Image analysis – Image compression or coding – Pyramid – hierarchy – or tree structure
Patent
1996-04-11
1999-12-21
Au, Amelia
Image analysis
Image compression or coding
Pyramid, hierarchy, or tree structure
382166, 382248, 382253, 382281, G06K 936, G06K 946
Patent
active
060059818
ABSTRACT:
An encoding process is configurable to trade calculational complexity for bit rate while maintaining code format and image quality. A software encoder which implements the encoding process monitors bandwidth and processor utilization and when either is overtaxed, adjusts complexity to compensate. If further adjustment is required, encoded image quality is changed. Changing the search process or search window size used during searches for predictive blocks or changing a threshold which is compared to inter-code length before determining whether to calculate an intra-code changes complexity. An intra-coding method subtracts a base which depends on codes representing neighboring blocks from coefficients for a current block to determine a difference which is often small and easily compressed. Additionally, restricting a quadtree structure for one color component to a sub-tree of a quadtree structure for another other color component improves compression efficiency and reduces coding complexity.
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Po et al., Quadtree based colour quantisation image compression, Nov. 9, 1995, 1988-1990, Electronics Letters.
Jin et al., Color Image Sequence Coding With Variable Block Size Motion, 1993, 974-977, IEEE Tencon '93.
Ng Hak-Leong
Ran Xiaonong
Au Amelia
Johnson Timothy M.
Millers David T.
National Semiconductor Corporation
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