Tile ColorFix Patcher

Somewhere in A1111's ControlNet extension there's a checkbox that fixes color drift during tiled upscaling, and most people never think about it twice. This node is that checkbox, ported to ComfyUI as a model patcher for SD and SDXL. It swaps the low-frequency color of a reference image into your generation every denoising step while leaving the model's own detail alone.

The formula is the same one from A1111's hook.py, and it's three operations:

fixed = x0 - blur(x0, k) + blur(reference, k)

Blur both latents, subtract the prediction's color, add the reference's color. weight (0–1) then blends between the fixed and original result, so 1.0 is a full color lock and 0.5 is a tint. The blur is a box filter - a straight average - because that's exactly what A1111 does. At blur_k=8 that's a 17×17 kernel, roughly 136px of blur in image space, which is why the parameter reads as "how far away can color wander before it's corrected".

The inputs that matter

• ref_latent - VAE-encode your reference image and wire it in. For SDXL that's the SDXL VAE; for SD 1.5 the matching VAE for your checkpoint. Wrong VAE, wrong colors - this is the classic beginner trap with anything that touches latents.
• blur_k - frequency split point, default 8, range 3–32. Larger = more aggressive color transfer.
• weight - correction strength, 0–1, default 1. Full replacement at 1.0.
• blur_mode - box (A1111 original) is the default and gives an exact A1111 match. gaussian (smoother) exists because box blur's sharp frequency cutoff can produce patchy color artifacts when ColorFix runs without a tile ControlNet. If you're pairing this with a tile ControlNet (the usual setup), box is fine; standalone, try gaussian first.

Output is a single patched model - feed it to your KSampler instead of the raw one.

Install

Pure Python, no requirements.txt, no model downloads:

cd ComfyUI/custom_nodes
git clone https://github.com/ihorpankin/comfyui-colorfix-v3.git

Restart ComfyUI; it's under colorfix-v3. ComfyUI Manager: search "comfyui-colorfix-v3".

Where people get burned

Two things. First, this is a color lock, not a structure lock. In a tiled upscale the tile ControlNet (the pack's "Apply Ultimate ControlNet") keeps each tile faithful to the source; ColorFix keeps the colors consistent across tiles. People who run one without the other tend to blame the wrong node when tiles drift. Second, the patch is registered as a post-CFG sampler callback, so it does its work after CFG does its thing - if you're seeing color shift only on high-CFG renders, lower the CFG rather than fighting it here. And if you want detail enhancement on top of the color fix, the pack's +Sharp variant is the one that does that.