JP2016155298A - Image processing device and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate record data for enabling an image with hardly visually recognized deterioration in a granular feeling and uniformity to be recorded.SOLUTION: It is selected which is used, in each pixel, to perform processing between a first mask pattern group and a second master pattern group in which ink is allowed to be discharged as many as a number that is larger than the number of pixels to which ink is allowed to be discharged in the first mask pattern group.SELECTED DRAWING: Figure 13

Description

  The present invention relates to an image processing apparatus and an image processing method.

  This is a direction that intersects the scanning direction with a recording scan that ejects ink while moving a recording head in which a plurality of recording ejection openings for ejecting ink are arranged relative to the unit area of the recording medium in the scanning direction. 2. Description of the Related Art An image recording apparatus that records an image by repeatedly performing sub-scanning that transports a recording medium in the transport direction is known. In such an image recording apparatus, a so-called multi-pass recording method is known in which an image is formed by performing a plurality of recording scans on a unit area.

  In the conventional multi-pass printing method, image data that determines ink ejection or non-ejection for each of the plurality of pixels is generated by quantizing the gradation data indicating the gradation value of the image in the plurality of pixels, and the image data Is distributed to a plurality of scans to generate print data used for printing in a plurality of scans. It is also known to use an index pattern that defines the position and number of pixels that eject ink in accordance with the gradation value in the quantization process. Furthermore, it is known to use a plurality of mask patterns that correspond to a plurality of scans in the distribution process and determine whether ink ejection is permitted or not permitted for each pixel.

  Here, Patent Document 1 discloses that recording data is generated so that all gradation values that gradation data can represent can be expressed by associating each of an index pattern and a plurality of mask patterns with each other. . More specifically, 4-bit data that can represent 9 levels of gradation values is used as the gradation data, and the total number of times is 0 to 8 for four pixels according to each gradation. It is described that print data that ejects ink is generated.

JP 2012-153118 A

  However, when an index pattern and a mask pattern that are associated with each other as described in Patent Document 1 are used, there is a possibility that the graininess and the deterioration of uniformity are conspicuous in the obtained image.

  FIG. 1 is a diagram schematically showing recording data generated based on gradation data representing each of nine gradation values by applying the index pattern and mask pattern described in Patent Document 1. In FIG. FIGS. 1A to 1I are diagrams showing recording data generated based on gradation data whose gradation values are level 0 to level 8, respectively.

  As can be seen from FIGS. 1A to 1I, according to Patent Document 1, it is possible to generate print data in which the number of ink ejections is varied for each tone value of the tone data. For example, when the gradation value of the gradation data is level 1, recording data is generated so that ink is ejected only once to the upper left pixel as shown in FIG. If the gradation value of the gradation data is level 2, recording data is generated so that ink is ejected twice to the lower left pixel as shown in FIG. Further, when the gradation value of the gradation data is level 8, as shown in FIG. 1 (i), ink is applied once to the upper left pixel, twice to the lower left and upper right pixels, and three times to the lower right pixel. Recording data that ejects ink eight times in total is generated.

  However, when the technique described in Patent Document 1 is used, a desired image quality may not be obtained at some gradation levels.

  For example, according to the recording data generated from the gradation data having the gradation value of level 2 using the technique of Patent Document 1, the ink is ejected twice to one pixel as shown in FIG. It becomes. In other words, ink is ejected twice in the pixel area corresponding to the lower left pixel even though ink is not ejected once in the pixel area on the recording medium corresponding to the three pixels other than the lower left pixel. Form large dots. As a result, an image with a noticeable graininess is recorded on the recording medium due to the large dots.

  Further, according to the recording data generated from the gradation data having the gradation value of level 8 using the technique of Patent Document 1, as shown in FIG. 1 (i), only once for the upper left pixel. Ink is not ejected. Thereby, even when the highest gradation value is expressed, a desired density may not be obtained in the pixel. Further, since pixels that eject ink only once and pixels that eject ink three times coexist, uniformity may be reduced and density unevenness may occur.

  To solve such a problem by associating the index pattern and the mask pattern disclosed in Patent Document 1, it is difficult to realize the problem due to the respective restrictions.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a recording data generation method capable of recording an image in which a graininess and a decrease in uniformity are difficult to be visually recognized. It is.

  In view of the above, the present invention provides a method for applying ink to each of pixel regions corresponding to a plurality of pixels in each unit region in each of a plurality of relative scans with respect to the unit region on the recording medium of the recording head for ejecting ink. An image processing apparatus that generates recording data represented by 1-bit information for each pixel that is used for each of the plurality of scans, which defines ejection or non-ejection, and includes at least the plurality of pixel regions for each pixel. First acquisition means for acquiring image data represented by n (n ≧ 2) bit information relating to the number of ink discharges for each, and whether or not ink discharge is allowed or not for each pixel is determined. Of the plurality of mask pattern groups including at least the first and second mask pattern groups represented by 1-bit information, one for each pixel. Based on selection means for selecting a mask pattern group, the image data acquired by the first acquisition means, and one mask pattern group selected for each pixel by the selection means. First generation means for generating the print data used in each of a plurality of scans, and the number of pixels for which ink ejection is permitted in the second mask pattern group is the first number More than the number of pixels for which ejection of ink is determined in the mask pattern group, the selection means (i) ink indicated by n-bit information representing the image data acquired by the first acquisition means The first mask pattern group is selected for a pixel whose number of ejections is the first number, and (ii) the image data acquired by the first acquisition unit is displayed. In the pixel number of times of ejection of the ink indicated by the n-bit information is the second number of more than the first number and selecting the second mask pattern group.

  According to the image processing apparatus and the image processing method of the present invention, it is possible to provide a recording data generation method capable of recording an image in which a graininess and a decrease in uniformity are difficult to be visually recognized.

It is a schematic diagram which shows the image recorded according to the conventional method. 1 is a perspective view of an image recording apparatus applied in an embodiment. It is a side view of the internal mechanism of the image recording device applied in an embodiment. It is a schematic diagram of the recording head applied in the embodiment. It is a figure for demonstrating a general multipass recording system. It is a schematic diagram of the mask pattern applied with a general multipass printing method. It is a schematic diagram which shows the control system of the recording in embodiment. It is a block diagram which shows the process of the data in embodiment. It is a figure which shows the index pattern applied in embodiment. It is a flowchart which shows the process of the mask process in embodiment. It is a figure which shows the mask pattern applied in embodiment. It is a figure which shows the mask pattern applied in embodiment. It is a figure for demonstrating the process of the gradation data in embodiment. It is a schematic diagram which shows the image recorded according to embodiment. It is a figure which shows the index pattern applied in embodiment. It is a flowchart which shows the process of the mask process in embodiment. It is a figure which shows the mask pattern applied in embodiment. It is a figure for demonstrating the process of the gradation data in embodiment. 1 is a perspective view of an image recording apparatus applied in an embodiment.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 2 is a perspective view partially showing an internal configuration of an image recording apparatus (hereinafter also referred to as a recording apparatus or a printer) 1000 according to the first embodiment of the present invention. FIG. 3 is a sectional view partially showing an internal configuration of the image recording apparatus 1000 according to the first embodiment of the present invention.

  A platen 2 is disposed inside the image recording apparatus 1000, and a plurality of suction holes 34 are formed in the platen 2 in order to prevent the recording medium 3 from adsorbing and floating. The suction hole 34 is connected to a duct, and a suction fan 36 is disposed at the lower part of the duct. The suction fan 36 operates to suck the recording medium 3 to the platen 2.

  The carriage 6 is supported by a main rail 5 installed extending in the paper width direction, and is configured to reciprocate in the X direction (scanning direction). The carriage 6 is equipped with an ink jet recording head 7 which will be described later. The recording head 7 can employ various recording methods such as a thermal jet method using a heating element and a piezo method using a piezoelectric element. The carriage motor 8 is a driving source for moving the carriage 6 in the X direction, and the rotational driving force is transmitted to the carriage 6 by the belt 9.

  The recording medium 3 is fed by being unwound from a medium 23 wound in a roll shape. The recording medium 3 is conveyed on the platen 2 in the Y direction (conveying direction) intersecting the X direction. The recording medium 3 is nipped between the pinch roller 16 and the conveyance roller 11 at the tip, and is conveyed when the conveyance roller 11 is driven. The recording medium 3 is sandwiched between a roller 31 and a discharge roller 32 downstream of the platen 2 in the Y direction, and the recording medium 3 is wound around a winding roller 24 via a turn roller 33.

