JP4921254B2 - Image processing apparatus, image processing method, control program, and recording medium - Google Patents

Description

  The present invention relates to an image processing apparatus, an image processing method, a control program, and a recording medium, and particularly executes image formation using a chromatic color developer and an achromatic color developer that represent a partial range of the entire hue range. It relates to the image processing.

In recent years, there has been a tendency to digitize information, and image processing apparatuses such as printers and facsimiles used for outputting digitized information and scanners used for digitizing documents have become indispensable devices. Such an image processing apparatus is often configured as a multifunction machine that can be used as a printer, a facsimile, a scanner, or a copier by providing an imaging function, an image forming function, a communication function, and the like. In an image forming apparatus capable of outputting full color, a method has been proposed in which image formation is executed with gray scale (monochrome) and one predetermined basic color instead of full color (see, for example, Patent Document 1). In the method described in Patent Document 1, for input image data, colors included in a predetermined hue range are output in a predetermined basic color, and colors in other hue ranges are output in gray scale. . Also, by converting the color difference in the hue direction into the color difference in the saturation direction, various color expressions can be made with only one predetermined basic color and gray scale.
JP 2005-328276 A

  In the method described in Patent Document 1, the difference in color between the hue direction and the saturation direction is considered, but the difference in color in the lightness direction, particularly in the direction approaching black, is not considered. That is, when the basic color + grayscale printing is executed using the method described in Patent Document 1, it is not possible to represent a color that is close to black from the basic color (a color with reduced brightness). Therefore, when outputting such a color, printing is performed using a color that should not be used, and the ink use suppression effect, which is a merit of printing of basic color + gray scale, cannot be obtained.

  Here, the said subject is demonstrated in detail using FIG. 11 (a), (b). FIGS. 11A and 11B are diagrams showing RGB (Red-Green-Blue) and CMYK (Cyan-Magenta-Yellow-blackK) values when the brightness is lowered by bringing red closer to black. . FIG. 11A shows the RGB values and the complementary CMYK values when red is brought close to black. When it is completely red as shown in FIG. 11A, the RGB value is (255, 0, 0), and the corresponding CMYK value is (0, 255, 255, 0). In this case, the inks required for output are M and Y inks, and can be output without using C ink. When the state approaches black from this state, the RGB value in the middle is (128, 0, 0), and the corresponding CMYK value is (128, 255, 255, 0). Furthermore, when it becomes completely black, the RGB value is (0, 0, 0), and the CMYK value is (255, 255, 255, 0).

  Here, in the color conversion from RGB to CMYK, the adjustment is not actually performed as shown in FIG. 11A, and as K approaches red from black, the value of K is added to CMYK and other colors (above) In this example, the adjustment is made to subtract M and Y). FIG. 11B is a diagram illustrating one mode. As shown in FIG. 11B, when the RGB value is (128, 0, 0) in an intermediate color between red and black, the corresponding CMYK values are adjusted to (128, 155, 155, 100). . Further, when the RGB value is (0, 0, 0) in the complete black color, the corresponding CMYK values are (128, 128, 128, 255). Here, the reason why the CMYK values are not set to (0, 0, 0, 255) in the complete black is because it is necessary to maintain the continuity of colors. As shown in FIGS. 11A and 11B, when the complete red (255, 0, 0) is expressed, it can be expressed by M and Y without using C. It is possible to obtain the effect. However, when expressing a color close to black from the basic color, that is, a low brightness color (128, 0, 0), a color that should not be used (C in FIGS. 11A and 11B) is not used. It will be used, and the effect of suppressing the amount of ink used cannot be obtained.

  The present invention has been made in consideration of the above-described circumstances, and is used when image formation is performed using a chromatic color developer and an achromatic color developer that represent a partial range of the entire hue range. The purpose is to make it possible to express a color close to black.

In order to solve the above-described problem, the invention described in claim 1 is an image processing apparatus that processes image information for an image forming apparatus to execute image formation, and acquires the image information. And a drawing information generation unit that generates drawing information for causing the image forming apparatus to perform image formation based on the image information. The drawing information is generated when the image forming apparatus executes image formation. A plurality of chromatic color information related to the usage amount of a plurality of types of chromatic color developer to be used; and achromatic color information related to the usage amount of the achromatic color developer used when the image forming apparatus executes image formation; Non-use chromatic color information indicating that at least one of the plurality of chromatic color developers is not used, and the drawing information generation unit displays the image information with brightness, saturation, and hue. Convert to the format you have as a parameter And generating the achromatic information based on the parameters of the brightness.

  In the image processing apparatus according to claim 1, the drawing information generation unit includes at least one of the plurality of types of chromatic color developers as the unused chromatic color information. It is characterized in that information for generating zero developer is generated.

  According to a third aspect of the present invention, in the image processing apparatus according to the first aspect, the drawing information generation unit uses the plurality of types of chromatic color development in the image forming apparatus as the unused chromatic color information. Information for generating non-driving an image forming mechanism using at least one developer among the agents is generated.

According to a fourth aspect of the present invention, in the image processing apparatus according to any one of the first to third aspects, the drawing information generation unit is not used among the plurality of chromatic color developers. The chromatic color information corresponding to the chromatic color developer other than the chromatic color developer is generated based on the lightness parameter.

