How to add glow and light effects to a photo

Intermediate6 minutesUpdated 29 October 2026

Quick answer

In Lil Cactus, open your photo, choose Layer then Duplicate Layer, then Filter then Render then Bloom… For the evening-street sample, set Amount to 100%, Radius to 55 px and Highlight threshold to 35%, leave Soft threshold at its 25% default, and click Apply. Compare the glowing copy with the original using its eye in Layers. Choose File then Save As then Lil Cactus Project… to keep both layers, then File then Export then JPEG… for a finished copy.

A stone street at dusk before and after soft warm halos spread from its café lights and street lamp — The lights gain a softer halo; the window frames and stonework remain readable. Drag the handle to compare.

The lights gain a softer halo; the window frames and stonework remain readable. Drag the handle to compare.

Time: 6 minutes
Level: Intermediate
You need: A photo with bright lamps, windows or other highlights
Works with: RGB photo layers, including JPEG and PNG

Open the sample in Lil Cactus Use your own photo

Free, no sign-up. Your photo stays on your computer.

Bloom spreads light from bright parts of a photo into their surroundings. A small amount can make lamps or sunlit edges feel softer. The evening sample has bright light sources against dark stone, so the change is easy to see.

Apply the filter to a copy of the photo. These filters change the copy’s pixels, while the original underneath gives you a comparison and a fresh starting point for another version.

Add highlight glow in five steps

Open the photo and keep an original layer
Choose File then Open… and open your photo, or open the sample from this page. Choose Layer then Duplicate Layer.
The selected Background copy sits above Background. Apply the glow to that copy.
Open the photograph as a document.
Keep the original below the filtered copy.
Set the strength and width of Bloom
Choose Filter then Render then Bloom… For the sample, set Amount to 100% and Radius to 55 px.
Amount controls the glow’s strength. Radius controls how far the light spreads. Leave the dialog open for the highlight settings.
Bloom spreads existing bright areas into a glow.
Set strength and width first; change the threshold in the next step.
Choose which highlights glow and apply
Set Highlight threshold to 35%. Higher values restrict the effect to brighter highlights; lower values include more of the picture. Leave Soft threshold at 25%, its default, for a gradual transition near the cutoff.
Click Apply and wait for the filter to finish. The café lights and lamp now spread soft warm halos into the nearby stone and sky.
Tip To revise these settings now, before using the eye in step 4, press Ctrl+Z or ⌘Z and repeat steps 2–3.
Use the lower threshold for this sample’s warm windows as well as its pale lamp.
Compare the lights and inspect their edges
Click the eye beside Background copy in Layers to see the original. Click it again to restore Bloom.
Compare the whole photo, then the lamp detail below. Its dark metal frame should still read inside the halo. Check the café’s window divisions too, so the glow adds softness without washing away their shape.
The eye switches between Bloom and the untouched original.
Original left, Bloom right. The halo spreads beyond the lamp’s housing.
Save the layers and export the picture
Choose File then Save As then Lil Cactus Project… to keep the original and glowing copy. After that, File then Save saves the project. Choose File then Export then JPEG… and click Export for a new finished photo.
If you stay with the opened JPEG, File then Save writes a flat picture in that format; its first Save opens Save Image.
Keep both photo layers for another version later.
Export a combined JPEG to a new file.
Export a finished copy for sharing.

Use Diffuse Glow for a softer finish

For this example and the Lighting example below, start from a fresh original: choose File then Open…, open evening-lights.jpg again and choose Layer then Duplicate Layer.

Choose Filter then Stylize then Diffuse Glow… On the sample, raise Amount from its 25% default to 60%. Keep Radius at 18 px, Detail softness at 20% and Shadow protection at 70%, their defaults. Click Apply.

Diffuse Glow spreads a gentle haze through the middle tones as well as the highlights. Detail softness controls how much fine detail softens. Shadow protection reduces the change in dark areas; it does not make them immune to the effect.

