Spatial–Illumination Alignment for Controllable Image Illumination Editing

Controllable image illumination editing modifies both the luminance intensity and distribution. Pixel-wise alignment measures reconstruction errors but does not explicitly organize illumination variation with regional brightness. Spatial–illumination alignment couples regional luminance levels with spatial arrangement to guide illumination redistribution. For spatial-illumination consistency, we introduce Illumination Intensity Ranking (IIR) loss, constructing luminance rankings over image patches. Combining luminance consistency and positional consistency, IIR supervises how bright each region should be and where regions of corresponding brightness should occur. We further integrate spatial-illumination alignment with latent bridge matching and enhance informative illumination injection by condition-confirmed initialization. Extensive experiments show that the proposed Illumination-Conditioned Latent Bridge Matching (IC-LBM) achieves state-of-the-art performance on indoor scene relighting, improving the controllability of image illumination editing. Ablations confirm that luminance and positional consistency contribute complementary improvements to illumination reconstruction. IIR provides a structured objective for predicting target illumination without intrinsic decomposition or 3D scene reconstruction. Spatial–illumination alignment introduces explicit illumination supervision for image illumination editing, providing a pioneering perspective on modeling illumination transformations.