The invention described in Claim 5, in the image processing apparatus according to any one of claims 1 to 4, the image information generation unit which generates the image information based on the information of the input original image The original image information is information indicating the original image with parameters of three primary colors, the drawing information is information indicating the original image with parameters of three complementary colors, and the unused chromatic color information is , Information indicating that at least one of the three complementary color parameters and a component of the complementary color is zero, the image information generation unit is a hue to be output in a chromatic color when executing the image formation in particular for converting the chromatic color range determining unit for determining a chromatic range of hue range on the ring, the pixels other than pixels included in the chromatic range in pixels constituting the original image to grayscale Ri, achromatic pixel conversion information of the original image shown by the parameters of the three primary colors to produce a color parameter of the said unused chromatic information when it is converted into the rendering information indicated by the three complementary color parameters And the chromatic color range determination unit determines the chromatic color range based on the colors of the pixels constituting the original image.

The invention according to claim 6 is the image processing apparatus according to claim 5 , wherein the chromatic color range determination unit plots the hue of the pixels constituting the original image on a hue circle, and The chromatic color range is determined based on a distribution of plots.

According to a seventh aspect of the present invention, in the image processing device according to the sixth aspect , the chromatic color range determining unit plots the hue of pixels constituting a part of the original image on a hue circle. The chromatic color range is determined based on the distribution of the plot.

According to an eighth aspect of the present invention, in the image processing device according to any one of the fifth to seventh aspects, the chromatic color pixels included in the chromatic color range among the pixels constituting the original image are attached. The image processing apparatus further includes a color determining unit that determines a power color, and a chromatic color pixel converting unit that converts the hue of the chromatic pixel into an output hue based on the determined color.

The invention according to claim 9 is the image processing apparatus according to claim 8 , wherein the color determining unit plots the hue of the pixels constituting the original image on a hue circle. A color to be assigned to the chromatic color pixel is determined based on the distribution.

The invention according to claim 1 0, the image forming apparatus is an image processing method for processing image information for executing the image formation, acquires the image information, the image forming apparatus is an image forming Generating a plurality of chromatic color information related to the usage amount of a plurality of types of chromatic color developers used in execution based on the image information, and not using at least one of the plurality of chromatic color developers Is generated based on the image information, the image information is converted into a format having brightness, saturation, and hue as parameters, and the image forming apparatus executes image formation. Achromatic color information related to the amount of achromatic developer used at the time is generated based on the lightness parameter.

The invention of claim 1 1, a control program of an image processing apparatus, characterized in that it is executed by the image processing apparatus an image processing method according to claim 1 0.

The invention according to claim 1 2, a recording medium, wherein the image processing apparatus control program according to claim 1 1 recorded in a form readable.

  According to the present invention, when an image is formed using a chromatic color developer and an achromatic color developer that represent a partial range of the entire hue range, a color approaching black from the reference color can be expressed. It becomes possible.

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

  FIG. 1 is a block diagram illustrating an image processing apparatus 1 and an image forming apparatus 2 according to the present embodiment. As shown in FIG. 1, the image processing apparatus 1 includes a controller 100, a display 110 for visually displaying information, and a user interface 120 such as a keyboard and a mouse. As illustrated in FIG. 1, the image forming apparatus 2 includes a printer controller 201 and a printer engine 202. The controller 100 includes a main control unit 101, an application 102, a color profile 103, a printer driver 104, and a display driver 105. The controller 100 according to the present embodiment is configured by a combination of software and hardware. Specifically, a control program such as firmware stored in a nonvolatile recording medium such as a ROM (Read Only Memory), an EEPROM (Electronically Erasable and Programmable ROM), a HDD (Hard Disk Drive), or an optical disk is a DRAM (Dynamic). A controller 100 is configured by a software control unit and hardware such as an integrated circuit that are loaded into a volatile memory (hereinafter referred to as a memory) such as a random access memory (CPU) and configured under the control of a CPU (Central Processing Unit). The controller 100 functions as a control unit that controls the entire image processing apparatus 1.

  The main control unit 101 plays a role of controlling each unit included in the controller 100, and gives a command to each unit of the controller 100. In addition, the main control unit 101 transfers information input from the user via the user interface 120 to each unit of the controller 100. The application 102 is software having a function of browsing and editing image information stored in the image processing apparatus 1 and a function of generating image information under the control of the main control unit 111. The color profile 103 includes color setting information for correcting or converting the color of image information output according to the function, model, and the like of the display driver 105 and the image forming apparatus 2. The printer driver 104 is software that generates a print job based on image information received from the application 102 and transmits the print job to the printer controller of the image forming apparatus 2 under the control of the main control unit 101. The printer driver 104 refers to the color profile 103 when generating a print job, and generates a print job based on color settings corresponding to the image forming apparatus 2 that is the output destination.

  The display driver 105 drives the display 110 according to the control of the main control unit 101 and displays information on the display 110. The display driver 105 refers to the color profile 103 when driving the display 110 and drives the display 105 based on color setting information corresponding to the display 105. The printer controller 201 is a control unit that controls the operation of the image forming apparatus 2. Further, the printer controller 201 generates drawing information based on the image information received from the image processing apparatus 1. The printer engine 202 executes image formation on the printing paper under the control of the printer controller 201.

  Next, a flow of a general image forming operation (color print) by the image processing apparatus 1 and the image forming apparatus 2 according to the present embodiment will be described with reference to FIG. As shown in FIG. 2, when printing of image information being browsed by the application 102 is instructed (S201), the image information is input from the application 102 to the printer driver 104. Here, in the application 102, image information is processed as RGB (Red-Green-Blue) data, and the printer driver 104 receives the image information from the application 102 as RGB data. The printer driver 104 performs brightness, saturation, and hue adjustment on the RGB data received from the application 102 (S202). Also, the printer driver 104 refers to the color profile 103 and performs color matching processing of RGB data (S203). These processes in the printer driver 104 are executed mainly based on commands input from the user via the user interface 120.

