Table of Contents
Advertisement
Feature – 3:2 Pull down Process
There are two parts to the 3:2 Pull down feature. The first is the background, explaining
the 3:2 process that originated in the movie-film world. The second is the 3:2 pull down
process found as a TV feature.
Background
Movie producers still shoot with mechanical movie film at 24 frames per second. This
film must be converted to 60 frames or pictures per second for the TV / Video world. A
telecine process does this using the 3:2 pull down strategy.
Duplicating the movie frames increases the number of movie pictures from 24 to 60.
The first movie frame is duplicated three times. The second frame is duplicated two
times. The third frame is again duplicated 3 times, and the process repeats. Five
frames are shown below as an example.
Movie Frame
1
1
2
2
3
4
3
5
The duplication process is repeated until the 24 frames become 60 frames for TV.
Telecine process for movie-film to video conversion:
Duplicates each odd frame by 3 = 12x3 = 36 pictures
Duplicates each even frame by 2 = 12x2 = 24 pictures
TV feature - 3:2 pull down
Refer to figure 2. Normally a progressive scan TV combines two (odd + even)
interlaced pictures to produce a single progressive picture. After the telecine process,
an interlaced picture can consist of two different pictures. When they are merged in
progressive scan for a high-resolution image, different areas of the two pictures are
blurred.
1 field
Merged
even + odd
line fields =
Progressive
picture
Odd
line
Electronic pictures
1 field
Even
line
Figure 2 - Combining interlaced pictures
3
2
3
2
3
13 Pictures
from 5 movie frames
60 pictures from 24 movie frames
1 field
Odd
lines
2
Video
Picture
1 field
Blurred
Progressive
pix
(no 3:2 pull
down)
Even
line
Advertisement
Table of Contents
