LC Bloom

Bloom is the look of light spilling past its source - neon halos, sun flare, that cinematic glow you can't quite get from the raw render. It's also one of those effects people overdo until everything looks like a bad lens flare. LC Bloom is the pack's take: a proper bright-pass bloom with threshold, radius, intensity, and just enough control to keep it tasteful.

The mechanism is the classic compositing recipe, and the source lays it out plainly. It computes luminance (Rec.709 weights), separates the brights from everything else, and then does something smarter than a hard cutoff: a soft knee. There's a hard mask for pixels clearly above threshold, plus a soft, squared ramp around it so the transition from "not glowing" to "glowing" is smooth instead of a harsh ring. The bright regions are then blurred through a Gaussian pyramid - downsample, blur, upsample - which is how you get that wide, soft spill without the huge convolution cost a single giant blur would need. Saturation and exposure give you the final polish on the glow pass.

The controls map onto that recipe directly. threshold (default 0.65) decides how bright a pixel must be before it starts contributing - raise it for a more selective glow, lower it to bloom a wider range. smoothing (0.3) softens the knee; if you see a hard halo edge, raise it. radius (1.0, 0.1–5) is the spread of the glow. intensity (1.0, up to 4) is how much glow gets mixed back in - and it's the one to lean on; at 0 the node is a pass-through. saturation lets you push the glow's color richness (useful because bloom that desaturates can look dusty), and exposure is a brightness trim on the glow itself rather than the whole image.

That's a genuinely useful detail: separating "how much glow" (intensity) from "how bright the glow is" (exposure) from "how much of the image glows" (threshold) means you can fix the three common bloom failures independently. Bad bloom is almost always a threshold set too low (everything glows) or an intensity cranked too high (the image turns into fog).

It's one of the LC image-FX nodes, so you get the on-node preview with the before/after hover wipe - flick between original and bloomed right on the node. And it's listed under the pack's Performance settings, so if you're running heavy graphs you can drop the preview to half-resolution or disable the wipe to keep the UI snappy.

Where people get tripped up: bloom is additive by nature, so feeding it an already-bright image (white background, blown highlights) will amplify what's there - there's no "fix the source" button. Gently lowering threshold and keeping radius modest on bright backgrounds is the reliable path. And if the glow looks muddy rather than clean, check saturation - a saturated glow reads as light, a desaturated one reads as haze.

Single image output, output-node flagged, so it slots in at the end of a chain or just before a save. Install is the one clone:

cd ComfyUI/custom_nodes
git clone https://github.com/lonecatone23/ComfyUI_LC123_nodes

Restart, no pip deps. Start at threshold ~0.65, radius ~1, intensity under 2, and you'll get the glow without the fog.