Color Curves Node

Color Curves works like a LUT (Lookup Table) driven by splines. For each input value on a channel, the spline gives the output value. It is the most flexible tool for precise grading - you draw the correction you want.

It supports out-of-range values (pixels > 1.0 or < 0.0) in 32-bit float - important for HDR or linear work without clipping.

• Effects Library: Tools > Color > Color Curves
• Quick add: right-click in the Node Editor → Add Tool > Color > Color Curves

• Input (orange) - required. The 2D image to adjust.
• Effect Mask (blue) - optional. Limits the correction to an area.
• Reference Image (green) - optional. The reference image for automatic matching.
• Match Mask (white) - optional. A mask that defines the area used for matching (more flexible than the rectangle).

MediaIn → Color Curves → Merge 2D → Saver

Often used after a Color Corrector that sets the overall tone, for fine corrections by tonal range.

The Color Space menu at the top of the Inspector. It changes which channels are editable.

RGB (default)

Red, Green, Blue + Alpha. The most direct choice for adjusting colors.

YUV

Luma, Blue Chroma, Red Chroma. The analog PAL broadcast format. Lets you change brightness without touching the colors (Y alone) or the other way around.

HLS

Hue, Luminance, Saturation. Ideal for perceptual adjustments: shifting saturation without touching the values, or shifting the hue of the whole shot.

YIQ

Luma, In Phase, Quadrature. The NTSC broadcast format. Technical/legacy use.

CMY

Cyan, Magenta, Yellow. Useful when you think in print terms or for complementary adjustments.

The spline window shows a graph going from 0 in / 0 out at the bottom left to 1 in / 1 out at the top right. The initial diagonal line is the identity (no change).

• Click on the line = add a control point.
• Drag the point → changes the output value for the given input value.
• Raise the middle → brighter midtones.
• Lower the middle → darker midtones.
• Raise the left / lower the right = crush the extremes.

In/Out controls at the bottom: precise numeric values of the selected point.

Color Channels (R/G/B/A buttons): select which spline is active for editing. The labels change with the chosen color space (in HLS: H/L/S/A).

The Pick tool (eyedropper icon): samples colors from the image → automatically creates control points at the matching position on the spline.

White balance workflow in 3 steps:

1. With the eyedropper, select a pixel that should be neutral gray in the image (a white shirt in shadow, a sheet of paper, etc.).
2. Three points appear on the R/G/B splines at the pixel position (locked horizontally).
3. Adjust the Out of these points so they are all at 0.5 (perfect gray) → the shot is white balanced.

Picked points are locked horizontally (only the Out value can move). Right-click on a point → Unlock to release them.

Enable only the channels you need before picking - otherwise Fusion adds points on every spline, including the ones you do not want to touch.

Color Curves can automatically generate a LUT that matches a reference shot.

Match Reference

Adds control points that align the image with the reference (through the histogram). Connect the reference to the green input.

Sample Reference

Creates a LUT from the central scan line - useful to match a calibration image (color chart).

Number of Samples

Number of points generated. More = a precise match, but a risk of capturing noise.

Show Match Rectangle

Shows the sampled area in the viewer for debugging. Position adjustable with Center X/Y.

Pre-Divide / Post-Multiply

Avoids illegal additions on semi-transparent keyed edges.

S-curve (cinema contrast)

Two points: one in the shadows pulled down, one in the highlights pulled up. The curve takes an S shape. Boosted contrast without hard clipping. The most common grade for adding "punch".

Shadows (input ~0.25) → out ~0.15  (darker)
Highlights (input ~0.75) → out ~0.85 (brighter)

Lift shadows (matte cinema look)

Bottom-left point pulled up. Raised black point → less dense shadows, a "filmic" look.

Crush highlights

Top-right point pulled down. Lowered white point → compressed highlights. Useful for HDR → SDR.

Per-channel color shift

Select the Red channel, lower the shadows (input 0.3, out 0.2) → less red in the shadows = shadows tinted toward cyan. The classic teal & orange look.

• Fine grading - after a Color Corrector that sets the tone, a Color Curves refines by range. More precise than a second Color Corrector.
• Precise white balance - eyedropper on a neutral gray, then set the Out values to 0.5.
• Matching multi-camera shots - reference shot on green, Match Reference → an automatic LUT.
• HDR → SDR compression - crush the highlights with the master RGB curve.
• Calibration from a color chart - Sample Reference on the central line of the chart, Fusion learns the corrections per color patch.
• Film look through non-linear contrast - a custom S-curve with a slight white crush and a black lift simulates a good 35mm negative.

• Splines = smooth curves by default - for a hard cut, right-click on a point → Linear gives an abrupt change.
• Enable only the needed channels before using the eyedropper → otherwise you get unexpected points on channels you did not want to touch.
• Extra precision through the Spline Editor - the splines can also be edited in Fusion's global Spline Editor for very precise control (with tangents, velocities, etc.).
• Locked points - points picked with the eyedropper are locked horizontally to prevent accidental drags. Right-click → Unlock to release them.
• On a 32-bit float image, the splines can go beyond [0, 1] (out-of-range). It does not clip automatically - useful for HDR.
• For non-destructive grading, use Blend at 50% to dial in the correction (makes it easy to go back).
• Animation - the "Animated" mode allows curves that evolve over time (different from standard parameter animation).