薄明視における視覚特性を考慮したトーンリプロダクション手法

抄録

Most tone reproduction operators focus on luminance compression, ignoring chromatic assets. The humanvisual system, however, alters color perception according to the overall level of luminosity. This paper proposes an extensionfor existing operators to simulate chromatic changes under mesopic vision. In such conditions, red responses tend to fadefaster than the remaining stimuli, producing a blue-shift phenomenon known as the Purkinje E ect. Starting with a highdynamic range image, the proposed method proceeds by separating luminance and chrominance components. Luminancecompression is performed by means of any already existing operator, though in this paper, for convenience, the photographicoperator was employed. Chromatic changes are handled in a decoupled fashion according to overall average luminance and byfollowing the observations of previous psychophysical experiments. Finally, compressed luminance and adjusted chrominanceare combined together, providing a displayable, low-dynamic range image. The technique has a low fingerprint thus beingsuitable for interactive rendering.