Fast Multi-Stage Motion-Compensated Approach for HDR

Multi-frame High Dynamic Range (HDR) imaging is a technique to improve details while capturing scenes with large variations in luminosity by blending together a stack of images captured using varying exposure values. Local motion between the stack of images often result in ghost artifacts or reduced dynamic range especially in over-exposed or underexposed regions. This paper proposes a method to mitigate these problems using a novel multi-stage algorithm. At each stage of the proposed method, intermediate HDR images are generated from consecutive exposure pairs using a computational unit termed as Basis HDR. The outputs produced by each Basis HDR unit is ensured to be free of ghosts using a novel algorithm to estimate local motion in the scene. Qualitative and quantitative comparison studies show that the proposed method generates images with improved dynamic range, minimal ghosts and a higher MEF-SSIM score as compared to existing state-of-the-art. The proposed method can process a 3-frame HDR on a smartphone in under a second thus making it a fast and reliable algorithm for smartphones.