Remember at CES when all of the companies were like “We’ll convert your 2D to 3D?” Yeah, ummm, nah. What will happen is that studios will back-convert some of their old movies – or movies not shot in 3D – to 3D using a time-consuming, partially automated process. Like in love, the first cut is the deepest:
The first step is to separate the shot into somewhere between two and eight layers of depth. Take, for example, an image of a man standing in front of a brick wall, with a blue sky behind the wall. The graphic artist might separate the shot into three layers: the man, the wall, and the sky. Then, he would take each layer and draw contour lines around any object that appeared there. He’d start by marking depth lines on the man using a computer, turning the image into a sort of topographical map. He’d repeat the process for any objects in the other layers. (If there were a bird in the sky, he’d draw lines there, too.)
This creates layers that the computer can then ‘tween based on surround frames. If the spot where a character was before is visible later, the computer can approximately assess what should be “behind” the character. While it sounds more like the Turner-ization of black and white movies (you have to be pretty old to remember that golden period in television), it’s the only way you’re going to be able to see Shaft in 3D.
Read more about it at Slate.