the dither matrix, Whether or not dots are formed is determined for each pixel. Here, as the threshold value of the dither matrix used for comparison, a threshold value set in a location corresponding to the eight pixels of interest from the dither matrix is used. For example, in the example shown in FIG. 51, since eight pixels are in the upper left corner of the image, the threshold values set for the eight pixels (one unit block) in the upper left corner of the dither matrix are also set. use.

  Then, among the eight threshold values set for the eight pixels, it is determined that a large dot is formed for a pixel for which a threshold value smaller than the large dot density data is set. Here, since the density data of the large dots is the gradation value “2”, the pixels where the large dots are formed are only the pixels for which the threshold value “1” is set. In FIG. 51, the pixels for which large dots are determined to be formed are displayed with fine diagonal lines. Pixels that are larger than the large dot density data “2” and have a smaller threshold than the medium dot intermediate data “97” obtained by adding the large dot density data and the medium dot density data. Is determined to form a medium dot. There are only two such pixels, a pixel for which the threshold “42” is set and a pixel for which the threshold “58” is set. In FIG. 51, pixels that are determined to have medium dots formed are displayed with a slightly rough diagonal line. Finally, it is larger than intermediate data “97” for medium dots, and smaller than intermediate data “127” for small dots obtained by adding density data for small dots to intermediate data for medium dots. It is determined that a small dot is formed in a pixel for which a threshold is set. Such pixels are only those for which the threshold value “109” is set. In FIG. 51, the pixels for which small dots are determined to be formed are displayed with rough diagonal lines. In this way, when the gradation value of the pixel of interest is “97” as a result of determining whether or not large dots, medium dots, and small dots are formed, one large dot, two medium dots, One small dot is formed.

  If the gradation values of the pixels are greatly different, the numbers of large dots, medium dots, and small dots formed in the eight pixels are also different. Further, if the gradation value of the pixel is changed from “0” to “255”, the number of large dots, medium dots, and small dots should be changed in several steps. Furthermore, if the classification number set for the pixel is different, the threshold value of the dither matrix is also different, so the way of changing the number of dots should be different. The multi-value conversion table shown in FIG. 12A examines, for each classification number, the behavior in which the number of various dots changes stepwise when the gradation value of a pixel is changed from “0” to “255”. Is set by.

<Generation method of multi-value table>
FIG. 52 is a flowchart showing a flow of processing for actually setting a multi-level table. Hereinafter, it demonstrates according to a flowchart. When the multi-value conversion table setting process is started, first, one classification number is selected (step S500). For example, it is assumed here that the classification number “1” is selected.
Next, the threshold corresponding to the selected classification number is read out from the dither matrix (step S502). For example, since the classification number “1” is selected here, eight threshold values set at the block position indicated by “1” in FIG. 47B are read out from the dither matrix illustrated in FIG. .
Then, the multi-value gradation value data RV and the gradation value BD of the pixel are set to “0” (step S504), and the formation numbers of large dots, medium dots, and small dots are all set to 0 ( Step S506).

  Subsequently, by referring to the dot density conversion table shown in FIG. 50, after converting the gradation value of the pixel into density data for large dots, medium dots, and small dots (step S508), these density data and the previous data are converted. Based on the threshold value read in step S510, the number of formed dots for large, medium, and small dots is determined (step S510). That is, as described with reference to FIG. 49 or 51, the number of threshold values smaller than the large dot density data is obtained, and the obtained number is used as the large dot formation number. Further, the number of threshold values larger than the density data for large dots and smaller than the intermediate data for medium dots is obtained, and this is set as the number of medium dots formed. Further, the number of thresholds larger than the intermediate data for medium dots and smaller than the intermediate data for small dots is obtained, and this is used as the number of small dots formed.

  It is determined whether or not the number of dots formed in this way has been changed from the previously set number of dots (step S512). If it is determined that the number of formations has been changed (step S512: yes), the multi-value gradation value data RV is increased by “1” (step S514), and the obtained multi-value gradation value data RV is changed. It is stored in association with the gradation value BD of the pixel (step S516). On the other hand, if it is determined that the number of formations has not been changed (step S512: no), the multi-value gradation value data RV is not increased and stored as it is in association with the pixel gradation value BD. (Step S516).

  As described above, when the multi-value gradation value data for the gradation value of a certain pixel is stored, it is determined whether or not the gradation value BD of the pixel has reached the gradation value 255 (step S518). If the gradation value 255 has not been reached (step S518: no), the gradation value BD of the pixel is increased by “1” (step S520), and the process returns to step S508 to again convert the gradation value BD of the pixel into density data. After the conversion, the multi-value gradation value data RV is stored in association with the gradation value BD of the new pixel by performing the following series of processes (step S516). Such an operation is repeated until the gradation value BD of the pixel reaches the gradation value 255. When the gradation value BD of the pixel reaches the gradation value 255 (step S516: yes), all multi-value gradation value data is set for the selected classification number.

  Therefore, it is determined whether or not the above processing has been performed for all the classification numbers (step S522). If there is an unprocessed classification number (step S522: no), the process returns to step S500 and again. The above-described processing is performed. Such processing is repeated, and if it is determined that all multi-value gradation value data have been set for all classification numbers (step S522: yes), the multi-value conversion table setting processing shown in FIG. 52 is terminated.

  As is clear from the above description, the multi-value gradation value data is stored at the position corresponding to the classification number in the dither matrix and the density data of the large, medium, and small dots obtained by converting the gradation value of the pixel. It is determined by the threshold value. Here, since the dot density conversion table shown in FIG. 50 refers to the same table even if the classification numbers are different, the density data of each dot corresponding to the gradation value of the pixel is the same density data regardless of the classification number. can get. However, the set of threshold values read from the dither matrix is different for each classification number. This is because the dither matrix allows the thresholds to be dispersed as much as possible so that dots do not occur in a fixed pattern on the image, or do not deteriorate image quality due to clumping at close positions. Only randomly set. For this reason, when a plurality of threshold values corresponding to the classification numbers are viewed as a set, it is considered that the possibility of the same combination is extremely low. For this reason, in the multi-value conversion table referred to in the multi-value gradation value data generation process of the present embodiment, the correspondence between the pixel gradation value and the multi-value gradation value data differs for each classification number. In addition, the number of times the multi-value gradation value data changes (the number of multi-value levels shown in FIG. 12B) also differs depending on the classification number.

=== How to set the dot count data conversion table ===
Next, a method for setting the dot number data conversion table shown in FIG. 16 will be described. This dot number data conversion table represents the number of dots formed in eight pixels corresponding to the classification number by combining the multi-value gradation value data with the classification number during the dot formation presence / absence determination process shown in FIG. It is a table referred in order to convert into dot number data.

  As is clear from the setting method of the multi-value conversion table described in FIG. 52, the multi-value gradation value data set in the multi-value conversion table is large, medium, and small formed in eight pixels corresponding to the classification numbers. Is determined based on the number of dots. However, the multi-value gradation value data does not immediately correspond to the combination of the number of dots formed in the eight pixels corresponding to the classification number, but by combining the multi-value gradation value data and the classification number. For the first time, it can be associated with a specific dot number combination. This is because multi-value gradation value data indicates whether or not the number of large, medium, and small dots formed changes when the gradation value of a pixel is increased from gradation value “0” to gradation value “255”. This is because the information indicating how the combinations of the numbers of dots have changed is set in a state where the number of dots is extracted.

  However, if the classification number is known, the number of changes corresponding to the eight pixels corresponding to the classification number, that is, a specific number of combinations of various dots from the multi-value gradation value data Can be specified. Therefore, for each classification number, the specific number of various dots from which the multi-value gradation value data is set is obtained, and the code data corresponding to the obtained combination of dot numbers is obtained as the multi-value gradation value data. Are stored in association with each other. The dot number data conversion table shown in FIG. 16 is set by performing such an operation for all classification numbers.

