An efficient decoding scheme for fractal image compression

Abstract

Fractal image compression is famous for its particular iterated decoder and the magic Collage theorem. This paper proposes an efficient decoding scheme. In fractal image compression, an image is partitioned into nonoverlapped range blocks and overlapped domain blocks. That is, there are more domains than ranges. Hence many pixels {p/sub i/} in the image do not belong to any domain blocks and these pixels need not be computed iteratively. We can compute them only once in the last iteration. Moreover, some other pixels {p/sub i/} can also be computed noniteratively if they only map to {p/sub i/}. Therefore iterative computations on {p/sub i/} and {p/sub i/} are redundant. We can eliminate the redundancy to accelerate the decoder without any loss on fidelity. In our experiment, the polished procedure can speed up on a large scale. It takes only 0.2-0.3 seconds to decode a 512 by 512 image on a Pentium II 450 PC running Windows 98.