Direct observation and recorded color images of the same scenes are often strikingly different because human visual perception computes the conscious representation with vivid color and detail in shadows, and with resistance to spectral shifts in the scene illuminant. A computation for color images that approaches fidelity to scene observation must combine dynamic range compression, color consi...

26.1. Physics of the Eye • Explain the image formation by the eye. • Explain why peripheral images lack detail and color. • Define refractive indices. • Analyze the accommodation of the eye for distant and near vision. 26.2. Vision Correction • Identify and discuss common vision defects. • Explain nearsightedness and farsightedness corrections. • Explain laser vision correction. 26.3. Color and...

The eye’s optics form an inverted image of the world on the dense layer of light-sensitive photoreceptors that carpet its rear surface. There, the photoreceptors transduce arriving photons into the temporal and spatial patterns of electrical signals that eventually lead to perception. Four types of photoreceptors initiate vision: The rods, more effective at low light levels, provide our nightti...

New World monkeys exhibit a color vision polymorphism. It results from allelic variation of the single-locus middle-to-long wavelength opsin gene on the X chromosome. Females that are heterozygous for the gene possess trichromatic vision. All other individuals possess dichromatic vision. The prevailing hypothesis for the maintenance of the color vision polymorphism is through a consistent fitne...

Panel tests of color vision (eg FM100-Hue test) lack a common quantitative method for the scoring of cap arrangements. We describe a scoring method applicable to all panel tests that makes use of a novel technique to analyze test cap data, namely the calculation of a moment of inertia from the Color Difference Vectors (CDVs) of any arrangement pattern. Using the Farnsworth D-15 panel, as an exa...

Computational models of colour vision assume that the biological function of colour vision is to detect surface reflectance. Some philosophers invoke these models as a basis for 'externalism' about perceptual content (content is distal) and 'objectivism' about colour (colour is surface reflectance). In an earlier article (Thompson et al. 1992), I criticized the 'computational objectivist' posit...

Our question is, how do things look to the color-blind? But what does that mean? Who are the “color-blind”? Approximately 7 percent of males and fewer than 1 percent of females (of European descent) have some form of inherited defect of color vision and as a result are unable to discriminate some colored stimuli that most of us can tell apart. (Color defective is an alternative term that is oft...

PURPOSE The genetics underlying inherited color vision deficiencies is well understood: causative mutations change the copy number or sequence of the long (L), middle (M), or short (S) wavelength sensitive cone opsin genes. This study evaluated the potential of opsin gene analyses for use in clinical diagnosis of color vision defects. METHODS We tested 1872 human subjects using direct sequenc...

It is well established that about 2 percent of otherwise normal human males are confusers of red and green from birth. There is considerable interest in the question: What do red-green confusers see? From a knowledge of the normal color perceptions corresponding to deuteranopic and protanopic red and green, we may not only understand better why color-blindness tests sometimes fail, and so be in...