[Digikam-users] Exposure correction shift(linear) strange behavior

Pedro Celestino reis at fc.ul.pt
Mon Nov 25 19:29:27 GMT 2013


Thank you very much for your prompt answer!

I can now provide some additional info. I was reading libraw manual and I 
found this entry:

*int exp_correc; float exp_shift,exp_preser;*
Exposure correction before demosaic. 

     *  exp_correc: positive value turns the feature on (default: off).
     *  exp_shift: exposure shift in linear scale. Usable range from 0.25 
(2-stop darken) to 8.0 (3-stop lighter). Default: 1.0 (no exposure shift).
     *  exp_preser: preserve highlights when lighten the image. Usable range 
from 0.0 (no preservation) to 1.0 (full preservation). 0.0 is the default 

I supose that it corresponds to the parameters in the Exposure Correction 
section of digikam "raw import tool configuration", as the image at 
http://userbase.kde.org/images.userbase/1/11/WhiteBalance.jpg suggests.

If I understood it correctly, it says that the neutral value (no exposure 
shift) should be 1.0, not something like -1.5 as it is being now. Moreover, 
it says that the values should allways be positive (min 0.25 and max 8.0)

I think that the behavior changed after upgrading libkdcraw22 from version 
4:4.10.5 to 4:4.11.3-1. May it be relevant, I can try to downgrade to 
confirm this.

Thank you for the great work


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