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At least 127 records · Page 7Linked to original sources
PubMed1999

Color stability and colorant effect on maxillofacial elastomers. Part II: weathering effect on physical properties.

STATEMENT OF PROBLEM: The clinical life of a maxillofacial prosthesis averages about 6 months, before it needs to be refabricated. Degradation of the color and physical properties of the prosthesis are the principle reasons for replacement. PURPOSE: This second part of a 3-part in vitro investigation evaluated the change in physical properties of popular colorant-elastomer combinations as a result of weather exposure. MATERIAL AND METHODS: Fifteen dumbbell-shaped and 15 trouser-shaped specimens were fabricated for each of the 3 elastomers (Silastic medical adhesive type A, Silastic 4-4210, and Silicone A-2186) and 6 colorant combinations (dry earth pigments, rayon fiber flocking, artist's oil paints, kaolin, liquid cosmetics, and no-colorants) for a total of 540 specimens. The 15 dumbbell-shaped and trouser-shaped specimens of each elastomer colorant combination were separated into 5 of each shape among 3 test condition groups (control, time passage, and natural weathering). Control specimens were evaluated within 1 month of fabrication. The time passage group was sealed in glass containers and kept in the dark for 6 months before testing. The natural-weathering groups were placed on the roof of the dental school for 6 months and exposed to sunlight and weathering. Evaluations of hardness and tear strength were made on trouser-shaped specimens, and evaluations of the ultimate tensile strength and percentage elongation on dumbbell-shaped specimens. Physical property data for each elastomer-colorant combination were subjected to a 1-way analysis of variance to examine effects among the test conditions. When significant differences were observed, the Student-Newman-Keuls multiple range test was performed to identify differences in elastomer-colorant combinations among each test condition at a significance level of .05. RESULTS: Exposure to weathering and time changes of the physical properties of many colorant-elastomer combinations indicated that properties of a clinical prosthesis can change with time. CONCLUSION: The addition of colorants to the silicones altered the effects of weathering. In addition, the silicones were not as stable as previously assumed.

Analysis of Variance↗
PubMed2006

Transforming reflectance spectra into Munsell color space by using prime colors.

Independent researchers have proved mathematically that, given a set of color-matching functions, there exists a unique set of three monochromatic spectral lights that optimizes luminous efficiency and color gamut. These lights are called prime colors. We present a method for transforming reflectance spectra into Munsell color space by using hypothetical absorbance curves based on Gaussian approximations of the prime colors and a simplified version of opponent process theory. The derived color appearance system is represented as a 3D color system that is qualitatively similar to a conceptual representation of the Munsell color system. We illustrate the application of the model and compare it with existing models by using reflectance spectra obtained from 1,269 Munsell color samples.

Color↗
PubMed1998

Value of contrast-enhanced color Doppler sonography in diagnosing hepatocellular carcinoma with special attention to the "color-filled pattern".

PURPOSE: The purpose of this study is to evaluate the effectiveness of contrast-enhanced color Doppler sonography in the diagnosis of hepatocellular carcinoma (HCC), with special attention to the value of a "color-filled pattern." METHODS: Contrast enhancement with Levovist was performed on 30 liver tumors, including 21 HCCs, as part of phase II and III clinical trials. Detection of a "feeding artery" or a "color-filled pattern" with color Doppler sonography was interpreted as a positive finding for HCC. Angiography was also performed. RESULTS: A feeding artery was detected in 9 HCCs before contrast enhancement and 20 HCCs after. A color-filled pattern was seen in 14 HCCs after enhancement. A feeding artery was seen in only 1 non-HCC tumor, and a color-filled pattern was not seen in any non-HCC. The sensitivity and specificity of a feeding artery for the diagnosis of HCC were 95% and 89%, values similar to those of hepatic angiography. The sensitivity and specificity of a color-filled pattern were 67% and 100%, respectively. CONCLUSIONS: Contrast enhancement increases the detectability of a feeding artery and improves the sensitivity of color Doppler sonography for diagnosing HCC. A color-filled pattern is a highly specific finding in the diagnosis of HCC.

