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Levels

Node icon
Color

Adjusts the tonal range with input/output levels and gamma, per-channel or master.

Levels is a fundamental tonal adjustment. The input range clips shadows (Input Black) and highlights (Input White), compressing the tonal range. Gamma adjusts midtones: values below 1.0 darken, above 1.0 brighten. The output range then remaps the result to a new brightness window.

Each channel (Red, Green, Blue, Alpha) can be adjusted independently, or use Master to adjust all at once. The histogram at the top of the panel shows every color channel’s distribution together and updates live as you drag the sliders. On a single-channel image, the adjustment applies to that one channel and the output stays single-channel.

Parameters

Section titled “Parameters”

Pins

ImagePixels
InputRequired
MaskMask
InputOptional
ImagePixels
Output

Color

ChannelChoice
Default: Master

Which channel to adjust (Master affects R/G/B equally)

  • MasterAdjust all RGB channels together, affecting overall brightness and contrast.
  • RedAdjust only the red channel, affecting red/cyan color balance.
  • GreenAdjust only the green channel, affecting green/magenta color balance.
  • BlueAdjust only the blue channel, affecting blue/yellow color balance.
  • AlphaAdjust the alpha (transparency) channel, affecting opacity levels.
Master In BlackNumber
Default: 0.000 Range: 0.000–1.000

Master black-point input

Master In WhiteNumber
Default: 1.000 Range: 0.000–1.000

Master white-point input

Master GammaNumber
Default: 1.00 Range: 0.01–9.99

Master midtone gamma

Master Out BlackNumber
Default: 0.000 Range: 0.000–1.000

Master output black floor

Master Out WhiteNumber
Default: 1.000 Range: 0.000–1.000

Master output white ceiling

Red In BlackNumber
Default: 0.000 Range: 0.000–1.000

Red black-point input

Red In WhiteNumber
Default: 1.000 Range: 0.000–1.000

Red white-point input

Red GammaNumber
Default: 1.00 Range: 0.01–9.99

Red midtone gamma

Red Out BlackNumber
Default: 0.000 Range: 0.000–1.000

Red output black

Red Out WhiteNumber
Default: 1.000 Range: 0.000–1.000

Red output white

Green In BlackNumber
Default: 0.000 Range: 0.000–1.000

Green black-point input

Green In WhiteNumber
Default: 1.000 Range: 0.000–1.000

Green white-point input

Green GammaNumber
Default: 1.00 Range: 0.01–9.99

Green midtone gamma

Green Out BlackNumber
Default: 0.000 Range: 0.000–1.000

Green output black

Green Out WhiteNumber
Default: 1.000 Range: 0.000–1.000

Green output white

Blue In BlackNumber
Default: 0.000 Range: 0.000–1.000

Blue black-point input

Blue In WhiteNumber
Default: 1.000 Range: 0.000–1.000

Blue white-point input

Blue GammaNumber
Default: 1.00 Range: 0.01–9.99

Blue midtone gamma

Blue Out BlackNumber
Default: 0.000 Range: 0.000–1.000

Blue output black

Blue Out WhiteNumber
Default: 1.000 Range: 0.000–1.000

Blue output white

Alpha In BlackNumber
Default: 0.000 Range: 0.000–1.000

Alpha black-point input

Alpha In WhiteNumber
Default: 1.000 Range: 0.000–1.000

Alpha white-point input

Alpha GammaNumber
Default: 1.00 Range: 0.01–9.99

Alpha midtone gamma

Alpha Out BlackNumber
Default: 0.000 Range: 0.000–1.000

Alpha output black

Alpha Out WhiteNumber
Default: 1.000 Range: 0.000–1.000

Alpha output white

Display

Show HistogramToggle
Default: true

Render the histogram overlay above the sliders

Mask

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

How the connected color image is read as a mask. Luminance: the image's brightness. Alpha: the image's transparency. Red / Green / Blue: a single channel

  • 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: 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, 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”
  • Drag Input Black right to clip dark noise; drag Input White left to boost dim highlights.
  • Use Output Black > 0 to lift the shadows (no pure black) for a faded/matte look.
  • Adjust individual channels to correct color casts. For example, reduce Input White on Blue to warm up an image.
  • Connect a mask input to apply the tonal adjustment to only part of the image.
Section titled “Related Nodes”