Tone reproduction: a perspective from luminance-driven perceptual grouping

We address the tone reproduction problem by integrating local adaptation with global-contrast consistency. Many previous works have tried to compress high-dynamic-range (HDR) luminances into a displayable range in imitation of the local adaptation mechanism of human eyes. Nevertheless, while the realization of local adaptation is not theoretically defined, exaggerating such effects often causes unnatural global contrasts. We propose a luminance-driven perceptual grouping process to derive a sparse representation of HDR luminances, and use the grouped regions to approximate local properties of luminances. The advantage of incorporating a sparse representation is twofold: We can simulate local adaptation based on region information, and subsequently apply piecewise tone mappings to monotonize the relative brightness over only a few perceptually significant regions. Our experimental results show that the proposed framework gives a good balance in preserving local details and maintaining global contrasts of HDR scenes.