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Curves

Node icon
Color

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

The Curves node applied to a source image: original (left) and result (right).
Side-by-side comparison: the original image on the left and the same image after the Curves node on the right.

Each point on a curve maps an input brightness to an output brightness, joined by a smooth spline that never doubles back. The Master curve affects all RGB channels; the R, G, and B curves adjust colors independently. On a single-channel image, Curves adjusts that one channel and keeps the output single-channel.

Curves is more precise than Levels because it can target specific tonal ranges, such as just the quarter-tones or three-quarter-tones.

The editor shows every channel’s curve at once, with inactive channels dimmed behind the active one, over the source image’s histogram. On a batch, the histogram is the frame the Preview shows. Selecting a control point shows its exact input and output values.

Texture sets

Section titled “Texture sets”

On a texture set or a library, a Map row at the top of the panel picks the one map Curves edits, such as the Roughness, and every other map passes through untouched. On a one-channel map such as the Roughness the Channel row reads Master. See Changing one map.

Parameters

Section titled “Parameters”

Pins

ImagePixels or Texture
InputRequired
MaskMask
InputOptional
ImagePixels or Texture
Output

Color

MapChoice
Default: Base Color
Texture set or library wired

Which map of the texture set this node edits. Every other map passes through unchanged. Shown while a texture set or a library is wired

  • Base ColorWork on the set's Base Color. The first map for the color and tone nodes.
  • NormalWork on the set's Normal. Offered on Normal Map (rescale its intensity) and the nodes that read a map into a selection; a color node never edits a direction.
  • RoughnessWork on the set's Roughness, a linear 0 to 1 map with one channel.
  • MetallicWork on the set's Metallic, a linear 0 to 1 map with one channel.
  • Ambient OcclusionWork on the set's Ambient Occlusion, a linear 0 to 1 map with one channel.
  • HeightWork on the set's Height, a linear map that can pass 0 and 1.
  • OpacityNever offered: the Opacity is the set's cutout, which Mask Apply edits.
  • EmissiveWork on the set's Emissive color.
ChannelChoice
Default: Master

Which curve to edit

  • MasterAdjust all RGB channels together with a single curve.
  • RAdjust only the red channel curve.
  • GAdjust only the green channel curve.
  • BAdjust only the blue channel curve.
Master CurveData
Default: Linear

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

Red CurveData
Default: Linear

Red curve (control points)

Green CurveData
Default: Linear

Green curve (control points)

Blue CurveData
Default: Linear

Blue curve (control points)

Mask

Mask FromChoice
Default: Luminance
Color image connected to the mask input

How the connected color image is read as a mask

  • LuminanceRead the image's brightness as the mask. The default.
  • AlphaRead the image's transparency as the mask.
  • RedUse the red channel as the mask.
  • GreenUse the green channel as the mask.
  • BlueUse the blue channel as the mask.
Mask FitChoice
Default: None (native size)
Mask connected

How the mask is sized when it doesn't match the image

  • None (native size)Center the mask at its native size, with 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”
  • Double-click or Ctrl+click the curve to add a point. Right-click or Alt+click a point to remove it (the two endpoints stay).
  • An S-curve (darken the shadows, brighten the highlights) is the classic contrast boost.
  • Drag the bottom-left point up to lift the blacks for a matte, faded look.
  • Use individual channel curves for cross-process or film emulation looks.
  • Connect a mask to adjust only part of the image.
Section titled “Related Nodes”