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US 6,154,493 AGranted
Compression of color images based on a 2-dimensional discrete wavelet transform yielding a perceptually lossless image
AssigneeIntel Corporation
InventorsTinku Acharya, Lina J. Karam, Francescomaria Marino
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Abstract
What is disclosed is a method that includes splitting raw image data into a plurality of channels including color plane difference channels, and then compressing separately each of these channels using a two-dimensional discrete wavelet transform, the compression utilizing quantization, whereby the recovery of the compressed channel data yielding a perceptually lossless image. The method and apparatus operates on images directly in their Bayer pattern form. Quantization thresholds are defined for the quantizing which may vary depending upon the channel and DWT sub-band being processed.
Claims28
A method comprising:
- splitting raw image data into a plurality of channels which include one or more color plane difference channels, the splitting includes arranging a first color plane of the raw image data into a first color channel and a second color channel, generating a first difference channel that differences said first color channel from values associated with a second color plane of the raw image data, and generating a second difference channel that differences said second color channel from values associated with a third color plane of the raw image data, said first color plane having twice the number of associated values as values associated with either said second or third color plane;
- and
- compressing separately each of said channels using a two-dimensional discrete wavelet transform, said compression utilizing quantization.
An apparatus for processing an image comprising:
- a channel generator configured to generate both color difference channels and color channels from said image by arranging a first color plane of the raw image data into a first color channel and second color channel, generating a first difference channel that differences said first color channel from values associated with a second color plane of the raw image data, and generating a second difference channel that differences said second color channel from values associated with a third color plane of the raw image data, said first color plane having twice the number of associated values as values associated with either said second or third color plane;
- and
- a compressor coupled to said channel generator to compress each channel generated by said channel generator using a two-dimensional discrete wavelet transform module (2-D DWT) for each channel.
A system comprising:
- an image processor, said processor configured to (1) split raw image data into a plurality of channels which include one or more color plane difference channels, by arranging a first color plane of the raw image data into a first color channel and second color channel, generating a first difference channel that differences said first color channel from values associated with a second color plane of the raw image data, and generating a second difference channel that differences said second color channel from values associated with a third color plane of the raw image data, said first color plane having twice the number of associated values as values associated with either said second or third color plane, and (2 compress said channels using quantization and discrete wavelet transforms;
- and
- an image memory coupled to said processor, said memory configured to store said compression channel data.
A system comprising:
- an optical subsystem configured to guide light;
- an image sensor positioned to receive the light and in response generate pixel values representative of said light, said pixel values to be stored as raw image data;
- an image processor coupled to the image sensor, said processor configured to split the raw image data into a plurality of channels which include one or more color plane difference channels, by arranging a first color plane of the raw image data into a first color channel and second color channel, generating a first difference channel that differences said first color channel from values associated with a second color plane of the raw image data, and generating a second difference channel that differences said second color channel from values associated with a third color plane of the raw image data, said first color plane having twice the number of associated values as values associated with either said second or third color plane, said processor being capable of compressing said channels using quantization and discrete wavelet transforms;
- and
- an image memory coupled to said processor to store said compression channel data.
2 more elements
A method comprising:
- reading compressed image data as a plurality of channels which includes one or more compressed color plane difference channels;
- decompressing separately each of said channels using a two-dimensional discrete wavelet transform to yield first and second difference channels of said decompressed image;
- and
- summing the first and second difference channels with values taken from separate color planes of the decompressed image to yield first and second color channels that together completely define another color plane of the decompressed image.
1 more element
An article comprising:
- a machine-readable medium containing instructions which when executed by a machine cause the machine to perform operations comprising
- splitting raw image data into a plurality of channels which includes one or more color plane difference channels, the splitting includes arranging a first color plane of the raw image data into a first color channel and a second color channel, generating a first difference channel that differences said first color channel from values associated with a second color plane of the raw image data, and generating a second difference channel that differences said second color channel from values associated with a third color plane of the raw image data, said first color plane having twice the number of associated values as values associated with either said second or third color plane, and
- compressing separately each of said channels using a two-dimensional discrete wavelet transform, said compression utilizing quantization.
An article comprising:
- a machine-readable medium containing instructions which when executed by a machine cause the machine to perform operations comprising
- reading compressed image data as a plurality of channels which includes one or more compressed color plane difference channels;
- decompressing separately each of said channels using a two-dimensional discrete wavelet transform to yield first and second difference channels of said decompressed image;
- and
- summing the first and second difference channels with values taken from separate color planes of the decompressed image to yield first and second color channels that together completely define another color plane of the decompressed image.
2 more elements
Dependencies are inferred from the claim text.