JP2003048340A - Printing by suppressing blurring of outline - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress blurring of an outline part of line images in an image in which regions expressing natural images and regions expressing line images are mixed. SOLUTION: Black region extraction data for expressing black regions in which a pixel color is black is generated according to multi-gradation image data, and at the same time, at least a part of pixels for forming outlines of the black regions is extracted according to the black region extraction data. Printing data is adjusted so that an ink amount of black ink dots to be formed to the extracted pixels is reduced. Accordingly, blurring due to bleeding of ink which is brought about to the outline part of line images can be suppressed without extraordinarily degrading the image quality of natural images in the image in which regions expressing line images such as a text or an illustration having a black pixel color and regions expressing natural images are mixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for ejecting ink to print an image on a print medium.

[0002]

2. Description of the Related Art Recently, as an output device of a computer,
Ink jet printers that eject several colors of ink from an ink head have become widespread and are widely used for printing images processed by a computer in multiple colors and multiple gradations.

When a line drawing such as characters and illustrations is printed by an ink jet printer, the outline portion of the line drawing may be blurred. Such blurring of the outline portion is suitable for a natural image such as a photograph for an image representing a line drawing, or an outflow of ink from an ink reservoir generated when the ink ejected in the line drawing area cannot be completely absorbed by the print medium. This is due to performing halftone processing.

[0004]

In order to suppress such blurring, a method of reducing the ink amount of dots forming the contour portion of a line drawing can be considered. However, if such a method is applied to an image such as a photograph in which a natural image and an artificial line drawing are mixed, the amount of ink in the area representing the natural image is reduced, which deteriorates the image quality of the natural image. There was a fear. Further, in printing an image in which a natural image and a line drawing are mixed, it is difficult to perform the halftone processing that makes the image quality of the natural image and the image quality of the line image compatible with each other. It was.

The present invention has been made in order to solve the above-mentioned problems in the prior art, and excessively deteriorates the image quality of a natural image in an image in which a region representing a natural image and a region representing a line image are mixed. The purpose is to suppress blurring that occurs in the contour portion of a line drawing.

[0006]

In order to solve at least a part of the above-mentioned problems, a first aspect of the present invention is to form dots on a print medium while performing main scanning of a print head. In order to print using the printing unit,
A print control device for generating print data to be supplied to the printing unit, wherein a dot formation state of each pixel in a print image is changed according to multi-tone image data representing a color of each pixel of a print target image. A dot data generation unit that generates dot data that represents, and determines whether or not the color of each pixel is black according to the image data, and determines a black area in which the pixel color is black according to the determination. A black determination unit that generates black region extraction data that represents, and a specific contour that is at least a part of pixels that form the contour of the black region from pixels that belong to the black region according to the black region extraction data. And an ink amount reducing unit that adjusts the dot data so as to reduce the ink amount of dots formed by black ink in the specific contour portion.

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 contour of the black region, so that the line drawing can be performed without excessively degrading the image quality of the natural image. It is possible to suppress blurring due to ink bleeding that occurs in the contour portion of the.

In the print control apparatus, the black determination unit generates natural image area extraction data which is data in which the color of a pixel belonging to the black area in the image data is replaced with black other than black. Then, the dot data generation unit 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 according to the black area extraction data. A data generation unit, a natural image region black dot data generation unit that generates a natural image region black dot data indicating a black dot formation state in each pixel by performing halftoning on the natural image region extraction data, Each pixel by combining the natural image area black dot data and the black area black dot data It is preferable to include a dot data synthesizing unit that generates dot data representing the formation state of the black dots.

In this way, 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 natural image region extraction data is created for a natural image region representing a natural image. On the other hand, since halftone processing is performed to generate dot data representing the dot formation state, it is possible to suppress not only blurring caused by ink bleeding but also blurring of the contour portion of the line drawing caused by halftone processing. .

In the above print control apparatus, the printing unit has a plurality of nozzles and a plurality of ejection drive elements for ejecting ink droplets from the plurality of nozzles, and each nozzle is used to print on a print medium. A print head capable of selectively forming any of N types of dots (N is an integer of 2 or more) having different sizes in the area of 1 pixel, and the ink amount reduction unit is configured to perform the N types of dots. It is preferable to replace the relatively large dot with a relatively small dot to reduce the ink amount.

In this way, it is possible to reduce the amount of ink ejected to a specific contour portion, instead of partially reducing the amount of ink to zero as in the case of thinning out dots, and thus suppressing white spots. You can Here, the whiteout refers to a phenomenon in which a part of the line drawing is whitened out.

The print control apparatus further includes a print mode selection unit that allows the user to select a print mode including print resolution as a parameter of the print mode, and the ink amount reduction unit is selected by the selection unit. If the printing resolution is lower than a predetermined resolution, the amount of ink is reduced by replacing the dots. If the selected printing resolution is higher than the predetermined resolution, the specific contour is deleted. It is preferable that the amount of ink be reduced by regularly thinning out some of the dots formed by black ink in some parts.

In this way, the amount of ink is reduced by changing the dot size in low resolution printing in which white spots tend to occur when dots are thinned out, and by thinning out dots in the high resolution case where white spots are hard to occur. The amount of ink can be easily reduced.

In the above print control device, the dot data generation unit generates dot data including a plurality of bits of data indicating which of the N types of dots is formed in each pixel, and the ink amount It is preferable that the reduction unit reduces the ink amount by replacing the dot by changing the data of at least one bit of the plurality of bits in the pixel of the specific contour portion.

In this way, the processing for dot replacement can be easily performed, and the load of data processing can be reduced.

The print control apparatus further includes a print mode selection unit that allows the user to select a print mode including a type of a print image having a text option as a print mode parameter, and the ink amount. The reduction unit preferably reduces the ink amount when the type of the print image is selected as text.

In this way, only when printing an image in which a line drawing such as text and a natural image such as a photo are mixed, it is possible to perform an ink amount reduction process for printing an image in which a line drawing and a natural image are mixed.

In the above print control apparatus, it is preferable that the ink amount reduction unit reduces the ink amount only when the print medium is plain paper.

This makes it possible to further suppress ink bleeding, especially when text is printed on printing paper such as plain paper that absorbs a small amount of ink.

The dot data may include color dot data representing the formation state of color dots formed by color ink in each pixel.

A second aspect of the present invention is to generate print data to be supplied to the printing unit in order to perform printing using the printing unit that forms dots on the printing medium while performing main scanning of the printing head. And a dot data generation unit that generates dot data indicating a dot formation state of each pixel in the print image in accordance with multi-tone image data indicating the color of each pixel of the print target image. A black determination unit that determines whether or not the color of each pixel is black according to the image data, and generates black region extraction data that represents a black region in which the pixel color is black according to the determination. According to the determination, a natural image region extraction data generation unit that generates natural image region extraction data, which 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 from black. With and The dot data generation unit generates black region black dot data that generates black region black dot data indicating 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. Unit, a natural image region black dot data generation unit that generates a natural image region black dot data indicating a formation state of a black dot in each pixel by performing halftoning on the natural image region extraction data, and the natural image It is characterized by further comprising: a dot data synthesizing unit for synthesizing the area black dot data and the black area black dot data to generate dot data representing a formation state of a black dot of each pixel.

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 area representing a line drawing, and line drawing is created for an area representing a natural image. Since the dot data representing the dot formation state is generated from the natural image region extraction data in which the color of the black region that represents is replaced with a color other than black, line drawings such as text and illustrations in which the pixel color is black It is possible to suppress blurring of a boundary portion between a line image and a natural image that occurs in the halftone processing in an image in which a region that represents the image and a region that represents the natural image are mixed.

The present invention can be implemented in various modes, for example, a printing method and a printing device,
Print control method and print control apparatus, computer program for realizing functions of those methods or apparatuses,
It can be realized in the form of a recording medium recording the computer program, a data signal containing the computer program and embodied in a carrier wave, or the like.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described in the following order based on examples. A. Device Configuration: B. First Example: C.I. Second embodiment: D. Third Example: E. Modification:

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, a color printer 20 as a printing unit,
Is equipped with. The combination of the color printer 20 and the computer 88 can be called a “printing device” in a broad sense.

In the computer 88, the application program 9 is executed under a predetermined operating system.
5 is working. A video driver 94 and a printer driver 96 are incorporated in the operating system, and the 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 also displays the image on the CRT 21 via the video driver 94.

When the application program 95 issues a print command, the printer driver 9 of the computer 88
6 receives the 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, inside the printer driver 96, a resolution conversion module 97, a color conversion module 98, a halftone module 99, a rasterizer 100, and a contour line extraction unit 10 are provided.
1, an ink amount reduction unit 102, and a print mode selection unit 10
3, a black determination unit 104, and a color conversion table LUT.

The resolution conversion module 97 plays a role of converting the resolution (that is, the number of pixels per unit length) of the color image data handled by the application program 95 into the resolution that can be handled by the printer driver 96. The image data whose resolution has been converted in this way is still image information consisting of three colors of RGB. The color conversion module 98 converts the RGB image data into multi-tone data of a plurality of ink colors usable by the color printer 20 for each pixel while referring to the color conversion table LUT.

The color-converted multi-tone data is, for example, 25
It has 6 gradation values. The halftone module 99 disperses and forms ink dots,
The color printer 20 executes halftone processing for expressing the gradation value. The halftone data generated by the halftone process is rearranged by the rasterizer 100 in the order of data to be transferred to the color printer 20, and is output as final print data PD. In addition,
The print data PD includes raster data indicating a dot recording state at each main scan and data indicating a sub-scan feed amount. Note that the contour extraction unit 101, the ink amount reduction unit 102, the print mode selection unit 103, and the black determination unit 10
Each function of 4 will be described later.

