Re: flexfax: Automated FAX to GIF or JPEG?

[David Woolley <david@djwhome.demon.co.uk>]

> 
> Does anybody have a good and public domain/free way to convert from fax
> format into either JPEG or GIF automatically, without losing

JPEG is a totally inappropriate format for faxes.  They are the exact opposite
of the continuous tone images that JPEG handles well.  (However, as someone
suggested a lack of tools for the GIF to JPEG step, I would point out that
the reference implementation of JPEG (cjpeg) does this on many more platforms
than just Unix.)

> significant quality (via using fax2ps and then converting from

If you are losing quality at any step except the JPEG step, you either have
broken tools, or are trying to change the resolution; I suppose it is 
possible that fax2ps tries to re-image for 300 dpi but I would have thought
it would leave that to the printer.

The netpbm approach seems the most likely one to me.

> 	   tifftopnm - to convert each TIF file to PNM
> 
> 	   However, there is no way to convert from pnm to GIF ot JPEG.

The reason for this is patents, although the copy of the netpbm tools
I have certainly can do this (I think all that is necessary, for free software,
is that the program was written before the LZW amnesty cut off date).
Note that the current generation of browsers should be able to cope with
png, the LZ 77 (zip) equivalent of GIF, which was developed when Unisys
started enforcing the patent.  They should all work with .xbm, but that
is a bit big.

> 	2) Then I've looked at tools such as "cjpeg" (as found in the
> 	   "xv" software), but these tools don't accept tiff or fax

cjpeg is part of the reference implementation of JPEG, not of xv.

> 	4) If you use "fax2ps" and then convert from PostScript to jpeg
> 	    or gif, then the quality of the FAX is significantly
> 	    worse than using "faxview/snapshot/xv".

If you use JPEG, that is inevitable - it is the wrong format for fax.
For GIF, try -r200x200 in the ghostscript options.   However, using
Postscript as an intermediate is a long way round.