Systems and methods for moiré-reduced halftoning
First Claim
Patent Images
1. A moiré
- effect reduction system, comprising;
a halftone conversion circuit that converts an original image into a halftone image;
an output device modeling circuit that predicts a continuous-tone image from the halftone image;
an image comparison circuit that determines a feedback image based on the original image and the predicted continuous-tone image;
a filtering circuit that filters the feedback image to yield a filtered feedback image; and
an image mapping circuit that maintains an appropriate window based on a predetermined halftone screen, wherein the image comparison circuit compares the filtered feedback image and the original image to yield an adjusted image; and
the filter circuit and the image mapping circuit select a value of pixels neighboring a target pixel of the window to determine a center pixel value.
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Abstract
By using negative feedback, moiré patterns can be reduced, or virtually eliminated, from input black-and-white or color original images. In particular, by feeding back an image containing the difference between the original input image and the halftone output with possible moiré patterns, and subtracting the low-frequency part of this image from the original input image, a resultant halftone image can be achieved that has reduced moiré patterns.
23 Citations
27 Claims
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1. A moiré
- effect reduction system, comprising;
a halftone conversion circuit that converts an original image into a halftone image;
an output device modeling circuit that predicts a continuous-tone image from the halftone image;
an image comparison circuit that determines a feedback image based on the original image and the predicted continuous-tone image;
a filtering circuit that filters the feedback image to yield a filtered feedback image; and
an image mapping circuit that maintains an appropriate window based on a predetermined halftone screen, wherein the image comparison circuit compares the filtered feedback image and the original image to yield an adjusted image; and
the filter circuit and the image mapping circuit select a value of pixels neighboring a target pixel of the window to determine a center pixel value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- effect reduction system, comprising;
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8. A method for reducing moiré
- effects in a previously halftoned image, comprising;
converting an original image into a halftone image;
predicting a predicted image based on the halftone image;
comparing the original image to the predicted image to yield a feedback image by an image comparison circuit;
filtering the feedback image;
maintaining an appropriate window based on a predetermined halftone screen;
selecting a value of pixels neighboring a target pixel of the window to determine a center pixel value by a filter circuit and an image mapping circuit, comparing the filtered feedback image to the original image to yield an adjusted image by the image comparison circuit; and
converting the adjusted image into a halftone output image. - View Dependent Claims (9, 10, 11, 12, 13)
- effects in a previously halftoned image, comprising;
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14. A moiré
- effect reduction system for an original device-independent image, comprising;
an image mapping circuit that converts the original device-independent image into a device-dependent image;
a halftone conversion circuit that converts the device-dependent image into a halftone image;
an output device modeling circuit that predicts a device-independent image from the halftone image;
an image comparison circuit that compares the original device-independent image to the predicted device-independent image to yield a feedback image;
a filtering circuit that filters the feedback image to yield a filtered feedback image; and
an image mapping circuit that maintains an appropriate window based on a predetermined halftone screen, wherein the image comparison circuit compares the filtered feedback image and the original device-independent image to yield an adjusted image, and the filter circuit and the image mapping circuit select a value of pixels neighboring a target pixel of the window to determine a center pixel value. - View Dependent Claims (15, 16, 17, 18, 19, 20)
- effect reduction system for an original device-independent image, comprising;
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21. A method for reducing moiré
- effects in a previously halftoned image, comprising;
converting an original device-independent image into a device-dependent image;
converting the device-dependent image into a halftone image;
predicting a predicted device-independent image based on the halftone image;
comparing the original device-independent image to the predicted device-independent image to yield a feedback image by an image comparison circuit;
filtering the feedback image;
maintaining an appropriate window based on a predetermined halftone screen;
selecting a value of pixels neighboring a target pixel of the window to determine a center pixel value by a filter circuit and an image mapping circuit, comparing the filtered feedback image to the original device-independent image to yield an adjusted image by the image comparison circuit; and
converting the adjusted image into a halftone output image. - View Dependent Claims (22, 23, 24, 25, 26, 27)
- effects in a previously halftoned image, comprising;
Specification