CRI is the abbreviation of color-rendering index, which is "color rendering index" in Chinese and is a general term.
Ra is the symbol of "general color rendering index", which is the average of the first 8 color rendering indexes among the 15 color rendering indexes.
The color rendering index CRI has 15 colors and 15 color names: R1, light gray-red; R2, dark gray-yellow; R3: saturated yellow-green; R4, medium yellow-green; R5, light blue-green; R6, light blue; R7, lavender blue; R8, lavender purple; R9, saturated red; R10, saturated yellow; R11, saturated green; R12, saturated blue; R13, Caucasian skin color; R14, leaf green; R15, yellow person color.
The color rendering index Ra we usually talk about refers to the average color rendering index of the first 8 color samples, and R9-R15 is the special color rendering index.
RA takes the average color rendering index of the first eight common colors, recorded as Ra, to characterize the color rendering of this light source.
