Lossless acceleration of fractal image encoding via the fast Fourier transform

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.