What I'd do is scan them into Gimp and tweak them using the Colors >> Levels command to remove the bleed-through. I think 300 dpi is sufficient; anything over 450 would be overkill in this case.
With a quick check... ahhh. Gimp will let you export to a multipage PDF. It defaults to the first page being the bottom layer. On Tue, Sep 8, 2020 at 11:09 AM Andrea Croci <[email protected]> wrote: > > Hi Kelly, > > no, I'm not scanning text for OCR, I receive some documents per Mail > that I need to sign, scan and send back. When the document is printed on > both sides, the back side shows up if I don't adjust the brightness. I > haven't tried to process it in the PC, though. Maybe that works too. > > I would love to force the scanner to not auto-adjust, but I don't know > how to do that. Or how to force it to auto-adjust for that matter. All I > know is that with my Epson printer/scanner and the epkowa backend I have > a lot of options including adjusting the brightness. If I set that to a > value between 30 and 40 I don't get the back of the document to show > through. I would like to be able to do that in the new scanner as well. > > All I use Imagemagick for is the conversion of the huge .tiff out of the > scanner to a still big, but acceptable in most cases, .pdf. > > On 08.09.20 16:53, Kelly Price wrote: > > I take it you're scanning text for OCR? > > > > Consider it line art, and take some advice from Sean Michael Robinson > > in the Cerberus The Aardvark Restoration Project. > > http://momentofcerebus.blogspot.com/2017/02/paper-to-pixel-to-paper-again-part-five.html > > > > In short: > > > > * Scan in 24-bit color. It doesn't slow it down. > > * Set the brightness/saturation/contrast/gamma to the defaults, and > > don't touch 'em. > > * Force the scanner to not auto-adjust. > > * Your PC is better at adjusting the color values and forcing it to > > greyscale than the scanner is. > > > > To which I add: > > * ImageMagick and some shell scripting can bulk-process anything. > > > > > > On Tue, Sep 8, 2020 at 10:32 AM Andrea Croci <[email protected]> wrote: > >> Hi Alexander, > >> > >> thank you for your reply. That did work indeed: the scanner gets > >> recognised as 'airscan:e0:Canon MF745C/746C'. However the list of > >> options for that device is very short. For instance there is no > >> "brightness", which would be very helpful when scanning a page printed > >> on the backside too. That's what I always have to adjust with the Epson > >> scanner in order not to see the back printing through. > >> > >> In addition I just checked in my laptop, which has Ubuntu 20.04 > >> installed instead. That has recognised the scanner automatically with > >> the "escl" backend. I don't see an "escl.conf" in my desktop with 18.04. > >> Is this just a matter of sane-version? > >> > >> Is there any way to activate other functions for the scanner? > >> > >> Thank you and regards, > >> > >> Andrea > >> > >> On 08.09.20 12:30, Alexander Pevzner wrote: > >>> Hi Andrea, > >>> > >>> On 9/8/20 7:20 AM, Andrea Croci wrote: > >>>> I have just installed a new Canon iSensys MF746Cx on Ubuntu 18.04 and I > >>>> can't get it to scan. It' connected over the network. I haven't found > >>>> any driver or software for scanning on Canon's Website, so I was hoping > >>>> I could do it with sane. I have read on the list of supported devices > >>>> that the MF741/743 are fully supported by the pixma backend. > >>> The sane-airscan will probably work for you: > >>> > >>> https://github.com/alexpevzner/sane-airscan - the project page > >>> https://download.opensuse.org/repositories/home:/pzz/ - binary > >>> packages for many distros > >>> > > > -- Kelly "STrRedWolf" Price http://redwolf.ws
