Showing papers by "Hannes Hartenstein published in 2000"

Region-based fractal image compression

Abstract: A fractal coder partitions an image into blocks that are coded via self-references to other parts of the image itself. We present a fractal coder that derives highly image-adaptive partitions and corresponding fractal codes in a time-efficient manner using a region-merging approach. The proposed merging strategy leads to improved rate-distortion performance compared to previously reported pure fractal coders, and it is faster than other state-of-the-art fractal coding methods.

Lossless acceleration of fractal image encoding via the fast Fourier transform

Abstract: In fractal image compression the encoding step is computationally expensive. We present a new technique for reducing the encoding complexity. It is lossless, i.e., it does not sacrifice any image reconstruction quality for the sake of speedup. It is based on a codebook coherence characteristic of fractal image compression and leads to a novel application of the fast Fourier transform-based cross correlation. The proposed method is particularly well suited for use with highly irregular image partitions for which most traditional (lossy) acceleration schemes lose a large part of their efficiency. For large ranges our approach outperforms other currently known lossless acceleration methods.