Re: flexfax: Viewing received faxes via http browser

[Nico Garcia <raoul@cirl.meei.harvard.edu>]

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On Sat, 25 Oct 1997, David Woolley wrote:

> > 
> > 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.

Fair enough. But many TIFF viewers can't handle them properly: for that
practical reason, it makes sense to differentiate them and call for a
distinct tiffg3 capable viewer.

> > 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.

Does it? *GOOD*. Does it have a name, or is it part of a specific
suite of tools? A pointer to that would be good to include with any NT
usage notes, and might function for Win95 installations (for
web-browsed faxes, for example).

The Win95 tools I'd tried and the UNIX tools had problems: some
insisted on translating it to Postscript to view it correctly (ghostscript),
others lost the multi-page information, others severely scrunched the
images, etc. I don't assume the tools did it correctly, I assume
that Sam Leffler did it correctly in writing HylaFAX: but it still
makes viewing faxes awkward.

> > 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.

Since that is (I believe) what most TIFF viewers know how to handle, this
is what I meant.

> ++ 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.

Thanks. I lack the expertise and time to dive into the TIFF specs, and
vastly appreciate your insights on this.

			Nico Garcia
			Engineer, CIRL 
			Mass. Eye and Ear Infirmary
			raoul@cirl.meei.harvard.edu

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