  FIG. 4 shows a recording head used in this embodiment.

  The recording head 7 includes six ejection port arrays 22Y that eject ink of yellow (Y), magenta (M), light magenta (Lm), cyan (C), light cyan (Lc), and black (Bk), respectively. 22M, 22Lm, 22C, 22Lc, 22Bk (hereinafter, one of these discharge port arrays is also referred to as a discharge port array 22) is arranged in this order in the X direction. These ejection port arrays 22 are configured by arranging 1280 ejection ports 30 for ejecting the respective inks in the Y direction (arrangement direction) at a density of 1200 dpi. Here, the recording head is described in which the ejection ports 30 located adjacent to each other in the Y direction are arranged at positions shifted from each other in the X direction. However, 1280 ejection ports are linearly formed without being displaced. It may be arranged. Here, the amount of ink ejected at one time from one ejection port 30 in the present embodiment is about 4.5 ng.

  These ejection port arrays 22K, 22C, 22M, 22Y, 22Lc, and 22Lm are connected to ink tanks (not shown) that store the corresponding ink, respectively, and ink is supplied. Note that the recording head 7 and the ink tank used in the present embodiment may be configured integrally, or may be configured such that each can be separated.

  In this embodiment, an image is recorded in accordance with a multi-pass recording method in which recording is performed by scanning the recording head a plurality of times with respect to a unit area on the recording medium.

  FIG. 5 is a diagram for explaining a general multipass printing method when printing is performed in a unit area on a printing medium by four printing scans.

  FIG. 6 is a diagram for explaining a mask pattern applied in each printing scan in the above-described multipass printing method.

  Each ejection port 30 provided in the ejection port array 22 that ejects ink is divided into four ejection port groups 201, 202, 203, and 204 along the Y direction.

  Each mask pattern 221, 222, 223, and 224 is configured by arranging a plurality of print permitting pixels that determine allowance of ejection of a plurality of inks and non-recording permitting pixels that determine non-permitance of ink ejection. In FIG. 6, pixels that are blacked out represent recordable pixels, and pixels that are represented by white dots represent non-recordable pixels. In the print permitting pixel, when the input image data is image data representing ink discharge, it is set as print data for discharging ink. In the non-recording permissible pixel, even when image data representing ink ejection is input, the recording data does not eject ink.

  Note that the print permitting pixels in the mask patterns 221, 222, 223, and 224 are arranged at positions that are different from each other and that have a relationship in which the respective logical sums are all pixels.

  Hereinafter, an example in which an image having a duty of 100% (hereinafter also referred to as a solid image) is formed on a recording medium will be described.

  In the first printing scan (one pass), ink is ejected from the ejection port group 201 to the area 211 on the recording medium 3 in accordance with the mask pattern 221. As a result, ink is ejected onto the recording medium at the position indicated by black in FIG.

  Next, the recording medium 3 is conveyed relative to the recording head 7 by a distance of L / 4 from the upstream side in the Y direction to the downstream side.

  Thereafter, the second recording scan (two passes) is performed. In the second printing scan, ink is ejected from the ejection port group 202 to the mask pattern 222 to the area 211 on the recording medium, and from the ejection port group 203 to the area 212 according to the mask pattern 221. As a result of the second recording scan, an image as shown in black in FIG. 6B is formed on the recording medium 3.

  Thereafter, the recording scan of the recording head 7 and the relative conveyance of the recording medium 3 are repeated alternately. As a result, after the fourth printing scan (four passes) is performed, ink ejection is completed in the pixel region D corresponding to all pixels in the region D 211 of the recording medium 3, and a solid image is formed. The

  FIG. 7 is a block diagram showing a schematic configuration of a control system in the present embodiment. The main control unit 300 includes a CPU 301 that executes processing operations such as calculation, selection, discrimination, and control, a ROM 302 that stores a control program to be executed by the CPU 301, a RAM 303 that is used as a buffer for recording data, and an input / output Port 304 etc. are provided. The ROM 303 also stores a mask pattern and the like which will be described later. The input / output port 304 is connected to drive circuits 305, 306, 307, and 308 such as a conveyance motor (LF motor) 309, a carriage motor (CR motor) 310, the recording head 7, and an actuator in the cutting unit. . Further, the main control unit 300 is connected to a PC 312 which is a host computer via an interface circuit 311.

  The process of processing image data in this embodiment will be described in detail below.

  FIG. 8 is a block diagram for explaining a data processing process in the present embodiment.

  The application J0001 of the PC 312 is used to create image data to be recorded by the printer 1000. The image data created by the application J0001 is transmitted to the printer driver 103 when recording.

  The printer driver 103 executes a pre-stage process J0002, a post-stage process J0003, a γ correction J0004, a quantization process J0005, and a gradation data generation process J0006, respectively, on the created image data.

  In the pre-stage process J0002, the color gamut conversion for converting the color gamut of the display of the PC 312 into the color gamut of the printer 1000 is performed. By using a three-dimensional lookup table, image data R, G, and B each represented by 8-bit information is converted into 8-bit data R, G, and B in the printer color gamut. .

  In post-processing J0003, the color that reproduces the converted color gamut is decomposed into the ink color gamut. Obtain 8-bit data C, M, Y, K, Lc, and Lm corresponding to the combination of inks for reproducing the colors represented by the 8-bit data R, G, and B in the print color gamut obtained in the preceding process J0002. Process.

  In γ correction J0004, γ correction is performed for each of 8-bit data C, M, Y, K, Lc, and Lm obtained by color separation. Conversion is performed so that each of the 8-bit data C, M, Y, K, Lc, and Lm obtained in the post-processing J0003 is linearly associated with the gradation characteristics of the printer.

  In the quantization processing J0005, each of the 8-bit data C, M, Y, K, Lc, and Lm obtained by the γ correction J0004 is represented by m-bit data C and M represented by m (m <8) -bit information. , Y, K, Lc, and Lm are converted into a quantization process. As the quantization means, a density pattern method, a dither method, an error diffusion method, or the like is preferably used.

  In the gradation data creation process J0006, the mbit data C, M, K, Y, Lc, and Lm obtained in the quantization process J0005 are attached to the contents of the print control data and the like as m-bit information. Create gradation data to be represented. The print control data includes recording medium information, recording quality information, and the like. The gradation data generated as described above is supplied to the printer 1000. Note that. This m-bit gradation data can express gradation values of 2 m (2 ^ m) at the maximum.

  The printer 1000 performs index processing J0007 and mask processing J0008 on the gradation data input from the PC 312.

  First, in the index processing J0007, n (2 ≦ n <m) bits of information for each pixel, in which the gradation value and the number of ink ejections for each pixel are determined for the gradation data represented by m-bit information. By applying the represented index pattern, image data represented by n-bit information for each pixel is generated. This image data defines the number of ink ejections for each pixel on the recording medium. Details of this index processing will be described later.

  Next, in the mask process J0008, a plurality of image data is obtained by applying a plurality of mask patterns having 1-bit information for each pixel corresponding to a plurality of scans to image data represented by n-bit information. A plurality of print data items each represented by 1-bit information are generated by distributing the scans to one scan. By the plurality of print data, ink ejection or non-ejection for each pixel in each of a plurality of scans is determined. This mask process will be described later.

  Note that the index pattern and the mask pattern used in the index process J0007 and the mask process J0008 are stored in a predetermined memory of the printer 1000 in advance.

  The print data obtained by the mask data conversion process is supplied to the head drive circuit J0009 and the print head J0010. Based on the recording data, ink is ejected from the ejection ports 30 arranged in the recording head 7 to the recording medium 3.

(Index processing)
The index processing executed in this embodiment will be described in detail below. For the sake of simplicity, the gradation data is composed of 4-bit information (m = 4), so that nine gradation values (level 0 to level 8) are expressed, and each index is expanded. A case will be described in which image data composed of information of 2 bits per pixel (n = 2) is generated.

  FIG. 9 is a schematic diagram showing an index pattern applied in the present embodiment. 9A to 9I show index patterns corresponding to the case where the gradation values indicated by the gradation data are level 0 to level 8, respectively.

  The gradation data in this embodiment defines nine gradation values from level 0 to level 8 for each pixel group composed of four pixels. Here, when the gradation value indicated by the gradation data in a certain pixel group is level 0, as shown in FIG. 9A, image data corresponding to each of the four pixels constituting the pixel group is formed. An index pattern in which a value of “00” is assigned to all 2-bit information (hereinafter also referred to as pixel values) is applied. Here, when the pixel value is “00”, the ink is not ejected once to the corresponding pixel. Therefore, by using the index pattern shown in FIG. 9A, image data that does not eject ink once to all four pixels based on the gradation data whose gradation value is level 0 is obtained. Can be generated.

