Sat vs

The same curve tool, on saturation instead of hue.

Sat vs Sat changes saturation according to how saturated a color already is: drop the right end to tame only the loud colors, or lift the left end to bring up the dull ones without pushing what’s already vivid. Sat vs Lum brightens or darkens by saturation – darken the saturated colors and they look denser, like dye. Lum vs Sat sets saturation by brightness, to take color out of the highlights so they roll off clean, or keep it out of the deepest shadows.

Every curve opens flat with a point at each end; plus adds one in the middle. The eyedropper shows where a color from the photo sits on the axis, and the histogram shows where all of them fall – on most photos, the left half.