The perception of color

The perception of color is subjectively developed in the mind of an individual, and consequently different people can perceive a given color in various ways. Such variability in interpretation causes great difficulty in the evaluation of color-related phenomena, leading to problems in making objective judgements. The development of quantitative methods for color determination was undertaken to eliminate the subjectivity associated with visual interpretative measurements. 

Because Ecstasy can produce mild hallucinations, it is often referred to as a psychedelic drug having effects similar to those of LSD. Unlike other psychedelic drugs, however, Ecstasy does not produce vivid perceptual and visual distortions, like walls and ceilings turning into liquid. Rather, the perception of colors, sound, music, and touch appears to be intensified by Ecstasy. In addition, the perception of time may be slowed or otherwise altered. 

The light-sensitive protein complex in the rods, rho-dopsin, consists of 1 l-c/s-retinal bound as a Schiff s base to a protein, opsin. Rhodopsin is an integral constituent of membranes that form a stack of disks at one end of the cell. Cone cells, which are responsible for the perception of color, contain similar complexes in infoldings of the plasma membrane. 

Blurred vision. Three hypnotic subjects responded positively to this condition two hypnotic subjects and the simulator responded with schizoid withdrawal. Those that responded positively responded in terms of the primacy of color and light over form, and compared their perceptions of the world with impressionist paintings. One subject and the simulator responded in terms of an inability to make contact with anybody the last subject responded with a blunting and dulling of thought processes. All subjects lost some sensation in non-visual modalities. When the perception of outlines alone was blurred, colors tended to stand out. Alan Watts (1962) has noted how the perception of form and the perception of color may really be the same, but the behavior patterns of these subjects do not support this point of view. 

The total amount of energy from the source is also an important factor in the perception of color. If the energy is too low, we are not able to see the full color results. If the energy is too high, we are blinded by the light. The ASTM standard D 1729-89 addresses the issue of level of illumination under section 5.1.2, Photometric Conditions this is an excellent practice to adopt for color laboratories as it focuses on the visual evaluation of color in a controlled environment (ASTM D 1979-89). 

Sildenafil has weak inhibitory effects on phosphodiesterase type V in the retina, leading to temporary changes in the perception of color hue and brightness. The importance of reversible changes in the electroretinogram observed in volunteers after sildenafil 100 mg, ascribed to inhibition of phosphodiesterase type 5 in the retina, is unclear (20-22). 

Relatively weak absorptions at wavelengths above 400 mn are snfficient to cause the perception of color. The color of woody tissue varies widely from off-white (e.g., aspen, birch), yellow (e.g., spruce, pine, fir), amber-orange (e.g., western hemlock, Douglas fir, red cedar, teak) and rich browns (walnnt). While some of this color is dne to tannins and other extractives, in most species the color originates from chromophores in the lignin. 

It follows that as birefringence rises so too will the difference in the optical reflectance of colour when viewed from different angles and also the perception of color will change as the degree of drawing increases. 

These items will all contribute to the color shifting as well as the light intensity that may affect the perception of color. 

Kaverman J. The perception of color. Plastics Decorat [trade journal—Peterson Publications] July/August 2008. 

The perception of color is complex, very individual, and could be categorized as... 

By 1931, CIE had developed one of the first mathematically defined color spaces, considering principally the perception of color. In 1993, commercial members... 

The variation of reflection from thin films (e.g., soap bubbles) of light of different wavelengths results in the perception of colors and is a fanuliar example of scattering interference. Less familiar is the variation in reflection of a particle beam, outlined above. However, once we recognize the wave nature of matter, we must expect particles to manifest the same sort of wave properties we associate with light. 

A number of publications are available which address in detail the perception of color, the methods used to systematize color, the measurement of color and color difference, and other color phenomena [6-14]. This chapter will touch on each of these briefly. 

At this point, we have seen the experimental evidence and the theories that developed around the nature of light and the fact that so-called white, or achromatic, light is anything but We must now ask how is it that we see the colors inherent in white light without the use of a modifying prism, and more importantly, how is it that we can see any color at all To answer these questions, we must look at the three components necessary for the perception of color the source of light, the object being observed, and the observer. 

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