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 883 records · Page 49Linked to original sources

PubMed1992

Neon flank and illusory contour: interaction between the two processes leads to color filling-in.

Two aspects of neon color spreading, local color spreading (neon flank) and illusory contour, were investigated by dichoptic viewing. Neon flank was not observed under appropriate dichoptic stimulation, suggesting that input to the process for local color spreading is based on monocular configuration. However, illusory contours were formed according to the interocularly combined configuration rather than according to each monocular configuration, suggesting that input to the process responsible for illusory contours should be ocularly-nonselective and binocular, rather than monocular. The possibilities of artifacts such as those arising from interocular rivalry were appropriately eliminated, and thus, it is tentatively concluded that the process underlying local color spreading is monocularly driven, whereas the process underlying illusory contours is binocularly driven. Furthermore, a new demonstration is presented that indicates that interocularly-induced illusory contours 'capture' and extend the monocularly-induced local color spreading, resulting in global color spreading (neon color spreading). These results support our hypotheses that neon color spreading involves two separable processes in the early visual processing, the feature detection process (for local color spreading) and the illusory contour process, and that these two processes interact with each other at later stages of cortical processing. The relation of local color spreading and illusory contours to surface separation is also discussed.

Adult↗

PubMed2005

Spatial balance of color triads in the abstract art of Piet Mondrian.

We examined the interactive contribution of the color and size of the three areas occupied by the primary colors red, yellow, and blue in adaptations of abstract compositions by Mondrian to the perceived weight of the areas and the location of the balance centers of the compositions. Thirty-six art stimuli were created by experimentally changing the colors in the three areas of six original works so that the resulting five variations and the original constituted the six possible spatial arrangements of the three colors in the three locations. In experiment 1, design-trained and untrained participants determined the location of the balance center of each composition seen on a computer screen and rated the apparent weight or heaviness of each color area. In experiment 2, untrained participants determined the location of the balance centers of the compositions when projected to their actual size. It was found that, for both trained and untrained participants, the perceived weight of a color, especially red and yellow, varied as a function of the size of the area it occupied. Furthermore, participants in both experiments perceived shifts in the locations of the balance centers between the originals and their altered versions. Only the trained participants, however, perceived significant shifts in balance centers among the five variations of the compositions, demonstrating their superior sensitivity to the contribution of color to balance structure. Taken together, the findings demonstrate the existence of a color-area-weight relationship among color triads in abstract displays and the influence of this relationship on color balance in abstract compositions.

Adult↗

PubMed1996

Primate photopigments and primate color vision.

The past 15 years have brought much progress in our understanding of several basic features of primate color vision. There has been particular success in cataloging the spectral properties of the cone photopigments found in retinas of a number of primate species and in elucidating the relationship between cone opsin genes and their photopigment products. Direct studies of color vision show that there are several modal patterns of color vision among groupings of primates: (i) Old World monkeys, apes, and humans all enjoy trichromatic color vision, although the former two groups do not seem prone to the polymorphic variations in color vision that are characteristic of people; (ii) most species of New World monkeys are highly polymorphic, with individual animals having any of several types of dichromatic or trichromatic color vision; (iii) less is known about color vision in prosimians, but evidence suggests that at least some diurnal species have dichromatic color vision; and (iv) some nocturnal primates may lack color vision completely. In many cases the photopigments and photopigment gene arrangements underlying these patterns have been revealed and, as a result, hints are emerging about the evolution of color vision among the primates.

Animals↗

PubMed1996

A note on adults' color-emotion associations.

The color-emotion associations of undergraduate students were analyzed. Twenty men and 20 women were asked to complete a self-administered questionnaire in which they listed their favorite color, the major color they were wearing, their emotional responses to colors, and the reasons for their choices. Responses showed that bright colors elicited mainly positive emotional associations, and dark colors elicited mainly negative emotional associations. Women responded more positively than men to bright colors, and they also responded more negatively to dark colors. Comparisons are made between the color-emotion associations of children and those of adults. The reasons for the color-emotion associations are discussed.

Adult↗

PubMed1997

Color-Word Stroop test performance across the adult life span.

