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PubMed1998

Sensory and instrument-measured ground chicken meat color.

Instrument values were compared to sensory perception of ground breast and thigh meat color. Different patty thicknesses (0.5, 1.5, and 2.0) and background colors (white, pink, green, and gray), previously found to cause differences in instrument-measured color, were used. Sensory descriptive analysis scores for lightness, hue, and chroma were compared to instrument-measured L* values, hue, and chroma. Sensory ordinal rank scores for lightness, redness, and yellowness were compared to instrument-generated L*, a*, and b* values. Sensory descriptive analysis scores and instrument values agreed in two of six comparisons using breast and thigh patties. They agreed when thigh hue and chroma were measured. Sensory ordinal rank scores were different from instrument color values in the ability to detect color changes caused by white, pink, green, and gray background colors. Instrument values agreed with sensory scores for lightness only when white and pink backgrounds were used. Instrument and sensory methods agreed when a* values and redness scores were compared using each of the backgrounds. The sensory panel did not detect differences in yellowness found by the instrument when samples on white and pink backgrounds were compared to samples on green and gray backgrounds. A majority of panelists (84 of 85) preferred samples on white or pink backgrounds. Red color of breast patties was associated with freshness. Reflective lighting was compared to transmission lighting using patties of different thicknesses. Sensory evaluation detected no differences in lightness due to breast patty thickness when reflective lighting was used. Increased thickness caused the patties to appear darker when transmission lighting was used. Decreased transmission lighting penetrating the sample made the patties appear more red. Reflective lighting made thigh patties appear lighter. Lightness decreased when thigh patty thickness increased with both reflective and transmission lighting. Transmission lighting made the thigh patties appear more yellow as patty thickness increased.

Analysis of Variance↗

PubMed1996

Visual pigment gene structure and the severity of color vision defects.

Rearrangements of the visual pigment genes are associated with defective color vision and with differences between types of red-green color blindness. Among individuals within the most common category of defective color vision, deuteranomaly, there is a large variation in the severity of color vision loss. An examination of specific photopigment gene sites responsible for tuning photopigment absorption spectra revealed differences that predict these variations in the color defect. The results indicate that the severity of the defect in deuteranomalous color vision depends on the degree of similarity among the residual photopigments that serve vision in the color-anomalous eye.

Blotting, Southern↗

PubMed2005

Color of scents: chromatic stimuli modulate odor responses in the human brain.

Color has a profound effect on the perception of odors. For example, strawberry-flavored drinks smell more pleasant when colored red than green and descriptions of the "nose" of a wine are dramatically influenced by its color. Using functional magnetic resonance imaging, we demonstrate a neurophysiological correlate of these cross-modal visual influences on olfactory perception. Subjects were scanned while exposed either to odors or colors in isolation or to color-odor combinations that were rated on the basis of how well they were perceived to match. Activity in caudal regions of the orbitofrontal cortex and in the insular cortex increased progressively with the perceived congruency of the odor-color pairs. These findings demonstrate the neuronal correlates of olfactory response modulation by color cues in brain areas previously identified as encoding the hedonic value of smells.

Adult↗

PubMed1986

Analysis of the retinex theory of color vision.

If color appearance is to be a useful feature in identifying an object, then color appearance must remain roughly constant when the object is viewed in different contexts. People maintain approximate color constancy despite variation in the color of nearby objects and despite variation in the spectral power distribution of the ambient light. Land's retinex algorithm is a model of human color constancy. We analyze the retinex algorithm and discuss its general properties. We show that the algorithm is too sensitive to changes in the color of nearby objects to serve as an adequate model of human color constancy.

Algorithms↗

PubMed1990

Task-dependent color discrimination.

When an observer's ability to discriminate colored objects is estimated from the variability in color matches, the observer inspects adjacent visual fields carefully and makes considered judgments. Color discrimination does not always take place under such viewing conditions. When color video displays are used in time-critical applications (e.g., head-up displays, video control panels), the observer must discriminate among briefly presented targets seen within a complex spatial scene. We compare color-discrimination thresholds by using two tasks. In one task the observer makes color matches between two halves of a continuously displayed bipartite field. In a second task the observer detects a color target in a set of briefly presented objects. The data from both tasks are well summarized by ellipsoidal isosensitivity contours. The fitted ellipsoids differ both in their size, which indicates an absolute sensitivity difference, and orientation, which indicates a relative sensitivity difference.

Calibration↗

PubMed1991

Large color differences and selective attention.

Similarity data for large color differences, obtained with triadic comparisons, are presented. Approximately 63,000 judgments are collected. We have compared the performance of the CIELUV, the CIELAB, and the Optical Society of America's [symbol; see text] jg color spaces, using three different color sets and two instructions. For color sets containing large color differences in the isoluminant plane, the [symbol; see text] jg color space outperforms the CIELUV and CIELAB spaces. We also investigated the effects of selective attention and conclude that, for judgments of large color differences, selective attention leads to significant changes in the relative contribution of the brightness dimension on the one hand and the hue and saturation dimensions on the other hand.

