SEARCH · PubMed Health

Results for “Color”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 793 records · Page 44Linked to original sources

PubMed1994

Flow characteristics in benign and malignant gynecologic tumors using transvaginal color flow Doppler.

OBJECTIVE: To assess flow characteristics of benign and malignant gynecologic tumors by transvaginal color flow Doppler. METHODS: Records of the Ultrasound Laboratory, Women's Cancer Center, University of Minnesota were analyzed retrospectively. Gray scale findings were recorded as either "diagnostic" or "nondiagnostic." Color flow assessment was performed on intratumor vessels or ovarian and/or uterine arteries. Flow was recorded as either "absent" or "present." Spectral analysis allowed determination of the systolic, diastolic, and mean velocities and calculation of the pulsatility and resistance indices. Malignancy was then predicted based upon color flow findings alone, with malignant tumors demonstrating increased color flow and a pulsatility index of at most 1.0 or a resistance index of at most 0.4. Color flow Doppler findings were then recorded as "giving additional useful information" that either confirmed questionable gray scale findings or changed the gray scale sonographic diagnosis, or as "not giving additional information" over the gray scale diagnosis. RESULTS: Two hundred thirty-one patients had gray scale sonography, and 167 also had color flow Doppler performed. Gray scale sonographic findings were sufficient to make a diagnosis in 156 (93%) of the scans. Color flow Doppler findings added useful information in 49 scans (30%). Increased color flow was highly significant (P < .0001), as was the calculated pulsatility index (P < .02) and resistance index (P < .008), in distinguishing benign from malignant tumors. Ovarian and uterine artery and intratumor assessments of the systolic, diastolic, and mean velocities were not significantly different between the benign and malignant tumors. Regression analysis confirmed the presence or absence of color flow as an independent predictor of malignancy or benignity (P < .0001). CONCLUSIONS: Our large study confirms the overall accuracy of gray scale scanning. When used alone, color flow Doppler--although specific--lacks sensitivity and predictive value as an independent predictor of malignancy. When findings were combined with those obtained from gray scale scanning, sensitivity, specificity, and predictive value were improved to acceptable levels. Significant differences existed between benign and malignant tumors for calculated pulsatility index and resistance index, but neither was sufficiently sensitive, specific, or predictive to be used alone as sole criteria of malignancy prediction. Other flow indices studied (systolic, diastolic, and mean velocities) in general did not differ significantly between groups. Physicians should be cautioned against using color flow findings alone for clinical decision making. We recommend a multi-institutional study to investigate the multiple vascular assessments to determine the role of color flow Doppler in the preoperative prediction of pelvic tumors and in screening for gynecologic abnormality.

Adult↗

PubMed1988

Functional anatomy of macaque striate cortex. III. Color.

Using spatially diffuse stimuli (or sinusoidal gratings of very low spatial frequency), levels of 14C-2-deoxy-d-glucose (DG) uptake produced by color-varying stimuli are much greater than those produced by luminance-varying stimuli in macaque striate cortex. Such a difference in DG results is consistent with previous psychophysical and electrophysiological results from man and monkey. In DG experiments with color-varying gratings of low and middle spatial frequencies, or with spatially diffuse color variations, DG uptake was highest in the cytochrome oxidase blobs, as was also seen with low-spatial-frequency luminance gratings. High-spatial-frequency, color-varying uptake patterns were shifted to cover both blob and interblob regions in a manner similar to that of the patterns obtained with middle-spatial-frequency luminance stimuli. However, in no instance did chromatic gratings produce uptake restricted to the interblob regions, as with the pattern seen with the highest-spatial-frequency luminance gratings. Thus, DG uptake is relatively higher in the interblob regions when comparing luminance with color-varying gratings that are otherwise similar. It was also possible to show DG evidence for receptive-field double-opponency in the upper-layer blobs, but color sensitivity in layer 4Cb appears single-opponent. The DG results suggest that color sensitivity is also high in the lower-layer (layers 5 + 6) blobs, and that many layer 5 receptive fields are double-opponent. Striate layers 4Ca and 4B-appeared color-insensitive in a wide variety of DG tests; this supports the idea of a color-insensitive stream running from the magnocellular LGN layers through striate layers 4Ca and 4B to extrastriate areas MT and V3. There was also a major effect due to wavelength: long and short wavelengths produced much more uptake than did middle wavelengths, even when all colors were equated for luminance and saturation. No variation with eccentricity was seen in cortical color sensitivity, at least between 0 degrees and 10 degrees.

