[sane-devel] Lexmark experimental backend

[Fred Odendaal]

Stéphane,

I tested it on my Lexmark X1185.

It is broken really badly. It hangs in the function 
sanei_lexmark_x1100_search_home_fwd - infinite read loop in a poll after 
trying to move the scan head. I did a register compare from usb dumps of 
a good scan (sane-backends-1.0.17) and a bad scan (experimental) and 
none of the lexmark register defaults are set! There are 35 registers 
that used to have non-zero default values and now have 0x00 and one 
register that was 0x01 and is now 0x81.

Fred


Stéphane VOLTZ wrote:
> 	Hello,
>
> 	I have just committed a new version of the experimental/lexmark backend. From 
> the current regular backend it brings:
>
> 	- arbitrary scanarea selection
> 	- gain calibration
> 	- offset calibration
> 	- software shading calibration
> 	- Dell A920 support
> 	- infrastructure for adding more models
>
> 	I believe the experimental is in good shape to get into regular CVS. However, 
> while I took care of not altering X1100 support, and since I don't have such 
> a model to test, there may be bugs for this model. So it needs testing.
> 	For A920 1200 dpi scan is disabled, since it does 1200x600, and so needs 
> to "inflate" lines to match 1200x1200. Which is a little tricky since the 
> data copying expects even/odd columns interleaved.
> 	Last issue is shading calibration. This scanner has no hardware shading 
> calibration, and it has to be done in software. The current correction 
> implementation gives good results, but shows deficiency in dark areas. The 
> trouble is due to the fact that correction depends of the sensor element that 
> corresponds to the scanned column, but also slightly depends on his 
> neighbours in a way I couldn't figure out. Someone more clever than me will 
> have to find it.
> 	Pictures given "out of the box" are correct, and with little tweaking of 
> gamma and light from the frontend, one can have good scans.
>
> Regards,
> 	Stef
>
>