GIMP 2.10.38.
Out of curiosity I tried a couple of my plug-ins on this image.
The first was done with the Enhance Shadows plug-in, the second with my Luminosity Mask plug-in.
Played around with the tone equaliser mask for this, I hope it’s better than default. Didn’t feel the need for a tonemapper at the end, most of it was already in display bounds.
Light and shadows are making a picture lively and interesting. Instead of equalize them, I’m always happy when I have the possibility to emphasize them. So not necessarily what you asked for:
I just used a local gradient mask to brighten up overall exposure, plus a little extra boost to shadows and midtones. That seemed to help a lot with contrast in the bottom half of the image. I also applied a warm tint on top of the main color grade to give a stronger yellow/blue complementary treatment. A very beautiful spot and nice composition. Cheers!
Edited entirely with HDR Finisher. Project file zipped and attached below for your reference.
Here is my proposal, featuring my experimental branch "Libre DT-Lab with a fairly simple processing workflow. I used three modules: 3DCF, Contrast & Texture and Color Harmonize.
I’m not at all sure about this, but I tried to stick to the brief Using matched gradient masks to soften the background and lift the foreground without overcooking it. A difficult balance to strike. I used Color LUT to bring back some contrast in the clouds.
The more I look at other peoples’ edits, the more I think I must have missed the point of the assignment. Most of you seem to be going for a levelized exposure across the image. I tried to show that the background was in bright sun while the lead boats were shadowed by clouds.