Do you have any old file format images?
I'm specifically looking for: OS/2 Metafile (.met) PICT (Mac's precursor to PDF) https://en.wikipedia.org/wiki/PICT
Also useful might be: PCD - Kodak Photo CD RAS - Sun Raster Image
I'm trying to evaluate if LibreOffice should keep support for them (specifically if the support is good). Unfortunately I can only generate the images using LibreOffice (or sister projects) which doesn't really provide a great test.
Please either: * Provide a link in a comment below * Email me B @ (If emailed, please mention if I can share the image publicly)
If I find the support works great I'd try to integrate a few of them into LO tests so we make sure they don't regress.
I know that the ffmpeg project has a huge set of sample images: https://samples.ffmpeg.org/image-samples/
Maybe this is of help to you,
Take a look at the File Formats wiki, they may have links to samples:
Please contribute to the wiki if you can.