IMAGE DATA GENERATION METHOD, IMAGE RECORDING METHOD, IMAGE DATA GENERATION APPARATUS, AND IMAGE RECORDING APPARATUS
First Claim
1. An image data generation method of generating halftone image data through halftone processing performed on a multi-tone color image that includes images of a plurality of color components, the method comprising:
- a) performing halftone processing on each image of at least one color component among said plurality of color components to generate single-color halftone image data regarding each of said at least one color component, said single-color halftone image data indicating sizes of a plurality of dots that are respectively to be formed at a plurality of pixel positions that are arranged in a matrix in a halftone image region;
b) obtaining a hue of each pixel that corresponds to each pixel position in said color image, and in a case where the hue of said each pixel is within a first hue range, determining that a threshold dot size at said each pixel position for a target color component is a predetermined reference threshold dot size, said target color component being included in said plurality of color components and being one color component other than said at least one color component, and in a case where the hue of said each pixel is within a second hue range in which coloration of said target color component is stronger than in said first hue range, determining that said threshold dot size is a predetermined corrected threshold dot size that is larger than said reference threshold dot size; and
c) performing halftone processing on an image of said target color component with reference to the single-color halftone image data regarding said at least one color component to generate single-color halftone image data that indicates sizes of a plurality of dots of said target color component that are respectively to be formed at said plurality of pixel positions in said halftone image region, said operation c) including;
c1) performing halftone processing on one pixel in the image of said target color component and provisionally determining a size of a dot of said target color component that is to be formed at a pixel position corresponding to said one pixel;
c2) obtaining a total dot size that is a sum of a previous total dot size and a provisional dot size, said previous total dot size being a sum of sizes of dots of said at least one color component that are to be formed at said pixel position, and said provisional dot size being the size of the dot of said target color component that is provisionally determined in said operation c1);
c3) comparing said total dot size with a threshold dot size at said pixel position, and in a case where said total dot size is smaller than or equal to said threshold dot size, determining that the size of the dot of said target color component is a size equal to said provisional dot size, and in a case where said total dot size is larger than said threshold dot size, determining that the size of the dot of said target color component is a largest dot size that is within a range of a difference between said threshold dot size and said previous total dot size;
c4) in a case where said total dot size is larger than said threshold dot size in said operation c3), changing a pixel value of a group of neighboring pixels at one or more pixel positions that are located around said one pixel and at which the size of the dot of said target color component has not yet been determined, on the basis of a pixel value of said one pixel and a difference between said provisional dot size and the size of the dot of said target color component; and
c5) changing said one pixel to a next pixel in accordance with a predetermined processing order of said plurality of pixel positions and repeating said operations c1) to c4).
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Accused Products
Abstract
An image recording apparatus 1 generates halftone image data regarding black, cyan, magenta, and yellow from a multi-tone color image. Magenta is a target color component that has a lower ink density than that of the other color components. In generating halftone image data regarding magenta, the sum of the sizes of black, cyan, and magenta dots formed at a target pixel position is made smaller than or equal to a threshold dot size. If the hue of the pixel of interest is within a hue range in which magenta coloration is strong, it is determined that the threshold dot size is a corrected threshold dot size larger than the reference threshold dot size. It is thus possible to suppress overlapping of dots of a plurality of color components and to thereby improve color reproduction of the target color component while suppressing poor color reproduction and cockling.
