Gradation reproduction
First Claim
1. A method for reproducing a gradation image of a plurality of colors comprising the steps of:
- receiving multi-level image data which represents gradation levels of an image to be reproduced;
selecting one of a plurality of patterns for a color of the received image data; and
screening the received image data with the selected pattern to generate bi-level image data for reproducing the image with dots, wherein the patterns include a first pattern making the dots in the reproduced image grow as lines as gradation level increases, and a second pattern making the dots in the reproduced image grow as lumps as gradation level increases.
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Accused Products
Abstract
In order to reproduce a gradation image of a plurality of colors with dither method, a plurality of patterns including first and second patterns are provided which makes dot in the reproduced image grow as lines and as lumps as gradation level increases with increase in gradation level. One of the patterns for a color of the received image data is selected, and received multi-level image data are screened with the selected pattern to generate bi-level image data for reproducing the image. In a different way, a plurality of patterns including first and second patterns are provided which make dots to be reproduced grow discretely along lines at low gradation levels as the gradation level increases. Screen angles of the first and second patterns are different by 90° from each other. One of the patterns is selected based on a color of received image data, and the received image data are screened with the selected patterns to generate bi-level image data. Thus, color shift or color nonuniformity in the reproduced image is suppressed, and image quality of full-color or multi-color reproduction image is improved.
26 Citations
20 Claims
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1. A method for reproducing a gradation image of a plurality of colors comprising the steps of:
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receiving multi-level image data which represents gradation levels of an image to be reproduced;
selecting one of a plurality of patterns for a color of the received image data; and
screening the received image data with the selected pattern to generate bi-level image data for reproducing the image with dots, wherein the patterns include a first pattern making the dots in the reproduced image grow as lines as gradation level increases, and a second pattern making the dots in the reproduced image grow as lumps as gradation level increases. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An image reproduction apparatus comprising:
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an input section receiving multi-level image data which represents gradation levels of an image to be reproduced;
a storage device storing patterns including a first pattern making dots in a reproduced image grow as lines as gradation level increases, and a second pattern making the dots in a reproduced image grow as lumps as gradation level increases;
a data processor selecting one of the patterns for a color of the received image data and screening the image data received by said input section with the selected pattern to generate bi-level image data; and
an image forming section which reproduces the image with dots according to the bi-level image data obtained by said data processor. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A storage device for storing data for access by an application program being executed by an image reproduction apparatus which reproduces a gradation image of a plurality of colors according to image data on the plurality of colors which represent gradation levels of the image reproduction apparatus, comprising data of a plurality of patterns for reproduction colors used to screen image data for conversion to bi-level dot data;
wherein the patterns include a first pattern making dots to be reproduced grow as lines as gradation level increases, and a second pattern making dots to be reproduced grow as lumps as gradation level increases. - View Dependent Claims (14, 15, 16, 17)
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18. A method for reproducing a gradation image, comprising the steps of:
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receiving multi-level image data which represents gradation levels of an image to be reproduced; and
screening the received image data with a gradation pattern to generate bi-level image data for reproducing the image with dots, wherein;
the gradation pattern makes dots to be reproduced appear discretely along lines at low gradation levels as the gradation level increases, the gradation pattern makes the discretely grown dots grow at intermediate gradation levels to form lines as the gradation level increases, and the gradation pattern makes dots appear in a direction crossing the lines at high gradation levels as the gradation level increases.
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19. An image reproduction apparatus comprising:
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an input section receiving multi-level image data which represents gradation levels of an image to be reproduced;
a storage device storing a pattern making dots to be reproduced appear discretely along lines at low gradation levels as the gradation level increases;
a data processor screening the image data received by said input section with the pattern to generate bi-level image data; and
an image forming section which reproduces the image with dots according to the bi-level image data obtained by said data processor, wherein;
the gradation pattern makes the discretely grown dots grow at intermediate gradation levels to form lines as the gradation level increases, and the gradation pattern makes dots appear in a direction crossing the lines at high gradation levels as the gradation level increases.
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20. A storage device for storing data for access by an application program being executed by an image reproduction apparatus which reproduces a gradation image according to image data which represent gradation levels of the image, comprising:
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data of a pattern used to screen image data for conversion to bi-level image data, wherein;
the pattern makes dots to be reproduced grow discretely along lines at low gradation levels as the gradation level increases, the gradation pattern makes the discretely grown dots grow as lines at intermediate gradation levels as the gradation level increases, and the gradation pattern makes dots appear in a direction crossing the lines at high gradation levels as the gradation level increases.
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Specification