Hweover, our perception of an object's size remains the same even if its visual angle changes. This is the the law of size constancy . Perceiving brightness forms another aspect of visual perception. Brightness is a subjective reaction to levels of light and is affected by the amount of light emitted by an object. This is known as luminance .
Visual acuity increases with increased luminance.
This is probably one of the reasons for using high luminance. 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.