[sane-devel] annoying bug in sp15c backend ?

[René Rebe]

Hi,

I never had a sp15c scanner, but I voted in the past to let
someone test the functionality and if all just works with the
Avision backend get rid of the duplicate sp15c backend
(same probably holds for the tamarack backend).

Regarding the concurency: This should not be a big voting point, as
the open, work, close behaviour of the Avision backend should be the
same as with most other SANE backends, if a device is used it is used
exclusively.

I also do not plan to make the Avision backend more complex as it
is optimizing for thruput and can optimize hadware re-programming
away and this assumes noone else tinkers with the scanner
behind the backends back. After all it's a driver, and there should
be only one driver instance messing with the device at a given time.
(e.g. look at the HAL vs. wodim / cdrecord issues).

> OPTION         |            SP15C                |            AVISION
> =================================
> --source                    ADF,FB                            NORMAL,ADF
> --mode                     Lineart,                            Lineart,
>                                   Halftone,                         Dithered,
>                                   4-bit Gray,
>                                   8-bit Gray,                      Gray,
>                                    Color                               Color
> --resolution     std {0,60,75,80,...600}     [0-300] SANE_Range
> --y-resolution  std {0,60,75,80,...600}

I can certainly add support for 4-bit Gray. When I saw the
4-bit protocol bit set on a Avision device I wondered more if it
was random firmware data than an actual feature :-)

Regarding the resolution: The Avision backend allows scanning
up to what the scanner returns as max. or optical resolution. That
is up to 5400 dpi of Avision based film scanners :-) There is certainly
something in the protocol bits set to make my driver think it can
only go up to 300.

If someone needs different y than x resolution it's on my list of
"nice to have things" to implement next and should be farily easy :-)

Yours,

-- 
  René Rebe - ExactCODE GmbH - Europe, Germany, Berlin
  Geschäftsführer: Susanne Klaus, René Rebe
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