Just install the following package "nautilus-image-converter" and you will be able to right click any image and convert the size and rotate it.

My only wish is that you could also convert the image type from say tiff to jpg etc...

This is an awesome/handy/feature and great tool to have.  This is one way where GNOME/Nautilus excel, the possibilities are endless to simplify and make simple/mundane tasks quicker and more efficient than ever.