Adult↗
PubMedDate not supplied

Color Doppler flow imaging of hepatocellular carcinomas. Comparison with metastatic tumors and hemangiomas by three-step grading for color hues.

The role of color Doppler imaging was evaluated in differentiating hepatocellular carcinomas (HCCs) from metastases and hemangiomas by the amount of tumoral color signals. Intratumoral and peritumoral color signals were analyzed by a three-step grading system (grade 1 to 3) in 51 patients (32 HCCs, seven metastases, and 12 hemangiomas). Correlation of grading scores for intratumoral and peritumoral color signals was evaluated with the size of the tumors as well. HCCs demonstrated a higher grade of intratumoral color signals than did metastases or hemangiomas in all (p < 0.05) and biopsy-proved lesions (p = 0.0084); there was no significant difference in the degree of peritumoral color signals in all (p > 0.05) or 17 biopsy-proved HCCs (p = 0.2078) from the other tumor groups. In addition, the grade of both intratumoral and peritumoral color signals was not related with the tumor size in all groups (p > 0.05). In conclusion, color Doppler imaging provided a valuable role in the diagnosis of HCCs based on the qualitative analysis of the intratumoral color signals.

Adult↗
PubMed2002

Cues and strategies for color constancy: perceptual scission, image junctions and transformational color matching.

The identification of objects, illuminants, and transparencies are probably the most important perceptual functions of color. This paper examines the effects of perceptual scission, image junctions, color adaptation, and color correlations on identification. Simulations of natural illuminants, materials, and filters were used in a forced-choice procedure to simultaneously measure thresholds for identifying filters and objects across illuminants, and discrimination thresholds within illuminants. In the vast majority of the cases, if observers could discriminate within illuminants they could identify across illuminants. Since results were similar for identical color distributions, whether transparency cues like X-junctions were present or not, the primary cues for color identification were systematic color shifts across illuminants. These color shifts can be well described by three-parameter affine transformations, and the parameters can be derived from differences and ratios of mean chromaticities. A strategy based on post-transformation color matching predicts generally accurate identification despite perceptible color shifts, and also provides plausible reasons for those few conditions where identification thresholds are significantly higher than discrimination thresholds.

Color Perception↗
PubMed1997

Additive effect of luminance and color cues in generation of neon color spreading.

A series of experiments were designed to examine how luminance and color cues influence the occurrence of neon color spreading for the Ehrenstein pattern plus the cross pattern. The proportion of "see" responses for color spreading was obtained for different combinations of the luminance and color of the pattern components. The following were obtained. (1) Increase in the luminance of the inducing pattern and/or the color difference between the cross and the inducing pattern raised the proportion of "see" responses for color spreading. This implies that luminance and color signals additively contribute to the generation of the color spreading, but in different ways. (2) The "iso-spreading contours" for the generation of color spreading were determined on the two-dimensional isoluminant plane composed of the L-M and S-(L+M) axes. The contours were approximately described by rotated quadratic or ellipse functions. The additive interaction within the chromatic systems [the L-M system and the S-(L+M) system] was less significant than that across the luminance and chromatic systems. (3) The pattern of the experimental results could not be explained straightforwardly by existing models.

Color Perception↗
PubMed2006

The mere exposure effect is sensitive to color information: evidence for color effects in a perceptual implicit memory test.

Priming effects in perceptual tests of implicit memory are assumed to be perceptually specific. Surprisingly, changing object colors from study to test did not diminish priming in most previous studies. However, these studies used implicit tests that are based on object identification, which mainly depends on the analysis of the object shape and therefore operates color-independently. The present study shows that color effects can be found in perceptual implicit tests when the test task requires the processing of color information. In Experiment 1, reliable color priming was found in a mere exposure design (preference test). In Experiment 2, the preference test was contrasted with a conceptually driven color-choice test. Altering the shape of object from study to test resulted in significant priming in the color-choice test but eliminated priming in the preference test. Preference judgments thus largely depend on perceptual processes. In Experiment 3, the preference and the color-choice test were studied under explicit test instructions. Differences in reaction times between the implicit and the explicit test suggest that the implicit test results were not an artifact of explicit retrieval attempts. In contrast with previous assumptions, it is therefore concluded that color is part of the representation that mediates perceptual priming.

