Digital Signal Processing Reference
In-Depth Information
field 3
field 2
field 1
field 0
Figure 6.6. Motion-adaptive deinterlacing.
Option 1 is to use the pixel value from the following field
i.e.
e
weave deinterlacing. This is illustrated in
Figure 6.7
.
Option 2 is to use the average of the two pixels in the same
field
one above it and one below it or bob deinterlacing
(scan line interpolation). This is illustrated in
Figure 6.8
.
Of course, if there is absolutely no motion, one should go with
option 1, but if there is “infinite” motion, field 1 is incompatible
and option 2 should be selected. In reality there is always some
motion (never infinite)
e
so we reach for a compromise.
But first let's calculate motion:
Weave the fields to create two frames as shown in Figure 6.9.
Calculate the sum of the nine pixels
e
e
pixels are normally rep-
resented by 20 to 30 bits.
Take the difference between S0 and S1. This is M
the
/
motion value for this window.
Use the value of M to determine how much you would veer
towards option 1 or option 2. The simplest strategy would be to
weigh option 1 heavily if M is small and option 2 heavily if M is
large i.e. output pixel
(Option 1 value)
(1
M)
(Option 2
¼
þ
value)
(M).
The motion value calculated can be used as is or compared to
the previous motion value generated. If the previous motion
value is higher, then the current motion value is adjusted so that it
PIXEL VALUE TO BE
CALCULATED
field 3
field 2
field 1
field 0
OPTION 1
=
Figure 6.7. Option 1: use the pixel value from the following
eld.
