I would use the app to take pictures with each color effect applied, and without (I think you can save both).
Then bring them into GIMP, and use something like elsamukos awesome "Get RGB Curves" plugin to extract the color curve changes to produce the effect.
You'll need to account for the vignette that is applied, but the curves should get you pretty close to what you want right off the bat. I might fiddle with the curves to smooth them out, though (set the curve type to "smooth" for each channel).
I'll write up a tutorial and package up all of the effects that are applied shortly (busy at work this week).
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