The printer driver 96 corresponds to a program for realizing the function of generating the print data PD. The program for realizing the functions of the printer driver 96 is supplied in the form recorded in a computer-readable recording medium. Examples of such a recording medium include a flexible disk, a CD-ROM, a magneto-optical disk, an IC card, a ROM cartridge, a punch card, a printed matter on which codes such as a bar code are printed, and an internal storage device (RAM, ROM, etc.) of a computer. memory)
Also, various computer-readable media such as an external storage device can be used.

FIG. 2 is a schematic configuration diagram of the color printer 20. The color printer 20 includes a sub-scan feed mechanism that conveys the print 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, the paper feed motor 22, and the carriage motor. 24, print head unit 60 and operation panel 32
And a control circuit 40 that controls the exchange of signals with the. The control circuit 40 is connected to the computer 88 via the connector 56.

The sub-scan feed mechanism for conveying the printing paper P is
A gear train (not shown) that transmits the rotation of the paper feed motor 22 to a platen 26 and a paper transport roller (not shown) is provided. Further, the main scanning feed mechanism for reciprocating the carriage 30 is provided in parallel with the axis of the platen 26, and a drive shaft 36 which is endless between the slide shaft 34 which slidably holds the carriage 30 and the carriage motor 24. And a position sensor 39 for detecting the origin position of the carriage 30.

FIG. 3 is a block diagram showing the configuration of the color printer 20 centering on the control circuit 40. The control circuit 40 includes a CPU 41 and a programmable ROM (PRO
M) 43, a RAM 44, and a character generator (CG) 45 that stores a dot matrix of characters, and is configured as an arithmetic logic operation circuit. The control circuit 40 further has an I / F dedicated circuit 50 dedicated to interface with an external motor and the like, and a head connected to the I / F dedicated circuit 50 for driving the print head unit 60 to eject ink. A drive circuit 52 and a motor drive circuit 54 that drives the paper feed motor 22 and the carriage motor 24 are provided. The I / F dedicated circuit 50 has a built-in parallel interface circuit and has a connector 5
The print data PD supplied from the computer 88 via 6 can be received. The color printer 20
Printing is executed according to this print data PD. In addition, R
The AM 44 functions as a buffer memory for temporarily storing raster data.

The print head unit 60 includes the print head 2
8 and an ink cartridge can be mounted. 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 replaced, the print head unit 60 is replaced.

FIG. 4 is an explanatory view 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 ejecting black ink, a dark cyan ink nozzle row C for ejecting dark cyan ink, and a light cyan ink nozzle for ejecting light cyan ink. Row LC, dark magenta ink nozzle row M for ejecting dark magenta ink, and light magenta ink nozzle row L for ejecting light magenta ink
M and a yellow ink nozzle row Y for ejecting yellow ink are formed.

Each nozzle is provided with a piezo element (not shown) as a driving element for driving each nozzle to eject ink droplets. When printing, print head 2
Ink droplets are ejected from each nozzle while 8 moves in the main scanning direction MS.

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 conveyed by the paper feed motor 22, and at the same time the piezo element of the print head 28 is driven. , Ink droplets of each color are ejected to form ink dots, and a multi-color multi-tone image is formed on the paper P.

B. First Embodiment: FIG. 5 is a flow chart showing the procedure of a printing process in the first embodiment of the present invention. In step S1101, the user uses the computer 8
8 is instructed to print. In step S1102, when the "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. 6 on the CRT 21. To display.

The user can specify various parameters that define the print mode on 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 papers such as plain paper and paper dedicated to inkjet printers.

It should be noted that the user can set other parameters other than these on the detailed setting screen of the print mode, but description of these other parameters will be omitted below.

In step S1103 of FIG. 5, when the user sets various parameters of the print mode and gives an instruction to start printing, in step S1104, the black determination unit 104 (FIG. 1) responds to the set print mode. Determines whether to reduce the ink amount. Specifically, when “text” is selected in the image type selection menu IM and “plain paper” is selected in the paper type menu PM, the ink amount reduction processing is performed.

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 a natural image representing a landscape photograph with black text TXT "HAWAII" superimposed. The image data representing this image includes image information composed of three colors of RGB, and in the area where the text is displayed,
The gradation values of R, G, and B are all 0.

FIG. 8 is a block diagram of a system for performing the blurring suppression processing of the contour portion in 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 are included.

The RGB image data whose resolution has been converted by the resolution conversion module 97 is the color conversion module 98.
To the black determination unit 104. Color conversion module 98
Converts the RGB image data into multi-tone data of a plurality of ink colors usable 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 in the color printer 20. In this embodiment, the color conversion module 98, the halftone module 99, the contour extraction unit 101, and the ink amount reduction unit 102.
And correspond to the dot data generation unit in the claims.

In the dot data, the first K plane showing the formation state of black ink dots before ink amount reduction, the C plane showing the formation state of dark cyan ink dots, and the formation state of light cyan ink dots are shown. LC plane, M plane showing the formation state of dark magenta ink dots, and LM showing the formation state of light magenta ink dots
A plane and a Y plane representing the formation state of the yellow ink dots are included.

