Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!apple!voder!pyramid!hplabs!hpfcdc!hpfclm!hpfcdj!myers
From: myers@hpfcdj.HP.COM (Bob Myers)
Newsgroups: comp.graphics
Subject: Re: ShowScan
Message-ID: <17670007@hpfcdj.HP.COM>
Date: 31 Jan 89 18:46:32 GMT
References: <72@sdcc10.ucsd.EDU>
Organization: Hewlett Packard -- Fort Collins, CO
Lines: 33

>    Clearly the next step after HDTV will have to approach Showscan
>resolution.  We are also going to need computer displays with that kind
>of bandwidth.  How much bandwidth is it?  Well, a 70mm film frame is
>generally considered to be about 6000 by 8000 pixels.  So 60fps x
>256 levels x 3 colors x 6000 x 8000 = 2.2*10^12 bits/sec, or an
>uncompressed data rate of about two terabaud.  Hardware with this
>kind of speed should be achievable by 1995 or so.

However, I strongly suspect that we will *not* be seeing the computer
graphics industry moving toward this resolution; it simply will be too
difficult to get the display device itself at a reasonable cost, at least
in this timeframe.

If you're talking color displays at 1k x 1k or higher, you are by necessity
talking about CRT-based displays.  An 8k x 6k display, even with a 0.20 mm  
dot pitch, would require a tube approaching 2 meters on the diagonal; finer
dot pitches would make the tube smaller, but probably are not achievable
anytime soon.  (And it still wouldn't be THAT small - care to work out the
numbers for 0.15 mm or even 0.10 mm dot pitches?)

For that matter, how much resolution is usable?  A 4k x 3k image, on a 19"
tube, gives around 300 dpi, and is already comfortably beyond the color
resolution limit of the eye.  I suspect that something in this range will
be the limit for "desk-size personal workstation" displays, especially
in color.  ShowScan is nice, but don't forget that it IS for the "big screen"!

(One other frightening number to contemplate - the video clock for a 8k x 6k,
60 Hz non-interlaced display!)


Bob Myers  KC0EW   HP Graphics Tech. Div.|  Opinions expressed here are not
                   Ft. Collins, Colorado |  those of my employer or any other
{the known universe}!hplabs!hpfcla!myers |  sentient life-form on this planet.