Its a new trend in digital photography coming “shoot first and focus later”, the technology first introduced by Lytro in its light field camera (see at Amazon) after that Nokia introduced it re-focus app for windows phone, HTC also joined the force by announcing HTC M8 smartphone and finally google introduced “google camera app” the features DSLR type shallow depth of field and bokeh effects, however the app is currently limited to very high-end android OS based smart devices.
The app virtually simulate different aperture sizes to achieve desired bokeh effect, so theoretically now a smartphone can do everything for you just like a DSLR..
Download the app for your smartphone