# PNG to WebP sample study

Tested October 14, 2026 in the desktop Codex in-app browser. Synthetic inputs are original CC0 artwork, generated using Pillow 11.3.0. Six default-quality downloads were saved from the previous live tool and repeated byte for byte in the updated tool. The three settings on three inputs produce twelve distinct recorded output samples in total.

1. Download a paired PNG and WebP from https://filepetal.com/png-to-webp/.
2. Select the PNG in the tool, use quality92 (or the -q60/-q100 setting for that variant), convert, inspect and save the offered WebP.
3. Compare dimensions, bytes, frame count and SHA-256 with output-verification.json. Windows PowerShell: Get-FileHash -Algorithm SHA256 -LiteralPath '.\flat-checks.webp'. Browser encoders may produce different bytes; a hash mismatch alone is not proof of bad appearance.
4. Run `python generate-fixtures.py` with Pillow11.3.0 to recreate nine input PNGs in generated-png-fixtures; compare input-manifest.json. The malformed inputs are intentional. Do not use them as normal images.
5. Run `python inspect-webp.py flat-checks.webp alpha-bands-q100.webp animated-marker.webp` to independently parse RIFF chunks and decode the actual downloads.

Inputs include two-frame APNG, partially transparent bands, thin red/blue lines, few-color checks, a procedurally generated scene and nonprivate metadata. This is not an exhaustive codec, color-profile, phone or operating-system study. The new page adds preview and quality choice; existing resize limits and rejection boundaries remain. No exclusive competitor feature advantage was established.