Abstract: Art often provides valuable hints for technological innovations especially in the field of Image Processing and Computer Graphics. In this paper we survey in an unified framework three methods to transform a raster input image into good quality mosaics: artificial mosaic, photomosaic and puz zle image mosaic. The common and different ideas among these methods are reported. The main goal of all the methods is to produce good results in an acceptable time and without user intervention. Examples reported in the paper show how the right mixture of mathematical tools may lead to impressive results.