Shibiko AI - Waifu2X

Waifu2x was the anime upscaler before ESRGAN existed, and it's still one of the few upscalers that never invents anything. Where a SUPIR or SeedVR2 pass is generation - it will happily rebuild a face into a plausible different face - this node just makes the image bigger and cleaner. No diffusion, no hallucination risk, no 10GB VRAM appetite. It's a small CNN, trained on art (or photos), that does 2x or 4x upscaling plus noise removal in one pass. If the upscaling doc in the KB splits the world into "more pixels" versus "more detail," waifu2x is firmly in the first camp, with a side order of denoising thrown in.

This node is a port of Nagadomi's nunif waifu2x implementation - the same one the author credits in the README - and it's the thing that makes the pack worth grabbing for a lot of people. Community chatter about waifu2x stays alive but modest (roughly 60 mentions across r/comfyui and r/StableDiffusion in the last couple of years), which tracks: it's not trendy, it's just quietly correct.

How it works

The node loads the model through PyTorch Hub at runtime:

torch.hub.load('nagadomi/nunif:dev', 'waifu2x', model_type=model_type, ...).to('cuda')

That line is worth reading twice, because it means two real requirements: first run downloads the nunif code and the model weights from GitHub (you need internet once), and the model is moved .to('cuda'), so no GPU, no node. The noise_level and scale inputs combine into a mode - scale 1 means noise removal only, scale 2 gives noise_scale, scale 4 gives noise_scale4x. Batches are handled per-image and re-stacked, so a whole batch of frames goes through fine.

The inputs that matter

Three optional inputs, and honestly the defaults are decent:

• noise_level (0–3, default 3) - how aggressive the denoise is. Set it to 0 and raise scale if your source is clean; you're just upscaling.
• scale (1, 2, 4) - the multiplier. 4x from a small base is where this shines on anime/illustration.
• model_type (art / photo) - the art model is the famous one. The photo model exists and works, but for photographic sources modern generative upscalers usually beat it; this node earns its keep on drawn art.

The single output is an image you can wire straight into a VAE encode, a second-pass img2img, or a Save Image.

Install

Same story as every node in this pack:

cd ComfyUI/custom_nodes
git clone https://github.com/Shibiko-AI/ShibikoAI-ComfyUI-Tools

Or use ComfyUI Manager and search for "Shibiko". Restart ComfyUI. The pack's requirements.txt is light - colour-science and rembg - and waifu2x itself pulls in nothing extra beyond what PyTorch Hub fetches on first use.

Where people get burned

The first-run download is the classic stumble - it looks frozen while it's pulling the model from GitHub, so don't kill it. And remember this is a GPU node: on a CPU-only machine it dies at the .to('cuda') call before it ever runs. If you're on a photo workflow, temper expectations; if you're touching up anime art before a hires pass, this is the one you'll actually reach for.