Related Experiment Video
Updated: Aug 6, 2026

04:43
Visualizing Visual Adaptation
Published on: April 24, 2017
Gray Anchoring: A New Computational Theory for Biological Color Constancy
Kai-Fu Yang1,2, Dajun Xing3, Yong-Jie Li4,5
1MOE Key Laboratory for NeuroInformation, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China. yangkf@uestc.edu.cn.
Neuroscience Bulletin
|July 21, 2026
Summary
This study introduces gray anchoring (GA) theory to explain color constancy, a key aspect of human vision. GA theory proposes how early visual processing identifies gray surfaces, aiding color perception and offering computational solutions.
Area of Science:
- Neuroscience
- Computer Vision
- Computational Neuroscience
Background:
- Color constancy is crucial for human color vision.
- Existing anchoring theories offer insights into lightness perception but lack specifics for color constancy.
- The neural basis for color constancy remains debated.
Purpose of the Study:
- To introduce a novel computational framework, gray anchoring (GA) theory, explaining early visual system contributions to color constancy.
- To demonstrate GA's operation in the chromatic domain by identifying gray surfaces in complex scenes.
- To propose a neural implementation of GA in the visual cortex.
Main Methods:
- Developed a novel computational framework: gray anchoring (GA) theory.
- Analyzed the chromatic domain to identify gray surfaces in scenes.
- Quantitatively analyzed computational processing of concentric double-opponent (DO) cells in the primary visual cortex.
Main Results:
- Demonstrated how the GA rule identifies gray surfaces in color-biased scenes.
- Proposed that concentric DO cells in V1 may implement GA for illuminant estimation.
- Showcased GA as an effective solution for computational color constancy.
Conclusions:
- GA theory provides a functional explanation for concentric DO receptive fields.
- GA theory offers an efficient computational solution for color constancy in computer vision.
- This work bridges understanding between human color perception and artificial vision systems.
Related Concept Videos
Color Vision
Color perception begins in the retina, the light-sensitive layer at the back of the eye. Two main theories explain how colors are seen: the trichromatic theory and the opponent-process theory. The trichromatic theory, proposed by Thomas Young in 1802 and extended by Hermann von Helmholtz in 1852, suggests that color vision is based on three types of cone receptors in the retina. These cones are sensitive to different but overlapping ranges of wavelengths corresponding to red, blue, and green.
Channel Rhodopsins
Most organisms use photoreceptors to sense and respond to light. Examples of photoreceptors include bacteriorhodopsins and bacteriophytochromes in some bacteria, phytochromes in plants, and rhodopsins in the photoreceptor cells of the vertebral retina. The light-sensitive property of these receptors is because of the bound chromophores, such as bilin in the phytochromes and retinal in the rhodopsins.
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Rhodopsins belong to the family of cell surface proteins called G-protein coupled receptors,...
Photoreceptors and Visual Pathways
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...
Perceptual Constancy
Perceptual constancy is the ability to recognize that objects remain consistent and unchanged even when their appearance varies due to changes in sensory input. There are four main types of perceptual constancy: size constancy, shape constancy, color constancy, and brightness constancy.
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...
The Retina
The retina is a layer of nervous tissue at the back of the eye that transduces light into neural signals. This process, called phototransduction, is carried out by rod and cone photoreceptor cells in the back of the retina.
Vision
Vision is the result of light being detected and transduced into neural signals by the retina of the eye. This information is then further analyzed and interpreted by the brain. First, light enters the front of the eye and is focused by the cornea and lens onto the retina—a thin sheet of neural tissue lining the back of the eye. Because of refraction through the convex lens of the eye, images are projected onto the retina upside-down and reversed.

