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High Pass

High Pass
Filter

Isolates detail by subtracting a blurred copy from the original. The result is mid-gray where the source is locally flat, with bright and dark deviations at edges and texture.

The High Pass 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 High Pass node on the right.

High Pass keeps only the small-scale variation that a blur of the same Radius would smooth away. Flat regions go gray while edges and texture stand out. Mode Luminance avoids the colored fringes the default Per-channel can produce on saturated edges.

Parameters

Section titled “Parameters”

Pins

ImagePixels
InputRequired
MaskMask
InputOptional
ImagePixels
Output

Filter

ModeChoice
Default: Per-channel
  • Per-channelProcess R, G, B independently. May produce colored fringes on saturated edges.
  • LuminanceRun the high-pass on BT.709 luminance only and broadcast to all channels. Avoids color fringing.
RadiusNumber · px/%
Default: 3.0 Range: 0.1–500.0 px / 0–100%

Gaussian blur radius for the high-pass extraction.

  • Small (1-4 px): detail sharpening.
  • Medium (3-15 px): frequency separation.
  • Large (50-150+ px): texture flattening / delighting.
Preserve AlphaToggle
Default: true
  • On (default): pass alpha through unchanged.
  • Off: also high-pass the alpha channel.

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”
  • Sharpening: a small Radius (1 to 4 px), composited over the original with Composite in Overlay or Soft Light, gives a controllable sharpen.
  • Frequency separation: a medium Radius (3 to 15 px) is the typical portrait retouching setting.
  • Texture flattening: a large Radius (50 to 150 px or more) removes uneven lighting from photographed textures so they tile cleanly.
Section titled “Related Nodes”