Updated: Aug 8
There are many times when you want to adjust only a portion of a photo. In Lightroom, you can accomplish this using what Adobe calls an “Adjustment Brush”. Most people refer to this operation as “masking”. This discussion uses Lightroom 6.14.
Mask overlay shown in red
To show the mask (adjustment brush) option, select the Tools | Adjustment Brush or else just press the “K” key.
When using the mask, the mask brush will look like two concentric circles. The inner circle is solid, showing how far the full masking effect extends. The outer circle is dashed, and shows the extent of the mask edge feathering. The start of the mask (the ‘pin’) is a little white circle with a black center. There are two more sliders for masking control called “Density” (mask opacity) and “Flow”, which is the percent opacity per overlapping brush stroke.
Change the diameter of the masking brush by using the mouse scroll wheel. Change the diameter of the feathering effect by using Shift+Scroll wheel.
View the mask as you draw it by selecting the Tools | Adjustment Mask Overlay | Show Overlay. While you’re drawing the mask, the middle of the brush mask will have a “+” to show you’re adding to the mask. You can also click the “O” letter to toggle viewing/hiding the (red) mask.
To fix masking mistakes, click the “Erase” button (shown above). The middle of the brush mask will have a “-“ to show you’re subtracting from the mask. If you decide to get rid of a mask, click on its ‘pin’ marker and press the Delete key. You may have to scroll down to see the “Erase” button.
There’s an option to change the color of the mask overlay, in case you’re masking something that’s already a shade of red, for instance.
Mask “Effect” menu
To choose an effect with predefined settings, you can select from the Effect menu. The “Exposure” setting is shown above. After you select an effect type, you’re free to adjust the sliders to customize the effect to your own taste. In the example above, the goal is to select just the sky. Note above how difficult it is to try selecting only the sky by just brushing. There is a solution to this problem, and it’s called “Auto Mask”.
Mask just the sky with “Auto Mask” to select a color
If you’re trying to mask an area that has a particular color, then “Auto Mask” is for you. As shown above, I was able to paint the mask onto the blue sky, and it left the white sails alone. In this example, I decided to selectively adjust the saturation. I clicked the “O” key to see the saturation effect, instead of showing the red mask.
Adjust the sky saturation
After the mask drawing is finished, remember to click “Done” to complete the mask operation.
“Soften Skin” effect
Use Keys to Control Masks in a Hurry
For a common task such as skin smoothing, invoke a mask by pressing the K key. Next, you can select “Soften Skin” from the “Effect” drop-down menu and immediately start drawing with the mask. Use the mouse scroll wheel to adjust the brush diameter and use Shift-scroll for the feathering. To see the overall mask, press the O key to see the (red) mask, and you can toggle it off by pressing O again.
If you make a mistake and draw the mask somewhere you don’t want it, then click on the “Erase” button to fix the mistake. Click the “A” brush (next to the Erase button) to go back to adding to the mask where you want it. The “Auto Mask” option might help minimize drawing mistakes, depending upon the color contrast between the skin color and the hair/background color.
When you’re happy with the mask effect, click the “Done” button at the bottom of the mask dialog.
Enhance an eye iris with a mask
To make eyes sharper and more saturated, you can select the mask effect called “Iris Enhance”. Zoom in (Ctrl +) and use the mouse scroll wheel to get the mask to just cover the iris. The left-hand side of the ‘Develop’ window has a little white triangle that you can click and open up a thumbnail view of your photo. Mouse-drag the little white rectangle in the thumbnail view to navigate around the zoomed view and center the eye being worked on.
You will need a separate mask for the other eye. Again, remember to click the “Done” button to complete any individual mask.
Navigate around the zoomed picture via the thumbnail
The shot above shows the thumbnail navigation window, with a white rectangle representing the zoomed view. Drag the white rectangle to see that part of the zoomed picture. Remember that you can use “Ctrl +” to zoom in and “Ctrl –” to zoom out.
Masking in Lightroom involves memorizing a few keyboard key shortcuts and use of the mouse scroll wheel. I hope this little guide will make it a bit easier to effectively use the adjustment brush.