JP4310944B2 - Print control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for printing an image on a print medium by discharging ink.
[0002]
[Prior art]
2. Description of the Related Art In recent years, inkjet printers that eject several colors of ink from an ink head have become widespread as computer output devices, and are widely used for printing images processed by a computer in multiple colors and multiple gradations.
[0003]
When line drawings such as characters and illustrations are printed with an inkjet printer, the outline of the line drawing may be blurred. Such blurring of the outline portion is suitable for a natural image such as a photograph with respect to an outflow of ink from an ink reservoir generated because the ink ejected to the line drawing area cannot be completely absorbed by the print medium, or an image representing the line drawing. This is because halftone processing is performed.
[0004]
[Problems to be solved by the invention]
In order to suppress such blurring, a method of reducing the ink amount of dots forming the outline portion of the line drawing is also conceivable. However, when such a method is applied to an image in which a natural image such as a photograph and an artificial line drawing are mixed, the ink amount in the area representing the natural image is reduced, so that the image quality of the natural image is deteriorated. There was a fear. In addition, when printing an image that contains both natural and line drawings, it is difficult to perform halftone processing that achieves both natural image quality and line drawing image quality. It was.
[0005]
The present invention has been made to solve the above-described problems in the prior art, and in an image in which an area representing a natural image and an area representing a line drawing are mixed, the image quality of the line drawing is not excessively deteriorated. The object is to suppress blurring that occurs in the contour portion.
[0006]
[Means for solving the problems and their functions and effects]
In order to solve at least a part of the above-described problems, the first aspect of the present invention provides a printing apparatus for performing printing using a printing unit that forms dots on a print medium while performing main scanning of a print head. A print control device that generates print data to be supplied to a section, and that represents a dot formation state of each pixel in a print image according to multi-tone image data representing the color of each pixel of the image to be printed A dot data generation unit that generates data, and determines whether the color of each pixel is black according to the image data, and black indicating a black region where the color of the pixel is black according to the determination A black determination unit that generates region extraction data, and a specific contour portion that is at least a part of a pixel that forms a contour of the black region out of pixels belonging to the black region according to the black region extraction data Outline extraction unit to extract Characterized by comprising an ink amount reducer to adjust the dot data so as to reduce the amount of ink dots formed by the black ink in the particular contour.
[0007]
According to the first aspect of the present invention, the print data is adjusted so as to reduce the ink amount of the black dots in the outline of the black region, so that the outline portion of the line drawing can be obtained without excessively degrading the image quality of the natural image. It is possible to suppress blurring due to ink bleeding that occurs in step S2.
[0008]
In the print control apparatus, the black determination unit generates natural image region extraction data that is data in which the color of a pixel belonging to the black region in the image data is replaced with a color other than black. The dot data generation unit generates black region black dot data representing a dot formation state in which each pixel belonging to the black region is filled with black dots according to the black region extraction data. A natural image area black dot data generation unit that generates a natural image area black dot data representing a black dot formation state in each pixel by performing a halftone process on the natural image area extraction data, and the natural image area By combining the black dot data and the black area black dot data, It is preferable to include a dot data synthesis unit that generates dot data representing the formation state of the dots.
[0009]
In this way, for black areas representing line drawings, dot data representing the dot formation state in which each pixel is filled with black dots is generated, and for natural image areas representing natural images, halftones are added to the natural image area extraction data. Since the dot data representing the dot formation state is generated by performing the processing, it is possible to suppress not only blurring caused by ink bleeding but also blurring of the outline portion of the line drawing occurring in the halftone processing.
[0010]
In the above-described printing control apparatus, the printing unit includes a plurality of nozzles and a plurality of ejection driving elements for ejecting ink droplets from the plurality of nozzles, respectively, and one pixel on the print medium using each nozzle. A print head capable of selectively forming any one of N types of dots of different sizes (N is an integer of 2 or more), and the ink amount reducing unit includes the N type of dots of the N types of dots. It is preferable to reduce the ink amount by replacing a relatively large dot with a relatively small dot.
[0011]
In this case, the ink amount is not partially reduced to zero as in the case of thinning out dots, but the amount of ink ejected to a specific contour portion can be reduced, so that white spots can be suppressed. Here, the white spot is a phenomenon in which a part of a line drawing is white.
[0012]
The print control apparatus further includes a print mode selection unit that allows a user to select a print mode including a print resolution as a print mode parameter, and the ink amount reduction unit includes the selected print resolution. Is less than a predetermined resolution, the ink amount is reduced by replacing the dots. If the selected print resolution is equal to or higher than the predetermined resolution, black is printed at the specific contour portion. It is preferable to reduce the amount of ink by regularly decimating a part of dots formed with ink.
[0013]
In this way, the amount of ink is reduced by changing the dot size for low-resolution printing, where white spots are likely to occur when dots are thinned out. The amount can be reduced.
[0014]
In the print control apparatus, the dot data generation unit generates dot data including a plurality of bits of data representing which of the N types of dots is formed in each pixel, and the ink amount reduction unit In the pixel of the specific contour portion, it is preferable that the ink amount is reduced by replacing the dot by changing data of at least one bit among the plurality of bits.
[0015]
In this way, the processing for dot replacement can be easily performed, so that the burden of data processing can be reduced.
[0016]
The print control apparatus further includes a print mode selection unit that allows a user to select a print mode that includes a type of print image having a text option as a print mode parameter, and the ink amount reduction unit includes: The ink amount is preferably reduced when the selection of the type of the print image is text.
[0017]
In this way, it is possible to perform ink amount reduction processing for neatly printing an image in which a line image and a natural image are mixed only when printing an image in which a line image such as text and a natural image such as a photograph are mixed.
[0018]
In the print control apparatus, it is preferable that the ink amount reduction unit reduces the ink amount only when the print medium is plain paper.
[0019]
In this way, ink bleeding can be further suppressed, particularly when text is printed on printing paper such as plain paper that has a small amount of ink absorption.
[0020]
The dot data may include color dot data representing the formation state of color dots formed with color ink in each pixel.
[0021]
The second aspect of the present invention is a print control for generating print data to be supplied to the printing unit in order to perform printing using a printing unit that forms dots on a print medium while performing main scanning of the print head. A dot data generation unit configured to generate dot data representing a dot formation state of each pixel in a print image according to multi-tone image data representing a color of each pixel of an image to be printed; Determining whether or not the color of each pixel is black according to data, and generating a black area extraction data representing a black area where the color of the pixel is black according to the determination; and the determination And a natural image region extraction data generation unit that generates natural image region extraction data that is data obtained by replacing the color of pixels belonging to the black region in the image data from black to another color other than black. The dot A black region black dot data generation unit for generating black region black dot data representing a dot formation state in which each pixel belonging to the black region is filled with black dots in accordance with the black region extraction data A natural image area black dot data generation unit that generates a natural image area black dot data representing a black dot formation state in each pixel by performing a halftone process on the natural image area extraction data, and the natural image area And a dot data combining unit that generates dot data representing a black dot formation state of each pixel by combining the black dot data and the black region black dot data.
[0022]
According to the second aspect of the present invention, dot data representing a dot formation state in which each pixel is filled with black dots is generated for a black region representing a line drawing, and a black representing a line drawing is represented for a region representing a natural image. Since dot data representing the dot formation state is generated from the natural image region extraction data in which the color of the region is replaced with a color other than black, the region representing a line drawing such as text or illustration in which the pixel color is black In an image in which a region representing a natural image and a region representing a natural image are mixed, blurring at the boundary between the line image and the natural image that occurs in the halftone process can be suppressed.
[0023]
The present invention can be realized in various modes. For example, a printing method and a printing apparatus, a printing control method and a printing control apparatus, a computer program for realizing the functions of these methods or apparatuses, and the like The present invention can be realized in the form of a recording medium that records a computer program, a data signal that includes the computer program and is embodied in a carrier wave, and the like.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in the following order based on examples.
A. Device configuration:
B. First embodiment:
C. Second embodiment:
D. Third embodiment:
E. Variations:
[0025]
A. Device configuration:
FIG. 1 is a block diagram showing the configuration of a printing system as an embodiment of the present invention. This printing system includes a computer 88 as a print control device and a color printer 20 as a printing unit. The combination of the color printer 20 and the computer 88 can be called a “printing apparatus” in a broad sense.
[0026]
In the computer 88, an application program 95 operates under a predetermined operating system. A video driver 94 and a printer driver 96 are incorporated in the operating system, and print data PD to be transferred to the color printer 20 is output from the application program 95 via these drivers. The application program 95 performs desired processing on the image to be processed, and displays the image on the CRT 21 via the video driver 94.
[0027]
When the application program 95 issues a print command, the printer driver 96 of the computer 88 receives image data from the application program 95 and converts it into print data PD to be supplied to the color printer 20. In the example shown in FIG. 1, the printer driver 96 includes a resolution conversion module 97, a color conversion module 98, a halftone module 99, a rasterizer 100, a contour line extraction unit 101, and an ink amount reduction unit 102. A print mode selection unit 103, a black determination unit 104, and a color conversion table LUT.
