Digital Signal Processing Reference
In-Depth Information
SCAN LINE DUPLICATION
SCAN LINE INTERPOLATION
Figure 6.5.
“
Bob
”
deinterlacing.
Bob deinterlacing provides good results when the image
intensity varies smoothly, but it can soften the image because it
also reduces the vertical resolution.
Both bob and weave deinterlacing can affect the image quality,
especially when there is motion. The bob method can soften the
image and the weave method can create jagged images or mouse
teeth artifacts.
Figure 6.4
contrasts an image generated with the
bob technique with one generated with the weave technique. An
obvious way to get better quality deinterlacing would be to mix up
both the techniques described in the preceding section, after
computing whether there is motion between successive frames of
video. This technique, which advocates the weave technique for
static regions and the bob technique for regions that exhibit
motion, is referred to as “motion-adaptive deinterlacing.”
6.2 Motion-Adaptive Deinterlacing: The
Basics
The key to motion-adaptive deinterlacing is to estimate
“motion”. This is the most computationally intensive task as it
assesses the differences of one field to another
and remember
there are 60 of these fields passing through in one second.
This is usually done by looking at a window of, for example,
e
3
3 on each field. Since field zero contains row one, skips row
two and contains row three, this means a 3
3 window will give
you two rows of three pixels each. In field one
since both rows
e
one and row three are skipped
you will only get row two with
e
three pixels (see
Figure 6.6
).
One way to understand motion adaptive deinterlacing is to
understand that you have two options to calculate the value of
a missing pixel:
