Reference-Based Anime Line Art Colorization by Region Correspondence Using Region Features

The coloring process in anime (Japanese animation) production is a critical yet labor- and time-intensive phase in creating animated content. Reducing time and effort required for this step could significantly lower the time, cost, and effort required for anime production. Various body parts of anime characters are assigned corresponding colors in advance, and these colors often differ from character to character. Therefore, the characters in the line art need to be colored with these predetermined colors. However, as line art lacks information about the appropriate coloring, it becomes difficult to automatically color based solely on the line drawing. This study introduces a colorization system for anime line art based on region estimation using a reference colored image to address this issue. Through interviews with a Japanese animation studio, we identified that anime images are typically segmented into numerous distinct regions. The proposed system inputs a line art and reference colored image of the same cut as the line art and outputs the colored line art based on the features of corresponding regions in the two images. Experimental results using a dataset of real anime works confirm the effectiveness of our system.