You may have been told that a “good” histogram looks like this – all the way from black blacks (left) to white whites (right):
So this one is bad: no blacks, no whites:
As they say: it ain’t necessarily so. Not at all, in fact. The second histogram belongs to this foggy image:
While if we changed the histogram to what you thought was a “good” one, we get this:
Which is all very well if you intended that – and you might well, but it is not how that morning looked. It looked like the first image.
So here’s the skinny:
The histogram should go all the way to the left (pure black) if there are (or if you want there to be) blacks in the scene, and it should go all the way to the right (pure white) if there is (or if you want there to be) pure white in the scene.