[mythtv-users] Graphics card recomendation
stefan thomasson
stefan.thomasson at home.se
Thu Aug 31 14:06:26 UTC 2006
> -----Original Message-----
> From: mythtv-users-bounces at mythtv.org
> [mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Michael T. Dean
> Sent: den 31 augusti 2006 03:00
> To: Discussion about mythtv
> Subject: Re: [mythtv-users] Graphics card recomendation
>
>
> 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).
>
Could it be that you are thinking of the
Nyquist-Shannon sampling theorem?
http://en.wikipedia.org/wiki/Nyquist-Shannon_sampling_theorem
Not sure if that it should be used as you have described it though,
assuming we are speaking of a broadcast stream.
Your statement above would imply that a 256x100 would be more
fully represented (better quality) on a 768x300 than on a 256x300.
> 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.
That is the problem, you cannot take more samples, only interpolate new
values.
What you are describing above is a 2:1 mapping.
>
> 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).
Aren't they doing the opposite? More samples to create fewer dots?
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