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US 2001/0043754 A1Published application
Variable quantization compression for improved perceptual quality
OwnerNasir Memon, Daniel R. Tretterinventors
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OwnerNasir Memon, Daniel R. Tretterinventors
Estimating the term…
A process and apparatus is described to improve the fidelity of compressed images by computing a scaling value for each block based on a perceptual classification performed in the spatial domain. This provides a computationally simple way to reduce artifacts by computing appropriate block-variable scale factors for the quantization tables used in frequency domain-based compression schemes such as the the JPEG compression standard. Because a scale factor for a block is determined based on computations performed in the spatial domain, such computations can be made in parallel with the Discrete Cosine Transform (DCT) computation, thereby providing the same throughput in hardware or parallel processing software as can be obtained by baseline JPEG.
A compression process for a spatial domain digital image having a plurality of blocks, the process comprising the steps of:
The process as set forth in 1, comprising the step of entropy coding the scaled quantized frequency domain blocks resulting in step d).
A compression processor for a spatial domain digital image having a plurality of blocks, the processor comprising:
The processor as set forth in 8, comprising a coder to entropy code the scaled quantized frequency domain blocks from the quantizer.
A digital imaging system, comprising:
A digital imaging system, comprising:
The system as set forth in 16, comprising an output device to output the decompressed image.
Dependencies are inferred from the claim text.