  The printer driver 104 inputs the RGB data subjected to various adjustments and color matching to the printer controller 201 of the image forming apparatus 2 as a print job (S204). The printer controller 201 converts the RGB data received from the printer driver 104 into CMYK (Cyan-Magenta-Yellow-blackK) data that conforms to the amount of ink (developer) used by the printer engine 202 when executing image formation. (S205). In this conversion process, a known method such as BG / UCR (BLACK GENERATION / UNDER COLOR REMOVAL) or GCR (GRAY COMPONENT REPLACEMENT) can be used.

  Next, the printer controller 201 performs γ (gamma) conversion processing for adjusting color balance on the CMYK data generated by the conversion (S206). Further, the printer controller 201 performs gradation conversion of CMYK data in order to express gradation with a printer engine that cannot express gradation with multiple values (S207), and inputs the CMYK data to the printer engine 202 as drawing data. To do. In this gradation conversion, a known technique such as dithering or error diffusion can be used. Under the control of the printer controller 201, the printer engine 202 executes image formation based on the CMYK data received from the printer controller 201 by an electrophotographic method or an inkjet method (S208). As described above, the image forming operation according to the present embodiment is executed by the image processing apparatus 1 and the image forming apparatus 2, but part of the image processing for executing the image formation is executed by the printer controller 201. . That is, in this embodiment, the image forming apparatus 2 also partially operates as an image processing apparatus.

  In such an image processing apparatus 1, the present embodiment is characterized by the brightness, hue, and saturation adjustment processing in S202 and the CMYK data conversion processing in S205. In the lightness, hue, and saturation adjustment in this embodiment, full color data is converted into two-color data of one basic color and gray scale. In the CMYK data conversion in this embodiment, conversion is performed so that a low-lightness color (a color close to black from the basic color) originally expressed by the four colors of CMYK is expressed by the basic color and black. Specifically, in the past, when expressing red approaching black, MY was mixed with CK and expressed to be expressed with MY and K. The brightness, hue, and saturation adjustments according to this embodiment are executed in the image processing apparatus that is a computer in which the printer driver 104 program is installed as described above. Further, the CMYK data conversion according to the present embodiment is executed by the printer controller 201 of the image forming apparatus 2. Note that both brightness, hue, saturation adjustment, and CMYK data conversion may be executed by the image processing apparatus 1 or the image forming apparatus 2. Further, even when executing in the image processing apparatus 1, it may be executed by the application 102 or the printer driver 104.

  Next, brightness, hue, and saturation adjustment processing in the printer driver 104 according to the present embodiment will be described. FIG. 3 is a diagram visually displaying the relationship between lightness, saturation, and hue of a color. FIG. 4 is a diagram showing a hue circle. In FIG. 3, all colors are shown as a three-dimensional solid (color solid) of H (Hue: Hue), L (Limance: Lightness), and S (Saturation: Saturation). As shown in FIG. 3, the height direction of the solid indicates the lightness of the color. Lightness indicates the degree of brightness of a color, one end indicates white and the other end indicates black. The hue circle shown in FIG. 4 corresponds to a plane perpendicular to the L axis in the color solid of FIG. The circumferential direction (angular direction) of the circle shown in FIG. 4 indicates the hue, and the radial direction of the circle indicates the saturation in each hue. In the hue circle, the colors are distributed in a circular shape with the center being an achromatic color as the origin, and the color is more highly saturated as the distance from the center is increased. Each color is always distributed at a certain angle of the hue circle around the circumference (360 °), and the three primary colors R, G, and B are arranged so as to be inclined by 120 ° in the angular direction of the circle. In addition, Y, C, and M, which are intermediate colors of RGB colors, are arranged at intermediate positions (60 °).

  FIG. 5 is a flowchart illustrating the brightness, hue, and saturation adjustment processing described in S202 of FIG. The user designates one predetermined basic color as one process included in the brightness, hue, and saturation adjustment processes shown in S202 (S501). FIG. 6 is a diagram illustrating the hue range designation according to the present embodiment. In this embodiment, a case where R (red) is designated as the designated color for color printing will be described. Based on the basic color designated by the user, the printer driver 104 determines a hue range to be output with the designated basic color (S502). When the basic color designated in S501 is R, as shown in FIG. 6, there is a 120 ° angle range a centered on R on the hue circle, that is, a 120 ° range from M to Y. The specified output range. On the other hand, a range other than the determined range is set as a gray scale output range (S502). Based on the hue range determined in S502, the printer driver 104 adjusts the hue of the original image instructed to be printed by the application 102, and executes other brightness, saturation, and hue adjustments on the image (S503). .

  As a result of such processing, in S201 of FIG. 2, the color of the full-color image data instructed to be printed from the application 102 is converted into a color of red and gray scale. The color conversion according to this embodiment will be further described with reference to FIG. FIG. 7 is a diagram illustrating a full-color image that is instructed to be printed from the application 102. The full color image shown in FIG. 7 has a region b colored with a color included in the range a in FIG. 6 and a region c colored with other colors. Here, assuming that the color of the region b is a gradation from pink to white, the RGB values are each represented by 8 bits, and change from (255, 255, 255) to (255, 0, 255). If the color of the region c is a gradation from blue to white, the RGB value changes from (255, 255, 255) to (0, 0, 255). When the hue adjustment process shown in FIG. 2 and the hue adjustment process shown in FIG. 5 is executed on the image shown in FIG. 7, the color of the area b is included in the hue range a shown in FIG. The On the other hand, the color of the region c is not included in the hue range a shown in FIG.

  As a specific calculation example of hue conversion, for example, an RGB value is converted into an HLS value, and the hue value is changed after determining whether or not it is included in the hue range a based on the hue value. In the case of the area b, when the RGB value is converted into the HLS value shown in FIG. 3, the gradation of (H, L, S) = (60, 0.5, 0) to (60, 0.5, 1.0) Become. This indicates a line segment on the solid shown in FIG. 3 or on the hue circle shown in FIG. Specifically, on the hue circle shown in FIG. 4, when the angle of R is 0 °, an angle of 60 ° is shown. Further, the lightness L is 0.5, which is an intermediate point between the upper vertex of the color solid shown in FIG. 3 being 1 (white) and the lower vertex being 0 (black), and is a plane perpendicular to the L axis. = A line segment on the plane intersecting the L axis at the position of 0.5. The saturation S is a gradation from the lowest saturation to the maximum saturation, with 0 (minimum saturation or minimum density) on the L axis and 1.0 (maximum saturation or maximum density) of the outermost periphery of the solid. This is a line segment corresponding to the radius of the hue circle.

  Since the hue range a is 0 to 60 ° and 300 ° to 360 ° (or −60 ° to 60 °) when R is 0 ° as described above, the color of the region b is included in this range. Therefore, the hue H is converted to 0 ° which is red, the HLS values are changed to (0, 0.5, 0) to (0, 0.5, 1.0), and then converted to RGB again. 255, 255, 255) to (255, 0, 0).

  On the other hand, in the case of the region c, when the RGB value is converted into the HLS value, (120, 0.5, 0) to (120, 0.5, 1.0) are obtained. Since this is a color not included in the hue range a, it is converted to a gray scale. An existing method can be used as the grayscale conversion formula. For example, the converted grayscale value g is a value obtained by converting (normalizing) the RGB values 0 to 255 of the original image into 0 to 1 (R ', G', B ') can be obtained by the following equation (1).

  When the hue conversion is executed on the original image instructed to be printed from the application in this way, the image shown in FIG. 7 is converted into the red gradation in the area b and the gray scale in the area c.

  Next, the CMYK data conversion operation in the printer controller 201 according to this embodiment will be described. As described above, the image data input from the printer driver 104 to the printer controller 201 is input as RGB format data. Accordingly, the printer controller 201 converts image data input in RGB format into CMYK data. This is because the specification of a full-color image forming apparatus such as a general printer is designed to perform image formation based on CMYK values. In the case of the RGB format, white increases as each numerical value increases, whereas in the CMYK format, as the numerical value increases, the color approaches black. Therefore, the CMYK format uses more ink. This is because it is suitable for an actual image forming system in which full color is realized by mixing. In general, conversion from RGB data to CMYK data is performed by calculating respective complementary colors. The CMY values corresponding to the RGB values before conversion are obtained by the following equation (2), for example.

  That is, (255, 0, 0) indicating red as an RGB value becomes (0, 255, 255) when converted to a CMY value. This indicates that R is expressed by mixing M and Y inks. Generally, as described in FIG. 11B, which is a conventional example, when expressing low-lightness red (for example, a color having an RGB value of (128, 0, 0)), normal red Is expressed by adding C and K to M and Y that generate. Here, the gist of the image processing method according to the present embodiment is to express low brightness red with three colors of M, Y, and K. In other words, it is one of the gist to make it possible to express without using C even when expressing low brightness red. With reference to FIG. 8A, the CMYK conversion method according to the present embodiment will be described. Conversion from RGB to CMYK according to the present embodiment is executed according to the following equations (3) and (4).

  Expression (3) is an expression for simply calculating the complementary color (C′M′Y ′ data: three complementary colors) value based on the RGB data of the original image, and will be described with reference to FIG. Is equal to the state. The C′M′Y ′ data shown in Expression (3) is image information for the image forming apparatus 2 to execute image formation, and is generated by the printer controller 201. That is, in this case, the printer controller 201 functions as an image information acquisition unit. Expression (4) is an expression for further converting the C′M′Y ′ data obtained by Expression (3) to generate CMYK data. The CMYK data is drawing information that causes the printer controller 201 to cause the printer engine 202 to perform image formation, and is generated by the printer controller 201. That is, in this case, the printer controller 201 functions as a drawing information generation unit. In the CMYK data, C, M, and Y are chromatic color information related to chromatic ink usage, and K is achromatic information related to gray scale ink usage.

  In Equation (4), the lowest value among the C′M′Y ′ data values is set as the value of K. Further, the lowest value is subtracted from each value of C′M′Y ′. In this embodiment, since the output designated basic color is designated as red, the value of C ′ is lower than the values of M ′ and Y ′. That is, the lowest value among the C′M′Y ′ data values is the value of C ′. Accordingly, when CMY is calculated based on the C′M′Y ′ value, C becomes 0 at C′−C ′. That is, C is generated as unused chromatic color information based on C ′ which is the lowest value among the C′M′Y ′ data values. In other words, the amount of C developer used is zero. In addition, M and Y cannot express red that is close to black. However, the value obtained by subtracting from M and Y is set as the K value.

  FIG. 8A is a diagram showing RGB values and CMYK values converted using the CMYK conversion method according to the present embodiment when the brightness is lowered by bringing red closer to black. As shown in FIG. 8A, when red approaches black, the RGB value changes from (255, 0, 0) to (0, 0, 0). When this is converted into CMYK using the CMYK conversion method according to the present embodiment, in the state of (255, 0, 0), (0, 255, 255, 0) is obtained as in the conventional example shown in FIG. Become. When the brightness is slightly lower than red (200, 0, 0), C ′, which is a complementary color value of R, is 55. Therefore, 55 is subtracted from M and Y, and K is set to 55 (0, 200, 200, 55). As a result, it is possible to express red without using C, that is, with M, Y, and K, with reduced brightness. Thereafter, as the red color approaches black, the RGB R value decreases, so the C ′ value increases, the K value increases, and the M and Y values decrease. Then, in the state of being completely black, the CMYK value is (0, 0, 0, 255).

  Here, the C, M, and Y data will be further described. The position on the hue circle in FIG. 4, that is, the color, is determined in principle by two values of C, M, and Y and the ratio of the values. That is, in the case of a color between Y and M shown in FIG. 4, the values of Y and M and the ratio thereof are used. In the case of a color, the value is determined by the values of C and Y and the ratio thereof. The larger the two values, the higher the saturation color and the closer to the outer circumference of the hue circle. When the third color is mixed with these two values, the value mainly contributes to the lightness direction shown in FIG. 3 and the direction closer to black from the basic color (the color at the center of the L axis) (low lightness direction). To do. Whether each value of C, M, and Y is used as two values for determining the color or as one value mainly contributing to the brightness direction is determined by the magnitude of the value. The That is, when there are two or less non-zero values among C, M, and Y, one or two values are used as values for determining the color. On the other hand, when all three of C, M, and Y have non-zero values, the lowest of the three values is mainly used as a value that contributes to the low brightness direction, and the other two values mainly change the color. Used as a value to be determined. That is, in this embodiment, C ′ among C ′, M ′, and Y ′ is used as a low brightness parameter that mainly contributes to the low brightness direction.

  As described above, the CMYK conversion method according to the present embodiment is a case where an image drawn in RGB full color is drawn and printed in one of RGB basic colors and two gray scales in total. When RGB data is converted into CMYK data and image formation is performed, the complementary color (C in this embodiment) of the selected basic color is forcibly set as an unused color, and the unused value is set to the unused value. Accordingly, the values of the other basic colors (M and Y in this embodiment) are decreased and the value of K is increased. As a result, even when a low-lightness chromatic color is expressed, it is possible to express without using one of the CMY colors.

  In the above description, the example in which R is specified as the basic color to be output has been described. However, the present invention can be similarly applied even when B or G is specified. Even in such a case, it is possible to obtain the same effect as described above by applying the expressions (2) and (3) as they are. Specifically, when B is designated as the output target basic color, Y, which is the complementary color, is not used and is represented by C, M, and K.

  In the above description, as shown in FIG. 6, the example in which the color included in the hue range a from Y to M in the hue ring is output as R has been described. However, when two types of colors included in the hue range a in the original image and different colors (for example, orange and red) are adjacent to each other, both are converted to red. Then, the boundary may be indistinguishable. On the other hand, it is possible to prevent the boundary from becoming indeterminate even in the converted image by outputting the difference in the hue direction in the saturation direction or the brightness direction. As a method for converting the difference in hue direction into the difference in saturation direction, an existing method such as the method disclosed in Patent Document 1 can be used.

  On the other hand, consider a case where a difference in hue direction is converted into a difference in brightness direction. In the hue circle of RGB, when the hue shifts from the basic colors R, G, and B, for example, when approaching R or Y or M, the color looks lighter. This can be said to be because the color approaches white by adding G or B to R. Therefore, when converting the difference in the hue direction into the difference in the brightness direction, by increasing the brightness based on the displacement amount in the hue direction from the basic colors R, G, and B (angle H shown in FIGS. 3 and 4). It becomes possible to respond.

  In the above description, as shown in FIG. 6, the example in which the color included in the hue range a from Y to M in the hue ring is output as R has been described. However, since M and Y are finally used to express R, it is possible to express the difference in hue from M to Y by adjusting their ratio. Therefore, in the hue adjustment process shown in FIG. 5, the hues of the colors included in the hue range a are not all set to R, but can be any hue included in the hue range a. As a result, for example, when an original image with a lot of orange is converted using the CMYK conversion method according to the present embodiment, it is possible to output orange, so that after the conversion without impairing the ink usage reduction effect Can also be output with colors close to the original image.

  Further, since it is possible to express the difference in hue from M to Y by adjusting the ratio of M and Y, the hue of the chromatic color after conversion is not limited to R or one other hue, It is also possible to output the colors included in the range from M to Y as they are. For example, in the hue adjustment process illustrated in FIG. 5, the hues of colors included in the hue range a are input to the image forming apparatus 2 without adjustment. Since the color included in the hue range a has the largest value of R in RGB, when the CMYK conversion according to this embodiment is executed, C ′ becomes the smallest value and C becomes “0”. On the other hand, the values of M and Y are determined by the GB value of the original image, and the ratios thereof vary depending on where the target color is located in the hue range a. This makes it possible to express various colors without impairing the effect of reducing the amount of ink used (in the above embodiment, without using C). In the hue adjustment process shown in FIG. 5, in addition to outputting the colors included in the hue range a without adjustment, the RGB values are adjusted according to a predetermined color profile in order to correspond to the color expression in M and Y. Also good.

  In the above description, the output color is the basic color R, and the hue range a is 60 ° in the R to Y direction and 60 ° in the R to M direction. That is, the example in which the hue range a is set centering on the hue of the output color has been described. Thereby, the difference in hue before and after conversion of the color included in the chromatic range (hue range a) can be set to 60 ° or less on at least the hue circle shown in FIG. Therefore, it is possible to reduce the difference in hue in the image before conversion and after conversion, and to avoid color failure due to conversion. On the other hand, when the output color is R, the hue range a may be set to 60 ° in the vertical direction, for example, 30 ° in the Y direction (orange), 90 ° in the M direction (purple), or a total of 120 °. Alternatively, the hue range a may be wider than 120 ° or narrower. Such an example is effective when, for example, many of the colors of the original image that are desired to be chromatic are mainly distributed between orange and purple.

