All you do is click the blue button that says "Upload Photo" and browse to a photo on your local computer (and select it). You'll then see that pic in the browser and the corners will be slightly rounded at the default corner radius of 50. Use the dropdown/slider to increase the radius as much as you want and you'll see the effects as you do it. Once you're happy, click the orange button for "Save Picture" and it'll let you specify where on your computer to put the modified version. It adds "_rounded_corners" to the filename so it won't overwrite your original, but you can change it if you want.
I find this very useful for cleaning up scans that don't show a playing card's corners as well as I would like.
Enjoy!
Donna
