Basically, you can place yourself in front of a blue or green wall, and using your iPhone, iPad or iPod touch, mix in a photo of, say, a volcano behind you. Then, all your Facebook friends will think you’re some sort of world adventurer.
But there’s a couple of catches: Kromath 3 only works on still photos so far, although the company says it’s working on a video version. Also, you’d better be pretty serious about your chromakeying, because this little app will set you back $35 at the App Store [iTunes link].
That price places this app directly in the crosshairs of professional photographers and directors who would like to visualize their fancy chromakey effects while in the field. The software gives them real-time tweaking tools for experimentation, such as a “garbage matte” that lets them select certain areas that will be (or will not be) enhanced by the chromakey effect.
In the picture below, you can see that the area immediately around the model is selected for the chromakey effect. Everything outside that selected area will be replaced by the background photo:
from: http://mashable.com/2011/02/25/iphone-app-creates-sophisticated-chromakey-effects-pics/