Hey Just download the tried out your plugin and I think it will work perfectly for my needs.
But on my dev local host version I found this notice I though I would let you know about.
Notice: image_resize is deprecated since version 3.5! Use wp_get_image_editor() instead. in /sites/wp-includes/functions.php on line 2824
Ofcourse the plugin still works but I just though I would pass it along. Thanks for dev'ing such a simple user friendly plugin.