[0028]
The resolution conversion module 97 plays a role of converting the resolution of the color image data handled by the application program 95 (that is, the number of pixels per unit length) into a resolution that can be handled by the printer driver 96. The image data subjected to resolution conversion in this way is still image information composed of three colors of RGB. The color conversion module 98 converts RGB image data into multi-tone data of a plurality of ink colors that can be used by the color printer 20 for each pixel while referring to the color conversion table LUT.
[0029]
The color-converted multi-gradation data has, for example, 256 gradation values. The halftone module 99 executes halftone processing for expressing the gradation value by the color printer 20 by forming the ink dots in a dispersed manner. The halftone data generated by the halftone process is rearranged in the order of data to be transferred to the color printer 20 by the rasterizer 100 and output as final print data PD. The print data PD includes raster data indicating the dot recording state during each main scan and data indicating the sub-scan feed amount. The functions of the contour extraction unit 101, the ink amount reduction unit 102, the print mode selection unit 103, and the black determination unit 104 will be described later.
[0030]
The printer driver 96 corresponds to a program for realizing a function for generating the print data PD. A program for realizing the function of the printer driver 96 is supplied in a form recorded on a computer-readable recording medium. Such recording media include flexible disks, CD-ROMs, magneto-optical disks, IC cards, ROM cartridges, punch cards, printed matter on which codes such as bar codes are printed, computer internal storage devices (such as RAM and ROM). A variety of computer-readable media such as a memory) and an external storage device can be used.
[0031]
FIG. 2 is a schematic configuration diagram of the color printer 20. The color printer 20 includes a sub-scan feed mechanism that transports the printing paper P in the sub-scan direction by the paper feed motor 22 and a main scan feed that reciprocates the carriage 30 in the axial direction (main scan direction) of the platen 26 by the carriage motor 24. Mechanism, a head drive mechanism that drives a print head unit 60 (also referred to as a “print head assembly”) mounted on the carriage 30 to control ink ejection and dot formation, and these paper feed motor 22, carriage motor 24, a control circuit 40 that controls the exchange of signals with the print head unit 60 and the operation panel 32. The control circuit 40 is connected to the computer 88 via the connector 56.
[0032]
The sub-scan feed mechanism for transporting the printing paper P includes a gear train (not shown) that transmits the rotation of the paper feed motor 22 to the platen 26 and a paper transport roller (not shown). Further, the main scanning feed mechanism for reciprocating the carriage 30 has an endless drive belt 36 between the carriage motor 24 and a slide shaft 34 that is installed in parallel with the axis of the platen 26 and slidably holds the carriage 30. And a position sensor 39 for detecting the origin position of the carriage 30.
[0033]
FIG. 3 is a block diagram showing the configuration of the color printer 20 with the control circuit 40 as the center. The control circuit 40 is configured as an arithmetic and logic circuit including a CPU 41, a programmable ROM (PROM) 43, a RAM 44, and a character generator (CG) 45 that stores a dot matrix of characters. The control circuit 40 further includes an I / F dedicated circuit 50 dedicated to interface with an external motor and the like, and a head that is connected to the I / F dedicated circuit 50 and drives the print head unit 60 to eject ink. A drive circuit 52 and a motor drive circuit 54 for driving the paper feed motor 22 and the carriage motor 24 are provided. The I / F dedicated circuit 50 incorporates a parallel interface circuit and can receive print data PD supplied from the computer 88 via the connector 56. The color printer 20 executes printing according to the print data PD. The RAM 44 functions as a buffer memory for temporarily storing raster data.
[0034]
The print head unit 60 has a print head 28 and can be mounted with an ink cartridge. The print head unit 60 is attached to and detached from the color printer 20 as one component. That is, when the print head 28 is to be replaced, the print head unit 60 is replaced.
[0035]
FIG. 4 is an explanatory diagram showing the nozzle arrangement on the lower surface of the print head 28. On the lower surface of the print head 28, a black ink nozzle row K for discharging black ink, a dark cyan ink nozzle row C for discharging dark cyan ink, and a light cyan ink nozzle for discharging light cyan ink. A column LC, a dark magenta ink nozzle row M for discharging dark magenta ink, a light magenta ink nozzle row LM for discharging light magenta ink, and a yellow ink nozzle row Y for discharging yellow ink. Is formed.
