Method including lossless compression of luminance channel and lossy compression of chrominance channels
AssigneeHewlett-Packard Development Company, L.P.
InventorsRon P. Maurer, Danny Barash, Richard Alan Burgin, David E. Thedens
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Abstract
Compression of a digital image is performed by bit-depth truncating a luminance channel of the digital image and performing lossless compression on the bit-depth truncated luminance channel; and performing lossy compression on chrominance channels of the digital image.
Claims27
A method of compressing a digital image, the method comprising:
- truncating bit depth of a luminance channel of the digital image and performing lossless compression on the truncated luminance channel;
- and
- performing lossy compression on chrominance channels of the digital image;
- wherein the bit truncation and lossless compression cause a loss of dynamic accuracy but not spatial accuracy in the luminance channel;
- and
- wherein the lossy compression causes a loss of spatial accuracy but not dynamic accuracy in the chrominance channels.
A method of compressing a digital image, the method comprising:
- truncating bit depth of a luminance channel of the digital image and performing lossless compression on the truncated luminance channel;
- and
- performing lossy compression on chrominance channels of the digital image;
- wherein the bit depth of the luminance channel is truncated to between five and seven bits.
A method of compressing a digital image, the method comprising:
- performing denoising and sharpening of the luminance channel;
- truncating bit depth of the denoised and sharpened luminance channel;
- performing lossless compression on the truncated luminance channel;
- and
- performing lossy compression on chrominance channels of the digital image.
A method of compressing a digital image, the method comprising:
- truncating bit depth of a luminance channel of the digital image and performing lossless compression on the truncated luminance channel, the lossless compression producing a first compressed data stream;
- performing lossy compression on chrominance channels of the digital image, the lossy compression producing second and third compressed data streams;
- and
- combining the first, second and third streams into a single file.
A method of reconstructing a digital image from a file, the method comprising:
- extracting from the file a first stream of compressed bit-depth truncated luminance information and second and third streams of compressed chrominance information;
- using lossless decompression to reconstruct a luminance channel from the first stream;
- using lossy decompression to reconstruct chrominance channels from the second and third streams;
- and
- processing the reconstructed chrominance channels to reduce chromatic bleeding artifacts if the chrominance information was downsampled during compression.
Apparatus for compressing a digital image, the apparatus comprising a processor for bit-depth truncating a luminance channel of the image and performing lossless compression on the bit-depth truncated channel, and performing lossy compression on chrominance channels of the digital image, the bit truncation and lossless compression causing a loss of dynamic accuracy but not spatial accuracy in the luminance channel, the lossy compression causing a loss of spatial accuracy but not dynamic accuracy in the chrominance channels.
Apparatus for compressing a digital image, the apparatus comprising a processor for bit-depth truncating raw values in a luminance channel of the image and performing lossless compression on the bit-depth truncated channel, the bit depth of the luminance channel truncated to between five and seven bits.
Apparatus for compressing a digital image, the apparatus comprising a processor for performing denoising and sharpening of a luminance channel of the digital image, bit-depth truncating the denoised and sharpened luminance channel, and performing lossless compression on the bit-depth truncated luminance channel.
Apparatus for reconstructing an image from a file, the apparatus comprising a processor for extracting a first stream of compressed bit-depth truncated luminance information and second and third streams of compressed chrominance information from the file;
- using lossless decompression to reconstruct a luminance channel from the first stream;
- using lossy decompression to reconstruct chrominance channels from the second and third streams;
- and processing the reconstructed chrominance channels to reduce chromatic bleeding artifacts if the chrominance information was downsampled during compression.
An article for a processor, the article comprising computer memory;
- and a program stored in the memory, the program, when executed, causing the processor to perform at least one of:
- image compression by bit-depth truncating a luminance channel of a digital image and compressing the bit-depth truncated luminance channel according to a lossless compression algorithm, and compressing chrominance channels of the digital image according to a lossy compression algorithm, wherein the bit truncation and lossless compression cause a loss of dynamic accuracy but not spatial accuracy in the luminance channel;
- and wherein the lossy compression causes a loss of spatial accuracy but not dynamic accuracy in the chrominance channels;
- and
- image reconstruction by extracting a first stream of bit-depth truncated compressed luminance information and second and third streams of compressed chrominance information;
- using lossless decompression to reconstruct a luminance channel from the first stream;
- using lossy decompression to reconstruct chrominance channels from the second and third streams;
- and processing the reconstructed chrominance channels to reduce chromatic bleeding artifacts if the chrominance information was downsampled during compression.
Dependencies are inferred from the claim text.