Glow (Bloom)
Bright parts of the layer radiate light into the darker parts.
Bloom is not a silhouette effect. It reads the layer's own brightness, keeps only the pixels above a threshold, blurs them, and adds that back on top. Bright areas bleed; dark areas are untouched.
That difference matters. Outer Glow puts light around a shape. Bloom puts light around whatever is bright *inside* the shape — a white highlight on a photograph, the lit part of a gradient, the bright stroke on dark type.
When to reach for it#
- Photographic and 3D-looking imagery where highlights should feel over-exposed.
- Anything with a strong internal contrast range.
- Making a gradient or a shader look like it emits rather than reflects.
How it works#
Threshold picks what counts as bright. Everything above it is copied out, blurred by Radius, multiplied by Intensity, and added back. Because it adds rather than blends, bloom can only ever brighten — it will never darken anything.
Parameters#
The brightness cutoff. Low values bloom almost the whole layer and wash it out; high values bloom only the brightest specular highlights. This is the control that decides whether the effect looks tasteful or like a smeared lens.
How far the bloom spreads. Wide and faint reads as atmosphere; tight and strong reads as glare.
How much of the blurred bright pass is added back.
Keeps the bloom the colour of the source pixels rather than drifting toward white as it saturates. On coloured light this is the difference between a glow and a wash.
Things that catch people out#
Bloom needs internal contrast. A shape with one solid fill either blooms entirely or not at all, depending on which side of the threshold the fill lands. Use Outer Glow for flat artwork.
See also#
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