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Curves

Node icon
Color

Fine-tune tonality with spline curve adjustments per channel. The most precise tonal control available.

Curves provides per-channel tonal adjustment using a monotone cubic spline. Each point on the curve maps an input brightness to an output brightness. The Master channel affects all RGB channels; individual R, G, B channels adjust colors independently.

Curves gives you more precise control than Levels because you can target specific tonal ranges (like just the quarter-tones or three-quarter-tones) that Levels can’t address.

Parameters

Section titled “Parameters”

Pins

ImageImage
InputRequired
MaskMask
InputOptional
ImageImage
Output

Color

ChannelChoice
Default: Master

Which curve to edit

  • MasterAdjust all RGB channels together with a single curve.
  • R
  • G
  • B
Master CurveData
Default: [[0.0,0.0],[255.0,255.0]]

Master tone curve (control points). Default = identity diagonal

Red CurveData
Default: [[0.0,0.0],[255.0,255.0]]

Red curve (control points)

Green CurveData
Default: [[0.0,0.0],[255.0,255.0]]

Green curve (control points)

Blue CurveData
Default: [[0.0,0.0],[255.0,255.0]]

Blue curve (control points)

Mask

Mask FitChoice
Default: None (native size)
Mask connected

How the mask is sized when it doesn't match the image. None: center at native size, no scaling. Stretch: scale to exactly match image dimensions. Fit: scale to fit inside image, preserving aspect ratio. Fill: scale to fill image, cropping overflow

  • None (native size)Center the mask at its native size — no resizing. Unmasked regions are unaffected.
  • StretchStretch the mask to exactly match the image dimensions. May distort the mask shape.
  • Fit (letterbox)Scale the mask to fit inside the image, preserving aspect ratio. Letterboxes where needed.
  • Fill (crop)Scale the mask to fill the image, preserving aspect ratio. Crops edges if aspect ratios differ.

Usage Tips

Section titled “Usage Tips”
  • An S-curve (lift shadows, push highlights) is the classic contrast boost.
  • Pull the bottom-left point up to lift shadows for a matte/faded look.
  • Use individual channel curves to create cross-process or film emulation effects.
  • Double-click or Ctrl+click on the curve to add control points. Right-click or Alt+click a point to remove it.
  • Connect a mask input to apply the curve adjustment to only part of the image.
Section titled “Related Nodes”