FIG. 9 is an explanatory diagram showing the flow of blurring suppressing processing for the contour portion in the first embodiment of the present invention. Figure 9
(A) shows each of the RGB planes included in the RGB image data. In this example, in order to make the explanation easy to understand, the gradation values are 0 and 255 for all planes.
Only trying. FIG. 9B shows a first state of black ink dot formation before the ink amount reduction process is performed.
Shows the K plane. In this example, since the gradation values of each plane of the RGB image data are only 0 and 255, R
In each plane of GB, the pixel whose gradation value is "0" is the first
In the K plane, the pixel value is "11", and in the RGB planes, the pixel having the gradation value "255" is the first K pixel.
In the plane, the pixel value is “00”. In the K plane, when the pixel value is “11”, a relatively large dot that can fill each pixel with black ink is formed so that a solid image can be formed, and when the pixel value is “00”, no dot is formed. .

FIG. 9C shows a second K representing the state of formation of black ink dots after the ink amount reduction processing is performed.
The plane is shown. FIG. 9D shows the ink amount reduction data RD. The ink amount reduction processing 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 whose pixel value of the ink amount reduction data is "1".
In addition, a small dot is formed in a pixel having a pixel value of "01". In this way, by changing only the data of one bit of the two bits included in the data of each pixel of the K plane, the large dots are replaced by the small dots.

FIG. 10 is an explanatory diagram showing the flow of the process of generating the ink amount reduction data RD. FIG. 10A shows RG.
Each plane included in the B image data is shown in FIG.
Is the same as that shown in. 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 generation of the black area extraction data is performed 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 this black area extraction data.

FIG. 10C shows the ink amount reduction data RD.
Is shown. The ink amount reduction data RD is generated as data representing an outline portion which is a pixel forming an outline of a black region. The pixel value of the contour portion is "1", and the other pixel values are "0". In the present embodiment, the contour portion is a set of pixels that belong to the black area and at least one of the vertically, horizontally and adjacently adjacent pixels does not belong to the black area.

The ink amount reduction data RD is obtained from the black area extraction data by using the filter shown in FIG.
Generated by 01. Specifically, first, focusing on each pixel, this filter is applied to the black region extraction data for calculation. When the calculation result is 1 or more, the pixel value is set to "1", and when the calculation result is less than 1, the pixel value is set to "0", whereby the ink amount reduction data R
D is generated.

For example, focusing on the pixel on the 2nd row and the Cth column in FIG. 10B, the result calculated by applying the filter is "2".
Becomes 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”. Further, focusing on 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, the calculation result is less than 1, so 3
The pixel value of the pixel in row C column is “0”. As described above, in this process, the pixel value of the pixel of interest is “1”, and
The pixel value is set to "1" only when the pixel value of at least one of the vertically and horizontally adjacent pixels is "0", and the pixel value is set to "0" in other cases. ,
Ink amount reduction data RD has been generated.

In step S1106 of FIG. 5, the rasterizer 100 (FIG. 1) determines, in accordance with the dot data thus adjusted, the raster data indicating the dot recording state at each main scan and the sub-scan feed amount. And the print data PD including the data indicating In addition, step S11
In 07, the printer 20 executes 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.

As described above, in the first embodiment, the ink amount reduction processing is performed only for the black area in which all the RGB values of the image data are 0. On the other hand, since the probability that a black area in which all RGB values are 0 belongs to a natural image area is extremely low, such an area can be regarded as an artificial line drawing area. As a result, it is possible to suppress blurring of ink in the contour portion of the black area representing the line drawing and suppress blurring in the contour portion of the line drawing without deteriorating the image quality of the area representing the natural image by reducing the ink amount. There are advantages.

Further, in this embodiment, it is determined whether or not the ink amount reduction processing is performed 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 ink amount reduction process can be performed only when an image including a line drawing such as text is printed on plain paper, which absorbs ink slowly, and bleeding that occurs in the contour of the line drawing in the printed image can be suppressed. There are also advantages.

C. Second Embodiment: FIG. 12 shows a second embodiment of the present invention.
FIG. 6 is a block diagram of a system that performs a blurring suppressing process for a contour portion according to the embodiment. In the second embodiment, the black determination unit 10
4 differs from the first embodiment in that natural image area extraction data (RGB data) is also generated. The natural image area extraction data is data in which the pixel values of all the planes of the image data representing the image to be printed whose gradation value is 0 are replaced with 255. That is, the natural image area extraction data is data in which the color of the pixel in the black area is replaced from black to white in the image data (RGB data).

The reason why the pixel color of the image data is changed from black to white is to suppress the blurring of the outline portion of the line drawing.
Blurring of the outline portion of a line drawing is caused not only by ink bleeding but also by halftone processing. For example, if halftone processing is performed in which the number of gradations is prioritized over the resolution in the contour portion of the line drawing, the luminance of the surrounding area is reduced due to the influence of the line drawing, and the contour portion 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 area with black instead of white.

From the natural image area extraction data generated in this way, the color conversion module 98 and the halftone module 99 use the natural image area black dot data representing the formation state of black ink dots in the natural image area and the color dot. And dot data including the color dot data representing the formation state of. As described above, in this embodiment, the color conversion module 98 and the halftone module 99 function as the natural image area black dot data generation unit in the claims.

