Very nice and intuitive! I have two feature requests/enhancements to submit though. 1. Ability to lock and/or save settings, so you could do multiple in a row (or come back to it later) without having to eye-ball the settings and 2. add layers, so I could add a device or mockup background and then use the top layer to transform the image to match the sizing dimensions and perspective. All-in-all, great work!