  Next, when the gradation value indicated by the gradation data in a certain pixel group is level 1, as shown in FIG. 9B, the pixel value in the upper left pixel is changed to a value other than the upper left pixel. An index pattern in which a value of “00” is assigned to the pixel values in the three pixels is applied. Here, when the pixel value is “01”, ink is ejected only once to the corresponding pixel. Therefore, by using the index pattern shown in FIG. 9B, ink is ejected once to one of the four pixels based on the gradation data whose gradation level is level 1, and the others. Image data that does not eject ink can be generated for the pixels.

  Thereafter, as the gradation value of the gradation data increases to levels 2, 3, and 4, as shown in FIGS. 9C to 9E, the corresponding index pattern is 1 for the pixel having the pixel value of “01”. It is set so that it increases one by one and the pixels having a pixel value of “00” decrease one by one. Therefore, by using the index patterns shown in FIGS. 9C to 9E, the gradation data having the gradation levels of 2 to 4 is once applied to 2 to 4 pixels among the 4 pixels. Image data that ejects ink one by one can be generated.

  Next, when the gradation value indicated by the gradation data in a certain pixel group is level 5, as shown in FIG. 9F, the pixel value in the upper left pixel is changed to a value other than the upper left pixel. An index pattern in which a value of “01” is assigned to the pixel values of the three pixels is applied. Here, when the pixel value is “10”, ink is ejected twice to the corresponding pixel. Therefore, by using the index pattern shown in FIG. 9 (f), ink is ejected twice from one gradation pixel from gradation data whose gradation level is level 5, and ink is ejected once to the other pixels. Image data to be ejected can be generated.

  Thereafter, as the gradation value of the gradation data rises to levels 6, 7, and 8, as shown in FIGS. 9G to 9I, the corresponding index pattern has 1 pixel having a pixel value of “10”. It is set so as to increase one by one and decrease one pixel having a pixel value of “01” one by one. Therefore, by using the index patterns shown in FIGS. 9 (g) to 9 (i), the gradation data having the gradation levels of 6 to 8 are used twice to 2 to 4 pixels out of 4 pixels. Image data that ejects ink one by one can be generated.

  As described above, in the present embodiment, image data is generated by applying the index pattern as described above to each pixel group including four pixels.

(Mask processing)
The mask processing executed in this embodiment will be described in detail below.

  FIG. 10 is a flowchart of a control program for executing mask processing in the present embodiment.

  First, in step S1, one pixel is selected as a target pixel to be subjected to mask processing from a plurality of pixels on the recording medium.

  Next, in step S2, it is determined whether the pixel value of the image data acquired by the index process corresponding to the selected pixel is “10”. Here, when it is determined that the pixel value is not “10”, that is, the pixel value is “01” or “00”, a first mask pattern group to be described later is selected for the pixel, and the corresponding pixel is selected. The image data to be masked is subjected to mask processing using the first mask pattern group selected in step S3, and print data for the pixel is generated. If it is determined that the pixel value is “10”, a second mask pattern group to be described later is selected for the pixel, and the image data corresponding to the pixel is the second mask selected in step S4. Mask processing is performed using the pattern group, and print data for the pixel is generated.

  After the mask process is executed in step S3 or step S4, it is determined in step S5 whether or not the mask process has been executed for all the pixels on the recording medium. If it is determined that there remains a pixel that has not been subjected to mask processing, the process returns to step S1 to select a target pixel on which mask processing is to be performed next. On the other hand, if it is determined that the mask process has been completed for all the pixels, it is determined that the generation of the recording data has been completed, and these processes are terminated.

  The mask pattern group applied in this embodiment will be described in detail below.

  FIG. 11 is a diagram schematically showing a first mask pattern group applied in the mask processing in the present embodiment. Here, FIGS. 11A to 11D correspond to the first to fourth scans, respectively, and show mask patterns each including 16 pixels of 4 pixels × 4 pixels. Further, as described above, each mask pattern is composed of 1-bit information for each pixel, and it is determined whether ink ejection is permitted or not permitted for each pixel. More specifically, in FIG. 11, a pixel to which a value of “1” is assigned is a print permission that allows ink ejection when the pixel value of image data corresponding to that pixel is “01” indicating ink ejection. This corresponds to a pixel (hereinafter also referred to as a first recording-allowed pixel). On the other hand, a pixel to which a value of “0” is assigned is a non-recording-permitted pixel (hereinafter referred to as a first pixel) that does not allow ink ejection even if the pixel value of the image data corresponding to that pixel is “01” indicating ink ejection. 1 is also referred to as a non-recordable pixel).

  In the four mask patterns (first mask pattern) constituting the first mask pattern group in the present embodiment, the first print permitting pixels are defined at mutually exclusive and complementary positions. In other words, in the four first mask patterns, the first print allowable pixels are determined so that the allowable number of ink ejections for each pixel is equal to one. More specifically, any one of the four mask patterns corresponds to the first print permission pixel in any one of the four mask patterns, and each of the other three mask patterns corresponds to the first non-print permission pixel. Yes.

  By applying such a first mask pattern, it is possible to generate print data that ejects ink at most once for each pixel. For example, the upper leftmost pixel of the 16 pixels corresponds to the first print permitting pixel in the first mask pattern corresponding to the first scan shown in FIG. When image data having a pixel value “01” indicating ink ejection is input to a pixel, ink is ejected to that pixel in the first scan. In addition, since the upper right pixel corresponds to the first print permitting pixel in the first mask pattern corresponding to the second scan shown in FIG. 11B, the upper right pixel indicates ink ejection. When image data having a pixel value of “01” is input, ink is ejected to the pixel in the second scan.

  The four first mask patterns shown in FIG. 11 have the same number of first print permitting pixels as each other. Therefore, for example, when image data having a pixel value “01” in all 16 pixels is input, print data having the same print rate in each of the four scans is generated.

  On the other hand, FIG. 12 is a diagram schematically showing a second mask pattern group applied in the mask processing in the present embodiment. Here, FIGS. 12A to 12D correspond to the first to fourth scans, respectively, and show mask patterns each including 16 pixels of 4 pixels × 4 pixels. Further, as described above, each mask pattern is composed of 1-bit information for each pixel, and it is determined whether ink ejection is permitted or not permitted for each pixel. More specifically, in FIG. 12, a pixel to which a value of “1” is assigned is a print permit that allows ink ejection when the pixel value of image data corresponding to that pixel is “10” indicating ink ejection. This corresponds to a pixel (hereinafter also referred to as a second recordable pixel). On the other hand, a pixel to which a value of “0” is assigned is a non-recording-permitted pixel (hereinafter referred to as a first pixel) that does not allow ink ejection even if the pixel value of image data corresponding to that pixel is “10” indicating ink ejection. 2) (also referred to as non-recordable pixels 2).

  In the four mask patterns (second mask pattern) constituting the second mask pattern group in this embodiment, the second print allowable pixels are set such that the allowable number of ink ejections for each pixel is equal to two. Is stipulated. Specifically, any of the pixels corresponds to the second print permission pixel in two mask patterns of the four mask patterns, and corresponds to the second non-print permission pixel in the other two mask patterns.

  From this, it can be seen that the number of second print permission pixels arranged in the second mask pattern group is larger than the number of first print permission pixels arranged in the first mask pattern group. . More specifically, the number of second print permission pixels arranged in the second mask pattern group is twice the number of first print permission pixels arranged in the first mask pattern group. Is set to

  By applying such a second mask pattern, it is possible to generate print data that ejects ink twice at a maximum for each pixel. For example, the upper leftmost pixel of the 16 pixels is the second mask pattern corresponding to the first scan shown in FIG. 12A and the second mask pattern corresponding to the fourth scan shown in FIG. This mask pattern corresponds to the second print permitting pixel, and therefore, when image data having a pixel value of “10” indicating ink ejection is input to the uppermost pixel, 1 is assigned to that pixel. Ink is ejected in the fourth scan. The upper right pixel is the second mask pattern in the second mask pattern corresponding to the second scan shown in FIG. 11B and the second mask pattern corresponding to the third scan shown in FIG. Since this corresponds to a print permitting pixel, when image data having a pixel value of “10” indicating ink ejection is input to the upper right pixel, ink is scanned for that pixel in the second and third scans. Will be discharged.

