I just downloaded a new little program / app from the app store called iSplash. It’s pretty much obvious what it does if you just look at this picture. It was originally shot in Savannah, Georgia, USA and was colored. The modification iSplash offers takes about 30 seconds. You can choose wether you want to take the colored picture and add grey parts or the other way around.

The colored parts are chosen like in Photoshop with a brush that can be changed size-wise and with that brush you just scroll over the areas you want to be colored. Pretty easy (this one took like 10 seconds) and the picture can be saved afterwards.

Nice tool if you like this effect and don’t want to bother with Photoshop.