UNLIMITED FREE ACCESS TO THE WORLD'S BEST IDEAS

close
Already an Engineering360 user? Log in.

This is embarrasing...

An error occurred while processing the form. Please try again in a few minutes.

Customize Your Engineering360 Experience

close
Privacy Policy

This is embarrasing...

An error occurred while processing the form. Please try again in a few minutes.

AATCC 173

Test Method for Calculation of Small Color Differences for Acceptability

active, Most Current
Buy Now
Organization: AATCC
Publication Date: 1 January 2015
Status: active
Page Count: 4
scope:

Purpose and Scope

The CMC formula is a modification of the corresponding CIELAB color-difference formula. It has colordifference symbol ΔEcmc. Even though use of the CIE 1976 L*a*b* (CIELAB) equation provides industry with a 'standard' means of calculating and communicating color differences of trials from their standards (see 8.1), it is recognized that CIELAB color-difference values (ΔE*) correlate poorly with visual assessments. The lack of correlation is caused by the non-uniformity of CIELAB color space (see Fig. 1). Significantly improved correlation between visual assessments and instrumentally measured color differences is given by the CMC colordifference formula (see 7.1 to 7.3). The improvement in correlation between visual and instrumental color-difference reports yielded by the CMC equation will usually permit the adoption of a single- number tolerance for judging the acceptability of a color match in most situations, regardless of both the color of the standard and the direction of the color difference of any trial from it. Another equation, CIE94 has been considered, but it has not shown any significant improvement over CMC (see 8.2).

The CMC formula retains, in modified form, the partitioning of overall color difference into differences in lightness, chroma, and hue components (see Fig. 2) which is present in the CIELAB color-difference formula. Using the ellipsoidal semi-axes (SL, cSC, and SH) makes the CMC equation suitable for a wide range of uses.

Document History

AATCC 173
January 1, 2015
Test Method for Calculation of Small Color Differences for Acceptability
Purpose and Scope The CMC formula is a modification of the corresponding CIELAB color-difference formula. It has colordifference symbol ΔEcmc. Even though use of the CIE 1976 L*a*b* (CIELAB)...
January 1, 2015
CMC: Calculation of Small Color Differences for Acceptability
Purpose and Scope The CMC formula is a modification of the corresponding CIELAB color-difference formula. It has colordifference symbol ΔEcmc. Even though use of the CIE 1976 L*a*b* (CIELAB)...
January 1, 2009
CMC: Calculation of Small Color Differences for Acceptability
Purpose and Scope The CMC (ℓ:c) formula is a modification of the corresponding CIELAB color-difference formula. It has color-difference symbol ∆Ecmc. Even though use of the CIE 1976 L*a*b* (CIELAB)...
173
January 1, 2005
CMC: Calculation of Small Color Differences for Acceptability
Purpose and Scope The CMC (ℓ:c) formula is a modification of the corresponding CIELAB color-difference formula. It has color-difference symbol ∆Ecmc. Even though use of the CIE 1976 L*a*b* (CIELAB)...
173
January 1, 1998
CMC: Calculation of Small Color Differences for Acceptability
A description is not available for this item.
173
January 1, 1992
CMC: Calculation of Small Color Differences for Acceptability
A description is not available for this item.

References

Advertisement