Oliver Rauch, Mittwoch, 24. Juli 2002 22:07: > You will not be able to save the data to a system directory > because all users need write access to the file. > Be carefull with security with such files!
I was thinking about saving the values on a per-user basis, not some sort of global config file. As long as the user isn't scanning over a network (saned/net), is there a problem with using the users $HOME/.sane directory for saving? > I suggest not to save any calibration data to a file. > The calibration data does not keep valid for a long time > because the illumination of the lamp does change, especally > for several minutes after the scanner lamp has turned on. I should mention, that this is a CIS device, I can't see any difference in the calibration values between scans(maybe over a long term of usage due to aging of the sensor/LED rows?). The windoze driver saves all the values to disk and avoids repeating the calibration sequence, which takes about 20 seconds (or more). > I suggest to keep the calibration data in the memory or > save it to a temporary file that is erased when sane_close > is called. That's what I do at the moment. Another approach was to use default offset/gain/exposure values in the .conf file (optional) and only do shading correction after sane_start is called the first time. The scanner will still work without those values and there's also a "Calibrate before next scan" - option to enforce calibration. The problem is, that this is a global setting which affects all users. > > small problem: > > Is there a well-known location, where a backend should/could save some > > data? I'd like to save some calibration data (shading,exposure ...), but > > I'm not sure how to do this. > > Should this go to $HOME/.sane ? Does this work with saned? bb Michael