  FIG. 53 is a flowchart showing a specific processing flow for setting the dot number data conversion table. Hereinafter, it demonstrates according to a flowchart. When the dot number data conversion table setting process is started, first, one classification number to be set is selected (step S600), and the multi-value gradation value data RV is set to 0 (step S602).

  Next, the number of large, medium, and small dots corresponding to the multi-value gradation value data RV is acquired (step S604). For example, if the multi-value gradation value data is “N”, it is determined whether the large, medium, and small dots are formed while changing the gradation value of the pixel from “0” to “255” for the classification number. The number of large dots, medium dots, and small dots when the number of dots formed changes to the Nth is acquired.

  The combination of the number of dots acquired in this way is converted into code data (step S606). Conversion from the combination of the number of dots to code data is performed by referring to the correspondence table shown in FIG. Next, after the obtained code data is stored in association with the multi-value gradation value data (step S608), it is determined whether or not the maximum multi-value conversion result for the target classification number has been reached (step S608). Step S610). That is, as described with reference to FIG. 12B, the maximum value of the multi-value gradation value data differs depending on the classification number, and thus reaches the maximum value of the multi-value gradation value data for the target classification number. It is judged whether or not it was done.

  If the maximum value of the multi-value gradation value data has not been reached (step S610: no), the value of the multi-value gradation value data RV is increased by “1” (step S612). Then, the process returns to step S604, and after acquiring the number of dots corresponding to the new multi-value gradation value data RV, a series of subsequent processes are repeated. If it is determined that the maximum value of the multi-value gradation value data of the target classification number has been reached (step S610: yes), all data is set in the dot number data conversion table for that classification number. It will be done.

  Therefore, this time, it is determined whether the same processing has been performed for all the classification numbers (step S614). If a classification number that has not yet been processed remains, the process returns to step S600 to select a new classification number, and the above-described series of processing is performed on this classification number. If it is determined that the processing has been completed for all the classification numbers (step S614: yes), all the data in the dot number data conversion table has been set, so the processing shown in FIG. 53 is terminated.

=== How to set the order value matrix ===
Next, a method for setting the order value matrix described with reference to FIG. 18 will be described. As described above, the order value matrix is a matrix in which the order in which dots are formed is set for each of the eight pixels corresponding to the classification number. In the dot formation data generation process, an order value matrix corresponding to a classification number is read, and pixels for forming large dots, medium dots, and small dots are determined according to the order set in the matrix.

  The order value matrix is also set on the basis of the above-described method, similarly to the above-described multilevel table. That is, when setting a multi-value table, it is assumed that all the pixels in the eight pixels have the same gradation value as described above, while determining the number of large, medium, and small dots formed in the eight pixels. The gradation value of the pixel was changed from “0” to “255”, and the multi-value gradation value data was set by paying attention to the change in the number of dots formed at this time. Also, as shown in FIG. 16, by combining multi-value gradation value data and classification numbers, it was possible to restore up to the number of large, medium, and small dots formed in eight pixels. However, information on which of the eight pixels these various dots are formed is omitted, and cannot be known from the multi-value gradation value data or the classification number. The order value matrix can be considered to store information on pixel positions where various dots are formed in eight pixels. That is, by applying the above-described method, as described with reference to FIGS. 49 to 51, not only the number of various dots formed, but also the pixel positions where dots are formed in eight pixels can be determined. In this embodiment, this technique is divided into two elements, and information on the number of dots formed is mainly multi-value gradation value data (more precisely, a combination of multi-value gradation value data and classification number). The information regarding the pixel position where the dot is formed can be considered to be reflected in the order value matrix. In practice, such an order value matrix can be set relatively easily.

  FIG. 54 is an explanatory diagram specifically showing a method for setting an order value matrix. Hereinafter, description will be given with reference to the drawings. In the dither matrix, as shown in FIG. 54A, 4 horizontal pixels and 2 vertical pixels are divided into one unit block, and a classification number is individually set for each of the divided unit blocks. When setting the order value matrix, each threshold corresponding to eight pixels for each classification number is extracted from the dither matrix.

  FIG. 54B is an explanatory diagram showing a state in which an order value matrix is generated from a block with a classification number “1” as an example. The threshold value of the dither matrix included in the block with the classification number “1” is shown on the left side of FIG. 54B. As described above with reference to FIG. 51, the dots are formed in order from the pixel for which the small threshold is set. Therefore, the pixel in which the first dot is formed in the block with the classification number “1” shown in FIG. 54B can be considered as the pixel for which the threshold value “1” is set. Therefore, “1” is set as the order value for this pixel. Similarly, the pixel in which the second dot is formed can be considered as a pixel in which the threshold value “42” that is the second smallest threshold value is set. Therefore, an order value “2” is set for this pixel. In this way, if the order value “1” to the order value “8” are determined in order from the pixel with the smallest threshold value set in the block of the classification number “1”, it is shown on the right side of FIG. 54B. An order value matrix of classification number “1” can be obtained.

  Similarly, FIG. 54C shows the order value matrix of the classification number “2” by setting the order value “1” to the order value “8” in order from the pixel in which a small threshold is set in the block. Is shown. An order value matrix from classification numbers “1” to “1024” can be obtained by performing the above operation for all the blocks from classification numbers “1” to “1024” shown in FIG. 54A. .

=== Principle capable of appropriately determining dot formation presence / absence from multi-value gradation value data ===
As described above, in the present embodiment, the multi-value gradation value data is determined by referring to the multi-value conversion table described with reference to FIG. 12A. Next, referring to the dot number data conversion table described with reference to FIG. 16 and the order value matrix described with reference to FIG. 18, the multi-value gradation value data is converted into dot number data, and based on the dot number data. Pixel positions for forming various dots in a plurality of pixels are determined. Even when the pixel positions for forming dots are determined in this way, a high-quality image in which dots are appropriately dispersed can be output. In addition, the number of pixels typified by a so-called blue noise mask or green noise mask exceeds 1000, although a relatively small number (8 in this embodiment) of pixels are collectively processed. It is possible to obtain a good dot distribution as realized by using such a large-scale dither matrix. Below, the principle which enables such a thing is demonstrated.

  If the above-described method is used, as described with reference to FIGS. 49 and 50, the image data is converted into large dot density data, medium dot intermediate data, and small dot intermediate data and set in the dither matrix. By comparing with the threshold value, it is possible to determine whether or not each large, medium, and small dot is formed. Furthermore, if the dither matrix to be referred to at this time is a matrix in which dispersibility is considered as represented by a so-called blue noise mask or green noise mask, a high-quality image in which dots are well dispersed can be obtained. Can do.

  In general, image data tends to be assigned an approximate (or the same) gradation value between adjacent pixels. In recent years, the resolution of image data tends to increase more and more due to the demand for higher image quality, but the tendency to assign an approximate or identical gradation value between adjacent pixels becomes more prominent as the resolution of the image data increases. . Therefore, as described above with reference to FIG. 51, a plurality of pixels are grouped, and it is determined whether or not each large, medium, and small dot is formed assuming that all the pixels in the plurality of pixels have the same gradation value. Even in this case, it is rare that a difference in image quality actually occurs.

  Here, in the multi-value gradation value data generation process described above, the gradation value of the pixel is converted into multi-values, and multi-value gradation value data depending on the classification number is generated. The multi-value gradation value data generated in this way is data indicating the number of various dots formed in the eight pixels by combining with the pixel classification number. The eight pixels shown in FIG. 51 are combined with classification numbers to indicate that the number of large dots, medium dots, and small dots formed is one, two, and one, respectively. The key value data is generated.