  Note that, in the four second mask patterns shown in FIG. 12, the same number of second print permitting pixels as each other is defined in the same manner as the first mask pattern. Therefore, for example, when image data having a pixel value of “10” is input in all 16 pixels, print data is generated such that the print rates in the four scans are substantially equal.

  As described above, in the present embodiment, the first and second mask pattern groups as described above are used, and the mask pattern group to be applied for each pixel is made different so as to be used for printing in a plurality of scans. Generate data.

  The process of generating print data using the index pattern shown in FIG. 9 and the first and second mask pattern groups shown in FIGS. explain.

  FIG. 13 is a schematic diagram for explaining a generation process of recording data in the present embodiment. Here, for the sake of simplicity, a case will be described in which an image corresponding to a unit region composed of pixel regions corresponding to 16 pixels X1 to X16 as shown in FIG. Here, the area on the data corresponding to the unit area shown in FIG. 13A includes a first pixel group composed of four pixels X1, X2, X5, and X6, and four pixels X9, X10, X13, and X14. 4 pixel groups including a second pixel group consisting of four pixels, a third pixel group consisting of four pixels X3, X4, X7, and X8, and a fourth pixel group consisting of four pixels X11, X12, X15, and X16 It is.

  FIG. 13B shows an example of input gradation data. The gradation data shown in FIG. 13B is level 1 in the first pixel group, level 3 in the second pixel group, level 5 in the third pixel group, and gradation level 7 in the fourth pixel group. Each has a gradation value.

  FIG. 13C is a diagram showing image data generated by applying the index pattern shown in FIG. 9 to the gradation data shown in FIG.

  First, the index pattern shown in FIG. 9B is used for the first pixel group whose gradation value is level 1, and the number of ink ejections for each pixel X1, X2, X5, and X6 is defined. . Specifically, since the index pattern shown in FIG. 9B determines ink ejection once for the upper left pixel of the four pixels and zero times for the other three pixels, A pixel value of “00” is assigned to “01” and the pixels X2, X5, and X6.

  Next, the index pattern shown in FIG. 9D is used for the second pixel group whose gradation value is level 3, and the number of ink ejections for each pixel X9, X10, X13, X14 is defined. The Specifically, since the index pattern shown in FIG. 9B determines ink ejection once for three pixels other than the upper right of the four pixels and zero times for the upper right pixel, the pixel X9, A pixel value of “01” is assigned to X13 and X14, and a pixel value of “00” is assigned to the pixel X10.

  Similarly, the index pattern shown in FIG. 9F is used for the third pixel group whose gradation value is level 5, and “01” is used for the pixels X4, X7, and X8, and A pixel value of “10” is assigned. Further, the index pattern shown in FIG. 9H is used for the fourth pixel group whose gradation value is level 7, and “01” is used for the pixel X12, and “10” is used for the pixels X11, X15, and X16. "Is assigned.

  Here, in the image data shown in FIG. 13C, the pixel value “10” is assigned to the pixels X3, X11, X15, and X16. Therefore, the mask processing is executed on the image data corresponding to the pixels X3, X11, X15, and X16 using the second mask pattern group shown in FIG. 12 in step S4 of FIG. On the other hand, a pixel value of “01” or “00” is assigned to the other pixels X1, X2, X4, X5, X6, X7, X8, X9, X10, X12, X13, X14, and X16. Therefore, the image data corresponding to the pixels X1, X2, X4, X5, X6, X7, X8, X9, X10, X12, X13, X14, X16 is the first mask pattern shown in FIG. 11 in step S3 of FIG. Mask processing is performed using the group.

  13 (d1) to (d4) are generated by applying the first and second mask pattern groups shown in FIGS. 11 and 12 to the image data shown in FIG. 13 (c), respectively. It is a figure which shows the recording data corresponding to the 4th scan.

  For example, as shown in FIG. 13C, a pixel value “01” is assigned to the image data corresponding to the pixel X1. Therefore, the first mask pattern group shown in FIG. 11 is applied to the image data corresponding to the pixel X1. Here, as can be seen from FIG. 11, in the first mask pattern corresponding to the first scan shown in FIG. 11A in the first mask pattern group, the pixel X1 has the first print permission pixel. It corresponds. Accordingly, as shown in FIG. 13 (d1), the recording data used in the first scanning is determined by ejecting ink to the pixel X1 (“1”).

  In the first mask pattern corresponding to the second, third, and fourth scans shown in FIGS. 11B, 11C, and 11D, the pixel X1 corresponds to the first non-recordable pixel. . Accordingly, as shown in FIGS. 13 (d2), (d3), and (d4), the print data used in the second, third, and fourth scans is determined by non-ejection of ink to the pixel X1 (“0”). )

  Also, as shown in FIG. 13C, the pixel value “10” is assigned to the image data corresponding to the pixel X3. Therefore, the second mask pattern group shown in FIG. 12 is applied to the image data corresponding to the pixel X3. Here, as can be seen from FIG. 12, in the second mask pattern group, the second mask pattern corresponding to the first and fourth scans shown in FIGS. Two recordable pixels correspond. Accordingly, as shown in FIGS. 13D1 and 13D4, the print data used in the first and fourth scans is the ink discharge determined for the pixel X3 (“1”).

  In the second mask pattern corresponding to the second and third scans shown in FIGS. 12B and 12C, the pixel X3 corresponds to the second non-recordable pixel. Accordingly, as shown in FIGS. 13D2 and 13D3, the print data used in the second and third scans is determined by non-ejection of ink for the pixel X3 (“0”).

  Recording data is generated by the same process for pixels other than the pixels X1 and X3.

  Here, with respect to the pixels X1, X2, X5, and X6 constituting the first pixel group, as can be seen from the recording data corresponding to the first pixel group shown in FIGS. 13 (d1) to (d4), the first time Ink is ejected to the pixel X1 by scanning. Therefore, the ink is ejected once in total for the first pixel group by four scans. Accordingly, it can be seen that ink is ejected the number of times corresponding to level 1 which is the gradation value of the gradation data shown in FIG.

  Further, the pixels X9, X10, X13, and X14 constituting the second pixel group have the first time as can be seen from the recording data corresponding to the second pixel group shown in FIGS. 13 (d1) to (d4). Ink is ejected to pixel X9 by scanning, pixel X13 by third scanning, and pixel X14 by fourth scanning. Therefore, ink is ejected three times in total for the second pixel group in four scans. Therefore, it can be seen that ink is ejected the number of times corresponding to level 3, which is the gradation value of the gradation data shown in FIG.

  Further, the pixels X3, X4, X7, and X8 constituting the third pixel group have the first time as can be seen from the recording data corresponding to the third pixel group shown in FIGS. 13 (d1) to (d4). Ink is ejected to pixel X3 by scanning, pixel X4 by second scanning, pixel X7 by third scanning, and pixels X3 and X8 by fourth scanning. Therefore, ink is ejected to the third pixel group five times in total by four scans. Therefore, it can be seen that ink is ejected the number of times corresponding to level 5 which is the gradation value of the gradation data shown in FIG.

  Further, the pixels X11, X12, X15, and X16 constituting the fourth pixel group have the first time as can be seen from the recording data corresponding to the fourth pixel group shown in FIGS. 13 (d1) to (d4). Ink is ejected to the pixels X11 and X16 in the scan, the pixels X12 and X15 in the second scan, the pixels X11 and X15 in the third scan, and the pixel X16 in the fourth scan. Therefore, ink is ejected to the fourth pixel group seven times in total by four scans. Therefore, it can be seen that ink is ejected the number of times corresponding to level 7 which is the gradation value of the gradation data shown in FIG.

  Thus, according to the present embodiment, it can be seen that the number of gradation values represented by the gradation data can be reproduced by the number of ink ejections.

  Furthermore, according to the present embodiment, it is possible to generate recording data capable of recording an image in which graininess and uniformity are hardly noticeable at each gradation value.

  FIG. 14 shows four print data corresponding to four scans generated by executing the index process and the mask process in the present embodiment from the gradation data having the gradation values of levels 0 to 8 in the present embodiment. Therefore, it is a figure which shows typically the frequency | count of ink discharge with respect to each pixel at the time of discharging ink.

  For example, in the case where print data is generated from gradation data whose gradation value is level 2 using the index pattern shown in FIG. 9 and the first and second mask pattern groups shown in FIGS. 11 and 12, FIG. As shown in c), ink is ejected once to pixel areas corresponding to the upper left pixel and the lower right pixel. As a result, it is possible to record an image with a graininess suppressed as compared to an image formed by recording data as shown in FIG.

