- Create a new adjustment layer over the original image so your work is a flexible adjustment. Make sure to check the Layers panel to ensure you’re working on the correct new layer.
- Using the Lasso tool, make a selection that goes along the edges of the teeth. If you capture some of the lips or gums, that is OK.
- In the adjustments drop-down menu, select the Hue/Saturation adjustment layer. Photoshop will automatically convert your selection into a layer mask.
- In the Properties panel of your Hue/Saturation layer, click the options bar labeled Master and select Yellows, as that is all you’ll want to adjust to whiten teeth.
- Decrease the Yellows in your selection by moving the saturation slider to the left.
- If you notice a harsh edge to your selection, fix it in the Properties panel by selecting Masks. In the Masks panel, increase the feather slider to give your selection a soft edge.
