How To Use AutoMask In Lightroom


Masking: Lightroom’s Little Secret.

Masking has often been seen as a preserve of Lightroom’s older sibling, Photoshop. Often used in combination with layers, it is used to mask out parts of an image in order to manipulate specific areas or to create composites.

However, Lightroom also has a very powerful masking feature that also has an AutoMask capability. However, without layers, why would we need masking in Lightroom?

Editing The Details

Lightroom has three powerful tools for adjusting areas of a photograph. They are Graduated Filter, Radial Filter, and Adjustment Brush. Each of these tools can target a specific area of a photograph and allow us to make specific adjustments only to that area. 

The Graduated Filter and Radial Filter are relatively blunt tools when it comes to defining an area to edit. The Graduated Filter defines an area by straight lines and feathering, while the Radial Filter does similar using ellipses. What happens when we need to redefine an area within the selection?

Fortunately, Lightroom now allows users to “brush” back an edit using a masking brush. More importantly, we can use AutoMasking to speed up that procedure. Here’s how we do it. 

Our original image

Auto-Masking With The Graduated Filter.

We are going to demonstrate the power of masking using this drone image of St Michael’s Mount in Cornwall, England. Its a nice looking shot but the sky is a bit light and bland looking.

By applying a Graduated Filter we can pull back the sky but the obvious problem is the upper section of the island will also be affected. Let’s apply the Graduated Filter and see what happens.

The Graduated Filter is found third from the right on the brush tools. To apply it, in this case, we drag the mouse down from the top of the picture to just below the horizon level.

To give the sky a little more punch, I have reduced exposure, added some clarity and dehaze and increased the magenta tint.

The problem is that the upper half of the island has also been affected. We can see this when we click on Show Selected Mask Overlay at the bottom of the image. The edit goes right through the island.

Select the Graduated Filter


Graduated Filter Applied with Mask Overlay. You can see the filter bisects the island.


Adjustments made to the Graduated Filter

Editing The Filter Mask

To eliminate this problem, while in the Graduated Filter tools, we click on Brush at the upper right of the panel. At the bottom of the panel, we click on AutoMask. Because we wish to erase the adjustments in this part of the selection, we need to select Erase in the Brush options.  

We now set out brush size to something suitable, this can be done using the mouse scroll wheel, and start to carefully paint over the areas of the mask that we wish to return to normal. In this case the island and castle. 

Select the Brush, Erase and AutoMask

As we paint, the AutoMask will workout the contrast between areas that we wish to erase and the areas we wish to keep. As it erases the mask, we will see the original natural colour begin to appear.

In this image, I will paint out, or erase all the red masking on the island area leaving just the sky affected by the Graduated Filter. To get into the detailed areas we can zoom into the image using CMD= (Mac) or CTRL= (Windows).

We can then reduce the brush size to paint out some of the intricate areas, in this case, the tree-line. To move around in the zoomed view, press the spacebar and drag on the image. 

Paint out the areas we wish to restore, zooming as required.

Once you have completed the edit, you can zoom back out using CMD/CTRL-. Click on the Show Selected Mask Overlay box to remove the red mask and reveal the fully edited image. As you can see, we have restored the island and castle to their natural dawn beauty while adding much more punch to the sky.

To summarise the procedure:

  • Add a Graduated or Radial Filter
  • Make initial adjustments
  • Select Brush, Erase and AutoMask
  • Brush out the areas you wish to restore.
The end result

AutoMask is an extremely useful and often under-used part of the Lightroom toolkit. While many of us might use the Graduated and Radial filters often, we sometimes forget we can make detailed adjustments to our selections.

Next time you use either of these tools, look more deeply at the image and see if there are some areas that might benefit from some more detailed editing using the Masking Brush and Auto Mask 

About Author

Jason has more than 35 years of experience as a professional photographer, videographer and stock shooter. You can get to know him better here.

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