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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.

High Pass keeps only the high-frequency content of an image: the small-scale variation that the matching blur would smooth away. The result is mid-gray plus the local deviations from the blur, so flat regions go gray while edges and texture pop out.

Two modes are available. Per-channel processes R, G, B independently and is the default. Luminance runs the high-pass on luminance only and broadcasts to all channels, which avoids the colored fringes that per-channel mode can produce on saturated edges. The radius slider goes up to 500 px so large-radius texture flattening stays interactive.

An optional mask input limits the effect to specific regions of the image, blending the result with the original wherever the mask is dark.

Parameters

Section titled “Parameters”

Pins

ImageImage
InputRequired
MaskMask
InputOptional
ImageImage
Output

Filter

ModeChoice
Default: Per-channel

Per-channel: process R/G/B independently (Photoshop-style). Luminance: high-pass BT.709 luma only

  • 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

Preserve AlphaToggle
Default: true

On: pass alpha through. Off: also high-pass the alpha channel

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”
  • Small radius (1-4 px) plus Composite in Overlay or Soft Light gives you a controllable sharpen.
  • Medium radius (3-15 px) is the typical setting for frequency-separation portrait workflows.
  • Large radius (50-150+ px) flattens uneven lighting on photographed textures so they tile cleanly.
  • Use Luminance mode when you only care about detail and want to avoid color shifts at edges.
Section titled “Related Nodes”