  In the above description, as illustrated in FIG. 6, the example in which the color included in the hue range a is output as the basic color R included in the hue range a has been described. In addition, the color included in the hue range a shown in FIG. 6 may be output as a color not included in the hue range a, such as B or G. In such a case, in the hue adjustment process shown in FIG. 5, the hue range of the output target color and the color target are individually designated. Thereafter, the hue in the hue range designated in the original image is converted in accordance with the output target color. For example, when outputting the color included in the hue range a shown in FIG. 6 as B, it can be realized by rotating the hue of the color included in the hue range a in the original image by 120 °. As a result, it is possible to adjust the color desired to be colored in the color of the original image and the color desired to reduce the amount of ink used in the image forming apparatus 2. For example, when the color to be colored is a color around R (for example, a color in the hue range from M to Y), the amount of ink used is usually C as described above. When it is desired to reduce the amount of ink used, this requirement can be met. Such designation is executed together with designation of the output target color in S201 in FIG.

  In the above description, as shown in FIG. 5, the user designates an output color (S501), and the hue range a to be colored by the printer driver 104 is determined based on the designated output color (S502). An example was explained. In addition, the user may designate a hue range a to be colored, and the printer driver 201 may determine an output color based on the designated hue range a. In such a case, if the above example is followed, the hue at the center angle of the designated hue range is set as the output color. Thereby, the colors of the original image and the converted image can be brought close to each other.

  In the above description, as shown in Expression (4), the smallest value Min (C ′, M ′, Y ′) of C ′, M ′, Y ′ is set to the value of K as it is, The example in which the value subtracted from the values of C ′, M ′, and Y ′ is also set to Min (C ′, M ′, Y ′) has been described. In addition, when determining a value to be subtracted from the K value and the C, M, and Y values, a value obtained by multiplying Min (C ′, M ′, Y ′) by a predetermined coefficient may be used. That is, as a generalized expression of Expression (4), coefficients for determining a value for subtracting the coefficient for determining the value of K from the values of F1, C ′, M ′, and Y ′ are F2, F3. And as F4, the following formula | equation (5) can be used.

  In Formula (5), when F1 to F4 are all set to 1, Formula (4) is obtained. In addition, when using equation (5), the coefficient of the value to be subtracted from the smallest value among at least C ′, M ′, and Y ′ is set to “1”. As a result, as in the case of Expression (4), any one value of CMY can be set to “0”.

  In the above description, CMYK is used as a color expression method for the printer controller 201 to drive the printer engine 202, and the printer controller 201 converts RGB data into CMYK data as ink usage amount determination means. explained. In addition, in addition to CMYK inks, LC (Light Cyan), LM (Light Magenta), and LY (Light Yellow) inks may be further used in order to improve color expression with low saturation. The present embodiment can also be applied to such a case. As an example of how to use C and LC, M and LM, and Y and LY, after converting from RGB to CMYK, if the values of C, M, and Y are low, use LC, LM, and LY to output the color. As the value increases, control is performed to mix C, M, and Y inks. Therefore, by applying the present embodiment as it is, when C is not used as described above, the C and LC inks are not used. In order to improve low brightness color expression and color continuity, any one of C and LC, M and LM, and Y and LY may be unused.

  In the above description, information to be subjected to image formation is input as RGB data, and the printer controller 201 calculates its complementary color to generate C ′, M ′, Y ′ data as image information. An example in which CMYK data is generated based on C ′, M ′, and Y ′ data has been described. In addition, for example, the printer controller 201 may generate HLS data based on the input original image information, and may generate CMYK data as drawing information based on the HLS data. In this case, since the color information is indicated by H, L, and S, L can be used as the low brightness parameter. In addition, information to be subjected to image formation may be indicated by a CMYK value (or CMY value), and the printer controller 201 may generate the drawing information based on the CMYK value (or CMY value).

  In the description of the first embodiment, the example in which the CMYK conversion is executed according to the above equation (4) has been described. In Expression (4), as the basic color approaches black, the ink amount (M and Y in FIG. 8A) representing the basic color is reduced and the black ink amount is increased. In the case of expressing complete black, it is expressed only by K without using any colors of C, M, and Y. In addition, in order to maintain color continuity, even when black is expressed, it can be used without reducing the values of M and Y. Such CMYK conversion can be realized by using, for example, the following equation (6).

  An example in which the CMYK conversion method of Expression (6) is applied is shown in FIG. As shown in FIG. 8B, when the CMYK conversion method according to the present embodiment is used, when the brightness decreases from red and approaches black, only the value of K in CMYK increases, and M and Y There is no change in the value of. Therefore, since the color change approaching black from red is expressed only by the change in the value of K, it is possible to maintain color continuity. In Expression (6), the case where C ′ is the smallest among C ′, M ′, and Y ′ is shown, but the same applies to the case where M ′ or Y ′ is the smallest.

  Further, even when the values of M and Y are decreased as red approaches black, after the values of M and Y are lowered to a predetermined value and then black is further increased, only the value of K is increased. It can also be expressed. Such CMYK conversion can be realized by using, for example, the following expression (7).

  An example in which the CMYK conversion method of Expression (7) is applied is shown in FIG. As shown in FIG. 8C, in the case of using the CMYK conversion method according to the present embodiment, when the brightness decreases from red and approaches black, after the values of M and Y decrease to 128, Only the values increase and the values of M and Y remain 128. Such an aspect also makes it possible to maintain color continuity and reduce the amount of ink used for M and Y. Further, since the overall ink use amount can be suppressed as compared with the case of Expression (7), the increase in the ink use amount can avoid the swell of the ink output on the paper surface. In Expression (7), the case where C ′ is the smallest among C ′, M ′, and Y ′ is shown, but the same applies to the case where M ′ or Y ′ is the smallest.

