Color individual perceptions

INDIVIDUAL PERCEPTIONS OF COLOR AND BRIGHTNESS AND STANDARDIZATION PROBLEMS... 

Olfactory receptors have been a subject of great interest (9). Much that has been postulated was done by analogy to the sense of sight in which there are a limited number of receptor types and, as a consequence, only three primary colors. Thus attempts have been made to recognize primary odors that can combine to produce all of the odors that can be perceived. Evidence for this includes rough correlations of odors with chemical stmctural types and the existence in some individuals having specific anosmias. Cross-adaptation studies, in which exposure to one odorant temporarily reduces the perception of a chemically related one, also fit into this hypothetical framework. Implicit in this theory is the idea that there is a small number of well-defined odor receptors, so that eventually the shape and charge distribution of a specific receptor can be learned and the kinds of molecular stmctures for a specified odor can be deduced. 

In the preceding section, we presented principles of spectroscopy over the entire electromagnetic spectrum. The most important spectroscopic methods are those in the visible spectral region where food colorants can be perceived by the human eye. Human perception and the physical analysis of food colorants operate differently. The human perception with which we shall deal in Section 1.5 is difficult to normalize. However, the intention to standardize human color perception based on the abilities of most individuals led to a variety of protocols that regulate in detail how, with physical methods, human color perception can be simulated. In any case, a sophisticated instrumental set up is required. We present certain details related to optical spectroscopy here. For practical purposes, one must discriminate between measurements in the absorbance mode and those in the reflection mode. The latter mode is more important for direct measurement of colorants in food samples. To characterize pure or extracted food colorants the absorption mode should be used. 

Nevertheless, a mutual understanding about colors does work because conunon rules have been implemented by education, habituation, socially approved behavior, and properties that appear to individuals simultaneously, e.g., the vertical signal order of traffic lights. However, those rules are of limited value when color perception is the base for aesthetic appreciation as is the case for many industrial products and food products. In order to meet the demands of as many consumers as possible, producers look for a standard consumer who is most representative of the group. This requires establishment of a reliable measurement procedure that can be reproduced easily and be adapted to the various conditions under which it is applied light conditions, more or less opaque or translucent objects, object surface structures, etc. These measurement procedures were created more than a century ago and have... 

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. 

The visual hallucinations are often composed of extremely vivid colors of geometric patterns, such as cones, spirals, or cobweb-Uke structures. Other types of hallucinations are possible. A true hallucination involves the belief by the individual that the (altered) sensations and perceptions actually represent reality. However, generally the person abusing LSD and related drugs retains the ability to test reality versus illusion and knows that the experience is not real. Thus, the... 

The three drugs, LSD, mescaline, and psilocybin are commonly called hallucinogens because of their ability to alter consciousness such that the individual senses things that are not present. They induce, often in an unpredictable way, perceptual symptoms, including shape and color distortion. Psychosis-like manifestations (depersonalization, hallucinations, distorted time perception) have led some to classify these drugs as psychotomimetics. They also produce somatic symptoms (dizziness, nausea, paresthesias, and blurred vision). Some users have reported intense reexperiencing of perceptual effects (flashbacks) up to several years after the last drug exposure. 

The emphasis on control in certain color applications has resulted in tighter color tolerances. Color tolerances need to be realistic so they are achievable when considering the variables introduced by people, products, and instruments. The acceptable limits should not be set at the minimum limit of what a human observer can perceive. Added to this is the visual nonuniformity that exists for both perceptible and acceptable limits. Human observers do not respond equally to all colors. Hopefully, a uniform color difference equation could be available that adjusts the perceptibility and acceptability limits for individual colors. 

Students will interpret how color relativity affects perception of an individual color. 

Indeed, after a maturation period of 18 months, no significant differences were seen between the wines obtained without the yeast inoculums, either if they were aged in vinsantaia or at a constant temperature of 18 °C, except for the honey character and the color intensity. Similarly, also inside the cluster of wines obtained with both the yeast inoculum and the addition of madre there were no differences found in the perception of individual sensory attributes. However, the wines from the yeast-inoculated fermentation with the addition of madre were perceived to be more acidic, astringent, bitter, and viscous than the non-inoculated wines when they were aged in the cellar at constant temperature (18 °C). In contrast, there were no significant differences among the wines aged under the traditional conditions (vinsantaia). 

Successful visual color matching requires a good understanding of the nature of color, how color is perceived, the influence of the physiological and psychological processes of color perception, the human element variability, and the ability to evaluate or assess an individual s color acuity. Next, it is important to define and... 

Color perception. The photoreceptor rhodopsin (right), which absorbs light in the process of vision, consists of the protein opsin and a bound vitamin A derivative, retinal. The amino acids (shown in red) that surround the retinal determine the color of light that is most efficiently absorbed. Individuals lacking a light-absorbing photoreceptor for the color green will see a colorful fruit stand (left) as mostly yellows (middle). 

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

Figure 6.22 Field of vision of the right eye displaying the areas of individual color perception.

In all apphcations of color measurement, the primary objective is to produce a color data history close to the originally perceived color situation (1-3). Practicing this idea is key to successful color measurements. Human color perception varies with individuals but is second nature to all of us in every conceivable situation. Most of this section is devoted to some of the practical problems and solutions of color measurements based on this circumstance. 

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