[opendtv] Re: 1080i and 1080p are the same resolution
- From: Craig Birkmaier <craig@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Mon, 15 Oct 2012 08:22:11 -0400
At 7:44 PM -0500 10/14/12, Manfredi, Albert E wrote:
Peter Wilson wrote:
The number of pixels is only part of the story. The dynamic vertical
resolution is very different.
Look at a fashion catwalk with the model approaching the camera and watch
the detail in the costumes pump in and out as the model walks in a 1080I
production.
Good De-interlacing can make a big difference.
The author made two claims:
1. That the difference in quality is more a matter of frame rate,
not resolution.
2. That today's de-interlacers are amazingly good.
The first point I think, is valid and well demonstrated in his
article. In fact, the blurry background of the interlaced image is
exactly what you'd expect, with a 1/30th sec shutter speed as
opposed to 1/60th.
More likely the blurring is mostly just a depth of field issue.
What I don't know is to what extent broadcasters are limiting
vertical res these days, in DTV transmissions, to mitigate twitter.
Or whether they are counting on magical powers of modern day
de-interlacers, and not damaging vertical res at all?
You can be sure that they are still limiting vertical resolution, and
probably pre filtering to reduce artifacts. This is why 720P sports
broadcast usually look better than 1080i. Also most of the cameras in
use today use progressive imaging chips and then create either 1080i
or 720P. The 720P benefits from reduced entropy when the raw images
are resampled to 720P.
Regards
Craig
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