  In the dot formation data generation process described above, when such multi-value gradation value data is received, the presence / absence of formation for each large, medium, and small dot is determined for each pixel in the eight pixels. FIG. 55 conceptually shows a general flow of processing for receiving multi-value gradation value data and determining whether or not large, medium, and small dots are formed for each of the eight pixels in the dot formation data generation processing described above. It is explanatory drawing put together. As shown in the figure, when multi-value gradation value data is received, after obtaining the classification number of the pixel to which the multi-value gradation value data corresponds, based on the multi-value gradation value data and the classification number, Get the number of large, medium, and small dots. Further, the matrix stored in association with the classification number is read out from the sequence value matrix stored in advance.

  If the description is made assuming the eight pixels shown in FIG. 51, since the eight pixels are in the upper left corner of the image, the classification number is obtained as “1”. It can be seen that one large dot, two medium dots, and one small dot are formed in these eight pixels by combining the multi-value gradation value data and the obtained classification number. In order to determine which of the eight pixels each dot is formed in, the order value matrix with the classification number “1” is referred to. This order value matrix in FIG. 51 is generated from the corresponding portion of the dither matrix used for determining the presence / absence of dot formation, that is, the order used to determine the presence / absence of dot formation for each of the eight pixels. It is a value matrix.

  Based on the number of large, medium, and small dots obtained in this way and the order value matrix, the pixel positions for forming these dots in the eight pixels are determined. Since the specific method for determining the pixel position has already been described with reference to FIG. 19, when the description is omitted here and only the result is shown, a large dot is formed in the pixel having the order value 1. The dots are formed on the pixel with the order value 2 and the pixel 3, and the small dots are formed on the pixel with the order value 4. In FIG. 55, following FIG. 19, pixels that form large dots are finely hatched, pixels that form medium dots are slightly roughed, and pixels that form small dots are coarsely hatched. It is attached. If the dot distribution obtained in this way is compared with the dot distribution obtained by determining the presence or absence of dot formation for each pixel shown in FIG. 51, it is found that the two dot distributions are completely the same. I understand.

  That is, even when only multi-value gradation value data depending on the classification number is received, if the presence or absence of dot formation is determined using the method described above, formation of large, medium, and small dots for each pixel with reference to the dither method It is possible to obtain the same dot distribution as when the presence or absence is determined. For this reason, it is possible to obtain a high-quality image in which dots are well dispersed.

  In addition, the multi-value conversion table referred to for generating the multi-value gradation value data is set based on the dither matrix (see FIG. 53). Similarly, the dot number data conversion table or the order value matrix referred to in the process of determining the dot formation presence / absence from the multi-value gradation value data is also set based on the dither matrix (see FIGS. 53 and 54). Therefore, if a so-called blue noise mask or green noise mask is used as the dither matrix used for setting these tables, it is possible to obtain a high-quality image that can be obtained for the first time by using these masks. Become.

=== Summary ===
As described above, in the present embodiment, the tone value of each pixel of the CMYK image data generated by the color conversion processing unit 180 is converted into multi-value tone value data by the multi-value processing unit 182 and the dot formation data. The generation unit 184 converts the multi-value gradation value data into dot number data, and determines whether or not to form dots individually for a predetermined number of pixels (eight pixels here) based on the dot number data. Then, a predetermined number of pixels are cut out according to the resolution of the output image from the pixels (in this case, eight pixels) for which the presence or absence of the dot formation is determined, and dot formation data is generated according to the resolution of the output image. Therefore, the process of generating the dot formation data can be performed smoothly and efficiently. Thereby, speeding up of image processing and data transfer can be achieved.

  In this embodiment, it is not necessary to perform conversion processing to the resolution (output resolution) when printing on the medium S before performing multi-value processing, and the dot formation data generation unit 184 performs dot formation. Since conversion is performed in accordance with the resolution (output resolution) when printing on the medium S at the data generation stage, it is possible to greatly suppress the generation of the data amount during image processing.

  Further, since the multi-value gradation value data generated here is data of a predetermined number of bits (here, 5 bits) independent of the resolution of the output image, the multi-value gradation value data on the SDRAM 102. Can be made constant regardless of the resolution of the image (output image) printed on the medium S, in order to set the multi-value gradation value data buffer 188 for storing. Thereby, when printing an image on the medium S with high resolution, the size of the multi-value gradation value data buffer 188 secured on the SDRAM 102 can be greatly reduced. In addition, the number of accesses to the SDRAM 102 can be suppressed. For these reasons, it is possible to further increase the speed of image processing and data transfer.

  Moreover, since the multi-value gradation value data generated by the multi-value processing by the multi-value processing unit 182 is data represented by a predetermined number of multi-value levels, even when printing an image, An image to be printed can be printed with sufficiently high image quality.

  Further, the dot formation data generation unit 184 individually determines whether or not dots are formed for each of a predetermined number of pixels (eight pixels in this case) based on the dot number data. A process of generating dot formation data according to the resolution of the output image by cutting out a predetermined number of pixels according to the resolution of the output image from the determined predetermined number of pixels (eight pixels here). It can be done smoothly.

  In addition, by appropriately changing the position of the pixel to be cut out from the eight pixels for which the presence / absence of dot formation has been determined, it is possible to easily perform the process of generating the dot formation data according to the resolution of the output image.

  Further, since the position of the raster line of the multi-value gradation value data corresponding to the raster line on the dot formation data side to be generated next can be easily derived by calculation, the processing can be performed smoothly. Processing speed can be increased. In particular, here, the number of raster lines of dot formation data generated for one multi-value gradation value data and the raster line interval (corresponding to the nozzle interval) on the dot formation data side are found. For example, in any pattern, the position of the raster line of the multi-value gradation value data corresponding to the raster line on the dot formation data side to be generated next can be easily derived.

=== Other Embodiments ===
<Other multi-level tables>
In the above-described embodiment, the multi-value conversion table in which multi-value gradation value data corresponding to each gradation value from “0” to “255” is set is used as the multi-value conversion table. However, since the multi-value gradation value data only increases stepwise as the gradation value of the pixel of the CMYK image data increases, it is only necessary to set the gradation value at which the multi-value gradation value data switches. , Multi-value gradation value data corresponding to the gradation value of each pixel of the CMYK image data can be obtained.

  FIG. 56 illustrates an example of a multi-value conversion table in which only gradation values for switching multi-value gradation value data are set. In this multi-value conversion table, the gradation values of the pixels of the CMYK image data corresponding to the multi-value gradation value data “0” to “31” for each of the classification numbers “1” to “1024”, respectively. A threshold is set. This threshold value indicates the largest gradation value that becomes the multi-value gradation value data when the gradation value is increased from “0” to “255”. As an example, in the classification number “1”, the threshold value “2” is set for the multi-value gradation value data “0”. For the classification number “1”, if the gradation value of the pixel of the CMYK image data is in the range from “0” to “2”, the multi-value gradation value data is “0”. ing. A threshold value “15” is set for the multi-value gradation value data “1”. For the classification number “1”, if the gradation value of the CMYK image data is in the range of “3” to “15”, the multi-value gradation value data is “1”. Similarly, a threshold value “243” is set for the multi-value gradation value data “14”, and a threshold value “255” is set for the multi-value gradation value data “15”. . This indicates that if the gradation value of the pixel of the CMYK image data is in the range from “244” to “255”, the multi-value gradation value data becomes “15”. The classification number “1” indicates that the maximum value of the multi-value gradation value data is “15”.

  In FIG. 56, it is assumed that the threshold values for the classification numbers “1” to “1024” are set in correspondence with the multi-value gradation value data. However, the thresholds for each of the classification numbers “1” to “1024” are not particularly associated with the multi-value gradation value data, and a simple threshold set may be stored for each of the classification numbers “1” to “1024”. . In this case, the multi-value gradation value data can be obtained by counting the number of threshold values smaller than the gradation value of the pixel of the CMYK image data. Here, the case of classification number “1” will be described as an example. For example, assume that the gradation value of the CMYK image data is “20”. In the set of threshold values set for the classification number “1”, there are three threshold values “2”, “15”, and “18” that are smaller than the gradation value “20”. Therefore, the multi-value quantization result value for the gradation value “20” may be obtained as “3”.

  As described above, when such a multi-value conversion table is provided, multi-value gradation value data can be easily generated after obtaining the gradation value and classification number of the pixel of the CMYK image data. In addition, this multi-value conversion table can be stored with a smaller amount of data than the multi-value conversion table shown in FIG. 12A described above. For this reason, here, it is possible to greatly save the memory usage as compared with the case where the multi-value conversion table shown in FIG. 12A described above is provided.

<Other methods for determining the presence or absence of dot formation (1)>
In the above-described embodiment, the dot formation data generation unit 184 converts the multi-value gradation value data into dot number data representing the number of dots to be formed for eight pixels, so that eight pixels (“4 × 4 In the case of “mode”, when determining whether or not to form dots for 16 pixels (the same applies hereinafter), whether or not to form dots for each of the 8 pixels is determined for each dot type (size). did. For example, as described in FIG. 19, first, the presence / absence of dot formation is determined for a large dot, the presence / absence of dot formation is determined for a medium dot, and finally the presence / absence of dot formation is determined for a small dot. The procedure was taken. However, the method for determining the presence / absence of dot formation is not limited to such a method. For example, one pixel may be selected from eight pixels, and it may be determined for each pixel whether a large, medium, or small dot is formed or a dot is not formed.

  FIG. 57 is a flowchart showing the flow of dot formation by the dot formation data generation unit 184 in this case. Here, similarly to the dot formation presence / absence determination process described above, first, multi-value gradation value data to be processed is acquired (step S700). Next, a classification number corresponding to the acquired multi-value gradation value data is acquired (step S702). Then, dot number data is acquired based on the classification number and the multi-value gradation value data (step S704). The dot number data is acquired, for example, using the dot number data conversion table described with reference to FIG.

  Thereafter, in the processing described here, the acquired dot data is temporarily converted into intermediate data having a 16-bit length (step S706). That is, for example, in the dot number data conversion table described with reference to FIG. 16, the dot number data is represented as 8-bit code data in order to reduce the data amount. However, in the processing described here, the presence or absence of dot formation is temporarily converted into intermediate data expressed in a format that can be determined more easily. Here, the data length of the intermediate data is 16 bits. The number of pixels for which the presence / absence of dot formation should be determined is 8, and the presence / absence of dot formation for each pixel can be expressed by 2 bits. Because it is. In other words, the intermediate data is data representing the number of dots using 8 sets of data corresponding to the number of pixels, with 2 bits each as one set. If the number of dots formed in the eight pixels is expressed in such a format, it becomes easy to correspond to the pixels as will be described later, and therefore it is possible to easily determine whether or not dots are formed. In the dot formation presence / absence determination process described here, the correspondence between the dot count data and the intermediate data is stored in advance, and in the process of step S706, the intermediate data is acquired by referring to the correspondence. To do.

  FIG. 58 is an explanatory diagram showing a correspondence table in which dot number data and intermediate data are associated with each other. As described above, the dot number data is associated with combinations of the numbers of dots of various sizes (see FIG. 17). From this, 16-bit data can be obtained by converting the representation format in which 2 bits represent a set of dots and the bit set is converted into a number corresponding to the number of dots. The 16-bit intermediate data is data obtained by converting the expression format of the dot count data in this way.

For example, the dot number data “1” indicates a combination of 0 large dots, 0 medium dots, and 1 small dot. The right side of FIG. 58 shows combinations of dot numbers indicated by the dot number data. If the 2-bit data representing a small dot is “01”, the 16-bit data corresponding to the code data “1” contains only one set of “01”, and the other 7 sets of 2-bit data are “ 00 ”data. The 2-bit data “00” indicates that no dot is formed.
Similarly, the dot number data “163” indicates a combination of seven large dots, one medium dot, and zero small dots. If the 2-bit data representing a large dot is “11” and the 2-bit data representing a medium dot is “10”, the 16-bit data corresponding to the dot count data “163” is the 2-bit data “11”. Seven sets are included, and the data includes one set of 2-bit data “10”.

  These 2-bit data are set right-justified in the order of large dots, medium dots, and small dots. For example, if the combination of the number of dots is one large dot, two medium dots, and three small dots, among the two sets of 2-bit data, the 2-bit data “11” representing the large dot is at the right end. Only one set is set, two sets of 2-bit data “10” representing medium dots are set to the left next to the set, and three sets of 2-bit data “01” representing small dots are set to the left next to the set. In the remaining two sets, 2-bit data “00” indicating that dots are not formed is set. However, these 2-bit data may be set left justified. That is, the order may be set from the left in the order of large dots, medium dots, and small dots.

  In S706 of the dot formation presence / absence determination process described with reference to FIG. 57, a process of converting data representing the number of dots into intermediate data is performed by referring to the correspondence relationship illustrated in FIG. In the above description, the multi-value gradation value data is once converted into the dot number data by referring to the dot number data conversion table described in FIG. 16, and then based on the correspondence described in FIG. Thus, the dot count data is converted into 16-bit intermediate data. However, since the dot number data and the intermediate data are associated with each other on a one-to-one basis, the dot number data conversion table described with reference to FIG. 16 includes 16-bit intermediate data instead of 8-bit dot number data. Is set as dot number data, it is possible to immediately acquire intermediate data as dot number data. In this way, although the data amount of the dot number data conversion table increases, a conversion table from dot number data to intermediate data becomes unnecessary, and intermediate data can be acquired quickly.

  After obtaining the intermediate data as described above, next, an order value matrix is obtained (step S708). After obtaining the order value matrix, one pixel for determining whether or not to form dots is selected from the eight pixels (step S710), and the order value set at the selected pixel position in the order value matrix is selected. Obtain (step S712).

  Next, it is possible to determine the presence / absence of dot formation for the selected pixel by reading the 2-bit data set at the position corresponding to the sequence value from the previously acquired intermediate data. (Step S714).

  FIG. 59 is an explanatory diagram showing a state in which the presence / absence of dot formation is determined by reading the data corresponding to the sequence value from the intermediate data. FIG. 59A illustrates the intermediate data obtained by converting the dot number data. As described above, the intermediate data is 16-bit data, and is composed of 8 sets of 2 bits each. The intermediate data shown in FIG. 59A includes one set of 2-bit data “11” representing a large dot, two sets of 2-bit data “10” representing a medium dot, and 2-bit data “01” representing a small dot. 3 sets and 2 sets of 2-bit data “00” indicating that dots are not formed, and these 2-bit data are set right-justified in the order of large dots, medium dots, and small dots.

  Here, for example, it is assumed that the order value of the pixel for which dot formation is determined is “3”. In this case, if the 2-bit data set in the third set from the right is read from the intermediate data, the type of dot to be formed on the pixel having the order value “3” can be determined. FIG. 59B conceptually shows a state where 2-bit data in the third set from the right end of the intermediate data is read. In the illustrated example, since the read 2-bit data is “10”, it may be determined that a medium dot is formed in this pixel. If the order value is “1”, the 2-bit data (“11”) set at the right end of the intermediate data may be read out and determined to form a large dot.

