Image Processing Reference
In-Depth Information
remove the interlacing from your content, because if it is already in a progressive format
then this step is unnecessary.
Take into account the eventual picture size you are aiming for when select-
ing a de-interlacing technique.
This step is sometimes called interlace removal or de-interlacing. The user interface
on your compression software might use both terms interchangeably.
Interlaced video contributes a large amount of horizontal detail to your video and
makes the encoder spend all of its effort on compressing this artifact instead of the image
that you want to compress.
If you are using an MPEG-1 encoder, you must de-interlace first. The later encoders
generally support interlaced content internally. They may de-interlace in order to do this,
but you don't have to care.
Figure 33-1 shows a ball moving across the screen that moves a significant distance
between one field interval and the next.
If we zoom in close enough to see the interlacing effects, the two fields look like this
when they are viewed at the same time (as they would be on a progressively scanned
Removing interlaced artifacts (see Figure 33-2) will become more important in the
future because TV display is moving rapidly toward a progressively scanned presentation.
In addition to up-converting standard-definition video to high-definition, it must be
changed from interlaced to progressively scanned content.
Position in first field
Position in second field
shown in dashed outline
Figure 33-1 Rapidly moving ball.
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