How to programatically adjust exposure based on image metadata?

by Alexander Shenkin   Last Updated August 10, 2018 10:18 AM

As part of a photogrammetry project, I took a number of photos (in NEF RAW format) of an object using manual settings on a D800. However, I forgot to turn off auto-iso (argh!). So, all my photos have the same aperture and shutter speed, but they differ in their ISO. Is there some way I can adjust the exposure in each photo to remove the effect of the changes in ISO between photos, such that they will have the same exposures across photos as I originally intended?

I think the adjustment in EV units would go something like this: exposure_adjustment = -log2(ISO/baseISO). Any thoughts about how to carry that out? Would using ImageMagick or some other tool be appropriate?

Thanks, Allie

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