Paint Bucket Colorization Using Anime Character Color Design Sheets

TL;DR

This paper presents a novel inclusion matching approach for automated line art colorization in animation, improving accuracy and consistency in keyframe and frame-to-frame colorization tasks by understanding segment relationships.

Contribution

The work introduces inclusion matching combined with segment parsing and color warping, along with a new dataset, to enhance automated colorization accuracy in animation production.

Findings

Outperforms existing methods in keyframe and frame colorization tasks.

Achieves more accurate and consistent coloring across animation frames.

Demonstrates effectiveness on custom benchmarks and hand-drawn animations.

Abstract

Line art colorization plays a crucial role in hand-drawn animation production, where digital artists manually colorize segments using a paint bucket tool, guided by RGB values from character color design sheets. This process, often called paint bucket colorization, involves two main tasks: keyframe colorization, where colors are applied according to the character's color design sheet, and consecutive frame colorization, where these colors are replicated across adjacent frames. Current automated colorization methods primarily focus on reference-based and segment-matching approaches. However, reference-based methods often fail to accurately assign specific colors to each region, while matching-based methods are limited to consecutive frame colorization and struggle with issues like significant deformation and occlusion. In this work, we introduce inclusion matching, which allows the network to understand the inclusion relationships between segments, rather than relying solely on direct visual correspondences. By integrating this approach with segment parsing and color warping modules, our inclusion matching pipeline significantly improves performance in both keyframe colorization and consecutive frame colorization. To support our network's training, we have developed a unique dataset named PaintBucket-Character, which includes rendered line arts alongside their colorized versions and shading annotations for various 3D characters. To replicate industry animation data formats, we also created color design sheets for each character, with semantic information for each color and standard pose reference images. Experiments highlight the superiority of our method, demonstrating accurate and consistent colorization across both our proposed benchmarks and hand-drawn animations.