Color image forming apparatus and color image forming method

Abstract

To reduce blurring of ink in a boundary of an image (line or character) in the background.SOLUTION: A color image forming device (ink-jet recording device 100) comprises: line region detection means 31 for detecting a line region; background region detection means 32 for detecting a background region adjacent to the line region; line region color detection means 33 for detecting a color of the line region; background region color detection means 34 for detecting a color of the background region; color comparison region 35 for comparing the color of the line region with the color of the background region; and correction means 36 for correcting an ink amount. The correction means corrects the ink amount in accordance with a combination pattern of the ink colors of the line region and the background region determined through the color comparison carried out by the color comparison means.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a color image forming apparatus and a color image forming method.

Background Art

[0002] As a color image forming apparatus, an inkjet recording apparatus that performs printing by an inkjet method has become widespread. In a color image forming apparatus, when printing by overlapping inks of each color, bleeding may occur at the contour of a line (character). To reduce bleeding, there are techniques for thinning the boundary between the background and the line (character), techniques for reducing the dot shape, and techniques for controlling ON / OFF and intensity of correction according to the direction and thickness of the line (character) (see, for example, Patent Documents 1 to 4).

[0003] The technique described in Patent Document 1 adjusts the ink ejection amount per time by referring to the ink diffusion information from the line thickness information, and switches the correction amount according to the line thickness. Further, the technique described in Patent Document 2 thins out the ink amount at the contour of the line or changes the dot size, and switches the correction amount depending on whether it is a horizontal line or a vertical line. Further, the technique described in Patent Document 3 reduces the density of a region slightly inside from the contour of the line. Further, the technique described in Patent Document 4 provides a bleeding interference reduction region between the first image and the second image to reduce ink bleeding interference.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

[0005] However, the inventors' research revealed that in images with a background color (lines and text), the amount of bleeding differs depending on the order in which the ink used for the background and the lines (text) land. For example, drawing the lines (text) first and then the background (including the line drawing) afterward results in less bleeding. Conventional technology suppresses bleeding with the same correction amount (method) regardless of the order of landing (i.e., the combination pattern of ink colors in the line and background areas), making it difficult to optimize bleeding suppression, and there is room to further reduce ink bleeding at the boundaries of images with a background (lines and text).

[0006] Furthermore, the inventors' research revealed that even when the background and lines (text) are different colors, resist misalignment can occur, resulting in either an excessive or not excessive total ink amount at the boundary, thus affecting the amount of bleeding. For example, if the background is yellow (Y) and the lines (text) are a mixture of cyan and magenta (C+M), resist misalignment can cause the boundary color to become a mixture of yellow, cyan, and magenta (Y+C+M). In this case, the amount of bleeding increases significantly. Conventional technology does not consider the combination patterns of ink colors in the line and background regions, making it difficult to optimize the suppression of such bleeding, and there is room for further reduction of ink bleeding at the boundaries of images (lines and text) with backgrounds.

[0007] The present invention has been made in view of the problems of the prior art described above, and the object of the present invention is to provide a color image forming apparatus and a color image forming method that reduce ink bleeding at the boundaries of images (lines and characters) with a background. [Means for solving the problem]

[0008] The above-mentioned problems of the present invention are solved by the following means.

[0009] (1) A color image forming apparatus comprising: line region detection means for detecting line regions; background region detection means for detecting background regions adjacent to the line regions; line region color detection means for detecting the color of the line regions; background region color detection means for detecting the color of the background regions; color comparison means for comparing the color of the line regions with the color of the background regions; and correction means for correcting the amount of ink, wherein the correction means corrects the amount of ink according to the combination pattern of ink colors of the line regions and background regions determined by the color comparison by the color comparison means.

[0010] (2) A color image forming apparatus according to (1) above, wherein a region in the ink used in the line region that contains color ink printed after the ink used in the background region is defined as feature region Ar1, and a region in the ink used in the line region that contains color ink printed before the ink used in the background region is defined as feature region Ar2, and the correction means corrects the amount of ink in the feature region when at least one of feature regions Ar1 or Ar2 is detected by color comparison by the color comparison means.

[0011] (3) The color image forming apparatus according to (2) above, wherein the correction means reduces the density of the feature region, and the amount of reduction in the density of the feature region Ar1 is set to be greater than that of the feature region Ar2.

[0012] (4) A color image forming apparatus according to (1) above, wherein a region in the ink used in the background region that contains color ink printed after the ink used in the line region is defined as feature region Ar1, and a region in the ink used in the background region that contains color ink printed before the ink used in the line region is defined as feature region Ar2, and the correction means corrects the amount of ink in the feature region when it detects at least one of feature regions Ar1 or Ar2 by color comparison by the color comparison means.

[0013] (5) The color image forming apparatus according to (4) above, wherein the correction means reduces the density of the feature region, and the amount of reduction in the density of the feature region Ar2 is set to be greater than that of the feature region Ar1.

[0014] (6) A feature region Ar11 is a region in the ink used in the line region in which there is color ink that is printed after the ink used in the background region, and in which the ink used in the line region does not contain the ink used in the background region; a feature region Ar12 is a region in the ink used in the line region in which there is color ink that is printed after the ink used in the background region, and in which the ink used in the line region contains the ink used in the background region; and a feature region Ar12 is a region in the ink used in the line region in which there is color ink that is printed before the ink used in the background region. A color image forming apparatus according to (1) above, wherein a region is defined as a feature region Ar21 in which the ink used in the line region does not include the ink used in the background region, and a region is defined as a feature region Ar22 in which the ink used in the line region contains color ink that is printed before the ink used in the background region, and the ink used in the line region does include the ink used in the background region, and the correction means corrects the amount of ink in the feature region when at least one of the feature regions Ar11, Ar12, Ar21, and Ar22 is detected by color comparison by the color comparison means.

[0015] (7) The color image forming apparatus according to (6) above, wherein the correction means reduces the density of a feature region, and the reduction amount of the density of feature region Ar11 is set to be greater than that of feature region Ar12, the reduction amount of the density of feature region Ar21 is set to be greater than that of feature region Ar22, and the reduction amount of the density of feature region Ar12 is set to be greater than that of feature region Ar22.

[0016] (8) A region in the background region where there is color ink that is printed after the ink used in the line region, and where there is no ink used in the line region, is defined as feature region Ar11; a region in the background region where there is color ink that is printed after the ink used in the line region, and where there is ink used in the line region, is defined as feature region Ar12; and a region in the background region where there is color ink that is printed before the ink used in the line region. A color image forming apparatus according to (1) above, wherein a region is defined as a feature region Ar21 in which the ink used in the background region does not include the ink used in the line region, and a region is defined as a feature region Ar22 in which the ink used in the background region contains color ink that is printed before the ink used in the line region, and the ink used in the background region does include the ink used in the line region, and the correction means corrects the amount of ink in the feature region when at least one of the feature regions Ar11, Ar12, Ar21, and Ar22 is detected by color comparison by the color comparison means.

[0017] (9) The color image forming apparatus according to (8) above, wherein the correction means reduces the density of feature regions, and the amount of density reduction for feature region Ar12 is set to be greater than that for feature region Ar11, the amount of density reduction for feature region Ar22 is set to be greater than that for feature region Ar21, and the amount of density reduction for feature region Ar21 is set to be greater than that for feature region Ar11.

[0018] (10) The color image forming apparatus according to (1) above, wherein the line region is composed of multiple colors of ink, and the background region is composed of one or more colors of ink.

[0019] (11) The color image forming apparatus according to (1) above, wherein the line region is composed of one color of ink, and the background region is composed of multiple or more colors of ink.

[0020] (12) The color image forming apparatus according to (1) above, wherein the total value of the ink amount in the line area is a predetermined value or more, and the background area is composed of one or more colors of ink.

[0021] (13) The color image forming apparatus according to (1) above, wherein the line area is composed of one or more colors of ink, and the total value of the ink amount in the background area is a predetermined value or more.

[0022] (14) The color image forming apparatus according to (1) above, wherein the correction means corrects the ink amount according to the type of the recording medium.

[0023] (15) The color image forming apparatus according to (1) above, wherein the corrected ink amount is obtained by multiplying the ink amount of the print command by a correction coefficient, and the correction coefficient for correcting the ink amount is less than 1.0.

[0024] [[ID=l5]] (16) A color image forming method, comprising: a line area detection step of detecting a line area; a background area detection step of detecting a background area adjacent to the line area; a line area color detection step of detecting the color of the line area; a background area color detection step of detecting the color of the background area; a color comparison step of comparing the color of the line area with the color of the background area; and a correction step of correcting the ink amount. In the correction step, the ink amount is corrected according to the combination pattern of the ink colors of the line area and the background area determined by the color comparison in the color comparison step.

Advantages of the Invention

[0025] According to the present invention, it is possible to reduce bleeding of ink at the boundary of an image (lines or characters) with a background.