Adult↗

PubMed1996

Effects of lights of different color temperature on the nocturnal changes in core temperature and melatonin in humans.

A variety of types of artificial illumination has recently become available, differing in the quality of illumination and range of color temperature. In our previous studies we found that in subjects with normal color vision the nocturnal fall in core temperature and the increase of urinary melatonin excretion were suppressed by bright blue or green light, but not by bright red or dim lights. The aim of our present study was to examine from the view point of chronobiology whether the lights of different color temperature often used in everyday life may affect core temperature and urinary melatonin secretion differently. Experiments were carried out on five subjects with normal color vision. They were exposed for 5 hr (from 21:00 h to 2:00 h) to two kinds of bright (1000 lx) light of different color temperature (6500 K, 3000 K) with dim (50 lx) light as a control; after exposure they slept in darkness. Our main results were as follows: The light with a high color temperature of 6500 K more strongly suppressed the nocturnal fall of the core temperature and the nocturnal increase of melatonin secretion than the light with a low color temperature of 3000 K. This difference was particularly evident for core temperature during the sleep period following experimental illumination.

Adult↗

PubMed2005

A study of hue identification in the hue circle of the HSB color space.

The purpose of the present research was to explore the relationship between the sensory difference in hues in the hue circle of the HSB color space and their included angles in identification tasks. In the experiment, the two colors were presented separately, and the test subjects judged whether the two colors were the same or different. Five hues, called Standard Stimulus Hues and the most saturated colors in the hue circle of the HSB color space, were discussed. These are hue 0 degrees, hue 72 degrees, hue 216 degrees, and hue 288 degrees in the HSB color space. The Just Identifiable Angle refers to the included angle between a specific standard hue and the hue which cannot be identified separately and which is the furthest from the standard hue in the hue circle of the HSB color space. Analysis gave a significant main effect of standard hue. The Just Identifiable Angles for hue 72 degrees and hue 288 degrees did not differ significantly, but their Just Identifiable Angles were discernibly lower than those for the other three hues. The Just Identifiable Angle of hue 144 degrees was significantly lower than those for hue 0 degrees and hue 216 degrees. In addition, the Just Identifiable Angle for hue 0 degrees was noticeably larger than the one for hue 216 degrees, so the final outcome might show that the Just Identifiable angles of the standard hues are not equal.

Adolescent↗

PubMed1975

Color preferences, extraversion, and neuroticism of art students.

Color preferences of 190 art students (Götz & Götz, 1974, 1975) were compared with the corresponding scores on extraversion (E) and neuroticism (N). It was found that the preferences of a group of 27 highly gifted young artists were different from preferences of average and less gifted Ss who had little or no artistic practice. In the latter group extraverts and ambiverts mainly preferred primary and secondary colors (light clear and dark clear tones included), while introverts preferred tertiary colors (earth colors) and achromatics. However, in the group of highly gifted Ss no significant differences between positive and negative rankings in both color categories were found. Neuroticism had no effect on color preferences; this holds for introverts and extraverts and for each single color.

Adult↗

PubMedDate not supplied

A sweep VEP test for color vision deficits in infants and young children.

PURPOSE: Color vision testing in young children typically is precluded by the motor and cognitive skills required by standard tests; yet this information can be useful for diagnosis and counseling in many conditions. The purpose of this study is to evaluate a visual evoked potential (VEP) method for assessing red-green color vision anomalies in pediatric patients. METHOD: The relative chromatic luminance (C = R/R + G) of a rapidly reversing red-green checkerboard was varied across a wide range within a short viewing period (10 sec). Swept-parameter VEP methods were used to measure the cortical response to the range of C presented. RESULTS: Individuals with normal color vision exhibit a VEP response that exceeds noise levels across all values of C, often with an amplitude minima near the photopic equiluminant point (C = 0.5). Results from children with established protan and deutan color vision anomalies show loss of VEP amplitude and phase at values of C consistent with the respective color defect. A patient with achromatopsia showed a generalized depression of VEP response across all values of C tested. CONCLUSION: Color sweep VEP techniques appear promising for the clinical assessment of color status in pediatric patients.

Child↗

PubMed2006

Effect of enamel shades on color of layered resin composites.

