STEP 2: Use Layer Mask to Isolate the Teeth
Our step 1 changed the color of our whole image and we only want to desaturate the teeth. I am going to use Layer Mask to hide everything except teeth. Click on the white rectangular box next to the Hue/Saturation Layer.
Make black as your foreground (press D) color and then press Alt+Backspace/Opt+Delete to fill it with black color.
