[Digikam-users] Uniformizing histograms of a set of pictures

[Alexandre Courbot]

Hello everyone,

I'm a really happy Digikam user for a couple of years now, and it did
all I needed so far. Today I need to do something that may require
your advices.

Basically, I took a series of very similar pictures, under the same
conditions (place, actors, ...) with only a few details changing. My
problem is that the colors are not rendered exactly the same, as if
the exposure settings were changed (I suspect the neon light is to
blame here). The resulting pictures therefore have about the same
histogram pattern, but shifted left or right with respect to the
reference one. As I would like to display these pictures side-by-side,
I need to adjust the color levels such as the exposure is uniform
across all pictures. That is, shift the histograms of all pictures to
obtain the same pattern.

So what I would need is either a tool that could do that automatically
or at least, a tool that let me adjust the histogram manually (like
the adjust levels tool), but with a view of the histogram of the
reference picture. Is it possible to do one or the other with Digikam,
or any other tool available on Linux?

I am just a digital photography hobbyist, and know very little about
the matter - sorry if the answer to this question is obvious, but
after lot of research I haven't been able to find a single clue.

Thanks for your time,
Alex.