JP2004274649A - Printing capable of non-uniform resolution conversion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology of attaining a high image processing speed while suppressing deterioration in image quality. <P>SOLUTION: A print controller generates print data supplied to a print section capable of forming ink dots on a print medium in response to image data including at least a single color plane. The print controller composes parts of a plurality of pixels included in at least part of the plane included in the image data so as to nonuniformly convert the resolution of part of the plane and convert the part into multi-gradation data, and decreases the number of gradations of the multi-gradation data into the number of gradations at which the print section can reproduce the gradation data in response to the type and the gradation value of each pixel of the multi-gradation data. In the resolution conversion, the print controller selects a plurality of composite object pixels being composite objects, decides the propriety of composition depending on the magnitude of a difference between a minimum value and a maximum value of pixel values of a plurality of the selected pixels and composes the pixels whose composition is decided possible accordingly. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD 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 An ink jet printer that forms an ink dot on a print medium by ejecting ink droplets to print an image is widely used as an output device of an image created by a computer or the like. 2. Description of the Related Art In printing by an inkjet printer, in recent years, higher resolution has been promoted in order to improve image quality. On the other hand, a technique for performing color reduction processing in two stages as disclosed in Patent Document 1 has also been proposed.
[0003]
[Patent Document 1]
JP-A-11-254711
[Problems to be solved by the invention]
However, in recent years, the time required for image processing has been increasing with the increase in resolution, which has spurred the demand for technology for increasing the image processing speed.
[0005]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems in the related art, and has as its object to provide a technique for increasing the speed of image processing while suppressing deterioration in image quality.
[0006]
[Means for Solving the Problems and Their Functions and Effects]
In order to solve at least a part of the problems described above, the present invention provides a printing method for generating print data to be supplied to a printing unit capable of forming ink dots on a print medium in accordance with image data including at least one color plane. A control device,
A resolution conversion unit capable of non-uniformly converting the resolution of some of the planes by synthesizing a part of a plurality of pixels included in at least some of the planes included in the image data. When,
A color conversion unit configured to convert the image data subjected to the non-uniform resolution conversion into multi-gradation data representing gradation values of a plurality of ink colors available in the printing unit;
A color reduction unit that reduces the multi-tone data to the number of tones that the printing unit can reproduce, according to the type and tone value of each pixel of the multi-tone data;
With
The resolution converter,
A pixel selection unit that selects a plurality of synthesis target pixels to be synthesized,
A combination availability determination unit that determines availability of the combination according to the difference between the minimum value and the maximum value of the pixel values of the selected pixels in each plane;
According to the determination, a pixel synthesis unit that performs the synthesis only the plurality of synthesis target pixels determined that the synthesis is possible,
It is characterized by having.
[0007]
The present invention is configured based on the following situation. That is, depending on the properties of the image to be printed, there are cases where the improvement in image quality due to the increase in resolution is noticeable and cases where it is not noticeable. For example, an image region in which the color rapidly changes has a remarkable improvement in image quality due to the high resolution, whereas an image region in which the color changes slowly has the property that the image quality does not improve much even if the resolution increases.
[0008]
According to the print control apparatus of the present invention, whether or not combination is possible is determined according to the magnitude of the difference between the minimum value and the maximum value of the pixel values of a plurality of pixels to be combined, and it is determined that combination is possible. Can be combined only if Generally, image quality degradation is small even when pixels with small pixel value differences are combined, but image quality degradation is large when pixels with large pixel value differences are combined. Pixel synthesis processing can be selectively performed. As a result, it is possible to increase the speed of the image processing while suppressing the deterioration of the image quality.
[0009]
In the above-described print control device, the color reduction section may select one of a plurality of ink dot patterns prepared in advance according to the type and gradation value of each pixel of the multi-gradation data. The selection may reduce the multi-gradation data to the number of gradations that can be reproduced by the printing unit.