Adult↗
PubMed1999

Myocardial motion imaging: a new application of power color flow and frequency-based color flow Doppler in fetal echocardiography.

OBJECTIVE: Myocardial motion imaging is a new way of looking at the fetal heart using power color flow and frequency-based color flow Doppler to demonstrate heart wall movement in color. This study set out to assess the value of myocardial motion imaging in fetal echocardiography in a routine clinical setting. DESIGN: In our hospital, all patients at high risk of carrying a fetus with a cardiac abnormality are offered detailed ultrasound scanning, including fetal echocardiography, at 20 weeks' gestation. A prospective study was carried out over a 2-month period and, in addition to conventional fetal echocardiography, myocardial motion imaging was also carried out on all patients, by means of both power color flow and frequency-based color flow Doppler ultrasound. RESULTS: Myocardial motion imaging demonstrated fetal heart wall movement in 26 of the 27 patients. Myocardial motion imaging using power color flow gave a global view of fetal heart wall movement, demonstrating both atrial and ventricular contraction simultaneously. Myocardial motion imaging using frequency-based color flow Doppler demonstrated atrial and ventricular contractions separately. In addition, as the direction of fetal heart wall motion can be color coded, atrial contractions, ventricular relaxation and ventricular contraction were demonstrated, providing a functional assessment of fetal heart wall movement. Two cases of cardiac abnormality were also studied, one case of hypoplastic left heart syndrome and one case of atrioventricular septal defect. In both cases functional information was obtained using myocardial motion imaging, and the technique also highlighted the anatomical defect. CONCLUSIONS: Myocardial motion imaging produces both a global view of fetal cardiac anatomy and a functional assessment of individual chamber contraction in the normal and abnormal heart. It may prove to be a useful adjunct to conventional color flow Doppler assessment of the fetal heart.

Adolescent↗
PubMed2001

Perception of forbidden colors in retinally stabilized equiluminant images: an indication of softwired cortical color opponency?

In color theory and perceptual practice, two color naming combinations are forbidden-reddish greens and bluish yellows-however, when multicolored images are stabilized on the retina, their borders fade and filling-in mechanisms can create forbidden colors. The sole report of such events found that only some observers saw forbidden colors, while others saw illusory multicolored patterns. We found that when colors were equiluminant, subjects saw reddish greens, bluish yellows, or a multistable spatial color exchange (an entirely novel perceptual phenomena); when the colors were nonequiluminant, subjects saw spurious pattern formation. To make sense of color opponency violations, we created a soft-wired model of cortical color opponency (based on winner-take-all competition) whose opponency can be disabled.

Color Perception↗
PubMed2006

Performance of a color-difference formula based on OSA-UCS space using small-medium color differences.

An investigation of the color metrics and the complexity of the CIEDE2000 formula shows that CIELAB space is inadequate to represent small-medium color differences. The OSA-UCS (Uniform Color Space) Committee has shown that no space with uniform scale for large color differences exists. Therefore the practical way for color-difference specification is a color-difference formula in a nonuniform space. First, the BFD (Bradford University) ellipses are considered in the OSA-UCS space, and their very high regularity suggests a new and very simple color-difference formula at constant luminance. Then the COM (combined) data set used for the development of the CIEDE2000 formula is considered in the OSA-UCS space, and the color-difference formula is extended to sample pairs with a different luminance factor. The value of the performance factor PF/3 for the proposed OSA-UCS-based formula shows that the formula performs like the more complex CIEDE2000 formula for small-medium color differences.

Algorithms↗
PubMed1993

Color-naming and color-matching by preschool children as a function of visual field and sex.

