The conversion of 2D video to 3D (also called 2D conversion to 3D stereo and stereo conversion) is the process of transforming 2D ("flat") film into 3D form, which in almost all cases is stereo, so it is the Process of creating images for each eye of a 2D image. Conversion from 2D to 3D adds the binocular disparity depth signal to digital images perceived by the brain, therefore, if done properly, greatly improving the immersion effect while watching stereo video compared to 2D video. However, to be successful, conversion must be done with sufficient precision and accuracy: the quality of the original 2D images should not deteriorate, and the disparity signal introduced should not contradict other signals used by the brain for depth perception. If done correctly and completely, the conversion produces stereo quality video similar to the "native" stereo video that is recorded in stereo and accurately adjusted and aligned in post-production. Two approaches to stereo conversion can be flexibly defined: semiautomatic quality conversion for cinema and high quality 3DTV, and low quality automatic conversion for cheap 3DTV, VOD and similar applications.
Importance and applicability
With the increase of movies released in 3D, 2D to 3D conversion has become more common. Most 3D stereo non-CGI superproducts are converted completely or at least partially to 2D images. Even Avatar contains several scenes shot in 2D and converted into stereo in post-production. The reasons for shooting in 2D rather than stereo are financial, technical and sometimes artistic:
• The stereo post-production workflow is much more complex and not as well-established as the 2D workflow, requiring more work and rendering.
• Professional stereoscopic platforms are much more expensive and bulky than regular monocular cameras. Some shots, particularly the action scenes, can only be fired with relatively small 2D cameras.
• Stereo cameras can introduce various mismatches in the stereo image (such as vertical parallax, tilt, color shift, reflections and reflections in different positions) that must be set to postproduction anyway because they ruin the 3D effect. This correction can sometimes have a complexity comparable to stereo conversion.
• Stereo cameras can reveal the practical effects used during shooting. For example, some scenes from the Lord of the Rings movie trilogy were filmed using forced perspective to allow two actors to appear to be different physical sizes. The same scene filmed in stereo would reveal that the actors were not at the same distance from the camera.
• By their very nature, stereo cameras have restrictions on how far the camera from the subject can be and still provide acceptable stereo separation. For example, the easiest way to film a scene on the side of a building could be to use camera equipment in front of a neighboring building, using a zoom lens. However, while the zoom lens would provide acceptable image quality, the stereo separation would be virtually zero over such a distance.
Even in the case of stereo shooting, conversion may often be necessary. In addition to the above-mentioned difficult-to-record scenes, there are situations where the mismatches in stereo views are too big to adjust, and it is easier to convert 2D to stereo by treating one of the views as the original 2D source.