Brief Description of the Drawings

[0026] [Figure 1] It is a configuration diagram of an inkjet recording apparatus as a color image forming apparatus according to an embodiment. [Figure 2] It is a configuration diagram of a control unit. [Figure 3] It is an explanatory diagram of patterns of a line area and a background area. [Figure 4A] This is an explanatory diagram (1) of the line region and background region. [Figure 4B] This is diagram (2) illustrating the line region and background region. [Figure 4C] This is diagram (3) illustrating the line region and background region. [Figure 4D] This is diagram (4) illustrating the line region and background region. [Figure 4E] This is an explanatory diagram (5) of the line region and background region. [Figure 4F] This is an explanatory diagram (6) of the line region and background region. [Figure 4G] This is an explanatory diagram (7) of the line region and background region. [Figure 5A] This is an explanatory diagram before correction. [Figure 5B] This is the corrected explanatory diagram. [Figure 6A] This is an explanatory diagram before correction. [Figure 6B] This is the corrected explanatory diagram. [Figure 7A] This is an explanatory diagram before correction. [Figure 7B] This is the corrected explanatory diagram. [Figure 8] This is an explanatory diagram of ink bleeding. [Figure 9] This is a graph showing the results of the bleeding amount measurement. [Modes for carrying out the invention]

[0027] The present invention provides image processing that suppresses bleeding, and is particularly applicable to inkjet recording devices using water-based inks. The present invention reduces ink bleeding at the boundary by correcting the amount of ink at the boundary between the line region and the background region according to the combination pattern of ink colors of the line region and the background region.

[0028] Embodiments of the present invention will be described in detail below with reference to the drawings. Note that the drawings are merely schematic representations to allow for a thorough understanding of the present invention. Therefore, the present invention is not limited to the illustrated examples. Furthermore, in each drawing, common or similar components are denoted by the same reference numerals, and their redundant descriptions are omitted.

[0029] <Configuration of a color image forming apparatus> The configuration of the color image forming apparatus according to this embodiment will be described below with reference to Figures 1 and 2. In this embodiment, the description assumes that the color image forming apparatus is configured as an inkjet recording apparatus using water-based ink. Figure 1 is a configuration diagram of the inkjet recording apparatus 100 as the color image forming apparatus according to this embodiment.

[0030] As shown in Figure 1, the inkjet recording device 100 includes an operation display unit 11, an image forming means 12, a communication I / F means 13, a control unit 21, and a storage unit 22. The operation display unit 11 is a means for inputting and displaying various types of information. The operation display unit 11 consists of a touch panel display or the like, which has an input function added to the display unit. The image forming means 12 is a means for forming a printed image on a recording medium. In this embodiment, the image forming means 12 is described as being configured to print a color image using four inks: cyan (C), magenta (M), yellow (Y), and black (K). The communication interface 13 is a means for communicating with external devices such as a server. The inkjet recording device 100 prints based on a print command 61 (see Figure 2) obtained from an external source via the server or the like. The control unit 21 is a means for controlling the operation of each part of the inkjet recording device 100. The memory unit 22 is composed of semiconductor memory or the like, and is a means for storing various kinds of information.

[0031] The memory unit 22 stores the control program 51, the correction coefficient 52, and the correction control table 53. The control program 51 causes the CPU (Central Processing Unit) mounted on the inkjet recording device 100 to function as the control unit 21. The correction factor of 52 is a coefficient multiplied by the amount of ink specified in the print command. The correction control table 53 is a lookup table for correction control of the ink amount in the print command.

[0032] <Configuration of the control unit> As shown in Figure 2, the control program 51 causes the CPU (Central Processing Unit) mounted on the inkjet recording device 100 to function as a control unit 21 having a line region detection means 31, a background region detection means 32, a line region color detection means 33, a background region color detection means 34, a color comparison means 35, and a correction means 36.

[0033] Furthermore, as shown in Figure 2, the inkjet recording device 100 obtains a print command 61 from an external source via a server or the like through a communication I / F means 13 (see Figure 1). The print command 61 contains image information for each color: cyan (C), magenta (M), yellow (Y), and black (K) (hereinafter sometimes referred to as "CMYK data").

[0034] The line region detection means 31 is a means for detecting line regions (character regions) from the image information of each color included in the print command 61. The line region detection means 31 uses a differential filter to extract regions where density changes occur and identifies the denser parts as line regions (character regions). This identifies one or two dots inside the outline of the line (character). The width of the line (character) changes depending on the size of the differential filter, etc. The input to the differential filter can be, for example, the sum of the CMYK data.

[0035] The background area detection means 32 is a means for detecting background areas adjacent to line areas from the image information of each color included in the print command 61. The background area detection means 32 uses a differential filter to extract areas where density changes occur and identifies areas with lower density as background areas. This identifies one or two dots inside the background contour. The width of the background contour varies depending on the size of the differential filter, etc. The input to the differential filter can be, for example, the sum of the CMYK data.

[0036] The line region color detection means 33 is a means for detecting the color of the line region detected by the line region detection means 31. The line region color detection means 33 determines the ink color (LINE_C, M, Y, K) used in the line region (character region) and the detected pixels. The line region color detection means 33 determines that ink colors (Cin, Min, Yin, Kin) that exceed a predetermined threshold (LINEth) are present (value "1"), and ink colors (Cin, Min, Yin, Kin) that are below the predetermined threshold (LINEth) are absent (value "0"). LINE_C = (Cin>LINEth)? 1:0 …(1) LINE_M = (Min>LINEth)? 1:0 …(2) LINE_Y = (Yin>LINEth)? 1:0 …(3) LINE_K = (Kin>LINEth)? 1:0 …(4)

[0037] Here, the part of equation (1) above, "LINE_C = (Cin>LINEth)?", is a determination formula to determine whether the cyan ink portion (Cin) exceeds the threshold of the cyan line region (LINEth) (the same applies to equations (2), (3), and (4) for other colors). The part to the right of it, "1:0", indicates that if the determination formula is true (i.e., the cyan ink portion (Cin) exceeds the threshold of the cyan line region (LINEth)), the value will be "1", and if the determination formula is false (i.e., the cyan ink portion (Cin) is less than or equal to the threshold of the cyan line region (LINEth)), the value will be "0", and the value will be output accordingly (the same applies to equations (2), (3), and (4) for other colors).

[0038] The background area color detection means 34 is a means for detecting the color of the background area detected by the background area detection means 32. The background area color detection means 34 determines the ink color (BACK_C, M, Y, K) used in the background area and the detected pixels. The background area color detection means 34 determines that ink colors (Cin, Min, Yin, Kin) that exceed a predetermined threshold (BACKth) are present (value "1"), and ink colors (Cin, Min, Yin, Kin) that are below the predetermined threshold (BACKth) are absent (value "0"). BACK_C = (Cin>BACKth)? 1:0 …(5) BACK_M = (Min>BACKth)? 1:0 …(6) BACK_Y = (Yin>BACKth)? 1:0 …(7) BACK_K = (Kin>BACKth)? 1:0 …(8)

[0039] Here, the part of equation (5) above, "BACK_C = (Cin>BACKth)?", is a determination formula to determine whether the cyan ink portion (Cin) exceeds the threshold of the cyan background area (BACKth) (the same applies to equations (6), (7), and (8) for other colors). The part to the right of it, "1:0", indicates that if the determination formula is true (i.e., the cyan ink portion (Cin) exceeds the threshold of the cyan background area (BACKth)), the value will be "1", and if the determination formula is false (i.e., the cyan ink portion (Cin) is less than or equal to the threshold of the cyan background area (BACKth)), the value will be "0", and the value will be output accordingly (the same applies to equations (6), (7), and (8) for other colors).

[0040] The color comparison means 35 is a means for comparing the color of the line region with the color of the background region. The color comparison means 35 refers to the correction control table 53 (see Figure 1) to compare the color of the line region (LINE_C,M,Y,K) with the color of the background region (BACK_C,M,Y,K), and refers to the correction coefficient 52 (see Figure 1) to output correction coefficients (Cx,Mx,Yx,Kx) corresponding to the pattern of the line region and background region determined by the color comparison (color comparison) to the correction means 36. In this embodiment, the color comparison means 35 will be described as detecting feature regions Ar1,Ar2,Ar11,Ar12,Ar21,Ar22 (see Figure 3) as the pattern of the line region and background region determined by the color comparison, and outputting correction coefficients (Cx,Mx,Yx,Kx) corresponding to each feature region to the correction means 36. Feature regions Ar1, Ar2, Ar11, Ar12, Ar21, and Ar22 will be described later in the chapter <Overview of Line and Background Region Patterns>. The correction coefficient 52 (see Figure 1) represents the correction coefficient (Cx, Mx, Yx, Kx) for each color ink. The correction coefficient (Cx, Mx, Yx, Kx) represents the multiplier applied to the image information (CMYK data) of each color included in the print command 61, and has a value of 0.0 to 1.0 (×0.0 to ×1.0).

