Digital Signal Processing Reference
In-Depth Information
PIXEL VALUE TO BE
CALCULATED
field 3
field 2
field 1
field 0
+
OPTION 2
=
AVERAGE OF
Figure 6.8. Option 2: use the average of the two pixels in the same
eld (one above and one below).
is between the calculated amount and the previous amount. This
additional computation is also called “motion bleed” because the
motion values from more than one frame in the past are carried
over. It is an exponential decay; after a motion, it may take 3 to 10
frames before the weave is again stabilized.
Of course all manner of algorithms can be applied and all of
these algorithms
as long as they use a concept of estimated
e
motion
would be labeled “motion adaptive deinterlacing”.
e
6.3 Logic Requirements
The bob deinterlacing method with a scan-line duplication
algorithm is the simplest and cheapest in terms of logic. Output
frames are produced by simply repeating every line in the current
field twice. If the output frame rate used is the same as the input
frame rate, then half of the input fields are discarded because only
the current field is used.
The bob deinterlacing method with a scan-line interpolation
algorithm has a slightly higher logic cost than bob with scan-line
duplication, but offers significantly better quality. Output frames
are produced by filling in the missing lines from the current field
with the linear interpolation of the lines above and below. At the
top of an F1 field or the bottom of an F0 field where only one line
is available, that line is just duplicated. Again, if the output frame
rate used is the same as the input frame rate, then half of the
input fields are discarded because only the current field is used.
The weave deinterlacing method creates an output frame by
filling all of the missing lines in the current field with lines from
the previous field. This option gives good results for still parts of
an image but unpleasant artifacts in moving parts. The weave
algorithm requires external memory to store the fields.
