Beyond Fixed Luminance: Towards Panchromatic and Orthochromatic Image Colorization
Most image colorization systems operate in $Lab$ space by predicting chroma ($ab$) while preserving an input-derived luminance channel ($L$). While effective on standard benchmarks, this fixed-luminance design restricts brightness changes and becomes unreliable when grayscale formation deviates from natural-image luminance, as in historical orthochromatic photography. We propose a luminance-agnostic colorization framework that formulates colorization as full-RGB image editing using a foundation image-editing model. To bridge modern panchromatic and historical orthochromatic conditions, we introduce a mixed grayscale objective that trains the model under both standard luminance grayscale a...
| Authors | Swarnim Maheshwari, Syed Imam Ali, Vineeth N. Balasubramanian |
|---|---|
| Primary category | cs.CV |
| Published | 11 August 2026 |
| Last updated at source | 12 August 2026 |
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