[sane-devel] Vertical bands with Lexmark X1150

[stef]

Le Wednesday 15 September 2010 15:21:06 Andrew Ziem, vous avez écrit :
...
> 
> Hi Stef,
> 
> Sorry! I had to do two things to make the shading file
> 
> 1. I forgot to define DEEP_DEBUG :(
> 2. I ran the commented-out parts of your shell script. (Apparently the
> first time I was running the code that was installed with Fedora and
> not the code I compiled myself.)
> 
> I am attaching a .zip with the log and all the PNMs.  Also there is a
> PNG from Windows XP for comparison.
> 
> (The large, solid white area in the Disneyworld PNG I posted on the
> mailing list is where I removed a person for privacy reasons.)
> 
> 
> Andrew

	Hello,

	to compute shading correction to be apllied on scans, the backend first 
scan a white area before the glass. It seems that usable white lines are 
lesser than other similar models.  A short term fix is to try o shorten the 
numner of lines used. In lexmark_low.c around line 4940 change
  if (yoffset + (8 * 4) / regs[0x7a] < lines)
    lines = yoffset + (8 * 4) / regs[0x7a];

to
  if (yoffset + (8 * 2) / regs[0x7a] < lines)
    lines = yoffset + (8 * 2) / regs[0x7a];

	so we use only 2 lines (you could alos try with 3 lines). If it isn't 
enough we'll have to change calibration to scan backward to find a better 
white area.

Regards,
	Stef