🌈 S42 CutFlow Chromatic Aberration

Chromatic aberration - the red/blue fringing you see at the edges of cheap lenses - is an optical flaw that audiences have learned to read as "real footage." AI video has none of it, which is one small reason generated clips look too clean. S42CF Chromatic Aberration lets you add it back, and it spans the full range from a subtle 1–2px realism tick to a full-blown RGB-split glitch melt, all from a single strength slider. It sits in the Filters category, and it's one of those "one parameter, huge personality" nodes.

The three inputs:

• strength (0–30, default 3) - the pixel offset between color channels. The tooltip's scale is the one to internalize: 1–3 is subtle lens fringe, 5–10 is clearly visible, 15+ is extreme and stylistic. Start at 2 and only push past 10 if you're doing a glitch aesthetic.
• mode - radial (default) or linear. Radial offsets the channels more toward the edges of frame, matching how real lenses behave - the center stays sharp, the corners fringe. Linear shifts the whole image uniformly in one direction, which is the look used in glitch/cyberpunk graphics where the whole frame splits. Realism → radial. Style → linear.
• angle (0–360) - the direction of the shift in linear mode, or the rotation of the radial pattern. You'll set it once for the effect direction and mostly leave it.

The mechanism is what you'd guess and what makes it cheap and deterministic: it separates the RGB channels and shifts them by strength pixels relative to each other, with the offset growing with distance from center in radial mode. No model, no VRAM, instant on any IMAGE batch.

Where it fits: after your grade, before delivery, as a finishing pass. The trick people actually use it for - and the KB's post-processing essay lands on this exact point - is that imperfection sells realism: a 1–2px radial fringe reads as "this came off a real camera," and it's the cheapest lens-character move in the toolbox. The other direction, cranked-up glitch, is equally legitimate as a music-video / horror look and pairs naturally with the pack's Glitch FX node.

The honest warning is the same one that applies to all "add an optical flaw" nodes: a little is invisible and great, a lot is intentional and great, and the whole range between is where it looks like a mistake. There's no in-between setting that reads as accidental good taste - you're either doing realism or you're doing VFX. Pick your lane.

Installing it

S42-CutFlow install: ComfyUI Manager → search "S42 CutFlow" → Install → restart, or:

cd ComfyUI/custom_nodes
git clone https://github.com/GeekyGhost/S42-CutFlow.git
pip install -r S42-CutFlow/requirements.txt

One-line requirements (opencv-python-headless); the shift is pure torch tensor work. "[S42 CutFlow] Loaded ..." on restart confirms the pack.

The takeaway

Two real uses, one slider apart: strength 2 in radial mode for realism, strength 15+ in linear mode for glitch. The middle is a trap. Go commit to one.