[0036]
Each nozzle is provided with a piezo element (not shown) as a drive element for driving each nozzle to eject ink droplets. During printing, ink droplets are ejected from each nozzle while the print head 28 moves in the main scanning direction MS.
[0037]
In the color printer 20 having the hardware configuration described above, the carriage 30 is reciprocated by the carriage motor 24 while the paper P is transported by the paper feed motor 22, and simultaneously the piezo elements of the print head 28 are driven, so that each color ink Droplets are ejected to form ink dots on the paper P to form a multicolor / multi-tone image.
[0038]
B. First embodiment:
FIG. 5 is a flowchart showing the procedure of the printing process in the first embodiment of the present invention. In step S1101, the user instructs the computer 88 to print. In step S1102, when a “property button” (not shown) in the print dialog box displayed on the CRT 21 is clicked, the print mode selection unit 103 (FIG. 1) displays the property setting screen shown in FIG. To display.
[0039]
The user can specify various parameters that define the print mode in the property setting screen. The print mode basic setting screen shown in FIG. 6 includes the following elements for designating various parameters.
(1) Image type selection menu IM: A pull-down menu for selecting one from a list of image types including text and photos.
(2) Paper type menu PM: A pull-down menu for selecting one from a list of paper such as plain paper and inkjet printer paper.
[0040]
The user can also set other parameters on the detailed setting screen of the print mode, but description of these other parameters will be omitted below.
[0041]
In step S1103 of FIG. 5, when the user sets various parameters of the print mode and instructs the start of printing, in step S1104, the black determination unit 104 (FIG. 1) determines the ink amount according to the set print mode. Decide whether or not to reduce. Specifically, when “text” is selected from the image type selection menu IM and “plain paper” is selected from the paper type menu PM, an ink amount reduction process is performed.
[0042]
FIG. 7 is an explanatory diagram showing an example of an image to be processed in the first embodiment of the present invention. This image is obtained by superimposing a black text TXT “HAWAII” on a natural image representing a landscape photograph. The image data representing this image includes image information composed of three colors of RGB, and the gradation values of R, G, and B are all 0 in the area where the text is displayed.
[0043]
FIG. 8 is a block diagram of a system that performs a blur suppression process for a contour portion according to the first embodiment of the present invention. This system includes a resolution conversion module 97, a color conversion module 98, a halftone module 99, a contour line extraction unit 101, an ink amount reduction unit 102, and a black determination unit 104.
[0044]
The RGB image data whose resolution is converted by the resolution conversion module 97 is sent to the color conversion module 98 and the black determination unit 104. The color conversion module 98 converts RGB image data into multi-tone data of a plurality of ink colors that can be used by the color printer 20 for each pixel. The halftone module 99 generates dot data representing a dot formation state for expressing the gradation value by the color printer 20. In this embodiment, the color conversion module 98, the halftone module 99, the contour line extraction unit 101, and the ink amount reduction unit 102 correspond to a dot data generation unit in the claims.
[0045]
The dot data includes a first K plane that represents the formation state of black ink dots before ink amount reduction, a C plane that represents the formation state of dark cyan ink dots, and an LC plane that represents the formation state of light cyan ink dots. , An M plane representing a dark magenta ink dot formation state, an LM plane representing a light magenta ink dot formation state, and a Y plane representing a yellow ink dot formation state.
[0046]
FIG. 9 is an explanatory diagram showing the flow of the blur suppression process for the contour portion in the first embodiment of the present invention. FIG. 9A shows RGB planes included in the RGB image data. In this example, for easy understanding, the gradation values are only 0 and 255 for all the planes. FIG. 9B shows a first K plane representing the formation state of black ink dots before the ink amount reduction process is performed. In this example, since the gradation value of each plane of the RGB image data is only 0 and 255, the pixel whose gradation value is “0” in each RGB plane is “11” in the first K plane, A pixel having a gradation value of “255” in each of the RGB planes has a pixel value of “00” in the first K plane. In the K plane, a relatively large dot that can be filled with black ink is formed so that a solid image can be formed when the pixel value is “11”, and no dot is formed when the pixel value is “00”. .
[0047]
FIG. 9C shows a second K plane representing the formation state of the black ink dots after the ink amount reduction processing is performed. FIG. 9D shows the ink amount reduction data RD. The ink amount reduction process is performed by the ink amount reduction unit 102 using the ink amount reduction data RD. Specifically, the pixel value of the corresponding pixel in the second K plane is changed from “11” to “01” only for the pixel having the pixel value “1” in the ink amount reduction data. A small dot is formed in a pixel having a pixel value “01”. In this way, the large dot is replaced with the small dot by changing only the data of one of the two bits included in the data of each pixel of the K plane.