2 Citations
23 Claims
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1. An image data generation method of generating halftone image data through halftone processing performed on a multi-tone color image that includes images of a plurality of color components, the method comprising:
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a) performing halftone processing on each image of at least one color component among said plurality of color components to generate single-color halftone image data regarding each of said at least one color component, said single-color halftone image data indicating sizes of a plurality of dots that are respectively to be formed at a plurality of pixel positions that are arranged in a matrix in a halftone image region; b) obtaining a hue of each pixel that corresponds to each pixel position in said color image, and in a case where the hue of said each pixel is within a first hue range, determining that a threshold dot size at said each pixel position for a target color component is a predetermined reference threshold dot size, said target color component being included in said plurality of color components and being one color component other than said at least one color component, and in a case where the hue of said each pixel is within a second hue range in which coloration of said target color component is stronger than in said first hue range, determining that said threshold dot size is a predetermined corrected threshold dot size that is larger than said reference threshold dot size; and c) performing halftone processing on an image of said target color component with reference to the single-color halftone image data regarding said at least one color component to generate single-color halftone image data that indicates sizes of a plurality of dots of said target color component that are respectively to be formed at said plurality of pixel positions in said halftone image region, said operation c) including; c1) performing halftone processing on one pixel in the image of said target color component and provisionally determining a size of a dot of said target color component that is to be formed at a pixel position corresponding to said one pixel; c2) obtaining a total dot size that is a sum of a previous total dot size and a provisional dot size, said previous total dot size being a sum of sizes of dots of said at least one color component that are to be formed at said pixel position, and said provisional dot size being the size of the dot of said target color component that is provisionally determined in said operation c1); c3) comparing said total dot size with a threshold dot size at said pixel position, and in a case where said total dot size is smaller than or equal to said threshold dot size, determining that the size of the dot of said target color component is a size equal to said provisional dot size, and in a case where said total dot size is larger than said threshold dot size, determining that the size of the dot of said target color component is a largest dot size that is within a range of a difference between said threshold dot size and said previous total dot size; c4) in a case where said total dot size is larger than said threshold dot size in said operation c3), changing a pixel value of a group of neighboring pixels at one or more pixel positions that are located around said one pixel and at which the size of the dot of said target color component has not yet been determined, on the basis of a pixel value of said one pixel and a difference between said provisional dot size and the size of the dot of said target color component; and c5) changing said one pixel to a next pixel in accordance with a predetermined processing order of said plurality of pixel positions and repeating said operations c1) to c4). - View Dependent Claims (2, 3, 4, 5, 6, 7, 13, 14)
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8. An image data generation method of generating halftone image data through halftone processing performed on a multi-tone color image that includes images of a plurality of color components, the method comprising:
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a) performing halftone processing on each image of at least one color component among said plurality of color components to generate single-color halftone image data regarding each of said at least one color component, said single-color halftone image data indicating sizes of a plurality of dots that are respectively to be formed at a plurality of pixel positions that are arranged in a matrix in a halftone image region; b) obtaining a hue of each pixel that corresponds to each pixel position in said color image, and in a case where the hue of said each pixel is within a first hue range, determining that a threshold dot size at said each pixel position for a target color component is a predetermined reference threshold dot size, said target color component being included in said plurality of color components and being one color component other than said at least one color component, and in a case where the hue of said each pixel is within a second hue range in which coloration of said target color component is stronger than in said first hue range, determining that said threshold dot size is a predetermined corrected threshold dot size that is larger than said reference threshold dot size; and c) performing halftone processing on an image of said target color component with reference to the single-color halftone image data regarding said at least one color component to generate single-color halftone image data that indicates sizes of a plurality of dots of said target color component that are respectively to be formed at said plurality of pixel positions in said halftone image region, said operation c) including; c1) performing halftone processing on the image of said target color component and provisionally determining sizes of said plurality of dots of said target color component that are respectively to be formed at said plurality of pixel positions in said halftone image region; c2) obtaining a total dot size that is a sum of a previous total dot size and a provisional dot size, said previous total dot size being a sum of sizes of dots of said at least one color component that are to be formed at a pixel position corresponding to one pixel in the image of said target color component, and said provisional dot size being the size of the dot of said target color component that is provisionally determined in said operation c1); c3) comparing said total dot size with a threshold dot size at said pixel position, and in a case where said total dot size is smaller than or equal to said threshold dot size, determining that the size of the dot of said target color component is a size equal to said provisional dot size, and in a case where said total dot size is larger than said threshold dot size, determining that the size of the dot of said target color component is a largest dot size that is within a range of a difference between said threshold dot size and said previous total dot size; c4) in a case where said total dot size is larger than said threshold dot size in said operation c3), changing a provisional dot size of a group of neighboring pixels at one or more pixel positions that are located around said one pixel and at which the size of the dot of said target color component has not yet been determined, on the basis of a difference between said provisional dot size of said one pixel of said target color component and the size of the dot of said target color component; and c5) changing said one pixel to a next pixel in accordance with a predetermined processing order of said plurality of pixel positions and repeating said operations c2) to c4). - View Dependent Claims (9, 10, 11, 12, 15)
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16. An image data generation apparatus for generating halftone image data through halftone processing performed on a multi-tone color image that includes images of a plurality of color components, the apparatus comprising:
