🐰 McBoaty Refiner - v6 /m

McBoaty is the reason most people install this pack. It's a tiled upscale-and-refine set built around a simple, proven idea from the hi-res-fix and tiled-diffusion lineage: slice the image, run a diffusion pass on each tile, blend it back - but tuned so aggressively for fidelity that the output is meant for printing. McBoaty Refiner is the node that actually does the per-tile KSampling. The name is a Boaty McBoatface joke; the work is serious.

It consumes the pipe that a McBoaty Configurator or Tiler produced, runs each tile through your model, and hands back the refined tiles plus a pipe you can feed into another Refiner pass. Where v5 packaged the whole upscaler+refiner into one giant node, v6 split it into building blocks: Configurator → Refiner(s) chained → Untiler.

How it works

Feed it a MC_BOATY_PIPE (pipe), which carries the image, model, clip, vae and sampler settings prepared upstream. The Refiner walks the tiles, KSample-runs each one with those settings, and returns new tiles plus canny edges (tiles - cannies output) for visual checking. The tiles_to_process string is the killer feature: leave it empty to process all tiles, or restrict to specific ones - comma lists (1,3,5) and ranges (2-4) both work, so you can do a full pass then a targeted second pass only on tiles that came out wrong. That's the McBoaty refinement loop: one pass over everything, eyeball the tiles, then re-refine just the offenders.

pipe_prompty lets you attach a per-tile prompt/denoise plan from the v6 TilePrompter node; without it, the general settings from the pipe apply everywhere. color_match_method (default none) re-matches the refined result to the source colors when you do want it - options come from Kijai's ColorMatch (mkl, hm, reinhard, mvgd, and chained variants).

The one setting that matters

Denoise. The README is blunt: 0.27–0.35 is the sweet spot for "refine, don't reinvent." The community thread that introduced McBoaty said the same thing in 2024 - "twice as fast as Ultimate Upscale, better quality, but be careful with the denoise: 25 to 35, you can use more but be prepared for seams and hallucinations." Push past ~0.5 and tiles start drifting from the source. Keep it low, and McBoaty genuinely is the best "make the image bigger without changing it" experience in the pack.

Installing it

ComfyUI Manager → search "MaraScott" → Install → restart. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/MaraScott/ComfyUI_MaraScott_Nodes

Then restart. No model downloads for McBoaty itself - it uses whatever checkpoint you wire in (SD1.5, SDXL, SD3 all tested). The pack's requirements are the heaviest part: opencv-python, numba, blend_modes, color-matcher, and the pinned transformers==4.37.2.

Common issues

One honest warning from the README itself: a banner at the top says "McBoaty v6 is broken" and asks for help. The bug was a state-leak where tiles from one flow bled into another after chaining runs - the author opened issue 187, then fixed it by switching from static class properties to globals. So if you're on v6 and see tiles from a previous run polluting the next one, that's the known issue (check you're updated past the fix). If you'd rather not gamble, v5's monolithic LargeRefiner still works and is what most of the pack's benchmark numbers were measured on. And for very large images, the tile-count warning is real: if tiles exceed the 16k cap, the Configurator tells you to raise tile/feather size rather than quietly dying.