  In the case of using the CMYK conversion method of the equations (6), (7) and FIGS. 8 (b) and (c), when expressing complete black, the RGB data is (0, 0, 0), R, Since all the values of G and B are the same, Min (C ′, M ′, Y ′) shown in Expression (6) and Expression (7) cannot be determined. In such a case, the printer driver 104 notifies the printer controller 201 of a value that should be “0” among C, M, and Y, that is, Min (C ′, M ′, Y ′). As shown in FIG. 8B, it is possible to calculate (0, 128, 128, 255) as the CMYK value or (0, 255, 255, 255) as the CMYK value as shown in FIG. 8C. It becomes. In addition to the case where the printer driver 104 notifies the printer controller 201, the printer controller 201 analyzes the image data input from the printer driver 104, and “0” of C, M, and Y is determined based on the analysis result. The value to be taken may be obtained.

  In the first embodiment, the example in which the user designates the output target color and the chromatic range by designating one basic color (R in the first embodiment) has been described. In the present embodiment, an example will be described in which the printer driver 104 determines a color target range and an output target color based on information of an original image for which a print instruction has been issued by the application 102. In addition, about the structure which attaches | subjects the code | symbol similar to Example 1, the same or equivalent part as Example 1 is shown, and description is abbreviate | omitted.

  The brightness, color, and saturation adjustment processing according to this embodiment will be described with reference to FIG. FIG. 9 is a flowchart showing brightness, color, and saturation adjustment processing according to the present embodiment, and corresponds to FIG. 5 of the first embodiment. When the application 102 issues a print instruction for the original image data, the printer driver 104 reads the original image data and analyzes the color information of the image data (S901). The printer driver 104 determines a hue range (chromatic color range) to be colored based on the analysis result in S901 (S902). Thereafter, the printer driver 104 determines an output color based on the chromatic color range determined in S902 (S903). The printer driver 104 adjusts the hue of the original image instructed to be printed by the application 102 based on the chromatic color range determined in S902 and the output color determined in S903, and other brightness, Saturation and hue adjustment is executed (S904).

Next, an example of the original image data analysis in S901 and the chromatic color range determination method in S902 will be described. In the chromatic color range determination method according to the present embodiment, as shown in FIG. 10, the hue circle is divided into three ranges of hue ranges a ₁ , a ₂ , and a ₃ for determination. The printer driver 104 analyzes the original image data print instruction by the application 102, each pixel constituting the original image data to analyze belongs to any range of hue range a _1, a _2, a ₃ . As a result of the analysis, a range including the largest number of pixels in the hue ranges a ₁ , a ₂ , and a ₃ is determined as a chromatic color range. As a result, among the colors constituting the original image, the main colors can be chromatic colors and other colors can be achromatic colors, so while specifying a predetermined output color and reducing the amount of ink used, It is possible to generate a converted image with a color closer to the color of the original image.

A case where the CMYK conversion method according to the present embodiment is applied to the image shown in FIG. 7 will be described. The color of the region b of the image shown in FIG. 7 is mainly included in the hue range a ₂ shown in FIG. On the other hand, the color of the region c is included in the hue range a ₁ shown in FIG. When comparing the area b and the area c of the image shown in FIG. 7, the area c is obviously larger in area, so the printer driver 104 determines that the hue range a ₂ includes the most pixels. Therefore, when the image of FIG. 7 is converted by the CMYK conversion method according to the present embodiment, the region b is converted to gray scale and the region c is converted to blue gradation.

In the above description, as shown in FIG. 10, the hue circle is divided into three ranges a ₁ , a ₂ , and a ₃ , and which range includes each pixel constituting the original image. In this example, the range including the most pixels is determined as the chromatic color range. In addition, the pixels constituting the original image may be plotted on the hue circle first, and the chromatic color range may be determined based on the result of the plot. Such an embodiment is particularly effective when the original image includes many pixels having hues near the boundaries of a ₁ , a ₂ , and a _{3 in} the case shown in FIG. For example, consider a case in which the pixels constituting the original image are plotted on the hue circle, and as a result, a large number of plots are distributed around the boundary between the hue ranges a ₁ and a ₂ . In such a case, it is difficult to determine which of the hue ranges a ₁ and a ₂ is the chromatic color range. In such a case, for example, by setting the hue range from B to R as the chromatic color range and the output color as M, it is possible to generate a converted image with a color closer to the color of the original image.

  In the above description, an example in which the chromatic color range is determined based on all information of the original image has been described. However, by specifying a partial range of the original image and analyzing the pixels constituting the range, The chromatic color range may be determined. Such an embodiment is particularly effective in an image in which the background occupies a large proportion. That is, when the proportion of the background in an image showing a certain person or article is large, there is a high possibility that the chromatic color range is determined based on the background color when the above conversion method is used. In such a case, the person or article can be made a chromatic color by specifying the range in which the person or article is displayed in the image and analyzing the pixels. In the example of FIG. 7, when it is desired to make the region b chromatic and the region c to be achromatic, by specifying the region b and applying the CMYK conversion method according to this embodiment, the region b is provided. It can be colored.

  In the first embodiment, when CMYK conversion is executed, the printer driver 104 performs color conversion so that one of C, M, and Y is “0”, so that one of C, M, and Y is selected. An example in which image formation is executed without using the above has been described. In such an example, the C, M, and Y image forming mechanisms included in the printer engine 202 are not individually controlled, that is, even when all the C, M, and Y image forming mechanisms are driven. It is effective in that any one of them can be made unused. However, in such an example, when the printer controller 201 drives the printer engine 202, it also drives an image forming mechanism that does not need to print. On the other hand, the ink image forming mechanism determined to be unused among C, M, and Y may be controlled not to be driven (not driven).