FIG. 13 is an explanatory diagram showing the flow of the black area black dot data generation processing in the second embodiment of the present invention. FIG. 13A shows each plane included in the image data (RGB data), and FIG.
Shows the black area extraction data, and FIG. 13C shows the ink amount reduction data RD. These are the same as those shown in FIGS. 10A, 10B, and 10C, respectively.

The ink amount reduction unit 102 generates 2-bit black region black dot data subjected to the ink amount reduction processing based on the 1-bit black region extraction data and the 1-bit ink amount reduction data RD. To generate the black area black dot data, specifically, the pixel value of the black area extraction data is set to the first bit of the black area black dot data, and the value obtained by inverting the pixel value of the ink amount reduction data RD is black. This is performed by setting the second bit of the area black dot data. For example, focusing on the pixels in the 2nd row and the Cth column, the pixel value of the black region extraction data is “1”, and the inverted value of the ink amount reduction data RD is “0”. As a result, the pixel in the second row and the C-th column of the black area black dot data has a pixel value of "01". As described above, in this embodiment, the contour line extraction unit 101 and the ink amount reduction unit 102 function as the black area black dot data generation unit in the claims.

The black area black dot data and the natural image area black dot data are combined into the dot data synthesizing unit 10
5, the K plane representing the formation state of the black dot in each pixel of the print image is generated. This synthesis can be performed, for example, by taking the logical sum of each bit of both data in each pixel. Specifically, when the pixel value of the black area black dot data is “11” and the pixel value of the natural image area black dot data is “00” in a certain pixel, the pixel value in the K plane is It becomes "11".

As described above, in this embodiment, since the line drawing area and the natural drawing area can be processed separately to generate dot data, a line drawing such as a text or an illustration in which the pixel color is black is represented. In an image in which a region and a region representing a natural image are mixed, there is an advantage that it is possible to suppress blurring of the outline portion of the line image that occurs in the halftone process.

D. Third Embodiment: FIG. 14 shows a third embodiment of the present invention.
FIG. 6 is a block diagram of a system that performs a blurring suppressing process for a contour portion according to the embodiment. The third embodiment is different from the second embodiment in that the ink amount reduction process is not performed. However, other points are the same as in the second embodiment.

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 shown in FIG.
They are the same as those shown in (a) and (b), respectively.

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 area black dot data, the pixel value of the pixel whose black area extraction data is "0" is "00", and the pixel value of the black area extraction data is "1". For pixels, set the pixel value to "11".
It is generated by

The black area black dot data and the natural image area black dot data are combined into the dot data synthesizing unit 10
5, the 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. Thus, in this embodiment, the black determination unit 104 also functions as the black area black dot data generation unit in the claims.

As described above, by separately processing the line drawing area and the natural image area without performing the ink amount reduction processing, in an image in which a line drawing area and a natural image area are mixed, It is also possible to suppress the blurring of the contour portion of the line drawing that occurs in the tone processing.

E. Modifications: The present invention is not limited to the above-described embodiments and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are also possible. is there.

E-1. In the above embodiment, the image data to be printed is RGB data, but for example YC
It may be bCr data. In general, the image data processed by the present invention may be multi-tone data representing the color of each pixel of the image to be printed. The image data is YCb.
In the case of Cr data, a pixel value corresponding to a gradation value of 0 for all planes of RGB image data, that is, Y =
Pixels having a pixel value of 0 and Cb = Cr = 128 belong to the black area.

E-2. In the above embodiment, the ink amount reducing unit reduces the ink amount for all the pixels forming the contour of the black region. For example, among the pixels forming the contour of the black region, the contour parallel to the main scanning is used. It is also possible to reduce the ink amount only for the pixels forming the.
Generally, in the present invention, the amount of ink ejected to at least some of the pixels forming the contour of the black region may be reduced.

E-3. In the above-described embodiment, the ink amount is reduced by replacing a relatively large dot with a relatively small dot regardless of the printing resolution. The amount of ink is reduced by replacement,
When the printing resolution is equal to or higher than a predetermined resolution, some dots may be regularly thinned to reduce the ink amount.

When thinning out ink dots when the printing resolution is low, white spots are likely to occur. However, in this way, white spots are likely to occur when thinning out dots. In low resolution printing, the amount of ink is changed by changing the dot size. In the case of high resolution in which white spots are unlikely to occur, there is an advantage that the ink amount can be easily reduced by thinning out dots.

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 the adjacent pixel or the neighboring pixel. You may replace with the average value of. Generally, the natural image region extraction data used in the present invention may be data in which the color of the pixel belonging to the black region in the image data is replaced with a color other than black.

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. However, for example, the ink type such as super-penetration ink or slow-penetration ink is used. You may decide.

