Betekenis en doel
5.1 De originele CIE-kleurenschaal gebaseerd op de drie stimuluswaarden X, Y, Z and chromaticity coordinates x, y is not visually uniform. Each subsequent color scale based on CIE values applies a weighting factor to provide a degree of uniformity so that the color differences across regions of the color space will be more comparable. Aan de andere kant, it is unlikely that the same color differences obtained for the same samples evaluated in different color scale systems. Om verwarring te voorkomen, comparisons should be made only when color differences or associated tolerances between samples are obtained for the same color scale system. For all colors of the specimen, there is no simple factor that can be used to precisely convert the color difference or color tolerance in one system into units of difference or tolerance in another system.

5.2 Color Difference E00 in Δ is highly recommended to use units (6) E* blood group units in the range of 0.0 to 5.0Δ. This color difference equation is applicable and widely used in industrial and commercial applications, including but not limited to automotive, coatings, cosmetica, inkten, verpakking, verven, kunststoffen, afdrukken, security and textiles.

5.3 Users of the color tolerance equation have found the addition of the three vector color difference components into a single scalar value in each system to be very useful in determining whether the sample color is within the tolerance specified by the standard. Echter, in order to control for color in production, het kan nodig zijn om niet alleen de omvang van de afwijking van de standaard te weten, maar ook de richting van deze afwijking. Information about the direction of small color differences can be included by listing the components determined by the three instruments for color differences.

5.4 Color tolerance selection based on instrument values should be carefully related to a visual assessment of the acceptability of hue, helderheids- en verzadigingsverschillen verkregen met praktijk D1729. De drie hier gepresenteerde tolerantievergelijkingen zijn uitgebreid getoetst aan dergelijke gegevens voor textiel en kunststoffen, en er is aangetoond dat ze consistent zijn met visuele beoordelingen, within the experimental uncertainty of visual judgments. This means that the equation itself misclassifies color differences whose frequencies are no greater than those of very experienced visual color matchers.

5.5 Although color difference and color tolerance equations are commonly applied to a variety of light sources, ze zijn afgeleid of geoptimaliseerd, of allebei, for daylight illumination. A good correlation with visual judgment may not be obtained when calculations are performed using other light sources. The use of tolerance equations in conditions other than daylight conditions requires visual confirmation of homochromic levels according to practice D4086.

ASTM 2244-2022 “Berekening van toegestane kleurlimieten en kleurverschillen met behulp van instrumentele kleurcoördinaten”

Reikwijdte van
1.1 This practice includes the calculation of color tolerances and small color differences between opaque specimens, such as painted panels, plastic pleisters of textielmonsters, based on color coordinates measured by an instrument based on daylight illumination. Practice D4086 should be used to verify instrumental results if it is suspected that specimens may be metamorphic, dat is, have different spectral curves despite visually similar colors. The tolerances and differences determined by these procedures are expressed in CIE 1976 CIELAB manual color space (1), 2 CMC tolerance units (2), CIE94 tolerance units (3), DIN99o color difference formula given in DIN 6176 (4), or approximately uniform visual color vision in CIEDE2000 color difference units (5).

1.2 For the Product specifications, the Buyer and the Seller shall agree on the allowable color tolerance between the specimen and the reference and the procedure for calculating the color tolerance. Specific color tolerances may be required for each material and use condition, as other appearance factors (bijv., sample proximity, glans, en textuur) may affect the correlation between the size of the measured color difference and its commercial acceptability.

1.3 Deze norm is niet bedoeld om alle veiligheidsproblemen aan te pakken, indien aanwezig, die verband houden met het gebruik ervan. Het is de verantwoordelijkheid van de gebruiker van deze norm om de juiste veiligheid te garanderen, gezondheids- en milieupraktijken en om vóór gebruik de toepasbaarheid van wettelijke beperkingen vast te stellen.

1.4 Deze internationale norm is ontwikkeld in overeenstemming met de internationaal erkende standaardisatieprincipes die zijn vastgelegd in het Besluit over de beginselen voor de ontwikkeling van internationale normen, Richtlijnen en aanbevelingen uitgegeven door het Comité voor technische handelsbelemmeringen van de Wereldhandelsorganisatie.