Theories of color vision

Thomas Young was the main pioneer to publicly hypothesize that color vision came about due to intrinsic properties of the human retina. Hesternely believed that there are three kinds of nerves which, when stimulated, would produce sensations of red, green, and blue. The brain would then weigh the relative intensities of these sensations and generate a color percept. These ideas were mainly taken on by Herman von Helmholtz, who saw them as a specific application of Müller's Law.

1. Theories of Color Vision Theory BY Dr. SREEREMYA.S FACULTY OF BIOLOGY

2. Thomas Young was the main pioneer to publicly hypothesize that color vision came about due to intrinsic properties of the human retina. Hesternely believed that there are three kinds of nerves which, when stimulated, would produce sensations of red, green, and blue. The brain would then weigh the relative intensities of these sensations and generate a color percept. These ideas were mainly taken on by Herman von Helmholtz, who saw them as a specific application of Müller's Law.

3. While Young believed the brain perceived all typically in terms of these three primary colors , Ewald Hering proposed that it was more sensible for the visual system to record differences among the levels of color detection. He proposed the existence of specifically three opponent circuits: red-green, blue-yellow, and black-white, which he believed to be a necessary to the perception of color.

4. As such, the historical context of this debate provides an interesting view into the development of knowledge regarding visual perception. While trichromatic theory explains and delineates the way in which the retina detects color, color opponency describes the mechanisms by which this information is processed and encoded by other parts of the visual system. Modern techniques and strategies have given scientists a better understanding of these processes and the debate has largely been reconciled (Swanson et al., 2003). Humans specifically have three distinct cone classes that contain different opines, named S, M, and L, which have peak sensitivities to different wavelengths of light and play a fundamental role in the detection of hue before any further processing. Some researchers few decades back have discovered that knocking in the gene for L- opsin allowed a colorblind monkey to be able to detect the full range of visible colors . On the other hand, color opponent receptive fields have been documented in the lateral geniculate nucleus for some time, even though the cones themselves may not be sensitive to opponency (Young et al., 1807). Additional research and analysis has shown that opponency can be set up very early in the visual process—at the level of retinal ganglion cell circuitry—and may rely on cellular morphology.

5. Trichromatic theory is connected in the present day with the names of Young and Helmholtz. But in the current scenario or in this century before Young it had already become a widespread and intensely discussed issue in color science. There are certain core statements about trichomancy (a) that trichromatic theories were so successful because their validity and assessment was strikingly demonstrated by the new technique of three‐color printing, (b) that trichromacy was believed typically to be a property of light and therefore seemed to contradict Newton's theory, (c) that the assumptions made to majorly reconcile both theories remained unsuccessful, and (d) that Young's interpretation of trichromacy as being a consequence of the structure of our visual system was so inconvenient to contemporary scientific thought that another 50 years had to pass before it was accepted(Young et al.,1807

6. A initial example of its use is the detection of fruit, such as cherries or raspberries, in foliage, and judgment of their degree of ripeness. Full trichromatic vision, is majorly based on long-wavelength (L), middle-wavelength (M) and short-wavelength (S) sensitive visual pigments, and is unique to primates among mammals. These pigments were mainly separated into individual cone photoreceptors. Other mammals usually have an S pigment in a small proportion of cones plus another pigment in the middle-wavelength region of the spectrum. This may cater them with an ability to distinguish colors along a blue-yellow dimension, but the details are uncertain. In any event, primates appear to have typically developed a highly sophisticated visual system capable of detecting both the borders between objects and their surface characteristics, such as color and brightness.

7. There are studies concerning with the development of ideas about color vision in humans, especially from a biological viewpoint; an intriguing overview from a more psychophysical perspective can be found in Mollon . Views of human color vision are closely bound up with theories about the nature of light, especially at the beginnings of color science in the 16th to 19th centuries. At that time there was no clear distinction between the properties of light itself, the typical properties of the eye and retina (i.e., the presence of the three pigments in three cone types with associated postreceptoral mechanisms) and color percepts which arise at a higher level in the brain, such as the long-range effects like color contrast, in which the color of one field is affected by the color of the surrounding area. The resolution of these issues has garnered a substantial challenge and many major figures in science and letters have attempted contributions, not always successfully. Physicists were responsible for main advances in color science until into 19th century, and this review begins with an overview of theories of the physical nature of light after Newton, who set color science in motion by publication of the Opticks (Young et al.,1807).

8. REFERNCE Journal of Research in Forensic Medicines and Biotechnology, Theories of Color Vision Theory, S. Sreeremya,2018.Vol(1):1,1-8.