VARIANCE-BASED DOMAIN BLOCKS FOR NON-ITERATIVE FRACTAL IMAGE COMPRESSION

摘要

In this paper we propose a variance-based method for selecting the domain blocks in a non-iterative fractal coding scheme of images. In our design, the domain pool is constructed from the mean image in the encoder and is transmitted on-line to the decoder since the mean information is included in the fractal code. We select the domain blocks based on the order of the sorted block variance. To avoid a long delay in sorting a large number of domain blocks, we propose a method to discard the less important blocks and reduce possible redundancy among the domain blocks. We next utilize a modified contractive affine transformation to encode each range block. In a computer simulation, we successfully speed up the sorting process of the domain blocks based on the variance-based method. On the other hand, coding performance significantly improves from conventional fractal coding schemes.