Color Grading Curves: Luma vs RGB S-Curve and Hue vs Sat Sky

Curves on a landscape: the same S-curve on RGB and on Luma shows how RGB adds saturation, then Hue vs Sat and Hue vs Luma deepen the sky, Hue vs Hue turns the foliage greener, and Luma vs Sat quiets the shadows, with the scopes responding.

Color grading tutorial · chapter 5 Curves in Color Grading Shape contrast with RGB and luma curves, fix or create casts with channel curves, and change single colours with the hue curves and HSL. Read the chapter →

Key moments

1. 1 RGB vs Luma S-curve , starts at 0:00
2. 2 A deeper sky , starts at 0:16
3. 3 Foliage and shadows , starts at 0:29
4. 4 Try it yourself , starts at 0:43

Transcript

RGB vs Luma S-curve 0:00

1. 0:01 The Custom curve starts as a straight diagonal: every input level comes out unchanged.
2. 0:02 An S-curve on RGB adds contrast, and the vectorscope trace grows: the colours get louder too.
3. 0:09 The same S-curve on Luma spreads the waveform just as much, but the vectorscope barely moves.

A deeper sky 0:16

1. 0:16 Hue vs Sat raised at the sky’s blue stretches only the blue part of the vectorscope trace.
2. 0:22 Hue vs Luma lowers the same blue slightly, so the sky reads deeper on the waveform, not just more saturated.

Foliage and shadows 0:29

1. 0:29 Hue vs Hue turns the yellowish greens a few degrees towards green, leaving the sky alone.
2. 0:35 Luma vs Sat calms colour in the deepest shadows, a finishing touch that also hides colour noise.
3. 0:40 The split compares the original landscape with the curves grade.