[sane-devel] annoying bug in sp15c backend ?

[jazz_johnson at verizon.net]

On Wednesday 09 January 2008, m. allan noah wrote:
> my preference would be to help Rene extend the Avision backend to
> fully support these machines (or maybe break the avision backend into
> two- older and newer machines) and drop the sp15c backend from sane.
> you've used both backends, how much better is sp15c?

I'm aware that the avision backend exists, but I haven't really tried it. I 
don't know why I picked the sp15c backend, other than that I have a Fujitsu  
SP15C scanner and the sane model support page said that the (unmaintained) 
sp15c worked for this scanner and that the avision needed testing.

When I was looking to buy a scanner for (mostly document) scanning that would 
work with linux, the company from which we were purchasing our system had an 
SP15C for sale, so we bought it. For interactive scanning, I used xsane with 
the  sp15c backend. That frontend-backend combination worked, so when I 
needed to write a shell script for non-interactive batch processing, I used 
the option SANE_NAME_s from the sp15c backend. So I've stuck with it since it 
works with my shell scripts. I used those same SANE_NAME_s when I wrote the 
hs2p backend.

I remember looking at the sp15c and avision backend code when I was writing 
the hs2p, but I don't know how different they are from each other. From the 
users' perspective when they run xsane with either backend, these are the 
different controls presented by xsane:



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}
                                                             
Standard AVISION Options: 
--speed, --quality-scan, --quality-cal,  --power-save-time,
In addition to std xsane brightness/contrast controls there are also:
--brightness, --contrast, (not sure why)

Advanced AVISION Options:
   Geometry: --l,--t,--x,--y, 
   Enhancement: MessageLine

Standard SP15C Options:
   Geometry: --l,--t,--x,--y, 
    Enhancement: --threshold
Advanced SP15C Options:
   <NONE>


The Fujitsu ScanPartner 15C scans at 300x600 just fine with the SP15C backend 
(but it doesn't prevent you from scanning at 600x600 which results in a 
skewed image when the scanner returns half the expected bytes for each line)

For my hs2p backend I allowed independent x/y resolutions 
(--resolution, --y-resolution) of type SANE_Range, but also provided a new 
option --std-resolution {0,60,75,...800} to let the user choose from 
pre-selected standard resolutions (and update x/y resolutions accordingly)

---

Jeremy