[0010]
In the print control apparatus, the image data includes an R plane representing an R component value, a B plane representing a B component value, and a G plane representing a G component value. Determines whether the difference between the minimum value and the maximum value of the pixel values of the plurality of selected pixels is equal to or less than a predetermined value for each plane, and determines that the difference is equal to or less than the predetermined value in all the planes. If determined, it may be determined that the combination is possible,
The image data includes a lightness plane representing a value of a component having a relatively high brightness and a correlation, and a hue plane representing a value of a component having a relatively high hue and a high correlation. Determine whether the difference between the minimum value and the maximum value of the pixel values of the selected pixels in the brightness plane is equal to or less than a predetermined value, and when it is determined that the difference is equal to or less than the predetermined value, It may be determined that combination is possible.
[0011]
Here, the brightness plane representing the value of the component having a relatively high correlation with the brightness means, for example, a Y plane representing the luminance when the image data is image data of the YCbCr color system. The reason for judging the possibility of combining using only the lightness plane is to consider that human eyes are more sensitive to the lightness resolution than the hue. The image data including a lightness plane representing the value of a component having a relatively high correlation with lightness and a hue plane representing a value of a component having a relatively high correlation with hue include, for example, a Lab color system or L * u *. There is also image data of a color system such as the v * color system.
[0012]
In the print control apparatus, the image data is the pitch in the sub-scanning direction pitch in the main scanning direction is an M ₁ is composed of pixels N _1,
Image data to which the resolution conversion is made, the pitch in the sub-scanning direction pitch in the main scanning direction is a M ₂ is includes a pixel of the N _2,
M ₂ is M ₁ · R _M (R _M is a natural number);
The N ₂ is N ₁ · _RN ( _RN is a natural number),
At least one of the R _M and the R _N may also be is an integer of 2 or more.
[0013]
In the print control device, the image data includes three planes,
The number of the plurality of ink colors may be four or more.
[0014]
Since multi-gradation data including planes of the number of ink colors is generated, the present invention has a remarkable effect when the number of ink colors available in the printer is larger than the number of planes to be subjected to resolution conversion. To play.
(1) The case where the number of ink colors is four is a case where, for example, cyan ink, magenta ink, yellow ink, and black ink can be used.
(2) The case where the number of ink colors is six is a case where, for example, two colors of light cyan ink and light magenta ink are used in addition to the above four ink colors. Here, the light cyan ink refers to a cyan ink having a lower density than the cyan ink, and the light magenta ink refers to a magenta ink having a lower density than the magenta ink.
(3) The case where the number of ink colors is seven is a case where, for example, a light black ink or a dark yellow ink is used in addition to the above six ink colors, for example. Here, the light black ink refers to an ink having a higher brightness than the black ink, and the dark yellow ink refers to an ink having a lower brightness than the yellow ink.
[0015]
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 resolution conversion apparatus, and a method for realizing the functions of those methods or apparatuses. The present invention can be realized in the form of a computer program, a recording medium on which the computer program is recorded, a data signal including the computer program, and embodied in a carrier wave.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in the following order based on examples.
A. Equipment configuration:
B. Printing process in an embodiment of the present invention:
C. Modification:
[0017]
A. Equipment configuration:
FIG. 1 is a block diagram illustrating a configuration of a printing system as one embodiment of the present invention. This printing system includes a computer 90 as a print control device and a color printer 20 as a printing unit. Note that the combination of the color printer 20 and the computer 90 can be called a “printing device” in a broad sense.
[0018]
In the computer 90, 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.
[0019]
When the application program 95 issues a print command, the printer driver 96 of the computer 90 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, the printer driver 96 includes a resolution conversion module 97, a color conversion module 98, a color reduction module 99, a print data generation module 100, and a color conversion table LUT. I have. Note that the resolution conversion module 97 includes an outline area extraction unit 101.
[0020]
The resolution conversion module 97 plays a role of converting the resolution (that is, the number of pixels per unit length) of the RGB image data received from the application program 95 into a predetermined resolution. The details of the resolution conversion will be described later.
[0021]
The color conversion module 98 converts the RGB image data into multi-gradation data representing gradation values 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. The color-converted multi-tone data has, for example, 256 tone values. The color reduction module 99 executes a color reduction process for expressing this gradation value with the number of gradations that can be realized by the color printer 20 using the density pattern method.
[0022]
The color reduction data generated by the color reduction processing is rearranged by the print data generation module 100 in the order of data to be transferred to the color printer 20, and output as final print data PD. Note that the print data PD includes raster data indicating a dot recording state during each main scan and data indicating a sub-scan feed amount.
