CIE Standard Illuminants

The CIE standard illuminants are artificial light sources defined by the CIE whose radiation closely approximates the CIE standard illuminants A, C, and D65.

Standard illuminants are light types standardized by the CIE, each defined by a specific spectrum. The choice of an illuminant is used in color measurement to represent the color impression of an object under a selected light source. Here are some of the most common standard illuminants:

• D65: This is a widely used daylight standard with a color temperature of approximately 6500 Kelvin. D65 simulates the light of an overcast day.
• D50: This standard illuminant has a color temperature of approximately 5000 Kelvin and is commonly used in the graphic and printing industries.
• A: This stands for “Incandescent” and describes light with a color temperature of about 2856 Kelvin.
• F: These standard illuminants refer to fluorescent light and are divided into various types that represent different color temperatures and light qualities (e.g., F7 – Industrial, F11 – Department Store, Warehouse, Office).
• C: This illuminant describes light with a color temperature of 6674 Kelvin and corresponds to daylight without UV components. Today, this illuminant is typically replaced by D65, except in some older standards.