GB/T 7921-2008 in English

《GB/T 7921-2008均匀色空间和色差公式》由TC120（全国颜色标准化技术委员会）归口，主管部门为国家标准化管理委员会。
本标准规定了在视觉上近似均匀的CIE1976（L*a*b*）色空间和CIE1976（L*u*v* ）色空间以及相应的色差公式和CIEDE2000色差公式的计算方法。
本标准适用于物体色和光源色的表示以及色差的表示和计算。

1 Scope

This standard specifies CIE 1976(L*a*b*) color space and CIE 1976(L*u*v*) color space which are visually approximately even and the calculation methods for the corresponding color difference formula and CIE DE 2000 color difference formula.

This standard is applicable to the expression of object color and light source color as well as the expression and calculation of color difference.

2 Normative References

The following standards contain provisions which, through reference in this text, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, the parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards. For undated references, the latest edition of the normative document referred to applies.

GB/T 5698 Glossary of Color Terms
CIE 101: 1993 Parametric Effects in Colour Difference Evaluation
CIE 142: 2001 Improvement to Industrial Color Difference Evaluation

3 Terms and Definitions

For the purposes of this standard, the terms and definitions specified in GB/T 5698 and those listed below apply.

3.1

CIE 1976 lightness

coordinate in CIE 1976 uniform color space representing object color lightness, its symbol is L*

Foreword i
1 Scope
2 Normative References
3 Terms and Definitions
4 CIE 1976 UCS Diagram
5 CIE 1976 Uniform Color Spaces and Color Difference Formula
6 CIEDE2000 Color Difference Formula
Annex A (Informative) Precautions for CIE 1976 Uniform Color Space Calculation and Application