Animals↗

PubMed1985

[Color change in dental tissue as a sign of thermal damage].

The appearance of hard human tissue after thermal damage permits certain conclusions to be drawn with regard to fire parameters. In addition to morphological destruction, the change in color of dental tissues like enamel, dentine, and cement is also important. We studied teeth extracted from 330 human males and females under well-defined time and temperature conditions. Using the DIN and RAL color indexes, the color phenomenon was evaluated on the basis of the amount of glowing obtained when the teeth were heated. It is easiest to determine the color change in cement, as no calculus or hindering plaques are on the root surface. In addition to this, destruction of the tooth root takes place only during extreme combustion conditions. Determining the dentine color is more difficult and is possible only after the enamel splits. Also, the different dentine thicknesses hinders the observation of color. When the enamel was tested, it was found that the differences in color caused by high temperatures are unimportant. Moreover, the enamel burst into small particles. The effect we observed regarding the anthracite lustre using low temperatures was typical, and the best results were obtained in dental roots with eight color scales. All three dental hard tissues have in common that the variations in color appear regularly and successively according to ascending temperature or duration of time: natural dental color, black, brown, blue, grey, white, and pink. In these processes, the temperature and combustion time are inversely proportional to the velocity of color change. The literature is discussed that deals with temperature- and time-dependent color phenomena of dental hard tissues destroyed as a result of thermal damage.

Burns↗

PubMed1991

Hormonal control of sex and color change in the stoplight parrotfish, Sparisoma viride.

The stoplight parrotfish, Sparisoma viride, changes sex from female to male. In most cases, sex change is accompanied by dramatic change in coloration, from the female-like "initial phase" coloration to "terminal phase" coloration that is associated with males. However, some males do not change color at the same time they change sex, becoming female-mimic males (termed initial phase males). Using radioimmunoassays validated here for use with plasma from S. viride, we examined the hormonal profile of stoplight parrotfish undergoing sex change. As predicted, females were characterized by undetectable levels of 11-ketotestosterone (11KT), moderate levels of testosterone, and high levels of 17 beta-estradiol (E2). Fish that were found histologically to be undergoing sex change had elevated levels of 11KT and decreased levels of E2. Testosterone appeared to be unaffected. Males had the highest levels of 11KT and testosterone and low levels of E2. Because initial phase males eventually change color, we were able to take blood samples from males (sex confirmed histologically) before, during, or after color change. Thus, we also examined the hormonal correlates of color phase change. Initial phase males, like females, had undetectable levels of 11KT, moderate levels of testosterone, and significantly higher levels of E2 than either terminal phase males or males with transitional coloration. During color transition, 11KT levels rose sharply and levels of E2 declined. Males with terminal phase coloration had the highest levels of 11KT and testosterone and low levels of E2. Finally, administration of 11KT induced precocious sex change and color change in functional adult females. These findings suggest that 11KT plays a key role in instigating natural sex and color change, but that once sex change is complete, 11KT is not necessary for spermatogenesis or spawning behavior.

Animals↗

PubMedDate not supplied

Do Doppler color flow algorithms for mapping disturbed flow make sense?

It has been suggested that a major advantage of Doppler color flow mapping is its ability to visualize areas of disturbed ("turbulent") flow, for example, in valvular stenosis or regurgitation and in shunts. To investigate how various color flow mapping instruments display disturbed flow information, color image processing was used to evaluate the most common velocity-variance color encoding algorithms of seven commercially available ultrasound machines. In six of seven machines, green was reportedly added by the variance display algorithms to map areas of disturbed flow. The amount of green intensity added to each pixel along the red and blue portions of the velocity reference color bar was calculated for each machine. In this study, velocities displayed on the reference color bar ranged from +/- 46 to +/- 64 cm/sec, depending on the Nyquist limit. Of note, changing the Nyquist limits depicted on the color reference bars did not change the distribution of the intensities of red, blue, or green within the contour of the reference map, but merely assigned different velocities to the pixels. Most color flow mapping algorithms in our study added increasing intensities of green to increasing positive (red) or negative (blue) velocities along their color reference bars. Most of these machines also added increasing green to red and blue color intensities horizontally across their reference bars as a marker of increased variance (spectral broadening). However, at any given velocity, marked variations were noted between different color flow mapping instruments in the amount of green added to their color velocity reference bars.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗

PubMed2002

Molecular phylogeny of the Puerto Rican Lepidocyrtus and Pseudosinella (Hexapoda: Collembola), a validation of Yoshii's "color pattern species".

