As part of my series of basic portrait retouching techniques, I want to give you some options on whitening teeth—Photoshop options, that is. I'm not here to sell you white strips or bleaching trays. In fact, I don't want photos that end up with fluorescent blue/white Regis Philbin teeth, just something realistic and a little less yellow. Here is the "before" picture:

The subtext of this tutorial is that the more you experiment with Photoshop, the more you will find alternative approaches to any given problem. Below are four possibilities. Choose one that works for you, or use them as inspiration for other methods.
The Adjuster
Method: hue-saturation adjustment
1. Duplicate your background layer (Mac: Command–J; PC: Ctrl–J)
2. From the top menu bar, choose Image-->Adjustments-->Hue/Saturation



4. Next, you are going to add a black mask over the layer you just adjusted and then paint the teeth back in so that the effect applies only to the teeth.
NOTE: Some people would tell you to select the teeth first and save yourself the step of painting later. Personally, I prefer painting, but this is just one example of how many variations there can be in method.
To create the black mask, hold down the option/alt key while clicking on the mask icon at the bottom of the layers palette.
5. Select the brush tool (b). With a medium-hard brush, and with white as your foreground color, paint over the teeth (but not the gums) to reveal the hue/saturation changes you just made.
(insert brush teeth image)
NOTE: If you want help seeing where you are brushing, you can turn on a red overlay by hitting the backslash (\) key:

6. Once you have painted the teeth, you can play with the opacity of that layer to tone down the effect as needed:

Once again, here is the before:


The Hygenist
Method: Dodging
1. Duplicate your background layer (Mac: Command–J; PC: Ctrl–J)
2. In the layers palette, change the view to Channels and click on the Blue channel:


3. Select the dodge tool and set it to a low exposure (7-10%)


Here is the before:


Conclusion for The Hygenist: I call this technique "The Hygenist" because it really starts to feel like you are cleaning the person's teeth. Pro retouchers swear by (and at) dodge and burn. They can use it in amazing and diverse ways, but they also talk about doing it until their eyes bleed (not unlike that lame character on Heroes). You have the potential for the best results (and don't judge that solely by the above image, because as I have stated, I use "The Adjuster."), but the learning curve is relatively high.
The Fluorescent Fix or The Tamed Regis
Method: Channel Mixer
1. Duplicate your background layer (Mac: Command–J; PC: Ctrl–J)
2. From the top menu select Image-->Adjustments-->Channel Mixer
and in the dialog box, select Blue as your Output Channel:

4. Mask out the effect and then paint in the teeth as in steps 4 and 5 of "The Adjuster." Here is the frightening smile midway through:

Here is the before:


Not bad for something I made up this morning. With more fine-tuned adjustments this could be a reasonable and quick fix. The one problem: it seems easier to over-correct on this one.
The Painter
Method: Painting
1. Duplicate your background layer (Mac: Command–J; PC: Ctrl–J), but set your blend mode to "lighten."
2. Use the paint brush (b) on your duplicate layer to paint over the teeth. You will need to double click in the foreground color box and select a good tooth color. You may even want to change and use more than one color. I used some colors from a "long in the tooth" palette on Colourlovers. My choices yielded pretty extreme results. You can even tell from the tiny thumbnail in the layers palette:

Here is before:


Overall, the painting brought memories of the tacky "photo" plate of my older sister that some creepy guy stationed in Korea once sent to woo her (What is that even trying to say? I hope that each time you look at this photo of yourself on a plate, you will think of me?). Her eyes had changed from blue to brown; her bottom lip had been moved to create what someone must have imagined to be a more demure smile, and her teeth were cartoon-white. Like I said, I am sure that someone with more skill in painting could achieve better results, but I couldn't get the teeth as white as I wanted to without having the image of the Korean photo plate pop into my mind.