[sane-devel] Canon LiDE 90

[Pierre Willenbrock]

Guillaume Gastebois schrieb:
> Hello,
> 
> Selon Pierre Willenbrock <pierre at pirsoft.dnsalias.org>:
> 
>> Hi,
>>
>> Guillaume Gastebois schrieb:
>>> Hello,
>>>
>>> So, what's the next step ? Re-enabling shading ?
>> Yes, but only after the shading-calibration is able to get black level
>> information.(This really needs a better api..)
> 
> How to do that ? Do you mean a better api adapted to lide 90 or for all genesys
> backend ? Do you have some code ?

It is not as bad as i initially thought, the functions for receiving
black/white level information for shading are already available. But
there is some code duplication between genesys.c and
genesys_gl841.c/genesys_gl646.c. All three need to gather black/white
level information, for the various calibrations.

>>> Do you think that last modification "for (i = 150; i..." is necessary ?
>> Yes. Some time back, that part of the code just used the middle half of
>> the scan, exactly to drop the dummy black pixels at the begin. That
>> didn't work too well, missing some low black levels.
>>
>>> Is it time to fine tune registers 52... ?
>> Try increasing register 53, 55, 57 by one. Attached is a small program,
>> that shows the probability of any two-byte pair appearing in a file. It
>> takes the file as input and dumps an portable anymap(pnm) as output.
>> I created that program for something completely unrelated, but it proved
>> useful.
>>
>> I used it on offset1_1.pnm(as offset1_0.pnm is only black).
>> The image should show a fuzzy vertical and horizontal bar, near
>> top/left. Currently, the horizontal bar is more a line, the vertical bar
>> is correct(it shows the relationship between the low byte of one pixel
>> and the high byte of the _next_ pixel).
>>
> OK, interesting program. I'll try it tonight.
> 
> One more thing, what are you thinking about output image quality ? Is that
> normal with todays calibration or is it another problem ?

Well, i, for one, can see the impurities of the white inside of the
scanner lid. There are only very faint vertical lines, if at all.
Example attached.

> Regards
> Guillaume
> 
>>> Regards
>>> Guillaume
>> Regards,
>>   Pierre
>>
>>> Pierre Willenbrock a écrit :
>>>> Guillaume Gastebois schrieb:
>>>>> Hello,
>>>>>
>>>>> Yep, I write "for (j = 150; j...." instead of "for (i = 150; i....."
>>>>> Now second set seems good. Result is on :
>>>>> http://ggastebois.free.fr/lide90_snoop/20_test1.tar
>>>>>
>>>> Hi,
>>>>
>>>> i am sorry, i actually wanted 450, but didn't realize until just now. I
>>>> missed that the calibration dump images are really grayscale images,
>>>> although stored in color pnms. 1 pixel in image is 3 pixels for the
>>>> calibration...
>>>>
>>>> I hope this fixes that part of the calibration.
>>>>
>>>> Regards,
>>>>   Pierre
>>>>
>>>>> Regards
>>>>> Guillaume
>>>>>
>>
> 
> 
> 

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