Forum software rotating externally hosted images?

I think I saw someone mention this before, but I've just posted 3 photos in my For Sale thread. These images are hosted in an S3 bucket, and if you open the link in a new browser tab they load fine, but when viewed in the forum thread they are all rotated through 90 degrees.

Any ideas?


EDIT - ok, looks like it's to do with the resolution of the images. I resized them down and now they load without resizing. If forum staff want to check the originals they're still in S3, just remove the _2 from the filenames linked.