The symbols on the playing card are now black and the body of the card is reflecting green light. The fourth photograph illustrates the objects under blue illumination. The playing card is reflecting blue light with black symbols and the pepper is reflecting blue light only on the highlights. We invite our visitors to further explore this concept using our interactive Java tutorial on color filters . The human eye is sensitive to very slight differences in color and is probably capable of distinguishing between 8-12 million individual shades of color.
Most colors contain some proportion of all wavelengths in the visible spectrum.
What really varies from color to color is the distribution of wavelengths in a given color. The predominant wavelengths determine the basic hue of the color which can be, for example, purple or orange. The ratio of the dominant wavelengths to other wavelengths determines the color saturation of the sample and whether it appears pale or deeply saturated. This is nicely illustrated below in the Munsell Color Tree , where each color is represented by a distinct position on the tree. Hue color value is represented by placement on the circumference, saturation by the horizontal distance of the color from the central axis, and brightness by the vertical position on the trunk.