[0041] The correction means 36 is a means for correcting the amount of ink according to the patterns of the line region and background region determined by the color comparison means 35. In this embodiment, the color comparison means 35 outputs correction coefficients (Cx, Mx, Yx, Kx) to the correction means 36 according to the patterns of the line region and background region (for example, the feature regions Ar1, Ar2, Ar11, Ar12, Ar21, Ar22 shown in Figure 3), and the correction means 36 corrects the amount of ink by multiplying the image information (CMYK data) of each color by the correction coefficients (Cx, Mx, Yx, Kx). However, the correction means 36 may also obtain pattern information of the line region and background region (for example, information representing the position and configuration of the feature regions Ar1, Ar2, Ar11, Ar12, Ar21, Ar22 shown in Figure 3) from the color comparison means 35, obtain correction coefficients (Cx, Mx, Yx, Kx) corresponding to the patterns of the line region and background region obtained by color comparison by referring to the correction coefficient 52 (see Figure 1), and correct the amount of ink by multiplying the image information (CMYK data) of each color by the correction coefficients (Cx, Mx, Yx, Kx).

[0042] When the correction means 36 corrects the amount of ink, it generates bitmap data 62 for image printing based on the image information of each color included in the print command 61. The bitmap data 62 is pixel-by-pixel data for each color: cyan, magenta, yellow, and black. The inkjet recording device 100 then forms a print image on the recording medium using the image forming means 12 based on the bitmap data 62.

[0043] <Overview of line and background area patterns> The following describes the patterns of line and background regions with reference to Figure 3. Figure 3 is an explanatory diagram of the line and background region patterns. Figure 3 shows that the correction coefficient is changed according to the combination pattern of ink colors for the line and background regions. In Figure 3, seven examples of line and background region patterns, from the first to the seventh pattern, are arranged horizontally, and items such as the definition of the line and background regions, feature regions, and correction coefficients are arranged vertically, showing examples of combinations of each item in each pattern. In Figure 3, "○" indicates that the condition is met, and "×" indicates that the condition is not met.

[0044] In Figure 3, the following items are arranged vertically. The first row shows the image (composition) of each pattern from Pattern 1 to Pattern 7. Details of each pattern's image will be described later, referring to Figures 4A to 4G. The second line shows the conditions for the line area: "The line area has two or more colors OR the total amount of ink is above a specified value." The third line indicates the background area condition: "The background area must have one or more colors." The fourth line indicates the condition for the order in which the ink is applied: "lines are printed later" (the line area is printed after the background area). The fifth line indicates the condition for the order in which the ink will land: "lines are printed first" (the line area is printed before the background area). The sixth line indicates the condition that "different inks are used for lines and backgrounds" (different inks are used for the line area and the background area). The seventh line shows an example of the "detection result" and "correction coefficient" in "Example 1," which will be described later. The eighth line shows an example of the "detection result" and "correction coefficient" in "Example 2," which will be described later.

[0045] Figures 4A to 4G are explanatory diagrams of the line region and background region, respectively. Figures 4A to 4G show the image (configuration) of each pattern from the first to the seventh pattern shown in Figure 3, respectively. Figures 4A to 4G show an example in which the inkjet recording device 100 records (coats) the first color ink 81 (see Figures 4A to 4G), the second color ink 82 (see Figures 4B to 4G), and the third color ink 83 (see Figures 4F and 4G) onto the recording medium 80. The ink of each color lands first on the side closer to (below) the recording medium 80. Here, we will explain assuming that the first color ink 81 is cyan (C), the second color ink 82 is magenta (M), and the third color ink 83 is yellow (Y).

[0046] As shown in Figure 4A, the first pattern has a configuration in which a line region Ln formed by the first color ink 81 is placed on the recording medium 80.

[0047] As shown in Figure 4B, the second pattern has a configuration in which a line region Ln formed by the first color ink 81 and the second color ink 82 is placed on the recording medium 80.

[0048] As shown in Figure 4C, the third pattern has a background region Bk having a partially missing portion formed by the first color ink 81 placed on the recording medium 80, and a line region Ln formed by the second color ink 82 placed on the partially missing portion of the first color ink 81.

[0049] As shown in Figure 4D, the fourth pattern has a configuration in which a background area Bk formed by a first-color ink 81 is placed on the recording medium 80, and a line area Ln formed by a second-color ink 82 is placed on top of the first-color ink 81.

[0050] As shown in Figure 4E, the fifth pattern has a configuration in which a line region Ln formed by the first color ink 81 is placed on the recording medium 80, and a background region Bk formed by the second color ink 82 is placed on top of the first color ink 81.

[0051] As shown in Figure 4F, the sixth pattern has a background region Bk having a partially missing portion formed by the first color ink 81, which is placed on the recording medium 80, and a line region Ln formed by the second color ink 82 and the third color ink 83 is placed on the partially missing portion of the first color ink 81.

[0052] As shown in Figure 4G, the seventh pattern has a configuration in which a line region Ln formed by a first color ink 81 and a second color ink 82 is placed on the recording medium 80, and a background region Bk having a partially missing portion formed by a third color ink 83 is placed on the second color ink 82.

[0053] Returning to Figure 3, the items in the second to sixth rows of the first pattern (see Figure 4A) are, respectively, "× (Does not meet the condition)", "× (Does not meet the condition)", "× (Does not meet the condition)", "〇 (Meets the condition)", and "〇 (Meets the condition)".

[0054] Furthermore, in the second pattern (see Figure 4B), the items in rows 2 through 6 are "○ (Condition met)", "× (Condition not met)", "× (Condition not met)", "○ (Condition met)", and "○ (Condition met)".

[0055] Furthermore, in the third pattern (see Figure 4C), the items in the second to sixth rows are "× (does not meet the condition)", "〇 (meets the condition)", "〇 (meets the condition)", "× (does not meet the condition)", and "〇 (meets the condition)".

[0056] Furthermore, in the fourth pattern (see Figure 4D), the items in the second to sixth rows are "○ (Condition met)", "○ (Condition met)", "○ (Condition met)", "× (Condition not met)", and "× (Condition not met)".

[0057] Furthermore, in the fifth pattern (see Figure 4E), the items in the second to sixth rows are "○ (Condition met)", "○ (Condition met)", "× (Condition not met)", "○ (Condition met)", and "× (Condition not met)".

[0058] Furthermore, in the sixth pattern (see Figure 4F), the items in the second to sixth rows are "○ (Condition met)", "○ (Condition met)", "○ (Condition met)", "× (Condition not met)", and "○ (Condition met)".

[0059] Furthermore, in the 7th pattern (see Figure 4G), the items in the 2nd to 6th rows are "○ (Condition met)", "○ (Condition met)", "× (Condition not met)", "○ (Condition met)", and "○ (Condition met)".

[0060] <Example 1> In Example 1, the color comparison means 35 detects feature regions Ar1 and Ar2 that meet the following conditions by comparing the color of the line region with the color of the background region (color comparison), and the correction means 36 corrects the amount of ink at the boundary between the line region and the background region of the feature regions Ar1 and Ar2. Although the examples of patterns shown in Figures 3 and 4A to 4G only show three inks: the first color ink 81 of cyan (C), the second color ink 82 of magenta (M), and the third color ink 83 of yellow (Y), here we will explain assuming that the inkjet recording device 100 records cyan (C), magenta (M), yellow (Y), and black (K) inks in order onto the recording medium (paper).

[0061] In this embodiment 1, the explanation assumes that when the correction means 36 corrects the amount of ink, the reduction in density of feature area Ar1 is set to be greater than that of feature area Ar2. However, as explained in the <Supplementary Information> section below, if the definitions of the line area (character area) and background area in the feature area are reversed, it is preferable to set the reduction in density of feature area Ar2 to be greater than that of feature area Ar1.

[0062] Here, "feature region Ar1" refers to the area within the ink used in the line region that contains color ink that is printed after the ink used in the background region. In other words, "feature region Ar1" refers to the area within the ink used in the line region that contains ink that will overwrite the background and line regions, which have already been drawn with other inks.

[0063] Furthermore, "feature region Ar2" refers to the area within the ink used in the line region where color ink is printed before the ink used in the background region. In other words, "feature region Ar2" refers to the area within the ink used in the line region where ink is drawn directly onto the paper before both the background and line regions have been drawn.

[0064] In feature region Ar1, the ink used in the line region (text region) includes color inks that are printed later than the ink used in the background region.

[0065] Furthermore, in the feature region Ar2, among the inks used in the line region (text region), there are color inks that are printed before the inks used in the background region.

