T/CQAAS 009-2023 Active

Main Technical Content: 3. Terms and Definitions The following terms and definitions apply to this document. 3.1 Color Space A three-dimensional space used to represent colors. 3.2 Uniform Color Space A color space that can represent the same perceptual color differences at equal distances. 3.3 CIE 1976 (L*a*b*) Color Space A uniform color space recommended by CIE in 1976. This space is a three-dimensional rectangular coordinate system. 3.4 Color Difference A quantitative representation of color perception differences, denoted as E. 3.5 Luminance A visual property value that indicates the brightness of an object's surface color, graded on a scale from absolute white to absolute black. One of the three attributes of color. 3.6 Chroma A visual property value that indicates the intensity of an object's surface color, graded on a scale from white to black. One of the three attributes of color. 3.7 Hue (Hue) A characteristic of colors such as red, yellow, green, blue, and purple. One of the three attributes of color. 3.8 Psychological Luminance In a uniform color space, it corresponds to the indicator of luminance. In the L*a*b* color space, L* is defined as the CIE 1976 psychological luminance. 3.9 Psychological Chroma In a uniform color space, it represents the two coordinates within a surface of equal luminance. For example, the two coordinates a* and b* in the L*a*b* color space. 3.10 Standard Illuminant A specific spectral power distribution defined by CIE for incident on an object, including the standard illuminant D65 with an average daylight color temperature of approximately 6504K. 4 Principle The absorbance of the test sample in the wavelength range of 380nm-780nm is measured. The relative stimulus function and color-matching function are integrated, and then compared with the standard three-stimulus values to calculate the L* value, a* value, b* value, chroma C*ab value, and hue hab value of the sample. 5 Rea