Digital Signal Processing Reference
In-Depth Information
FIELD 0
ODD NUMBERED ROWS
FIELD 1
EVEN NUMBERED ROWS
ROW1
ROW2
=
VIDEO FRAME
30 frames/s
VIDEO fields
60 fields/s
Figure 6.1. Interlaced video.
Progressive scanning scans the entire video frame one line at
a time and each pixel value within that line is transmitted.
Modern monitors put video lines on one at a time in perfect
order
ROW 1, ROW 2, ROW 3, ROW 4, etc. Each frame is
updated every 1
e
=
30
th
of a second
or in other words 30 frames
are displayed each second, one after the other.
Our problem surfaces when an interlaced video has to be
displayed on a progressive screen. That's where deinterlacing
comes into play.
Today, deinterlacing is an important video processing
function and is required in many systems. Much video
content is available in the interlaced format and almost all of
the newer displays
e
LCD or plasma
require progressive
e
e
video input.
However, deinterlacing is by nature complex and no algorithm
produces a perfect progressive image. Let's look at some basic
deinterlacing techniques.
6.1 Basic Deinterlacing Techniques
Fundamentally, deinterlacing is the process of taking a stream
of interlaced frames and converting it to a stream of progressive
frames. One way to do this could be as simple as reversing the
Figure 6.1 to Figure 6.2
.
In this example we take the two fields and combine them to
create one frame. This rather simplistic deinterlacing tech-
nique is called “weave” deinterlacing since we are “weaving”
two fields to create a single frame. This technique works well
