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Colorimeter

About: Colorimeter is a research topic. Over the lifetime, 872 publications have been published within this topic receiving 12157 citations.


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TL;DR: This paper shall describe a method for the quantitative determination of both direct and indirect bilirubin in serum, in which protein precipitation and consequent loss of bilirubs have been eliminated and a quantitative study of the behavior of the direct, reaction has been made possible.

1,670 citations

Journal ArticleDOI
TL;DR: This study evaluated and compared the ability of a new computerized colorimeter and a simple visual test to match ceramic shade guide teeth and demonstrated 100% repeatability and fair repeatability.
Abstract: Statement of problem. Visual color matching to determine shades in dentistry is inconsistent and unreliable. If accurate, instrumental measurement of tooth color would provide objective, quantified data to match natural teeth to clinical shade guides. Purpose. This study evaluated and compared the ability of a new computerized colorimeter and a simple visual test to match ceramic shade guide teeth. Material and methods. Thirty-one (n = 31) observers with normal color vision were allowed unlimited time to match one set of Vita Lumin shade guide teeth to the corresponding shade guide teeth of a second Vita Lumin shade guide. The same test was administered to 14 of the observers several months later to determine within-subject variability. A computerized colorimeter (Colortron II) equipped with a positioning guide was used to measure the middle third of each shade guide tooth. Through a "match tool" present in the computer's software, readings from one shade guide were matched with readings of the other shade guide by using CIELAB measurements and ΔE values. The mean number of correct matches by the colorimeter and of correct matches in visual test were compared with a 1-tailed t test. Repeatability for both tests was determined with a paired t test. Results. The Colortron II instrument correctly matched 8 of the 16 tabs (50% correct), whereas visual matching by examiners averaged 7.7 of 16 correct matches (48% correct) (standard deviation 2.7). No statistically significant differences existed between the 2 methods. The colorimeter demonstrated 100% repeatability and the visual test demonstrated fair repeatability (correlation coefficient r=.60). Conclusions. Shade determination by visual means was inconsistent. Accuracy of a new colorimeter in matching porcelain shade guide teeth was only slightly better. (J Prosthet Dent 1998;80:642-8.)

358 citations

Journal ArticleDOI
TL;DR: A fiber-optics colorimeter based on the principle of volume reflection that is visually matched by subtractive adjustment of the illuminating color in one box, whereas the other box showed the central part of the tooth diffusely illuminated by illuminant C light is tested.
Abstract: Tooth color is caused by volume reflection, that is, passage of incident light through the tooth followed by backward emergence. This passage is concurrent with sideward displacement of photons that, in effect, influences the result of usual instrumental methods of determining tooth color. This problem is overcome by the use of large-field illumination and small-field observation. A fiber-optics colorimeter based on this principle is described. The color observed through two holes in a double box was visually matched by subtractive adjustment of the illuminating color in one box, whereas the other box showed the central part of the tooth diffusely illuminated by illuminant C light. This colorimeter was tested on wet, extracted human incisors in the tooth arch of a phantom-head. Results were compared with a visual standard-strip method described previously and with a conventional spectrophotometer. It was concluded that the fiber-optics colorimeter is a promising instrument, although technical improvement is necessary.

308 citations

Journal ArticleDOI
TL;DR: Though color may not supply important taxonomic distinctions among plants in a group as presently known, it may assume greater importance as new taxa are discovered and the method detailed here facilitates reference to the closest color chip in the Royal Horticultural Society Colour Chart.
Abstract: Communicating perceptions of color entails not only evaluation and description of colors by one individual but also the visualization by another of the colors described. Color charts have long played a unique intermediary role in this process. Visual color evaluation, however, is often flawed. The increased availability of portable color-measuring instruments now makes possible a more objective notation of specimen colors, and the method detailed here facilitates reference to the closest color chip in the Royal Horticultural Society Colour Chart. After surveying many color charts used by biologists for biological descriptions, Tucker et al. (1991) recommended using the Royal Horticultural Society (RHS) chart. They observe that the RHS chart was designed for horticultural taxa. (It does not, for example, sample extensively the color range of fungi.) I also recommend the RHS chart, but stress that color-evaluation technique is an essential and critical-though often neglected– aspect of color description. Careful color evaluation is desirable for botanical and horticultural descriptions. It is true that botanical descriptions commonly have not included detailed color references because, inter alia, color is not well preserved in most herbarium specimens. Some botanical exploration is, however, devoted to the search for plants with superior horticultural characteristics, including color. Moreover, though color may not supply important taxonomic distinctions among plants in a group as presently known, it may assume greater importance as new taxa are discovered. Both evaluating color and determining

260 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202339
202263
202119
202016
201925
201823