PHOTOSHOP TIPS FOR AVIATION PHOTOGRAPHERS - ADJUSTING CONTRAST USING CURVES

Adjusting the contrast of an image will turn a flat looking picture into one with depth:

(1) Create a separate Curves adjustment layer.

(2) On the RGB channel select points near the top (highlights) and bottom (shadows) of the graph. By dragging the bottom point down and the top point up so that the graph becomes slightly "S" shaped you are increasing the tonal range (contrast) of the image.