[0023]
Note that the printer driver 96 corresponds to a program for realizing a function of 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. Examples of such a recording medium include a flexible disk, a CD-ROM, a magneto-optical disk, an IC card, a ROM cartridge, a punched card, a printed matter on which a code such as a bar code is printed, and a computer internal storage device (such as a RAM or ROM). Various computer readable media, such as memory and external storage, can be used.
[0024]
FIG. 2 is a schematic configuration diagram of the color printer 20. The color printer 20 includes a sub-scanning feed mechanism that conveys the printing paper P in the sub-scanning direction by a paper feed motor 22 and a main scanning feed that reciprocates the carriage 30 in the axial direction (main scanning 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 a paper feed motor 22 and a carriage motor 24, a control circuit 40 for controlling the exchange of signals with the print head unit 60 and the operation panel 32. The control circuit 40 is connected to the computer 90 via the connector 56.
[0025]
The sub-scanning feed mechanism that transports the print 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). A main scanning feed mechanism for reciprocating the carriage 30 includes an endless drive belt 36 provided between the carriage motor 24 and a slide shaft 34 laid parallel to the axis of the platen 26 and slidably holding the carriage 30. And a position sensor 39 for detecting the origin position of the carriage 30.
[0026]
In the color printer 20 having the above-described hardware configuration, the carriage 30 is reciprocated by the carriage motor 24 while the paper P is being conveyed by the paper feed motor 22, and at the same time, the piezo elements of the print head 28 are driven and Drops are ejected to form ink dots to form a multi-color and multi-tone image on the paper P.
[0027]
B. Printing process in an embodiment of the present invention:
FIG. 3 is a flowchart illustrating a print processing procedure according to the embodiment of the present invention. In step S110, the resolution conversion module 97 (FIG. 1) performs a first resolution adjustment process on the given RGB data. The first resolution adjustment process is a process for converting the resolution of the RGB data into a predetermined uniform resolution.
[0028]
FIG. 4 is an explanatory diagram showing the contents of the RGB data after the first resolution adjustment processing has been performed. This RGB data is composed of an R plane representing the value of the R component, a B plane representing the value of the B component, and a G plane representing the value of the G component. Each plane is composed of pixels of a uniform size (720 dpi × 720 dpi). The size of this pixel is determined in advance so that printing can be performed with a combination of a dot pitch that can be formed by the printer 20 and a dot pattern described later.
[0029]
FIG. 5 is an explanatory diagram illustrating an example of the R plane. In this R plane, as can be seen from this figure, the difference between the pixel values of the two pixels adjacent to the pixel in column C, row 1 and the pixel in row D, row 1 is 131. On the other hand, in this embodiment, when the difference between the pixel values of the adjacent pixels is 100 or more, it is assumed that there is a contour line whose color rapidly changes between these adjacent pixels. As a result, it can be seen that the dotted line between the pixel in column C, row 1 and the pixel in row D, row 1 is determined to have an outline. Similarly, it can be seen that all of the dotted lines are determined to be contour lines with rapidly changing colors.
[0030]
In step S120, the contour area extraction unit 101 included in the resolution conversion module 97 extracts a pixel synthesis target area including a contour line. The pixel synthesis target area means an area in which four pixels to be synthesized exist in the present embodiment, and for example, an A column 1 row, an A column 2 row, a B column 1 row, and a B column 2 row in FIG. An area where four pixels exist is one of the pixel synthesis target areas.
[0031]
FIG. 6 is an explanatory diagram illustrating a contour plane indicating whether each pixel synthesis target region includes a contour line. Each square area in FIG. 6 indicates a pixel synthesis target area, and has an area value. For example, the area value of the pixel synthesis target area (FIG. 6) in which four pixels (FIG. 5) in column A 1 row, row A column 2 row, row B column 1 and row B column 2 shown in FIG. It is "0".
[0032]
The area value indicates whether each pixel synthesis target area includes an outline. Specifically, when the area value is “1”, it indicates that the area includes an outline, and when the area value is “0”, the area does not include an outline. Is represented.
