[mythtv-users] Graphics card recomendation

Matthias Thyroff lists at Thyroff.net
Thu Aug 31 07:29:31 UTC 2006

Am Wed, 30 Aug 2006 20:59:46 -0400
schrieb "Michael T. Dean" <mtdean at thirdcontact.com>:

> On 08/28/06 08:35, Steven Adeff wrote:
> >  On 8/28/06, Dylan Semler <dylan.semler at gmail.com> wrote:
> >
> > > On 8/27/06, Steven Adeff <adeffs.mythtv at gmail.com> wrote:
> > >
> > >> On 8/27/06, Dylan Semler <dylan.semler at gmail.com> wrote:
> > >>
> > >>> My highest ambitions would have me try to take the two monitors
> > >>> apart, perhaps do a little machining, and try to rig it up so
> > >>> it looks like one very big and very wide monitor. Though, I
> > >>> guess the chances that this is even possible are very, very,
> > >>> very small.
> > >>>
> > >> just get a bigger monitor/HDTV.
> > >>
> > > I haven't looked extensively, but it seems that any monitors that
> > > I would find of the 2200x1200 genre would be prohibitively
> > > expensive.
> > >
> >  But you don't need that resolution for Myth... at most you could
> > use 1920x1080(1080p).
> >
> Or, really somewhere around 3840x2160 would be an appropriate output 
> resolution for a 1080i/p input resolution...  In addition to the fact 
> that (as previously mentioned by Daniel) 3840x2160 is an integral 
> multiple of both 1280x720 and 1920x1080, sampling theory
> (specifically, the reconstruction theory part of it) says that an
> output resolution must be greater than an input resolution to fully
> represent the detail in the image.  As a general rule of thumb, the
> output resolution needs to be at least 2x the number of pixels on
> each axis (i.e. 4x the pixels of the input signal).
> Yes, I know I took a lot of heat last time I said this, but last time
> I was on the road for a few weeks and didn't have the time to "prove
> it," so I eventually just let it drop.  In fact, the truth is, I'm
> not smart enough to prove it, but I do ask that before anyone writes
> back with messages saying, "How can you need more than 1920x1080
> pixels to display a 1920x1080 image?" or "Well, actually, if you
> upscale the image, you're just 'inventing' new information, meaning
> it [adversely affects picture quality|displays a made-up image, not
> the captured image]," that they read some of the many, many good
> books on sampling theory and reconstruction theory.  Instead, if you
> feel you must disagree with me and don't feel like reading up on
> reconstruction theory, just write me off as some crazy guy who
> shouldn't be given e-mail access.  (Oh, and make sure you post all
> sorts of messages about how crazy the marketing guys must think we
> are when they start trying to sell 3840x2160 displays even though
> ATSC defines a maximum resolution of 1920x1080.  I always enjoy a
> good rant--especially one with an "inside joke.")
> Boiled down to basics, there's a difference between image pixels
> (which are truly "picture elements"--samples of a picture at a point
> (of zero size)) and display "pixels" (which are really "dots"--that
> have a physical area).  The picture elements are created by sampling
> a continuously-defined image function, and, although you can display
> an image by painting pixels of the same value and at the same
> positions used to generate the picture elements (i.e. "1:1 pixel
> mapping"), you can create a much better image by recreating the image
> function and taking more samples at different positions and
> incorporating the additional information about the image function
> into the final display pixel values.
> Oh, and, of course, dots aren't "just" dots.  Each display pixel's 
> brightness can vary in intensity across its "surface" (i.e. as on a 
> CRT).  And, display pixels can vary in intensity across the display 
> (i.e. having a directionality as on an LCD).  And...  But, that's a 
> whole different argument.
> Unfortunately, there aren't many good sources on the 'net.  Why?  Who 
> knows?  Perhaps computer programmers are too smart to be fooled by
> all those complex mathematical formulae.  Fortunately, though, the
> ideas have been incorporated into the algorithms we use everyday (in 
> image-processing libraries, in printers/printer drivers, and even in 
> graphics hardware).
> Mike
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this is really interesting; I have not studied signal theory, I do
not want to write you off and I certainly appreciate if you continue
contributing to this list;-)

But, I wonder: where in your signal path do you have a continous
signal? Do you get 1080i/p tv programs on an analogue channel in the US?
In that case, I would go with you regarding the double resolution
requirement. But if it is DVB Stream - Myth - DVI - Display (all
digital), hm... 

I also believe you need a 3840x2160 digital camera if you
want to convert the 1080p real life monitor image to digital again
and reproduce all detail. 

But there are a lot of engineers for communications science
here on the list; maybe somebody actually can explain this to us?

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