Here, the terms "super-penetration ink" and "slow-penetration ink" refer to the relative characteristics of these inks. That is, when the same amount is dropped on a standard print medium (for example, plain paper), the super-penetration ink penetrates the print medium faster than the slow-penetration ink. For example, an ink having a surface tension at about 20 ° C. of less than about 40 × 10 ⁻³ N / m can be used as the super-penetration ink. Further, as the slow penetration ink, an ink having a surface tension at about 20 ° C. of more than about 40 × 10 ⁻³ N / m can be used. It is possible to use either a dye or a pigment as the coloring material for the super-penetration ink or the slow-penetration ink.

E-6. In the above embodiment, the type of print medium is specified by selecting the print mode, but it may be specified by equipping the printing apparatus with means for automatically specifying the type of print medium.

As means for automatically specifying the type of print medium, for example, an optical specifying means for identifying and specifying reflected light based on a difference in light reflectance of special paper or plain paper, or a recording medium in advance. Bar code reading means for specifying by reading the bar code attached to the packaging material or its packaging material, I
There is a means to specify using the C reader. Such means has an advantage that no user operation is required to specify the type of print medium, and the means specified by selecting the print mode can be realized with a simple configuration.

E-7. In the above-described embodiment, the area representing the line drawing is superimposed on the area representing the natural image, but the present invention can be applied to the case where the areas are present at different places on the print medium of the same page. Generally, the present invention can be applied to the case of printing an image in which a region representing a natural image and a region representing a line drawing are mixed.

E-8. The present invention can be applied not only to color printing but also to monochrome multi-tone image printing. In this case, the natural image area extraction data is monochrome multi-gradation data. It can also be applied to printing in which multiple gradations are expressed by expressing one pixel with a plurality of ink dots. Also,
It can also be applied to drum printers. In the drum printer, the drum rotation direction is the main scanning direction and the carriage traveling direction is the sub scanning direction. Further, 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.

E-9. In the above embodiment, part of the configuration realized by hardware may be replaced with software, or conversely, part of the structure realized by software may be replaced with hardware. For example, some or all of the functions of the printer driver 96 shown in FIG.
Alternatively, the control circuit 40 therein may be executed.
In this case, the control circuit 40 of the printer 20 realizes some or all of the functions of the computer 88 as a print control device that creates print data.

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, "computer-readable recording medium"
The term is not limited to a portable recording medium such as a flexible disk or a CD-ROM, but includes an internal storage device in a computer such as various RAMs and ROMs, and an external storage device fixed to the computer such as a hard disk. I'm out.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a printing system as an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a printer.

FIG. 3 is a block diagram showing a configuration of a control circuit 40 in the color printer 20.

FIG. 4 is an explanatory diagram showing a nozzle array on the lower surface of the print head.

FIG. 5 is a flowchart showing a print processing procedure according to the first embodiment of the present invention.

FIG. 6 is a view showing an example of a print mode basic setting screen displayed on the CRT 21.

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 blur suppression processing for a contour portion according to the first embodiment of the present invention.

FIG. 9 is an explanatory diagram showing the flow of blurring suppression processing for the contour portion according to the first embodiment of the present invention.

FIG. 10 is an explanatory diagram showing a flow of a process of generating ink amount reduction data.

FIG. 11 is an explanatory diagram showing a calculation process used to generate ink amount reduction data.

FIG. 12 is a block diagram of a system that performs a blurring suppressing process for a contour portion according to the third embodiment of the present invention.

FIG. 13 is an explanatory diagram showing a flow of black area black dot data generation processing in the third embodiment of the present invention.

FIG. 14 is a block diagram of a system that performs a blurring suppressing process for a contour portion according to the 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 ... Operation 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 ... Contour line extraction unit 102 ... Ink amount reduction unit 103 ... Print mode selection section 104 ... Black determination unit 105 ... Dot data composition section

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Claims (19)

