http://www.digitalfilmtools.com/powermask/

Power Mask is the first realtime, interactive tool capable of extracting almost any object in an image--even if you are dealing with fine hair detail, smoke, or reflections. As you simply paint along the edge of the object to be extracted, either the mask or the final composite can be revealed instantly. This extraction process creates what is known as a mask--essentially a black and white cutout. White mask areas are extracted, black areas not, and gray areas in between represent a level of transparency. Once a mask is extracted, the foreground object can be seamlessly composed onto a new background in Adobe Photoshop as well as apply filter and image corrections only within the area defined by the mask.

To work this magic, Power Mask updates the mask or composite in realtime while you roughly paint a stroke along the boundary of the foreground object. Results show that compared with previous approaches, our method is more efficient and requires minimal effort to extract high quality masks for foregrounds with significant semi-transparent regions. In addition, the foreground edge colors are estimated in the semi-transparent areas to create a seamless composite. Realtime, interactive masking is now a reality with Power Mask.