Curves
Also known as: tone curve, curve adjustment
The grading control that maps input brightness to output brightness, the most precise way to shape contrast without moving the whole image equally.
Updated
What it means
A curve is a graph. Input values run along one axis, output along the other, and dragging the line changes how brightness is redistributed. Nothing else in a grade is this direct.
Its advantage over a contrast slider is locality. Lifting the shadows while leaving the highlights alone is one control point, where a Contrast adjustment would move everything at once.
Colour curves do the same per channel. A red curve lifted in the shadows warms the dark areas only, which is how a Color cast gets corrected where it actually lives, instead of tinting the entire frame to fix one part of it.
How it works in practice
The classic shape is a gentle S. Shadows pulled slightly down, highlights slightly up, which adds contrast while leaving the midtones where they were. Two control points do most of the work.
The Black point is set first, at the bottom of the curve, before anything else is shaped. Everything above it depends on where the floor sits, so shaping before that is wasted effort.
Scopes guide the hand. A Waveform shows exactly which part of the curve a shadow occupies, and that is more reliable than dragging until a clip looks right.
What to watch out for
Aggressive curves band. Stretching a narrow range of values hard produces Color banding in skies and gradients, and an 8-bit source shows it long before a 10-bit color one does.
Steep sections destroy detail. A nearly vertical part of the curve compresses everything above and below it, so highlights clip and shadows crush without anything looking wrong in a thumbnail. The damage shows up on a large screen.
Per-clip curves break matching. Twelve clips each shaped by eye produce twelve looks, which is why the per-clip work is correction and the shared look comes afterwards, applied once across everything.
How RawClip handles it
Tonal adjustment is applied consistently across the assembled sequence rather than negotiated clip by clip, so shots that sit side by side keep the same contrast. Source material with more colour depth tolerates that step better than a heavily compressed file.