[Claims] 1. A print control apparatus for generating print data to be supplied to a print unit for performing printing by using a print unit that forms dots on a print medium while performing main scanning of a print head. A dot data generation unit that generates dot data indicating a dot formation state of each pixel in the print image according to the multi-tone image data that represents the color of each pixel of the print target image; A black determination unit that determines whether or not the color of each pixel is black, and that generates black region extraction data that represents a black region in which the pixel color is black according to the determination, and the black region extraction data According to the above, a contour line extraction unit that extracts a specific contour portion that is at least a part of the pixels that form the contour of the black area from the pixels that belong to the black area, and black ink in the specific contour portion. Formed by Print control apparatus and the ink amount reducer to adjust the dot data so as to reduce the amount of ink dots, characterized in that it comprises for. 2. The print control apparatus according to claim 1, wherein the black determination unit is data in which a color of a pixel belonging to the black area in the image data is replaced with a color other than black. A certain natural image area extraction data is generated, and the dot data generation unit is a black area black dot indicating a dot formation state in which each pixel belonging to the black area is filled with a black dot according to the black area extraction data. A black area black dot data generation unit that generates data, and a natural image area that generates black dot data that represents the formation state of black dots in each pixel by performing halftoning on the natural image area extraction data A black dot data generation unit, which combines the natural image area black dot data and the black area black dot data Print control apparatus comprising: a dot data combining unit, a generating dot data representing a state of formation of black dots in each pixel by. 3. The printing control device according to claim 1, wherein the printing unit includes a plurality of nozzles and a plurality of ejection drive elements for ejecting ink droplets from the plurality of nozzles. A print head capable of selectively forming any of N types (N is an integer of 2 or more) of different sizes in a region of one pixel on a print medium by using each nozzle, The print control apparatus, wherein the ink amount reduction unit reduces the ink amount by replacing a relatively large dot of the N types of dots with a relatively small dot. 4. The print control device according to claim 1, further comprising: a print mode selection allowing a user to select a print mode including a print resolution as a print mode parameter. The ink amount reduction unit, when the selected print resolution is less than a predetermined predetermined resolution, reduces the ink amount by replacing the dots, the selected print resolution is When the resolution is equal to or higher than the predetermined resolution, the print control apparatus reduces the ink amount by regularly thinning out some of the dots formed by the black ink in the specific contour portion. 5. The print control device according to claim 1, wherein the dot data generation unit includes a plurality of dots indicating which of the N types of dots is to be formed in each pixel. Dot data including bit data is generated, and the ink amount reduction unit replaces the dot by changing data of at least one bit of the plurality of bits in the pixel of the specific contour portion. A printing control device that reduces the amount of ink by. 6. The print control apparatus according to claim 1, further comprising a print mode including a type of print image having a text option as a print mode parameter for a user. A print control device comprising: a print mode selection unit that allows selection, wherein the ink amount reduction unit reduces the ink amount when the selection of the type of the print image is text. 7. The print control device according to claim 1, wherein the ink amount reduction unit reduces the ink amount only when the print medium is plain paper. apparatus. 8. The print control device according to claim 1, wherein the dot data includes color dot data representing a formation state of a color dot formed of color ink in each pixel. Print control device. 9. A print control apparatus for generating print data to be supplied to a printing unit for performing printing by using a printing unit that forms dots on a print medium while performing main scanning of a print head. A dot data generation unit that generates dot data indicating a dot formation state of each pixel in the print image according to the multi-tone image data that represents the color of each pixel of the print target image; A black determination unit that determines whether or not the color of each pixel is black, and generates black region extraction data that represents a black region in which the pixel color is black according to the determination, and according to the determination, A natural image region extraction data generation unit that generates natural image region extraction data, which 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 from black. Day The generation unit, in accordance with the black region extraction data, a black region black dot data generation unit that 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, A natural image region black dot data generation unit that generates a natural image region black dot data indicating a formation state of a black dot in each pixel by performing halftoning on the natural image region extraction data; And a dot data synthesizing unit for synthesizing the data and the black area black dot data to generate dot data representing a formation state of a black dot of each pixel. 10. A printing apparatus that performs printing using a printing unit that forms dots on a print medium while performing main scanning of a print head, wherein the printing unit and any one of claims 1 to 9. Print control device,
A printing device including. 11. A printing apparatus for performing printing by forming dots on a print medium while performing main scanning of a print head, the printing apparatus according to multi-tone image data representing a color of each pixel of an image to be printed. A dot data generation unit that generates dot data that represents the dot formation state of each pixel in the print image, and determines whether the color of each pixel is black according to the image data. A black determination unit that generates black region extraction data that represents a black region in which the pixel color is black, and, from the pixels that belong to the black region, according to the black region extraction data, the outline of the black region. A contour line extraction unit that extracts a specific contour portion that is at least a part of the pixels that form the dot data, and that reduces the ink amount of dots formed with black ink in the specific contour portion. And the ink amount reducer for integer, in response to said adjusted dot data, the printing apparatus characterized by comprising: a dot forming section for forming dots on the print medium. 12. A printing apparatus for performing printing by forming dots on a print medium while performing main scanning of a print head, the multi-gradation image data representing the color of each pixel of an image to be printed. A dot data generation unit that generates dot data that represents the dot formation state of each pixel in the print image, and determines whether the color of each pixel is black according to the image data. A black determination unit that generates black region extraction data that represents a black region in which the pixel color is black, and, in accordance with the determination, changes the color of the pixel belonging to the black region in the image data from black to other than black. A natural image region extraction data generation unit that generates natural image region extraction data that is data replaced with another color, wherein the dot data generation unit changes the black region to the black region according to the black region 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 is filled with a black dot, and each pixel by performing halfton processing on the natural image area extraction data , A natural image area black dot data generation unit that generates natural image area black dot data representing the formation state of the black dots, and by combining the natural image area black dot data and the black area black dot data A printing method, comprising: a dot data combining unit that generates dot data representing a black dot formation state; and a dot forming unit that forms dots on the print medium in accordance with the combined dot data. apparatus. 13. A printing method for performing printing by forming dots on a print medium while performing main scanning of a print head, comprising: (a) a multi-gradation image representing a color of each pixel of an image to be printed. Generating dot data representing a dot formation state of each pixel in the print image according to the data,