The purpose of this study was to evaluate the effect of the covering enamel layer of various thicknesses on the color of layered resin composites (LRC). To this end, the CIELAB parameters of the following were evaluated: underlying base (ULB: 2.0 mm of body shade + 3.0 mm of opaque shade), inherent color of the enamel shade (4.0 mm of enamel shade + ULB), and LRC disks (0.5, 1.0, 2.0, 3.0 mm of enamel shade + ULB) of Filtek Supreme (FS, 3M) and Gradia Direct (GD, GC). To assess the effect of the enamel layer on the color of LRC, color difference between ULB and LRC was calculated. With FS, the enamel layer had no major effect on the color of LRC--regardless of thickness. With GD, the enamel layer had a significant effect on the color of LRC, even if the thickness was only 0.5 mm. The difference in enamel layer effect between the two products could be attributed to the difference in color characteristics of the two enamel shades.

Acrylic Resins↗

PubMedDate not supplied

Human-eye versus computerized color matching.

This project compared the difference in color matching between human-eye assessment and computerized colorimetry. Fifty dental personnel were asked to color match Vita Lumin shade tabs to seven different randomly arranged test tabs from the Z100 shade guide. All evaluators were blinded to the shades of the test tabs and were asked to match only body shade of the Vita Lumin tab to the middle third or body of each test tab. The results obtained were subsequently computed into L*a*b* values and compared with results obtained by computerized colorimetry. Results indicate that the difference in color matching between human-eye assessment and computerized colorimetry is shade dependent. Discrepancy was significant for b* coordinates for shades A1 and B2 and L* and b* coordinates for shade C4. For all shades evaluated, color difference between human-eye and computerized color matching is perceivable under clinical settings, as delta E values are greater than 3. There is a need for correction factors in the formal specification of the color-matching software due to the discrepancy between human-eye and computerized colorimetric color matching.

Color↗

PubMedDate not supplied

[Computer method for evaluating disorders in sense of color].

A new method for evaluating disorders in the sense of color has been developed and offered for practice. A total of 340 patients with diseases of the retina and optic nerve and 80 normal subjects were examined. The results indicate that different conditions of examination, selection of combination by the color, brightness, and deepness of the stimulus and background allow detection of decreased sensitivity of one, two, or three color perceptors (disorders in sense of color--color blindness) and permit a quantitative evaluation of functional disorders in the color channels of visual system. The new method can be used in the diagnosis of the initial pathological processes of different origin, involving the cone system at any level of visual route and associated with acquired disorders in color vision.

Color Perception↗

PubMed2002

[A study on examination of color vision with pattern-visual evoked potential].

OBJECTIVE: To understand the specific nature of the color and brightness components of the human visual evoked potential and explore the possibility of an objective method for examining the color vision. METHOD: The transient VEP was measured in normal subjects and persons with deficient color vision by multichannel electro-physiological apparatus. In the experiment, four kinds of reversal checkerboard patterns are simulated by the computer software technology as stimuli. The patterns included black-white (95% contrast), isoluminance chromatic checkerboards red-white, green-white, red-green (100% saturation), which were 25 ' in visual angle and alternated at a rate of 0.8 Hz. The main component, P (1) wave, was analyzed. RESULTS: (1) The normal subject group: The P (1) latencies in four conditions were obtained in terms of the length of latencies, the ordinal of P (1) latencies (from short to long) was as follows: red-white < black-white < red-green < green-white. There were very significant differences among the four latencies (P < 0.01). The P (1) amplitudes elicited with the black-white were higher than those with chromatic ones. But among the P(1) amplitudes elicited with chromatic checkerboards there were no difference. (2) The group with deficient color vision: There were no significant differences in the P(1) latencies and amplitudes elicited with the four stimuli. The length of latencies with black- white stimulus was the shortest. Red-green blindness as well as deuteranopia had no response to green stimulus but did to red or red-green stimulus. (3) Between the two groups, there were no differences in the P (1) latencies, but the P (1) amplitudes of persons with deficient color vision elicited with the chromatic stimuli were obviously lower. CONCLUSION: The results show that it is feasible to use chromatic VEP for examining congenital color vision deficiency, especially for red-green blindness and deuteranopia. At present, there is lack of quantitative and qualitative results of color VEP examination.

Adolescent↗

PubMed2000

[Effect of titanium substructure on color of porcelain-fused-to-titanium restoration].

OBJECTIVE: To study the effect of titanium substructure on color of porcelain-fused-to-metal restoration. METHODS: Standard samples of Dentsply DETREY-Carat and Tibond porcelain fused-to-metal restorations were made. Color Parameters were tested by cs-5 spectrophotometer. Statistic analysis was done and the color differences were calculated. RESULTS: Most of color parameters were found to be statistically significant at the P < or = 0.05 level at substructure layer. But no statistical significance existed after putting opaque and dentin porcelain. The values of color difference between two groups at opaque and dentin porcelain layers were all smaller than 1.5. CONCLUSIONS: Titanium substructure had no visually apparent effect on final color of porcelain-fused-to-metal restoration. There was no perceived color difference between corresponding shade of two Dentsply porcelain systems (DETREY-Carat and Tibond).

