Image processing apparatus, image processing method, and program for performing halftone processing using a dithering matrix
AssigneeCanon Kabushiki Kaisha
InventorHirokazu Tamura
Life of this patent
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Abstract
An image processing apparatus which performs image processing for print processing, including: a pseudo halftone processing unit configured to perform pseudo halftone processing by dithering with respect to an input image, and generate a halftone image constituted by plural dots, and a threshold matrix holding unit configured to hold a threshold matrix used for the pseudo halftone processing, wherein in the threshold matrix, thresholds are arranged such that the halftone image has a density region in which dots to be formed depending on a density of the input image are not rotational symmetric on a 90° basis, and orientations of the dots differ from each other in the density region.
Claims11
An image forming apparatus comprising:
- a controlling portion having a processor which executes a set of instructions or having a circuitry, the controlling portion being configured to:
- perform halftone processing using a dithering matrix on input image data having multiple tones to output halftone image data;
- and
- rotate the output halftone image data by one of 90°, 180°, and 270°;
- wherein the dithering matrix includes a plurality of submatrices including a first submatrix and a second submatrix adjacent to the first submatrix,
- wherein threshold arrangement of the first submatrix is configured to output the halftone image data including a dot of a first shape when the halftone processing is performed on the input image data of a predetermined density,
- wherein threshold arrangement of the second submatrix is configured to output the halftone image data including a dot of a second shape when the halftone processing is performed on the input image data of the predetermined density, and
- wherein the second shape is different from the first shape, but is same as the first shape when the second shape is rotated by one of 90°, 180°, and 270°.
A method for performing halftone processing, the method comprising:
- performing halftone processing using a dithering matrix on input image data having multiple tones to output halftone image data;
- and
- rotating the output halftone image data by one of 90°, 180°, and 270°,
- wherein the dithering matrix includes a plurality of submatrices including a first submatrix and a second submatrix adjacent to the first submatrix,
- wherein threshold arrangement of the first submatrix is configured to output the halftone image data including a dot of a first shape when the halftone processing is performed on the input image data of a predetermined density,
- wherein threshold arrangement of the second submatrix is configured to output the halftone image data including a dot of a second shape when the halftone processing is performed on the input image data of the predetermined density, and
- wherein the second shape is different from the first shape, but is same as the first shape when the second shape is rotated by one of 90°, 180°, and 270°.
Dependencies are inferred from the claim text.