Figure 2
From: Geometry of color perception. Part 1: structures and metrics of a homogeneous color space
An example of effect of background change. The inner disks appearing in the center of the two images are exactly the same physical color stimuli. However, the one in the left image is perceived, with respect to its background illumination, as a very saturated green, instead, after the change of background illumination shown by the image on the right, the color stimulus is perceived as yellowish. Due to the small size of the color stimuli on this document, they are surrounded by a thin black circle to enhance their visibility