A neural field model for color perception unifying assimilation and contrast
Fig 3
A typical color matching experiment.
Upper row, left to right. For each of the three pairs of (gray, yellow) large squares, the central patches have identical colors. Their HSL coordinates are (120°, 55%, 46%), (120°, 85%, 71%), (60°, 57%, 56%), respectively. The HSL color space is extensively used in computer graphics and defined in [21]. Lower row, left to right. One of the authors (A.S.) has modified the HSL coordinates of the left central patch, in order to obtain perceptually equal patches (as much as possible). This is called matching. We can see how far the “perceived” HSL are from reality: (138°, 55%, 39%), (140°, 41%, 59%), (66°, 29%, 54%). The reader probably does not perceive the two patches as perceptually equal, because matching is subject-dependent.