HDR image compression with optimized JPEG coding
Azza Ouled Zaid, Amira Houimli · 2017
This paper presents an efficient compression system adapted to High Dynamic Range (HDR) images. First a Tone Mapping Operator (TMO) generates the Low Dynamic Range (LDR) version of the HDR content together with its extra information. The obtained LDR image is encoded using an optimized JPEG coding scheme, whereas the extra information is encoded as side data. Specifically, the optimized JPEG based algorithm constructs near-optimal rate-distortion quantization tables using DCT coefficient distribution statistics and Lagrangian optimization approach. To ensure accurate HDR reconstruction, the extra information is compressed with conventional JPEG encoder using the highest quality level. The aim of the proposed HDR coding system is twofold. First, it performs a bit allocation mechanism, to achieve near-optimal rate control. Second, it maintains the backward compatibility with the conventional JPEG. Experiments show that the compression performance of the proposed HDR coder outperforms that of the reference method.