[0033]
In this embodiment, each area value is determined according to the difference between the maximum value and the minimum value of the pixel values of four pixels (FIG. 5) of each plane existing in the pixel synthesis target area. Specifically, each area value is determined based on the following criteria.
(1) The region value is determined to be “1” when the difference between the maximum value and the minimum value of the pixel values is at least a predetermined value (for example, 100) in at least one of the RGB planes. .
(2) The region value is determined to be “0” when the difference between the maximum value and the minimum value of the pixel value is less than a predetermined value (for example, 100) in all of the RGB planes.
[0034]
In this manner, a pixel synthesis target area including an outline in any of the RGB color components is extracted as an area having an area value of “1”. In this embodiment, for the sake of simplicity, it is assumed that the G plane and the B plane do not have an outline, but the R plane has an outline.
[0035]
In step S130, the resolution conversion module 97 performs a second resolution adjustment process. The second resolution adjustment process is a process of partially adjusting the resolution in order to reduce the number of pixels and increase the processing speed. The partial adjustment of the resolution is performed by synthesizing only four pixels existing in the pixel synthesis target area (area where the color changes gradually) whose area value is “0”.
[0036]
FIG. 7 is an explanatory diagram showing the R plane after the second resolution adjustment processing has been performed in the embodiment of the present invention. This R plane is obtained by non-uniform resolution conversion by synthesizing a part of a plurality of pixels with respect to an R plane (FIG. 5) having pixels of the same size. The R plane on which the second resolution adjustment processing has been performed has pixels of two sizes, that is, pixels of a size of 720 dpi × 720 dpi and pixels of a size of 360 dpi × 360 dpi.
[0037]
The pixel value of each pixel is determined as follows.
(1) A pixel having a size of 720 dpi × 720 dpi has the same pixel value as the pixel value before the second resolution adjustment processing.
(2) A pixel having a size of 360 dpi × 360 dpi has the same pixel value as an average value (fraction is rounded) of four pixel values before the second resolution adjustment processing.
[0038]
For example, the pixel value of the first row of column C after the second resolution adjustment processing is “54” as shown in FIG. 7, which is the same as the pixel value “54” (FIG. 5) before the second resolution adjustment processing. Pixel values. On the other hand, as shown in FIG. 7, the pixel value of the pixel in the area of the first and second rows A and B after the second resolution adjustment processing is “51”, and the four pixel values before the second resolution adjustment processing Average value (below the decimal point) of the pixel values “50” (column A, first row) “50” (column A, second row) “50” (column B, first row) “54” (column B, second row) of the pixel (FIG. 5) Has the same pixel value as (rounded off).
[0039]
By executing such processing on other planes (G plane and B plane), the second resolution adjustment processing (non-uniform resolution processing) of RGB data is completed. Since the number of pixels to be processed is reduced by such processing, it can be seen that the load of the subsequent image processing and the required size of the memory area are reduced. Specifically, in this example, the number of pixels is reduced from 36 to 15 for each plane by non-uniform resolution processing.
[0040]
In step S140, the color conversion module 98 converts the RGB image data subjected to the non-uniform resolution processing into multi-gradation data representing gradation values of a plurality of ink colors available to the color printer 20 for each pixel. Convert to
[0041]
FIG. 8 is an explanatory diagram showing the contents of the multi-tone data generated in this manner. The multi-tone data has four planes which are data of four colors, cyan (C), magenta (M), yellow (Y), and black (K). The plane of each color is data of 256 gradations in which each pixel has a size of 720 dpi × 720 dpi or 360 dpi × 360 dpi. Here, cyan (C), magenta (M), yellow (Y), and black (K) are ink colors that can be used in the printer 20. Further, it means that the density of the ink dots is higher as the gradation value is larger. The ink dot density means the ratio of the area of the ink dot to the unit area on the print medium.
[0042]
It can be seen that the number of pixels has been reduced from 144 (36 pixels × 4 planes) to 60 (15 pixels × 4 planes) by the non-uniform resolution processing.
[0043]
In step S150, the color reduction module 99 performs a color reduction process. The color reduction processing is performed by selecting a dot pattern from the contour dot patterns according to the pixel values of the multi-tone plane.