Color pattern was one of the most important characters used to diagnose species in the genus Lepidocyrtus until the introduction of chaetotaxy to Collembola taxonomy. Chaetotaxy confirmed most species diagnoses based only on color patterns, but a number of populations with distinct pigmentation patterns have been found to be identical in all other morphological characters. The absence of individuals showing intermediate color patterns prompted Yoshii to suggest that, despite chaetotaxic identity, populations with distinct color forms represent valid species (implying reproductive isolation and therefore biological species) in what he designated as "color pattern species." In Puerto Rico Lepidocyrtus biphasis, L. dispar, and L. caprilesi show a remarkable variation in pigmentation and as a group include 11 different color forms. Here I present a phylogenetic analysis of the cytochrome oxidase I gene (COI) in 17 species of Lepidocyrtus and Pseudosinella, including 11 species and 10 color forms of Puerto Rican Lepidocyrtus, to test Yoshii's color pattern species concept. The analysis shows large genetic distances between species defined based on morphology alone (morphospecies) and between most color variants within morphospecies. The most often used calibration for the COI molecular clock (2.3% sequence divergence per million years) suggests that morphospecies diverged between 20 and 25 million years before present while color forms within morphospecies diverged between 8 and 19 million years ago. This indicates that changes in climate and sea levels during the Pleistocene were irrelevant to the speciation process in the Puerto Rican Lepidocyrtus. Examination of the genetic variation, phylogenetic relationships, and collection data in light of the biological and phylogenetic species concepts supports the hypothesis that most populations of morphospecies differing only in color pattern are distinct species, thus validating Yoshii's color pattern species concept. As a result it is suggested that morphological characters traditionally used in species diagnoses are very conservative indicators of genetic divergence, that the diversity of springtails has been greatly underestimated, and that studies concerned with identifying factors promoting speciation in Collembola could be misled if they do not include analysis of mitochondrial markers.

Animals↗

PubMed2004

Ecological genetics of adaptive color polymorphism in pocket mice: geographic variation in selected and neutral genes.

Patterns of geographic variation in phenotype or genotype may provide evidence for natural selection. Here, we compare phenotypic variation in color, allele frequencies of a pigmentation gene (the melanocortin-1 receptor, Mc1r), and patterns of neutral mitochondrial DNA (mtDNA) variation in rock pocket mice (Chaetodipus intermedius) across a habitat gradient in southern Arizona. Pocket mice inhabiting volcanic lava have dark coats with unbanded, uniformly melanic hairs, whereas mice from nearby light-colored granitic rocks have light coats with banded hairs. This color polymorphism is a presumed adaptation to avoid predation. Previous work has demonstrated that two Mc1r alleles, D and d, differ by four amino acids, and are responsible for the color polymorphism: DD and Dd genotypes are melanic whereas dd genotypes are light colored. To determine the frequency of the two Mc1r allelic classes across the dark-colored lava and neighboring light-colored granite, we sequenced the Mc1r gene in 175 individuals from a 35-km transect in the Pinacate lava region. We also sequenced two neutral mtDNA genes, COIII and ND3, in the same individuals. We found a strong correlation between Mc1r allele frequency and habitat color and no correlation between mtDNA markers and habitat color. Using estimates of migration from mtDNA haplotypes between dark- and light-colored sampling sites and Mc1r allele frequencies at each site, we estimated selection coefficients against mismatched Mc1r alleles, assuming a simple model of migration-selection balance. Habitat-dependent selection appears strong but asymmetric: selection is stronger against light mice on dark rock than against melanic mice on light rock. Together these results suggest that natural selection acts to match pocket mouse coat color to substrate color, despite high levels of gene flow between light and melanic populations.

Animals↗

PubMed2004

Dual-color photon-counting histogram.

We report on the development of dual-color photon-counting histogram (PCH) analysis. Dual-color PCH is an extension of regular PCH and considers the photon counts received in two detection channels instead of one. Because each detection channel records a different color, dual-color PCH distinguishes fluorescent species not only by differences in their brightness, but also according to their color. The additional discrimination by color increases the sensitivity of PCH in resolving a mixture of species considerably. Most dual-color fluorescence fluctuation experiments are performed on fluorophores with overlapping emission spectra. This overlap results in spectral cross talk between the detector channels, which reduces resolvability. Here, we demonstrate that dual-color PCH is able to resolve binary dye mixtures in the presence of cross talk from a single measurement without any additional information about the sample. We discuss the effect of sampling time on the fit parameters of dual-color PCH. Differences between dual-color fluorescence correlation spectroscopy and dual-color PCH will also be addressed. We quantitatively resolve a mixture of the two fluorescent proteins CFP and YFP, which is challenging because of the strong spectral overlap of their emission spectra. Dichroic mirrors are needed to direct the light into the two detection channels. We quantify the influence of these filters on dual-color PCH analysis and determine the optimal transition wavelength of the dichroic mirror for the CFP-YFP pair.

