[opendtv] Re: Public M/H information

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Sat, 20 Dec 2008 08:02:00 -0500

At 6:07 PM -0500 12/19/08, Manfredi, Albert E wrote:
Since each visible cycle is represented by a dark and a light line, or
two pixels at least, you're saying that human visual acuity goes up to
about one arcminute, or 60 individual lines per degree. This is what
I've read elsewhere, for someone with 20/20 vision. A lower limit of
visual acuity sometimes quoted is 1.6 arcminutes.

It take 3 pixels (minimum) to create a line pair. In a television system it takes at least five because of the need for Nyquist filtering - black to white transitions are illegal.

TV is not about resolution - it is about the accurate portrayal of motion, without aliasing.

The nominal viewing distance for my iPhone is about five picture heights - I cannot see the raster on the 480 x 360 screen at this distance, even with reading glasses. Properly encoded video is VERY sharp - easily as good as my 50" HDTV at 5 picture heights.


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