OR

sane-support for the canon pixma mp780 is fairly limited. Especially there is no supported mode for scanning greyscale or black/white. This is a tragedy cause most ipfax-solutions need b&w or at least a decent gray as input.

A lot of converting is done within ipfax-solutions including dithering, resizing in unpredictable order, so one needs to provide a good input or your fax will end up as grey clouds or convered with dots and/or lines or the beloved marks of unwanded dithering.

A good input has 300 or 600 dpi and is b/w only. Xsane cannot provide this with a pixma mp780. So you cant use the email-feature within xsane !!! Additionally dont use the pdf-output of xsane. It produces huge pdf-files with poor quality.

My solution here that gives satisfying while not perfect results :

1. use the multipage-scan-feature with 300DPI to scan all pages you need to fax
2. save the project as tiff-file
3. use convert from the imagemagick-package to convert it to a b&w-PDF :
   convert xsane-multipage.tiff -threshold 60% fax.pdf’
4. use your prefered mailapplication to send this fax.pdf to your ipfax-gateway

Notes on the threshold:

depending on the original different threshold-levels between 60% and 80% seems to give the best result. 60% will not give you the best result in any situation but it will produce a readable output in any situation.

I tried a lot of convert-variations and if you like to do so on your own, here are a few hints:

• -dither activates dithering. You need to specify the dither-method you want. I found out that dithering is extremely bad for faxing
• +dither seems to disable dithering, but I got better results by avoiding the word dither at all

Tips & Tricks

If you only need to convert a single page, you can specify the pagenumber like that:

convert source.pdf[0] -threshold 80% bw.pdf

this will only convert the first page