  As described above, in the dot formation presence / absence determination process, the dot formation presence / absence is determined by an extremely simple operation of reading out the 2-bit data set in the portion corresponding to the sequence value from the intermediate data. Can do. This is due to the following reason. First, in the intermediate data, 2-bit data representing large dots, medium dots, and small dots is set right-justified. On the other hand, as described with reference to FIGS. 49 and 51, in the process of determining the presence / absence of large / medium / small dots using the dither method, the presence / absence of dot formation is determined in the order of large dots, medium dots, and small dots. ing. Therefore, if the 2-bit data set as the intermediate data is read in order from the right end, the same order as that in which the pixel positions for forming various dots are determined by applying the method described above with reference to FIGS. 49 and 51 is used. In order, an array of 2-bit data representing large dots, medium dots, and small dots is obtained.

  In the method described above with reference to FIG. 49 and FIG. 51, dots are formed in order from the pixel in which a small threshold is set in the dither matrix. On the other hand, the order value set in the order value matrix represents the order in which the threshold values set in the dither matrix are small. Therefore, the order value matches the order in which dots were formed when the presence or absence of dot formation was determined using the method described above with reference to FIG.

  From this, if the order value of the target pixel is known, when the method of FIG. 49 or FIG. 51 is applied, the pixel in which the dot is formed among the eight pixels is determined. Further, if the intermediate data is counted from the right end and the 2-bit data of the order value set is read, the determination result of dot formation presence / absence obtained when the method of FIG. 49 or 51 is applied can be known. Can do it.

  Here, the description has been given on the assumption that the location where 2-bit data is read out in the intermediate data is changed according to the sequence value, but the location where data is read out is not changed, but the location where data is read out is fixed. The intermediate data may be shifted by the number of sets corresponding to the order value. Even in this way, it is possible to determine the presence or absence of dot formation. FIG. 59C is an explanatory diagram conceptually showing a state in which the presence / absence of dot formation is determined by shifting the intermediate data. In the example shown, the 2-bit data at the right end of the intermediate data is read out, and the intermediate data is shifted rightward by the number of sets corresponding to the order value of the pixels (specifically, the number of sets less by 1 from the order value). I am letting. As is apparent from a comparison between FIG. 59B and FIG. 59C, in any case, the 2-bit data set at the same location in the intermediate data is eventually read out. Since the process of shifting the data by a predetermined number of bits can be performed at a relatively high speed, if the intermediate data is shifted in this way, the 2-bit data at the location corresponding to the sequence value can be read quickly. The presence or absence of dot formation for the pixel of interest can be quickly determined.

  As described above, when the presence or absence of dot formation for the pixel of interest is determined by reading the 2-bit data set at the position corresponding to the order value from the intermediate data (step S714 in FIG. 57). ), It is determined whether or not dot formation has been determined for all eight pixels (step S716). If there are pixels that have not yet been determined whether or not to form dots among the eight pixels (step S716: no), the process returns to step S710 to select one new pixel. After performing the series of processes described above, it is determined again whether or not dot formation has been determined for all eight pixels (step S716). Such operations are repeated until it is determined whether or not dot formation has been determined for all eight pixels. If it is determined that determination has been made for all pixels (step S716: yes), then all the multi-value gradation value data has been described above. It is determined whether processing has been performed and whether or not dot formation has been determined (step S718). If unprocessed multi-value gradation value data remains (step S718: no), the process returns to step S700 to acquire new multi-value gradation value data, and a series of the multi-value gradation value data is obtained. Process. Such operations are repeated, and when it is determined that the processing for all the multi-value gradation value data is finally finished (step S718: yes), the dot formation presence / absence determination processing is finished.

  As described above, here, it is possible to simply determine the presence or absence of dot formation simply by reading out the 2-bit data set at an appropriate location according to the sequence value from the intermediate data. From this, it is possible to quickly determine whether or not dots are formed in this way, and thus it is possible to print an image more quickly.

  Here, the case where the presence / absence of dot formation is determined for each of the eight pixels has been described, but in the “4 × 4 mode” of the present embodiment, the presence / absence of dot formation is determined for each of the 16 pixels. become. That is, the intermediate data is set based on the dot number data in the “4 × 4 mode” described with reference to FIG. 32 and the combinations of the numbers of dots of various sizes.

<Another method for determining the presence or absence of dot formation (2)>
In the above-described embodiment, by referring to the dot number data conversion table described with reference to FIG. 16, the multi-value gradation value data is once converted into dot number data, and then the order value matrix is referred to as 8 The position of the pixel forming the dot in one pixel (in the case of “4 × 4 mode”, 16 pixels, the same applies hereinafter) was determined. However, in the determination of the presence or absence of dot formation, as described above, without determining the position of the pixel that forms the dot with reference to the order value matrix, immediately based on the acquired multi-value gradation value data, It is also possible to determine pixel positions where various dots are formed. This method will be described in detail below.

  In the above-described embodiment, as described with reference to FIG. 55, after the multi-value gradation value data and the classification number are acquired, eight pixels are formed from the combination of the multi-value gradation value data and the classification number. The number of various dots to be determined was determined. The pixel positions where these dots are formed are determined by referring to the order value matrix corresponding to the classification number. That is, if the multi-value gradation value data and the classification number are determined, the types of dots formed in each of the eight pixels can be determined. Therefore, if the types of dots formed in each pixel in the eight pixels are obtained and stored in the correspondence table for each combination of the multi-value gradation value data and the classification number, the correspondence table is referred to. By simply doing, it should be possible to immediately determine whether or not dots are formed. The dot formation presence / absence determination process described here can quickly determine the presence / absence of dot formation for each of the multi-value gradation value data and each pixel based on such a concept.

  FIG. 60 is an explanatory diagram conceptually showing an example of the dot number data conversion table used here. In this dot number data conversion table, as shown in the figure, data indicating the dot type formed in each pixel of the eight pixels is set in association with the combination of the multi-value quantization result value and the classification number. Has been. Here, this data is referred to as dot data. Referring to the dot number data conversion table shown in FIG. 60, the corresponding dot data can be immediately acquired from the combination of the multi-value gradation value data and the classification number. For example, if the classification number is “i” and the multi-value gradation value data is “j”, the dot data is DD (i, j). The dot data obtained in this way includes information regarding the presence or absence of dot formation for each of the eight pixels.

  FIG. 61 is an explanatory diagram showing an example of the data structure of dot data set in the dot number data conversion table used here. FIG. 61A illustrates an example of dot data. FIG. 61B illustrates an example of an actual dot formation image.

  As shown in FIG. 61A, the dot data is 16-bit data composed of 8 sets of 2-bit data. Here, one dot data is composed of eight sets of data because one multi-value gradation value data includes information on eight pixels. Therefore, for example, when one multi-value gradation value data includes information on 16 pixels as in the case of the “4 × 4 mode” of the present embodiment, one dot data has 16 sets. It will consist of data. In addition, although not in the present embodiment, when one multi-value gradation value data includes information on four pixels, one dot data is composed of four sets of data.

  As shown in FIG. 61, eight sets of data constituting dot data are associated with pixels at predetermined positions in the eight pixels, respectively. For example, the first set of data at the head of the dot data shown in FIG. 61A corresponds to the pixel at the upper left corner of the eight pixels as shown in FIG. 61B. The second set of data from the top of the dot data corresponds to the second pixel from the left in the upper row of the eight pixels. In this way, the eight sets of data constituting the dot data are associated in advance with the pixels at predetermined positions among the eight pixels.

  The contents of each set of data represent the types of dots formed on the corresponding pixels. That is, the 2-bit data “11” means that a large dot is formed. The 2-bit data “10” means that a medium dot is formed, “01” means that a small dot is formed, and “00” means that a dot is not formed. As can be seen from the above description, the dot data illustrated in FIG. 61A forms a large dot in the upper left corner of the eight pixels, and forms a middle dot in the third pixel from the upper left. It has come to express. The dot data indicates that a small dot is formed in the second pixel from the left in the lower row, and a medium dot is formed in the pixel at the lower right corner of the eight pixels. Further, this dot data represents that dots are not formed in other pixels.

