PostFx Apply

PostFx Apply is the whole point of the ComfyUI-PostFx pack, and the argument it makes is one you should hear early: your generated image is fine, it just doesn't look like it was shot yet. This node slaps a film stock or cinematic grade onto any image batch - Portra 400 skin tones, Cinestill 800T halation, a teal-orange blockbuster pass - deterministically, on the CPU, in a fraction of a second. No model, no API key, no extra VRAM. That's the "cheap deterministic primitive before the expensive generative one" play from the KB's post-processing layer: the same job people routinely waste a whole re-roll (or worse, an img2img pass that rewrites the subject's face) on, done in one node.

The engine underneath is the author's postfx pipeline, a numpy-based processor that ComfyUI-PostFx wraps. Everything runs on CPU because everything is classic pixel math: color transforms, grain, vignette, halation, sharpen. A theme is a full look (color grade plus grain and lens character) defined in YAML - there are 31 built in, named after real stocks and industry grades. A condition is a separate axis that scales only the texture stuff - grain, chroma noise, halation - to match a shooting situation, without touching color. That split is the clever bit: one theme stays consistent across conditions because the grade doesn't move, only the "how was this lit/scanned" texture does.

Here's what you actually set:

• theme - the 31-entry dropdown, default 01_portra_400. Picking this alone gets you 80% of the value.
• condition - neutral (default), day_outdoor, overcast, indoor_evening, neon_night, night_flash. Start at neutral, then try neon_night on a city shot - it's a vibe.
• strength - 0.0 to 1.5, default 1.0. Linearly blends the whole effect with the original; 0 is untouched, >1 is deliberately overdone. This is your "keep it subtle" knob.
• seed and batch_seed - grain is deterministic (same seed, same grain). batch_seed = increment gives each frame its own grain, which you want for animation or video so the noise doesn't crawl in a fixed pattern.

The optional inputs are where it gets interesting. A look connected from a PostFx Theme / Custom Look / LUT node overrides the theme dropdown entirely - that's how the pack's chain workflow works. A mask limits the effect to where the mask is white and blends back to the original elsewhere (the code does a straight original * (1-mask) + effect * mask), which is handy if you want the grade on a subject but not the background. Output is a single image of type IMAGE, straight into Save Image or onward to upscaling.

Installing is ComfyUI Manager (search ComfyUI-PostFx) or the manual route:

cd ComfyUI/custom_nodes
git clone https://github.com/0xBeycan/ComfyUI-PostFx.git
pip install -r ComfyUI-PostFx/requirements.txt

Restart ComfyUI and the nodes appear under PostFx. The only real dependency is postfx>=1.0 (plus numpy and opencv under the hood) - tiny, CPU-only, no model downloads. There is no giant checkpoint to fetch.

Where people get burned: forgetting that a connected look silently ignores your theme dropdown (it's by design - the tooltip says so, but it reads as a bug the first time). And if grain looks wrong at your resolution, don't panic - grain scales with image size by design, so a look reads the same at 512 or 2048. Deterministic and resolution-safe is the whole selling point, and the pack delivers it.