Dual-Output Multi-Exposure HDR Reconstruction via SDR Fusion and Gain Map Inverse Tone Mapping

We propose DOME-HDR, a dual-output multi-exposure HDRreconstruction framework that jointly produces a perceptually balancedSDR image and a consistent HDR image via gain map inverse tone map-ping. Given three bracketed LDR inputs, DOME-HDR first synthesizesa base SDR using a LoRA-adapted latent diffusion model. A dual cross-attention fusion module injects complementary structural and color cuesfrom the under- and over-exposed images while anchoring on the mid ex-posure for stability. The synthesized SDR then guides HPGM, our HDRPrior-guided Gain Map network, to predict a spatially varying gain mapfor reliable dynamic-range expansion. We evaluate on Kalantari, Tel, andChallenge123 using both full-reference and no-reference metrics, whereDOME-HDR achieves state-of-the-art HDR reconstruction quality; abla-tions further confirm the effectiveness of dual cross-attention and SDR-guided gain map estimation.