A novel technique for opus vermiculatum mosaic rendering

In this paper we present a method to generate a digital mosaic starting from a raster input image. Mosaics generation of artistic quality is challenging. The basic elements, the tiles, typically small polygons, must be packed tightly, emphasizing orientations chosen by the artist. An adhoc boundaries detection have to be performed according to the directional guidelines. Different mosaic styles can be automatically rendered, depending on artistic techniques considered ("opus musivum", "opus vermiculatum", etc.). The proposed method is able to reproduce the colors of the original image emphasizing relevant boundaries by placing tiles along their direction. The boundaries detection is based on the statistical region merging algorithm. In particular the technique is able to reproduce the "opus vermiculatum" mosaic style. Several examples reported in the paper show how the right mixture of mathematical tools together with century proved ideas from mosaicists may lead to impressive results.