[sane-devel] genesys backend

[Henning Meier-Geinitz]

Hi,

On Sun, Nov 20, 2005 at 12:17:30AM +0100, Pierre Willenbrock wrote:
> after some e-mail exchange and bug-hunting with Stéphane the genesys
> backend should now support gl646 and gl841 based scanners.
> The Canon LiDE 35/40/50 scanners are now supported in cvs.

Thanks for all your work!
As far as I know, you use a LiDE 35. So i marked this scanner's
support as "good". If you think the level of support is different,
please change it in genesys.desc.

I tested a Canon LiDE 50. To get it running, I had to uncomment its
id in genesys.conf. I changed this in CVS. I Also changed the name of
the scanners to also show the Canon LiDE 40. Also I used a build
number of 7, because the last one in CVS was already 6.

The test results for my Canon Lide 50:

Generelly: Sometimes I have a dark vertical stripe near the left
border (about 1 cm width, over the complete image). This happens in
Preview but very seldomly. Also I have vertical stripes, especially in
medium-bright areas.

Color: 
75: Works, images are a bit too bright (over-imposed). Black
looks grayish and some brighter colors are nearly white.

150: Sometimes works, most of the time the scan hangs at about 95%.
I.e. there is a normal scan but the scan head stops and xsane never
displays the image. Also tested with scanimage. When it works, the
image looks like at 75 dpi. The problem depends on image width. E.g.
at a width of 20 mm, it always works at 150 dpi but not with the full
width. Sledomly, I also get a segmentation fault.

The log shows that this part is repeated endlessly in case of a freeze:
[genesys] genesys_read_ordered_data: using filters: reorder
[genesys] genesys_read_ordered_data: frontend requested 32768 bytes
[genesys] genesys_read_ordered_data: bytes_to_read=6814665,
total_bytes_read=6803082
[genesys] genesys_read_ordered_data: 3 lines left by output
[genesys] genesys_read_ordered_data: 3 lines left by input
[genesys] genesys_fill_read_buffer: start
[genesys] genesys_fill_read_buffer: reading 7723 bytes
[genesys] genesys_fill_read_buffer: failed to read 7723 bytes (Invalid
argument)
[genesys] genesys_read_ordered_data: reordering 0 lines
[genesys] genesys_read_ordered_data: completed, 0 bytes read
[genesys] sane_read: start
[genesys] genesys_read_ordered_data
[genesys] genesys_read_ordered_data: dumping current_setup:
        pixels: 1287
        lines: 1765
        depth: 8
        channels: 3
        exposure_time: 5276
        xres: 150
        yres: 150
        half_ccd: yes
        stagger: 0
        max_shift: 0

After the freeze or segmentation fault, the scanner is sometimes not found
anymore. Replugging fixes that.

300, 600 dpi: Works (overimposed) in full width. Doesn't work at e.g. width
100 mm (see above).

1200 dpi: Doesn't work in full width (see above). Works at e.g. a
width of 20 mm. This is much darker and has vertical stripes
(calibration problem?)

2400 dpi: Same as 1200 dpi. In addition, the image is too long (factor
2). I.e., in modes like 1200x2400 dpi the x resolution must be
"inflated" by either just duplicating pixels or, better yet,
interpolating them.

Gray:
75 dpi: Works, but is over-imposed.
150-600: see color
1200, 2400: see color 1200/2400

Lineart: similar to gray

I also did a spot check on color 16 bit and this seems to be less
over-imposed.

For now, I mark the support of this scanner as "minimal".
I marked the Canon LiDE 40 as "Untested". Can somebody please test
this scanner?

Thanks again,

Henning