In the Color-Word Stroop test (CWST), the basic task is to name the ink color of rows of XXXs, and performance in this condition is compared with performance in naming the ink-color of color words under conditions where word meanings and ink colors mismatch or are incongruent (e.g., the word red printed in green ink). The present study investigated whether Stroop test interference, defined as the cost associated with ink-color naming in the incongruous stimulus condition versus in the basic color-naming condition, provides positive evidence for a kind of processing qualitatively different than that which is required for color naming or for word reading. Does the pattern of age-related differences in Stroop interference force the conclusion that the incongruous condition taps a qualitatively different kind of processing than that required for color naming or for word reading? We gave the CWST to 310 healthy adults. Their performance in each condition of the test replicates and extends previous findings. Structural equation modeling of the data showed a significant, direct link between age and performance in the latent factor associated with the incongruent condition. However, this direct link with age produced a relatively small increase in the model's fit; it amounted to only a .024 increase in the proportion of variance explained in the incongruent condition. In light of this small direct influence due to age, the most parsimonious explanation of our findings is that age effects in Stroop interference are due to age-related slowing (which is also indexed by color naming and by word reading) primarily; the findings do not provide evidence for a qualitatively different kind of processing that declines with age.

Adolescent↗

PubMedDate not supplied

An fMRI version of the Farnsworth-Munsell 100-Hue test reveals multiple color-selective areas in human ventral occipitotemporal cortex.

Studies of patients with cerebral achromatopsia have suggested that ventral occipitotemporal cortex is important for color perception. We created a functional magnetic resonance imaging (fMRI) version of a clinical test commonly used to assess achromatopsia, the Farnsworth-Munsell 100-Hue test. The test required normal subjects to use color information in the visual stimulus to perform a color sequencing task. A modification of the test requiring ordering by luminance was used as a control task. Subjects were also imaged as they passively viewed colored stimuli. A limited number of areas responded more to chromatic than achromatic stimulation, including primary visual cortex. Most color-selective activity was concentrated in ventral occipitotemporal cortex. Several areas in ventral cortex were identified. The most posterior, located in posterior fusiform gyrus, corresponded to the area activated by passive viewing of colored stimuli. More anterior and medial color-selective areas were located in the collateral sulcus and fusiform gyrus. These more anterior areas were not identified in previous imaging studies which used passive viewing of colored stimuli, and were most active in our study when visual color information was behaviorally relevant, suggesting that attention influences activity in color-selective areas. The fMRI version of the Farnsworth-Munsell test may be useful in the study of achromatopsia.

Adaptation, Physiological↗

PubMed2002

Broiler skin and meat color changes during storage.

The importance of poultry skin and meat color (both absolute and variations in color) in the market place have been well established. It has also been reported that these colors change over time. With the development of computer-assisted vision grading systems, the changes in skin and meat color during and after processing have become important, based on calibrations and assessment values based on color. Four independent experiments were conducted to determine the pattern of color change in broiler skin and meat during processing and storage. Skin color change was measured on subscald (57 C) and semiscald (50 C) breast skin surfaces and on breast and leg meat, on the carcass and following deboning and packaging. A reflectance colorimeter was used to determine lightness (L*), redness (a*), and yellowness (b*) at 20-min intervals for the first 3 h, at 30-min intervals between 3 and 8 h, hourly between 8 and 12 h, and daily up to 8 d postmortem. Results clearly show that color values for both skin and meat changed dramatically for the first 6 h postmortem, after which the changes were less pronounced. The skin from semiscalded birds showed less change than the skin from subscalded birds. These results indicate that on-line vision systems need to take into account the dramatic changes in skin and meat color during the first 6 h postmortem, after which the color changes may be less important.

Animals↗

PubMed1998

Intratumoral vascularity of experimentally induced VX2 carcinoma: comparison of color Doppler sonography, power Doppler sonography, and microangiography.

RATIONALE AND OBJECTIVES: Tumor vascularity is useful for characterizing tumors and determining tumor management. The recent development of power Doppler sonography has enhanced the sensitivity of color Doppler imaging in the detection of blood flow because of low power noise and less angle dependence. The purpose of this study was to compare the capability of color and power Doppler sonography with that of microangiography for showing tumor vascularity of VX2 carcinoma. METHODS: Color and power Doppler sonography was performed on VX2 carcinomas in the rabbit thighs, and their findings were correlated with those of microangiography. For qualitative analysis, tumor vascularity was categorized into four items including distribution of tumor vessels, crowdedness of vessels, small vessels, (> or = 0.1 mm), and micro-vessels (< 0.1 mm). Tumor blood flow signals of color Doppler sonography and power Doppler sonography were graded as 3, 2, 1, and 0 and were compared with tumor vascularity on microangiography. For quantitative analysis, percentages of tumor vascular area per tumor area on each study were compared. RESULTS: The mean scores of tumor vascularity on power Doppler sonography were 2.87, 2.73, 2.93, and 2.73 in tumor vascular distribution, crowdedness of vessels, small vessels, and micro-vessels, respectively. Those on color Doppler sonography were 2.4, 2.2, 2.8, and 1.67, respectively. Power Doppler sonography was statistically superior to color Doppler sonography in displaying tumor vascular distribution (P < 0.05) and micro-vessels (P < 0.01). The means and medians of percentages of tumor vascular area per tumor area were 22.7% and 23.5% on microangiography, 17.9% and 21.4% on color Doppler sonography, and 36.4% and 34.7 % on power Doppler sonography, respectively. Percentages of tumor vascular area per tumor area on both color Doppler sonography (r = 0.70) and power Doppler sonography (r = 0.84) were well correlated with those on microangiography. CONCLUSIONS: Power Doppler sonography can demonstrate the tumor vascularity on microangiography relatively well, however, it tends to overestimate the blood flow signals. Color Doppler sonography may have some limitations in imaging tumor vascular distribution and micro-vessels and tends to underestimate tumor vascularity, but can display the blood flow direction. Therefore, power Doppler and color Doppler sonography could complement each other in demonstrating the tumor vascularity.

