Reference-based manga colorization by graph correspondence using quadratic programming

Manga (Japanese comics) are popular all over the world. However, most existing manga are monochrome. If such monochrome manga can be colorized, readers can enjoy the richer representations. In this paper, we propose a semiautomatic colorization method for manga. Given a previously colored reference manga image and target monochrome manga images, we propagate the colors of the reference manga to the target manga by representing images as graphs and matching graphs. The proposed method enables coloring of manga images without time-consuming manual colorization. We show results in which the colors of characters were correctly transferred to target characters, even those with complex structures.