An illuminant is a mathematical representation of a theoretical real light source, used for calculating tristimulus values from a spectrophotometric measurement. The numbers represent relative power of the theoretical source at each point in the visible spectrum. The relative power distribution of a real source could be used for calculation, but real sources are difficult to standardize. What illuminants are available?
All of X-Rite's software and hardware can simulate the Main illuminant types:
Illuminant A: Mathematical representation of tungsten halogen (incandescent). Color temperature: 2856K. Can be used to test metamerism. Simulates typical home or store accent lighting.
Illuminant C: Mathematical representation of filtered tungsten halogen (daylight). Color Temperature: 6774K. Can be used to test metamerism. Simulates the CIE average daylight.
Illuminant D50: Mathematical representation of noon sky daylight. Color temperature: 5000K. Uses include general evaluation of color, metamerism testing, and evaluating color uniformity and quality in the graphic arts industry.
Illuminant D65: Mathematical representation of average north sky daylight. Color temperature: 6500K. Uses include general evaluation of color, metamerism testing, providing visual correlation with spectrophotometric instrumental readings, and conformance with European and Japanese standards. Simulates average north sky daylight.
Illuminant D75: Mathematical representation of north sky daylight. Color temperature: 7500K. Uses include general evaluation of color, metamerism testing, and visual evaluation of opaque materials as outlined by ASTM D1729. Simulates north sky daylight.
Illuminant F2 (CWF-2): Mathematical representation of commercial, wide band fluorescent used in the USA (Cool White Fluorescent). Color temperature: 4150K. Uses include metamerism testing. Simulates typical office or store lighting in the USA.
Illuminant F7 (DLF-7): Mathematical representation of commercial, wide band fluorescent used in the USA (Deluxe). Color temperature: 6500K. Uses include metamerism testing.
Illuminant F11 (NBF-11): Mathematical representation of commercial, narrow band fluorescent used in the USA. Color temperature: 4000K. Uses include metamerism testing. In USA equivalent to TL84.
Illuminant F12 (Illuminant U30): Mathematical representation of commercial, rare earth phosphor, narrow band fluorescent. Color temperature: 3000K. Can be used to test metamerism. Simulates typical store lighting for Sears (USA equivalent of TL83).