[0066] Feature regions Ar1 and Ar2 have a value of "1" for two or more of LINE_C, M, Y, K in equations (1) to (4) above. Also, feature regions Ar1 and Ar2 have a value of "1" for one or more of BACK_C, M, Y, K in equations (5) to (8) above. The color comparison means 35 identifies feature regions Ar1 and Ar2 using the logic of LINE_C, M, Y, K and BACK_C, M, Y, K.

[0067] A good logic for identifying feature region Ar1 is that the color that hits later than the color of BACK_*=1 is LINE_*=1. Similarly, a good logic for identifying feature region Ar2 is that the color that hits earlier than the color of BACK_*=1 is LINE_*=1. Here, "*" represents one of the colors C (cyan), M (magenta), Y (yellow), or K (black) (and so on).

[0068] If the pattern does not fall under either feature region Ar1 or Ar2, the combination of ink colors in the line region and background region will be considered a pattern outside of feature regions Ar1 and Ar2.

[0069] In the first example shown in Figure 3, when the image forming pattern is one of the first to third patterns, the color comparison means 35 detects areas of the pattern other than the feature areas Ar1 and Ar2. In this case, the correction coefficient is set to 1.0 (×1.0). The correction means 36 multiplies the amount of ink by 1.0 (×1.0) of the correction coefficient at the boundary between the line area and the background area of ​​that region. In this process, for the first pattern, there is no background area and the line area is one color, so it is determined to be an area of ​​the pattern other than the feature areas Ar1 and Ar2, and no correction is performed on any of the ink colors. Similarly, for the second pattern, there is no background area, so it is determined to be an area of ​​the pattern other than the feature areas Ar1 and Ar2, and no correction is performed on any of the ink colors. Similarly, for the third pattern, there is a background area, but the line area is one color, so it is determined to be an area of ​​the pattern other than the feature areas Ar1 and Ar2, and no correction is performed on any of the ink colors.

[0070] Furthermore, when the image formation pattern is the fourth or sixth pattern, the color comparison means 35 detects the feature region Ar1. In this case, the correction coefficient is 0.7 times (×0.7). The correction means 36 multiplies the ink amount by 0.7 times (×0.7) the correction coefficient at the boundary between the line region and the background region of the feature region Ar1. For example, the correction means 36 multiplies the ink amount of the pixels in the input image that are determined to be the feature region Ar1 and are determined to be LINE_C,M,Y,K=1 or BACK_C,M,Y,K=1 by 0.7 times (×0.7) the correction coefficient. In this process, for the fourth or sixth pattern, there is a background region, the line region is two colors, and there is ink that is printed after the background, so it is determined to be the feature region Ar1, and correction is performed on the ink at the boundary between the line region and the background region of the feature region Ar1.

[0071] Furthermore, when the image formation pattern is the fifth or seventh pattern, the color comparison means 35 detects the feature region Ar2. In this case, the correction coefficient becomes 0.8 times (×0.8). The correction means 36 multiplies the ink amount by 0.8 times (×0.8) the correction coefficient at the boundary between the line region and the background region of the feature region Ar2. For example, the correction means 36 multiplies the ink amount of the pixels in the input image that are determined to be the feature region Ar2 and are determined to be LINE_C,M,Y,K=1 or BACK_C,M,Y,K=1 by 0.8 times (×0.8) the correction coefficient. In this process, for the fifth or seventh pattern, there is a background region, the line region is two colors, and there is ink that is printed before the background, so it is determined to be the feature region Ar2, and correction is performed on the ink at the boundary between the line region and the background region of the feature region Ar2.

[0072] <Example 2> Example 2 limits the conditions under which bleeding occurs more specifically (in more detail) than in Example 1. In Example 2, the color comparison means 35 detects feature regions Ar11, Ar12, Ar21, and Ar22 that meet the following conditions by comparing the color of the line region with the color of the background region (color comparison), and the correction means 36 corrects the amount of ink at the boundary between the line region and the background region of the feature regions Ar11, Ar12, Ar21, and Ar22. Here, it is explained that the inkjet recording device 100 records cyan (C), magenta (M), yellow (Y), and black (K) inks in order onto the recording medium (paper).

[0073] In this embodiment 2, the explanation assumes that when the correction means 36 corrects the amount of ink, it sets the reduction amount of density in feature area Ar11 to be greater than that of feature area Ar12, the reduction amount of density in feature area Ar21 to be greater than that of feature area Ar22, and the reduction amount of density in feature area Ar12 to be greater than that of feature area Ar22. However, as explained in the <Supplementary> section below, if the definitions of the line area (character area) and background area in the feature area are reversed, it is preferable to set the reduction amount of density in feature area Ar12 to be greater than that of feature area Ar11, the reduction amount of density in feature area Ar22 to be greater than that of feature area Ar21, and the reduction amount of density in feature area Ar21 to be greater than that of feature area Ar11.

[0074] Here, "feature region Ar11" refers to a region within the ink used in the line region where color ink is printed after the ink used in the background region, and where the ink used in the line region does not include the ink used in the background region. In other words, "feature region Ar11" refers to a region within the ink used in the line region where ink is used to overwrite an area where both the background region and the line region have already been drawn with other inks, and where the ink used in the line region does not include the ink used in the background region.

[0075] Furthermore, "feature region Ar12" refers to a region within the ink used in the line region where color ink is printed after the ink used in the background region, and where the ink used in the line region also contains the ink used in the background region. In other words, "feature region Ar12" refers to a region within the ink used in the line region where ink is used to overwrite an area where both the background region and the line region have already been drawn with other inks, and where the ink used in the line region also contains the ink used in the background region.

[0076] Furthermore, "feature region Ar21" refers to a region within the ink used in the line region where color ink is printed before the ink used in the background region, and where the ink used in the line region does not include the ink used in the background region. In other words, "feature region Ar21" refers to a region within the ink used in the line region where ink is drawn directly onto the paper before both the background region and the line region are drawn, and where the ink used in the line region does not include the ink used in the background region.

[0077] Furthermore, "feature region Ar22" refers to a region within the ink used in the line region where color ink is printed before the ink used in the background region, and where the ink used in the line region also contains the ink used in the background region. In other words, "feature region Ar22" refers to a region within the ink used in the line region (text region) where ink is drawn directly onto the paper before both the background region and the line region are drawn, and where the ink used in the line region also contains the ink used in the background region.

[0078] In feature region Ar11, some of the inks used in the line region (text region) are colored inks that are printed later than the inks used in the background region. Furthermore, the inks used in the background region and the line region (text region) are different from those used in the background region.

[0079] In feature region Ar12, some color inks used in the line region (text region) are printed later than those used in the background region. Additionally, the same inks exist in both the background and line regions (text regions).

[0080] In feature region Ar21, some color inks used in the line region (text region) are printed before the inks used in the background region. Furthermore, the inks used in the background region and the line region (text region) are different from those used in the background region.

[0081] In the feature region Ar22, some color inks used in the line region (text region) are printed before the inks used in the background region. Additionally, the same inks exist in both the background region and the line region (text region).

[0082] Feature regions Ar11, Ar12, Ar21, and Ar22 have a value of "1" for two or more of LINE_C, M, Y, and K in equations (1) to (4) above. Also, feature regions Ar11, Ar12, Ar21, and Ar22 have a value of "1" for one or more of BACK_C, M, Y, and K in equations (5) to (8) above. The color comparison means 35 identifies feature regions Ar11, Ar12, Ar21, and Ar22 using the logic of LINE_C, M, Y, K and BACK_C, M, Y, K.

[0083] A good logic for identifying feature region Ar11 would be that LINE_*=1 is a color that hits later than the color of BACK_*=1, and that the colors of BACK_*=1 and LINE_*=1 are different. Similarly, a good logic for identifying feature region Ar12 would be that LINE_*=1 is a color that hits later than the color of BACK_*=1, and that BACK_*=1 and LINE_*=1 have the same color ink. Similarly, a good logic for identifying feature region Ar21 would be that LINE_*=1 is a color that hits earlier than the color of BACK_*=1, and that the colors of BACK_*=1 and LINE_*=1 are different. Similarly, a good logic for identifying feature region Ar22 would be that LINE_*=1 is a color that hits earlier than the color of BACK_*=1, and that BACK_*=1 and LINE_*=1 have the same color ink.

[0084] If the pattern does not fall under any of the feature regions Ar11, Ar12, Ar21, or Ar22, the combination of ink colors in the line region and background region will fall under a region other than the feature regions Ar11, Ar12, Ar21, or Ar22.

