I'm sure that even the free version of PS will allow some levels adjustments so here we go.
Ok we will take a shot that has come straight from Raw file and saved as a jpg.
The levels adjustment when used manually allows you to have even more control over how things are adjusted. If we take the following image again straight from camera and load it into PS.
Whilst I have not made any massive changes as you can see the image is enhanced by some subtle changes to the sliders.