Weighting function for the measurement of lightness differences in gonioapparent and dark colors

Rodrigues, Allan B. J.; Locke, John

doi:10.1117/12.464603

Cited by 1 publication

(3 citation statements)

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“…p. 174, 175, and 225 of Ref. 2) . For example, tolerance in terms of dE CMC (2:1) increases from 0.79 at 110° to 1.32 at +15° aspecular angle according to some studies, and from 1.43 at 110° to 2.75 at 15° according to another .…”

Section: Improving the Process Of Setting Qc Color Tolerancesmentioning

confidence: 87%

“…Preliminary work by Rodrigues and Locke has shown that lightness tolerances of samples with a lightness close to L * = 150 are widened by a factor of 1.5 as compared to samples with L * = 100. Based on this research, a CIE94 difference equation with modified S L function was tentatively proposed, but obviously more work has to be done in this area . It is expected that such research will show that the tolerance will widen further for lightness values L * > 150.…”

Section: Improving the Process Of Setting Qc Color Tolerancesmentioning

confidence: 99%

“…Based on this research, a CIE94 difference equation with modified S L function was tentatively proposed, but obviously more work has to be done in this area. 57 It is expected that such research will show that the tolerance will widen further for lightness values L* [ 150.…”

Section: How To Account For Angular Variationmentioning

confidence: 99%

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Setting tolerances on color and texture for automotive coatings

Kirchner

Ravi²

2012

Color Research & Application

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In the automotive industry, color quality control is increasingly done by reflection measurements. We discuss how color tolerances are set in specifications to suppliers of add‐on parts and to paint suppliers. We mention several factors that often lead to unrealistically tight settings, and therefore to incorrect rejections and unnecessary high productions costs. We show that this is likely to occur when the dEab color difference equation is used, or when a strict criterion separating pass from fail is used instead of specifying a “grey area” where instrumental monitoring needs to be followed by visual assessments. Unrealistically, tight tolerances also result from halving tolerances in the supply‐customer chain in an attempt to compensate color variations due to uncontrolled application conditions. Tolerances should be widened further when a gap separates an add‐on part from the car body, making visual discrimination of color differences less critical. Other common situations where tolerances should be widened are the presence of visual texture in effect coatings, the lightness of metallic coatings becoming very high (L*> 100) and measurement geometries close to the gloss angle. Finally, we address the issue that instrumental color tolerances should not be tighter than what is allowed by instrumental reproducibility, repeatability, and inter‐instrument agreement. Accounting for these factors, we provide a set of reasonable values for tolerances on color and on visual texture parameters, based on our own practical experience. But realistic tolerance values depend very much on actual conditions, and should be agreed in tripartite discussions among automotive industry, suppliers of add‐on parts, and paint supplier. © 2012 Wiley Periodicals, Inc. Col Res Appl, 39, 88–98, 2014

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Section: Improving the Process Of Setting Qc Color Tolerancesmentioning

confidence: 87%

Section: Improving the Process Of Setting Qc Color Tolerancesmentioning

confidence: 99%