Very Computer

A few friends and I are working on this electronic design project, and I
am hoping that somebody can lend me a hand.

We are trying to simulate a fax transmitter/receiver by:

1. scanning in an image via a video camera
2. encode the image using some algorithm
3. transmit the data serially (maybe via modem) to somewhere else
4. decode the image
5. display the image on some output device

and I am not sure what kind of encoding/decoding algorithm is available
and what I should be considering. I think fax machines use a Huffman
encoding? Also, I've heard about a CCITT encoding scheme for graphics.

I am wondering if anybody know where to find sources detailing these
algorithms and/or if anybody could recommend some other algorithm.
The image is most likely black and white (maybe grayscale)...

Thanks in advance!

Jack Fu
MIT '96

Hope this helps!

Delft, 20 april 1995

Try the pbmtools package by Jeff Poskanzer. It has encoding / decoding code
for the g3-compression scheme employed by fax.

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 W. Schildbach    University of Regensburg, Germany
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: Try the pbmtools package by Jeff Poskanzer. It has encoding / decoding code
: for the g3-compression scheme employed by fax.

If you have photorealistic images and you want good compression, the JPEG
format would be a good choice. Look around in comp.graphics for the JPEG FAQ
which explains what it does and where to get it.
The programs are usually called CJPEG and DJPEG.

If you want really good compression and time is not a problem, try Fractal
Compression (from Iterated Systems). It takes about a minute on a DX2-66 for
a 640x480 color image - but the final size is 20K-25 without any noticable
degradation.
Contact me for their address - I've got their package for windows.

Andreas

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 Andreas Schiffler  Institute of Space and Atmospheric Studies (ISAS),
                    University of Saskatchewan, Saskatoon, Canada
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