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

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

> I realized what the problem is - the OCR program needs the images (be
> they TIFF or whatever) to be in at least 200 dpi and many faxes come in
> at 150 dpi; of course I can't stop people from sending faxes at 150

Faxes are by default at 98 x 196 dpi (assymetric) and at 196 x 196
in fine mode.  They are never anywhere near 150 and never as high as 200.

> dpi.  Of course the error messages did not even hint that that was the
> problem. (stupid windows program).

> However, does anyone know of a (linux) utility to increase dpi of
> images?  Perhaps I could have faxrcvd process it with that before
> sending?  Thanks for your advice!

The problem is not Linux specific as any such tools should not do 
anything that is not a generic Unix, or even win32 console mode,
operation.

Convert to pbm, use pnmscale, convert back to TIFF.  This assumes that
there is no simple option on say tiffcp.

You will not add information and if the OCR package is a cheap or 
free one, it may well not be able to cope with the poor quality
of a fax image, especially if it was scanned.