How to create fax quality PDFs to save max space?

Report · Nov 20, 2021

I need to upload to my bank some 400 pages of images/scans turned into PDFs.

The bank has rules for <= 5MB, and <= 20 files.

I've converted the color profile to grayscale, but the file size is still too large when selecting just 30 files.

What additional settings in Acrobat Pro DC can I use to lower the file size even more.

The best decription of my goal I think is Fax quality.

Report · Nov 20, 2021

You should use something like Photoshop for that.

Report · Nov 20, 2021

Okay, a fax typically has 200 dpi and 2 colors (black/white). Shading is only created by dithering. You can print your PDF with the Adobe PDF printer as a new PDF but with the option "print as image" and a lower resolution. Then you can use the Preflight plugin and create a new fixup that will convert all colors to just black and white.

Therefore select the fixup menu (wrench button), click [Optionen] > [Create Fixup…].

Set the destination to "Black & White" and disable all other checkboxes.

When you then execute the fixup on you PDF you'll get the typical quality of a fax machine.

Report · Nov 22, 2021

Thank you. The Fixup is a great feature. It seems to give users easy access to many other features scattered in other places of the GUI (ie. color conversion).

I took ~300 diverse PDF documents and combined them into a file that was 90 MB.

I compressed, cropped and color converted to Grayscale down to 50 MB.

Then I tried your Fixup solution and achieved 19 MB.

This was a great improvement, and well within the ballpark for my needs.

For your own edification, here are some of the results:

1) This file was one of the few text-based PDFs in the group. I could save more space I if I managed these files better. Regardless, this shows what the dither does to perfect type.

2) Here is an invoice with copy-form gray type. It's legible.

3) Here is a handwritten copy form with gray-colored marks. Again, legible. But, it's funny how the "0" in 2020 was just blown out to that ghosted color.

Overall, these results are acceptable as a representation of the Original PDFs which are of course a representation of the Originals.

Thanks again.

Chris