[0044]
FIG. 9 is an explanatory diagram showing a part of the dot pattern used for the color reduction processing. This figure shows a dot pattern used for each pixel having a size of 720 dpi × 720 dpi. In each of these dot patterns, dots are arranged at a pitch of 2880 dpi. These dot patterns include a plurality of dot formation positions corresponding to one pixel of a pixel having a size of 720 dpi × 720 dpi of multi-tone data, and dot formation at a plurality of (16) dot formation positions is performed. Is determined according to multi-tone data for one pixel.
[0045]
FIG. 10 is an explanatory diagram showing the relationship between the gradation value of the multi-gradation data and the dot pattern. The dot pattern numbers correspond to the dot pattern numbers in FIG. For example, when the gradation value is 160, the 10th dot pattern is selected. When the gradation value is 0 to 15, the 0th dot pattern not shown in FIG. 9 is selected. The number 0 dot pattern is a pattern in which no ink dots are formed.
[0046]
The color reduction module 99 further has a dot pattern (not shown) used for each pixel having a size of 360 dpi × 360 dpi. In these dot patterns, dots are similarly arranged at a pitch of 2880 dpi. These dot patterns include a plurality of (64) dot formation positions corresponding to one pixel of the multi-tone data having a size of 36 dpi × 360 dpi.
[0047]
When such processing is performed for all pixels of the plane of each color (C, M, Y, K), dot data representing the dot formation state at each dot formation position on the print medium is generated.
[0048]
FIG. 11 is an explanatory diagram illustrating an example of a dot formation state on a print medium. FIG. 11A shows a dot formation state in the embodiment of the present invention. That is, an example in which the number of pixels is reduced by non-uniform resolution processing is shown. On the other hand, FIG. 11B shows an example in which the number of pixels is not reduced by the non-uniform resolution processing. In FIG. 11A, the number of pixels is 15, whereas in FIG. 11B, the number of pixels is 36.
[0049]
As can be seen from FIG. 11, although the number of pixels has been reduced to 15 or less, the contour line where the color changes rapidly has not been lost and the position has not changed. Further, it can be seen from the comparison between the dot densities of the respective regions of FIGS. 11A and 11B that the difference is small. Thus, it can be seen that the non-uniform resolution processing suppresses the deterioration of the image quality despite the remarkable decrease in the number of pixels.
[0050]
FIG. 12 is an explanatory diagram illustrating another example of a dot formation state on a print medium. FIG. 12A is the same as FIG. 11A and shows an example in which the number of pixels is reduced by non-uniform resolution processing. On the other hand, FIG. 12B shows an example in which the number of pixels is reduced by uniform resolution processing. In FIG. 12A, the number of pixels is fifteen, whereas in FIG. 12B, the number of pixels is nine.
[0051]
As can be seen from FIG. 12, for example, it can be seen that the outline is blurred in the area of the C to D columns and the first and second rows. Further, comparing the dot densities of the respective regions in FIG. 11A and FIG. 11B, it can be seen that the difference is larger in the region of, for example, the first to second rows of columns C to D. As described above, it can be seen that the non-uniform resolution processing significantly reduces the deterioration of the image quality due to the decrease in the number of pixels as compared with the uniform resolution processing.
[0052]
The dot data generated in this manner is rearranged by the print data generation module 100 in the order of data to be transferred to the color printer 20, and output as print data PD (step S160 (FIG. 3)). The printer 20 executes printing according to the print data PD (step S170).
[0053]
As described above, in the present embodiment, the number of pixels is reduced by synthesizing only pixels having low image quality degradation even when they are synthesized, so that the image processing speed can be increased while suppressing image quality degradation. .
[0054]
C. Modification:
The present invention is not limited to the above-described examples and embodiments, but can be implemented in various modes without departing from the gist of the invention, and for example, the following modifications are possible.
[0055]
C-1. In the above embodiment, in the non-uniform resolution conversion, the resolution is converted in both the main scanning direction and the sub-scanning direction. For example, as shown in FIG. 13, the resolution is converted only in the main scanning direction. Alternatively, the resolution may be converted only in the sub-scanning direction.
