[sane-devel] Canon DR-C225 II - black scan

[m. allan noah]

I have just pushed v59 of the canon_dr backend up to our git repo.
This is an updated version of the patch I shared previously. The
calibration values are currently hard-coded for the C225, so the
quality is poor. But, we can at least get duplex color scans now. I
expect grayscale scans will segfault until I do some more work.

allan

On Thu, Jul 30, 2020 at 4:57 PM m. allan noah <kitno455 at gmail.com> wrote:
>
> Marek et al-
>
> I've spent a couple evenings looking at all the various logs that I
> have for the C225, and have discovered that it does a different type
> of fine calibration from other models. So, I've worked up the attached
> patch, against the current sane-backends sources. The idea is to
> re-use some of the existing calibration code instead of writing a new
> version just for this scanner. I expect this may not work, and if it
> does, it will only give us poor quality images. But, it should be
> enough to validate that the issue is caused by calibration. You will
> need to apply this patch to sane-backends source, and
> rebuild/reinstall. I don't have access to any Canon scanners at this
> time, so I have only verified that this compiles, unfortunately.
>
> Let me know what you find out, or if you need help.
>
> allan
>
> On Thu, Jul 23, 2020 at 8:53 PM m. allan noah <kitno455 at gmail.com> wrote:
> >
> > Marek, I'm sorry it has taken me a month to reply, life is a little
> > 'different' these days :)
> >
> > So I have gone back through every email thread I have had about the
> > DR-C225, and do have a set of logs from the windows driver. I will
> > attempt to determine which bit of magic we are missing. It will take
> > me some time, as I am travelling now. If you do not hear from me soon,
> > please feel free to reach out. Also, if you want to study up on
> > rebuilding sane-backends from source in the meantime, we will need it.
> >
> > allan
> >
> > On Fri, Jun 26, 2020 at 4:33 PM Marek <mrupniew at tlen.pl> wrote:
> > >
> > > Dear developers,
> > > I wonder if you could help me with resolving a problem with Canon
> > > DR-C225 II scanner (canon_dr backend). The output scan is all black. In
> > > 2015 there was a thread on the predecessor of this scanner: DR-C225
> > > (without 'II'), which suffered from similar problem. Unfortunately that
> > > thread seems to be prematurely abandoned without solving the issue.
> > > I'm attaching a scanimage log for a page scanned in a grayscale mode (for
> > > the color mode the output scan is black as well).
> > > Best regards,
> > > Marek
> >
> >
> >
> > --
> > "well, I stand up next to a mountain- and I chop it down with the edge
> > of my hand"
>
>
>
> --
> "well, I stand up next to a mountain- and I chop it down with the edge
> of my hand"



-- 
"well, I stand up next to a mountain- and I chop it down with the edge
of my hand"