[opendtv] Re: Spam Filter?
- From: "Cliff Benham" <cliff.benham@xxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 11 Jan 2005 10:03:23 -0500
The worst offending sources of interlace artifacts are the chrome=20
front grills in over-enhanced car commercials. When shot at a distance
portions of those grills occupy only one or two NTSC scan lines which =
makes
the interline twitter annoyingly excessive. The same can be said
for graphics with edges or characters that occupy only one or two lines.
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Craig Birkmaier
Sent: Monday, January 10, 2005 11:18 PM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Spam Filter?
At 10:13 AM -0500 1/10/05, John Golitsis wrote:
>To catch interlace artifacts, you'd have to be looking at a scene with
>motion.
Really?
I did an extensive tutorial on interlace artifacts at a SMPTE WInter=20
Technology Conference in 1995. Most of the imagery I used was stills,=20
created specifically to show how increased levels of detail cause=20
obnoxious artifacts on interlaced displays. Those fine details=20
typically DO NOT cause problems on progressive displays, but you=20
rarely get to see them because they "should be" filtered out before=20
NTSC compression.
As I have indicated in many previous posts, it is the undersampling=20
of images that causes the problems with de-interlacing. You are=20
asking a $20 chip to guess in real time about the samples that were=20
not acquired. I see many artifacts during dissolves to (or between)=20
still images.
So the reality is that there are interlace artifacts on interlaced=20
displays (and progressive displays if the source is not=20
de-interlaced); and there are undersampling artifacts when we attempt=20
to predict what the missing samples look like
Steve got it exactly right. We can solve the problem easily by=20
stopping the archaic practice of video undersampling.
Regards
Craig
=20
=20
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