Roughen

Displaces an image by a fractal-noise vector field to give alpha edges a torn, rough, hand-drawn look.

Category: Effects Menu path: Effects > Roughen

Ports

Port	Type	Direction	Description
in	imageRgba16f	input	Input image
out	imageRgba16f	output	Roughened result

Parameters

Param	Type	Default	Description
amount	scalar	0.0	Displacement strength in comp pixels. 0 = no effect. Keyframeable.
scale	scalar	50	Noise feature size in comp pixels. Smaller = finer, busier wobble; larger = broad, smooth waviness. Keyframeable.
complexity	scalar	2	fBm octaves, clamped to 1–6. Higher adds finer detail layered on the base wobble. Keyframeable.
evolution	scalar	0.0	Animatable noise phase. Animate it to make the rough edge churn over time. Keyframeable.
seed	scalar	0.0	Varies the noise pattern without changing its character. Keyframeable.

Expose Channels

When enabled (E button on node header), adds input ports that override params via edge connections:

Port	Type	Overrides
amount_in	scalar	amount

How It Works

For each pixel the shader evaluates two decorrelated fractal-Brownian-motion (fBm) noise channels — built from Perlin noise — at the pixel's comp-pixel position divided by scale, offset by evolution (as a 3D noise slice) and seed. The two channels form a 2D displacement vector; the input is then sampled at uv + displacement * amount. Because nearby pixels share nearly the same displacement, solid interiors stay uniform while alpha boundaries wobble — producing the characteristic roughened / torn edge. All noise lookups use the comp resolution (not the render resolution), so the feature size and displacement look identical across Draft / Preview / Full quality. When amount is 0 the node is a pure passthrough and the GPU pass is skipped. Animating evolution flows through normal keyframe param resolution, so no special cache handling is needed.

Usage Examples

Basic: Rough up a shape edge

1. Draw a shape (Rectangle → DrawShape) or render some text
2. Add a Roughen node after it
3. Set amount to ~6 and scale to ~30 for a torn-paper edge

Creative: Animated boiling outline

1. Keyframe evolution from 0 to a few units over the comp duration
2. The roughened edge churns and "boils" like traditional cel animation

Advanced: Driven roughness

1. Enable expose channels and connect a field- or audio-driven scalar to amount_in
2. The edge roughness reacts to your driver (e.g. louder = rougher)

Tips

• Roughen samples within the existing frame, so very large amount values near a tight crop may pull in transparent pixels at the boundary — leave a little padding around content
• Lower scale with higher complexity for a fine, sandy edge; higher scale with low complexity for slow, broad waves
• For a stable look hold evolution constant; for motion animate it rather than seed

Related Nodes

• UVRemap — displacement driven by an explicit map texture instead of procedural noise
• Noise — the procedural noise source, usable as a field or texture elsewhere
• Blur — soften an edge instead of roughening it