(B) determining whether each pixel has a black color according to the image data, and generating black region extraction data representing a black region having a black pixel color according to the determination And (c) extracting a specific contour portion, which is at least a part of the pixels forming the contour of the black area, from the pixels belonging to the black area according to the black area extraction data, d) adjusting the dot data so as to reduce the ink amount of dots formed by black ink in the specific contour portion, and (e) adjusting the dot data on the print medium according to the adjusted dot data. And a step of forming dots, the printing method comprising: 14. A printing method for performing printing by forming dots on a print medium while performing main scanning of a print head, comprising: (a) a multi-gradation image representing a color of each pixel of an image to be printed. A step of generating dot data representing a dot formation state of each pixel according to the data, and (b) determining whether or not the color of each pixel is black according to the image data, and the determination Generating black area extraction data representing a black area in which the color of the pixel is black, and (c) changing the color of the pixel belonging to the black area in the image data from black to other than black in accordance with the determination. A step of generating natural image region extraction data, which is data replaced with another color of
The step (a) includes (d) generating black area black dot data representing a dot formation state in which each pixel belonging to the black area is filled with a black dot in accordance with the black area extraction data. A step (e) performing halftoning on the natural image area extraction data to generate natural image area black dot data representing a black dot formation state in each pixel; and (f) the natural image area. Generating dot data representing a black dot formation state of each pixel by synthesizing the black dot data and the black area black dot data;
(G) forming dots on the print medium according to the combined dot data. 15. A print control method for generating print data to be supplied to a printing unit for performing printing by using a printing unit that forms dots on a print medium while performing main scanning of a print head. , (A) a step of generating dot data representing a dot formation state of each pixel in the print image in accordance with multi-tone image data representing a color of each pixel of the print target image, and (b) the image data Determining whether the color of each pixel is black in accordance with the above, and generating black region extraction data representing a black region in which the color of the pixel is black in accordance with the determination, (c) the above Depending on the black area extraction data,
A step of extracting a specific contour portion, which is at least a part of pixels forming the contour of the black area, from the pixels belonging to the black area; and (d) forming the specific contour portion with black ink. And a step of adjusting the dot data so as to reduce the ink amount of dots. 16. A print control method for generating print data to be supplied to a printing unit for performing printing by using a printing unit that forms dots on a printing medium while performing main scanning of a printing head. , (A) generating dot data representing a dot formation state of each pixel according to multi-tone image data representing the color of each pixel of the print target image, and (b) corresponding to the image data Determining the color of each pixel is black, and generating black region extraction data representing a black region in which the pixel color is black according to the determination,
(C) generating natural image region extraction data, which is data obtained by replacing the color of a pixel belonging to the black region with a color other than black in the image data, in accordance with the determination. The step (a) includes (d) a step of generating black area black dot data representing a dot formation state in which each pixel belonging to the black area is filled with a black dot according to the black area extraction data. (E) a step of generating halftone processing on the natural image area extraction data to generate natural image area black dot data representing a black dot formation state in each pixel, and (f) the natural image area black dot Generating dot data representing a black dot formation state of each pixel by synthesizing the data and the black area black dot data. A print control method comprising: 17. A computer program for causing a computer to generate print data to be supplied to the printing unit in order to perform printing using the printing unit that forms dots on the printing medium while performing main scanning of the printing head. The computer program is a dot data generation function for generating dot data representing a dot formation state of each pixel in a print image in accordance with multi-tone image data representing a color of each pixel of a print target image. And a black determination that determines whether the color of each pixel is black according to the image data and that generates black region extraction data that represents a black region in which the pixel color is black according to the determination. According to the function and the black region extraction data, a specific contour portion which is at least a part of pixels forming the contour of the black region is selected from the pixels belonging to the black region. A contour line extracting function to output, a computer program for realizing an ink reduction function to adjust the dot data so as to reduce the amount of ink dots formed by the black ink in the particular contour to the computer. 18. A computer program for causing a computer to generate print data to be supplied to the printing unit in order to perform printing by using a printing unit that forms dots on a printing medium while performing main scanning of the printing head. The computer program is a dot data generation function for generating dot data representing a dot formation state of each pixel in a print image in accordance with multi-tone image data representing a color of each pixel of a print target image. And a black determination function that determines whether or not the color of each pixel is black according to the image data, and generates black region extraction data that represents a black region in which the color of the pixel is black according to the determination. According to the determination, a natural image area extraction is data in which the color of the pixel belonging to the black area in the image data is replaced with a color other than black And a program for causing the computer to realize a natural image area extraction data generation function for generating a data, and the dot data generation function, in accordance with the black area extraction data, sets each pixel belonging to the black area to a black dot. The black area black dot data generation function that generates black area black dot data that represents the dot formation state that is filled with, and the black dot formation state in each pixel by performing halfton processing on the natural image area extraction data And a natural image area black dot data generation function for generating natural image area black dot data, and by combining the natural image area black dot data and the black area black dot data Dot data composition function to generate the dot data No, the computer program. 19. A computer-readable recording medium in which the computer program according to claim 17 or 18 is recorded.