Analysis of tristimulus interdifference and contextual color correction

摘要

We explore how an RGB representation can be computed from a spectral description of real images, with many different colors. To pass from spectral distribution to tristimulus values, several color-matching functions (CMFs) were proposed, derived from experimental setups with simplified visual conditions, considering the colors pointwise and independently from any visual context. A high interdifference is observed in cone spatial distribution between human subjects, without any corresponding significant difference in final color sensation. It is likely that a spatial compensation is performed by human observers that strongly decreases the subjectivity in color perception, and we ask if a similar principle should be considered in digital imaging. We investigate the interdifference among some CMFs when used to compute color information in complex visual conditions, where multiple, spatially distributed different colors are present. This is relevant in synthetic image generation of scenes under different illuminants, computed at the spectral energy distribution at 5-nm intervals, to be converted into RGB for monitor display. The analysis of the interdifference among tristimulus colors obtained using different CMFs shows a significant decrease of the interdifference when a contextual color correction is applied, based on Von Kries or Retinex methods.