Diffusegray

Diffusegray is a term used in computer graphics and lighting to denote a neutral, non-specular gray color representing purely diffuse (Lambertian) reflection. It does not describe a physical pigment on its own but rather the way a surface reflects light evenly in all directions, independent of the viewing or lighting angle.

In rendering, diffuse gray is defined by the diffuse reflectance or albedo of a surface and is typically expressed as a grayscale value with equal RGB components (R = G = B). It serves as a baseline color for testing shading models and materials, and is commonly used in physically based rendering as part of the surface’s albedo. Because it is a diffuse property, the color remains constant under changes in light direction, unlike specular highlights.

Representation wise, diffuse gray can be described in linear or nonlinear color spaces. In the standard sRGB space, a gray color has equal channel values, such as 0.5 for mid-gray (in a 0–1 scale) or 128 out of 255 for 8-bit-per-channel color. When working in linear light, the numerical value corresponds to the material’s reflectance; gamma correction may alter the perceived brightness when displayed on typical monitors.

See also: diffuse reflection, Lambertian reflectance, albedo, grayscale, color spaces.