Color↗

PubMed1992

Genotype-phenotype relationships in human red/green color-vision defects: molecular and psychophysical studies.

The relationship between the molecular structure of the X-linked red and green visual pigment genes and color-vision phenotype as ascertained by anomaloscopy was studied in 64 color-defective males. The great majority of red-green defects were associated with either the deletion of the green-pigment gene or the formation of 5' red-green hybrid genes or 5' green-red hybrid genes. A rapid PCR-based method allowed detection of hybrid genes, including those undetectable by Southern blot analysis, as well as more precise localization of the fusion points in hybrid genes. Protan color-vision defects appeared always associated with 5' red-green hybrid genes. Carriers of single red-green hybrid genes with fusion in introns 1-4 were protanopes. However, carriers of hybrid genes with red-green fusions in introns 2, 3, or 4 in the presence of additional normal green genes manifested as either protanopes or protanomalous trichromats, with the majority being protanomalous. Deutan defects were associated with green-pigment gene deletions, with 5' green-red hybrid genes, or, rarely, with 5' green-red-green hybrid genes. Complete green-pigment gene deletions or green-red fusions in intron 1 were usually associated with deuteranopia, although we unexpectedly found three carriers of a single red-pigment gene without any green-pigment genes to be deuteranomalous trichromats. All but one of the other deuteranomalous subjects had green-red hybrid genes with intron 1, 2, 3, or 4 fusions, as well as several normal green-pigment genes. The one exception had a grossly normal gene array, presumably with a more subtle mutation. Amino acid differences in exon 5 largely determine whether a hybrid gene will be more redlike or more greenlike in phenotype. Various discrepancies as to severity (dichromacy or trichromacy) remain unexplained but may arise because of variability of expression, postreceptoral variation, or both. When phenotypic color-vision defects exist, the kind of defect (protan or deutan) can be predicted by molecular analysis. Red-green hybrid genes are probably always associated with protan color-vision defects, while the presence of green-red hybrid genes may not always manifest phenotypically with color-vision defects. Four subjects who were found to have 5' green-red hybrid genes in addition to normal red- and green-pigment genes had normal color vision as determined by anomaloscopy. These were discovered among a group of 129 Caucasian males who had been recruited as volunteers for a vision study.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Sequence↗

PubMed1992

The True Daylight Illuminator (TDI): a less expensive source of illumination for color vision screening.

This experiment was designed to examine the feasibility of using the True Daylight Illuminator (TDI) as an illumination option for conducting color vision screening with the Ishihara Test(s). The MacBeth Easel Lamp was designed to provide proper illumination for performing color vision screening with a variety of pseudoisochromatic (PIC) plate tests including the Ishihara. However, over the years, the MacBeth Lamp has become so expensive that many smaller programs cannot afford to purchase one. This problem has promoted the use of alternate light sources that have had a deleterious effect on test results and in some instances contributed to job discrimination. Recently the MacBeth Division of the Kollmorgan Corporation discontinued the manufacture of the MacBeth Lamp due to lack of demand. Thus, it is important to find an inexpensive illumination option for conducting color vision screening. Two groups of subjects were used to compare test results for the 24-plate edition of the Ishihara Test using both the MacBeth Lamp and the True Daylight Illuminator. The first group contained 45 subjects with inherited color defective vision. The second group was made up of 30 color normals. The Nagel anomaloscope was used to confirm the color vision status of the subjects in both groups. Statistics to test the significance of differences between group means clearly demonstrated that there were no significant differences between the mean error scores of the two groups for these two pieces of equipment. Thus, it was concluded that the TDI can be used in lieu of the MacBeth Easel Lamp for screening color vision with the Ishihara test.

Adolescent↗

PubMed2005

[Effect of thickness and shade of porcelain of ceramometal restorations on color of gingival porcelain].

OBJECTIVE: The purpose of this study was to evaluate the color changes of gingival porcelain through varying thickness and shade of porcelain of ceramometal restorations. METHODS: In this study a spectrophotometer (PR-650) was used for color analysis. The color changes of dentin porcelain and gingival porcelain with three varied thickness (0.3 mm, 0.6 mm and 0.9 mm) were investigated. In addition, the color variances of Shofu vintage porcelain shade A2, A3 and B2 were tested. RESULTS: The results showed that decreased L * value of ceramometal restorations and increased a * value were due to the increase of the gingival porcelain thickness, color measurements showed the same trend as the increased dentin porcelain thickness and the opaque and dentin porcelain with different color affected the appearance of gingival porcelain. CONCLUSION: The color of gingival porcelain would be changed with the differences of thickness and shade of porcelain of ceramometal restorations.

Color↗