Image Processing Reference
In-Depth Information
35 mm format
Imaging area
37.72 mm x 20.4 mm
Note action safe area
Figure 4-7 VistaVision film dimensions.
Refer to Appendix D for a summary of the image sizes and nominal bit rates for
uncompressed digitized footage.
Semi-Professional and News-gathering Formats
Before portable video cameras were available at a size, cost, and performance that was
suitable for news-gathering, reportage took place with 16mm cameras and the film stock
had to be physically taken to a lab and then converted with a telecine system. This intro-
duced enormous delays in getting the content to air.
A lot of this original footage has probably been lost over the years, but with more
restoration work being done and the gradual opening of archives, some of this material
may still come to light and require processing through a video-compression system.
All the issues covered already with cinematic film apply here with the additional
consideration that the imaging rectangle of 16mm film is smaller. The consequence is that
the pixel size of the images is smaller and the relative grain size is effectively twice that of
35mm film. The results you get from 35mm will therefore be much better than 16mm.
Figure 4-8 shows the 16mm film format. Note the optical audio track. There is a vari-
ety of audio formats for 16- and 35mm film, and extracting the audio is quite a different
challenge from dealing with the image frames. This audio track is run continuously
through the projector while the images are pulled through the gate one frame at a time.
The audio is offset by some distance from the frame to which it should be synchro-
nized. This is necessary because the sound pickup cannot be mounted adjacent to the film
gate. If it were, the sound would suffer from the non-linear way that the film is pulled
through the gate. The solution is to offset the audio and allow a loop of film in the projector
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