Mixed screen frequencies with image segmentation
First Claim
1. Apparatus for producing a screened halftone image of continuous tone original images, said apparatus comprising:
- means for producing a series of input signals whose values are representative of the gray levels of successive picture elements of an original image;
means for examining each pixel for an image characteristic and (1) means for classifying pixels by said image characteristic and (2) means for grouping pixels having the same classification to form segmented regions; and
means for printing groups of sub-elements sequentially organized into two dimensional matrix halftone cells, each halftone cell being associated with one of said input signals;
said printing means being adapted to print halftone cells associated with one of said segmented regions at a first screen frequency and to print halftone cells associated with another of said segmented regions at a second screen frequency higher than said first screen frequency.
1 Assignment
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Accused Products
Abstract
Apparatus for producing a screen halftone image provides for segmentation of images by optical density, busyness, segment size, and/or propensity to contouring; and for printing the segments which have high optical density, are more busy, and/or have a lesser propensity to contouring at a relatively high screen frequency; and for printing segments which have low optical density, are less busy, and/or have a greater propensity to contouring at a relatively low screen frequency. Both screen frequencies are printed at the same apparent screen angle to reduce texturing. Small segments are assigned the same screen frequency as the surrounding segment.
35 Citations
24 Claims
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1. Apparatus for producing a screened halftone image of continuous tone original images, said apparatus comprising:
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means for producing a series of input signals whose values are representative of the gray levels of successive picture elements of an original image; means for examining each pixel for an image characteristic and (1) means for classifying pixels by said image characteristic and (2) means for grouping pixels having the same classification to form segmented regions; and means for printing groups of sub-elements sequentially organized into two dimensional matrix halftone cells, each halftone cell being associated with one of said input signals;
said printing means being adapted to print halftone cells associated with one of said segmented regions at a first screen frequency and to print halftone cells associated with another of said segmented regions at a second screen frequency higher than said first screen frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for producing a screened halftone image of continuous-tone original images, said apparatus comprising:
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means for producing a series of input signals whose values are representative of the gray levels of successive picture elements of an original image; means for segmenting the original image into at least two regions of different image characteristics, said segmenting means including means for examining each pixel for an image characteristic and (1) means for classifying pixels by said image characteristic and (2) means for grouping pixels having the same classification to form a region; means for printing groups of sub-elements sequentially organized into two dimensional matrix halftone cells which have substantially the same apparent screen angle, each halftone cell being associated with one of said input signals;
said printing means being adapted to print halftone cells associated with one of said segmented regions at a first screen frequency and to print halftone cells associated with the other of said segmented regions at a second screen frequency higher than said first screen frequency. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method for producing a screened halftone image of continuous-tone original images, said method comprising the steps of:
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generating a series of input signals whose values are representative of the grey levels of successive picture elements of an original image; segmenting the original image into at least two regions of different image characteristics, said step of segmenting including examining each pixel for an image characteristic and (1) classifying pixels by said image characteristic and (2) grouping pixels having the same classification to form a region; printing groups of sub-elements sequentially organized into two dimensional matrix halftone cells, each halftone cell being associated with one of said input signals and wherein halftone cells associated with one of said segmented regions are printed at a first screen frequency and halftone cells associated with the other of said segmented regions are printed at a second screen frequency higher than said first screen frequency. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification