SMC Affine Low / High Split

SMC Affine Low / High Split (class SMCAffineLowHighSplit) is the affine path's frequency splitter. It takes an image, blurs it with a Gaussian at a given sigma, and outputs low (the blur) and high (the image minus the blur). Nothing more.

That description makes it sound like a duplicate of the anchor-guided path's SMC Frequency Split, and functionally it is - but there's one real difference that matters: this pair is built to recombine. SMCFrequencySplit returns the high layer as a visualization (high * 0.5 + 0.5) that you can't cleanly add back, while this node returns the raw residual, ready to be summed with low in SMC Affine Recombine. So this is the "work" splitter, and the other is the "look" splitter.

The other difference is the control: this one takes sigma (default 8), a standard-deviation-style blur amount matching the affine profile's stable_sigma, rather than the anchor-guided path's blur radius. Use a sigma near 8 and you're splitting exactly the way the affine drift estimation does internally - which makes it handy for inspecting what the estimator actually sees before it fits the affine.

Inputs and outputs

• Input: image (anything) and sigma (0–64, default 8).
• Outputs: low - the blurred, low-frequency structure layer; high - the residual detail, as raw signed values. ComfyUI previews of high may look odd (values can sit outside 0–1 and drift negative), which is expected - it's not meant to be looked at, it's meant to be recombined.

Use it this way

The natural pattern: split an image, modify one layer (say, gently blur or boost the low to fix washout, or scale high), then recombine with SMC Affine Recombine's high_strength knob to control how much detail survives. It's a manual, transparent way to fix low-frequency tone drift without the full compand machinery - a poor man's frequency-band EQ for images.

Install & gotchas

Same pack, trivial install:

cd ComfyUI/custom_nodes
git clone https://github.com/xmarre/ComfyUI-StableManifoldCompander

or ComfyUI Manager (search "Stable Manifold Compander"). No extra dependencies. Two notes: sigma of 0 returns the image unchanged as low (with an empty high), so don't set it to zero expecting a sharp detail layer; and the high output is signed, so if you wire it straight into a Save Image node you'll get clipped/negative-looking garbage - recombine it first.