Light · surfaces · color
Color solid
Explore which colors a surface could reflect under daylight. The uneven edge comes from the interaction of light, surface reflectance, and human color sensitivity.
Drag to orbit · scroll or pinch to zoom · pick a color
The edge is a limit on reflected light
Light supplies the energy
A passive surface can reflect between 0% and 100% of the light arriving at each wavelength. This solid explores all those possibilities under D65 daylight.
Selectivity creates color
Strong color needs unequal reflection across the spectrum. Approaching perfect white requires reflecting nearly everything; approaching black leaves almost no light. Both ends converge on gray.
The screen has its own limit
The dashed outline marks sRGB at the same lightness and hue. Many possible surface colors lie beyond it. Their swatches are screen approximations; their positions stay where the calculation puts them.
New coordinates: height is CIELAB lightness L* (0–100), distance from gray is chroma C*ab, and angle is hue hab. These are not Munsell value/chroma or software HSV. Chroma has no universal “100%” endpoint.
Physical assumptions, calculation, and sources
This is a numerical object-color solid for ideal, nonfluorescent reflecting surfaces, under CIE D65 illumination and the CIE 1931 2° standard observer. It is a theoretical upper bound, not a promise that a pigment exists at every point. Emissive colors, fluorescence, gloss, changing illumination, individual observers, and surrounding colors are outside this calculation.
The calculation combines the illuminant spectrum, surface reflectance, and color-matching functions to obtain CIE XYZ. Reflectance can vary independently between 0 and 1 at each 1 nm sample from 360–830 nm. All supporting planes of this bounded spectral sum determine its boundary; no restriction to two-transition spectra is imposed. The result is converted to CIELAB relative to the illuminant white.
The page samples the boundary every 10° of hue and 5 units of L*. Connecting lines are visual interpolation, not additional calculated boundary points. At L* 0 and 100 the theoretical solid closes at neutral black and white. Each of the 684 calculated boundary positions is independently checked for a feasible reflectance spectrum; stepping 0.05 C* farther out must fail that check. Finite wavelength sampling and a standard observer remain approximations to reality.
The solid's interior dots and hue-page chips use a common C* scale. Blank grid cells lie beyond the calculated surface boundary at that hue and lightness; the last column selects the boundary itself. They are no longer gaps in a historical collection. Selecting gray retains the chosen hue page, although gray itself has no hue.
Colors beyond sRGB are shown by reducing display chroma at the same L* and hue, with a small margin inside sRGB; their plotted coordinates are unchanged. The spectral D65 white is normalized to the specified sRGB D65 white for display. The dashed outline is the standard sRGB gamut, not a measurement of your screen. CIELAB is useful but imperfectly perceptual, especially at extreme chroma; the vertical drawing scale is stretched for legibility.
The CIE source tables and the transformed boundary data are provided under CC BY-SA 4.0. The source tables are unmodified; the boundary data are derived by the calculation described above.