Using Curves to Dodge & Burn
Although the Curves Adjustment Layer is a good way to make an overall tweak to the look of an image, I bet you never thought of using it for easy Dodge & Burn without shifting or dulling the color like the Dodge/Burn tools in CS3 and earlier will do. Although Adobe has “fixed” the Dodge & Burn tool in CS4 so they function much like the trick below, you can still use this trick for non-destructive dodge & burn in CS4 if you like.
First off, create a Curves adjustment layer at the top of the layer stack.
To Dodge, you will want to drag a point from the middle up some creating a bend in the curve as shown. Because you are working with an Adjustment Layer, you can always edit the curve again later. Don’t drag it too far, just enough to bring the places you want to dodge to about the maximum level you would want them. Again, you can always change the curve later or add points to make it add contrast as well using an S curve shape. Now here is the trick to make this really work well… Change the layer blending to Luminosity.
Next, with the layer mask for the new Curves layer selected, fill it with black to hide everything. (Shortcut: Command+Delete on Mac fills using the background color, Option+Delete fills using foreground color.) This is where you will do your dodge “painting” using the white paintbrush. Since you are working with a layer mask, you can get a little sloppy and clean it up later where as working with the Dodge & Burn tools you don’t have that luxury. Plus you can re-edit anything as you see fit later because the layer is completely non-destructive. I suggest using a large paintbrush with 100% feathering and at a low opacity to start with. You can always make multiple strokes to get it just right. (Here is where a tablet really comes in handy.)
To Burn, simply do the same thing as above for Dodge except drag the curve down to make the image slightly darker. Again, as above change the layer blending to Luminosity, fill the layer mask and paint with white over the mask to slowly burn in the areas you want. I find it helps to rename the layers to Dodge or Burn so I know which is which when I go to make a change later. (Notice I forgot to do that for this example.)
Of course if the effect is too strong, you can always tone it down a bit using the Layer Opacity. Just slide that down until you are satisfied. I also find it easier to make multiple adjustment layers to dodge and burn different areas so I can adjust them independently. Here is a fun one, try this using other types of Adjustment Layers and Blending Modes.
Edit: Due to some discussion regarding the Dodge & Burn tools and the popular “Soft Light” method, here is a tutorial on how to use that method. Soft Light Dodge & Burn