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Abstract

A number of successful tone mapping operators for contrast compression have
been proposed due to the need to visualize high dynamic range (HDR) images on
low dynamic range (LDR) devices. They were inspired by fields as diverse as
image processing, photographic practice, and modeling of the human visual
systems (HVS). The variety of approaches calls for a systematic perceptual
evaluation of their performance.

We conduct a psychophysical experiment based on a direct comparison between the
appearance of real-world scenes and HDR images of these scenes displayed on an
LDR monitor. In our experiment, HDR images are tone mapped by seven existing
tone mapping operators. The primary interest of this psychophysical experiment
is to assess the differences in how tone mapped images are perceived by human
observers and to find out which attributes of image appearance account for
these differences when tone mapped images are compared directly with their
corresponding real-world scenes rather than with each other. The human
subjects rate image naturalness, overall contrast, overall brightness, and
detail reproduction in dark and bright image regions with respect to the
corresponding real-world scene.

The results indicate substantial differences in perception of images produced
by individual tone mapping operators. We observe a clear distinction between
global and local operators in favor of the latter, and we classify the tone
mapping operators according to naturalness and appearance attributes.