Perceptual uniformity is the holy grail for color comparisons. A color space is perceptually uniform when a given numerical distance between two colors always corresponds to the same perceived visual difference — regardless of where in the space those colors sit.
The Problem with RGB
In RGB space, a Euclidean distance of 10 units between two dark blues looks like barely any change, while the same distance of 10 units between two yellows can appear dramatically different. This non-uniformity means that simple distance calculations in RGB are unreliable for human-perceived similarity.
CIELAB: The First Attempt
The CIE 1976 L*a*b* color space (CIELAB) was specifically designed to be perceptually uniform. It uses three axes: L* for lightness, a* for green–red, and b* for blue–yellow. While a significant improvement over RGB, CIELAB still has known non-uniformities, particularly in the blue region, which led to increasingly complex Delta E formulas (CIE76, CIE94, CIEDE2000) to compensate.
OKLAB: The Modern Solution
OKLAB, designed by Björn Ottosson in 2020, achieves better perceptual uniformity than CIELAB with a simpler mathematical model. Its cylindrical form, OKLCH (Lightness, Chroma, Hue), has been adopted by CSS Color Level 4, making it the de facto standard for perceptually uniform color manipulation on the web.
Why It Matters for Generative Art
In palette generation and color harmony, perceptual uniformity determines whether a gradient looks smooth or has banding, whether complementary colors feel equally vibrant, and whether a quantized palette faithfully represents the original image. Our Lab tools use OKLCH for gradient interpolation precisely because of this property.