  The implementation of such an aspect may be realized by the printer driver 104 notifying the printer controller 201 of the unused color after the unused color is determined and the hue adjustment is performed in the printer driver 104. it can. The printer controller 201 executes image formation without driving the image forming mechanism corresponding to the unused color notified from the printer driver 104 when performing image formation after performing CMYK conversion on the image. In addition, the unused color may be determined based on the image information received by the printer controller 201 from the printer driver 104. Such control can prevent the residual ink from being erroneously transferred to the paper surface when, for example, unused color ink remains on the transfer unit. In addition, power consumption can be reduced by reducing the drive portion.

1 is a block diagram illustrating an overall configuration of an image processing apparatus and an image forming apparatus according to an embodiment of the present invention. 5 is a flowchart illustrating an image forming operation according to the embodiment of the present invention. It is a figure which shows visually the lightness of color, the saturation, and the hue direction which concern on the Example of this invention. It is a figure which shows the hue ring which concerns on the Example of this invention. It is a flowchart which shows the brightness, the hue, and the saturation adjustment process which concerns on the Example of this invention. It is a figure which shows the chromatic color range designation | designated on the hue ring which concerns on the Example of this invention. It is a figure which shows the output target image which concerns on the Example of this invention. It is a figure which shows the RGB value which concerns on the Example of this invention, and another Example, and the CMYK value corresponding to it. It is a flowchart which shows the brightness, the hue, and the saturation adjustment process which concern on the other Example of this invention. It is a figure which shows hue range specification which concerns on the other Example of this invention. It is a figure which shows the RGB value which concerns on a prior art example, and the CMYK value corresponding to it.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image processing apparatus 2 Image forming apparatus 3,100 Controller 101 Main control part 102 Application 103 Color profile 104 Printer driver 105 Display driver 110 Display 120 User interface 201 Printer controller 202 Printer engine

Claims (12)

An image processing apparatus that processes image information for executing image formation by the image forming apparatus,
An image information acquisition unit for acquiring the image information;
A drawing information generation unit that generates drawing information for causing the image forming apparatus to perform image formation based on the image information;
The drawing information is
A plurality of pieces of chromatic color information related to the amount of use of a plurality of types of chromatic developer used when the image forming apparatus executes image formation;
Achromatic information related to the amount of achromatic developer used when the image forming apparatus executes image formation; and
Unused chromatic color information indicating that at least one of the plurality of chromatic color developers is not used,
The drawing information generation unit converts the image information into a format having brightness, saturation, and hue as parameters, and generates the achromatic color information based on the brightness parameter. .   The drawing information generation unit generates, as the unused chromatic color information, information that sets a usage amount of at least one developer among the plurality of types of chromatic developer to zero. Item 8. The image processing apparatus according to Item 1.   The drawing information generation unit generates, as the unused chromatic color information, information that non-drives an image forming mechanism that uses at least one of the plurality of types of chromatic color developer in the image forming apparatus. The image processing apparatus according to claim 1, wherein: The drawing information generation unit generates chromatic color information corresponding to the chromatic color developer other than the unused chromatic color developer among the plurality of chromatic color developers based on the lightness parameter. The image processing apparatus according to claim 1, wherein the image processing apparatus is an image processing apparatus. Further comprising an image information generation unit which generates the image information based on the information of the input original image,
The information of the original image is information indicating the original image by parameters of three primary colors,
The drawing information is information indicating the original image by three complementary parameters,
The unused chromatic color information is information indicating that at least one of the three complementary color parameters and a component of the complementary color is zero.
The image information generation unit
A chromatic color range determination unit that determines a chromatic range that is a hue range on a hue circle to be output in a chromatic color when executing the image formation;
By converting pixels other than the pixels included in the chromatic color range into grayscale in the pixels constituting the original image, the information of the original image indicated by the three primary color parameters is indicated by the three complementary color parameters. An achromatic color pixel conversion unit that generates a color parameter that becomes the unused chromatic color information when converted into drawing information ;
5. The image processing apparatus according to claim 1, wherein the chromatic color range determination unit determines the chromatic color range based on a color of a pixel constituting the original image. 6. 6. The chromatic color range determination unit determines the chromatic color range based on the distribution of the plot when the hues of pixels constituting the original image are plotted on a hue circle. An image processing apparatus according to 1. The chromatic color range determination unit determines the chromatic color range based on the distribution of the plot when the hues of pixels constituting a part of the original image are plotted on a hue circle , The image processing apparatus according to claim 6 . A color determination unit for determining a color to be attached to a chromatic color pixel included in the chromatic color range among the pixels constituting the original image;
And further comprising a chromatic color pixel converting unit for converting the hue for outputting hue of the chromatic color pixel based on the determined color, the image processing according to any one of claims 5 to 7 apparatus. The color determination unit determines a color to be attached to the chromatic color pixel based on the distribution of the plot when the hue of the pixel constituting the original image is plotted on a color wheel. Item 9. The image processing apparatus according to Item 8 .   An image processing method for processing image information for an image forming apparatus to execute image formation,
  Obtaining the image information;
  Based on the image information, a plurality of chromatic color information related to the usage amount of a plurality of types of chromatic developer used when the image forming apparatus executes image formation,
  Generating non-use developer information indicating that at least one of the plurality of chromatic color developers is not used based on the image information;
  The image information is converted into a format having brightness, saturation, and hue as parameters, and achromatic color information related to the amount of achromatic developer used when the image forming apparatus executes image formation is converted to the lightness. An image processing method, characterized in that the image processing method is generated on the basis of the parameters.   A control program causing an image processing apparatus to execute the image processing method according to claim 10.   12. A recording medium in which the control program according to claim 11 is recorded in a format readable by an image processing apparatus.

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