Psychovisual Assessment of Tone-Mapping Operators for Global Appearance and Colour Reproduction

Céline Villa, Raphaël Labayrade
Université de Lyon, France
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To identify people’s preference, psychovisual tests are carried out in virtual environment. Images of scenes used for psychovisual tests are natively High Dynamic Range (HDR) images. However, in order to allow a Low Dynamic Range (LDR) display device to project HDR pictures, their dynamic range must be compressed with a tone-mapping operator (TMO). Thus, before tests are carried out, selection of the most suitable TMO, perceptually speaking, is required to present images faithfully, depending on the aim of the application.

In this paper, three different experimental protocols are proposed for assessing the applications of a display device used for psychovisual tests and selecting the most suitable TMO from six candidates. An additional goal is to give a first idea of the applications that can be addressed by this device. Two subjective experiments were conducted and are presented in the paper. The first one is divided in two steps. The results of three different protocols (two protocols in the first test and the third in the second test) for the identification of the preferred TMO for five different scenes are compared and LDR image defects noticed by observers are highlighted in the paper.