Angiography↗

PubMed2000

An imaging system with calibrated color image acquisition for use in dermatology.

We propose a novel imaging system useful in dermatology, more precisely, for the follow-up of patients with an increased risk of skin cancer. The system consists of a Pentium PC equipped with an RGB frame grabber, a three-chip charge coupled devices (CCD) camera controlled by the serial port and equipped with a zoom lens and a halogen annular light source. Calibration of the imaging system provides a way to transform the acquired images, which are defined in an unknown color space, to a standard, well-defined color space called sRGB. sRGB has a known relation to the CIE1 XYZ and CIE L*a*b* colorimetric spaces. These CIE color spaces are based on the human vision, and they allow the computation of a color difference metric called CIE deltaE*ab, which is proportional to the color difference, as seen by a human observer. Several types of polynomial RGB to sRGB transforms will be tried, including some optimized in perceptually uniform color spaces. The use of a standard and well-defined color space also allows meaningful exchange of images, e.g., in teledermatology. The calibration procedure is based on 24 patches with known color properties, and it takes about 5 minutes to perform. It results in a number of settings called a profile that remains valid for tens of hours of operation. Such a profile is checked before acquiring images using just one color patch, and is adjusted on the fly to compensate for short-term drift in the response of the imaging system. Precision or reproducibility of subsequent color measurements is very good with (deltaE*ab) = 0.3 and deltaE*ab < 1.2. Accuracy compared with spectrophotometric measurements is fair with (deltaE*ab) = 6.2 and deltaE*ab < 13.3.

Calibration↗

PubMed2001

Comparison of color of resin composites of white and translucent shades with two shade guides.

PURPOSE: The purpose of this study was to compare the color of resin composites of white, translucent, and conventional shades with shade guides, based on the analysis of the color distribution of shade guides. The influence of color measuring mode, specular component included (SCI) or excluded (SCE), was also determined. MATERIALS AND METHODS: The labial portions of shade guide tabs (Vita and Chromascop) were polished flat with up to 2400-grit SiC paper. Color coordinates were measured according to CIE L*a*b* color scale on a reflection spectrophotometer with both the SCE and SCI modes. The color coordinates of white, translucent, and conventional shades of two brands of resin composites were measured and compared with those of the shade guides. RESULTS: There was no logical order in the color distribution of the two shade guides. The color of white and translucent shades of resin composites was located on the low CIE a* and CIE b* value area. The CIE L*, a*, b* values of resin composite with the same color designations were different, depending on the brand of material. The color difference (deltaE*) of shade guides by the measuring mode (SCE vs. SCI) was between 3.2 and 6.5.

Color↗

PubMed1995

Common pitfalls of endovaginal color Doppler flow imaging.

Endovaginal color Doppler flow imaging is a relatively new technique that combines gray-scale sonography with duplex Doppler and color Doppler flow techniques. However, such imaging is associated with multiple pitfalls. Technical errors are caused by improper setting of the color flow parameters. The color velocity scale, color priority, color gain, color sensitivity, and color wall filter should be adjusted to optimize color flow information. Technical errors may result in false diagnosis of ovarian torsion, malignancy, and ectopic pregnancy. Errors in interpretation result from an inability to identify and correctly characterize tissue vascularity. Such errors include failure to distinguish placental from luteal flow and failure to characterize adnexal masses accurately. In addition, functional ovarian cysts may demonstrate increased vascularity throughout the menstrual cycle and simulate cancer. Recognition of the common pitfalls of endovaginal color Doppler flow imaging and integration of clinical and sonographic features will reduce misinterpretation and improve diagnostic accuracy.

Artifacts↗

PubMed1996

Power versus conventional color Doppler sonography: comparison in the depiction of vasculature in liver tumors.

PURPOSE: To compare power and conventional color Doppler sonography in the depiction of the intratumoral vasculature of hemangiomas, hepatocellular carcinomas (HCCs), and metastases of the liver. MATERIALS AND METHODS: Thirty-two patients with liver tumors (12 hemangiomas, 11 HCCs, and nine metastases) were prospectively evaluated with power and conventional color Doppler sonography by using a 2-4-MHz convex probe with 2-MHz Doppler frequency. Power Doppler sonography was performed with a 75%-88% gain. Conventional color Doppler sonography was performed with a 55%-75% gain and a pulse repetition frequency of 700 Hz. Power Doppler signals and color Doppler signals interrogated in one plane were analyzed by two radiologists, who subjectively rated power Doppler sonography as superior, equal, or inferior to color Doppler sonography. RESULTS: Overall, power Doppler sonography was superior to color Doppler sonography in 18 patients and equal in 14 (P < .01). In hemangiomas, power Doppler sonography was superior to color Doppler sonography in 10 patients and equal in two (P < .01). In HCCs, power Doppler sonography was superior to color Doppler sonography in four patients and equal in seven (P > .05). In metastases, power Doppler sonography was superior to color Doppler sonography in four patients and equal in five (P < .05). CONCLUSION: Power Doppler sonography is more sensitive than color Doppler sonography in the depiction of the vasculature of liver tumors, particularly in hemangiomas.

Adult↗

PubMed1990

A new, small-color-difference equation for dental shades.

Traditionally, dental-shade-guide standards are designated in terms of Munsell hue (H), value (V), and chroma (C). However, delta E color differences proposed as ADA tolerances for shade guides are in the CIE L*a*b* system. The purpose of this study was to evaluate a new color-difference equation, delta EM = C delta H/5 + 7 delta V + 4 delta C for estimation of small color differences by Munsell parameters. The published values of the Bioform shade-guide tooth colors determined with a Beckman spectrophotometer were used. Color differences among 276 combinations of the 24 Bioform shade-guide colors were calculated with Eq. 1, with use of the Munsell notation, and also with the CIE L*a*b* equation for delta E. An estimate of the accuracy of Eq. 1 was 0.41 delta E units when delta E CIE was below 4.0. The Vita shade-guide colors were determined with a Beckman spectrophotometer. This data set contained 16 samples, and 120 combinations were used for calculation of color difference. An estimate of the accuracy for this set of data was 0.35 delta E units when delta E CIE was less than 4.0. The new color-difference equation provides a means for estimation of delta E CIE L*a*b* color difference between dental shades with Munsell notation. This equation will be useful for estimation of small delta E CIE L*a*b* values for shade-guide teeth that are designated in terms of Munsell notation.

Color↗

PubMed2005

Vascular basis of mucosal color.

BACKGROUND: Besides the color of the teeth the color of the alveolar gingiva plays a crucial role in esthetic rehabilitation in dento-alveolar treatment. Whereas nowadays the color of the teeth can be determined exactly and individually, the specific influence of the red color of the gingiva on treatment has not been assessed yet. The aim of this study was to evaluate the vascularization as the basis for gingival esthetics. METHODS: Standardized photographs of defined areas of the alveolar gingiva in operated and non-operated patients were taken and assigned to groups with same characteristics after color comparisons. In addition, histologic and immunohistologic analyses of gingival specimens were performed for qualitative and quantitative assessment of vessels and vascularization. Finally, colors and number of vessels were correlated. RESULTS: Our results demonstrated three different constellations of colors of the alveolar gingiva in healthy patients. The operated patients could not be grouped because of disparate depiction. There was a clear correlation between color and vessel number in the alveolar gingiva. CONCLUSION: Our investigations revealed the connections between vascularization and gingival color. Recommendations for specific change or even selection of colors based on the results cannot be given, but the importance of vascularly based incision lines was demonstrated.

Color↗

PubMed1994

Evidence for separate pathways for color and luminance detection mechanisms.

