Mapping-free high dynamic range image compression

High Dynamic Range (HDR) image compression is mostly concerned on lossless coding strategies. Conventional HDR compression schemes usually require mapping of HDR into the low dynamic range (LDR) images, so that conventional image coders, such as JPEG and JPEG2000 can be applied. This paper proposes a low complex approach to compress RGBE and OpenEXR HDR content without using any mapping step or modification of the existing JPEG and JPEG2000 codecs. The experimental results indicate that the proposed method can be used in further compressing the lossless RGBE and OpenEXR HDR formats. The overall rate-distortion performance of the proposed method is comparable to the two state of the art approaches, yet with low complexity due to the exclusion of integer to floating-points conversion and tone-mapping.