It's all down to the power of liquid crystal displays, or LCD. Just like the liquid crystal in a watch can be changed from transparent to black, the lenses of PC 3-D glasses can be transparent or opaque. In other words, the glasses can control which eye sees the image on the screen, and with careful timing you've got perfect 3-D. Here's how it happens:
- The images are prepared by the computer and displayed.
Two images are generated, representing the views seen by each eye:
Both of these views are presented on the screen in rapid sequence:
- While the left view is presented, the right eye is blocked by the LCD glasses. Similarly, when the right view is presented, the left eye is blocked.
All of this happens so quickly that the brain is entirely unaware of the two images merging together into a stereoscopic view. This is the same thing as when we watch a film using an old film projector and the sequence of still images flickering onto the screen merges together to form a movie.