Add a glow

Glow spreads the light from bright areas into the dark ones around them. Use it for a dreamy look, or to make lights feel bright. It is off until you switch it on.

Add a glow

1. Open Exponential Glow in the right column.
2. Click the power button in the section header. Until you do, the section is dimmed and does nothing.
3. Drag Intensity up from its default of 1.00 or down toward 0, then shape the glow with the other controls.

Control	Range	Default	What it does
Intensity	0 to 5	1.00	How bright the glow is
Size	0 to 500 px	20 px	How wide the tightest part of the glow is
Falloff	0 to 1	0.75	Low keeps the glow tight; high lets it spread far and wide
Threshold	0 to 2	1.00	How bright a pixel must be to cast a glow
Softness	0 to 1	0.20	How gradually pixels near the Threshold fade into the glow
Tint Red, Tint Green, Tint Blue	0 to 2	1.00 each	Colors the light that glows

Choose what glows

Threshold is the main control, and a low value means more of the photo glows. A high value keeps the glow to the brightest highlights. As starting points, try 1.5 to 2.0 for glow from specular highlights only, 0.8 to 1.5 for the brighter areas, and 0.3 to 0.6 for a soft glow over the whole photo.

Threshold is measured after your tone edits, so raising Exposure makes more of the photo glow.

To color the glow, lower the tints you don’t want. Lowering Tint Blue and Tint Green gives a warm glow.

See only the glow

Turn on Preview Effect Only to see the glow by itself on black. It turns off by itself when you change anything outside the Glow section.

Note

Glow and Halation work well together. Glow spreads light evenly around bright areas; Halation adds a warm fringe along their edges.

Glow part of a photo

Glow works on the layer selected in the Layers pane. A masked layer can make one lamp bloom and leave the rest alone. See Layers.

Technical details: why it looks like real light

Glow is added in linear light, before the display transform, so the glow and the highlight that casts it are tone-mapped together. A very bright glow rolls off into white smoothly and never clips. That is why it reads as light, not as a gray haze.

The glow is the sum of eight blurs, each twice as wide as the last (starting at Size), each weighted a little less than the one before. Falloff sets that weight, from one half at 0 to equal at 1. This gives a bloom with a bright core and a long tail, like real lens bloom, instead of the single narrow blur of a basic glow. The widest blur is capped at half the photo’s long side. Size is set in full-resolution pixels and scaled to the preview, so the look is the same at any zoom.

Within a layer, the spatial effects run in this order, after the tone and color edits:

Halation runs before Glow so the glow doesn’t treat the halation fringe as a light source.