Optimized tone mapping with LDR image quality constraint for backward-compatible high dynamic range image and video coding

Abstract

Backward compatibility to low dynamic range (LDR) displays is an important requirement for high dynamic range (HDR) image and video coding in order to enable a successful transition to HDR technology. In a recent work [1], an optimized solution for tone mapping and inverse tone mapping of HDR images is achieved in terms of mean square error (MSE) of the logarithm of luminance values of HDR image pixels for backward-compatible compression. Although this pioneer optimization approach provides a well settled mathematical framework for tone mapping, one of its important shortcomings is not to take the quality of the resulting LDR images into account during the formulation. In this paper, we include the LDR image quality as a constraint to optimization problem and develop a methodology to compromise the trade-off between HDR image quality and LDR image quality during HDR image and video coding. The developed methodology is verified on HDR images by showing the increase (decrease) in the quality of generated LDR images while losing (gaining) from the rate-distortion performance of HDR image coding.