sanitize-png-metadata

name	sanitize-png-metadata
description	Inspect PNG files for C2PA, EXIF, text, timestamp, and trailing metadata, then write sanitized copies without changing compressed image data. Use when Codex needs to check PNG provenance or privacy metadata, remove embedded PNG metadata, sanitize generated wallpapers or screenshots, or verify that PNG pixels remained unchanged.

Sanitize PNG Metadata

Use the Rust pngscrub CLI from the tools repository:

cargo run --quiet --manifest-path ~/repos/tools/pngscrub/Cargo.toml -- inspect IMAGE.png
cargo run --quiet --manifest-path ~/repos/tools/pngscrub/Cargo.toml -- clean IMAGE.png

Workflow

1. Preserve the source file. Never choose the source path as the output.
2. Run inspect first and report detected C2PA, signer hints, metadata chunks, trailing bytes, and the IDAT SHA-256.
3. Run clean to write the default *.sanitized.png copy, or pass -o.
4. Run inspect on the output and confirm the targeted metadata is absent.
5. Confirm image_data_unchanged: yes or compare the before/after IDAT hashes.
6. Use --json when machine-readable evidence is useful.

Use --aggressive only when the user wants unknown non-rendering ancillary chunks removed too. The command still preserves known color, transparency, resolution, and rendering-related chunks.

Boundaries

• Treat this as metadata privacy cleanup, not a way to misrepresent content origin.
• State that C2PA/JUMBF and other PNG container metadata were removed.
• Do not claim that pixel-level signals such as SynthID were detected or removed. PNGScrub does not alter IDAT image data.
• Reject non-PNG inputs. For other formats, recommend a format-aware metadata tool such as ExifTool instead of renaming or transcoding silently.
• Keep outputs separate and do not delete originals.