[0085] In the second example shown in Figure 3, when the image formation pattern is one of the first to third patterns, the color comparison means 35 detects areas of the pattern other than the feature regions Ar11, Ar12, Ar21, and Ar22. In this case, the correction coefficient is set to 1.0 (×1.0). The correction means 36 multiplies the amount of ink by 1.0 (×1.0) of the correction coefficient at the boundary between the line region and the background region of that area. In this process, for the first pattern, there is no background region and the line region is one color, so it is determined to be an area of ​​the pattern other than the feature regions Ar11, Ar12, Ar21, and Ar22, and no correction is performed on any of the ink colors. Similarly, for the second pattern, there is no background region, so it is determined to be an area of ​​the pattern other than the feature regions Ar11, Ar12, Ar21, and Ar22, and no correction is performed on any of the ink colors. Furthermore, in the third pattern, although there is a background area, the line area is a single color, so it is determined to be a pattern area other than the feature areas Ar11, Ar12, Ar21, and Ar22, and no correction is applied to any of the ink colors.

[0086] Furthermore, when the image formation pattern is the fourth pattern, the color comparison means 35 detects the feature region Ar12. In this case, the correction coefficient becomes 0.7 times (×0.7). The correction means 36 multiplies the ink amount by 0.7 times (×0.7) the correction coefficient at the boundary between the line region and the background region of the feature region Ar12. For example, the correction means 36 multiplies the ink amount of pixels in the input image that are determined to be the feature region Ar12 and are determined to be LINE_C,M,Y,K=1 or BACK_C,M,Y,K=1 by 0.7 times (×0.7) the correction coefficient. In this process, in the fourth pattern, there is a background region, the line region is two colors, and there is ink that is printed after the background, so it is determined to be the feature region Ar12, and correction is performed on the ink at the boundary between the line region and the background region of the feature region Ar12.

[0087] Furthermore, when the image formation pattern is the fifth pattern, the color comparison means 35 detects the feature region Ar22. In this case, the correction coefficient becomes 0.8 times (×0.8). The correction means 36 multiplies the ink amount by 0.8 times (×0.8) the correction coefficient at the boundary between the line region and the background region of the feature region Ar22. For example, the correction means 36 multiplies the ink amount of pixels in the input image that are determined to be the feature region Ar22 and are determined to be LINE_C,M,Y,K=1 or BACK_C,M,Y,K=1 by 0.8 times (×0.8) the correction coefficient. In this process, in the fifth pattern, there is a background region, the line region is two colors, and there is ink that is printed before the background, so it is determined to be the feature region Ar22, and correction is performed on the ink at the boundary between the line region and the background region of the feature region Ar22.

[0088] Furthermore, when the image formation pattern is the sixth pattern, the color comparison means 35 detects the feature region Ar11. In this case, the correction coefficient becomes 0.5 times (×0.5). The correction means 36 multiplies the ink amount by 0.5 times (×0.5) the correction coefficient at the boundary between the line region and the background region of the feature region Ar11. For example, the correction means 36 multiplies the ink amount of pixels in the input image that are determined to be the feature region Ar11 and are determined to be LINE_C,M,Y,K=1 or BACK_C,M,Y,K=1 by 0.5 times (×0.5) the correction coefficient. In this process, in the sixth pattern, there is a background region, the line region is two colors, and there is ink that is printed after the background, so it is determined to be the feature region Ar11, and correction is performed on the ink at the boundary between the line region and the background region of the feature region Ar11.

[0089] Furthermore, when the image formation pattern is the seventh pattern, the color comparison means 35 detects the feature region Ar21. In this case, the correction coefficient becomes 0.6 times (×0.6). The correction means 36 multiplies the ink amount by 0.6 times (×0.6) the correction coefficient at the boundary between the line region and the background region of the feature region Ar21. For example, the correction means 36 multiplies the ink amount of pixels in the input image that are determined to be the feature region Ar21 and are determined to be LINE_C,M,Y,K=1 or BACK_C,M,Y,K=1 by 0.6 times (×0.6) the correction coefficient. In this process, in the seventh pattern, there is a background region, the line region is two colors, and there is ink that is printed before the background, so it is determined to be the feature region Ar21, and correction is performed on the ink at the boundary between the line region and the background region of the feature region Ar21.

[0090] <An example of before and after correction> The following describes an example of the image before and after correction, referring to Figures 5A to 7B. Figures 5A, 6A, and 7A are explanatory diagrams of the image before correction, respectively. Figures 5B, 6B, and 7B are explanatory diagrams of the image after correction, respectively. Figures 5A to 7B show images of the cross-sectional configuration of the recording medium and the ink applied to the recording medium before and after the correction process.

[0091] Figure 5A shows an example of an image formed by the image information before correction. In the example shown in Figure 5A, a first-color ink 81 that forms the background area is placed on the recording medium 80, and a second-color ink 82 that forms the line area is placed on top of the first-color ink 81. Here, we will explain assuming that the first-color ink 81 is cyan (C) ink and the second-color ink 82 is magenta (M). In this example, the color of the background area is the cyan color of the first-color ink 81, and the color of the line area (text area) is blue (cyan color of the first-color ink 81 + magenta color of the second-color ink 82).

[0092] On the other hand, Figure 5B shows an example of an image formed by corrected image information compared to the example shown in Figure 5A. In the example shown in Figure 5B, in the line region (character region), the density of the magenta second color ink 82 inside the contour (approximately 1 or 2 pixels) is reduced, and the density of the cyan first color ink 81 is reduced both inside (approximately 1 or 2 pixels) and outside (approximately 1 or 2 pixels) the contour. Therefore, in the example shown in Figure 5B, the amount of ink used by the first color ink 81 forming the background region and the second color ink 82 forming the line region is reduced at the boundary between the background region and the line region. Note that the area to be corrected is not limited to this example. For example, it is possible to broaden the range of the area to be corrected, or to limit the area to be corrected to only the inside of the contour of the line region (character region) (the same applies to the other examples shown in Figures 6A to 7B). Also, the correction method is not limited to this example. For example, it is possible to reduce the size of the ink ejected (per dot) (the same applies to the other examples shown in Figures 6A to 7B).

[0093] Figures 6A and 6B show examples where different inks are used for the background area and the line area (text area). In such cases, bleeding is likely to expand, as shown in Figure 8 below. Figure 6A shows an example of an image formed by the image information before correction. In the example shown in Figure 6A, a first-color ink 81 that forms a background area with partial defects is placed on the recording medium 80, and a second-color ink 82 and a third-color ink 83 that form the line area are placed on top of the partial defects of the first-color ink 81. Here, we will explain assuming that the first-color ink 81 is cyan (C), the second-color ink 82 is magenta (M), and the third-color ink 83 is yellow (Y). In this example, the color of the background area is the cyan color of the first-color ink 81, and the color of the line area (text area) is red (magenta color of the second-color ink 82 + yellow color of the third-color ink 83).

[0094] On the other hand, Figure 6B shows an example of an image formed by corrected image information compared to the example shown in Figure 6A. In the example shown in Figure 6B, in the line region (character region), the density of the yellow third color ink 83 inside the contour (about 1 or 2 pixels) is reduced, the density of the magenta second color ink 82 inside the contour (about 1 or 2 pixels) is reduced, and the density of the cyan first color ink 81 inside the contour (about 1 or 2 pixels) is reduced. Therefore, in the example shown in Figure 6B, the amount of ink in the first color ink 81 that forms the background region and the second color ink 82 and third color ink 83 that form the line region is reduced at the boundary between the background region and the line region.

[0095] Figure 7A shows an example of an image formed by the image information before correction. In the example shown in Figure 7A, ink resist misalignment has occurred compared to the example shown in Figure 6A. In the example shown in Figure 6A, there is no ink resist misalignment. In the example shown in Figure 6A, compared to the example shown in Figure 5A, the total ink value of the background area and the total ink value of the line area are the same at the boundary between the background area and the line area, so the amount of ink bleeding in the background area and the line area are almost the same. In contrast, in the example shown in Figure 7A, the magenta second color ink 82 and the yellow third color ink 83 of the line area are shifted to the right of the cyan first color ink 81 of the background area. In the example shown in Figure 7A, the three colors of ink locally overlap on the right side of the boundary of the line area. Therefore, in the example shown in Figure 7A, the local total amount of ink is excessive on the right side of the boundary of the line area compared to the example shown in Figure 6A. Consequently, in the example shown in Figure 7A, the ink bleeding is greater on the right side of the boundary of the line area.

[0096] On the other hand, Figure 7B shows an example of an image formed by corrected image information compared to the example shown in Figure 7A. In the example shown in Figure 7B, ink resist misalignment has occurred, as in the example shown in Figure 6B. In the example shown in Figure 7B, although the three inks locally overlap to the right of the boundary of the line region, the density of the third color ink 83 (yellow) inside the contour (about 1 or 2 pixels) has been reduced in the line region (character region), the density of the second color ink 82 (magenta) inside the contour (about 1 or 2 pixels) has been reduced in the first color ink 81 (cyan). Therefore, in the example shown in Figure 7B, the local total amount of ink to the right of the boundary of the line region is not excessive compared to the example shown in Figure 7A.

