Image files downloaded from Wikimedia sites do not contain any information about the images (author, license, description page URL etc). This makes it hard to identify the source or the author in certain context (e.g. image reused on the web without proper attribution); arguably it causes certain ways in which Wikimedia publishes these files (such image tarballs) to be license violations. The situation could be improved by embedding this information into the file as metadata (e.g. EXIF fields).
This is tricky as it would mean that the image needs to change on upload and potentially every time someone makes an edit to the file page; or we would have to make the original image hard to access and instead offer a modified version (a kind of full-size thumbnail - see T67383) for download/view/export.
* T2657 - using metadat in the opposite direction
* T20871 - the same issue for thumbnails
* T95217 - same issue for audio files
(Original reporter: `reflection`)