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Efficiency of shape-adaptive 2-D transforms for coding of arbitrarily shaped image segments

: Sikora, T.; Bauer, S.; Makai, B.


IEEE transactions on circuits and systems for video technology 5 (1995), Nr.3, S.254-258
ISSN: 1051-8215
ISSN: 1558-2205
Fraunhofer HHI ()
adaptive signal processing; discrete cosine transforms; image coding; image segmentation; transform coding; transforms; karhunen-loeve transform; arbitrarily shaped image segments; shape-adaptive 2-d transforms; klt; shape-adaptive dct method; intraframe coding; statistical transform gain; shape-adaptive dct algorithm; lower complexity; efficiency

We introduce a formula to compute an optimum 2-D shape-adaptive Karhunen-Loeve transform (KLT) suitable for coding pels in arbitrarily-shaped image segments. The efficiency of the KLT on a 2-D AR(1) process is used to benchmark two other shape-adaptive transforms described in literature. It is shown that the optimum KLT significantly outperforms the well known shape-adaptive DCT method introduced by Gilge et al. (1989) for coding Segments of arbitrary shape in intraframe coding mode. A statistical transform gain close to the Gilge-method can be achieved with a shape-adaptive DCT algorithm introduced by Sikora and Makai (see Proc. Workshop Image Anal. Image Coding, Berlin, FRG, Nov. 1993) which is implemented with much lower complexity.