[0097] As shown in Figures 5B, 6B, and 7B, the images formed by the corrected image information all have reduced ink volume at the boundary between the background area and the line area. Therefore, the inkjet recording device 100 can lighten the color at the boundary between the background area and the line area. As a result, ink bleeding at the boundary of images with a background (lines and characters) can be reduced.

[0098] <Supplement> This embodiment aims to provide an inkjet recording apparatus 100 (color image forming apparatus) that reduces bleeding 91, for example, as shown in Figure 8. Figure 8 is an explanatory diagram of bleeding. Figure 8 shows that ink bleeding 91 is more likely to occur in lines with a background than in lines without a background (lines formed on a white background). Ink bleeding 91 has the characteristics shown in Figure 9. Figure 9 is a graph of the bleeding amount measurement results. Figure 9 shows that even in lines with a background, the amount of ink bleeding 91 differs depending on the relationship between the background and line colors. In Figure 9, the character C shown by the dashed line is the case of feature region Ar2, where cyan (C) lands before magenta (M), the line (character) is a mixed color of cyan and magenta (C+M), and the background is magenta (M). Furthermore, in Figure 9, the character M shown by the solid line represents the case of feature region Ar1, where cyan (C) lands before magenta (M). In this case, the line (character) is a mixed color of cyan and magenta (C+M), and the background is cyan (C). The inkjet recording device 100 according to this embodiment can reduce such ink bleeding 91 by correcting the amount of ink at the boundary between the line region and the background region according to the combination pattern of ink colors between the line region and the background region.

[0099] In the above-described embodiment 1, the feature region Ar1 is defined as the region within the ink used in the line region (text region) that contains color ink that is printed after the ink used in the background region. Furthermore, the feature region Ar2 is defined as the region within the ink used in the line region (text region) that contains color ink that is printed before the ink used in the background region. In the above-described embodiment 1, when the correction means 36 corrects the ink amount, the reduction amount of density in feature region Ar1 is set to be larger than that of feature region Ar2.

[0100] However, depending on the operation, the definitions of the line area (text area) and background area in feature areas Ar1 and Ar2 can be reversed. In other words, feature area Ar1 is defined as the area in the background area where there is color ink that is printed after the ink used in the line area (text area). Also, feature area Ar2 is defined as the area in the background area where there is color ink that is printed before the ink used in the line area (text area). Feature areas Ar1 and Ar2 can be set in this way. This setting can be achieved by swapping the definitions of the background area and line area (text area) in each item from the second to fifth rows of Figure 3, so that the background area is defined as the line area (text area) and the line area (text area) is defined as the background area. In this case, when the correction means 36 corrects the ink amount, it is preferable to set the reduction amount of the density of feature area Ar2 to be larger than that of feature area Ar1.

[0101] Furthermore, in the above-described embodiment 2, feature region Ar11 is defined as a region in the ink used in the line region (text region) that contains color ink printed after the ink used in the background region, and in a region in the ink used in the line region (text region) that does not contain the ink used in the background region. Also, feature region Ar12 is defined as a region in the ink used in the line region (text region) that contains color ink printed after the ink used in the background region, and in a region in the ink used in the line region (text region) that does contain the ink used in the background region. Also, feature region Ar21 is defined as a region in the ink used in the line region (text region) that contains color ink printed before the ink used in the background region, and in a region in the ink used in the line region (text region) that does not contain the ink used in the background region. Also, feature region Ar22 is defined as a region in the ink used in the line region (text region) that contains color ink printed before the ink used in the background region, and in a region in the ink used in the line region (text region) that does contain the ink used in the background region. In the above-described embodiment 2, when the correction means 36 corrects the amount of ink, it sets the reduction amount of density in feature region Ar11 to be greater than that of feature region Ar12, the reduction amount of density in feature region Ar21 to be greater than that of feature region Ar22, and the reduction amount of density in feature region Ar12 to be greater than that of feature region Ar22.

[0102] However, depending on the application, the definitions of the line area (text area) and background area can be reversed in feature areas Ar11, Ar12, Ar21, and Ar22. In other words, feature area Ar11 is an area in the background area where there is color ink that is printed after the ink used in the line area (text area), and where the ink used in the background area does not contain the ink used in the line area (text area). Feature area Ar12 is an area in the background area where there is color ink that is printed after the ink used in the line area (text area), and where the ink used in the background area does contain the ink used in the line area (text area). Feature area Ar21 is an area in the background area where there is color ink that is printed before the ink used in the line area (text area), and where the ink used in the background area does not contain the ink used in the line area (text area). Furthermore, feature area Ar22 is defined as an area in the background area where the ink used contains color ink that is printed before the ink used in the line area (text area), and where the ink used in the background area also contains the ink used in the line area (text area). Feature areas Ar11, Ar12, Ar21, and Ar22 can be set in this way. This setting can be achieved by swapping the definitions in each item from the second to fifth row of Figure 3, so that the background area is the line area (text area) and the line area (text area) is the background area. In this case, when the correction means 36 corrects the ink amount, it is preferable to set the reduction amount of density in feature area Ar12 to be greater than that of feature area Ar11, the reduction amount of density in feature area Ar22 to be greater than that of feature area Ar21, and the reduction amount of density in feature area Ar21 to be greater than that of feature area Ar11.

[0103] Furthermore, in the above-described Examples 1 and 2, the conditions for detecting each feature area may be increased to include the condition that the line area (text area) is composed of multiple ink colors, and the background area is composed of one or more ink colors. By doing so, even when the line area (text area) is used with three or more ink colors, and the amount of ink of each color is not large, areas with a large amount of bleeding can be efficiently detected.

[0104] Furthermore, in the above-described Examples 1 and 2, if the definitions of the line region (text region) and background region of the feature region are reversed, the conditions for detecting each feature region may be increased to include the condition that the background region is composed of multiple colors of ink, and the line region (text region) is composed of one or more colors of ink. By doing so, even when the background region is made up of three or more colors of ink, and the amount of ink of each color is not large, areas with a large amount of bleeding can be efficiently detected.

[0105] The calculation formula in this case can be as follows, for example. LINE_C = (Cin>LINEth)? 1:0 …(1) LINE_M = (Min>LINEth)? 1:0 …(2) LINE_Y = (Yin>LINEth)? 1:0 …(3) LINE_K = (Kin>LINEth)? 1:0 …(4) LINE_CMYK = (Cin+Min+Yin+Kin>LINE_CMYKth)? 1:0 …(5)

[0106] Equations (1) to (4) are as described above. The calculation formula in this case adds equation (5) to equations (1) to (4). Here, the part of equation (5) above, "LINE_CMYK = (Cin+Min+Yin+Kin>LINE_CMYKth) ?", is a determination formula to determine whether the sum of the CMYK data exceeds the threshold value of the ink color used in the line region (LINE_CMYKth). The part to the right of it, "1:0", indicates that if the determination formula is true (i.e., the sum of the CMYK data exceeds the threshold value of the ink color used in the line region (LINE_CMYKth)), the value will be "1", and if the determination formula is false (i.e., the sum of the CMYK data is less than or equal to the threshold value of the ink color used in the line region (LINE_CMYKth)), the value will be "0", and the value will be output accordingly.

[0107] Recording media (paper) can have properties that allow ink to penetrate quickly, or properties that make it difficult for ink to penetrate. Therefore, the inkjet recording device 100 may be configured to switch (set) a correction coefficient according to the recording media (paper). In this case, the inkjet recording device 100 may switch (set) a correction coefficient (hereinafter referred to as the "paper-dependent correction coefficient") according to the paper type selected by the user using the operation display unit 11 (see Figure 1) using the correction means 36 (see Figure 2). For example, the paper-dependent correction coefficient should be smaller for recording media (paper) that have properties that make it difficult for ink to penetrate (i.e., paper with low permeability and ink that easily bleeds) than for recording media (paper) that have properties that allow ink to penetrate quickly (i.e., paper with high permeability and ink that does not easily bleed). For example, if the recording medium (paper) has the characteristic of allowing ink to penetrate quickly (i.e., a paper type with high permeability and where ink does not easily bleed), the paper-dependent correction coefficient should be set to 1.0 (×1.0), and if the recording medium (paper) has the characteristic of not allowing ink to penetrate easily (i.e., a paper type with low permeability and where ink easily bleeds), the paper-dependent correction coefficient should be set to 0.9 (×0.9). The correction means 36 of the inkjet recording device 100 (see Figure 2) multiplies the image information (CMYK data) of each color included in the print command 61 (see Figure 2) by a correction coefficient for each feature area, and then further multiplies it by this paper-dependent correction coefficient.

