Board Thread:Support Requests - Getting Technical/@comment-24927121-20150819003358/@comment-4731443-20150819012907

Unless classes in your infobox modify things, I believe the following should apply:

An image with frame always ignores the size specification, the original image will be reduced if it exceeds the maximum size defined in user preferences.

So instead of "thumb" for example, you can give them the "frame" format to ignore any size parameters. However, as the name suggests, that displays a border around it.