[0056]
C-2. In the above embodiment, the color reduction processing is performed using the density pattern method. However, the color reduction processing may be performed using dither, for example. In general, the color reduction section used in the present invention is configured to reduce the multi-gradation data to the number of gradations that can be reproduced by the printing section according to the type and gradation value of each pixel of the multi-gradation data. It would be fine. When the color reduction processing is performed using dither, a dither pattern is used for each type of each pixel.
[0057]
C-3. In the above embodiment, the resolution of the RGB data is converted non-uniformly. However, it is also possible to convert the image data of the YCbCr color system non-uniformly. The present invention can be generally applied to image data including a brightness plane representing a value of a component having a relatively high correlation with lightness and a hue plane representing a value of a component having a relatively high correlation with hue. .
[0058]
Here, the brightness plane representing the value of the component having a relatively high correlation with the brightness means, for example, a Y plane representing the luminance when the image data is image data of the YCbCr color system. The image data including a lightness plane representing the value of a component having a relatively high correlation with lightness and a hue plane representing a value of a component having a relatively high correlation with hue include, for example, a Lab color system or L * u *. There is also image data of a color system such as the v * color system.
[0059]
In this case, it is determined whether the difference between the minimum value and the maximum value of the pixel values of the plurality of pixels selected in the brightness plane is equal to or less than a predetermined value, and is determined to be equal to or less than the predetermined value. In this case, it is preferable that the composition is determined to be possible when the combination is performed. Since the human eye is more sensitive to the lightness resolution than the hue, this has the advantage that it is possible to extract an area where the image quality is greatly degraded due to the combination only by judging whether or not one plane can be combined. .
[0060]
C-4. In the above embodiment, it is determined for each plane whether or not the difference between the minimum value and the maximum value of the pixel values of the plurality of pixels selected as the synthesis target is equal to or smaller than a predetermined value. Although it is determined that the composition is possible when it is determined that the value is equal to or less than the predetermined value, the possibility of the composition may be determined according to, for example, a value obtained by summing the differences in the respective planes. In general, the determination of whether or not to combine images according to the present invention is configured to determine whether or not combination is possible according to the magnitude of the difference between the minimum value and the maximum value of the pixel values of a plurality of pixels selected to be combined in each plane. It should be done.
[0061]
C-5. In the above embodiment, the resolution conversion is performed equally for all the planes included in the image data. However, for example, when a specific area of a specific plane does not include a contour line, only the area of the plane has pixels. May be synthesized. That is, non-uniform resolution conversion may be performed independently for each plane. The resolution conversion unit used in the present invention generally makes at least the resolution of the plane non-uniform by synthesizing a part of a plurality of pixels included in at least some of the planes included in the image data. Anything that can be converted may be used.
[0062]
C-6. In the above embodiment, non-uniform resolution conversion is performed using two types (two sizes) of pixels, but three or more types of pixels having different sizes and shapes may be used.
[0063]
C-7. In the above embodiment, the computer 90 generates the dot data. However, for example, the computer 90 may supply multi-gradation data to the printer 20, and the printer 20 may perform the contour area extraction processing and the color reduction processing. . As described above, a part or all of the functions of the printer driver 96 may be executed by the control circuit 40 in the printer 20.
[0064]
C-8. In the above-described embodiment and modified examples, the outline area is extracted by processing the RGB data and the YCbCr data, and the ink amount is reduced using the extracted outline area. However, the method of extracting the contour region is not limited to this. For example, when data defining an outline such as an outline font is used for printing, an outline region may be extracted according to outline data generated from the outline data.
[0065]
C-9. In the above embodiment, the ink colors available in the printing unit are four, but may be six, seven, or more, for example. Since multi-gradation data including the number of planes of the number of ink colors is generated, the present invention is remarkable when the number of ink colors usable in the printer is larger than the number of planes to be subjected to resolution conversion. Effect.
[0066]
The case where the number of ink colors is six is a case where, for example, two colors of light cyan ink and light magenta ink are used in addition to four ink colors of cyan, magenta, yellow, and black. Here, the light cyan ink refers to a cyan ink having a lower density than the cyan ink, and the light magenta ink refers to a magenta ink having a lower density than the magenta ink. On the other hand, the case where the number of ink colors is seven is a case where, for example, a light black ink or a dark yellow ink is used in addition to the six ink colors, for example. Here, the light black ink refers to an ink having a higher brightness than the black ink, and the dark yellow ink refers to an ink having a lower brightness than the yellow ink.
