[sane-devel] Vertical bands with Lexmark X1150

[Andrew Ziem]

On Sun, Sep 19, 2010 at 10:09 PM, stef <stef.dev at free.fr> wrote:
> 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.

I'm still seeing the bands with 2 and 3.  Should I send the logs again?

Andrew