Large textures that can provide realistic details are widely used in modeling, gaming, art design, etc. Texture synthesis is a way to create large textures based on a small sample pattern, which can be obtained by image examples or hand­drawn work by an artist. Different methods that aim to achieve better visual effects on reducing or avoiding seams and distortions during synthesis are proposed. It has been a popular topic both in computer graphics and computer vision for many years. However, most of the synthesis methods are automatic and take images as the input. There are few methods designed for artists who want to control and create patterns manually. The goal of our Diffusion Mosaics is to introduce a graphics tool that allows the artist to create tiles that can be seam­ lessly concatenated. In this way, non­periodic textures of arbitrary size can be produced at very low memory costs. We rely on a special kind of tiles called Wang tiles, which are squares with colored edges. Neighboring tiles should share the same edge color at the common border. The texture tiles are designed in such a way that if this constraint is fulfilled, the transition from one tile to the next will be seamless. It becomes possible to create a large non­periodic final texture. In our system, each tile can be filled with hand­drawn patterns using diffusion curves, which is a vector graphics primitive created by diffusing the given colors of defined Bezier curves, which has been proven to be a useful alternative to purely pixel­based design that artists typically rely on. They also match our application well, as, by adding border­color constraints to the tile, solving the diffusion process results in tiles that match the neighboring tiles naturally, hence avoiding any seams. The tool gives creative freedom to the artist that they can even draw the pattern outside the tile area, resulting in an automatic update of all other tiles when needed to ensure consistency. Finally, for more complex illustrations and back­ wards compatibility to software such as Photoshop, pixel­based images are also supported and can be integrated.