Towards Seamless Lunar Mosaics: Deep Radiometric Normalization for Cross-Sensor Orbital Imagery Using Chandrayaan-2 TMC Data
This study addresses the challenge of radiometric inconsistency in multi-mission lunar orbital imagery caused by variations in illumination, sensors, and imaging conditions, which hinders seamless mosaicking. The work proposes the first cross-mission radiometric normalization framework based on conditional generative adversarial networks (cGANs), mapping Chandrayaan-2 Terrain Mapping Camera (TMC) data—augmented with SELENE imagery—as inputs to the Lunar Reconnaissance Orbiter Camera Wide Angle Camera (LROC WAC) reference standard. The approach employs a U-Net generator and a PatchGAN discriminator, combined with a patch-based training scheme and an overlap-aware inference strategy to preserve large-scale structural continuity while effectively eliminating visible seams. Experimental results demonstrate that the method significantly outperforms conventional histogram matching in terms of SSIM, PSNR, and RMSE metrics, substantially improving tonal uniformity and structural consistency across multi-source lunar images.