Hue rotation (hue shift)

Hue rotation moves every color in a design the same number of degrees around the color wheel while leaving lightness and chroma alone. A blue-and-orange scheme rotated 120 degrees becomes red-and-green: the angular relationships (complementary, analogous) survive intact and only the mood changes. Contrast is a looser promise. Even with OKLCH lightness and chroma held fixed, the measured WCAG ratio between two swatches moves as the hue moves, and gamut mapping a rotated color back into sRGB shifts it further, so remeasure rather than assume.

It is the fastest way to generate palette variants, seasonal skins, or colorways from one approved scheme, and the fastest way to recolor an illustration without repainting it. The dials are everywhere: the Hue slider in Photoshop's Hue/Saturation, the H channel in HSL, the h value in OKLCH, and the CSS filter hue-rotate(90deg).

Two gotchas. The CSS filter is a fake. hue-rotate() is a fixed matrix multiply on sRGB values, not a real rotation, so it drifts lightness and desaturates on the way around; rotating the h channel in OKLCH is the honest version. And equal degrees are not equal perceptual steps: hues bunch up in the greens and stretch out in the blues, and a 30 degree spin near yellow changes apparent brightness far more than the same spin near cyan. Always eyeball the result instead of trusting the number.