Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!crdgw1!control!kassover
From: kassover@control.crd.ge.com (David Kassover)
Newsgroups: comp.graphics
Subject: Re: HDTV
Keywords: HDTV/MIT
Message-ID: <5579@crdgw1.crd.ge.com>
Date: 27 Feb 90 00:13:51 GMT
References: <5461@bgsu-stu.UUCP> <1990Feb26.215623.9194@imax.com>
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In article <1990Feb26.215623.9194@imax.com> dave@imax.com (Dave Martindale) writes:
>In article <5461@bgsu-stu.UUCP> searcy@bgsu-stu.UUCP (todd Searcy) writes:
>
>There is a difference between NTSC and HDTV - if you sit close enough
>to the screen.
>
I, for one, am not surprised.  Long ago, in a galaxy far away, I
was doing my Master's work in a project that involved IBM 3277
Graphics Attachments.  They came in a variety of configurations,
but we had the 14 inch screens and the 19 inch screens.  The 19
inchers were wonderful, since what we mostly were dealing with
were stroke graphics back then.  You could turn out the lights
and kick back and get your work done without hunching, etc...
 
But the poor guys who had to work with projects that involved
what we now call bitmap images went nuts, since the 19 inch
screen had the same number of pixels  (oops, it's IBM, therefore
pels 8-) ) as the 14 inch.  In order for these images to lose
their perceived graininess, one had to move so far back that the
subtended angle of the 19" screen was LESS than that of the 14"
screen.
 
I also notice, as I walk past rows upon rows of televisions in
department stores that when I get far enough away from (most of)
the big screen jobs to be comfortable watching them, the images
are significantly crummier than comfortable viewing distance on
smaller, "standard" CRT displays.
 
The lesson I learned is that if you want to go significantly bigger, you have
to provide both more and smaller pixels to retain perceive image
quality.  There's also a thresholding effect wrt brightness and contrast.
 
I wonder if people in the pretty pictures graphics industry would
benefit from a couple of good technical photography courses,
where they go into the (mathematical) relationships between focal
length, frame size, intended viewing distance, aspect ratios, etc.