Ant colony algorithm for fractal image compression based on edge property

The encoding step in fractal image compression is expensive because large numbers of sequential search through a list of Domains (portions of the image) are carried out while attempting to find the best match for a Range block (another portions of the image). In order to solve the encoding problem ant colony optimization was carried out. Instead of the sequential search, a direction map is built according to the edge-type of image blocks, which directs the ants in the colony to regions consisting of candidate Domains of higher similarity. Experimental results show that this method can work well and can speedup the encoding process.