The Physics and Perception of Color
Color is where physics meets perception. Light carries wavelengths, but color lives in the brain. These ten explorations trace the full arc of color science—from the CIE’s mathematical framework that maps human vision, through the opponent channels that wire our retinas, to the practical systems we use to name, measure, and reproduce color across displays, print, and paint. Drag, click, and explore how we see.
The mathematical foundation of color measurement, built from experiments on human observers in the 1920s–1930s.
The iconic horseshoe diagram mapping all visible colors to xy coordinates. Hover to read chromaticity values, click to place markers, and see the sRGB triangle.
The x̄, ȳ, z̄ spectral sensitivity curves that define the CIE Standard Observer. Compare the 1931 (2°) and 1964 (10°) versions, and trace individual wavelengths.
Toggle sRGB, Adobe RGB, Display P3, Rec. 2020, ProPhoto, NTSC, and CMYK gamut triangles on the chromaticity diagram. See how much of visible color each standard covers.
From cone cells to neural processing—the biology behind color perception and its limits.
Watch L, M, and S cone responses transform into Red–Green, Blue–Yellow, and Light–Dark opponent channels. Slide through the spectrum to see how your brain encodes color.
Two surfaces with completely different reflectance spectra can look identical under daylight but diverge under tungsten. Switch illuminants and watch metameric pairs match and mismatch.
See the world through protanopic, deuteranopic, tritanopic, and achromatic eyes. Compare Ishihara plates, spectra, nature scenes, and traffic signals side by side.
Regions of just-noticeable difference mapped across the chromaticity diagram. Explore why green is the hardest color to discriminate and blue the easiest. Scale from 1 to 7 SDCM steps.
Different ways to organize, name, and navigate the world of color—from blackbody physics to perceptual uniformity.
Slide from 1000K candlelight to 20000K blue sky along the Planckian locus. See standard illuminants (A, D50, D65, D75) and how blackbody radiation maps to color.
Explore the hue wheel, saturation–lightness square, and compare HSL’s double cone with HSV’s single cone. Drag the wheel and square to pick colors intuitively.
A perceptually uniform color notation using Hue, Value, and Chroma. Explore the color wheel, hue pages, and the 3D color tree—where equal steps look equally different.