  In the case where print data is generated from the gradation data having the gradation value of level 8 using the index pattern shown in FIG. 9 and the first and second mask pattern groups shown in FIGS. 11 and 12, FIG. As shown in i), ink is ejected twice to all the pixel regions corresponding to the four pixels. Thereby, it is possible to perform recording while suppressing a decrease in density and a decrease in uniformity as compared with an image formed by recording data as shown in FIG.

  As described above, according to the present embodiment, it is possible to perform recording with high graininess and less noticeable graininess.

(Second Embodiment)
In the first embodiment, a description has been given of a mode in which print data is generated by using an index pattern represented by n (n ≧ 2) bit information and applying different mask pattern groups according to pixel values for each pixel. .

  In contrast, in the present embodiment, a description will be given of a form in which recording data is generated using an index pattern represented by 1-bit information.

  Note that description of the same parts as those of the first and second embodiments described above will be omitted.

(Index processing)
The index processing executed in this embodiment will be described in detail below. As in the first embodiment, the gradation data is composed of 4-bit information (m = 4), so that gradation levels (level 0 to level 8) can be expressed. A case where key data is processed will be described.

  FIG. 15 is a schematic diagram showing an index pattern applied in the present embodiment. 9A to 9I show index patterns corresponding to the case where the gradation values indicated by the gradation data are level 0 to level 8, respectively.

  The index pattern applied in the present embodiment is such that gradation data corresponding to a pixel group composed of A (A ≧ 4) pixels is represented by B × A (B ≧ 2) pixels according to the gradation value. Each pixel is represented by 1-bit information that defines ink ejection (“1”) or non-ejection (“0”). Here, for simplicity, an index pattern in which A = 4 and B = 2 is shown.

  Each index pattern includes a first region ID1 corresponding to a pixel group composed of four first pixels and a second region ID2 corresponding to a pixel group composed of four second pixels. And have. Accordingly, by using the index pattern shown in FIG. 15 for a pixel group composed of four pixels, 2 pieces of image data defining ink ejection or non-ejection for the pixel group composed of four pixels are obtained. Will be generated.

  Here, when the gradation value indicated by the gradation data in a certain pixel group is level 0, as shown in FIG. 15A, each of the eight pixels in the first area ID1 and the second area ID2 is provided. An index pattern in which a value of “0” is assigned to all 1-bit information (hereinafter also referred to as pixel values) constituting the corresponding image data is applied. Here, when the pixel value is “0”, non-ejection of ink is determined for the corresponding pixel. Therefore, by using the index pattern shown in FIG. 15A, image data that does not eject ink once to all four pixels based on the gradation data whose gradation value is level 0 is obtained. Can be generated.

  Next, when the gradation value indicated by the gradation data in a certain pixel group is level 1, as shown in FIG. 15B, the pixel value of the upper left pixel in the first area ID1 is “1”. An index pattern in which a value of “0” is assigned to the pixel values of three pixels other than the upper left pixel in the first area ID1 and all the pixels in the second area ID2 is applied. Here, when the pixel value is “1”, non-ejection of ink is determined for the corresponding pixel. Therefore, by using the index pattern shown in FIG. 15B, one time is applied to one first pixel of four first pixels based on the gradation data whose gradation level is level 1. It is possible to generate image data that ejects ink one by one and does not eject ink to the other first pixels and all the second pixels.

  Thereafter, as the gradation value of the gradation data increases to levels 2, 3, and 4, as shown in FIGS. 15C to 15E, the first area ID1 in the corresponding index pattern is “1”. The pixels having the pixel value of 1 are increased one by one, and the pixels having the pixel value of “0” are decreased one by one. Also, a pixel value of “0” is assigned to all the pixels in the second area ID2 in the corresponding index pattern. Therefore, by using the index patterns shown in FIGS. 15C to 15E, the gradation data having the gradation levels of 2 to 4 are converted into 2 to 4 pixels of the 4 first pixels, respectively. Image data is generated so that ink is ejected once every four pixels and ink is not ejected to the four second pixels.

  Next, when the gradation value indicated by the gradation data in a certain pixel group is level 5, as shown in FIG. 15 (f), all the pixels in the first area ID1 and the second area ID2 An index pattern in which a value “1” is assigned to the pixel value in the upper left pixel and a value “0” is assigned to the pixel values in the three pixels other than the upper left pixel in the second region ID2 is applied. Therefore, by using the index pattern shown in FIG. 15 (f), one second pixel out of the four first pixels and the four second pixels from the gradation data whose gradation level is level 5. In contrast, it is possible to generate image data such that ink is ejected once and ink is not ejected to the other second pixels.

  Thereafter, as the gradation value of the gradation data rises to levels 6, 7, and 8, as shown in FIGS. 15G to 15I, the second area ID2 in the corresponding index pattern is “1”. The pixels having the pixel value of 1 are increased one by one, and the pixels having the pixel value of “0” are decreased one by one. Also, a pixel value of “1” is assigned to all the pixels in the first area ID1 in the corresponding index pattern. Therefore, by using the index patterns shown in FIGS. 15G to 15I, the gradation data having the gradation levels of 2 to 4 are converted into 2 to 4 pixels of the 4 second pixels, respectively. Image data is generated such that ink is ejected once every two pixels and ink is ejected to the four first pixels.

  As described above, in this embodiment, the gradation value of level 4 is used as a threshold value, and when the gradation value is equal to or less than the threshold value, the pixel value “1” is not assigned to the second area ID2 of the index pattern. If it is higher, a pixel value of “1” is assigned to the second area ID2 of the index pattern.

  As described above, in the present embodiment, four pixels are obtained by applying the index pattern having the first region ID1 and the second region ID2 as described above to each pixel group including four pixels. Two types of image data for determining whether ink is ejected or not are generated.

(Mask processing)
The mask processing executed in this embodiment will be described in detail below.

  FIG. 16 is a flowchart of a control program for executing mask processing in the present embodiment.

  First, in step S11, it is determined whether or not the image data acquired by the index processing from which mask processing is performed is image data generated by the first area ID1 of the index pattern shown in FIG. If it is determined that the image data is the image data generated in the first area ID1 of the index pattern, the image data is subjected to mask processing using a first mask pattern group described later in step S12, and the first data ID1 recording data corresponding to the area ID1 is generated. If it is determined that the image data is not image data generated in the first area ID1 of the index pattern, that is, image data generated in the second area ID2, the image data is described later in step S13. The mask processing is performed using the second mask pattern group to generate ID2 recording data corresponding to the second area ID2.

  After the mask process is executed in step S12 or step S13, the ID1 record data and ID2 record data are combined in step S14. Specifically, print data used in each scan is generated by calculating a logical sum of print data for ID1 and print data for ID2. That is, when one of the ID1 recording data and the ID2 recording data is determined to eject ink (“1”) and the other is not ejected ink (“0”) in a certain pixel, On the other hand, print data for determining ink ejection (“1”) is generated. Further, when ink ejection (“1”) is determined by both the ID1 recording data and the ID2 recording data in a certain pixel, the recording data for determining the ink ejection (“1”) for the pixel is stored. Generate. Further, when non-ejection (“0”) of ink is determined in both of the ID1 recording data and the ID2 recording data in a certain pixel, the recording that determines non-ejection (“0”) of the ink for the pixel is performed. Generate data.

  The mask pattern group applied in this embodiment will be described in detail below.

  In the present embodiment, mask processing is performed using B mask pattern groups. As described above, here, in order to describe the case where B = 2, two mask pattern groups of the first mask pattern group and the second mask pattern group are used.

  In the present embodiment, as in the first embodiment, four first mask patterns shown in FIGS. 11A to 11D are applied as the first mask pattern group. Here, in the present embodiment, the pixel assigned the value “1” in the first mask pattern shown in FIG. 11 has the pixel value of the image data corresponding to the pixel “1” indicating ink ejection. This corresponds to a print permitting pixel that allows ink ejection in some cases. On the other hand, a pixel to which a value of “0” is assigned corresponds to a non-printable pixel that does not allow ink ejection even if the pixel value of image data corresponding to that pixel is “1” indicating ink ejection. ing.

  FIG. 17 is a diagram schematically showing a second mask pattern group applied in the mask processing in the present embodiment. Here, FIGS. 17A to 17D correspond to the first to fourth scans, respectively, and show mask patterns each including 16 pixels of 4 pixels × 4 pixels.

