Method and system for achieving coding gains in wavelet-based image codecs
First Claim
1. A method of encoding an image separated into a plurality of first color components of a first color space, wherein the first color components are converted into a plurality of second color components of a second color space different from the first color space, each of the second color components having a number of more-significant bit-planes and a first number of less-significant bit-planes, said encoding method comprising the steps of:
- adjusting the second color components by changing the first number of less-significant bit-planes of at least one of the second color components to a second number smaller than the first number;
transforming the adjusted second color components based on a forward wavelet transformation for providing transformed image data; and
coding the transformed image data for forming a bitstream indicative of the transformed image data.
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Accused Products
Abstract
A method and system for coding a RGB image in an encoder and a decoder. In the encoder, the RGB image components are converted into YUV components. One or more of the lower bit-planes of YUV components are eliminated before the YUV components are transformed by forward wavelet transform and coded into a codestream for transmission. In the decoder, the codestream is decoded and transformed by inverse wavelet transform into a set of reconstructed YUV components. The bit-planes of these reconstructed YUV components are up-shifted so that the up-shifted YUV components are structurally equivalent to the original YUV components before they are adjusted in the encoder. However, the lower bit-planes that come into being due to the up-shifting are all set to zero. The up-shifted YUV components are then converted into the RGB component of the reconstructed image.
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Citations
34 Claims
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1. A method of encoding an image separated into a plurality of first color components of a first color space, wherein the first color components are converted into a plurality of second color components of a second color space different from the first color space, each of the second color components having a number of more-significant bit-planes and a first number of less-significant bit-planes, said encoding method comprising the steps of:
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adjusting the second color components by changing the first number of less-significant bit-planes of at least one of the second color components to a second number smaller than the first number;
transforming the adjusted second color components based on a forward wavelet transformation for providing transformed image data; and
coding the transformed image data for forming a bitstream indicative of the transformed image data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 20, 21)
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12. An apparatus for encoding an image separated into a plurality of first color components of a first color space, wherein the first color components are converted into a plurality of second color components of a second color space different from the first color space, each of the second color components having a number of more-significant bit-planes and a first number of less-significant bit-planes, said apparatus comprising:
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means, responsive to the second color components, for adjusting from at least one of the second color components the first number of bit-planes to a second number smaller than the first number for providing adjusted second color components;
means for transforming the adjusted color components into transformed image data based on a forward wavelet transformation for providing a signal indicative of the transformed image data, and means, responsive to the signal, for coding the transformed image data and forming a bitstream indicative of the coded transformed image data.
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19. A software program for use in an encoder having transform means and coding means for processing image data indicative of an image into a bitstream, wherein the image is separated into a plurality of first color components of a first color space, and the first color components are converted into a plurality of second color components of a second color space different from the first color space, each of the second color components having a plurality of more-significant bit-planes and a first number of less-significant bit-planes, said software program comprising the steps of:
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adjusting, from at least one of the second color components, the first number of bit-planes to a second number smaller than the first number for providing adjusted second color components;
providing the adjusted second color components to the transform means so as to allow the transform means to transform the adjusted second color components based on a forward wavelet transformation into transformed image data, and the coding means to form the bitstream indicative of the transformed image data.
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22. An apparatus for processing a bitstream having coded data indicative of an image into a reconstructed image, wherein
the image is separated into a plurality of first color components of a first color space; -
the first color components are converted into a plurality of second color components of a second color space different from the first color space, each of the second color components having a first number of more-significant bit-planes and a second number of less-significant bit-planes;
the second color components are adjusted into adjusted second color components by changing, from at least one of the second color components, the second number of bit-planes to a corresponding third number smaller than the second number for providing adjusted second color components in the second color space;
the adjusted color components are transformed into transformed image data based on a forward wavelet transformation; and
the transformed data is coded into the bitstream having the coded data, said apparatus comprising;
means, responsive to the bitstream, for decoding the coded data for providing reconstructed transformed data;
means for processing the reconstructed transformed data based on an inverse wavelet transformation for providing first reconstructed color components in the second color space;
means for changing the first reconstructed color components into second reconstructed color components in the second color space, such that each of the second reconstructed color components has a number of more-significant bit-planes equal to the first number, and a number of less-significant bit-planes equal to the second number. - View Dependent Claims (23, 24, 25, 26, 27, 29, 30)
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28. A software program for use in an apparatus for processing a bitstream having coded data indicative of an image into a reconstructed image, wherein
the image is separated into a plurality of first color components of a first color space; -
the first color components are converted into a plurality of second color components of a second color space different from the first color space, each of the second color components having a first number of more-significant bit-planes and a second number of less-significant bit-planes;
the second color components are adjusted into adjusted second color components by changing, from at least one of the second color components, the second number of bit-planes to a corresponding third number smaller than the second number for providing adjusted second color components in the second color space;
the adjusted color components are transformed into transformed image data based on a forward wavelet transformation; and
the transformed data is coded into the bitstream having the coded data, said apparatus comprising;
means, responsive to the bitstream, for decoding the coded data for providing reconstructed transformed data;
means for processing the reconstructed transformed data based on an inverse wavelet transformation for providing first reconstructed color components in the second color space, each of the first reconstructed color components corresponding to one of the second color components, wherein each of the first reconstructed color components has a number of more-significant bit-planes equal to the first number, and a fourth number of less-significant number of bit-planes equal to the corresponding third number;
said software program comprising the steps of;
changing the first reconstructed color components into second reconstructed color components in the second color space, effectively adding a number of bit-planes to at least one of the first reconstructed color components corresponding to said at least one of the second color components such that each of the second reconstructed color components has a number of more-significant bit-planes equal to the first number, and a number of less-significant bit-planes equal to the second number; and
setting pixel values of the added bit-planes to zero.
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31. A system for coding an image into a bitstream and decoding the bitstream into a reconstructed image, wherein the image is separated into a plurality of first color components of a first color space, and the first color components are converted into a plurality of second color components of a second space different from the first color space, wherein each of the second color components has a first number of more-significant bit-planes and a second number of less-significant bit planes, said system comprising:
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means, responsive to the second color components, for adjusting at least one of the second color components the second number of bit-planes to a corresponding third number smaller than the second number for providing adjusted second color components in the second color space;
means for transforming the adjusted second color components into transformed image data based on a forward wavelet transformation for providing a signal indicative of the transformed image data;
means, responsive to the signal, for coding the transformed image data and forming a bitstream having coded information indicated of the coded transformed image data;
means, responsive to the bitstream, for decoding the coded information for providing reconstructed transformed data;
means for processing the reconstructed transformed data based on an inverse wavelet transformation for providing first reconstructed color components in the second color space; and
means for changing the first reconstructed color components into second reconstructed color components in the second color space indicative of the reconstructed image, such that each of the second reconstructed color components has a number of more-significant bit-planes equal to the first number, and a number of less-significant bit-planes equal to the second number. - View Dependent Claims (32, 33, 34)
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Specification