[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.
Regards
Craig
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