Blasi, G. DiGallo, G.Petralia, M.P.S. Battiato and G. Gallo and F. Stanco2014-01-272014-01-2720063-905673-58-4https://doi.org/10.2312/LocalChapterEvents/ItalianChapConf2006/267-271Photomosaic is a technique which transforms an input image into a rectangular grid of thumbnail images preserving the overall appearance. The typical photomosaic algorithm searches from a large database of images one picture that approximates a block of pixels in the main image. Since the quality of the output depends on the size of the database, it turns out that the bottleneck in each photomosaic algorithm is the searching process. In this paper we present a technique to speed-up this critical phase using the Antipole Tree Data Structure. This improvement allows the use of larger databases without requiring much longer processing time, leading to very interesting results. Further we present some ideas to render an image in a "photomosaic style". These techniques are based on QuadTree and fractal images and allow the creation of very interesting "photomosaic effects".Categories and Subject Descriptors (according to ACM CCS): J.5 [Arts and humanities]: Architecture, Fine Arts