Mick I'm no expert on this, only dabbled a bit. Tone mapping is often associated with High Dynamic Range (HDR) photography where several images of different exposure are merged together and then tone mapping applied. The tone mapping seems to exaggerate contrast and colour saturation locally within the image and you can adjust the strength of the effect to suit your taste. But I'm sure there are many members of this forum who could explain it better than I.
In this case, I have used tone mapping on a single image using a plug-in for Photoshop from Media Chance called Redynamix. It is a plugin which includes some of the functionality of their stand-alone HDR software called Dynamic Photo HDR which can also be used for single images.
Cheers Dave
For me, that helps with the rather dull foreground but it is too much for the sky.
I think I would probably play around with a duplicate image layer and some masking to produce a more selective result.
Or a bit too blue. The overall contrast is better though.