primax: Thread: D600 Calibration Problem?

I have had some success with my D600 (I am guessing its a 30 bit) with both
primax_scan and primaxd except for the following:

primax_scan:
==========
Without the -o the scan head moves forward an inch from its current position
and then sits there. I have traced the code and the problem is in
read_calibration_data - the while condition is never met.

If I specify the -o switch the scan works fine (but is a little dark).

primaxd:
=======

If I change RESOLUTION to 600 and start a preview scan in SANE, the scanner
moves about an inch and then SANE locks up. I haven't traced this through,
but suspect the problem is similar, the code layout has changed slightly,
but the functionality is the same.

Leaving the RESOLUTION at 300 causes only a 1/4 of the page to be scanned
(not surprisingly) and the whole scan has a yellow tint.

All help is greatly appreciated,

Kind regards,

Mike.

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Am Montag, 4. Februar 2002 15:02 schrieben Sie:
> I have had some success with my D600 (I am guessing its a 30 bit) with both
> primax_scan and primaxd except for the following:
>
> primax_scan:
> ==========
> Without the -o the scan head moves forward an inch from its current
> position and then sits there. I have traced the code and the problem is in
> read_calibration_data - the while condition is never met.
>
> If I specify the -o switch the scan works fine (but is a little dark).
>
> primaxd:
> =======
>
> If I change RESOLUTION to 600 and start a preview scan in SANE, the scanner
> moves about an inch and then SANE locks up. I haven't traced this through,
> but suspect the problem is similar, the code layout has changed slightly,
> but the functionality is the same.
>
> Leaving the RESOLUTION at 300 causes only a 1/4 of the page to be scanned
> (not surprisingly) and the whole scan has a yellow tint.
>
> All help is greatly appreciated,
>
> Kind regards,
>
> Mike.

Cool, finally someone with a D600 using primaxd. I really want to make it 
work. The problem was only, that I don't have a D600. 
So - let's do it.

(1) We could disable the calibration process in primaxd and it could work. 

(2) We could fix the calibration process for the D600. This is the only good 
way. My problem is that I don't understand the calibration code. I took it 
from primax_scan and it worked. But I have no idea of what it is doing. I 
also don't know the author and if he is still alive. 

We could try to figure out how it works. The problem seems that there a 2 
times of the lines scanned, that are scanned with 300 dpi. The calibration 
scans some area where a white and a black area is. The algorithm seems to 
look for the border. With only half of the area, it cannot find it and hangs. 

Does anyone has an idea how to fix this?

Andre

- -- 
Andre Herms                   ####@####.####
                              http://www.cs.uni-magdeburg.de/~aherms
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> Cool, finally someone with a D600 using primaxd. I really want to make it
> work. The problem was only, that I don't have a D600.
> So - let's do it.

Yes, I agree!

> (2) We could fix the calibration process for the D600. This is the only
good
> way. My problem is that I don't understand the calibration code. I took it
> from primax_scan and it worked. But I have no idea of what it is doing. I
> also don't know the author and if he is still alive.

Maybe Christian or Marco could help here?

> We could try to figure out how it works. The problem seems that there a 2
> times of the lines scanned, that are scanned with 300 dpi. The calibration
> scans some area where a white and a black area is. The algorithm seems to
> look for the border. With only half of the area, it cannot find it and
hangs.

I will try to capture the values that are returned both with the 300 dpi and
600 dpi setting.

Is this mailing-list the right place to discuss this??

Thanks,

Mike.

On Mon, Feb 04, 2002 at 04:36:28PM -0000, Mike Rothon wrote:
> > (2) We could fix the calibration process for the D600. This is the only
> good
> > way. My problem is that I don't understand the calibration code. I took it
> > from primax_scan and it worked. But I have no idea of what it is doing. I
> > also don't know the author and if he is still alive.
> 
> Maybe Christian or Marco could help here?
Marco, who did most of the reverse engeneering stuff seems to have vanished
from earth's surface ;-(

Thomas Schano has contributed the needed changes for the D600 to the
primax_scan CVS (I'm not sure but they should already be in the
latest Beta...), but since I also don't have a D600 I couldn't verify
this for myself.
 
> Is this mailing-list the right place to discuss this??
sure! which place could be mor correct than the project's mailing list.
(And yes, I have to admit questions to my private address and to the
project's "support" address come either very late or even seem to
take forever, because I am very busy with my studies these days.
_sorry_ to all the guys who are still waiting for an answer. Furthermore
it seems that I am the only one of the project's founders who is still
alive. :-( )


-- 
Christian Ordig
Germany  

Is there a description anywhere of what the scanner is trying to do during
calibration? I read in earlier posts that Primax released some
documentation, is this still available?

My assumptions are:

1. There are three passes of the calibration area during this process, one
each for Cyan, Magenta and Yellow. If I remove the calibration code then the
scan works, but the colour registration is poor.

2. A value for white and black is generated for each pixel(?) of the CCD and
these are put in a table. These are factored into the scanned values to give
a common brilliance level across the page.

If anyone can shed some more light on this area, it will be gratefully
received.

Many thanks,

Mike.

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Hi, 

> Is there a description anywhere of what the scanner is trying to do during
> calibration? I read in earlier posts that Primax released some
> documentation, is this still available?
>
> My assumptions are:
>
> 1. There are three passes of the calibration area during this process, one
> each for Cyan, Magenta and Yellow. 
I think, it's Red, Green and Blue.

> If I remove the calibration code then
> the scan works, but the colour registration is poor.

Does it really work with the D600 and the whole scan area. Did you try this 
with primaxd?

> 2. A value for white and black is generated for each pixel(?) of the CCD
> and these are put in a table. These are factored into the scanned values to
> give a common brilliance level across the page.
>
> If anyone can shed some more light on this area, it will be gratefully
> received.

Hmm - I read a little bit in the sane newsgroup. There are other scanners 
that work simmilar. The CCD contains many sensors, that don't give the same 
output for the same scanned color. So a correction value for every sensor is 
calculated and put into the registers. At the front of the scanner should be 
a black and white stripe (I hope so as I cannot see there). This area is 
scanned and used for the value correction. 

So far what I know.

Andre

- -- 
Andre Herms                   ####@####.####
                              http://www.cs.uni-magdeburg.de/~aherms
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