  By referring to such a dot number data conversion table, it is possible to quickly determine the presence or absence of dot formation for each of the eight pixels based on the classification number and the multi-value gradation value data. is there.

  In this embodiment, in addition to such a dot number data conversion table, a dedicated dot number data conversion table is required for each of the “2 × 4 mode” and the “4 × 4 mode”.

=== Other Embodiments ===
As described above, the printing apparatus such as the ink jet printer according to the present invention has been described based on one embodiment. However, the above embodiment is for facilitating understanding of the present invention, and the present invention is limited. It is not for interpretation. The present invention can be changed or improved without departing from the gist thereof, and needless to say, the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About the encoder>
In the above-described embodiment, as an encoder, a multi-value processing unit (multi-value processing unit) that generates multi-value gradation value data by performing multi-value processing on the gradation value of each pixel of the first image data. However, the “encoder” is not limited to such a multi-value processing unit. That is, any type of encoder may be used as long as it encodes the pixel data of the first image data and generates a plurality of encoded data.

<About the decoder>
In the above-described embodiment, as a decoder, multi-value gradation value data is converted into dot number data representing the number of dots, and based on this dot number data, whether or not dots are individually formed for one or more pixels. A dot formation data generation unit that generates dot formation data using at least some of the one or more pixels determined to have dot formation determined as pixels constituting the second image. Although (dot formation data generation unit) has been described as an example, the “decoder” is not limited to such a dot formation data generation unit. In other words, any type of decoder can be used as long as it decodes the encoded data generated by the encoder, generates pixel data of at least one pixel for each encoded data, and outputs the second image data. It does not matter.

<Decode controller>
In the above-described embodiment, the controller 414 provided in the dot formation data generation unit (dot formation data generation unit 184) has been described as an example of the decode controller. It is not restricted to such a controller 414. That is, any type of controller may be used as long as the decoder instructs the order of the encoded data to be decoded.

<About multi-value processing>
In the embodiment described above, multi-value gradation value data is generated using a multi-value conversion table. However, when multi-value gradation value data is always generated using such a multi-value conversion table. Is not limited. That is, multi-value gradation value data may be generated by calculation or the like without using a table.

<Dot count data conversion process>
In the above-described embodiment, the multi-value gradation value data is converted into the dot number data using the dot number data conversion table. However, the multi-value gradation value is not necessarily converted using such a dot number data conversion table. There is no need to convert the data to dot count data. That is, the dot number data may be acquired by calculation or the like without using a table.

<About multi-value gradation value data>
In the above-described embodiment, the multi-value gradation value data is generated as 5-bit data of 32 gradations. However, in the present invention, it is not always necessary to generate such data with the number of bits. That is, the number of bits of the multi-value gradation value data is appropriately set according to the number of stages when the multi-value processing unit (multi-value processing unit) multi-values, that is, the number of multi-value levels. The multi-value gradation value data may be generated as data of other number of bits.

<About dot count data>
In the above-described embodiment, the dot number data is encoded to indicate not only the number of dots to be formed but also the size of each dot to be formed (that is, “small dot”, “medium dot”, “large dot”). However, the present invention does not necessarily need to be such data. That is, the dot number data only needs to indicate the number of dots of at least one kind of size, and does not necessarily have to be data representing other information such as the dot size.

<Resolution of output image>
In the embodiment described above, the resolution of the output image is “1 × 1 mode”, “2 × 1 mode”, “1 × 2 mode”, “2 × 2 mode”, and “4 × 2 mode”. ”,“ 2 × 4 mode ”, and“ 4 × 4 mode ”, but the present invention is not necessarily limited to such a resolution. That is, the resolution of the output image may be set to other resolutions, and is arbitrarily set.

<About one or more pixels>
In the above-described embodiment, the dot formation data generation unit (dot formation data generation unit) determines whether dot formation is performed or not, and determines whether dot formation is performed individually for each of eight pixels as “one or more pixels”. However, this “one or more pixels” is not necessarily limited to the case where dot formation is individually determined for eight pixels as described above, and dot formation is individually performed for seven or less pixels. The presence or absence of dot formation may be determined, and the presence or absence of dot formation may be determined individually for nine or more pixels.

<About the multi-value processor>
In the above-described embodiment, the multi-value processing unit is provided in the ASIC 95 as a multi-value processing unit. However, in the multi-value processing unit, the multi-value processing unit is not necessarily provided in such an ASIC 95. Not limited. That is, for example, instead of the ASIC 95, it may be configured separately by a dedicated processing circuit or the like, or may be configured by a component having a function of processing in software.

<Dot formation data generation unit>
In the above-described embodiment, the dot formation data generation unit is provided in the ASIC 95 as the dot formation data generation unit. However, the dot formation data generation unit does not necessarily have such an ASIC 95 in this way. However, the present invention is not limited to this. That is, for example, instead of the ASIC 95, it may be configured separately by a dedicated processing circuit or the like, or may be configured by a component having a function of processing in software.

<About memory>
In the above-described embodiment, the SDRAM is exemplified as the “memory”. However, the “memory” here is not limited to such an SDRAM. In other words, other types of memory other than SDRAM, for example, rewritable volatile memory such as SRAM and EEPROM, etc. may be used, and in addition to this, if it is a hard disk drive or other data storage device capable of rewriting data, Any device is included in the “memory” here.

<Image processing device>
In the above-described embodiment, as an image processing apparatus, a scanner function for reading an image from a document and generating image data and printing on various media such as printing paper based on print data sent from a host computer (not shown). In the above description, a scanner / printer / copier combined apparatus (hereinafter also referred to as an SPC combined apparatus) having a printer function for printing and a local copy function for copying an image read from an original on a medium has been described. The image processing apparatus here is not limited to such a composite apparatus. In other words, it may be a normal printing apparatus that does not have a scanner function for reading an image from a document to generate image data and a local copy function for printing an image read from a document on a medium and copying it. An apparatus that does not have a function and that simply processes image data may be used. In addition, any device that processes image data and generates dot formation data for an output image is also included in the image processing device referred to herein.

<About printing devices>
In the above-described embodiment, as a printing apparatus, an image processing apparatus, a scanner function that reads an image from a document and generates image data, and a print sheet or the like based on print data sent from a host computer (not shown) Take as an example a scanner / printer / copy copier (hereinafter also referred to as an SPC copier) having a printer function for printing on various media and a local copy function for printing an image read from an original on a medium and copying it. As described above, the printing apparatus here is not limited to such a composite apparatus. In other words, there is no need for a scanner function for reading an image from a document to generate image data and a local copy function for printing an image read from a document on a medium and copying it, and printing sent from a host computer (not shown). A printing apparatus having only a printer function for printing on various media such as printing paper based on data may be used.

  In the above-described embodiment, the case of the ink jet printer 1 as described above has been described as an example of the printing apparatus. Any other printing device that has a printing function, such as a printer that does not discharge ink, such as a dot impact printer, a thermal transfer printer, or a laser beam printer. I do not care.

