A Unified Framework for Industrial Cel-Animation Colorization with Temporal-Structural Awareness

Line drawing colorization is a critical step in the celanimation industry, where artists use a paint bucket tool to apply RGB values to segments based on a character's color design sheet. Current automated methods predominantly focus on consecutive frame colorization, using a single adjacent frame as a reference. These approaches often face two major challenges: inaccurate segment colorization due to significant deformations between the target and reference frames, and incomplete information in a single frame that prevents finding suitable reference segments, leading to poor color accuracy. To address these challenges, we propose a novel colorization framework that integrates both temporal and structural information. Using multiple reference keyframes, our method effectively captures temporal information across frames, enhancing the accuracy of colorization for transitional frames. In addition, we leverage structural information through a matching-based approach that ensures precise segment alignment across frames. This combination of temporal awareness through multi-frame references and structural alignment improves colorization robustness, even in scenarios with large motion and deformations. Our method outperforms existing techniques, demonstrating superior colorization accuracy and consistency in industrial cel-animation workflows.