Color image data compressing apparatus and method
First Claim
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1. A compressing apparatus for compressing color image data including R, G and B data, said apparatus comprising:
- a first converter for converting said R, G and B data into luminance data and chrominance data;
first encoder means for encoding said luminance data to compressed luminance data, through fine quantization at regions where human eyes are sensitive, and through coarse quantization at regions where human eyes are less sensitive; and
second encoder means for encoding said chrominance data to compressed chrominance data, through fine quantization at regions where human eyes are sensitive, and through coarse quantization at regions where human eyes are less sensitive;
said first encoder means comprising a first memory for storing a table for changing luminance data to compressed luminance data.
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Abstract
A compressing apparatus for compressing color image data including R, G and B data. The apparatus includes a converter for converting the R, G and B data into luminance data and chrominance data, and an encoder. The encoder encodes the luminance data to compressed luminance data, through fine quantization at regions where human eyes are sensitive, and through coarse quantization at regions where human eyes are less sensitive, such as, e.g., in dark or bright areas. The encoder also encodes the chrominance data to compressed chrominance data in a similar manner.
18 Citations
7 Claims
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1. A compressing apparatus for compressing color image data including R, G and B data, said apparatus comprising:
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a first converter for converting said R, G and B data into luminance data and chrominance data; first encoder means for encoding said luminance data to compressed luminance data, through fine quantization at regions where human eyes are sensitive, and through coarse quantization at regions where human eyes are less sensitive; and second encoder means for encoding said chrominance data to compressed chrominance data, through fine quantization at regions where human eyes are sensitive, and through coarse quantization at regions where human eyes are less sensitive; said first encoder means comprising a first memory for storing a table for changing luminance data to compressed luminance data. - View Dependent Claims (3, 4)
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2. A compressing apparatus for compressing color image data including R, G and B data, said apparatus comprising:
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a first converter for converting said R, G and B data into luminance data and chrominance data; first encoder means for encoding said luminance data to compressed luminance data, through fine quantization at regions where human eyes are sensitive, and through coarse quantization at regions where human eyes are less sensitive; and second encoder means for encoding said chrominance data to compressed chrominance data, through fine quantization at regions where human eyes are sensitive, and through coarse quantization at regions where human eyes are less sensitive; said second encoder means comprising a first memory for storing a table for changing chrominance data to compressed chrominance data. - View Dependent Claims (5)
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6. A compressing apparatus for compressing color image data including R, G and B data, said apparatus comprising:
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a first converter for converting said R, G and B data into luminance data and chrominance data; first encoder means for encoding said luminance data to compressed luminance data, through fine quantization at regions where human eyes are sensitive, and through coarse quantization at regions where human eyes are less sensitive; and second encoder means for encoding said chrominance data to compressed chrominance data, through fine quantization at regions where human eyes are sensitive, and through coarse quantization at regions where human eyes are less sensitive, and also through reducing the chrominance data word lengths by shortening the chrominance data word lengths when the magnitude of the luminance, as indicated by the luminance data, is above a predetermined first threshold or below a predetermined second threshold, wherein said predetermined first threshold is greater than said predetermined second threshold.
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7. A method for compressing color image data including R, G and B data, said method comprising steps of:
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converting said R, G and B data into luminance data and chrominance data; encoding said luminance data to compressed luminance data, through fine quantization at regions where human eyes are sensitive, and through coarse quantization at regions where human eyes are less sensitive; and encoding said chrominance data to compressed chrominance data, through fine quantization at regions where human eyes are sensitive, and through coarse quantization at regions where human eyes are less sensitive, and also through reducing the chrominance data word lengths by shortening the chrominance data word lengths when the magnitude of the luminance, as indicated by the luminance data, is above a predetermined first threshold or below a predetermined second threshold, wherein said predetermined first threshold is greater than said predetermined second threshold.
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Specification