Petalica Paint

Petalica Paint is a web app that adds color to black-and-white line drawings with a neural network. Illustrators and manga fans upload a sketch, pick a coloring style and get a colored version in seconds, which they can steer with color hints.

It grew out of PaintsChainer, the automatic colorization project from Preferred Networks. You can place small color hints on parts of the drawing, such as hair or clothing, and the model spreads those colors through the related areas while filling the rest itself.

Several style models give different looks, from soft watercolor-like shading to flatter anime coloring. The result can be downloaded and refined further in a regular painting program, so many artists use it as a quick base layer rather than a finished piece.