The perception of color is also an important part of the perceptual process. Hue is determined by the spectral wavelength of the light entering the eye. An average person can distinguish 150 different hues. Intensity is the brightness of the color, and saturation is the amount of whiteness in the color. The eye perceives color because the cones are sensitive to lights of different wavelengths.
Color vision is best in the fovea, and worst at the periphery where rods predominate.
Visual processing compensates for the movement of the image on the retina which occurs as we move around and as the object which we see moves. Although the retinal image is moving, the image that we perceive is stable. Similarly, color and brightness of objects is perceived as constant, in spite of changes in luminance. This can also create optical illusions. Reading There are several stages in the reading process.