Filter menu with Stylize open and Diffuse Glow ringed — Choose Diffuse Glow for a broader soft finish.

Diffuse Glow dialog showing Amount 60 percent, Radius 18 pixels, Detail softness 20 percent and Shadow protection 70 percent, with Amount and Apply ringed — Raise Amount to make the sample’s diffuse haze visible.

Matched café window crops, original left and Diffuse Glow right, with a softer luminous finish in the window — Original left, Diffuse Glow right. The light spreads through the window’s middle tones.

Brighten a chosen area with Lighting

Start with another fresh original copy as above. Choose Filter then Render then Lighting…

EV measures a brightness change: positive values brighten the affected area, and negative values darken it.

Set Light center X to 70%, Light center Y to 65% and Light radius to 35%. Leave Light strength at +1 EV, Ambient light at 0 EV and Light softness at 65%, their defaults. Click Apply.

X is measured from the left and Y from the top. These values place a soft pool of brightness on the wet street below and to the left of the lamp. Light radius is a percentage of the shorter image side. Ambient light affects the whole image; keep it at 0 here to leave areas outside the pool unchanged.

Filter menu with Render open and Lighting ringed — Lighting changes brightness around a chosen position.

Lighting dialog with whole Light center X 70 percent, Light center Y 65 percent, Light radius 35 percent and Apply ringed — Place the pool on the street, with a soft edge and no global ambient change.

A cropped region of the original wet street and right-hand buildings before Lighting — Before Lighting: the street below the lamp is darker.

The same street crop after Lighting, with a brighter soft pool across the wet stones — After Lighting: the pool opens up the street while the original reflections remain visible.

Fix common problems

Once a filter is applied and you have compared or saved it, start a new version from the original: hide Background copy with its eye, select the Background row and choose Layer then Duplicate Layer. Apply new settings to the selected fresh copy.

The whole picture looks hazy

For Bloom, use a higher Highlight threshold so fewer tones produce glow. Diffuse Glow deliberately reaches more of the middle tones.

The halo reaches too far

Use a smaller Radius in Bloom or Diffuse Glow. Keep the glow close enough to the light source that nearby shapes remain readable.

The glow is too faint

If Amount is below 100%, raise it first. At 100% in Bloom, lower Highlight threshold to include more tones. A larger Radius spreads the glow over more space and may make the center less intense.

The Lighting change covers the whole photo

Check Ambient light is 0 EV, then reduce Light radius to limit the pool. Set its X and Y percentages to the part of the picture you want to brighten.

Layers strip with the old Background copy visibility eye and the whole original Background row ringed — Hide the old effect, select the original, then duplicate it for another version.

What to do next

Coming from another editor

Photoshop: Filter › Filter Gallery › Distort › Diffuse Glow.

Glow and light effects: questions and answers

What is the difference between Bloom and Diffuse Glow?

In Lil Cactus, Bloom extracts bright highlights and spreads their light. Diffuse Glow gives a broader soft finish through the middle tones, with separate Detail softness and Shadow protection controls.

How does Highlight threshold affect glow?

In Lil Cactus’s Bloom filter, a higher Highlight threshold limits the effect to brighter highlights. A lower threshold includes more tones, while Soft threshold smooths the transition around the cutoff.

Can I change glow settings after saving?

Yes, by making a fresh copy of the original layer in the Lil Cactus Project and applying new settings. The project keeps the original and filtered copy; the applied pixel filter has no saved settings dialog to reopen.

How is Lighting different from Bloom?

Lil Cactus’s Lighting brightens or dims an area around an X/Y position, with a separate whole-image Ambient light control. Bloom spreads light from highlights already in the photo.

Is my photo uploaded when I add glow?

No. Lil Cactus runs Bloom, Diffuse Glow and Lighting on your device.

Published 29 October 2026 · Last checked 29 October 2026