The perspective view explaining the appearance of a scanner / printer / copier combined apparatus. FIG. 2 is a perspective view when a cover of a scanner unit of the multifunction device of FIG. 1 is opened. The perspective view which shows the printing part of the composite apparatus of FIG. FIG. 2 is an explanatory diagram illustrating configurations of a scanner unit and a printer unit of the multifunction apparatus of FIG. 1. Sectional drawing explaining the conveyance part of a printer part. Explanatory drawing explaining the operation panel of the compound apparatus of FIG. Explanatory drawing which shows the arrangement | sequence of the nozzle of a head. FIG. 3 is a diagram illustrating an example of a head drive circuit. It is a timing chart of each signal. 6 is a flowchart for explaining an example of printing processing. The figure explaining an example of a structure of the conventional control part. The figure explaining an example of a structure of the control part of this embodiment. The flowchart explaining an example of the process sequence of the multi-value process of a multi-value process unit. Explanatory diagram conceptually showing an example of a multi-value table Explanatory drawing explaining the relationship between the gradation value of a pixel, and multi-value gradation value data. Explanatory drawing explaining the setting method of the classification number in "1x1 mode". Explanatory drawing explaining the setting method of the classification number in "2 * 1 mode". Explanatory drawing explaining the setting method of the classification number in "1x2 mode". Explanatory drawing explaining the setting method of the classification number in "2 * 2 mode". Explanatory drawing explaining the setting method of the classification number in "4x2 mode". Explanatory drawing of the outline | summary of the multi-value process actually implemented. 5 is a flowchart illustrating an example of a processing procedure of a dot formation data generation unit. FIG. 6 is an explanatory diagram of an example of a dot number data conversion table. FIG. 6 is an explanatory diagram illustrating an example of a correspondence relationship between dot number data and the number and size of dots. 18A illustrates an example of an order value matrix with a classification number “1”, FIG. 18B illustrates an example of an order value matrix with a classification number “2”, and FIG. 18C illustrates an order value with a classification number “3”. An example of the matrix is described. Explanatory drawing of an example of the procedure which determines the presence or absence of dot formation. FIG. 20A is an explanatory diagram of clipping of the upper left corner pixel, FIG. 20B is an explanatory diagram of clipping of the second pixel from the left in the upper stage, and FIG. 20C is clipping of the second pixel from the upper right. 20D is an explanatory diagram of cutting out the pixel in the upper right corner, FIG. 20E is an explanatory diagram of cutting out the pixel in the lower left corner, and FIG. 20F is the second pixel from the left in the lower row FIG. 20G is an explanatory diagram of cutting out the second pixel from the lower right, and FIG. 20H is an explanatory diagram of cutting out the pixel at the lower right corner. Explanatory drawing of the position of the pixel in CMYK image data. FIG. 22A is an explanatory diagram of cutting out the first and second pixels from the left in the upper stage, FIG. 22B is an explanatory diagram of cutting out the first and second pixels from the upper, right, and FIG. FIG. 22D is an explanatory diagram of cutting out the first and second pixels from the lower left, and FIG. 22D is an explanatory diagram of cutting out the first and second pixels from the lower right. Explanatory drawing of the position of the pixel in CMYK image data. FIG. 24A is an explanatory diagram in the case of cutting out the upper and lower two pixels in the first column from the left, FIG. 24B is an explanatory diagram in the case of cutting out the upper and lower two pixels in the second column from the left, and FIG. FIG. 24D is an explanatory diagram in the case of cutting out the upper and lower two pixels in the second column from the right, and FIG. 24D is an explanatory diagram in the case of cutting out the upper and lower two pixels in the first column from the right. Explanatory drawing of the position of the pixel in CMYK image data. FIG. 26A is an explanatory diagram when cutting out four pixels in the left half, and FIG. 26B is an explanatory diagram when cutting out four pixels in the right half. Explanatory drawing of the position of the pixel in CMYK image data. Explanatory drawing of the cutting-out method of the pixel in "4x2 mode". Explanatory drawing of an example of the dot number data conversion table of “2 × 4 mode”. Explanatory drawing of an example of the order value matrix of "2x4 mode." Explanatory drawing of the determination method of the presence or absence of dot formation in "2 * 4 mode". Explanatory drawing of an example of the dot number data conversion table of "4x4 mode". FIG. 4 is an explanatory diagram illustrating an example of a correspondence relationship between dot number data of “4 × 4 mode” and information regarding the number and size of dots to be formed, which is represented by the dot number data. Explanatory drawing of an example of the order value matrix of "4x4 mode." Explanatory drawing of the determination method of the presence or absence of dot formation in "4x4 mode". Explanatory drawing of the outline | summary of the actual production | generation process of the data for dot formation. Explanatory drawing of the production | generation method of the data for dot formation in "1x1 mode". Explanatory drawing of the production | generation method of the data for dot formation in "2 * 1 mode". Explanatory drawing of the production | generation method of the data for dot formation in "1x2 mode". Explanatory drawing of the production | generation method of the data for dot formation in "2 * 2 mode". Explanatory drawing of the production | generation method of the data for dot formation in "4x2 mode". Explanatory drawing of the production | generation method of the data for dot formation in "2 * 4 mode". Explanatory drawing of the production | generation method of the data for dot formation in "4x4 mode". Explanatory drawing of area allocation of the memory space of SDRAM. FIG. 3 is an explanatory diagram illustrating an example of a configuration of a dot formation data generation unit. Explanatory drawing of an example of the production | generation process of the data for dot formation by the data generation unit for dot formation. Explanatory drawing of the other example of the production | generation process of the data for dot formation by the data generation unit for dot formation. Explanatory drawing of the other example of the production | generation process of the data for dot formation by the data generation unit for dot formation. Explanatory drawing of an example when multi-value gradation value data cannot be acquired regularly. Explanatory drawing of an example of the acquisition method of multi-value gradation value data. Explanatory drawing of the other example of the acquisition method of multi-value gradation value data. Explanatory drawing of the data reading from SDRAM. Explanatory drawing which expanded and illustrated a part of dither matrix. Explanatory drawing explaining the determination method of the presence or absence of dot formation by a dither matrix. FIG. 47A is an explanatory diagram of unit blocks set in the dither matrix, FIG. 47B is an explanatory diagram of classification numbers set in the dither matrix, and FIG. 47C is an explanatory diagram in the case where the dither matrix is applied to image data. . 48A is an explanatory diagram of the position of the pixel of interest on the CMYK image data, FIG. 48B is an explanatory diagram of an example of a method of applying the dither matrix to the CMYK image data, and FIG. 48C specifies a unit block to which the pixel of interest belongs. It is explanatory drawing of a method. The flowchart explaining the outline | summary of a halftone process. Explanatory drawing of a dot density conversion table. Explanatory drawing explaining the outline | summary of a halftone process. The flowchart explaining an example of the setting procedure of a multi-value table. 9 is a flowchart for explaining an example of a procedure for setting a dot number data conversion table. 54A is an explanatory diagram of the classification number set in the dither matrix, FIG. 54B is an explanatory diagram of a generation procedure of the order value matrix of the classification number “1”, and FIG. 54C is an order value matrix of the classification number “2”. It is explanatory drawing of a production | generation procedure. Explanatory drawing of the outline | summary of the data generation process for dot formation. Explanatory drawing explaining an example of the multi-value conversion table of another type. Explanatory drawing explaining an example of the data formation process for dot formation by another method. Explanatory drawing explaining an example of the correspondence table of dot number data and intermediate data. 59A is an explanatory diagram for explaining the outline of intermediate data, FIG. 59B is an explanatory diagram of a method for reading 2-bit data from the intermediate data, and FIG. 59C is a diagram for explaining how 2-bit data is shifted by shifting the intermediate data. It is explanatory drawing of the method of performing reading. Explanatory drawing explaining an example of the dot number data conversion table of another type. FIG. 61A is an explanatory diagram of an example of dot data, and FIG. 61B is an explanatory diagram of an example of an actual dot formation image.