  Here, the four second mass patterns constituting the second mask pattern group shown in FIG. 17 are the four first mass patterns constituting the first mask pattern group shown in FIG. 11 described in the first embodiment. As in the mask pattern, the print allowable pixels are determined so that the allowable number of ink ejections for each pixel is equal to 1. More specifically, any one of the four mask patterns corresponds to a print permitting pixel, and the other three mask patterns correspond to non-print permitting pixels. Therefore, it can be seen that the number of print permitting pixels arranged in the second mask pattern group is the same as the number of print permitting pixels arranged in the first mask pattern group.

  By applying such first and second mask pattern groups, it is possible to generate print data that ejects ink twice at a maximum for each pixel.

  Also, the four second mask patterns shown in FIG. 17 have the same number of print-allowable pixels as each other, like the first mask pattern shown in FIG. Therefore, for example, when image data having a pixel value “1” in all 16 pixels is input, print data is generated so that the print rates in the four scans are substantially equal.

  Further, in the four second mask patterns shown in FIG. 17, the print permitting pixels are determined at positions mutually exclusive with the mask pattern corresponding to the same scan among the four first mask patterns shown in FIG. Yes. Therefore, in the first mask pattern corresponding to the first scan shown in FIG. 11A, the pixel corresponding to the print-allowed pixel is the second mask pattern corresponding to the first scan shown in FIG. Is a non-recordable pixel. Similarly, in the second mask pattern corresponding to the first scan shown in FIG. 17A, the pixel corresponding to the print permitting pixel is the first mask corresponding to the first scan shown in FIG. The pattern is a non-recordable pixel. The same relationship applies to other mask patterns corresponding to the second to fourth scans. As a result, even when ink ejection is determined for the same pixel in the image data for ID1 and the image data for ID2, the image data for ID1 and the image data for ID2 can be distributed to different scans. Therefore, it is possible to generate print data that satisfies the condition that ink is ejected only once for the same pixel area in the same scan.

  As described above, in the present embodiment, the first mask pattern group shown in FIG. 11 is applied to the image data for ID1, and the second mask pattern group shown in FIG. 17 is applied to the image data for ID2. ID1 recording data and ID2 recording data are generated.

  The process of generating print data using the index pattern shown in FIG. 15 and the first and second mask pattern groups shown in FIGS. explain.

  FIG. 18 is a schematic diagram for explaining a recording data generation process in the present embodiment. As can be seen from FIGS. 18A and 18B, the case where the same data as the gradation data shown in FIGS. 13A and 13B is processed is described here.

  FIG. 18C1 is a diagram showing ID1 image data generated by applying the first area ID1 of the index pattern shown in FIG. 15 to the gradation data shown in FIG. 18B. FIG. 18C2 is a diagram showing ID2 image data generated by applying the second area ID2 of the index pattern shown in FIG. 15 to the gradation data shown in FIG. 18B.

  First, the index pattern shown in FIG. 15B is used for the first pixel group composed of the pixels X1, X2, X5, and X6 whose gradation value is level 1, and each pixel X1, X2, Ink ejection or non-ejection for X5 and X6 is defined. Specifically, the first area ID1 of the index pattern shown in FIG. 15B defines ink ejection to the upper left pixel of the four pixels and ink non-ejection to the other three pixels. Therefore, as shown in FIG. 18C1, ID1 image data in which “1” is assigned to the pixel X1 and “0” is assigned to the pixels X2, X5, and X6 is generated. In addition, since the second area ID2 of the index pattern shown in FIG. 15B determines non-ejection of ink to all four pixels, as shown in FIG. 18C2, the pixels X1, X2, X5 , Image data for ID2 in which a pixel value of “0” is assigned to all of X6 is generated.

  Next, the index pattern shown in FIG. 15D is used for the second pixel group including the pixels X9, X10, X13, and X14 whose gradation value is level 3, and each pixel X9, X10 is used. , X13, and X14 are defined as ink ejection or non-ejection. Specifically, the first area ID1 of the index pattern shown in FIG. 15D determines ink ejection to three pixels other than the upper right among the four pixels and non-ejection of ink to the upper right pixel. Therefore, as shown in FIG. 18C1, ID1 image data in which pixel values “1” are assigned to the pixels X9, X13, and X14 and “0” is assigned to the pixel X10 is generated. Further, since the second area ID2 of the index pattern shown in FIG. 15 (d) determines non-ejection of ink to all four pixels, pixels X9, X10, X13 as shown in FIG. 18 (c2). , X2 is generated with ID2 image data in which a pixel value of “0” is assigned.

  Similarly, the index pattern shown in FIG. 15F is used for the third pixel group including the pixels X3, X4, X7, and X8 whose gradation value is level 5. Accordingly, as shown in FIG. 18C1, ID1 image data in which the pixel value “1” is assigned to all of the pixels X3, X4, X7, and X8 is generated. In addition, as shown in FIG. 18C2, ID2 image data in which “1” is assigned to the pixel X3 and “0” is assigned to the pixels X4, X7, and X8 is generated.

  Furthermore, the index pattern shown in FIG. 15H is used for the fourth pixel group composed of the pixels X11, X12, X15, and X16 whose gradation value is level 7. Accordingly, as shown in FIG. 18 (c1), ID1 image data in which the pixel value “1” is assigned to all of X11, X12, X15, and X16 is generated. Further, as shown in FIG. 18C2, ID2 image data in which “1” is assigned to the pixels X11, X15, and X16 and “0” is assigned to the pixel X12 is generated.

  FIGS. 18D1 to 18D4 respectively show the first to fourth scans generated by applying the first mask pattern group shown in FIG. 11 to the ID1 image data shown in FIG. 18C1. It is a figure which shows the recording data for ID1 corresponding to.

  For example, as shown in FIG. 18C1, a pixel value “1” is assigned to the image data for ID1 corresponding to the pixel X1. Here, as can be seen from FIG. 11, in the first mask pattern corresponding to the first scan shown in FIG. 11A in the first mask pattern group, the record allowable pixel corresponds to the pixel X1. . Accordingly, as shown in FIG. 18 (d1), the ID1 recording data corresponding to the first scan is data (“1”) that determines the ejection of ink to the pixel X1.

  Further, in the first mask pattern corresponding to the second, third, and fourth scans shown in FIGS. 11B, 11C, and 11D, a non-printable pixel corresponds to the pixel X1. Accordingly, as shown in FIGS. 18 (d2), (d3), and (d4), the ID1 print data corresponding to the second, third, and fourth scans is determined by determining that ink is not ejected from the pixel X1 ( “0”).

  Similar processing is performed for pixels other than the pixel X1, and ID1 recording data shown in FIGS. 18D1 to 18D4 is generated.

  FIGS. 18E1 to 18E4 respectively show the first to fourth scans generated by applying the second mask pattern group shown in FIG. 17 to the image data for ID2 shown in FIG. 18C2. It is a figure which shows the recording data for ID2 corresponding to.

  For example, as shown in FIG. 18C2, a pixel value “1” is assigned to the image data for ID2 corresponding to the pixel X11. Here, as can be seen from FIG. 17, in the second mask pattern corresponding to the fourth scan shown in FIG. 17 (d) in the second mask pattern group, the record allowable pixel corresponds to the pixel X11. . Accordingly, as shown in FIG. 18 (e4), the ID2 recording data corresponding to the fourth scan is determined by determining the ink ejection to the pixel X11 ("1").

  In the second mask pattern corresponding to the first, second, and third scans shown in FIGS. 17A, 17B, and 17C, the pixel X11 corresponds to a non-printable pixel. Accordingly, as shown in FIGS. 18 (e1), (e2), and (e3), the ID2 print data corresponding to the first, second, and third scans is defined as non-ejection of ink to the pixel X11 ( “0”).

  Similar processing is performed on the pixels other than the pixel X11, and ID2 recording data shown in FIGS. 18 (e1) to (e4) is generated.

  18 (f1) to (f4) are generated by combining the ID1 recording data shown in FIGS. 18 (d1) to (d2) and the ID2 recording data shown in FIGS. 18 (e1) to (e2) for each scan. It is a figure which shows the recording data used by each of the 1st-4th scanning performed.

  The print data used in the first scan shown in FIG. 18 is the logical sum of the ID1 image data and the ID2 image data corresponding to the first scan shown in FIGS. 18 (d1) and 18 (e1). Is generated. More specifically, in the image data for ID1, ink ejection is determined by the pixels X1, X3, X9, and X11, and in the image data for ID2, ink ejection is determined by the pixel X16. As shown in (f1), print data in which ink ejection is determined for the pixels X1, X3, X9, X11, and X16 is generated.

