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US 12,113,989 B2Granted
Lossless decompression of digital images using prior image context
AssigneeDropbox, Inc.
InventorsDaniel Horn, Ken Elkabany, Keith Winstein
Life of this patent
Estimating the term…
Abstract
Techniques for lossless compression of a digital image using prior image context.
Claims20
A method of recovering compressed digital images from further compressed image data, the method comprising:
- identifying further compressed image data corresponding to an original compressed digital image;
- determining, from the further compressed image data, a plurality of quantized AC coefficients of a target block of discrete cosine transform (DCT) coefficients corresponding to the original compressed digital image;
- determining a DC coefficient for the target block based on the plurality of quantized AC coefficients and at least one neighboring block of DCT coefficients that borders the target block;
- and
- generating the original compressed digital image based on the plurality of quantized AC coefficients and the DC coefficient.
2 more elements
A non-transitory computer-readable medium storing executable instructions that, when executed by at least one processor, cause a computing device to:
- identify compressed image data corresponding to an original digital image;
- determine, from the compressed image data, a plurality of AC coefficients of a target block of discrete cosine transform (DCT) coefficients corresponding to the original digital image;
- determine a DC coefficient for the target block based on the plurality of AC coefficients and at least one neighboring block of DCT coefficients that borders the target block;
- and
- generate the original digital image based on the plurality of AC coefficients and the DC coefficient.
2 more elements
A system comprising:
- at least one processor:
- at least one non-transitory computer readable medium storing instruction thereon that, when executed by the at least one processor, cause the system to:
- identify further compressed image data corresponding to an original compressed digital image;
- determine, from the further compressed image data, a plurality of frequency-space coefficients of a target block corresponding to the original compressed digital image;
- determine an average-value coefficient for the target block based on the plurality of frequency-space coefficients of the target block and at least one neighboring block of frequency-space coefficients that border the target block;
- and
- generate the original compressed digital image based on the plurality of frequency-space coefficients and the average-value coefficient.
4 more elements
Dependencies are inferred from the claim text.