Algorithms↗

PubMed1999

Ultraviolet radiation-induced color shifts occurring in oil-pigmented maxillofacial elastomers.

STATEMENT OF PROBLEM: Oil-based pigments are added to a maxillofacial prosthesis either as base colorants present within the elastomer or as surface tints that are painted on with an adhesive. Color stability of the pigments and pigmented prosthetic materials on exposure to ultraviolet radiation are unknown. PURPOSE: This study measured DeltaE* color changes caused by ultraviolet radiation for materials colored with 5 oil pigments, applied either as base colorants (intrinsic) or surface tints (extrinsic) to a silicone elastomer. MATERIAL AND METHODS: One of 5 oil pigments was added to polydimethyl siloxane disks to serve as a base colorant (0.2 weight percent present throughout a 2 mm thick disk) or as a concentrated surface tint (2.0 weight percent concentrated in upper 0.3 mm thickness). Pigmented disks, along with pigment-only and elastomer-only control disks, were exposed to ultraviolet radiation for 400, 600 and 1800 hours. DeltaE* color changes were measured at baseline and for each time interval. RESULTS: Control samples underwent minimum color changes after 1800 hours (DeltaE* </= 2.0), whereas samples containing oil pigments as base colorants demonstrated a wide range of susceptibility to ultraviolet radiation, with the greatest changes occurring for pigments cadmium red, cadmium yellow, and yellow ochre (7.1 </= DeltaE* </= 9.4). Elastomers coated with the same oil pigments as concentrated surface tints demonstrated significantly lower color shifting after 1800 hours of radiation exposure (maximum DeltaE* = 4.2, P </= .05). CONCLUSION: Customizing a prosthesis with an oil-pigmented surface tint may reduce the incidence of color change, provided a sufficient amount of pigment is present.

Coloring Agents↗

PubMed2004

Color classification by chimpanzees (Pan troglodytes) in a matching-to-sample task.

We investigated chimpanzees' color classification using a matching-to-sample procedure. One of the two subjects had learned symbolic color names through long-term training, while the other had received less training and had a limited understanding of color names. The results showed similar distributions of classified colors in a color space, irrespective of the subjects' differential color-naming experience. However, the chimpanzee with little color-naming experience showed less stable classifications. These results suggest common features of color classification in chimpanzees, as well as the influence of color experience and/or the learning of color names on the stability of classification of colors.

Animals↗

PubMed2000

Visual and colorimetric lithium ion sensing based on digital color analysis.

A new optical analytical method, "Digital Color Analysis (DCA)", is proposed based on a digital color analyzer instead of the conventional optical methodology, "Spectrophotometry". The digital color analyzer is a hand-held-size instrument for measuring "colors", and it can transform the color information into numerical values, color library data, etc., that can be treated as analytical information. DCA gives us a more informative analytical method than spectrophotometry by treating colors as digital information. In addition, DCA can also simulate the optimum color variations for optimization of the visual sensor with computer assistance. By utilizing colors as digital information, colorimetric analysis that has been used for only semiquantitative analysis can serve as an accurate determination method. On the basis of DCA, we developed a plasticized PVC film optode and a paper optode for Li+ determination in saliva. After the optimization of color variation and the detection range for the Li+ measurements, the optode membrane gives colorless gray in the Li+ therapeutic range (at 10(-3) M) in saliva. Consequently, whether or not the optimum therapeutic Li+ concentration is maintained can be easily evaluated with these optodes. Especially, the sensing paper optode can be easily handled within a short measurement time (approximately 80 s) which is suitable for home use. Using the digital color analyzer with QxQy coordinates, a linear relation calibration curve can be obtained over the range from 10(-5) to 10(-1) M Li+, in which the analyzer can detect a concentration difference of approximately 0.1 mM Li+. For the near future, an accurate and simple analysis is needed for a health check at home that does not require going to a hospital. The optode based on DCA has great potential for this analytical purpose.

Analog-Digital Conversion↗

PubMed2006

Color vision but not visual attention is altered in migraine.

