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From: dhesi%cirrusl@oliveb.ATC.olivetti.com (Rahul Dhesi)
Newsgroups: comp.arch
Subject: Display resolution (was Re: Sun's Competitive Strategy)
Message-ID: <2788@cirrusl.UUCP>
Date: 9 Dec 90 01:05:14 GMT
References: <1990Nov16.225515.494@zoo.toronto.edu> <1990Nov25.194404.3376@dircon.uucp> <1635@unix386.Convergent.COM> <1990Dec2.014554.3491@Neon.Stanford.EDU> <2760@cirrusl.UUCP> <2764@cirrusl.UUCP> <76095@iuvax.cs.indiana.edu> <c82A02WA03kX01@JUTS.ccc.amd <1990Dec6.0
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Let's just clarify a few things here.  The crispness and detail visible
on a display (which is what the eye cares about) depends on three
things:  (a) the sharpness of the electron beam, (b) the number
of scan lines, and (c) the screen.

The electron beam must be sharp, and I mean "sharp" in both a static
and a dynamic sense.  In the static sense, the size of the electron
beam must be small when it hits the screen.  This is a function of how
well it's focussed.  In the dynamic sense, the brightness (modulation)
of the electron beam must vary quickly and precisely as it scans
horizontally.  This is a function of the video bandwidth.  The sharper
the electron beam, the better the resolution in the horizontal
direction.  The greater the number of scan lines, the better the
resolution in the horizontal direction.

The screen must respond properly to the video beam.  This is more
critical on a color display, in which case the smaller the dot pitch,
the better the sharpness of the screen.  Also, when the electron beam
hits the phosphor, the light generated scatters in many directions.  A
good screen phosphor suppresses excessive scatter, so the eye sees a
tiny point and not a fuzzy circle.

Once the beam hits the phosphor, the phosphor should remain lit for
long enough but not too long.  If it's lit for not long enough, you may
see flicker.  (This flicker can be suppressed by a higher vertical scan
rate.  Around 60 to 70 Hz is good, but 100 Hz is better.)  If it's lit
for too long, changing images will be mushy.

Claims like "1000 x 9000 resolution" have no meaning.  Claims like
"1000 x 9000 screen pixels" do have some meaning, but the meaning is
not necessarily related to resolution.  Ideally you need to specify
video bandwidth, number of pixels in both directions, and dot pitch.
--
Rahul Dhesi <dhesi%cirrusl@oliveb.ATC.olivetti.com>
UUCP:  oliveb!cirrusl!dhesi