GIMP Version: 2.8.4
Operating System: Windows
GIMP Experience: Beginner Level

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Ello all. Im back with an interesting question. Actully two of them. First, if i had a business question about photography where would i post?

Second. I want to create 2 photos from the original photo. One under exposed and one over exposed. How would i do that? Curves and levels tool? To my understanding, exposer is the amont of light. So under exposed is darker and over is brighter. So does that mean midtones on the curves is brighter and darker or the whole image is lighter? My goal is to take the 3 images and overlay them.

The Brightness control should do a good job at emulating slight over- and under-exposure (+/- 2EV).

But if you are trying to do some exposure blend, this won't really work. Exposure blend is done using 3 different pictures, to take advantage of the extra information in the light tones of the the under-exposed pic and the dark tones of the over-exposed one. So you actually add information in the picture. What you will do with your technique is ruin the color information in the under- and over-exposed versions(*) and add that to your original picture. So you will at best get what you would obtain by selecting part of your picture and adjusting brightness for it.

(*) In 8 bit processing, you have 256 levels per channel. All color operations map the 256 original levels to some other level. You have the additional constraint that the target levels are in the same order that their respective source levels (ie, the curve is always increasing). The end result is that you end up with less different levels than you started with.

Hmm interesting. I'm going to have to toy around because I'm trying to do hdr without using plugins