[sane-devel] Q: improving epson2 for Epson 12000XL
paddy-hack at member.fsf.org
Sun Sep 27 08:57:49 BST 2020
Sorry for not chiming in earlier.
I have been involved with development of the third-party epkowa and
utsushi backends for many years. A lot of the protocol is documented in
the code for the utsushi backend via doxygen source comments. See
# I guess I could add a job to publish the documentation in a more
# accessible format via GitLab Pages. Please submit an issue if you
# would like that.
Remaining comments inlined.
Wolfram Sang writes:
>> a) The scanner reports level "B8". For "B8", allowed brightness levels are in
>> the -4..3 range. However, my scanner returns -EINVAL for -4. To avoid that,
>> I guess I need to check the model name and adapt the range accordingly?
Only the following values are documented* -3, -2, -1, 1, 2, 3.
Yes, 0 is not documented as far as I know.
> Fixed with !529.
>> b) It seems to me that set_focus is not working for this model because
>> e2_set_extended_scanning_parameters() says "/* XXX focus */" and no byte in
>> the buffer is filled with the focus value. Probably the location is unknown?
>> And I'd need to snoop Windows USB traffic to (hopefully) figure it out?
There is no documented position that I know of but there is still space
where it might be set.
> Fixed with !530.
>> c) 'focus' has only two options. 0mm and 2.5mm. The hex values are 0x19 apart.
>> That being dec 25, it is tempting to try inbetween values. But I assume I'd
>> need some evidence that those values are "officially OK" somehow?
There are two documented values: 0xff for autofocus and 0x40 for setting
it to the glass plate. Other values appear to be allowed.
> This and also autofocus added with !531. If someone has comments, I am
> honestly looking forward to hear them. I am still new to the project.
I'll have a look at the merge requests and comment there.
> The only question left for me now: Should focus/autofocus settings
> really have CAP_ADVANCED?
That's debatable indeed but I'd say CAP_ADVANCED is appropriate for most
Hope this helps,
Olaf Meeuwissen, LPIC-2 FSF Associate Member since 2004-01-27
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