Abstract
Construct a High Dynamic Range (HDR) image is the primary method to solve the information loss caused by insufficient dynamic range of cameras. We propose a technique for fusing a bracketed low dynamic range (LDR) image sequence of varying exposures into an HDR image, skipping the physically-based HDR assembly step. Traditionally approaches often rely on complicated algorithms to select good regions from the input LDR images for the fusion. However, we found that the selection strategy can purely base on JPEG compression bits, bypassing the calculations of image low-level features, such as image gradients, local saturations, over/under exposure evaluations, as long as the input LDR image is compressed by the JPEG formats. In this way, lots of computations can be saved. In particular,we extract the coding bits from the intermediate product of the JPEG. The coding bits of blocks can be modified as the weights for the exposure fusion. Well-exposed regions often require higher bits for the compression while overexposure or saturated regions often correspond to lower bits. The objective and subjective evaluations demonstrate the effectiveness of our method.