This old question "Is EXIF data removed from uploaded SE pictures?" claims that

Imgur will strip the EXIF data once the image is uploaded to their server

Recently, a question posted on the new GenAI beta site demonstrated that:

The two frontends I'm aware of that store metadata in generated images do so in PNG text chunks, which are preserved so long as the image doesn't go over the limit where it gets JPEG'd

For reference, this is the image SirBenet posted there.

enter image description here

In this example, metadata about the used prompt is preserved.

It is therefore clear that multiple type of metadata exist and while some are removed when an image is uploaded some are not.

Based on my experience, I had also noticed that uploading an image in the chat interface does not work in the same way of uploading an image on the site: at the very best, some of the size limits are different between the two interfaces (I think that the chat ignores the 2 MB maximum size limit).

For this reason, I am asking the staff if they could confer with Imgur to confirm what is the actual current implementation and post the relevant information here.

  • 9
    I checked the metadata of those images and looks like they're using either an unnamed/anonymous tag or parameters tag. Perhaps these are not considered as standard Exif data and thus not stripped? Jul 20, 2023 at 8:09
  • 7
    PNG uses 4 character named chunks preceded by offsets to the next section. This allows custom sections to be easily added. EXIF data is well defined data stored in the eXIf chunk. It's likely that when Imgur says they remove eXIf, they mean it, and they don't touch anything else.
    – vandench
    Jul 20, 2023 at 14:48
  • 1
    Brief testing indicates that chat does enforce the 2MB max size limit, but may appear to not do so by allowing and accepting the upload, but Imgur converts the uploaded image to JPG and/or re-compresses the image to a smaller size. The GIFs which I uploaded in chat failed to upload when over 2MB. The JPG files I uploaded which were over 2MB were re-compressed to file sizes which I found to be well under 2MB when re-downloaded.
    – Makyen
    Jul 20, 2023 at 16:50
  • @Makyen I think there are two separate compression step, one on Stack side and one on Imgur side. Sometime ago someone said that chat may skip the compression on Stack side, but I really don't have any proof of that.
    – SPArcheon
    Jul 20, 2023 at 17:05


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