[0067]
C-10. The present invention is applicable not only to color printing but also to monochrome printing. The present invention can be generally applied to printing in which ink dots are formed on a print medium in accordance with image data including at least one color plane.
[0068]
C-11. In the above embodiment, a part of the configuration realized by hardware may be replaced by software, and conversely, a part of the configuration realized by software may be replaced by hardware.
[0069]
When some or all of the functions of the present invention are implemented 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 may be an internal storage device in a computer such as various RAMs or ROMs, a hard disk or the like. And an external storage device fixed to the computer.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a printing system as one embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a color printer 20.
FIG. 3 is a flowchart illustrating a print processing procedure according to the embodiment of the present invention.
FIG. 4 is an explanatory diagram showing the contents of RGB data after a first resolution adjustment process has been performed.
FIG. 5 is an explanatory diagram showing an example of an R plane.
FIG. 6 is an explanatory diagram showing a contour plane indicating whether each pixel synthesis target area includes a contour line.
FIG. 7 is an explanatory diagram showing an R plane after a second resolution adjustment process has been performed in the embodiment of the present invention.
FIG. 8 is an explanatory diagram showing the contents of multi-tone data.
FIG. 9 is an explanatory diagram showing a part of a dot pattern used for the color reduction processing.
FIG. 10 is an explanatory diagram showing a relationship between a gradation value of multi-gradation data and a dot pattern.
FIG. 11 is an explanatory diagram showing an example of a dot formation state on a print medium.
FIG. 12 is an explanatory diagram showing another example of a dot formation state on a print medium.
FIG. 13 is an explanatory diagram showing an example of a dot formation state in a modified example.
[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 56 Connector 60 Print head Unit 90 Computer 94 Video driver 95 Application program 96 Printer driver 97 Resolution conversion module 98 Color conversion module 99 Color reduction module 100 Print data generation module 101 Outline area extraction unit LUT Color conversion table

Claims (10)

A print control apparatus for generating print data to be supplied to a printing unit capable of forming ink dots on a print medium in accordance with image data including at least one color plane,
A resolution conversion unit capable of non-uniformly converting the resolution of some of the planes by synthesizing a part of a plurality of pixels included in at least some of the planes included in the image data. When,
A color conversion unit configured to convert the image data subjected to the non-uniform resolution conversion into multi-gradation data representing gradation values of a plurality of ink colors available in the printing unit;
A color reduction unit that reduces the multi-tone data to the number of tones that the printing unit can reproduce, according to the type and tone value of each pixel of the multi-tone data;
With
The resolution converter,
A pixel selection unit that selects a plurality of synthesis target pixels to be synthesized,
A combination availability determination unit that determines availability of the combination according to the difference between the minimum value and the maximum value of the pixel values of the selected pixels in each plane;
According to the determination, a pixel synthesis unit that performs the synthesis only the plurality of synthesis target pixels determined that the synthesis is possible,
A print control device, comprising: The print control device according to claim 1,
The color reduction unit selects one of a plurality of ink dot patterns prepared in advance according to the type and gradation value of each pixel of the multi-gradation data, thereby A print control device that reduces multi-tone data to a number of tones that can be reproduced by the printing unit. The print control device according to claim 1 or 2,
The image data includes an R plane representing an R component value, a B plane representing a B component value, and a G plane representing a G component value.
The combination availability determination unit determines whether the difference between the minimum value and the maximum value of the pixel values of the selected pixels is equal to or less than a predetermined value for each plane, and the predetermined A print control device that determines that the combination is possible when it is determined that the value is equal to or less than the value. The print control device according to claim 1 or 2,
The image data includes a brightness plane representing a value of a component having a relatively high correlation with lightness, and a hue plane representing a value of a component having a relatively high correlation with hue.
