AuditImage
Guides

Why metadata disappears

Messaging apps, screenshots, social platforms, online compressors, format conversion. A picture almost always loses its metadata in transit, and that does not mean anything is wrong with it.

Metadata belongs to the file, not to the pixels

EXIF, XMP and C2PA all live in container segments outside the image data. Any step that keeps only the pixels and re-encodes drops those segments. The longer the chain, the lower the odds of survival.

Steps that strip metadata

Messaging: WeChat, QQ, Telegram (outside "send as file"), WhatsApp all recompress and drop everything. WeChat's "original" option still removes GPS and most EXIF.

Social platforms: Weibo, Xiaohongshu, Douyin, X and Facebook re-encode on upload. Instagram and LinkedIn read C2PA and show a label, but a re-download does not necessarily keep the manifest.

Screenshots: a screenshot is screen pixels, unrelated to the original file, with no original metadata at all.

Online compressors and converters: TinyPNG, Squoosh and the like strip by default. Most WebP and AVIF converters do not carry C2PA across.

Re-saving in an image viewer: Windows Photos and macOS Preview keep some EXIF, may rewrite XMP, and usually lose C2PA.

"Copy image": copying from a browser or the ChatGPT web app gives you a decoded bitmap that is re-encoded on paste.

Steps that preserve it

  • Sending the file itself: cloud drives, email attachments, AirDrop, Telegram's "send as file".
  • Exports from Photoshop, Lightroom and similar, when you choose to keep metadata.
  • An explicit exiftool -tagsFromFile copy.

What no metadata tells you

Only that the picture went through at least one stripping step. It cannot distinguish:

  • a real photo forwarded through WeChat;
  • an AI image that was screenshotted;
  • a picture whose origin was deliberately scrubbed.

AuditImage's verdict for such files is "No usable metadata", and it says plainly that origin cannot be judged. Any tool that claims to "detect AI" in a picture with no metadata is using a pixel-level statistical model; that has nothing to do with metadata and its accuracy is a separate question.

If you need to prove origin

While you still have the original: keep it, not just the forwarded copy; export from a device or app that signs with C2PA; or at least record the original file's SHA-256. AuditImage's report page shows the uploaded file's SHA-256, which serves as a record that "this is what the file looked like at that moment".