APNext Bloom FX

Bloom is that soft glow that spills out of the bright parts of an image - the halo around a lamp, the shimmer off a highlight, the dreamy bleed you see in film and games. APNext Bloom FX adds it as a post-processing pass inside ComfyUI, so you can bake it into a generation instead of round-tripping through Photoshop. It's a small effect, but it's one of the cheapest ways to make a flat render feel like it has real light in it.

This is an image-effect node, not a prompt or model node. It takes a finished image (after your VAE decode) and hands back a modified one. No model runs, no API key, nothing downloads.

How it works

The node finds the pixels brighter than your threshold, blurs that bright region by blur_radius, scales it by intensity, and composites it back over the original using the blend_mode. That's the classic bloom recipe: isolate highlights, blur them, add the blur back. Everything below the threshold is untouched, so shadows and midtones stay crisp while the highlights glow.

Inputs and outputs that matter

• images - the image to process. Wire your VAE Decode output in here.
• threshold (0–1, default 0.8) - how bright a pixel has to be before it blooms. Lower it to make more of the image glow; raise it to restrict the effect to only the hottest highlights.
• intensity (0–5, default 1) - how strong the glow is. This is your main dial. Small moves go a long way; past 2 or so it gets hazy fast.
• blur_radius (1–50, default 15) - how far the glow spreads. Tight radius for a subtle sheen, wide for a soft-focus dream look.
• blend_mode - additive (brightest, can blow out), screen (softer, safer), or overlay (more contrast-preserving). Screen is the forgiving default.

The single output is image - feed it to a Save Image, or chain it into another FX node.

Installing it

ComfyUI Manager: search comfyui_dagthomas, install, restart. Or manually:

cd ComfyUI/custom_nodes
git clone https://github.com/dagthomas/comfyui_dagthomas
cd comfyui_dagthomas
pip install -r requirements.txt

The image-FX nodes lean on blend-modes and Pillow from the requirements, so let the install finish. No API key, no model files.

Common issues

The one mistake everyone makes is overdoing it - bloom is a seasoning, not a sauce. Crank intensity and drop threshold and your highlights turn into a milky white smear that eats detail. Start at intensity 0.5–1.0 with the default 0.8 threshold and nudge from there. If the glow looks blocky rather than smooth, raise blur_radius.

additive blend on an already-bright image will clip the highlights to pure white; switch to screen if you're losing detail in the glowing areas. And because this is a post-decode effect, it stacks nicely with the pack's other film-look nodes - a touch of bloom under Film Halation and a little grain sells a convincing analog look better than any single effect alone.