An abridged technique to diagnose spectrophotometric errors

Berns, Roy S.; Reniff, Lisa

doi:10.1002/(sici)1520-6378(199702)22:1<51::aid-col8>3.0.co;2-3

Cited by 12 publications

(10 citation statements)

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“…The capability of an instrument to reproduce the specified standard values is a measure of its accuracy and is expressed as a deviation from an accepted reference level. Inaccurate measurements are primarily associated with the existence of systematic errors (bias) such as photometric scale errors, wavelength errors, stray light, bandwidth, polarization and geometrical errors (17, 18). Precision is the capability of an instrument to give the same results repeatedly and is divided into repeatability and reproducibility.…”

Section: Introductionmentioning

confidence: 99%

Precision of in vivo spectrophotometric colour evaluation of natural teeth

Karamouzos

Papadopoulos

Kolokithas

et al. 2007

J of Oral Rehabilitation

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The aim of the study was to evaluate the precision of a reflectance spectrophotometer during longitudinal assessment of tooth colour in vivo. The spectrophotometric data of five standardized circular areas on the labial surfaces of six teeth (four upper and two lower), from 22 dental students, were recorded on three separate days (1st, 3rd and 30th) employing a repeated-measuring design (n = 3). Total colour differences were calculated according to the equation DeltaEpsilon = [(DeltaL*)(2) + (Deltaa*)(2) + (Deltab*)(2)](1/2). It was found that all measured teeth areas, recorded by the same examiner (DeltaEpsilon(INTRA)), demonstrated minor colour changes during the three different time intervals, which did not exceed in every case the 50:50% perceptibility threshold of DeltaEpsilon = 1, thus indicating a good match. The smallest DeltaEpsilon values were recorded for the upper central incisors, whereas lower central incisors and upper first premolars revealed the most significant colour differences (0.68 +/- 0.21 and 0.70 +/- 0.25 DeltaEpsilon-units, respectively). The central zone of the middle third of each labial tooth surface exhibited the most precise recordings. With regard to interexaminer reproducibility (DeltaEpsilon(INTER)), the mesial and distal areas of all measured teeth presented the most statistically significant colour differences (0.48 +/- 0.15 and 0.50 +/- 0.17 DeltaEpsilon-units, respectively). It is concluded that the spectrophotometer tested in the present study can provide a precise measurement of tooth colour in vivo. However, in rejection of the null hypothesis, the type (posterior teeth, mandibular incisors) and the mesial and distal areas of natural teeth affected the repeatability and reproducibility of intraoral spectrophotometric measurements.

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Section: Introductionmentioning

confidence: 99%

Precision of in vivo spectrophotometric colour evaluation of natural teeth

Karamouzos

Papadopoulos

Kolokithas

et al. 2007

J of Oral Rehabilitation

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“…For example, the optical parameters or parts such as optical geometry (45 /0 for HIS, d/8 for D650) and spectral component (grating for HIS, integrated sphere for D650) for HIS and D650 are different. In order to improve the interinstrumental agreement for color measurement, a series of regression models 18,19 were developed to overcome the systemic error of instrument itself. The R-Model was developed by Chung et al 20 to improve the interinstrumental agreement, which was based on the correction of the reflectance values within the visual spectrum(400-700 nm).…”

Section: Interinstrumental Agreement Between His and D650mentioning

confidence: 99%

Color measurement of single yarn based on hyperspectral imaging system

Zhang

et al. 2020

Color Research & Application

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This article proposed a novel approach to color measurement of a single yarn using hyperspectral imaging system (HIS). Due to the size of a single yarn, it is impossible for spectrophotometers to measure its color directly. The HIS can acquire the spectral reflectance of continuous bands within a region of interest on a yarn sample, which can achieve color measurement of a single yarn compared with traditional spectrophotometers. A single yarn is segmented from the background by a spectral matching method through adaptively setting threshold of Fréchet distance values. The spectral reflectance of single yarn is specified by a method that lightness of pixels used as weight. The experiment based on Pantone Cotton Chip Set shows that the interinstrument agreement between the HIS and a standard spectrophotometer Datacolor SF650 has a significant improvement after using the R‐Model, and the average percentage improvement of the color difference is up to 54.99%. The yarn segmentation comparative experimental results show that the proposed method to segment single yarn from background is better in retaining the edge information of the yarn than the modified K‐means clustering method, and the color of the yarn segmented by the proposed method is more similar to the actual color of single yarn.

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“…Moreover, the integrating sphere must contain the light shields to prevent the light going directly from the light source (or from the integrating sphere) to the detector. When measuring the reflectance color of a sample, several effects could introduce errors into the results and should be corrected acceptably [4,9,22,23]. The presence of specularly reflected light on the sample, the fluorescence in the sample and the metallic or pearlescent sample structure are some examples of sources of possible errors of an illumination configuration.…”

Section: Basic Illumination and Instrumental Lightreflectance Colorimmentioning

confidence: 99%