Hi Armand! Thanks for that file. So I loaded it up in the latest lightroom and had a go at the file. Here are the files, what I see, and then my explanation at the bottom.
File 1: As shot. This is what you provided. When looking at it objectively I see an image exposed purely for the sky brights. Moody and dark everywhere else.
https://www.dropbox.com/s/lyka2nxp6650c0o/Olympus_test1-as-shot.jpg?dl=0File 2: Exposure lifted +4. This is raising the exposure in lightroom 4 stops!
https://www.dropbox.com/s/47vgnwej5ot180l/Olympus_test1-exp-plus-4.jpg?dl=0File 3: Exposure pushed +5 stops, shadows pushed to 100% brighter, and darks pushed to 100% brighter. That's is just ripping the file to the extreme for demonstration of the "purple."
https://www.dropbox.com/s/9v6aqu0ybulgm14/Olympus_test1-max-exp-shad-dark.jpg?dl=0File 4: My own adjustments in lightroom to create what I feel is an optimal image based on the data that was recorded...assuming that you are trying to show the entire scene and not just the sky.
https://www.dropbox.com/s/48786t2tbz1ecep/Olympus_test1-optimal.jpg?dl=0All my adjustments were quick basic lightroom adjustments. My honest opinion is that few images would hold up to this kind of extreme adjustment. My medium format gear can handle a +4 boost just fine...as long as you dont touch the shadows additionally. The Olympus handled the exposure boosting 4 stops just fine too without going ugly purple. Honestly, if I have a file that I meant to capture the entire scene, and it was still that dark after 4 stops... I screwed up. Bottom line. No miracles to expect...I just needed more exposure to be recorded. I would have shot two images. Or three. This is also a perfect scene for a graduated neutral density filter. I understand this is an extreme example, but I also think as photographers in general we need to know what the cameras can and cant do. I dont think any camera out there is capable of pulling more than this cleanly. In fact, for a sensor as small as a m4/3 sensor, this is exceptionally good. In fact I know for a fact my Canon full frames would have fallen apart just as hard. I've done the tests myself.
This all comes down to what do we want. What are we after as photographers, and what are we doing when we hit the shutter? Was this file intentionally shot like this thinking "oh ill open it up later?" Or was it shot for the sky and "oh wouldnt it be great now if I could see more?"
I am certainly not directing this to you Armand. I am glad you posted an example. I think this is a good exercise for everyone to see. It comes down to what we want...and I feel the file I show as optimal in my opinion, based on my own adjustment preferences is more than acceptable based on what I started with. If I go to black and white, I have even more liberty to push it. I bet if you print this, it wouldn't even be that bad up to 14 inches. In fact all non-photographers wouldnt think twice.
Anyways, thanks again. Very cool. I'de love to hear opinions. Again, my processing is my own choice, I am sure others would have done this differently. Not here to knock any one.