The combination availability determination unit determines whether a difference between a minimum value and a maximum value of pixel values of the selected pixels in the brightness plane is equal to or less than a predetermined value, and the difference is equal to or less than the predetermined value. A print control device that determines that the combination is possible when it is determined. The print control device according to any one of claims 1 to 4, wherein
The image data is the pitch in the sub-scanning direction pitch in the main scanning direction is an M ₁ is composed of pixels N _1,
Image data to which the resolution conversion is made, the pitch in the sub-scanning direction pitch in the main scanning direction is a M ₂ is includes a pixel of the N _2,
M ₂ is M ₁ · R _M (R _M is a natural number);
The N ₂ is N ₁ · _RN ( _RN is a natural number),
Wherein at least one of R _M and the R _N, is an integer of 2 or more, the print control apparatus. The print control device according to claim 1, wherein:
The image data includes three planes,
The print control device, wherein the number of the plurality of ink colors is four or more. A printing apparatus capable of forming ink dots on a print medium in accordance with image data including at least one color plane,
A resolution conversion unit capable of non-uniformly converting the resolution of some of the planes by synthesizing a part of a plurality of pixels included in at least some of the planes included in the image data. When,
A color conversion unit configured to convert the image data subjected to the non-uniform resolution conversion into multi-gradation data representing gradation values of a plurality of ink colors available in the printing unit;
A color reduction unit that reduces the multi-tone data to the number of tones that the printing unit can reproduce, according to the type and tone value of each pixel of the multi-tone data;
An ink dot forming unit that forms ink dots on a print medium according to the color-reduced data;
With
The resolution converter,
A pixel selection unit that selects a plurality of synthesis target pixels to be synthesized,
A combination availability determination unit that determines availability of the combination according to the difference between the minimum value and the maximum value of the pixel values of the selected pixels in each plane;
According to the determination, a pixel synthesis unit that performs the synthesis only the plurality of synthesis target pixels determined that the synthesis is possible,
A print control device, comprising: A printing method capable of forming ink dots on a print medium according to image data including at least one color plane,
(A) non-uniformly converting the resolution of some of the planes by synthesizing a part of a plurality of pixels included in at least some of the planes included in the image data;
(B) converting the image data subjected to the non-uniform resolution conversion into multi-gradation data representing gradation values of a plurality of ink colors usable in the printing unit;
(C) reducing the multi-gradation data to a number of gradations that can be reproduced by the printing unit according to the type and gradation value of each pixel of the multi-gradation data;
(D) forming ink dots on a print medium according to the color-reduced data;
With
The step (a) comprises:
(A-1) selecting a plurality of synthesis target pixels to be synthesized;
(A-2) a step of determining whether or not to perform the combination according to the magnitude of the difference between the minimum value and the maximum value of the pixel values of the selected pixels in each plane;
(A-3) performing the combination only on the plurality of combination target pixels for which the combination is determined to be possible according to the determination;
A printing method, comprising: A resolution conversion device capable of non-uniformly converting the resolution of image data including at least one color plane,
A pixel combining unit that combines a part of a plurality of pixels included in at least some of the planes included in the image data;
A pixel selection unit that selects a plurality of synthesis target pixels to be synthesized,
A combination availability determination unit that determines availability of the combination according to the difference between the minimum value and the maximum value of the pixel values of the selected pixels in each plane;
With
The resolution conversion device, wherein the pixel combining unit performs the combining only on the plurality of combining target pixels determined to be capable of the combining according to the determination. In order to perform printing using a printing unit capable of forming ink dots on a printing medium in accordance with image data including at least one color plane, the computer generates print data to be supplied to the printing unit. A computer program,
A function of non-uniformly converting the resolution of the some planes by synthesizing a part of a plurality of pixels included in at least some planes among the planes included in the image data;
A function of converting the image data subjected to the non-uniform resolution conversion into multi-gradation data representing gradation values of a plurality of ink colors available in the printing unit;
A function of reducing the multi-gradation data to a number of gradations that can be reproduced by the printing unit according to the type and gradation value of each pixel of the multi-gradation data;
Including a program that causes the computer to implement,
The function of converting the resolution non-uniformly includes:
A function of determining whether or not to perform the combination according to the magnitude of the difference between the minimum value and the maximum value of the pixel values of the selected pixels in each of the planes;
According to the determination, a function of performing the synthesis only the plurality of synthesis target pixels determined that the synthesis is possible,
A computer program characterized by including:

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