Method and apparatus for halftoning and inverse halftoning and the transmission of such images
First Claim
1. A method for the inverse-halftoning of dot and dispersed dot halftones, comprising the steps of:
- adaptive run-length filtering over at least one of rows and columns and diagonals of said halftones and combining the run-length estimates into an averaged continuous tone image;
filtering said averaged continuous tone image; and
removing any impulses and periodicities remaining in the filtered averaged continuous tone image.
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Accused Products
Abstract
A method of and system for rendering a halftone image of a gray scale image by utilizing a pixel-by-pixel comparison of the gray scale image against a blue noise mask is disclosed in which the gray scale image is scanned on a pixel-by-pixel basis and compared on a pixel-by-pixel basis to an array of corresponding data points contained in a blue noise mask stored in a PROM or computer memory in order to produce the desired halftoned image. Both digital and optically implemented halftone methods are disclosed. A method for obtaining the inverse halftone or gray scale image of a halftone image is also disclosed in which the halftone image can be comprised of clustered dots or dispersed dots, and it is not necessary to have knowledge of the screening methods or parameter. A method for transmitting and receiving a gray scale image in a compressed and decompressed manner, respectively, is disclosed for efficient facsimile transmission of images.
94 Citations
29 Claims
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1. A method for the inverse-halftoning of dot and dispersed dot halftones, comprising the steps of:
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adaptive run-length filtering over at least one of rows and columns and diagonals of said halftones and combining the run-length estimates into an averaged continuous tone image; filtering said averaged continuous tone image; and removing any impulses and periodicities remaining in the filtered averaged continuous tone image. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for the inverse-halftoning of dispersed dot and dispersed dot halftones, comprising the steps of:
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adaptive run-length filtering over rows and columns and diagonals of said halftones and combining the run-length estimates into an averaged continuous tone image; removing any impulses and periodicities remaining in the filtered averaged continuous tone image; and dynamically remapping said averaged continuous tone image after removing any impulses and periodicities to produce an inverse-halftone image. - View Dependent Claims (8)
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9. A method for the inverse-halftoning of dispersed dot and dispersed dot halftones, comprising the steps of:
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adaptive run-length filtering over rows and columns and diagonals of said halftones and combining the run-length estimates into an averaged continuous tone image; filtering said averaged continuous tone image; and dynamically remapping said filtered averaged continuous tone image to produce an inverse-halftoning image. - View Dependent Claims (10)
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11. A method for the inverse-halftoning of dispersed dot and dispersed dot halftones, comprising the steps of:
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generating a halftone image of said continuous tone image to be encoded using a predetermined halftone screen; subdividing said continuous tone image into blocks having a predetermined size; calculating a local mean continuous tone image for each of said blocks; generating a mean halftone image for each of said calculated local mean continuous tone images using said predetermined halftone screen; and generating an error image by obtaining the difference between said halftone image and said mean halftone image. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for the transmitting and receiving of a continuous tone image, comprising the steps of:
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encoding said continuous tone image using a predetermined halftone screen; transmitting said encoded continuous tone image; receiving said encoded continuous tone image; and decoding said encoded continuous tone image using said predetermined halftone screen to reproduce said continuous tone image. - View Dependent Claims (22, 23, 24, 25)
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26. A system for transmitting and receiving a halftone image, comprising:
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a first facsimile device having a memory in which a predetermined halftone screen is stored; means contained in said first facsimile device for encoding said halftone image and for transmitting said encoded halftone image; a second facsimile device having a memory in which said predetermined halftone screen is stored; and means contained in said second facsimile device for receiving said transmitted encoded halftone image and for decoding said received encoded halftone image. - View Dependent Claims (27, 28)
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29. A method for encoding and decoding a digital image, comprising the steps of:
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halftoning said digital image using a blue noise mask; encoding said halftoned digital image; transmitting said encoded halftoned digital image; receiving said encoded halftoned digital image; decoding said encoded halftoned digital image using said blue noise mask to reproduce said halftoned digital image; and inverse-halftoning said halftoned digital image to reproduce said digital image.
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Specification