D&B Non-destructively
Dodging (lightening) and burning (darkening) selected area of your image, especially shadows, are a powerful way to add contrast and "depth" to your image.
The downside is these tools are destructive i.e. they phyisically alter your image and if you overcook it (apply the effect to hard) it is really hard to recover.
Fortunately you can dodge and burn non-destructively. This example uses PS but the process works for many editors.
Select your layer of interest then click the adjustment layer and select "curves". Do this again so you have two curve adjustments. Command-i (cntl-i for Windows) click the masks to invert them so they are black.
Double-click on the name of one and rename it Dodge. If you are learning you can call it Dodge (brighten). Now click on the histogram icon. Within the curves tool, click-hold the line towards the top and drag it up slightly. Do the same again about 1/3rd from the bottom. See the top image - less is more with this tool, you just want a gentle curve just above the line.
Double-click on the other curves adjustment layer name and rename it Burn. If you are learning you can call it Burn (darken). Now click on the histogran icon. Within the curves tool, click-hold the line towards the top and drag it down slightly. Do the same again about 1/3rd from the bottom. See the bottom image far right.
Option-click (Alt-click) on the line below one adjustment layer to link it to the image layer. Do the same for the other adjustment layer. You should see a downward arrow as in the central image. This means the adjustmens are for the layer below ONLY (a good thing usually).
Now select a soft brush (big feather) with white paint and a flow of 50% or less (I often use 10 or 20%) and paint in the MASK for the effect you want. Paint in the Burn mask to darken the image, in the Dodge mask to lighten it. The center image shows the stalk has been brightened and the edge of the Magnolia has been darkened. If you over do it simply swap your colour to black and paint out the mistake.
You can, of course, click the histogram icons again and re-adjust the curves to make the overall effect stronger or weaker dependant on what the image needs, and what your initial choices were. If you save as a PSD file all these options will be available when you return to the editor next time.
