🔧 USDU Edge Repair

Seams are the chronic disease of tiled upscaling. Each tile is an independent img2img pass, and where they meet, colors and contrast drift - you see a grid instead of an image. The USDU family already has seam-fix modes, but this node goes one step further: it builds a dedicated edge mask for the boundaries between tiles and feeds it back into the differential-diffusion pass, so tile edges get blended toward smoothness during sampling rather than patched afterwards.

The source layout says a lot - usdu_edge_repair is a self-contained subpackage with its own geometry module, preview module, and diffdiff module. The author is treating seam handling as its own engineering problem, and it shows in the interface: edge_mask_width (default 20px), edge_mask_feather (default 8px), and use_edge_mask_diffdiff (default False) - the switch that actually applies the edge mask to the diffdiff pass for smoother blending.

The workflow

It's a solver-driven (No Upscale) node: upscaled_image + output_width/output_height/tiles_x/tiles_y from the Smart Tile Solver, safe_guard validation, enable_diffdiff/enable_controlnet toggles, per-tile conditionings, sampler block, mode_type, tile size/padding/blur, standard seam-fix block, tiled_decode. Optional: denoise_mask, multiplier, model_patch, control_image, control_strength, control_mask.

Two things set it apart. First, preview_mode (default False) - flip it on and instead of a final image you get the intermediate tiles and masks out, which is how you debug where a seam is coming from. Second, the output array is the richest in the family: image, tiles_original, tiles_padded, tiles_blend_mask, tiles_edge_mask, tiles_processed, and debug_info. If a seam survives your current settings, tiles_edge_mask will show you whether the mask is actually covering the boundary.

Installing it

One of ~100 nodes in ComfyUI-ArchAi3d-Qwen by Amir Ferdos (ArchAi3d). ComfyUI Manager → search "ArchAi3d Qwen" → install → restart, or:

cd ComfyUI/custom_nodes
git clone https://github.com/amir84ferdos/ComfyUI-ArchAi3d-Qwen.git
cd ComfyUI-ArchAi3d-Qwen
pip install -r requirements.txt

Restart. Needs only ComfyUI's bundled torch/numpy/Pillow; the heavy deps in requirements.txt serve other pack nodes. Free for personal use; commercial use needs the paid license.

The traps

use_edge_mask_diffdiff defaults to False - the headline feature is off until you turn it on, so a first run without toggling it is just another Universal V2-class upscaler. And it inherits the family rules: solver values in, raw source out, safe_guard on during setup, conditioning count matching the tile count. Start with preview_mode on for a stubborn seam so you can see the edge mask before you spend a render trusting it.