OBJECTIVE: To examine visual search performance in migraine and headache-free control groups and to determine whether reports of selective color vision deficits in migraine occur preattentively. BACKGROUND: Visual search is a classic technique to measure certain components of visual attention. The technique can be manipulated to measure both preattentive (automatic) and attentive processes. Here, visual search for colored targets was employed to extend earlier reports that the detection or discrimination of colors selective for the short-wavelength sensitive cone photoreceptors in the retina (S or "blue" cones) is impaired in migraine. METHOD: Visual search performance for small and large color differences was measured in 34 migraine and 34 control participants. Small and large color differences were included to assess attentive and preattentive processing, respectively. In separate conditions, colored stimuli were chosen that would be detected selectively by either the S-, or by the long- (L or "red") and middle (M or "green")-wavelength sensitive cone photoreceptors. RESULTS: The results showed no preattentive differences between the migraine and control groups. For active, or attentive, search, differences between the migraine and control groups occurred for colors detected by the S-cones only, there were no differences for colors detected by the L- and M-cones. The migraine group responded significantly more slowly than the control group for the S-cone colors. CONCLUSIONS: The pattern of results indicates that there are no overall differences in search performance between migraine and control groups. The differences found for the S-cone colors are attributed to impaired discrimination of these colors in migraine and not to differences in attention.

Attention↗

PubMed1965

COLORIMETRIC DETERMINATION OF COLOR OF AERIAL MYCELIUM OF STREPTOMYCETES.

Lyons, Allister J., Jr. (Northern Regional Research Laboratory, Peoria, Ill.) and Thomas G. Pridham. Colorimetric determination of color of aerial mycelium of streptomycetes. J. Bacteriol. 89:159-169. 1965.-For some time, streptomycete taxonomists have been seeking to describe more accurately the colors of aerial mycelium. Some of the descriptive systems involve many different color names and groups. Others combine many colors into a few groups. All the systems and methods leave much to be desired. To obtain an accurate description, a colorimeter with a reflectance attachment was used to examine streptomycete aerial mycelium of 37 strains, representing all of the major aerial mycelium color groups. Each color was characterized by three values: dominant wavelength in millimicrons, and purity and brightness in percentages. All colors of aerial mycelium were of low purity (< 25%). Most of the dominant wavelengths were in the yellow to yellow-green bands of the spectrum. Most of the color tabs matched visually with the streptomycete strains had purities of a higher value than those of the cultures. The reflectance instrument seems to allow an objective description, and its use may help to clarify the color problem with streptomycetes. It is concluded that present color descriptions are inadequate and that the significance of color in speciation requires critical examination.

Color↗

PubMed1977

A photometric study of the color of health gingiva.

An apparatus was developed that was found suitable for measuring gingival color in terms of reflectance at 6328 A. A total of 445 readings were taken on 95 Caucasian subjects in order to determine certain properties of healthy gingival color. It was determined that: 1. Healthy adult gingival color ranged in reflectance from 17% to 45% of the magnesium oxide standard, with a mean of 32%. 2. Gingival color of children was lighter than that of adults. The reflectance of children's gingiva ranged from 31% to 43%, with a mean of 35%. 3. Gingival color did not vary with the sex of the individual. 4. Gingival color was lighter in individuals with blonde hair than in individuals with brown hair. 5. Gingival color was darker in individuals with darker eye color. 6. Gingival color was lighter in individuals with geographic origins that are commonly related to lighter complexions. 7. Gingival color did not vary with age, within the adult range covered in this study. 8. Gingival color did not vary with the following physiological and physical factors: menstrual period, use of oral contraceptives, smoking habits, moistness or dryness of the gingiva, which side was measured, time of day, or time after toothbrushing, smoking a cigarette, eating an apple, or drinking a hot beverage.

Adult↗

PubMed2000

Evolution of color vision loss induced by occupational exposure to chemicals.

