Optimum Tone Reproduction for Oil Paintings

Abstract

Tone reproduction, an input/output property of light-dark information is one of the most important image qualities of an image system. Optimum tone reproduction curves have been proposed for imaging systems. But in paintings the tone reproduction itself has not been discussed because of difficulty of its quantification. In the preceding paper, we investigated optimum tone reproduction for line-drawings by making them from photographs by non-photorealistic rendering, controlling their tone reproduction systematically, and asking the testee to evaluate their tone reproduction subjectively. In the present paper, optimum tone reproduction for oil paintings was investigated by producing oil paintings, which are acceptable as oil paintings for everyone, using a similar method to that employed in preceding paper. As a result, it was found that a darker image was preferred for low-key image and a lighter image was preferred for high-key image for oil paintings, compared with photographs and line-drawings. Chroma of images acceptable as oil paintings for everyone is higher than that of photographs of optimum tone reproduction, but its level depends on kinds of image such as landscape and portrait. Chroma as high as 20 is required for landscape images and that as low as 10 is required for portraits.