Re: flexfax: Viewing received faxes via http browser

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

> 
> First, the ".tif" extension on received extensions is extremely confusing.
> It is worth modifying the faxrcvd to use the extension ".fax" instead.

They are TIFF files.

> Second, users must have a tool capable of viewing either delivered
> Postscript files or the raw tiffg3 files. I recommend "faxview" at
> ftp://ftp.sgi.com/sgi/fax/contrib/ for UNIX based X servers.

For Widows NT 4.0, the imaging tool that is bundled will display
the group 3 encoded TIFF files from Hylafax.  With the junk fax I tried
it on, it showed the correct aspect ratio++, although it is possible that
the junk faxer used fine mode.

> An alternative approach would be to translate the tiffg3 files into a
> set of plain tiff files, one per page, and let people view *those*. This
> is left as an exercise for the CGI programmer....

cp is a good utility for this; tiffg3 files *are* TIFF files, although not
all TIFF files are tiffg3.  The problem is that people don't realise that
TIFF is a way of supplying parameters for multiple graphical file formats,
rather more than a graphic format itself.  It can code for raw bit maps,
LZW palletised images (similar to GIF), images coded according to group 3
fax rules, and, I think, even JPEG encoded images.  Unless, by plain
TIFF, you mean the uncompressed bit map with square pixels, you need to
specify what is allowed in your definition of plain tiff.

++ Checking the TIFF spec, it appears that XResolution (0x7x) and YResolution
(0x82) are mandatory tags, so a viewer should always have the information
to correct the aspect ratio, for a valid file, although I can't quickly
check that the files are valid.