Method and system for compressing color video data
First Claim
1. A method for compressing color video data in a video communication system having means for producing a color video signal for a plurality of video picture frames, with each picture frame comprising a plurality of scan lines composed of a plurality of pixels, each scan line having a starting pixel and an ending pixel, and each pixel in each said frame comprising three digital color component signals of first, second and third digital word sizes, respectively, said method comprising the steps of:
- (a) determining a luminance function for each pixel based upon at least one of said three digital color component signals;
(b) determining at least one decision parameter for at least a substantial portion of the pixels in the scan lines of said picture frame based upon the difference of said luminance function between pixels at least one predetermined distance from at least one other pixel on each scan line;
(c) determining the rate of change of said at least one decision parameter for each of said pixels for which said luminance function difference has been determined;
(d) comparing said rate of change of said at least one decision parameter with a corresponding adaptive rate of change threshold to determine which of said pixels represent decision points;
(e) reducing the word size of at least one of said three digital color components signals to provide one to three reduced digital color component signals of fourth, fifth, and sixth digital word sizes, respectively, for each said pixel; and
(f) coding said plurality of pixels in each scan line as a plurality of combinations of pixel run lengths and said three reduced color component signals for each said run length, said run lengths being determined between said starting pixel for each scan line, intermediate points selected from the group of said decision points and points intermediate said decision points, and said ending pixel, and each run length being of a seventh digital word size.
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Abstract
The method and system for compressing color video data in a video communication system utilizes a three color digital signal, and involves the determination of a luminance function for each pixel in a series of video picture frames. One or more decision parameters based upon differences of the luminance function between pixels are compared with corresponding adaptive thresholds to determine decision points in the scan lines, and the digital word size of the three digital color components is reduced before encoding of run lengths between decision points of the color values.
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Citations
57 Claims
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1. A method for compressing color video data in a video communication system having means for producing a color video signal for a plurality of video picture frames, with each picture frame comprising a plurality of scan lines composed of a plurality of pixels, each scan line having a starting pixel and an ending pixel, and each pixel in each said frame comprising three digital color component signals of first, second and third digital word sizes, respectively, said method comprising the steps of:
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(a) determining a luminance function for each pixel based upon at least one of said three digital color component signals; (b) determining at least one decision parameter for at least a substantial portion of the pixels in the scan lines of said picture frame based upon the difference of said luminance function between pixels at least one predetermined distance from at least one other pixel on each scan line; (c) determining the rate of change of said at least one decision parameter for each of said pixels for which said luminance function difference has been determined; (d) comparing said rate of change of said at least one decision parameter with a corresponding adaptive rate of change threshold to determine which of said pixels represent decision points; (e) reducing the word size of at least one of said three digital color components signals to provide one to three reduced digital color component signals of fourth, fifth, and sixth digital word sizes, respectively, for each said pixel; and (f) coding said plurality of pixels in each scan line as a plurality of combinations of pixel run lengths and said three reduced color component signals for each said run length, said run lengths being determined between said starting pixel for each scan line, intermediate points selected from the group of said decision points and points intermediate said decision points, and said ending pixel, and each run length being of a seventh digital word size. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A system for compressing color video data for use in a video communication system having means for producing a color video signal for a plurality of video picture frames, with each picture frame comprising a plurality of scan lines composed of a plurality of pixels, each scan line having a staring pixel and an ending pixel, and each pixel in said frame comprising three digital color component signals of first, second and third digital word sizes, respectively, said system comprising:
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(a) means for determining a luminance function for each pixel based upon at least one of said three digital color component signals; (b) means for determining at least one decision parameter for at least a substantial portion of the pixels in the scan lines of said picture frame based upon the difference of said luminance function between pixels at least one predetermined distance from at least one other pixel on each scan line; (c) means for determining the rates of change of said at least one decision parameter for each of said pixels for which said luminance function difference has been determined; (d) means for comparing said rate of change of said at least one decision parameter with a corresponding adapative rate of change threshold to determine which of said pixels represent decision points; (e) means for reducing the word size of at least one of said three digital color components signals to provide one to three reduced digital color component signals of fourth, fifth, and sixth digital word sizes, respectively, for each said pixel; (f) means for coding said plurality of pixels in each scan line as a plurality of combinations of pixel run lengths and said three reduced color component signals for each said run length, said run lengths being determined between said starting pixel for each scan line, intermediate points selected from the group of said decision points and points intermediate said decision points, and said ending pixel, and each run length being of a seventh digital word size. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. In a camera for use in a video communication system, said camera being of the type producing a color video signal for a plurality of video picture frames, with each picture frame comprising a plurality of scan lines composed of a plurality of pixels, each scan line having a starting pixel and an ending pixel, and each pixel in said frame comprising three digital color component signals of first, second and third digital word sizes, respectively, the improvement in said camera comprising:
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(a) means for determining a luminance function for each pixel based upon at least one of said three digital color component signals; (b) means for determining at least one decision parameter for at least a substantial portion of the pixels in the scan lines of said picture frame based upon the difference of said luminance function between pixels at least one predetermined distance from at least one other pixel on each scan line; (c) means for determining the rate of change of said at least one decision parameter for each of said pixels for which said luminance function difference has been determined; (d) means for comparing said rate of change of said at least one decision parameters with a corresponding adaptive rate of change threshold to determine which of said pixels represent decision points; (e) means for reducing the word size of at least one of said three reduced digital color components signals to provide one to three reduced digital color component signals of fourth, fifth, and sixth digital word sizes, respectively, for each said pixel; (f) means for coding said plurality of pixels in each scan line as a plurality of combinations of pixel run lengths and said three reduced color component signals for each said run length, said run lengths being determined between said starting pixel for each scan line, intermediate points selected from the group of said decision points and points intermediate said decision points, and said ending pixel, and each run length being of a seventh digital word size. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57)
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Specification