Fast Fractal Encoding through FFT using Modified Crosscorrelation based Similarity Measure

S.B Dhok, R.B. Deshmukh, A.G. Keskar
2010 Proceedings of the Annual International Conference on Advances in Distributed and Parallel Computing ADPC 2010 ADPC 2010   unpublished
The image compression using fractal transform is a promising method which is potentially capable of achieving very high compression ratios. The major drawback of fractal inage compression is large encoding time, though the decoding time is negligible. In this paper, a new similarity measure based on normalized cross-correlation of mean subtracted range and domain blocks is proposed.The fast fractal encoding algorithm based on the proposed similarity measure is well suited for FFT based
more » ... domain operations to speed up the encoding process. The implemented algorithm employs exhaustive search of similar domain blocks for each range block unlike other limited domain search methods. The algorithm works largely in frequency domain and operates on entire domain image instead of overlapping domain blocks.The contrast and brightness parameters of fractal transformation are easily calculated during the course of computation of similarity index matrix. Though the proposed method shows little dB drop in Peak signal to noise ratio(PSNR) values, the encoding time is reduced considerably with average speedup factor of 30 as compared to the full search method. Index Terms -cross-correlation based similarity measure, fast fractal encoding, fractal image compression, fractal transform.
doi:10.5176/978-981-08-7656-2atai2010-60 fatcat:bqcnek5afzf6jgv6gi4y24lghe