Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!olivea!uunet!mcsun!ukc!stl!crosfield!rak
From: rak@crosfield.co.uk (Richard Kirk)
Newsgroups: comp.graphics
Subject: Re: VT320 viewer
Message-ID: <10309@suns501.crosfield.co.uk>
Date: 18 Jun 91 09:26:46 GMT
Reply-To: rak@crosfield.co.uk (Richard Kirk)
Organization: Crosfield Electronics, Hemel Hempstead, United Kingdom.
Lines: 21

A couple of people asked me about my VT320 image viewer. I have trued to
send the program and the image set-up file through the post, but it hasn't
arrived. I'm not sure if any of the escape characters in the set-up file
are fouling things up. If the people concerned could send me their e-mail
address (I erased the original letters) I'll have another go.

I won't post the thing here as the escape sequences might do all sorts of
anti-social things. I'm also not very proud of the program, which was a quick
bodge to fit a need. But I can describe it...

VT320's in 132 character/line mode display 4 characters as a square.
With 65 grey levels from black to white, and dithering 4 characters gives
255 grey levels. I used only 51 grey levels as we commonly display %dots
from 25 (0%) to 225 (100%).

I reserved the control line 25 for input, and line 24 for reporting the line,
pixel, etc. This gave a 23 * 33 pixel display.

-- 
Richard Kirk    Image Processing Dept     Crosfield Electronics Ltd. U.K.
                0442-230000 x3361/3591    Hemel Hempstead, Herts, HP2 7RH