OKLab

OKLab is a perceptual color space designed to provide perceptual uniformity and a simple, device-independent representation of color. It was introduced as part of the OkLab color space family by Björn Ottosson, with the aim of enabling straightforward color interpolation and comparison across wide displays while remaining compatible with common color workflows.

The forward transformation typically starts from a color in a linear color space, such as linearized sRGB. The color is first mapped to a linear LMS cone response using a 3x3 matrix. Each component of the LMS response is then transformed by a nonlinear cube-root operation to reduce the nonlinearity of human vision. A second 3x3 matrix maps the cube-root LMS values to the OKLab coordinates, yielding L for lightness and a and b for chromatic information in a two-dimensional plane.

OKLCh is a cylindrical variant of OKLab that represents colors in terms of lightness L, chroma C, and hue h. This representation is often used for more intuitive color selection and for perceptual uniformity in circular color spaces.

Inverse transformations return a color from OKLab to conventional RGB. The process is inverted: OKLab to LMS via the inverse of the mapping matrix, then the cube is raised to recover the LMS components, followed by a reverse matrix to linear sRGB and the application of gamma correction to obtain standard sRGB values.

OKLab and its cylindrical variant are used in color tooling, design, and color science for tasks such as color difference measurement, interpolation, and perceptually uniform color selection across wide-gamut displays.