Was aware that it existed, but didn’t really bother with it before. There’s a tool called jpegtran which allows you to do lossless rotations and cropping of JPEGs. Very useful. Install package is libjpeg-turbo-progs, command usage is as simple as jpegtran -perfect -optimize -progressive -rotate 90 -outfile JPEGTRAN/JT02457.JPG DSC02457.JPG.