We measure threshold versus contrast (TvC) functions for chromatic (red-green) and luminance sine-wave-grating stimuli for (1) the detection of luminance in the presence of color contrast and (2) the detection of color in the presence of luminance contrast. We find that, although these crossed TvC functions both display a dipperlike shape, their facilitation differs from that found for standard uncrossed dipper functions (luminance on luminance or color on color contrast). Their facilitation disappears (cross condition 1) or is reduced (cross condition 2) by randomized presentation of the phase of the test and the mask, and the remaining facilitation (cross condition 2) displays no spatial tuning. We argue that these crossed facilitatory interactions cannot be explained by detection mechanisms with common inputs from color and luminance contrast (a nonindependence of transduction), and we present evidence that instead they reflect the use of local cues in the stimuli. We also measure the luminance-luminance TvC function in the presence of a fixed suprathreshold color contrast. The results demonstrate that, even when the color contrast produces a masking of the luminance thresholds, luminance-luminance facilitation still occurs. Thus the opposing effects of masking and facilitation can occur simultaneously. Furthermore, while luminance-luminance facilitation occurs independently of color contrast, masking can be produced by either contrast. This suggests that masking and facilitation have different underlying origins. Similar results are found for the color detection thresholds in the presence of a luminance pedestal. We conclude that there are separate pathways for the detection of color and luminance contrast, each with no input from the other contrast. We suggest that the cross masking reflects divisive interactions between these pathways that is restricted to high contrasts.

Color Perception↗

PubMed2005

Spatial processing in color reproduction.

We consider the reproduction of color subject to material and neighborhood constraints. By "material constraints," we mean any constraints that are applied to the amount of ink, lights, voltages, and currents that are used in the generation of color. In the first instance we consider the problem of reproducing a target color constrained by maximum additive color signals, such as in the phosphorescence process in a cathode ray tube. In the second instance we consider the more difficult problem of reproducing color subject to constraints on the maximum primary color variations in a (spatial) neighborhood. We introduce the idea of adjacent color variance (ACV) and then attempt to reproduce colors subject to an upper bound on the ACV. An algorithm that is suitable for this task is the method of vector space projections (VSP). In order to use VSP for constrained color reproduction, we use a novel approach to linearize nonlinear CIE-Lab space constraints. Experimental results are furnished that demonstrate that using the ACV as a bound helps to reduce reproduction artifacts in a color image.

Algorithms↗

PubMed1988

Color preference in pigeons: stimulus intensity and reinforcement contingency effects in the avoidance of blue stimuli.

In a procedure intended to determine color preference in pigeons (which partially replicated Catania, Owens, & von Lossberg, 1983), two keys were illuminated by different colors drawn from a set of amber, red, green, or blue stimuli; this was followed by the presentation of grain when either of the two colors was pecked. The grain was illuminated alternately across trials with the colors presented on the keys. In Experiment 1 the intensity of the color stimuli used was not equalized, whereas in Experiment 2 the intensity of the colors was equalized. The low preference for blue found in Experiment 1, as measured by differential key pecking, was not found in Experiment 2. The discriminability of the intensity-equalized colors was confirmed in Experiment 2a, in which equal-intensity color discrimination problems were presented. In Experiment 3, as in Catania et al. (1983), a response-independent reinforcement schedule was used, but with intensity-equalized colors. In contrast to Experiment 2, very low preference for blue was found here and in Experiment 4, which used a within-subject procedure. These findings suggest that pigeon color preference may be a function of intensity, but all controlling variables have not as yet been identified.

Animals↗

PubMed2002

Impact of the continuous infusion of Levovist on color Doppler sonography in portal hypertension.

OBJECTIVE: This study was undertaken to investigate to what extent continuous infusion of a galactose-based microbubble contrast agent (Levovist) allows evaluation of the portal vascular system in patients with portal hypertension and for whom baseline unenhanced color Doppler sonography was nondiagnostic. SUBJECTS AND METHODS: We performed color Doppler sonography at baseline and during IV Levovist infusion (4 g, 300 mg/min). First, we measured the duration of portal vein visualization during Levovist infusion in 15 patients in whom unenhanced color Doppler sonography failed to show the portal confluence from a subcostal view. This duration of improved portal conspicuity was termed "diagnostic window." We then compared in 30 patients enhanced color Doppler sonographic findings with conventional imaging methods, including portography (n = 14), helical CT (n = 4), or gadolinium-enhanced MR angiography (n = 12), and we recorded the investigator's confidence in the color Doppler sonographic result before and after Levovist infusion. RESULTS: The diagnostic window achieved by the Levovist infusion was 13.6 +/- 0.9 min. At baseline, color Doppler sonography was nondiagnostic in 19 patients. The diagnostic confidence level was low in all the remaining 11 patients. During Levovist infusion, color Doppler sonography remained nondiagnostic only in two of 30 patients. The confidence level was low in five patients and high in 23 patients. In 26 of these 28 patients, echo-enhanced color Doppler sonographic findings were confirmed by reference methods. CONCLUSION: The continuous infusion of Levovist achieved a sufficient echo enhancement from the portal vascular bed and allowed a valid diagnostic color Doppler sonographic examination in portal hypertensive patients for whom color Doppler sonography would otherwise be nondiagnostic.

Adult↗