The evolution of occupationally induced color vision loss was studied in workers exposed to various chemicals. Exposure was evaluated by biological monitoring or personal air samplers, and color vision using the Lanthony D-15 desaturated panel (D-15 d). The effect of short-term interruption of exposure was studied in 39 Styrene (St) exposed workers: at a first examination a dose-related color vision loss was disclosed; a re-test performed after one month's interruption of exposure did not show any improvement of the effect. The evolution during longer periods was studied in another group of 30 St workers. Exposure and color vision were evaluated, then a follow-up was done 12 months later: the exposure was unmodified or slightly decreased in 20 subjects, and D-15 d outcomes remained unchanged, while St levels had increased and color vision loss progressed in the other 10. Similar results were obtained in 33 PCE exposed dry-cleaners: no change in color perception was observed in 14 workers whose exposure decreased, while in the other 19 a rise in PCE levels was followed by a significant color vision worsening. In 21 Hg exposed workers whose mean urinary excretion of Hg was threefold the BEI proposed by ACGIH, a dose-related impairment in color perception was observed. 12 months after a marked reduction of exposure, an almost complete recovery of the impairment was observed. Our data show that an increase in exposure can induce a worsening in color vision loss. A short interruption in exposure did not reduce the effect. A more prolonged reduction of dose reversed color vision loss in Hg exposed workers, while in solvent-exposed individuals the progression deserves further evaluation. D-15 d proved a useful test for studies on the evolution of color perception in workers exposed to eye-toxic chemicals.

Color Perception↗

PubMed2000

Clinical application of four and five-color flow cytometry lymphocyte subset immunophenotyping.

A 1995 survey of clinical flow cytometry laboratories in the United States determined that 63% of clinical laboratories used one or two-color, 33% used three-color, 4% used four-color, and none used five-color panels. We show the feasibility and advantages of acquiring routine clinical four-color, six-parameter and five-color, seven-parameter analysis on blood samples derived from a pediatric population. The panels were evaluated by comparing the following cell characteristics: size, internal structure, and up to five distinct fluorochrome-conjugated antibodies to cell surface antigens: CD3, CD16+CD56, CD19, CD8, and CD4. These samples were processed on a commercially available instrument without any special modifications. A comparison of two-color and four-color as well as four-color and five-color panel analysis showed no statistical difference between the groups. We propose that the five-color, single-tube panel will (1) eliminate the need for isotype controls; (2) the relative proportions of lymphocyte subpopulations may be used to validate the operator-defined window, replacing CD45; (3) eliminate the need to run a common factor, in order to establish and maintain a reproducible lymphocyte window between tubes; and (4) create a more complete clinical picture by generating 32 unique, mutually exclusive phenotypes (permutations). Our results show that it is feasible to acquire and integrate seven-parameter data. This may be a powerful tool for immunophenotyping cells in a modern clinical diagnostic cytometry laboratory.

Antigens, CD↗

PubMed2005

Influence of porcine liver esterase on the color of dental resin composites by CIEDE2000 system.

The objectives of this study were to evaluate the changes in color and color coordinates of dental resin composites after immersion in porcine liver esterase (PLE, 400 mU/mL; a substitute for salivary hydrolase) with CIEDE2000 color system, and to compare those with CIELAB color system. Color of resin composites was measured after immersion in PBS (phosphate buffered saline; control) or PLE up to nine weeks. Color difference (delta E00) and changes in lightness (L'), red-green parameter (a'), yellow-blue parameter (b'), and chroma (C') with CIEDE2000 system were compared. Correlation in the changes of color with CIEDE2000 and CIELAB systems was determined. Delta E00 values after a 9-week immersion in PLE were 0.7-2.8, which were not higher than those in PBS except for a few cases. Changes in b' and C' values after a 9-week immersion in PLE were generally lower than those in PBS, and were in the range of -4.0 to -0.1 and -4.0 to -0.1, respectively. Therefore, the influence of porcine liver esterase on the changes of color and color coordinates was negligible with CIEDE2000 color system. There was a significant correlation between color differences (delta E00 vs deltaE*ab) with CIEDE2000 and CIELAB systems [correlation coefficient (r) = 0.95, p < 0.01].

Animals↗

PubMedDate not supplied

Neuronal network simulating the simultaneous contrast of equiluminant colors.

A vector model for the simultaneous contrast of equiluminant colors is proposed. The main characteristics of simultaneous color contrast are associated with the interaction of the test and induction fields. The mechanisms of color contrast depend on the activity of neurons which subtract excitation arising in analogous neurons of the test and induction fields. Signals from the "subtractor" neurons pass via local inputs to "adder" neurons. Selective color detectors are excited by contributions from the adder neurons. When the induction and test fields are of identical color and their excitation vectors coincide, the color of the test field depends on neurons excited only in the test field, and the induction field has no effect on the color of the test field. When the test and induction fields are of different color tone or saturation, the color of the induction field affects the color of the test field such that the excitation vector of the test field diverges from the excitation vector of the induction field. This model can be used for analysis of neurophysiological and psychophysiological studies of color contrast.

Color Perception↗