AfterFocus by is a app which simulates the ability of DSLR and other high end camera's aperture settings to blur backgrounds. It is available for Android and iOS. Achieving this is simple enough. Once you select a picture to edit, you can select the item in the picture you want to keep in sharp focus, the background and even identify objects between the foreground and the background, allowing you to have three different levels of focus on the same image. Picture edited with after focus can be uploaded and shared on different photo hosting and social networking sites.
Here is a photo I edited with AfterFocus. On top is the original picture, and below is the modified picture.
I edited the picture in a phone with a 4.3-inch display outlining the foreground and background with my finger. Despite the large display my finger proved to be a bit large to outline the borders between foreground and background accurately. So while I achieved good results with the app, it would be much better with a device equipped with a stylus.
The App also has a feature called double photo, but I have not able to try this yet, as it is available only on the pro version of the app. The version of AfterFocus on the Android market is a free add supported version which does not included the double photo feature. The pro version will be out in the Android Market sometime in may according to the developer.