Color Mixing Calculator

Mixing two colors numerically means taking a weighted average of their channels, where the ratio t runs from 0 (all of color one) to 1 (all of color two). The RGB mode here interpolates the gamma-encoded sRGB values directly, which is arithmetically identical to alpha compositing a foreground over a background at opacity t, the operation every design tool performs when you drop a layer to 50 percent. The perceptual mode squares each channel before averaging and takes the square root afterwards, an approximation of blending in linear light with a gamma of 2.0. The difference is not subtle: mixing full red (255, 0, 0) with full green (0, 255, 0) gives a dull olive near (128, 128, 0) under naive averaging, but roughly (180, 180, 0) under the gamma-aware version, which is far closer to what two overlapping stage lights actually look like. The subtractive mode converts both inputs to CMYK, interpolates the four ink percentages, and converts back, imitating how stacked inks darken paper. None of the three modes is spectrally correct. Real pigments both absorb and scatter light with wavelength-dependent curves, so predicting a paint mixture properly requires two-constant Kubelka-Munk theory rather than channel arithmetic. The CMYK path is also a naive algebraic conversion with no ICC profile, no black generation strategy, and no total ink limit, where commercial sheetfed presses typically cap total area coverage near 300 percent and account for dot gain of 10 to 20 percent in the midtones.

The split between adding light and subtracting it was settled experimentally in the nineteenth century. Hermann Grassmann stated his laws of additive color mixture in 1853, establishing that light mixtures behave linearly, which is precisely the property that makes weighted averaging a valid model when the values are in linear light. James Clerk Maxwell demonstrated additive mixing with spinning colored discs in the 1850s and projected the first three-filter color photograph at the Royal Institution in 1861. On the subtractive side, Jacob Christoph Le Blon was printing multi-plate mezzotints in red, yellow and blue in London around 1719 to 1725, later adding a black plate, which is the direct ancestor of the four-ink CMYK process. Paul Kubelka and Franz Munk published their layer reflectance theory in 1931, and it remains the basis of industrial paint and textile matching. The gamma problem that the perceptual mode addresses arose from the digital side: sRGB was proposed by Hewlett-Packard and Microsoft in 1996 and standardized as IEC 61966-2-1 in 1999 with an encoding curve near 2.2, but almost all graphics software of that era blended directly on the encoded numbers, producing gradients between saturated complements that dipped visibly dark in the middle. The W3C answered in CSS Color Module Level 4 with the color-mix function, which lets an author name the interpolation space explicitly as srgb, oklab or lch; support landed across the major browser engines during 2023.