Domain search using shrunken images for fractal image compression

摘要

In this paper, we propose a new way of limiting the number of candidates of domains by using the shrunken image for Voronoi-based fractal image compression. And we show the result of computer simulations and confirm the effects of the proposed method. The process of domain search is the most critical process of fractal image compression because it takes exorbitant time to perform it. In the process of domain search, we have to use the term of Sigma r(i), Sigma d(i), Sigma r(i)(2), Sigma d(i)(2) and Sigma r(i)d(i), where r(i) is the sum of pixels for the ith range and d(i) is same one for the corresponding domain. We can calculate these terms by using cumulations for the rectangular range, but for the Voronoi range, since the shape of a range is different from each other, we can not use the cumulations for calculating these terms. Therefore, it is necessary to limit the number of candidates of domains for finding the appropriate domain in order to reduce the time of compressing image.