What a great idea for an app. After you try on someone they love it and ask me to try it on their wife or friend. The Homer Simpson showed up perfectly for my brother-in-law. I would think that there is an opportunity for you to add in app purchases for certain theme x-rays like sports (golf, tennis, skiing, football etc.), beverages (martini glass, wine bottle, pint of Guinness etc) life style (A hammock between two palm trees, beach chair next to a palm tree etc.) . The result would have to be select-able by the user so it is appropriate for the friend being scanned. I would think that there is enough free themed clip art that you could convert to gray scale for your scans.
One operational thing, when I first downloaded the app the flash flickered on and off during the scan. I downloaded an update today and the flash action is gone. Could this be made select-able? I think it adds a little "authenticity" to the scan.