Accuracy of approximations for CIELAB chroma and hue difference computation
✍ Scribed by Peter D. Burns
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 89 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0361-2317
No coin nor oath required. For personal study only.
✦ Synopsis
The transformation in CIELAB from differences where h ab is the hue angle of the reference color. Equation (1) rotates the differences 2 in Da* and Db* by the angle in the L*, a*, b* coordinates to those in lightness, 0h ab . The rotated differences are taken as equal to chroma, and hue, DL*, DC * ab , DH * ab , can be approxi-DC* ab and DH* ab , respectively. mated by a rotation in 3-space. Expressions for the error This simple matrix form lends itself readily to the analin the approximation of chroma and hue differences are ysis of error propagation between the two CIELAB repredeveloped. Significant errors are introduced if either the sentations. 3 From multivariate statistics given a set of hue angle or chroma difference between reference and signals, DL*, Da*, Db*, with error described by the sample colors are large. A computed example illustrates covariance matrix, S DL *Da *Db * , the equivalent covariance the use of the analysis.