False Color Monitor

Every camera department on earth uses false colour to check exposure without reading a scope, and for good reason: your eye is terrible at judging absolute brightness and excellent at judging colour. Paint the luminance zones in fixed colours and "am I clipping?" becomes a glance instead of a histogram squint.

This is that, for ComfyUI.

The zone map

It's a broadcast-style exposure ramp keyed to display-referred luma, and the mapping is fixed:

• Black below 1% - absolute black, signal loss
• Purple 1–4% - deep shadow, pedestal
• Blue 4–10% - shadow detail
• Teal 10–16.5% - low midtone
• Green 16.5–23.5% - that band is 18% grey, i.e. correctly exposed mid-grey
• Nothing 23.5–70% - normal tones pass through untouched
• Yellow 70–80% - bright, watch your headroom
• Orange 80–90% - highlight warning
• Red 90–99% - near clip, do something
• Zebra above 99% - clipped, alternating black stripes

That green band is the load-bearing part. In a properly exposed shot, skin, grass and mid-tone grey land in it; if your subject is teal, you're a stop under, and if it's yellow, you're a stop over. The zebra stripes at the top are the other one - they're the same signal a camera operator uses to see, without any numbers, exactly how much of the frame is unrecoverable.

Inputs and outputs

The required two are image and strength (1.0 = full false colour, 0 = off, so you have a clean bypass dial with no rewiring).

hdr_peak is the interesting optional. Luma is divided by it before the zone lookup, and 1.0 is the SDR setting. For scene-linear HDR where 1.0 is 203 nits, a 1000-nit peak is about 4.93 - so the zone map still means something on a float image, which most false-colour tools can't say.

input_encoding is the one to get right: Linear Rec.709 (default, preserves legacy behaviour), sRGB, or Rec.709. sRGB and Rec.709 are decoded before the luminance measurement, so the zones land where they should. This is a fix from a recent release - earlier builds measured display values directly and the bands were shifted.

Outputs: passthrough (the image, untouched) and false_color (the diagnostic overlay). Wire false_color to a preview and passthrough onward to whatever comes next; that's the whole pattern.

The three caveats the author states

Read the tooltip, because it's unusually candid:

1. Rec.709 primaries only. Convert other primaries into Rec.709 before connecting. It won't convert for you.
2. The output is an SDR diagnostic image, not HDR mastering. It's a monitor, not a transform.
3. "Normal tones pass through" - so a big chunk of your image is unmodified. Don't hand the false-colour output to a client as a look.

Where it belongs

Genuine on-set use in ComfyUI isn't really a thing, so this is a grading and QC tool. Two workflows where it earns its place.

Batch QC. Sweep the key light intensity across twelve seeds, run all twelve through the same monitor, and see immediately which ones blow the highlights - with a Contact Sheet of the false-colour outputs, that's one image telling you what happened.

Consistency. A generated sequence where frame 3 sits in green and frame 9 in orange is a shot with drifting exposure, regardless of how pretty both frames look. False colour makes that visible where eyeballing absolutely will not.

There is one honest caveat to the whole approach, and it's from the pack's own known issues: the pro-scope "false colour" mode in the Viewer is a display-level zone map, not ARRI bands. This node is the zone-map style. If you're used to a camera's ARRI false-colour palette - different bands, different colours - this will read as familiar-but-not-the-same, and you'll need to relearn which colour means what rather than trusting muscle memory.

Install

Ships in Radiance. ComfyUI Manager → search Radiance → install, restart, refresh the browser. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/fxtd-studios/radiance.git
cd radiance
python -m pip install -r requirements.txt

Windows portable users should run pip with python_embeded\python.exe. No model downloads, nothing to configure.