Lead Inventors: Kannan Ramchandran, PhD, Martin Vetterli, PhD, Yanbin Yu PhD,
Dimitris Anastassiou, PhD
Maintaining JPEG and MPEG Decoder Compatibility
Good compression when using JPEG and MPEG decoders results from determining an optimal thresholding strategy for the DCT (discrete cosine transform) coefficients. Thresholding, or dropping, the less significant DCT coefficients, while having a marginally negative impact on coded quality, could result in a significant reduction in coding bit rate as fewer coefficients would need to be transmitted. However, determining which DCT coefficients to drop and maintain decoder compatibility can be problematic.
Algorithm Uses Dynamic Programming Recursive Structure to Maintain JPEG and MPEG Compatibility
The technology comprises an optimal algorithm that uses a fast dynamic programming recursive structure. This novel low complexity dynamic programming method exploits the ‘monotonic’ nature of bit rate versus zero run-length characteristics of JPEG and MPEG standards.
Applications:
The optimization of delivered coding quality and signal-to-noise ratio for JPEG and MPEG while maintaining compatibility with existing decoders.
Advantages:
Optimizes the encoder thresholding operation while maintaining compatibility with standard JPEG and MPEG decoders.
Patent Status: Issued Patent
US 5,734,755
Publications:
http://www.eecs.berkeley.edu/~kannanr/
http://lcavwww.epfl.ch/~vetterli/
http://www.ee.columbia.edu/~anastas/
1) Ortega, A.; Ramchandran, K.,
""Rate-distortion methods for image and video compression,"" Signal Processing Magazine, IEEE , vol.15, no.6, pp.23-50, Nov 1998
2) Crouse, M.; Ramchandran, K.,
""Joint thresholding and quantizer selection for transform image coding: entropy-constrained analysis and applications to baseline JPEG ,"" IEEE Transactions on Image Processing, vol.6, no.2, pp.285-297, Feb 1997
3) Ramchandran, K.; Vetterli, M.,
""Rate-distortion optimal fast thresholding with complete JPEG/MPEG decoder compatibility,"" IEEE Transactions on Image Processing, vol.3, no.5, pp.700-704, Sep 1994
4) Ramchandran, K.; Ortega, A.; Vetterli, M.,
""Bit allocation for dependent quantization with applications to multiresolution and MPEG video coders,"" IEEE Transactions on Image Processing, vol.3, no.5, pp.533-545, Sep 1994
Licensing Status: Available for Licensing and Sponsored Research Support
