Perceptual color includes both the actual color and the eye of the one who perceives it, which can alter the real color of an object. That is, since vision depends upon the reception of light that is reflected off of objects, because of the degree of light and shadows, the eye may not send an exact image to the brain and, therefore, a person may perceive color differently from what truly exists.
Therefore, because of the degree of light, perceptual color of an object may differ from time to time. For instance, mountains appear to be purple at times such as sunset. Interest in this perceptual color is evidenced in Claude Monet's series of paintings of a haystack at different times of the day. His work proves that no object is intrinsically a certain color; rather, color is perceived. Of these haystack paintings, one art instructor explains Monet's use of perceptual color:
In each painting, the color of the haystack is different because the light shining on the haystack is different. The color of the haystack is determined by the colors the haystack absorbs. The color we see is simply the colorized light that is not absorbed and that is reflected into our eyes.