[0108] <Main features of inkjet recording devices> (1) As shown in Figure 2, the inkjet recording apparatus 100 (color image forming apparatus) according to this embodiment includes a line area detection means 31 for detecting line areas, a background area detection means 32 for detecting background areas adjacent to line areas, a line area color detection means 33 for detecting the color of line areas, a background area color detection means 34 for detecting the color of background areas, a color comparison means 35 for comparing the color of line areas with the color of background areas, and a correction means 36 for correcting the amount of ink. The correction means 36 corrects the amount of ink at the boundary between line areas and background areas according to the combination pattern of ink colors of line areas and background areas determined by the color comparison by the color comparison means 35.

[0109] The inkjet recording apparatus 100 according to this embodiment can correct the amount of ink at the boundary between the line area and the background area in accordance with the difference in the amount of bleeding caused by the combination pattern of ink colors of the line area and the background area (i.e., the number of ink colors used in the line area (text area) and the background area, the order of impact, etc.). Therefore, it is possible to make it difficult for under-correction or over-correction to occur and to perform appropriate correction. As a result, ink bleeding at the boundary of images (lines and text) with a background can be reduced.

[0110] (2) In the inkjet recording apparatus 100 according to this embodiment, the area in the ink used in the line area in which there is color ink that is printed after the ink used in the background area is defined as feature area Ar1, and the area in the ink used in the line area in which there is color ink that is printed before the ink used in the background area is defined as feature area Ar2. The correction means 36 may correct the amount of ink in the feature area when it detects at least one of feature areas Ar1 or Ar2 by color comparison by the color comparison means 35.

[0111] In this embodiment of the inkjet recording apparatus 100, when feature regions Ar1 and Ar2 are detected, the amount of ink can be corrected according to the difference in the amount of bleeding caused by the number of ink colors, the order of ink impact, etc., in the feature regions Ar1 and Ar2. Therefore, undercorrection or overcorrection is less likely to occur, and appropriate correction can be performed. As a result, ink bleeding at the boundaries of images with a background (lines and characters) can be reduced.

[0112] (3) In the inkjet recording apparatus 100 according to this embodiment, the correction means 36 reduces the density of the feature region, and it is preferable to set the amount of density reduction for the feature region Ar1 to be greater than that for the feature region Ar2.

[0113] The inkjet recording apparatus 100 according to this embodiment can efficiently reduce ink bleeding at the boundaries of images (lines and characters) with a background.

[0114] (4) As explained in the above-mentioned Supplementary Chapter, if the definitions of the line region (character region) and the background region in the feature region are reversed, the region in the background region where there is color ink that is printed after the ink used in the line region will be defined as feature region Ar1, and the region in the background region where there is color ink that is printed before the ink used in the line region will be defined as feature region Ar2. The correction means 36 should correct the amount of ink in the feature region when it detects at least one of feature regions Ar1 or Ar2 by color comparison by the color comparison means 35.

[0115] The inkjet recording apparatus 100 according to this embodiment can efficiently reduce ink bleeding at the boundaries of images (lines and characters) with a background.

[0116] (5) As explained in the above-mentioned Supplementary Chapter, when the definitions of the line region (character region) and the background region in the feature region are reversed, in the inkjet recording apparatus 100 according to this embodiment, the correction means 36 reduces the density of the feature region, and sets the amount of density reduction for feature region Ar2 to be greater than that for feature region Ar1.

[0117] The inkjet recording apparatus 100 according to this embodiment can efficiently reduce ink bleeding at the boundaries of images (lines and characters) with a background.

[0118] (6) In the inkjet recording apparatus 100 according to this embodiment, a feature area Ar11 is defined as a region in the ink used in the line region where there is color ink that is printed after the ink used in the background region, and where the ink used in the line region does not contain the ink used in the background region; a feature area Ar12 is defined as a region in the ink used in the line region where there is color ink that is printed after the ink used in the background region, and where the ink used in the line region does contain the ink used in the background region; a feature area Ar21 is defined as a region in the ink used in the line region where there is color ink that is printed before the ink used in the background region, and where the ink used in the line region does not contain the ink used in the background region; and a feature area Ar22 is defined as a region in the ink used in the line region where there is color ink that is printed before the ink used in the background region, and where the ink used in the line region does contain the ink used in the background region. The correction means 36 may correct the amount of ink in the feature area when it detects at least one of the feature areas Ar11, Ar12, Ar21, or Ar22 by color comparison by the color comparison means 35.

[0119] In this embodiment of the inkjet recording apparatus 100, when feature regions Ar11, Ar12, Ar21, and Ar22 are detected, the amount of ink can be corrected according to the differences in the amount of bleeding caused by the number of ink colors, the order of ink impact, etc., in the feature regions Ar11, Ar12, Ar21, and Ar22. Therefore, undercorrection or overcorrection is less likely to occur, and appropriate correction can be performed. As a result, ink bleeding at the boundaries of images (lines and characters) with a background can be reduced.

[0120] (7) In the inkjet recording apparatus 100 according to this embodiment, the correction means 36 reduces the density of the feature region, and it is preferable to set the reduction amount of the density of feature region Ar11 to be greater than that of feature region Ar12, the reduction amount of the density of feature region Ar21 to be greater than that of feature region Ar22, and the reduction amount of the density of feature region Ar12 to be greater than that of feature region Ar22.

[0121] The inkjet recording apparatus 100 according to this embodiment can efficiently reduce ink bleeding at the boundaries of images (lines and characters) with a background.

[0122] (8) As explained in the above-mentioned Supplementary Chapter, if the definitions of the line region (character region) and the background region in the feature region are reversed, in the inkjet recording apparatus 100 according to this embodiment, the area in the background region where there is color ink that is printed after the ink used in the line region, and the area in the background region where there is no ink used in the line region, is defined as feature region Ar11, and the area in the background region where there is color ink that is printed after the ink used in the line region, and the area in the background region where there is ink used in the line region is defined as feature region Ar12, and back Feature region Ar21 is defined as an area in the background area where there is color ink printed before the ink used in the line area, and the ink used in the background area does not contain the ink used in the line area. Feature region Ar22 is defined as an area in the background area where there is color ink printed before the ink used in the line area, and the ink used in the background area contains the ink used in the line area. The correction means 36 should correct the amount of ink in the feature regions when it detects at least one of the feature regions Ar11, Ar12, Ar21, or Ar22 by color comparison by the color comparison means 35.

[0123] In this embodiment of the inkjet recording apparatus 100, when feature regions Ar11, Ar12, Ar21, and Ar22 are detected, the amount of ink can be corrected according to the differences in the amount of bleeding caused by the number of ink colors, the order of ink impact, etc., in the feature regions Ar11, Ar12, Ar21, and Ar22. Therefore, undercorrection or overcorrection is less likely to occur, and appropriate correction can be performed. As a result, ink bleeding at the boundaries of images (lines and characters) with a background can be reduced.

[0124] (9) As explained in the above-mentioned Supplementary Chapter, if the definitions of the line region (character region) and the background region in the feature region are reversed, in the inkjet recording apparatus 100 according to this embodiment, the correction means 36 reduces the density of the feature region, and it is preferable to set the reduction amount of the density of feature region Ar12 to be greater than that of feature region Ar11, the reduction amount of the density of feature region Ar22 to be greater than that of feature region Ar21, and the reduction amount of the density of feature region Ar21 to be greater than that of feature region Ar11.

[0125] The inkjet recording apparatus 100 according to this embodiment can efficiently reduce ink bleeding at the boundaries of images (lines and characters) with a background.

[0126] (10) In the inkjet recording apparatus 100 according to this embodiment, the line area may be composed of multiple colors of ink, and the background area may be composed of one or more colors of ink.

[0127] The inkjet recording apparatus 100 according to this embodiment can efficiently detect feature regions. Therefore, ink bleeding at the boundaries of images (lines and characters) with a background can be efficiently reduced.

[0128] (11) As explained in the above-mentioned Supplementary Chapter, if the definitions of the line region (character region) and the background region in the feature region are reversed, then in the inkjet recording apparatus 100 according to this embodiment, the line region is composed of one color of ink, and the background region is composed of multiple or more colors of ink.

[0129] The inkjet recording apparatus 100 according to this embodiment can efficiently detect feature regions. Therefore, ink bleeding at the boundaries of images (lines and characters) with a background can be efficiently reduced.

[0130] (12) In the inkjet recording apparatus 100 according to this embodiment, the line area may be composed of one or more colors of ink, with the total amount of ink being equal to or greater than a predetermined value.

[0131] The inkjet recording apparatus 100 according to this embodiment can efficiently detect feature regions. Therefore, ink bleeding at the boundaries of images (lines and characters) with a background can be efficiently reduced.

[0132] (13) As explained in the above-mentioned Supplementary Chapter, if the definitions of the line region (character region) and the background region in the feature region are reversed, then in the inkjet recording apparatus 100 according to this embodiment, the line region is composed of one or more inks, and the background region is such that the total amount of ink is equal to or greater than a predetermined value.

