Mosaic animations from video inputs

Abstract

Mosaic is a Non-Photorealistic Rendering (NPR) style for simulating the appearance of decorative tile mosaics. To simulate realistic mosaics, a method must emphasize edges in the input image, while placing the tiles in an arrangement to minimize the visible grout (the substrate used to glue the tiles that appears between them). This paper proposes a method for generating mosaic animations from input videos (extending previous works on still image mosaics) that uses a combination of a segmentation algorithm and an optical flow method to enforce temporal coherence in the mosaic videos, thus avoiding that the tiles move back and forth the canvas, a problem known as swimming. The result of the segmentation algorithm is used to constrain the result of the optical flow, restricting its computation to the areas detected as being part of a single object. This intra-object coherence scheme is applied to two methods of mosaic rendering, and a technique for adding and removing tiles for one of the mosaic rendering methods is also proposed. Some examples of the renderings produced are shown to illustrate our techniques. © Springer-Verlag Berlin Heidelberg 2007.