[sane-devel] HP Scanjet 5590: Scanning in Grayscale - Mode

Stefan Kempf steke at gmx.net
Thu Apr 2 19:29:36 UTC 2009

Hi Ilia,

oh-ha, thanks for info.

" ... These calculations gave near the same tables as original Windows
drivers sent...."
if I look at the two histograms - I could mail them to you -
it looks like a 'not too small' difference.

"...That could be because the scanner receives two tables (maps), I've
called them calibration ones. And in the SANE backend I've used just a
simple calculations...."
 From what does the scanner (you mean the hardware?) receives the  
form the frontend?
or does the backend receives the calibration table form the scanner?

I believe, I haven't figured it out in detail. But if you do some
increments and decrements of
the grey- or color-values and the values are concentrated at one end  
of the
histogram, my desired ;-) details (of the image) could be lost.

"...Looks like the maps are for each color channel..."
The idea with the color channel could be right, because scanning my
drawings in color-mode gives the same result (not to much details on the

"...and depend on scanning parameters (brightness, thresholds etc)...."
within limits, yes. All possible paramters (in xsane) turned to many
values, the results are although poor. The strong lines getting more  
or less
intensive but weak details are totaly ignored whatever parameters are  

If those maps are the color-maps, is there an alternative, to get them
uncalculated? Or is this, what you meant with

"...Another way is to receive the maps directly from a frontend thus
offloading the calculations...."
As I've understood, the backend does the calculations, right? So, the
frontend must get the uncalculated data to give them further, right?
Then, should I have a switch for the backend to get the uncalculated  

And do I've a chance to get the uncalculated data?

Best Regards
Stefan Kempf

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