Whitening teeth is easy with these two tools
Probably the top three things a good retoucher needs to know is how to erase blemishes, remove red eye and whiten teeth. And while there is a Red Eye tool in Photoshop CS2 designed to erase red eye, there is no Teeth Whitener tool. But it’s actually not too difficult to do it with Photoshop’s current tool set, specifically two tools that have been around since the early days of Photoshop and even before then, back when retouching was done in the darkroom.
What makes whitening teeth so easy is that your end result isn’t going to have much color to deal with. If you remove red eye but make the eyes gray as a result, well, people will notice. Working with the teeth is a lot more forgiving. Sure, you may be working with a photo of an old man with teeth as yellow as a Post-It note, but when people think of teeth they think of the color white, so as long as you get those chompers white or gray, or whatever shade makes sense for that particular image and light, then you will have a respectable image.
Use the Sponge tool
This is my favorite tool to whiten teeth, and it works best when the teeth you’re whitening are fairly bright but just have a yellow cast to them. The Sponge tool is basically a tool for spot-reducing or spot-increasing the saturation of a part of an image. If you open the Hue/Saturation dialog box (Image -> Adjustments -> Hue/Saturation…) and fiddle with the Saturation slider you will see what the Sponge tool does but on a global scale. Positive values increase color saturation to the point of fluorescence, while negative values decrease color saturation to the point of grays, or absence of color.
The Sponge tool does not deal with positive or negative values like the Hue/Saturation dialog box; its interface is more like a brush’s, with a flow rate and brush tip options. The key to using the Sponge to whiten teeth is to use the Desaturation option in the Mode drop-down menu. With this selected you’ll be removing the yellow color in the teeth and leaving its natural white value, whether white or off-white.
Figure 1 is an example of teeth with good bright values but with an undesirable yellowish cast. I set my Sponge tool for Desaturate and set the flow rate to 50%. You can set it to 100% or whatever works best for you, but I like to use a lower flow rate and go over an area a few times to gradually make the change. That way I don’t go from “too yellow” to “too gray” in one stroke. And this tip doesn’t apply to just the Sponge tool, either: using lower opacity and flow percentages when using any of Photoshop’s brush or spot-retouching tools will help you gain control over you retouching.
Tip: Use lower flow or opacity percentages and gradually brush an area for better control when you are retouching.
I use a soft-edged brush tip so there are no sharp differences between the retouched and untouched areas. After three or four passes across the teeth with my Sponge tool I have Figure 2 below, with teeth that are nice and neutral and have little noticeable color. And as I mentioned earlier, though the teeth are not pure white they are natural white, and will look great to the average person.
For deep cleaning, use the Dodge tool
Sometimes you want more than naturally white teeth: you want really white teeth, or even glow-in-the-dark teeth. With Halloween coming up, this would be a very timely technique! The best tool to do this is the Dodge tool, which looks like a black lollipop in the Toolbox and complements the Burn and Sponge tools. All these tools originated in the darkroom, and professional darkroom photographers still use these tools today. Photoshop, back when it was an extension of the darkroom, carried many of these same photographer’s tools and are still a part of the Photoshop tools, even in this era of Camera RAW and DNG.
Using the Dodge tool is very similar to using the Sponge tool. The main difference is that the Mode drop-down menu in the Sponge tool’s options is now the Range drop-down menu for the Dodge tool’s options. The Dodge tool works with a specific range of values at any given time, and it is in the Range menu that you will specify what that range is. Unfortunately there are only three options: Highlights, Midtones and Shadows. You have very little control over what you can edit with the Dodge tool, unlike the Hue/Saturation dialog box in which you can control the range a great deal.
For this technique, we are editing the light pixels of the teeth so choosing the Highlights range works very well. As with the Sponge tool, select a soft-edged brush and set exposure (which is the same as the Sponge tool’s flow rate) to 20%. I find the Dodge tool goes a long way, and you will often work with exposure with 20% or even less. We’ll use the Dodge tool on Figure 2, which has already been treated with the Sponge tool. Brush over the teeth and they will brighten. Figure 3 is the final image, with bright white teeth. It only took a single pass with 20% exposure to achieve this brightness.
The Dodge tool can brighten your teeth to the point of being pure white (see Figure 4), so use this tool with care.
The Sponge and Dodge tools are two of your best friends for whitening teeth. Rather than introducing white pixels to your image, these tools work with the pixels that are already there and thus ensuring that your retouching won’t seem fake.
In a future article I will discuss the Burn tool, the third tool bundled with the Sponge and Dodge tools in the Toolbox. Together these three tools are an important addition to your retouching arsenal.