Exposure Compensation

[SuperRoboWizard]

Based on some simple tests with a couple pictures, it would seem (at least on my device) that, after processing, the image is between about .5 and .75 EVs darker than before processing.
I'm not sure if this is something that could easily be fixed by changing how the gain map is applied internally, but in any case, I think an automatic exposure compensation pass would be a nice option to have.

Perhaps a simple algorithm could be to average the brightness values for all the pixels, then, if it's within a certain range of 50% brightness, adjust the exposure (or maybe gamma to preserve the endpoints? Not sure how that would look, and probably more complicated to do) to make the average match the midpoint.

For now, a suitable solution is to offset the exposure when capturing the image, but that makes it harder to determine what the final image would look like when setting up the shot.