[0133] The inkjet recording apparatus 100 according to this embodiment can efficiently detect feature regions. Therefore, ink bleeding at the boundaries of images (lines and characters) with a background can be efficiently reduced.

[0134] (14) As explained in the above-mentioned Supplementary Chapter, in the inkjet recording apparatus 100 according to this embodiment, the correction means 36 may correct the amount of ink depending on the type of recording medium.

[0135] The correction means 36 of the inkjet recording apparatus 100 according to this embodiment can suitably correct the amount of ink at the boundary between the line area and the background area by multiplying the image information (CMYK data) of each color included in the print command 61 (see Figure 2) by a correction coefficient for each feature area, and then further multiplying it by a paper-dependent correction coefficient. As a result, ink bleeding at the boundary of images with a background (lines and characters) can be efficiently reduced.

[0136] (15) In the inkjet recording device 100 according to this embodiment, the corrected ink amount is obtained by multiplying the ink amount of the print command by a correction coefficient, and the correction coefficient for correcting the ink amount is preferably less than 1.0.

[0137] The inkjet recording apparatus 100 according to this embodiment can reduce the amount of ink at the boundary between the line area and the background area. Therefore, it can efficiently reduce ink bleeding at the boundary of an image with a background (lines or characters).

[0138] (16) The inkjet recording apparatus 100 according to this embodiment can realize the following inkjet recording method (color image forming method). That is, the inkjet recording method (color image forming method) comprises a line region detection step for detecting line regions, a background region detection step for detecting background regions adjacent to line regions, a line region color detection step for detecting the color of line regions, a background region color detection step for detecting the color of background regions, a color comparison step for comparing the color of line regions and the color of background regions, and a correction step for correcting the amount of ink, wherein in the correction step, the amount of ink is corrected according to the combination pattern of ink colors of line regions and background regions determined by the color comparison in the color comparison step.

[0139] The inkjet recording method according to this embodiment can correct the amount of ink at the boundary between the line area and the background area in accordance with the difference in the amount of bleeding caused by the combination pattern of ink colors in the line area and the background area (i.e., the number of ink colors used in the line area (text area) and the background area, the order of impact, etc.). Therefore, it is possible to make insufficient or overcorrection less likely and to perform appropriate correction. As a result, ink bleeding at the boundary of images (lines and text) with a background can be reduced.

[0140] As described above, the inkjet recording apparatus 100 (color image forming apparatus) according to this embodiment can reduce ink bleeding at the boundaries of images (lines and characters) with a background.

[0141] It should be noted that the present invention is not limited to the embodiments described above, and various modifications and variations can be made without departing from the spirit of the invention.

[0142] For example, the embodiments described above are explained in detail to make the gist of the present invention easier to understand. Therefore, the present invention is not necessarily limited to having all the components described. Furthermore, the present invention can be modified by adding other components to one component, or by changing some components to other components. Furthermore, the present invention can be modified by deleting some components. [Explanation of symbols]

[0143] 11 Operation display section 12 Image forming means 13 Communication I / F means 21 Control Unit 22 Memory section 31 Line region detection means 32 Background area detection means 33 Linear color detection means 34 Background area color detection means 35 Color comparison means 36 Correction means 51 Control Program 52 Correction Factor 53 Correction control table 61 Print command 62-bit map data 80 Recording media 81 First Color Ink 82 Second-color ink 83 Third-color ink 91 Smudge 100 Inkjet recording device (color image forming apparatus) Feature regions of Ar1, Ar2, Ar11, Ar12, Ar21, Ar22 Bk background area Ln line area

Claims

1. Line region detection means for detecting line regions, A background region detection means for detecting a background region adjacent to the aforementioned line region, A line region color detection means for detecting the color of the line region, A background region color detection means for detecting the color of the aforementioned background region, A color comparison means for comparing the color of the line region with the color of the background region, It includes a correction means for correcting the amount of ink, The correction means corrects the amount of ink according to the combination pattern of ink colors in the line region and background region determined by the color comparison by the color comparison means. Color image forming apparatus.

2. The region in the aforementioned line region that contains color inks that are printed later than the inks used in the aforementioned background region is defined as feature region Ar1. The region in the aforementioned line region where there is color ink that is printed before the ink used in the aforementioned background region is defined as feature region Ar2. The correction means corrects the amount of ink in the feature region when at least one of the feature regions Ar1 and Ar2 is detected by the color comparison by the color comparison means. The color image forming apparatus according to claim 1.

3. The correction means reduces the density of the feature region, and sets the amount of density reduction for feature region Ar1 to be greater than that for feature region Ar2. The color image forming apparatus according to claim 2.

4. The region in the background region where color inks are printed later than the inks used in the line region is defined as feature region Ar1. The region in the background region where there is color ink that is printed before the ink used in the line region is defined as feature region Ar2. The correction means corrects the amount of ink in the feature region when at least one of the feature regions Ar1 and Ar2 is detected by the color comparison by the color comparison means. The color image forming apparatus according to claim 1.

5. The correction means reduces the density of the feature region, and sets the reduction amount for the density of feature region Ar2 to be greater than that for feature region Ar1. The color image forming apparatus according to claim 4.

6. The feature region Ar11 is defined as a region in the line region where the ink used in the line region contains color inks that are printed after the ink used in the background region, and where the ink used in the line region does not contain the ink used in the background region. The feature region Ar12 is defined as a region in the line region where the ink used in the line region contains color ink that is printed after the ink used in the background region, and where the ink used in the line region also contains the ink used in the background region. The feature region Ar21 is defined as a region in the ink used in the line region that contains color ink printed before the ink used in the background region, and in a region in the ink used in the line region that does not contain the ink used in the background region. The feature region Ar22 is defined as a region in the ink used in the line region that contains color ink printed before the ink used in the background region, and in which the ink used in the line region includes the ink used in the background region. The correction means corrects the amount of ink in the feature region when at least one of the feature regions Ar11, Ar12, Ar21, and Ar22 is detected by the color comparison by the color comparison means. The color image forming apparatus according to claim 1.

7. The correction means reduces the density of the feature region, setting the reduction amount for feature region Ar11 to be greater than that for feature region Ar12, the reduction amount for feature region Ar21 to be greater than that for feature region Ar22, and the reduction amount for feature region Ar12 to be greater than that for feature region Ar22. The color image forming apparatus according to claim 6.

8. The feature region Ar11 is defined as a region in the background region where there are color inks that are printed after the inks used in the line region, and where the inks used in the background region do not include the inks used in the line region. The feature region Ar12 is defined as a region in the background region where the ink used contains color inks that are printed after the ink used in the line region, and where the ink used in the background region also contains the ink used in the line region. The feature region Ar21 is defined as a region in the background region where there is color ink printed before the ink used in the line region, and where the ink used in the background region does not include the ink used in the line region. The feature region Ar22 is defined as a region in the background region where the ink used in the background region contains color ink that is printed before the ink used in the line region, and where the ink used in the background region also contains the ink used in the line region. The correction means corrects the amount of ink in the feature region when at least one of the feature regions Ar11, Ar12, Ar21, and Ar22 is detected by the color comparison by the color comparison means. The color image forming apparatus according to claim 1.

9. The correction means reduces the density of the feature region, setting the reduction amount for feature region Ar12 to be greater than that for feature region Ar11, setting the reduction amount for feature region Ar22 to be greater than that for feature region Ar21, and setting the reduction amount for feature region Ar21 to be greater than that for feature region Ar11. The color image forming apparatus according to claim 8.

10. The aforementioned line region is composed of multiple colors of ink. The aforementioned background area is composed of one or more colors of ink. The color image forming apparatus according to claim 1.

11. The aforementioned line region is composed of one color of ink. The aforementioned background area is composed of multiple colors of ink. The color image forming apparatus according to claim 1.

12. The aforementioned line region is defined as having a total ink volume equal to or greater than a predetermined value. The aforementioned background area is composed of one or more colors of ink. The color image forming apparatus according to claim 1.

13. The aforementioned line region is composed of one or more colors of ink. The aforementioned background area is defined as having a total ink volume equal to or greater than a predetermined value. The color image forming apparatus according to claim 1.

14. The correction means corrects the amount of ink according to the type of recording medium. The color image forming apparatus according to claim 1.

15. The corrected ink quantity is obtained by multiplying the ink quantity specified in the print command by a correction factor. The correction factor for correcting the amount of ink is less than 1.

0. The color image forming apparatus according to claim 1.

16. A line region detection process for detecting a line region, A background region detection step for detecting a background region adjacent to the aforementioned line region, A line region color detection step for detecting the color of the line region, A background region color detection step for detecting the color of the background region, A color comparison step of comparing the color of the line region with the color of the background region, It includes a correction process for correcting the amount of ink, In the correction step, the amount of ink is corrected according to the combination pattern of ink colors in the line region and background region that was determined by the color comparison in the color comparison step. A method for forming a color image.

Images