Nobody likes the dentist, and nobody likes to look bad in a portrait. Whether the cause is poor dental hygiene or just bad luck, you can now give your portrait subjects a better smile in just two easy steps. Best of all, they never have to know how you helped their smile.
There are lots of effective digital tooth-whitening approaches, but my own favorite is effective, quick and easy. I use Photoshop's desaturation sponge and the dodging tool to whiten dingy smiles with just a few clicks.The first step is to choose the sponge in the tools palette and set it to "desaturate." Scale the brush to fit easily within the teeth without overlapping onto the lips and gums, but keep it large enough to provide even coverage. Reduce the flow to 25 or 35 percent and begin the desaturation process with large even strokes. After desaturation, the smile isn't yet white, but at least it isn't an awful shade of green.
Gray teeth don't look much better than green ones, so we need to make them white. Choose the dodging tool and set its exposure to 10 or 15 percent and the range to "midtones." Slowly whiten the teeth without creating bright spots by setting the range for midtones; this will generally leave the shadows and already-bright-white areas untouched. It's important to avoid whitening the lips and gums, but with a soft brush the separation is pretty easy.
The most important part of any tooth whitening approach is to keep it realistic. Bright white smiles may sound attractive in theory, but a too-white grin actually looks unrealistic and odd. The subtle removal of stains and discoloration along with minimal brightening makes subjects look their best, which also makes them happy and makes you look like an even better photographer.