[0048]
FIG. 10 is an explanatory diagram showing a flow of processing for generating the ink amount reduction data RD. FIG. 10A shows each plane included in the RGB image data, which is the same as that shown in FIG. FIG. 10B shows black area extraction data. The black area extraction data is 1-bit data for each pixel representing the black area extracted from the RGB image data by the black determination unit 104. The black area extraction data is generated by setting the pixel value to 1 only when the gradation values of all the planes of the RGB image data are 0, and setting the pixel value to “0” in other cases. The ink amount reduction data is generated using the black area extraction data.
[0049]
FIG. 10C shows the ink amount reduction data RD. The ink amount reduction data RD is generated as data representing a contour portion that is a pixel forming the contour of the black region. The pixel value of the contour portion is “1”, and the other pixel values are “0”. In this embodiment, the contour portion is a set of pixels that are pixels belonging to the black region and at least one of the pixels adjacent in the vertical and horizontal directions does not belong to the black region.
[0050]
The ink amount reduction data RD is generated by the contour line extraction unit 101 from the black area extraction data using the filter shown in FIG. Specifically, first, calculation is performed by applying this filter to the black region extraction data while paying attention to each pixel. When the calculation result is 1 or more, the pixel value is “1”, and when the calculation result is less than 1, the pixel value is “0”, thereby generating the ink amount reduction data RD. The
[0051]
For example, when attention is paid to the pixel in the 2nd row and the Cth column in FIG. 10B, the result obtained by applying the filter is “2”. At this time, since the calculation result is 1 or more, the pixel value of the pixel in the 2nd row and the Cth column is “1”. When attention is paid to the pixel in the 3rd row and the Cth column in the figure, the result calculated by applying the filter is “0”. At this time, since the calculation result is less than 1, the pixel value of the pixel in the 3rd row and the Cth column is “0”. In this way, in this process, the pixel value is set to “1” only when the pixel value of the pixel of interest is “1” and the pixel value of at least one pixel adjacent to the top and bottom or left and right is “0”. In other cases, the process of setting the pixel value to “0” is performed, and the ink amount reduction data RD is generated.
[0052]
In step S1106 of FIG. 5, the rasterizer 100 (FIG. 1), according to the dot data adjusted in this way, raster data indicating the dot recording state during each main scan and data indicating the sub-scan feed amount. The print data PD including these is generated. In step S <b> 1107, the printer 20 performs printing according to the print data supplied from the computer 88. In this embodiment, the rasterizer 100 and the printer 20 function as a dot forming unit in the claims.
[0053]
As described above, in the first embodiment, the ink amount reduction process is performed only for the black region in which all the RGB values of the image data are zero. On the other hand, since the probability that a black region in which all RGB values are 0 belongs to a natural image region is very low, such a region can be regarded as an artificial line drawing region. As a result, it is possible to suppress blur in the outline of the line drawing by suppressing ink bleeding in the outline of the black area representing the line drawing without degrading the image quality of the area representing the natural image by reducing the ink amount. There are advantages.
[0054]
In this embodiment, whether to perform the ink amount reduction process is determined according to two print mode parameters such as the type of image to be printed and the type of print medium. As a result, the amount of ink can be reduced only when an image including a line drawing such as text is printed on plain paper with slow ink absorption, and bleeding that occurs in the outline of the line drawing in the printed image can be suppressed. There are also advantages.
[0055]
C. Second embodiment:
FIG. 12 is a block diagram of a system that performs a blur suppression process for a contour portion according to the second embodiment of the present invention. The second embodiment differs from the first embodiment in that the black determination unit 104 also generates natural image region extraction data (RGB data). The natural image area extraction data is data in which pixel values of all the planes of the image data representing the image to be printed are replaced with 255 for the pixels with gradation values of 0. That is, the natural image area extraction data is data in which the color of the pixels in the black area is replaced from black to white in the image data (RGB data).
[0056]
The reason why the color of the pixel of the image data is replaced from black to white is to suppress blurring of the outline portion of the line drawing. Blurring of the outline of a line drawing occurs not only due to ink bleeding but also due to halftone processing. For example, when halftone processing is performed at the outline of a line drawing so that the number of gradations is prioritized over the resolution, the surrounding luminance is lowered due to the influence of the line drawing and the outline of the line drawing appears blurred. There is a fear. In this embodiment, the blurring caused by the halftone process is suppressed by replacing the color of the pixel in the black region from black to white.
[0057]
From the natural image area extraction data generated in this way, the color conversion module 98 and the halftone module 99 allow the natural image area black dot data representing the black ink dot formation state in the natural image area and the color dot formation state. And dot data including the color dot data representing. Thus, in this embodiment, the color conversion module 98 and the halftone module 99 function as a natural image region black dot data generation unit in the claims.
[0058]
FIG. 13 is an explanatory diagram showing the flow of black area black dot data generation processing in the second embodiment of the present invention. FIG. 13A shows each plane included in image data (RGB data), FIG. 13B shows black area extraction data, and FIG. 13C shows ink amount reduction data RD. Show. These are the same as those shown in FIGS. 10A, 10B and 10C, respectively.
[0059]
The ink amount reduction unit 102 generates 2-bit black region black dot data subjected to the ink amount reduction process based on the 1-bit black region extraction data and the 1-bit ink amount reduction data RD. Specifically, the black region black dot data is generated by setting the pixel value of the black region extraction data to the first bit of the black region black dot data and setting the value obtained by inverting the pixel value of the ink amount reduction data RD to the black value. This is done by setting the second bit of the area black dot data. For example, paying attention to the pixel in 2 rows and C columns, the pixel value of the black area extraction data is “1”, and the value obtained by inverting the pixel value of the ink amount reduction data RD is “0”. As a result, the pixels in 2 rows and C columns of the black region black dot data have a pixel value of “01”. Thus, in this embodiment, the contour line extraction unit 101 and the ink amount reduction unit 102 function as a black region black dot data generation unit in the claims.
[0060]
The black area black dot data and the natural image area black dot data are combined by the dot data combining unit 105 to generate a K plane representing the black dot formation state in each pixel of the print image. This synthesis can be performed, for example, by calculating the logical sum of each bit of both data in each pixel. Specifically, in a certain pixel, when the pixel value of the black region black dot data is “11” and the pixel value of the natural image region black dot data is “00”, the pixel value in the K plane is “11”.
[0061]
As described above, in this embodiment, since the line data area and the natural image area can be processed separately to generate dot data, the area representing the line image such as text or illustration whose pixel color is black and the natural image area are displayed. There is an advantage that blurring of a contour portion of a line drawing that occurs in halftone processing can be suppressed in an image in which a region representing a drawing is mixed.
[0062]
D. Third embodiment:
FIG. 14 is a block diagram of a system that performs a blur suppression process for a contour portion according to the third embodiment of the present invention. The third embodiment differs from the second embodiment in that the ink amount reduction process is not performed. However, the other points are the same as in the second embodiment.
[0063]
FIG. 15 is an explanatory diagram showing the flow of black area black dot data generation processing in the third embodiment of the present invention. FIG. 15A shows each plane included in the RGB image data, and FIG. 15B shows black area extraction data. These are the same as those shown in FIGS. 10 (a) and 10 (b), respectively.
[0064]
The black determination unit 104 generates 2-bit black area black dot data based on the 1-bit black area extraction data. Specifically, in the 2-bit black region black dot data, the pixel value of the black region extraction data is “00” and the pixel value of the black region extraction data is “1”. The pixel is generated by setting the pixel value to “11”.
[0065]
The black area black dot data and the natural image area black dot data are synthesized by the dot data synthesis unit 105, and a K plane representing the black dot formation state in each pixel of the print image is generated in the same manner as in the second embodiment. The Thus, in this embodiment, the black determination unit 104 also functions as a black region black dot data generation unit in the claims.
[0066]
As described above, even if the line drawing area and the natural image area are separately processed without performing the ink amount reduction process, the halftone process is performed in an image in which the line drawing area and the natural image area are mixed. It is also possible to suppress blurring of the outline of the line drawing that occurs.
[0067]
E. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.
[0068]
E-1. In the above embodiment, the image data to be printed is RGB data, but it may be YCbCr data, for example. In general, the image data processed in the present invention may be multi-gradation data representing the color of each pixel of the image to be printed. When the image data is YCbCr data, a pixel value corresponding to the gradation value of all the planes of the RGB image data is 0, that is, a pixel having a pixel value of Y = 0 and Cb = Cr = 128. It belongs to the black area.
[0069]
E-2. In the above-described embodiment, the ink amount reduction unit reduces the ink amount for all the pixels forming the outline of the black area. For example, among the pixels forming the outline of the black area, the outline parallel to the main scan is used. The amount of ink may be reduced only for the pixels forming the. In general, in the present invention, the amount of ink ejected to at least some of the pixels forming the outline of the black region may be reduced.
[0070]
E-3. In the above embodiment, the ink amount is reduced by replacing a relatively large dot with a relatively small dot regardless of the print resolution. For example, only when the print resolution is a predetermined resolution or less, the dot amount is reduced. The ink amount may be reduced by replacing the ink amount, and when the printing resolution is equal to or higher than a predetermined resolution, the ink amount may be reduced by regularly thinning out some dots.
[0071]
If ink dots are thinned out when the print resolution is low, white spots are likely to occur.However, if the dots are thinned out, white spots are likely to occur. In the case of high resolution where white spots are unlikely to occur, there is an advantage that the ink amount can be easily reduced by thinning out dots.
[0072]
E-4. In the above embodiment, the natural image area extraction data is data in which the color of the pixel belonging to the black area in the image data is replaced from black to white, but it may be replaced with the color of an adjacent pixel or a neighboring pixel. It may be replaced with the average value of. In general, the natural image area extraction data used in the present invention may be data obtained by replacing the color of the pixel belonging to the black area in the image data with a color other than black.
[0073]
E-5. In the above embodiment, the print mode parameter used to determine whether or not to reduce the ink amount includes the type of print medium. For example, the type of ink such as super penetrating ink or slow penetrating ink is used. You may decide.
[0074]
Here, the terms “super penetrating ink” and “slow penetrating ink” refer to the relative properties of these inks. That is, when the same amount is dropped on a standard print medium (for example, plain paper), the super-penetrating ink penetrates into the print medium faster than the slow-penetrating ink. For example, as a super-penetrating ink, the surface tension at about 20 ° C. is about 40 × 10. ^-3 Ink less than N / m can be used. Further, as the slow penetration ink, the surface tension at about 20 ° C. is about 40 × 10. ^-3 Inks exceeding N / m can be used. Note that both dyes and pigments can be used as the coloring material for the super-penetrating ink and the slow-penetrating ink.
[0075]
E-6. In the above embodiment, the type of the print medium is specified by selecting the print mode. However, the print medium may be specified by installing a means for automatically specifying the type of the print medium in the printing apparatus.
[0076]
As a means for automatically specifying the type of print medium, for example, a light specifying means for identifying and specifying reflected light based on a difference in light reflectance between dedicated paper and plain paper, a recording medium or its packaging in advance. There are bar code reading means for specifying by reading a bar code attached to a material, and means for specifying using an IC reader. Such means has the advantage that no user operation is required to specify the type of print medium, and the means specified by selecting the print mode has the advantage that it can be realized with a simple configuration.
[0077]
E-7. In the above embodiment, the area representing the line image is superimposed on the area representing the natural image, but the present invention can also be applied to the case where each area exists in another place on the print medium of the same page. In general, the present invention can be applied to printing an image in which a region representing a natural image and a region representing a line image are mixed.
[0078]
E-8. The present invention can be applied not only to color printing but also to printing monochrome multi-tone images. In this case, the natural image area extraction data is monochrome multi-gradation data. Further, the present invention can be applied to printing that expresses multiple gradations by expressing one pixel with a plurality of ink dots. It can also be applied to a drum printer. In the drum printer, the drum rotation direction is the main scanning direction, and the carriage traveling direction is the sub-scanning direction. In addition, the present invention can be applied not only to an ink jet printer but also to an ink dot recording apparatus that generally records on the surface of a print medium using a print head having a plurality of nozzle rows.
[0079]
E-9. In the above embodiment, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced by hardware. For example, part or all of the functions of the printer driver 96 shown in FIG. 1 can be executed by the control circuit 40 in the printer 20. In this case, a part or all of the functions of the computer 88 as a print control apparatus for creating print data is realized by the control circuit 40 of the printer 20.
[0080]
When some or all of the functions of the present invention are realized by software, the software (computer program) can be provided in a form stored in a computer-readable recording medium. In the present invention, the “computer-readable recording medium” is not limited to a portable recording medium such as a flexible disk or a CD-ROM, but an internal storage device in a computer such as various RAMs and ROMs, a hard disk, and the like. An external storage device fixed to the computer is also included.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the configuration of a printing system as an embodiment of the present invention.
FIG. 2 is an explanatory diagram illustrating a configuration of a printer.
3 is a block diagram showing a configuration of a control circuit 40 in the color printer 20. FIG.
