Inner Shadow

Casts a colored, blurred shadow INSIDE the shape near its edges — the "inside" complement to Drop Shadow.

Category: Effects Menu path: Effects > Inner Shadow

Ports

Port	Type	Direction	Description
in	imageRgba16f	input	Input image
out	imageRgba16f	output	Image with the inner shadow composited inside it

Parameters

Param	Type	Default	Description
color	color	black (0,0,0,1)	Shadow color in linear space.
offset	vec2	(5, 5)	Directional shadow displacement in pixels (X, Y). Positive X = shadow on the right inner edge, positive Y = bottom inner edge. Keyframeable.
blur	scalar	10	Gaussian blur radius for the shadow softness. 0 = hard inner edge. Keyframeable.
opacity	scalar	0.75	Shadow opacity. 0 = invisible, 1 = fully opaque shadow. Keyframeable.
spread	scalar	0	Controls shadow alpha hardening. 0 = soft natural falloff, 1 = hard edge before blur. Keyframeable.
output	enum	Composite	Composite darkens the input in place. Shadow Only outputs just the colored shadow (transparent elsewhere). Matte outputs a grayscale intensity mask.

Expose Channels

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

Port	Type	Overrides
opacity_in	scalar	opacity

How It Works

The inner shadow is a three-pass operation that mirrors Drop Shadow but works on the inverse alpha:

1. Extract pass: The shape's alpha is sampled at an offset position, then inverted (1 - alpha). Near an edge, the offset sample lands outside the shape (alpha 0 → inverse 1 → strong shadow on the offset side); deep in the interior the inverse is 0 (no shadow). The result is hardened by spread, scaled by opacity, and tinted with the shadow color.
2. Blur pass: The inner source is gaussian-blurred for soft falloff.
3. Composite pass: The blurred source is clipped to the inside of the shape (blurred.a × input.a) so the effect only appears within the existing silhouette, then mixed toward the shadow color. The output alpha equals the input alpha, so the silhouette is never enlarged.

Because the effect is clipped to the input alpha it never extends beyond existing content bounds — unlike Drop Shadow, it does not expand the layer's bounds.

Usage Examples

Basic: Engraved / inset look

1. Add an Inner Shadow node after your text or shape
2. Set offset to (3, 3), blur to 6, opacity to 0.6
3. The content looks recessed/cut into the surface

Creative: Vignette inside a shape

1. Set offset to (0, 0) so the shadow comes evenly from all edges
2. Increase blur to 40 and opacity to 0.5
3. Darkens the rim of the shape for a soft inner vignette

Advanced: Drive a grain/texture mask

1. Set output to Matte
2. Pipe the grayscale mask into a Grain or Colorize node
3. Concentrate the downstream effect along the inner edges of the shape

Tips

• Spread 0 gives the most natural soft falloff; spread 1 makes a crisp inner line before blur
• Offset (0, 0) produces an even inner glow-of-darkness from every edge; non-zero offset biases it directionally (like a light source)
• Shadow Only is useful for compositing the shadow with a custom blend mode downstream via Merge
• Offset is in comp pixels, so it stays consistent across Draft / Preview / Full quality

Related Nodes

• DropShadow — the "outside" complement (shadow behind the shape)
• InnerGlow — same pipeline but brightens instead of darkens
• Glow — outward bloom from bright areas
• Matte — combine with the Matte output for custom inner masks