Advanced Bloom FX (CRT)

This is the biggest single node in the CRT-Nodes FX category by a wide margin - 21 inputs - and it's really two tools stacked into one: a bloom effect, and underneath it, a genuine three-way color grading suite of the kind you'd normally reach for DaVinci Resolve or Lightroom to do. If the sheer number of fields is intimidating, that's a fair reaction; the honest advice is to use maybe four of them at first and ignore the rest until you actually need professional color-grading vocabulary.

Bloom, the part most people came for

Bloom is the classic glow-around-bright-areas effect you'll recognize from game engines and film post - light sources and highlights spill a soft haze into the surrounding image rather than staying hard-edged. The mechanism here is the standard recipe: pixels brighter than bloom_threshold get pulled out, blurred by bloom_radius with bloom_smoothing controlling how soft that falloff is, then added back over the original at bloom_intensity. Four fields, and they're the ones worth learning first - bloom_intensity and bloom_threshold specifically will get you most of the visible effect on their own.

The color-grading half, for when you're ready

Past bloom, the node layers on real colorist tools:

• Basic tone: exposure, lightness, saturation, hue_shift, contrast - the fundamentals, self-explanatory.
• White balance: temperature and tint, plus a color_filter (COLOR) for an overall tint overlay.
• Split toning: split_shadows and split_highlights (both COLOR) with split_balance - this is the classic cinematic teal-and-orange trick, casting one color into your shadows and a different one into your highlights.
• Shadows/Midtones/Highlights (SMH): smh_shadow_color, smh_midtone_color, smh_highlight_color, plus smh_shadow_start/smh_shadow_end and smh_highlight_start/smh_highlight_end defining where each luminance range begins and ends - a three-way color-wheel setup, industry-standard terminology in professional color grading.

None of this is beginner vocabulary, and that's fine - it doesn't need to be. If you already know what split-toning and SMH grading mean, this node gives you real control over them without leaving ComfyUI. If you don't, skip this whole block for now; it's there when you grow into it, not a prerequisite for using the bloom effect.

The input and output that matter most to start

• image - required.
• bloom_intensity (0-2, default 0.5) and bloom_threshold (0-1, default 0.8) - start here, adjust these two first, and leave everything else at default until the bloom itself looks right.

Output is a single IMAGE. It composes naturally with other FX nodes in the pack - Technicolor 2 FX or Colourfulness FX before or after it in a chain, depending on whether you want bloom to react to already-graded color or grade the bloomed result.

How to install it

Part of CRT-Nodes. Via ComfyUI Manager, search CRT-Nodes and install. Manually: git clone https://github.com/PGCRT/CRT-Nodes.git into custom_nodes, pip install -r requirements.txt, restart.

Common issues & troubleshooting

Bloom looks like the whole image is glowing, not just highlights. bloom_threshold is too low - raise it so only genuinely bright pixels get pulled into the glow pass, rather than midtones bleeding in too.

Color looks wildly off after touching temperature/tint/split-toning together. These stack - a strong temperature push plus aggressive split-toning colors compound rather than cancel out. Adjust one block at a time and check the result before layering the next.

Too many knobs, not sure where to start. That's a completely reasonable place to be with this node - set everything except bloom_intensity and bloom_threshold back to default and build up from there only if you specifically want the color-grading features.