Objective assessment of tone mapping algorithms

There has been a growing interest in recent years to develop tone mapping algorithms that can convert high dynamic range (HDR) to low dynamic range (LDR) images, so that they can be visualized on standard displays. With a number of tone mapping algorithms proposed, a natural question is which one gives the best performance. Although subjective assessment methods provide useful references, they are expensive and time-consuming, and are difficult to be embedded into the design stage of tone mapping algorithms for optimization and parameter tuning purposes. This paper focuses on objective assessment of tone mapping operators. Inspired by the success of the structural similarity index method for image quality assessment, we propose a new objective assessment algorithm that creates multi-scale similarity maps between HDR and LDR images. Our experiments show that the proposed method correlates well with subjective rankings of existing tone mapping operators. Furthermore, we demonstrate how the proposed algorithm can be employed in an existing tone mapping algorithm for optimal parameter tuning.