The accuracy for both a color-naming and a color-matching task as a function of visual field and sex was investigated in preschool children. Subjects were 17 boys and 17 girls ranging in age from 4.4 to 5.6 yr. Each subject was tested on both tasks, for which the target stimuli were presented tachistoscopically. Accuracy measures for each task were obtained separately for both left and right visual fields. A two-factor (sex x visual field) analysis of variance with repeated measures on the visual-field factor showed a significant difference between the sexes on the color-naming task only. No significant difference between visual fields was found for either task. However, significant interactions between sex and visual field for both the color-naming and color-matching tasks were obtained. t tests for simple main effects showed a significant right visual-field advantage for girls in naming colors. Conversely, a significant left visual-field advantage for color-matching was found for boys. Also, on the color-matching task, significant sex differences were found for both visual fields when compared separately. Boys were more accurate for left and girls more accurate for right visual field. Boys performed in a more strongly lateralized fashion on the color-matching task than did the girls, supporting the notion of greater lateralization among males.

Age Factors↗
PubMed2000

Assessment of fresh pork color with color machine vision.

Currently, fresh pork color is visually evaluated using either the Japanese Pork Color Standards (JPCS) or the National Pork Producers Council Pork Quality Standards (NPPC) as a reference. Although useful, visual evaluation of meat color can vary with evaluator and may be quite expensive. In this study, three separate studies were used to compare the ability of color machine vision (CMV) and untrained panelists to evaluate pork color. Panels visually evaluated over 200 pork loin chops using either the JPCS or NPPC reference standards. Results from each panel were used to evaluate the ability of the CMV to sort pork loin chops based on the same criteria. Representative samples, typical of each color class, were used to train neural-network-based image processing software. After training, the CMV system was used to evaluate quality classes of pork samples based on color distribution. Classification by CMV was compared with the average panel score, rounded to the nearest integer. Training the CMV system using images of actual meat samples resulted in a stronger correlation to panel scores than training with either set of artificial color standards. Agreement between the CMV system and the panels was as high as 90%. Agreement between individual panelists and the integer panel average (52 to 85%) was less than that observed for CMV classification. Finally, the on-line performance of CMV using a laboratory conveyor system was simulated by repeatedly classifying 37 samples at a speed of 1 sample per second. Collectively, these results demonstrate that CMV is a rapid and repeatable means of evaluating pork color.

Animals↗
PubMed2000

Visual color and doneness indicators and the incidence of premature brown color in beef patties cooked to four end point temperatures.

An interlaboratory study was undertaken to assess the frequency that cooked color of ground beef patties appeared brown at internal temperatures of 52.7 degrees C (135 degrees F), 65.6 degrees C (150 degrees F), 71.1 degrees C (160 degrees F), and 79.4 degrees C (175 degrees F). In general, as internal cooked temperature of the patties increased, the following results were observed in the patties: (i) more brown meat color, (ii) less pink or red juice color, and (iii) more cooked texture. However, brown meat color occurred prematurely at the two lower internal temperatures (57.2 degrees C/135 degrees F and 65.6 degrees C/150 degrees F) that are insufficient to eliminate foodborne pathogens without holding times. The common consumer practice of freezing bulk ground beef, followed by overnight thawing in a refrigerator, led to substantial premature brown color in patties cooked from this product. In addition, at 71.1 degrees C (160 degrees F), recognized to be the lowest temperature for cooking ground beef safely in the home, meat color, juice color, and texture appearance were not fully apparent as doneness indicators. In fact, at no temperature studied did 100% of the patties appear done when evaluated by the criteria of no red or pink in the meat, no red or pink in the juices, or by texture appearance. Patties in this study were evaluated under a set protocol for forming the products, cooking, and viewing under the same lighting conditions. Other preparation conditions are possible and may produce different results. Thus, temperature to which patties have been cooked cannot be judged by color and appearance. This study provided the evidence to support the message to consumers regarding cooking of beef patties of "use an accurate food thermometer and cook beef patties to 160 degrees F (71.1 degrees C)" in place of messages based on consumer judgment of cooked color.

Animals↗
PubMedDate not supplied

Color changes of porcelain surface colorants resulting from firing.

Differential loss of chrome from surface colorants during firing can make the prediction of final porcelain color difficult. This investigation was undertaken to assess the color change of nine extrinsic colorants during firing. Colorants were applied to metal-ceramic substrates, and color was measured both before and after firing using a colorimeter. CIE LAB color coordinates were obtained as a measure of the direction and quantity of color change. Color change for yellow (delta E*ab = 4.00) was significantly greater than that for the other groups (delta E*ab = 0.41-1.25). Changes in L*a*b* values for yellow samples were toward those of the controls.

