Re: flexfax: TIF format used by hylafax ... <?>

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

> We use an OCR program to convert incoming faxes to text ... for some
> reason this program cannot read all of the files which hylafax creates
> (but it does read some of them).  This seems random.
> 
> I know the program only reads class 2-4 TIFF files; is this compatible
                                ^^^^^^^^^^
I don't think there is any such thing! (but might copy of the TIFF
spec is too deeply buried to check quickly).

Something you need to realise about TIFF is that it is a framework for
communicating parameters about images, rather more than a method for
communicating images.  As such, the syntax of the parameters block
is well defined, but the image content can be in many formats.

> with Hylafax?  The man pages say Hylafax puts them in TIFF Class F
> group3; am I out of luck?  Can I change the TIFF format Hylafax puts the
> files in?

I believe the author of Hylafax was involved in the specification
of TIFF; he may even have been a prime mover.

I would expect any OCR program to cope with fax coded (i.e. classs F)
TIFF files, but maybe not all of the suboptions.  However, there are
tools as part of the TIFF package, which is a pre-requesite for Hylafax,
that will convert between different TIFF subtypes.