[opendtv] Re: Is this Apple's iTV?
- From: Craig Birkmaier <craig@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Sat, 17 Mar 2012 10:52:43 -0400
At 3:00 PM -0500 3/16/12, Manfredi, Albert E wrote:
Cliff Benham wrote:
OK, what percentage of 1080p or higher resolution programming from
all sources and transmission schemes is actually available to
consumers to watch at home in the world today? What I mean is how
much 1080p is actually getting to the inputs on my HDTV?
Cliff, I had a couple of reactions to this better than 1080p
resolution of the new iPad.
One reaction was the same as yours. The other reaction was, watch
Craig gush all over this, in spite of the fact that he poo-poohed
HDTV from day 1.
Not a fair representation Bert. I poo-poohed the ATSC standard, the
continued use of Interlace and the notion that everyone would be
required to buy a receiver that most would not use. And I poo-poohed
the notion that HDTV would protect broadcasting from the relentless
assault of Moore's Law.
The fact that we are now talking about true 1080P displays and the
streaming of 1080P content is more than adequate vindication...
The reason I didn't comment was that here is Craig's likely
response: "It doesn't matter whether the source material is 1080p or
better. You still gain image quality by oversampling the image to
the higher resolution."
There are two issues at play here Bert, and they are both related to
sampling theory.
Video is Nyquist limited - it must be filtered properly to display
smooth motion without aliasing. As a result, the video resolution
that can be delivered to any progressive display will necessarily be
half or less of what the display can deliver in terms of Non-Nyquist
filtered imagery. AND, since the digital delivery system is based on
entropy coding techniques (digital video compression), the actual
resolution of the source may be much lower than the theoretical,
especially when the channel bandwidth is constrained.
Thus, as I have stated many times before, you may get a higher
quality image on the display by upscaling a lower resolution version
of content where the samples are not compromised, than a higher
resolution version where the samples have been trashed by too much
compression.
Bottom line, the resolution of the display is only one factor in
delivered image quality, but a higher resolution display can do a
very good job of presenting ANY source by upscaling.
Now for the more important issue.
Most of what we view in our browsers and APPs is NOT Nyquist limited.
The samples are addressed directly - you can place black pixels next
to white pixels...
I have been using a retina display for more than a year - on my
iPhone. The ability to render very fine details with high contrast
has been a breakthrough for the content I view the most on this
screen.
Consider this. The Desktop Publishing revolution was driven by the
ability to use a relatively low resolution representation of a page
(~ 72 DPI) to create and proof a printed page. You could even print
out this representation on the best computer printers of the day - a
dot matrix printer. Then the Laserwriter changed the landscape; you
could print out a much higher resolution version of the page (300
DPI). The quality was nearly as good as professional printing, with
crisp text and graphics WITHOUT visible aliasing. OR you could output
to a digital pre-press system at resolutions up to 2500 DPI.
What the retina display does is deliver near laser printer quality to
the screen, with very high contrast ratios. Text looks as good as a
printed book; photos look like high quality prints. And the color
gamut is wider than that used for HDTV formats; this means better
color saturation and a wider range of colors.
I went to Best Buy yesterday to look at the new iPAD. It does for a
tablet exactly what the retina display did for the iPhone. This is
one of the best displays I have ever seen. And the extra pixels
(relative to HDTV) play an important role. The 4/3 or 3/4 screen
aspect ratio (remember you can rotate the tablet to view in portrait
or landscape mode) is friendly to all kinds of content, especially
web pages, books and photos. And the high resolution makes watching
letterboxed HD very enjoyable (or you can zoom to fill the screen).
I suppose that tablets are held up to viewing distances more or less
like those of HDTV sets, in terms of picture height viewing
distance. So, there's probably some rationale for HDTV quality
images, at best. IMO, much better than that is wasted. But if Apple
does it, I suppose we all genuflect and Believe.
In the '90s we talked about viewing distance for different
applications. Computers were up close and personal - 15 to 30 inch
viewing distance. TVs were for couch potatoes - generally 7-9 feet
minimum viewing distance. It was widely believed that people would
not watch TV on their computers sitting in an office chair.
The table as a "second screen" changes the dynamics. There was a very
important reason that when Apple introduced the iPAD, Steve was
sitting in an easy chair. The table can be used as a lean back device
for media consumption, game playing etc. One of the most popular
viewing venues for the iPAD is in bed.
The fact that the iPAD screen is a good HDTV screen at the nominal
viewing distance is important; but the fact that it is ALSO able to
deliver stunning imagery for other applications is equally important,
if not more so...
Think about the impact of a doctor making rounds and pulling up high
resolution medical images on that 264 DPI screen...
Regards
Craig
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