[opendtv] Re: Spam Filter?
- From: Craig Birkmaier <craig@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Mon, 10 Jan 2005 23:17:41 -0500
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
Technology Conference in 1995. Most of the imagery I used was stills,
created specifically to show how increased levels of detail cause
obnoxious artifacts on interlaced displays. Those fine details
typically DO NOT cause problems on progressive displays, but you
rarely get to see them because they "should be" filtered out before
NTSC compression.
As I have indicated in many previous posts, it is the undersampling
of images that causes the problems with de-interlacing. You are
asking a $20 chip to guess in real time about the samples that were
not acquired. I see many artifacts during dissolves to (or between)
still images.
So the reality is that there are interlace artifacts on interlaced
displays (and progressive displays if the source is not
de-interlaced); and there are undersampling artifacts when we attempt
to predict what the missing samples look like
Steve got it exactly right. We can solve the problem easily by
stopping the archaic practice of video undersampling.
Regards
Craig
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