Thus, the cone responses c ′ : |last1= has generic name ( help) The von Kries coefficient rule rests on the assumption that color constancy is achieved by individually adapting the gains of the three cone responses, the gains depending on the sensory context, that is, the color history and surround. Ives, and the method is sometimes referred to as the Ives transform or the von Kries–Ives adaptation. The application of Johannes von Kries's idea of adaptive gains on the three cone cell types was first explicitly applied to the problem of color constancy by Herbert E. The method is to apply a gain to each of the human cone cell spectral sensitivity responses so as to keep the adapted appearance of the reference white constant. The von Kries chromatic adaptation method is a technique that is sometimes used in camera image processing. This is known as the Purkinje effect, and arises because the peak sensitivity of the human eye shifts toward the blue end of the spectrum at lower light levels. For example, the bright yellow petals of flowers will appear dark compared to the green leaves in dim light while the opposite is true during the day. Though the human visual system generally does maintain constant perceived color under different lighting, there are situations where the relative brightness of two different stimuli will appear reversed at different illuminance levels. This feature of the visual system is called chromatic adaptation, or color constancy when the correction occurs in a camera it is referred to as white balance. On the other hand, a camera with no adjustment for light may register the apple as having varying color. In all of these situations, human vision perceives that the object has the same color: a red apple always appears red, whether viewed during the day or at night (if the red apple is illuminated as rods in our eyes do not see red). For example, it may be illuminated by sunlight, the light of a fire, or a harsh electric light. A chromatic adaptation transform ( CAT) function emulates this important aspect of color perception in color appearance models.Īn object may be viewed under various conditions. It is responsible for the stable appearance of object colors despite the wide variation of light which might be reflected from an object and observed by our eyes. Chromatic adaptation is the human visual system’s ability to adjust to changes in illumination in order to preserve the appearance of object colors.
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