1. Video format conversion
[??]

2. Format conversions
size change
frame rate conversion
(de)interlacing

3. Size change
Normally treated as a problem of image resizing; each image is processed separately

4. Interlaced signal
Similar to a spatial quinqunx…

5. Interlaced signal
Similarly, the spectrum of a quinqunx is this:

6. Interlaced signal
Ideal deinterlacing:

7. Deinterlacing
In the areas without motion, the ideal process is temporal interpolation
Where there is motion, I can interpolate spatially
Or, better (but more difficult), to use motion compensated temporal interpolation (see later)

8. Deinterlacing
A video-temporal (VT) interpolation filter would theoretically solve the problem, if the signal were bandlimited prior to interlacing

9. Deinterlacing
Example of edge-dependent interpolation:
con

10. Deinterlacing
Example of VT median filter

11. Deinterlacing
Better: motion compensated temporal interpolation

12. Frame rate conversion From film (24 fps) to TV (PAL/Secam)
- the film is accelerated (24 -> 25 fps) and each image is shown twice -> 50 fps
Not in the USA (60 field/s ,actually 29.97x2)-> telecine
- 12 field are added every 24 frame -> 60 fps:
2-3 pull-down:
- the film is slowed (24 -> )
- the third B is often omitted in DVDs
(its equal to the 1st): 480i24 format,
and the DVD adds it on-the-fly
- similarly, 3-2 pull-down:
AAABBCCCDD

13. Frame rate conversion
... and if we need to return to progressive, 60fps: two ways
Weaving takes two successive interlaced fields and reinterleaves them to create a progressive frame
- works well
- if the original material was progressive, like a film that has undergone the 2:3-pulldown process, and
- provided the disc tells the player that it was.
Bobbing, the normal process for generating a progressive signal from interlaced video, takes a single field and creates a full progressive frame from it by line doubling or line interpolation

14. Frame rate conversion
If the original material was interlaced video, not 2:3-pulldown film, weaving can cause artifacts
More advanced progressive-scan conversion systems combine bobbing and weaving, depending on the content (motion…) of the image.
If the monitor is 72 Hz: simply AAABBBCCCDDD…

15. Scan rate doubling Field repetition: te*=to to*=te
Gives loss of resolution
Frame repetition
te*=te
to*=to
generates artifacts if motion is present