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at least one single-color halftone image data generation part that performs halftone processing on an image of at least one color component among said plurality of color components to generate single-color halftone image data regarding each of said at least one color component, said single-color halftone image data indicating sizes of a plurality of dots that are respectively to be formed at a plurality of pixel positions that are arranged in a matrix in a halftone image region; a threshold dot size determination part that obtains a hue of each pixel that corresponds to each pixel position in said color image, and in a case where the hue of said each pixel is within a first hue range, determines that a threshold dot size at said each pixel position for a target color component is a predetermined reference threshold dot size, said target color component being included in said plurality of color components and being one color component other than said at least one color component, and in a case where the hue of said each pixel is within a second hue range in which coloration of said target color component is stronger than in said first hue range, determines that said threshold dot size is a predetermined corrected threshold dot size that is larger than said reference threshold dot size; and a target color component halftone image data generation part that performs halftone processing on an image of said target color component with reference to the single-color halftone image data regarding said at least one color component to generate single-color halftone image data that indicates sizes of a plurality of dots of said target color component that are respectively to be formed at said plurality of pixel positions in said halftone image region, said target color component halftone image data generation part including; a provisional size determination pan that performs halftone processing on one pixel in the image of said target color component and provisionally determines a size of a dot of said target color component that is to be formed at a pixel position corresponding to said one pixel; a dot size totaling part that obtains a total dot size that is a sum of a previous total dot size and a provisional dot size, said previous total dot size being a sum of sizes of dots of said at least one color component that are to be formed at said pixel position, and said provisional dot size being the size of the dot of said target color component that is provisionally determined by said provisional size determination part; a size determination part that compares said total dot size with a threshold dot size at said pixel position, and in a case where said total dot size is smaller than or equal to said threshold dot size, determines that the size of the dot of said target color component is a size equal to said provisional dot size, and in a ease where said total dot size is larger than said threshold dot size, determines that the size of the dot of said target color component is a largest dot size that is within a range of a difference between said threshold dot size and said previous total dot size; a pixel value changing part that, in a case where said total dot size is larger than said threshold dot size, changes a pixel value of a group of neighboring pixels at one or more pixel positions that are located around said one pixel and at which the size of the dot of said target color component has not yet been determined, on the basis of a pixel value of said one pixel and a difference between said provisional dot size and the size of the dot of said target color component; and a repetition control part that changes said one pixel to a next pixel in accordance with a predetermined processing order of said plurality of pixel positions and repeats the determination of said provisional dot size by said provisional size determination part, the calculation of said total dot size by said dot size totaling part, the determination of the size of the dot of said target color component by said size determination part, and the change of the pixel value by said pixel value changing part. - View Dependent Claims (18, 19, 20)
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17. An image data generation apparatus for generating halftone image data through halftone processing performed on a multi-tone color image that includes images of a plurality of color components, the apparatus comprising:
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at least one single-color halftone image data generation part that performs halftone processing on an image of at least one color component among said plurality of color components to generate single-color halftone image data regarding each of said at least one color component, said single-color halftone image data indicating sizes of a plurality of dots that are respectively to be formed at a plurality of pixel positions that are arranged in a matrix in a halftone image region; a threshold dot size determination part that obtains a hue of each pixel that corresponds to each pixel position in said color image, and in a case where the hue of said each pixel is within a first hue range, determines that a threshold dot size at said each pixel position for a target color component is a predetermined reference threshold dot size, said target color component being included in said plurality of color components and being one color component other than said at least one color component, and in a case where the hue of said each pixel is within a second hue range in which coloration of said target color component is stronger than in said first hue range, determines that said threshold dot size is a predetermined corrected threshold dot size that is larger than said reference threshold dot size; and a target color component halftone image data generation part that performs halftone processing on an image of said target color component with reference to the single-color halftone image data regarding said at least one color component to generate single-color halftone image data that indicates sizes of a plurality of dots of said target color component that are respectively to be formed at said plurality of pixel positions in said halftone image region, said target color component halftone image data generation part including; a provisional size determination part that performs halftone processing on the image of said target color component and provisionally determines sizes of said plurality of dots of said target color component that are respectively to be formed at said plurality of pixel positions in said halftone image region; a dot size totaling part that obtains a total dot size that is a sum of a previous total dot size and a provisional dot size, said previous total dot size being a sum of sizes of dots of said at least one color component that are to be formed at a pixel position corresponding to one pixel in the image of said target color component, and said provisional dot size being the size of the dot of said target color component that is provisionally determined by said provisional size determination part; a size determination part that compares said total dot size with a threshold dot size at said pixel position, and in a case where said total dot size is smaller than or equal to said threshold dot size, determines that the size of the dot of said target color component is a size equal to said provisional dot size, and in a case where said total dot size is larger than said threshold dot size, determines that the size of the dot of said target color component is a largest dot size that is within a range of a difference between said threshold dot size and said previous total dot size; a provisional size changing part that, in a case where said total dot size is larger than said threshold dot size, changes a provisional dot size of a group of neighboring pixels at one or more pixel positions that are located around said one pixel and at which the size of the dot of said target color component has not yet been determined, on the basis of a difference between said provisional dot size of said one pixel of said target color component and the size of the dot of said target color component; and a repetition control part that changes said one pixel to a next pixel in accordance with a predetermined processing order of said plurality of pixel positions and repeats the calculation of said total dot size by said dot size totaling part, the determination of the size of the dot of said target color component by said size determination part, and the change of the provisional dot size by said provisional size changing part. - View Dependent Claims (21, 22, 23)
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Specification