[opendtv] Re: Microsoft Exec: 1080p HDTV Is Meaningless

Generally I think of a line on the screen as represented by a sum of underlying basis functions which are completely determined by the value at the known sample points (say the result of doing a a big DCT).

But this interpretation means you also can make assumptions about the varying values between those points, with exact upscaling, etc. If the original image was Nyquist limited then those assumptions will even be correct, else not.

- Tom

Doug McDonald wrote: 
Tom Barry wrote:

Craig -

I'm still not sure why you single out non-nyquist filtered images as being a special problem for non-square pixels.

To me, the main problem with non-nyquist images is the values at the designated sample points are correct but there is an ambiguity about what the values are between those points.


There is no ambiguity. The sample points are essentially squares, (or rectangles), each of which is filled with the
designated color. Non-Nyquist images IN EFFECT assume infinite resolution, with each "pixel" a fully, perfectly,
resolved square.

If you think of it this way, you immediately see the problem
with rescaling. It only works correctly with up-scaling to
2, 3, 4, 5, .... times as many pixels in each direction.

Doug McDonald


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--
Tom Barry                           trbarry@xxxxxxxxxxx 
Now seeking new full time position as video software developer
Find my resume and video filters at www.trbarry.com


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