[opendtv] Re: 20050509 Mark's Monday Memo

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Fri, 20 May 2005 07:48:09 -0400

At 12:09 PM -0500 5/19/05, Doug McDonald wrote:
>Craig Birkmaier wrote:
>>  What is important is not the source resolution but delivering a
>>  sharp, high quality picture to the average display.
>No, Craig, it's not to the AVERAGE display, it's to the BEST

You've got to be kidding.

This is a digital television system for the masses;  perhaps a whole 
lot more. But one thing it ain't is a play toy for videophiles and 
the folks who hang out at the AVS forum.

According to Hollywood, "The Best" is 4K x 2K on a gigantic screen. 
Is this what you are expecting from DTV?

Optimizing for "The Best" is an elusive target. With respect to the 
ATSC standard was it at its best in 1997?

In 2000?

In 2004?

Or will it be 2007?



Here's a big hint.

Every day that passes, the ATSC standard becomes less relevant. 
MPEG-2 is no longer "The Best" compression technology. 8-VSB never 
was "The Best" modulation technology.  And broadcasters are still 
doing "Their Best" to ignore the mandate to move to DTV, favoring 
instead to stay with "The Best" we could do half a century ago. NTSC 
is at it's best on a 19" screen viewed at seven picture heights.

Being the BEST is a continuously moving target. The trend-line is 
always UP, perhaps to counterbalance "Good Enough", which keeps 
trending down. Those who can afford "The Best" will always seek 
something better than what the average viewer expects. The truth is 
that today's off-the-shelf 65" HD capable displays deliver better 
picture quality than the videophile systems of a decade ago. Yet 
people are still spending six figures on state-of-the-art home 
theater systems, because they want "The Best."

By know you should understand that for DTV, big numbers DO NOT mean 
that something is "The Best."   There are too many variables in terms 
of original source quality and what happens to that source as is 
moves from creation to emission. And numerology, both in terms of 
acquisition and display rasters can be highly misleading. What 
matters is delivering a sharp picture on the screen at the designed 
viewing distance. Large displays that need more samples to deliver 
the HD experience can do so with proper re-sampling. We have a new 
generation of 1080@60P displays hitting the market, yet 1080@60P is 
not even a meaningful format for acquisition or emission today. What 
these displays need is high quality source to convert to 1080@60P - 
Good 720P will equal or exceed the quality of 1080i source on these 
displays in most cases. It is the integrity of the samples, not the 
number or samples that matter.

And just for the record, the average HD display size today is near 
the lower end of the range of screen sizes that are well served with 
720P.   The growing interest in LCD panels is likely to cause the 
average screen size to decrease rather than increase.

And one more thing. I was in Circuit City yesterday cruising the HD 
displays. If you were to ask people what size set had "The Best" 
picture quality, the answer would be the ones that are smaller than 
40 inch. Why? Because the demo loop was so poor that on the big 
screens you could see all kinds of compression garbage.

So be careful when you are asking for a system to be optimized for "The Best."

>720p is adequate for ANY size display if you sit far enough back!

DUH. A 13" NTSC set is as sharp as most HD displays.

You are a scientist Mr. McDonald. You understand basic math and 
physics. Therefore you should be able to figure out that there is a 
simple relationship between screen size, viewing distance and 
resolution requirements. Two things are important:

1. That you cannot see evidence of the raster (one of the best 
reasons to be rid of interlace).

2. That the display be capable of delivering details in the range of 
22-30 cycles per degree of the viewing field, which is what the human 
visual system needs for the perception of a sharp picture. Obviously 
good contrast and good MTF performance go hand in hand.

Do the math Mr. McDonald, and you will find that 720P is adequate for 
screens approaching 100" diagonal at a viewing distance of 3.3 
picture heights.

>I'd say that for most people 720p is great for 40 inch displays
>like I own, and OK at 60 inches. But at anyting over 50 inches,
>you really clearly will be happier with better .... unless
>the incoming sigal is fuzzy, of course.

Do the math.

By the way, the incoming signals are a big part of the problem. That 
"FUZZ" is trashed samples that have been over compressed.

You can UNSUBSCRIBE from the OpenDTV list in two ways:

- Using the UNSUBSCRIBE command in your user configuration settings at 

- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word 
unsubscribe in the subject line.

Other related posts: