Pixel Perfect Checker — Detect Scale, Blur and Off-Grid Pixels
Is this sprite really 3× nearest, or 2.5× bilinear? The checker finds the columns and rows where colour changes and proves the block size from them — no sampling, no guess.
- PNG framesMeasured· Pillow
- PaletteMeasured· re-import
- pixel-lab.jsonUNVERIFIED
What it does
- Exact integer scale and offset from where colour changes happen (finds off-grid crops too).
- Non-integer scale estimated from the shortest runs only (a 2.5× nearest resize reads 2.500×).
- Blur detection: counts edge pixels whose colour lies between two neighbours, plus soft-alpha pixels.
- Recover the 1× source (only when an exact grid is proven), integer scaler 1×–8×, colour budget and silhouette check.
How to do it
- Drop the image.
- Read the report: scale, offset, blurred edges.
- If an exact grid was found, recover the 1× source; otherwise upscale by whole numbers.
- Export.
Outputs and how each was checked
"Measured" means the downloaded file was opened again outside the page (Pillow, numpy or an independent parser) and the property was measured. Loading these files in a game engine was not tested.
| Target | Files | Check |
|---|---|---|
| PNG frames | anim_N.png · 1×–8× nearest | Measured PillowEvery exported colour re-read from the PNGs lies inside the locked palette. |
| Palette | .gpl · .hex (Lospec) · .json | Measured re-importEach format was exported and imported back through the UI: 16 → 16 colours. |
| pixel-lab.json | generic frames + palette | UNVERIFIEDGeneric JSON; not loaded in any engine. |
Evidence
8 anti-aliased frames → one 16-colour palette with 0 exported colours outside it; an unchanged region identical in all 8 frames with dithering off and with Bayer 4×4; the anti-alias remover took 271 colours to 16 without moving a single silhouette pixel; integer scale, offset and 2.5× non-integer scaling detected exactly.
Limits
- Frames larger than 4096 × 4096 are refused: every pass runs on the main thread, and there is no cancel button yet.
- A sprite sheet is treated as one image; cut it into frames first (sprite sheet cutter).
- With a dithering mode on, the cleanup counts include dither pixels; set dithering to None first.
- The exported JSON is generic; importing it into Godot or Unity was not tested.
Questions
Why does it say "not confident"?
A one-colour image, or one that changes on only one axis, has no grid to measure. The checker says so instead of guessing.
Can it fix a blurry (bilinear) upscale?
It measures it — on the test sprite 1243 edge pixels (86.3 %) were in-between colours — but an exact recovery is only offered when a clean block grid exists.
Is it free, and do I need an account?
Everything on these pages is free and works without an account. There is no watermark and no export that is held back.
Are my sprites uploaded?
No. The Studio decodes, packs and exports in this browser tab. Projects are autosaved in the browser (IndexedDB) and can be saved as a .nerulio file.
Does it need Aseprite or an engine plugin installed?
No. .aseprite files are read and written in the browser, and each engine bundle carries what that engine needs (for Godot, the import settings and scene; for Unity and the Godot TileSet, a small editor script).