D65

D65 is a standard illuminant defined by the International Commission on Illumination (CIE) that models average daylight. It corresponds to a correlated color temperature of about 6500 kelvin and is widely used as a reference white point in colorimetric calculations and color management.

The spectral power distribution (SPD) of D65 is a standardized representation of daylight, not a simple blackbody spectrum. The SPD is published by the CIE and used to compute tristimulus values and color coordinates under D65. On the CIE 1931 chromaticity diagram, the white point for D65 is commonly specified as x = 0.3127 and y = 0.3290.

Applications of D65 include its use as the white point for many color spaces and imaging workflows, such as sRGB and Rec. 709. It serves as a reference in ICC profiles, camera and display calibration, color matching in printing and digital imaging, and white-balancing procedures in photography and video to simulate noon daylight conditions.

D65 is part of the D-series of standard illuminants, which model daylight under different conditions. D50, for example, is used in the printing and graphic-arts industry, while D65 is often favored for evaluating color under typical daylight. The choice of illuminant affects color appearance in devices and media, so D65 provides a common, widely accepted baseline for color science and interoperability.

Notes and availability: The exact SPD, tristimulus values, and chromaticity coordinates for D65 are specified in CIE publications and ISO standards and are used across measurement instruments and software tools for consistent color reproduction.