FIG. 4 is an explanatory diagram showing a nozzle arrangement on the lower surface of the print head.
FIG. 5 is a flowchart illustrating a printing processing procedure according to the first embodiment of the present invention.
6 is a diagram showing an example of a basic setting screen for a print mode displayed on a CRT 21. FIG.
FIG. 7 is an explanatory diagram showing an example of an image to be processed in the first embodiment of the present invention.
FIG. 8 is a block diagram of a system that performs a blur suppression process for a contour portion according to the first embodiment of the present invention.
FIG. 9 is an explanatory diagram showing a flow of a blur suppression process for a contour portion in the first embodiment of the present invention.
FIG. 10 is an explanatory diagram showing a flow of processing for generating ink amount reduction data.
FIG. 11 is an explanatory diagram showing a calculation process used for generating ink amount reduction data.
FIG. 12 is a block diagram of a system that performs a blur suppression process for a contour portion according to a third embodiment of the present invention.
FIG. 13 is an explanatory diagram showing a flow of black area black dot data generation processing in a third embodiment of the present invention.
FIG. 14 is a block diagram of a system that performs a blur suppression process for a contour portion according to a second embodiment of the present invention.
FIG. 15 is an explanatory diagram showing a flow of black area black dot data generation processing in the second embodiment of the present invention;
[Explanation of symbols]
20 Color printer
21 ... CRT
22 ... Paper feed motor
24 ... Carriage motor
26 ... Platen
28 ... Print head
30 ... carriage
32 ... Control panel
34 ... Sliding shaft
36 ... Drive belt
38 ... pulley
39 ... Position sensor
40 ... Control circuit
41 ... CPU
44 ... RAM
50 ... I / F dedicated circuit
52. Head drive circuit
54 ... Motor drive circuit
56 ... Connector
60 ... print head unit
88 ... Computer
94 ... Video driver
95 ... Application program
96 ... Printer driver
97 ... Resolution conversion module
98 ... Color conversion module
99 ... Halftone module
100 ... Rasterizer
101 ... Outline extraction unit
102: Ink amount reduction unit
103: Print mode selection section
104 ... Black judgment part
105... Dot data composition unit

Claims (3)

A printing control device that generates print data to be supplied to the printing unit in order to perform printing using a printing unit that forms dots on a print medium while performing main scanning of the print head,
A dot data generation unit that generates dot data representing a dot formation state of each pixel in the print image according to multi-tone image data representing the color of each pixel of the print target image;
A black determination unit that determines whether the color of each pixel is black according to the image data, and generates black region extraction data representing a black region where the color of the pixel is black according to the determination; ,
A contour line extraction unit that extracts a specific contour portion that is at least a part of pixels forming the contour of the black region from the pixels belonging to the black region according to the black region extraction data;
An ink amount reducing unit that adjusts the dot data so as to reduce the ink amount of dots formed with black ink in the specific contour portion;
A print mode selection unit that allows a user to select a print mode including a print resolution as a print mode parameter;
The printing unit includes a plurality of nozzles and a plurality of ejection driving elements for ejecting ink droplets from the plurality of nozzles, respectively, and each nozzle has a different size in a region of one pixel on the print medium. A print head capable of selectively forming any of N types of dots (N is an integer of 2 or more);
When the selected print resolution is less than a predetermined resolution, the ink amount reduction unit replaces a relatively large dot of the N types of dots with a relatively small dot. If the selected print resolution is equal to or higher than the predetermined resolution, the ink amount can be reduced by regularly thinning out a part of dots formed with black ink in the specific contour portion. A printing control apparatus characterized in that: The print control apparatus according to claim 1,
The black determination unit generates natural image region extraction data that is data in which the color of pixels belonging to the black region in the image data is replaced with a color other than black.
The dot data generation unit
According to the black area extraction data, a black area black dot data generation unit that generates black area black dot data representing a dot formation state in which each pixel belonging to the black area is filled with black dots;
A natural image region black dot data generation unit that generates natural image region black dot data representing a black dot formation state in each pixel by performing halfton processing on the natural image region extraction data;
A dot data combining unit that generates dot data representing a black dot formation state of each pixel by combining the natural image region black dot data and the black region black dot data;
A printing control apparatus comprising: The print control apparatus according to claim 1 or 2,
The dot data generation unit generates dot data including data of a plurality of bits indicating which of the N types of dots is formed in each pixel,
The ink amount reduction unit reduces the ink amount by replacing the dots by changing data of at least one of the plurality of bits in the pixel of the specific contour portion. .

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