From: Tom Sobota (TSOBOTA@teleline.es)
Date: 02/07/00-06:05:20 AM Z
Hi,
A 11.35 6/2/00 +0000, ha escrito:
>When was the first digital image made?
>Was it rastor or vector? Who thought up the idea of rastor images?
The first synthetic images generated with oscilloscopes, such as Lissajous
figures were not 'digital' in any sense, since the scopes were driven by
analog circuits, i.e. voltages.
But using an oscilloscope as an output device for computers was a natural,
you only had to transform the digital output to analog and feed it to the
scope. The first graphics devices, project Whirlwind at MIT comes to mind,
were like this. I worked with such a modified scope on a DIGITAL PDP-12 in
1969. These devices were not raster nor vectorial: each point was written
separately under program control and all of them had to be refreshed
constantly. If the number of points was big enough, the image started to
flicker badly.
Later, at the beginning of the seventies, Tektronix came up with a very
successful idea: the 40xx line of displays were vectorial and the image,
once written, stayed written. These units had an internal, analog,
autorefresh circuitry. So bye bye to flicker and image of considerable
complexity could be generated. They had a simple graphics language and were
connected to the computer with a simple serial line. No graphics card
necessary! However, when you wanted to change a small portion of the image
on screen, you had to redraw it all and the erasing cicle lasted about a
second. Images in motion were not possible. These units were only monochrome.
In 1980 I worked with a 4014 that had also an electrostatic printer on
which uncountable works of digital 'art' were produced. Few, if any,
remain, luckily :-)
Raster units started to be seen at the end of the seventies or thereabout.
This is a TV-set-based idea which avoids flicker keeping the image in a
local memory. The feasibility of a large memory capable of storing big
color images is rather recent: the first affordable raster units I know of
were associated with the IBM PC, around 1982. They were lousy at that time,
but have come a long way since then.
Of course, the IBM 1403 printer I used for generating crude graphics on
paper in the sixties was also a raster technology ;-)
Tom
Tom Sobota
tsobota@teleline.es
Madrid, Espaņa
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