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Rediscovering Compuserve RLE graphics

mbbrutman

Associate Cat Herder
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Before GIFs in 1987 the most popular "online" graphics standard was RLE, which allowed for 256x192 pixel black and white images that were safe to transfer over 7 bit dial-up links. Compuserve used RLE for things like weather maps, but users also contributed their own art. A lot of this leaked out to BBS systems, where the better images were passed around.

wave.gif einstein.gif


I have my own set of RLEs that I downloaded or created during the summer of 1987. Recently I decided to add RLE support to mTCP Telnet so that it could draw the images right in the program. Given how scarce these images are and how little information is available about them I decided to start by properly documenting them first. And then that led to me writing a new program to convert JPGs to RLE, a DOS program you can run in DOSBox to view RLEs and a simple "RLE" server so that you can experience it for yourself when using the new Telnet client. (If you have CBTerm for a C64 available and can connect to it through a serial to Telnet adapter then that should work too.)

See http://www.brutman.com/RLE/RLE_Graphics.html for details about the format and http://www.brutman.com/mTCP/mTCP_Telnet.html for the mTCP Telnet client that directly supports RLEs.

(For those of you who can't use mTCP directly, check out the two minute video. It gives you a quick walk-through of connecting and viewing an image through Telnet. Don't miss the easter egg at the end.)
 
I recall the windows 3.1 startup graphic was stored in a file with an RLE extension. Is that a more modern version?

I remember using cshow and converting gifs to rle and then using copy with /b switch to create a new win.com with my own logo, if it was less than 64K when it was done.
 
Those are probably not the same thing.

Windows color bitmaps used run length encoding for compression, but they are not the same as Compuserve RLEs. Compuserve RLEs are black and white only, and use an ESC sequence to signal the need for graphics. (Windows bitmaps would have no need for that.)
 
Anything that could do black and white graphics would be able to display these; they were not Color Computer specific. VIDTEX I think ran on Atari computers. CBTerm supported RLE directly, and was for C64s. And of course IBM compatibles were displaying these too.

Color for these is an accident of the display device; the image standard itself is just black and white.
 
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