Analysis of Variance↗
PubMed2005

[The effect of colored syringes and a colored sheet on the incidence of syringe swaps during anesthetic management].

BACKGROUND: Syringe swap is an important problem in anesthetic care, causing harm to patients. We examined the effect of colored syringe and a colored sheet on the incidence of syringe swaps during anesthetic management. METHODS: We determined the color code. The blue-syringe contains local anesthetics; yellow-syringe, sympathomimetic drugs; and white-syringe with a red label fixed opposite the scale, muscle relaxants. The colored sheet displays the photographs of the syringe with drug name, dose and volume. The colored syringe and colored sheet were supplied for use from February 2004. We compared the incidence of syringe swaps during the period from February 2004 to January 2005 with that from February 2003 to January 2004. RESULTS: Although five syringe swaps were recorded from February 2003 to January 2004, in 5901 procedures, we encountered no syringe swaps from February 2004 to January 2005, in 6078 procedures. The colored syringe and colored sheet significantly decreased the incidence of syringe swaps during anesthetic management (P <0.05). CONCLUSIONS: The use of the sheet together with colored syringes can prevent syringe swaps during anesthesia.

Anesthesiology↗
PubMed2006

[Investigation of the function of the glass colorant on the machinable infiltrated ceramics color].

OBJECTIVE: To investigae the function of the glass colorant on the color of the machinable infiltrated ceramics(MIC). METHODS: Five kinds of glass with different colorant were infiltrated through the aluminous matrix by heating the components to 1 100 degrees C for 2 hours. The specimens surface was polished, and their thickness was 0.5 mm. RESULTS: The refractive index of the MIC infiltration glass was 1.59691 (587.6 nm, nd) . The most different parameter of the MIC color were L*, then a*, and b* had little difference . The parameters of the color space of MIC were: L*(64.55-71.46), a*(3.35-7.38), b*(10.00-12.41), Ca*b*(11.38-13.95), ha*b*(54.07-73.00). These were almost close to the color parameters of Vita In-ceram. CONCLUSION: This experiment proved that the glass colorant was changed the MIC color parameters, and the main function was on L*, then a*. The ceramic color was up to the requirement of clinic.

Aluminum Oxide↗
PubMed1983

Constitutional biases in early perceptual learning: I. Preferences between colors, patterns, and composite stimuli of colors and patterns in genetically manipulated and imprinted quail chicks (C. coturnix japonica).

Bidirectional genetic selection of quail for early color preferences, for eighteen generations, resulted in nearly perfect choices of blue over red in one and red over blue in the other selected line. It also enhanced the preference of a grated over a dotted black-and-white pattern. Color and pattern preferences in hybrids of selected and control lines fell back to about halfway between parental values. Choices between composite stimuli of colors and patterns indicated summation of the respective, genetically influenced preference values, with partial dominance of color over pattern effects. Exposure to colors modified color choices. Exposure to colored patterns likewise modified color choices, but it did not change, or only marginally changed, choices between patterns. The phenotypic expression of this selective learning, however, was influenced by the genetically manipulated preference values and preference combinations of colors and patterns in the stimuli with which postexposure performances were tested. Overall, the data highlighted the need for concepts that would discriminate between the developmental and the episodic expression of genetic influences and genotype--environment interactions in behavior.

Animals↗
PubMedDate not supplied

A table of color distance scores for quantitative scoring of the Lanthony Desaturate color vision test.

The Lanthony Desaturate Panel D-15 (D-15d) color vision test is used in neurotoxicological testing to assess acquired color vision deficits. The original test design included a qualitative scoring method. Quantitative scoring requires mapping the colored objects used in the test into a color space describing perceptual distances. A table of these distances has previously been published for the saturated version of this color vision test, but not the desaturate test. This communication includes a table of color distances for the calculation of Bowman's Total Color Distance Score (TCDS) for the D-15d. This table should be useful for non-computerized scoring under field test conditions or for devising one's own computerized scoring methods using the tabulated color distances for a look-up table. Data analysis programs using SAS or Matlab are available from the author.

Color↗