🧩 Stitch Tile

Stitch Tile is the second half of a pair - it takes the tile images and geometry that Split Tile produced (after you've done whatever you wanted to each tile in between) and pastes them back into one complete image, blending the overlapping edges so the seams don't show.

This is the manual version of what tools like Tiled Diffusion and Ultimate SD Upscale do automatically inside a sampler: split into overlapping chunks, process, blend back. The community's whole reason for tiling in the first place is running a heavy operation - an upscale model, a detail pass, a ControlNet-guided resample - on a huge image without needing all of it in VRAM at once. Stitch Tile is the step that makes the result look like one image again instead of a grid of independently-processed rectangles.

How it works

Each tile arrives with its matching "stitcher," which records exactly where that tile sat in the original image. Stitch Tile pastes each tile back at its recorded position. Where blend is on, it feathers the transition across the overlap zone that Split Tile deliberately captured - so if two neighboring tiles came out with slightly different pixel values near their shared edge (which happens whenever you run a generative or resampling step per-tile), the transition is smooth instead of a hard visible line. With blend off, it's a plain hard paste - faster, but any per-tile difference near the seams will show.

Inputs and outputs

• tiles (IMAGE, required) - the tile images, ideally the same list Split Tile produced, possibly after your own processing step.
• stitchers (TILE_STITCHER, required) - the matching geometry list from Split Tile. Order has to line up with tiles.
• blend (BOOLEAN, default true) - whether to feather the overlap zones. Leave this on; turn it off only if you deliberately want to see the raw tile boundaries for debugging.
• image (IMAGE, single output) - the reassembled full image. Feed this into Save Image, Preview Image, or another Split Tile pass if you're doing multi-stage tiling.

Common issues

It only works if the tiles still match the stitcher geometry. If something between Split Tile and Stitch Tile resized or cropped the tiles differently than the stitcher expects - an upscale model that changes tile dimensions, say - the paste-back math can misalign. If you're upscaling per-tile, plan the tile sizes up front for your target output resolution rather than upscaling arbitrarily and hoping Stitch Tile compensates.

Order matters, not just content. Same caution as on the Split Tile side: tiles and stitchers are matched by list position, so any reordering or filtering has to be applied identically to both lists or you'll get tiles pasted in the wrong place.

There's not much documented beyond the README's one-line description for this pair, and it doesn't show up in general ComfyUI discussion the way Tiled Diffusion or Ultimate SD Upscale do - this looks like a niche, purpose-built primitive rather than a widely-discussed one. Test it on a small image with a visible grid pattern first so a misalignment is obvious before you run it on something you actually care about.