  Similarly, print data corresponding to the second to fourth scans is generated. As a result, print data in which ink ejection is determined for the pixels X4, X12, and X15 as shown in FIG. 18F2 is generated as print data corresponding to the second scan. Also, print data in which ink ejection is determined at the pixels X7, X13, and X15 as shown in FIG. 18 (f3) is generated as print data corresponding to the third scan. In addition, as print data corresponding to the fourth scan, print data in which ink ejection is determined for the pixels X3, X8, X11, X14, and X16 as shown in FIG. 18 (f4) is generated.

  Here, with respect to the pixels X1, X2, X5, and X6 constituting the first pixel group, as can be seen from the recording data corresponding to the first pixel group shown in FIGS. 18 (f1) to (f4), the first time Ink is ejected to the pixel X1 by scanning. Therefore, the ink is ejected once in total for the first pixel group by four scans. Therefore, it can be seen that ink is ejected the number of times corresponding to level 1 which is the gradation value of the gradation data shown in FIG.

  Further, the pixels X9, X10, X13, and X14 constituting the second pixel group have the first time as can be seen from the recording data corresponding to the second pixel group shown in FIGS. 18 (f1) to (f4). Ink is ejected to pixel X9 by scanning, pixel X13 by third scanning, and pixel X14 by fourth scanning. Therefore, ink is ejected three times in total for the second pixel group in four scans. Therefore, it can be seen that ink is ejected the number of times corresponding to level 3, which is the gradation value of the gradation data shown in FIG.

  Further, the pixels X3, X4, X7, and X8 constituting the third pixel group have the first time as can be seen from the recording data corresponding to the third pixel group shown in FIGS. 18 (f1) to (f4). Ink is ejected to pixel X3 by scanning, pixel X4 by second scanning, pixel X7 by third scanning, and pixels X3 and X8 by fourth scanning. Therefore, ink is ejected to the third pixel group five times in total by four scans. Therefore, it can be seen that ink is ejected the number of times corresponding to level 5, which is the gradation value of the gradation data shown in FIG.

  Further, the pixels X11, X12, X15, and X16 constituting the fourth pixel group have the first time as can be seen from the recording data corresponding to the fourth pixel group shown in FIGS. 18 (f1) to (f4). Ink is ejected to the pixels X11 and X16 in the scan, the pixels X12 and X15 in the second scan, the pixel X15 in the third scan, and the pixels X11 and X16 in the fourth scan. Therefore, ink is ejected to the fourth pixel group seven times in total by four scans. Therefore, it can be seen that ink is ejected the number of times corresponding to level 7, which is the gradation value of the gradation data shown in FIG.

  As described above, according to this embodiment, it is understood that the number of gradation values represented by the gradation data can be reproduced by the number of ink ejections as in the first embodiment.

  Also in the present embodiment, as in the first embodiment, the ink is ejected in accordance with the recording data generated based on the gradation data having the gradation values of levels 0 to 8, so that FIG. The number of ink ejections for each pixel as shown can be reproduced. As a result, according to the present embodiment, it is possible to generate print data that can record an image with high granularity, in which graininess is not noticeable in each gradation value.

(Third embodiment)
In the first and second embodiments, a mode is described in which recording is performed by a plurality of recording scans on a unit area on a recording medium.

  In contrast, in the present embodiment, a plurality of recording heads corresponding to each ink having a length corresponding to the entire width direction (Z direction) of the recording medium are used, and relative recording between the recording head and the recording medium is performed. A mode in which recording is performed by performing scanning once will be described.

  The description of the same parts as those in the first and second embodiments described above will be omitted.

  FIG. 19 is a side view partially showing an internal configuration of the image recording apparatus according to the present embodiment.

  The four recording heads 601 to 604 each include yellow (Y), magenta (M), light magenta (Lm), cyan (C), light cyan (Lc), and black for each recording head (discharge port array). A predetermined number of ejection openings (not shown) for ejecting each ink of (Bk) are arranged in the Z direction. Therefore, a total of four ejection port arrays that eject one color ink are arranged in the recording heads 601 to 604. The length of the ejection port array in the Z direction is equal to or longer than the length of the recording medium 3 in the Z direction so that recording can be performed on the entire area of the recording medium 3 in the Z direction. These recording heads 601 to 612 are arranged side by side in the W direction intersecting with the Z direction. The four recording heads 601 to 604 are collectively referred to as a recording unit.

  The conveying belt 400 is a belt for conveying the recording medium 3, and conveys the recording medium 3 from the feeding unit 401 to the discharging unit 402 in the W direction intersecting with the Z direction as the conveying belt 400 rotates.

  In this image recording apparatus, since an image can be completed by one recording scan, it is possible to reduce the recording time.

  In the present embodiment, mask patterns corresponding to the respective scans used in the first and second embodiments are applied to the four ejection port arrays that eject the same color ink in the recording heads 601 to 604 shown in FIG. Use to distribute image data. For example, when the first mask pattern group shown in FIG. 11 is used, image data is distributed to the recording head 601 by applying the mask pattern shown in FIG. Similarly, the mask data shown in FIGS. 11B, 11C, and 11D is applied to the recording heads 602, 603, and 604, respectively, to distribute image data. As a result, according to the present embodiment, even when a plurality of recording heads are used, it is possible to generate recording data that is less noticeable in graininess and can record an image with high uniformity.

  In addition, the length in the Z direction of the ejection port array used in the present embodiment is a length corresponding to the width of the recording medium, but the length can be increased by arranging a plurality of shorter ejection port arrays in the Z direction. It is also possible to use a so-called connecting head as a recording head.

  In each of the embodiments, a so-called thermal jet type ink jet recording apparatus and a recording method for ejecting ink by foaming energy generated by heating have been described. However, the present invention is not limited to the thermal jet type ink jet recording apparatus. For example, the present invention can be effectively applied to various image recording apparatuses such as a so-called piezo-type ink jet recording apparatus that discharges ink using a piezoelectric element.

  In each embodiment, the image processing method using the image recording apparatus is described. However, the image processing apparatus that generates data for performing the image processing method described in each embodiment is separated from the image recording apparatus. It can also be applied to the prepared form. Further, the present invention can also be applied to a storage medium such as a CD-ROM that stores a program for generating data for performing the image processing method described in each embodiment. Furthermore, it goes without saying that the program can be widely applied to a mode in which the program is provided in a part of the image recording apparatus.

  The “recording medium” includes not only paper used in general recording apparatuses but also a wide range of cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. .

  Further, “ink” should be interpreted broadly as in the definition of “recording”. In other words, the “ink” used in the present embodiment is applied onto a recording medium, thereby forming an image, a pattern, a pattern, or the like, processing of the recording medium, or ink processing (for example, ink applied to the recording medium). A liquid that can be subjected to solidification or insolubilization of the colorant therein.

3 Recording medium 7 Recording head 301 CPU
302 ROM

Claims (24)

