In response to a few questions, here’s some more on the Dehaze thingy in Lightroom CC. For comparison, you can see an unedited version, one where the normal contrast slider has been used, and one with dehaze applied. You’ll see that dehaze has pulled in more detail in the castle, but an odd vignette has also appeared.
In practice, I’d use this as part of the process rather than just as a single adjustment, but this does give an idea of what it can do.
Anyway, here’s Harlech Castle again:
And here’s a version with lots of contrast added:
That didn’t really make a lot of difference. So how about extreme amounts of dehaze?
Well, i’d want to lose the darkening in the corners, and make some other adjustments, or indeed not bother with such an extremely misty image as this one, but I think this does have some use…