A perceptually uniform color space, or just "uniform color space"—sometimes called a *color appearance model*. As Rune Madsen notes: > On the surface, perceptual uniformity is somewhat easy to explain: These color spaces are human-friendly alternatives to color spaces such as sRGB, and they are incredibly helpful for designers working in code. ## CAM vs UCS A color appearance model (CAM) is a mathematical model that tries to describe human color vision *perceptually*, rather than with physics. A uniform color space (UCS) ## Specific Spaces There are a lot of different models. This is my best attempt to group them, although I am likely getting some of the hierarchy wrong: * CIELUV * HSLUV (cylindrical transformation) * CIELAB * [[LCH and OKLCH (color space)#LAB/LCH and OKLAB/OKLCH|LAB/OKLAB]] (implementation of CIELAB with cartesian a/b coordinates) * [[LCH and OKLCH (color space)|LCH/OKLCH]] (cylindrical transformation of CIELAB polar coordinates) * CAM02 * CAM16 ![[SebestaBryan_ColorModelSpaceMethod_Tree_zoomIntoCAMs.png]] ## Reference [Wikipedia. "Color appearance model" (accessed June 2024).](https://en.wikipedia.org/wiki/Color_appearance_model) See also [HCL color space](https://en.wikipedia.org/wiki/HCL_color_space). [Baldwin, Nate. "Color appearance model (Uniform color space)" (Color & Contrast, accessed June 2024).](https://colorandcontrast.com/#/color-appearance-model) [Madsen, Rune. "Perceptually uniform color spaces" (Programming Design Systems, accessed June 2024).](https://programmingdesignsystems.com/color/perceptually-uniform-color-spaces/index.html) ### Conversation [Verou, Lea. "On compliance vs readaibility: generating text colors with CSS" (May 2024, personal site).](https://lea.verou.me/blog/2024/contrast-color/) Lea is awesome. This is where she notes that the OKLCh color is "the most perceptually uniform polar color space" that the web supports. [Lilley, Chris. "What are color gamuts" (July 2023, personal blog).](https://svgees.us/blog/whatGamuts.html) See the section "The OKLab (LKLCH) color space" halfway down. [Vidra, Vojtěch and Pešička, Ondřej. "LCH is the best color space!" (December 2022, Atmos blog).](https://atmos.style/blog/lch-color-space) [Sitnik, Andrey and Turner, Travis. "OKLCH in CSS: why we moved from RGB and HSL" (October 2022, Evil Martians blog).](https://evilmartians.com/chronicles/oklch-in-css-why-quit-rgb-hsl) A good explainer of oklch's benefits over HSL, HSV, lch, and lab, looking forward to CSS Color 5. See also [their color picker](https://evilmartians.com/opensource/oklch-color-picker). [Ottoson, Björn. "A perceptual color space for image processing" (December 2020, personal blog)](https://bottosson.github.io/posts/oklab/) Björn created the oklab color space, and here he outlines why and how. He also notes the deficiencies of CAM02 and CAM16. I love this line: "It is called the Oklab color space, because it is an OK Lab color space." [Verou, Lea. "LCH colors in CSS: what, why, and how?" (April 2020, personal site).](https://lea.verou.me/blog/2020/04/lch-colors-in-css-what-why-and-how/) [Koopersmith, Daryl and Wilson, Miner. "Designing accessible color systems" (October 2019, Stripe blog).](https://stripe.com/blog/accessible-color-systems) Discusses how they approached using CIELAB. See also [this lch color picker](https://huetone.ardov.me/) based on the Stripe tool.