Vision psychophysics

Anstis, S. M. and P. Cavanagh (1983). A minimum motion technique forjudging equiluminance. In Colour Vision Psychophysics and Physiology, J. D. Mollon and L. T. Sharpe (eds.). London Academic Press, pp. 66-77. 

West, P. and J. Mellerio (2005). An innovative instrument for the psychophysical measurement of macular pigment optical density using a CRT display. International Color Vision Society Annual Meeting, Lyons, France. 

Both models, the one given by Judd and the model of Richards and Parks, are psychophysical models of color perception. No explanation is given on how or why the results would depend on either the average apparent reflectance or the average luminance. They are phenomenological descriptions of color vision and not computational theories of color vision (Marr 1982). In this respect, the parallel model described in Chapter 10 in combination with local color shifts described in Section 11.2 is much more satisfying. 

In summary, with this book, we have made a step toward a better understanding of a computational theory of color constancy. The main question, which algorithm is used by the human vision system, however, is still unsolved. In the future, noninvasive techniques that help to visualize the workings of the human brain in combination with additional psychophysical experiments may one day lead to the actual algorithm used by the visual system. 

The vision literature contains a great variety of different absorption profiles for the chromophores of vision. They have been acquired using a variety of means. The chemist prefers to measure the absorbance of individual chromophores in a standard one centimeter cell as a function of wavelength. The chromophore is usually present in a dilute solution. The psychophysiologist prefers an in-vivo test under conditions of differential adaptation. The results from these two methods have shown considerable disparity. This work will show that, for the in-vivo situation (and adequate differential adaptation in the psychophysical situation), the actual L-channel peak is in human vision is at 625 nm. This is the peak wavelength observed in all other biological species. 

Virtually all of the experiments in psychophysics of the last 50 years have assumed the long wavelength chromophores of vision peaked in the region of 575 nm. They have relied upon a false assumption The peak spectral absorption of the L-channel in human vision is at 625 nm. 

The 1992 Merbs Nathans paper addresses anomalous color vision based on a dichotomy, the possible complete absence of either the L-channel or M-channel chromophores of vision192. Their definition of a complete deutranope as one completely lacking a green, or M-channel, chromophore does not conform to the original definition of the term or as it is used in this work (Section 18.1). No report has been found in either the electrophysiological or psychophysical literature of any sighted human, color-blind or not, who totally lacked an operational M-channel in his visual system. At photopic levels of illumination, the most chromatically limited deutranope exhibits a luminous threshold function within the normal statistical variation of color normals. 

Fulton AB, Rushton WA. The human rod ERG correlation with psychophysical responses in light and dark adaptation. Vision Res 1978 18(7) 793-800. 

Man is blessed with the sense of smell, taste, touch, vision, and hearing. Three of these senses (touch, vision, hearing) are referred to as the physical senses and are used for detection of mechanical, thermal, photic, and acoustic energy. The other two, the chemical senses, are used for the detection of volatile and soluble substances. The stimuli that excite the physical senses can be measured by both physical and psychophysical means. The volatile and soluble substances that excite the chemical senses can be defined but the stimuli caused by these substances can only be measured by psychophysical means.l z For all practical purposes these stimuli cannot be expressed as some unit of energy, instead they have to be expressed in the dimensions of quality, intensity, duration, and like and dis-1 ike. 

Baumbach J. (2010), Psychophysics of human vision The Key to Improved Camouflage Pattern Design, Land Warfare Conference, Brisbane, 13-18. 

The stochastic resonanoe peradigm is compatible with single-neuron models or synaptic and channels properties and ap>phes to neuronal assembhes activated by sensory inputs and perceptual processes as well. In hterature, the landmark experiments including psychophysics, electrophysiology, functional MRI, human vision, hearing and tactile... 

Psychophysics, along with cognitive science, has studied human vision for a long time (Marr, 1982). Some techniques in machine vision are related to what is known about human vision. Many researchers in computer vision are more interested in preparing computational models of human vision than in designing machine vision systems. Therefore, some of the techniques used in machine vision have a strong similarity to those in psychophysics. 

To evaluate the performance of the proposed Braille display, psychophysical tests have been performed using visually impaired persons. Seven individuals participated in the test, six of them were males and one was a female with an overall average age of 32.6 years. All of them were employees of the Korean Assoeiation of the Visually Impaired. One of them had weak vision and the others were completely blind. The software environment graphical... 

Mollon, J. D., and Sharpe, L. T., eds. (1983). Colour Vision Physiology and Psychophysics, Academic Press, New York. 

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