You may already be familiar with Lightroom's masking features for those times you need to make selective edits to your photos, but did you know that there are also tools that let you easily refine the masks you create? Whether you made your mask using a brush, gradient, or radial filter, you can alter the mask using either color or luminance ranges.
How To Make A Luminance Range Mask
Luminance range masks allow you to refine your mask based on luminosity value. A typical example of how this comes in handy is when you want to use a gradient mask to reduce the exposure of the sky, but there are trees or people protruding over the horizon that you want to mask out. Without the ability to mask by luminance range, you'd have to brush the intrusion out manually, and doing that well in Lightroom would be very tedious.
With luminance range masking, you can make your gradient mask as usual and use a luminance range mask to select the luminance of the sky, and Lightroom will adjust the mask for you, easy peasy. Here's how to use luminance range masking:
First, make any type of mask - brush, radial, or gradient. Then, scroll to the bottom of the selective adjustment section where it says "Range Mask." By default, it is set to "off," but if you click the word "off" it opens a dropdown menu where you can choose which type of range mask to apply. Choose "Luminance."
After you select the range mask type, some new settings will pop up. There's an eyedropper you can use to choose the luminance range you want to mask directly from the image, and two sliders to adjust range and smoothness.
You can use the eyedropper to make a point selection by clicking anywhere on your photo, or you can click and drag to create a box that provides Lightroom a more extensive sampling of pixels. Once you've made a selection with the eyedropper, the slider handles on the range slider will move to correspond with the selection.
The range slider represents the luminosity values in the image from dark, on the left, to light, on the right. It has two handles, and before you use the eyedropper or make any adjustments, they are set by default to cover the entire range - one is pushed to the far left and the other to the far right. The area between the slider handles represents the luminance range that will get masked. When you use the eyedropper, the handles will snap to the range selected. You can move them to expand or contract the selection.
The smoothness slider adjusts how smooth or abrupt the transition from the masked area to the unmasked area is. A higher smoothness setting feathers the edge of the mask, and a lower one has sharper edges.
You can see the luminance mask you've created in two ways. There is a checkbox above the sliders labeled "Show Luminance Mask" that you can click to toggle in and out of a grayscale view mode, or you can use the "O" keyboard shortcut to toggle a red mask overlay.
How To Make A Color Range Mask
To make a color range mask, begin the same way as the luminosity range mask: make any kind of selective adjustment mask and scroll to the dropdown menu at the bottom of the tool panel. Then, from the dropdown, choose "Color." Selecting "color" will change the panel again - this time, there will be an eyedropper tool and an "Amount" slider that you use to expand or contract the mask.
Just like with the luminance mask, the eyedropper can make a point selection, or you can click and drag to create a more comprehensive sample. To see your color mask, use the "O" keyboard shortcut for the red overlay.
Color range masks work best on colors that are distinct in the image. If there are many similar colors in your photo, Lightroom will apply the color range mask to everything within the initial mask that is close to the tone you selected. If your subject is wearing a bright red shirt, it's easy to mask only the shirt, but if they're wearing a top that's close to their skin tone in color, you'd have to do more manual masking with a brush if you only wanted to mask the top.
In the example photo, a broad brush stroke was used to make a rough mask across the model's mouth, and then the eyedropper was used to quickly and easily make a perfect mask of just her lips. From there, you can use the sliders in the selective adjustment tool to change her lipstick color, no Photoshop required.