Explanation of symbols

1 SPC multifunction device, 2 operation panel, 3 paper discharge unit, 4 paper feed unit, 5 document,
7 discharge tray, 8 paper feed tray, 10 scanner unit, 11 document table,
12 Document plate cover, 13 Paper feed roller, 14 Platen, 15 Transport motor,
17A transport roller, 17B paper discharge roller, 18A free roller,
18B free roller, 21 head, 24 drive mechanism, 30 printer section,
32 opening, 34 hinge, 36 transport mechanism, 41 carriage,
42 Carriage motor, 44 pulley, 45 timing belt,
46 guide rails, 49 control units, 50 control units,
51 linear encoder code plate, 52 detector, 53 paper detection sensor,
56 Rotary encoder, 60 Scanner carriage,
62 drive mechanism, 64 guide, 66 exposure lamp, 68 mirror,
70 lens, 72 CCD sensor, 74 timing belt,
75 pulleys, 76 pulleys, 77 drive motors,
80 liquid crystal display, 81 information lamp, 82 power button,
83 Various setting buttons, 84 Copy mode buttons,
85 Memory card print mode button, 86 Film print mode button,
87 Scan mode button, 88 Feed / discharge button,
89A OK button, 89B Cancel button, 89C Save button,
89D color copy button, 89E monochrome copy button,
89F stop button, 89G cross button, 89H menu button,
90 CPU, 92 memory, 94 ASIC,
95 ASIC, 96 SDRAM, 98 CPU bus,
100 head unit, 102 SDRAM, 102A area,
102B region, 102C region, 102D region, 102E region,
102F region, 102G region, 102H region, 102I region,
103 SDRAM controller,
104 Scanner control unit, 106 Resizing unit,
108 binarization processing unit, 110 interlace processing unit,
112 image buffer unit, 114 bus controller,
116 head control unit, 118 USB interface,
120 line buffer, 122 resize buffer,
124 interlace buffer, 126 image buffer,
127 image buffer, 128 local bus, 130 SRAM,
132 image buffer, 133 image buffer,
134 Image buffer,
136 lookup table, 140 host computer,
180 color conversion processing unit, 182 multi-value processing unit,
184 dot formation data generation unit,
186 multi-value gradation value data buffer,
188 Multi-value gradation value data buffer, 190 dot formation data buffer,
211Y yellow nozzle row, 211M magenta nozzle row,
211C cyan nozzle row, 211K black nozzle row,
220 drive circuit, 221 original drive signal generator, 222 mask circuit,
400 generation circuit, 402 first buffer, 404 second buffer,
406 third buffer, 410 dot count data conversion table,
412 Order value matrix, 414 controller

Claims (16)

(A) Output based on the classification number classified according to the position of each pixel constituting the image represented by the image data and the gradation value of each pixel constituting the image represented by the image data A multi-value processing unit that generates multi-value gradation value data that has been multi-valued according to the resolution of the image;
(B) a dot number data conversion table for converting the multi-value gradation value data into dot number data representing the number of dots to be formed and the dot size, and the order in which the dots to be formed are to be formed. Based on the set dot formation order data, generate dot data in which the positions and dot sizes of the dots to be formed are determined, and associate the pixels in the dot data with the pixels constituting the image data A dot formation data generator for generating dot formation data,
With
The dot formation data generation unit generates the dot formation data by cutting out a predetermined number of pixels in the dot data from the dot data according to the resolution of the dot formation data. It has a head that forms dots by discharging liquid based on head drive data,
The image processing apparatus according to claim 1, wherein the dot formation data generation unit generates the dot formation data in an order corresponding to the head drive data to be transmitted to the head. A multi-value conversion table in which the gradation value and the multi-value gradation value data are associated with each other;
The image processing apparatus according to claim 1 , wherein the multi-value processing unit generates the multi-value gradation value data by referring to the multi-value table. The multi-value processing unit multi-values each tone value of each pixel constituting the image represented by the image data based on the image data according to the resolution of the output image. The image processing apparatus according to claim 3 , wherein the multi-value gradation value data is generated. 5. The image processing apparatus according to claim 3, wherein the multi-value gradation value data is generated by the multi-value processing unit as data having a predetermined number of bits. The dot formation data generating unit converts the multi-value gradation value data generated by the multi-value processing unit into dot number data representing the number of dots, and based on the dot number data, 1 or more Whether or not dot formation is individually determined for each of the pixels, and at least some of the one or more pixels determined to have dot formation or not are used as pixels constituting the output image and the resolution generating a dot formation data of the output image as the image data of the output image, the image processing apparatus according to any one of claims 3-5. A dot number data conversion table in which the multi-value gradation value data and the dot number data are associated with each other;
The image processing apparatus according to claim 6 , wherein the dot formation data generation unit converts the multi-value gradation value data into the dot number data by referring to the dot number data conversion table. . 8. The image processing apparatus according to claim 6, wherein the dot formation data generation unit determines whether or not to form dots individually for a predetermined number of pixels based on the dot number data. 9. 9. The image processing apparatus according to claim 6 , wherein the dot number data includes data related to a dot size in addition to the number of dots. The dot formation data generation unit determines whether or not to form dots individually for the one or more pixels based on dot formation order data indicating the dot formation order in addition to the dot number data. The image processing apparatus according to claim 6 . The number of pixels used as pixels constituting the output image among the one or more pixels for which the presence or absence of the dot formation is determined by the dot formation data generation unit is the resolution of the second image. The image processing apparatus according to claim 6 , wherein the image processing apparatus is different depending on the image processing apparatus. The position of a pixel used as a pixel constituting the output image among the one or more pixels for which the presence or absence of the dot formation is determined by the dot formation data generation unit is the multi-value gradation value data. 12. The image processing apparatus according to claim 6 , wherein the image processing apparatus differs depending on a position of a pixel corresponding to a gradation value subjected to multi-value processing when generating. (A) Output based on the classification number classified according to the position of each pixel constituting the image represented by the image data and the gradation value of each pixel constituting the image represented by the image data Generating multi-value gradation value data subjected to multi-value processing according to the resolution of the image;
(B) a dot number data conversion table for converting the multi-value gradation value data into dot number data representing the number of dots to be formed and the dot size, and the order in which the dots to be formed are to be formed. Based on the set dot formation order data, generate dot data in which the positions and dot sizes of the dots to be formed are determined, and associate the pixels in the dot data with the pixels constituting the image data Generating data for dot formation,
Including
The dot formation data is generated by cutting out a predetermined number of pixels in the dot data from the dot data in accordance with the resolution of the dot formation data. (A) Output based on the classification number classified according to the position of each pixel constituting the image represented by the image data and the gradation value of each pixel constituting the image represented by the image data Generating multi-value gradation value data subjected to multi-value processing according to the resolution of the image;
(B) a dot number data conversion table for converting the multi-value gradation value data into dot number data representing the number of dots to be formed and the dot size, and the order in which the dots to be formed are to be formed. Based on the set dot formation order data, generate dot data in which the positions and dot sizes of the dots to be formed are determined, and associate the pixels in the dot data with the pixels constituting the image data Generating data for dot formation,
And execute
A program for generating the dot formation data by cutting out a predetermined number of pixels in the dot data from the dot data in accordance with the resolution of the dot formation data. (A) Output based on the classification number classified according to the position of each pixel constituting the image represented by the image data and the gradation value of each pixel constituting the image represented by the image data A multi-value processing unit that generates multi-value gradation value data that has been multi-valued according to the resolution of the image;
(B) a dot number data conversion table for converting the multi-value gradation value data into dot number data representing the number of dots to be formed and the dot size, and the order in which the dots to be formed are to be formed. Based on the set dot formation order data, generate dot data in which the positions and dot sizes of the dots to be formed are determined, and associate the pixels in the dot data with the pixels constituting the image data A dot formation data generation unit for generating dot formation data,
A printing unit that performs printing on the medium based on the dot formation data;
With
The dot formation data generation unit generates the dot formation data by cutting out a predetermined number of pixels in the dot data from the dot data according to the resolution of the dot formation data. The printing apparatus according to claim 15 , further comprising an image reading unit that reads an image from a document and generates the image data.