Ink ejection or non-ejection is determined for each of the pixel areas corresponding to a plurality of pixels in the unit area in each of a plurality of relative scans of the unit area on the recording medium of the recording head for ejecting ink. An image processing apparatus for generating print data represented by 1-bit information for each pixel used in each of the plurality of scans,
First acquisition means for acquiring, for each pixel, image data represented by n (n ≧ 2) bit information relating to the number of ink ejections to at least each of the plurality of pixel regions;
In each of the plurality of mask pattern groups including at least the first and second mask pattern groups, each of which is defined as permissible or non-permissible for ejecting ink to each pixel and represented by 1-bit information for each pixel. Selection means for selecting two mask pattern groups;
The recording data used in each of the plurality of scans for each pixel based on the image data acquired by the first acquisition unit and one mask pattern group selected for each pixel by the selection unit. First generating means for generating
The number of pixels for which ink discharge permission is determined in the second mask pattern group is greater than the number of pixels for which ink discharge permission is determined in the first mask pattern group,
(I) the first mask pattern group in a pixel in which the number of ink ejections indicated by n-bit information representing the image data acquired by the first acquisition unit is the first number; (Ii) In a pixel in which the number of ink ejections indicated by the n-bit information representing the image data acquired by the first acquisition unit is a second number greater than the first number An image processing apparatus, wherein the second mask pattern group is selected. n = 2,
The image processing apparatus according to claim 1, wherein the number of ink ejections indicated by the 2-bit information representing the image data is a maximum of two times. The first mask pattern group includes a plurality of first mask patterns corresponding to the plurality of scans,
The image processing apparatus according to claim 2, wherein the plurality of first mask patterns are set to allow ink ejection once for each pixel in total.   Each of the plurality of first mask patterns is set to allow or disallow ink ejection to each pixel so that the allowable number of ink ejections to each pixel is substantially the same. The image processing apparatus according to claim 3. The second mask pattern group includes a plurality of second mask patterns corresponding to the plurality of scans,
5. The image processing according to claim 2, wherein the plurality of second mask patterns are set to permit ink ejection twice in total for each pixel. 6. apparatus.   Each of the plurality of second mask patterns is configured to allow or disallow ink ejection to each pixel so that the allowable number of ink ejections to each pixel is substantially the same. The image processing apparatus according to claim 5. Second acquisition means for acquiring gradation data represented by m (m> n) -bit information related to the gradation value of the image in each of the pixel group composed of the plurality of pixels based on the image data When,
Each pixel in which the number of ink ejections for each of a plurality of pixels constituting the pixel group is determined according to the gradation data in each pixel group acquired by the second acquisition unit and the gradation value in each pixel group 7. The apparatus according to claim 1, further comprising: a second generation unit configured to generate the image data based on an index pattern represented by n-bit information per hit. Image processing apparatus.   The index pattern is defined so that when the gradation value in a certain pixel group is the first gradation value, the ink is ejected to the pixels constituting the pixel group by the first number of times. The image processing apparatus according to claim 7.   When the gradation value in a certain pixel group is a second gradation value that is one gradation higher than the first gradation value, the index pattern is one pixel in each pixel constituting the pixel group. The ink is ejected by the second number of times, and the ink is ejected by the first number of times to pixels other than the one pixel. An image processing apparatus according to 1. m = 4,
The image processing apparatus according to claim 7, wherein the gradation data represents at least nine gradation values. Ink ejection or non-ejection is determined for each of the pixel areas corresponding to a plurality of pixels in the unit area in each of a plurality of relative scans of the unit area on the recording medium of the recording head for ejecting ink. An image processing apparatus for generating print data represented by 1-bit information for each pixel used in each of the plurality of scans,
First acquisition means for acquiring gradation data represented by m (m ≧ 3) bits of information relating to the gradation value of an image in each of a pixel group composed of A (A ≧ 4) pixels; ,
For each of the B × A (B ≧ 2) pixels corresponding to the pixel group in accordance with the gradation data in each pixel group acquired by the first acquisition unit and the gradation value in each pixel group. Each pixel that defines ink ejection or non-ejection for each B × A pixel for each pixel group based on an index pattern represented by 1-bit information for each pixel that defines ink ejection or non-ejection First generation means for generating image data represented by 1-bit information per hit,
Ink mask ejection or non-permission for each pixel is defined, and B mask pattern groups represented by 1-bit information for each pixel, and the number of pixels for which ejection of ink is determined is substantially equal to each other Based on the B mask pattern groups and the image data generated by the first generation means, each of the plurality of scans corresponding to each of the A pixels constituting each pixel group. An image processing apparatus comprising: a second generation unit configured to generate the recording data used in the process. The B mask pattern groups include a first mask pattern group including a plurality of first mask patterns corresponding to the plurality of scans,
12. The plurality of first mask patterns constituting the first mask pattern group are set to permit ink ejection once for each pixel in total. Image processing apparatus.   Each of the plurality of first mask patterns constituting the first mask pattern group is allowed or not allowed to discharge ink to each pixel so that the allowable number of ink discharges is substantially the same. The image processing apparatus according to claim 12, wherein the image processing apparatus is defined. The B mask pattern groups correspond to the plurality of scans, and are formed of a plurality of second mask patterns different from the plurality of first mask patterns constituting the first mask pattern group. 2 mask pattern groups,
A pixel for which ink ejection permission is determined in the second mask pattern corresponding to a predetermined scan among the plurality of second mask patterns is the predetermined one of the plurality of first mask patterns. 14. The image processing apparatus according to claim 12, wherein non-permission of ink ejection is defined in the first mask pattern corresponding to scanning.   Among the plurality of first mask patterns, the pixels of the first mask pattern corresponding to the predetermined scanning that are determined to be allowed to eject ink include the pixels of the plurality of second mask patterns. The image processing apparatus according to claim 14, wherein non-permission of ink ejection is defined in the second mask pattern corresponding to a predetermined scan.   The plurality of mask patterns constituting each of the B mask pattern groups are allowed to discharge ink once in total for each pixel in any of the B mask pattern groups. The image processing apparatus according to claim 11, wherein the image processing apparatus is an image processing apparatus.   In each of the plurality of mask patterns constituting each of the B mask pattern groups, the allowable number of ink ejections for each pixel is substantially the same in each of the B mask pattern groups. The image processing apparatus according to claim 11, wherein permission or non-permission of ink ejection for each pixel is defined. A = 4, B = 2,
The index pattern ejects ink only to A first pixels of the B × A pixels corresponding to the pixel group when a gradation value in a pixel group is equal to or less than a predetermined threshold value. The image processing apparatus according to claim 11, wherein the image processing apparatus is defined as follows.   When the gradation value in a certain pixel group is higher than the predetermined threshold value, the index pattern inks all of the A first pixels of the B × A pixels corresponding to the pixel group. 19. The image processing according to claim 18, wherein the image processing is defined such that ink is ejected to any one of the A second pixels other than the A first pixels. apparatus.   The second generation unit includes a plurality of first mask patterns corresponding to the plurality of scans of the B mask pattern groups for the image data corresponding to the A first pixels. A first mask pattern group composed of: B and corresponding to the plurality of scans of the B mask pattern groups for the image data corresponding to the A second pixels 20. A second mask pattern group constituted by a plurality of second mask patterns different from the plurality of first mask patterns constituting the first mask pattern group is applied. An image processing apparatus according to 1. l = 4,
21. The image processing apparatus according to claim 11, wherein the gradation data represents at least nine gradation values.   The image processing apparatus according to claim 1, further comprising the recording head. Ink ejection or non-ejection is determined for each of the pixel areas corresponding to a plurality of pixels in the unit area in each of a plurality of relative scans of the unit area on the recording medium of the recording head for ejecting ink. An image processing method for generating print data represented by 1-bit information for each pixel used in each of the plurality of scans,
A first acquisition step of acquiring image data represented by information of n (n ≧ 2) bits related to the number of ink ejections for at least each of the plurality of pixel regions for each pixel;
In each of the plurality of mask pattern groups including at least the first and second mask pattern groups, each of which is defined as permissible or non-permissible for ejecting ink to each pixel and represented by 1-bit information for each pixel. A selection process for selecting two mask pattern groups;
The recording data used in each of the plurality of scans for each pixel based on the image data acquired in the first acquisition step and one mask pattern group selected for each pixel in the selection step. A first generating step for generating
The number of pixels for which ink discharge permission is determined in the second mask pattern group is greater than the number of pixels for which ink discharge permission is determined in the first mask pattern group,
In the selection step, (i) the first mask pattern group in the pixel in which the number of ink ejections indicated by the n-bit information representing the image data acquired in the first acquisition step is the first number. (Ii) In a pixel in which the number of ink ejections indicated by the n-bit information representing the image data acquired in the first acquisition step is a second number greater than the first number An image processing method, wherein the second mask pattern group is selected. Ink ejection or non-ejection is determined for each of the pixel areas corresponding to a plurality of pixels in the unit area in each of a plurality of relative scans of the unit area on the recording medium of the recording head for ejecting ink. An image processing method for generating print data represented by 1-bit information for each pixel used in each of the plurality of scans,
A first acquisition step of acquiring gradation data represented by m (m ≧ 3) bits of information relating to the gradation value of an image in each of the pixel groups composed of A (A ≧ 4) pixels; ,
For each of the B × A (B ≧ 2) pixels corresponding to the pixel group according to the gradation data in each pixel group acquired by the first acquisition step and the gradation value in each pixel group Each pixel that defines ink ejection or non-ejection for each B × A pixel for each pixel group based on an index pattern represented by 1-bit information for each pixel that defines ink ejection or non-ejection A first generation step of generating image data represented by 1 bit per hit,
Ink mask ejection or non-permission for each pixel is defined, and B mask pattern groups represented by 1-bit information for each pixel, and the number of pixels for which ejection of ink is determined is substantially equal to each other Based on the B mask pattern groups and the image data generated by the first generation process, each of the plurality of scans corresponding to each of the A pixels constituting each pixel group. And a second generation step for generating the recording data used in the image processing method.

Images