[sane-devel] Plustek issues (Re: error messages from add-apt-repository sane-release)

[Perry Hutchison]

Ralph Little <skelband at gmail.com!skelband> wrote:
> On Fri, May 21, 2021 at 2:57 PM Perry Hutchison <pluto at agora.rdrop.com>
> wrote:
> > However this time it did add a file to /etc/apt/sources.list.d:
> >
> > $ ll /etc/apt/sources.list.d
> > total 12
> > drwxr-xr-x 2 root root 4096 May 21 14:08 ./
> > drwxr-xr-x 7 root root 4096 May 21 10:42 ../
> > -rw-r--r-- 1 root root  154 May 21 14:09
> > sane-project-ubuntu-sane-release-bionic.list
> >
> > $ cat /etc/apt/sources.list.d/sane-*
> > deb http://ppa.launchpad.net/sane-project/sane-release/ubuntu bionic main
> > # deb-src http://ppa.launchpad.net/sane-project/sane-release/ubuntu
> > bionic main
> >
> > Does this mean that it worked, despite the error messages?
> >
>
> Yes, it looks like you have two entries though. This one looks weird:
>
> Err:9 https://launchpad.net/~sane-project/+archive/ubuntu/sane-release
> bionic Release
>   404  Not Found [IP: 91.189.89.223 443]

I was able to clean that up using the configuration mechanism in
Software Updater, and got sane updated.  I now get:

$ scanimage --version
scanimage (sane-backends) 1.0.32; backend version 1.0.32

$ scanimage -L
device `pixma:MF4800_192.168.0.10' is a CANON Canon i-SENSYS MF4800 Series multi-function peripheral
device `gt68xx:libusb:005:003' is a Plustek OpticSlim M12 flatbed scanner

The Canon seems to work properly (as it did using the original
version of sane).  The Plustek partly works, but I haven't been
able to get "good" results:

* Using SimpleScan, the parts that should be black come out as gray,
  even with contrast set to maximum and brightness set as dark as
  possible.  (The white parts are correct.)

* Hoping to get rid of the gray, I tried:
  $ scanimage -d gt68xx:libusb:005:003 --mode=Lineart
  and got a blank (all white) image.

How would I go about finding a scanimage command that passes the
same backend settings as SimpleScan is using, as a starting point?