Three Ways to Use Select Subject and Select Background in Lightroom Classic

by Andrew S. Gibson
Three Ways to Use Select Subject and Select Background in Lightroom Classic


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Last month we looked at the Linear Gradient and Radial Gradient tools in Lightroom Classic’s Masks panel. Today I’m going to continue the theme and look at some of the ways you can use one of Lightroom’s newer AI masking tools, Select Subject and Select Background.

What is Select Subject?

Select Subject is an AI Masking tool in Lightroom Classic. When you use it, Lightroom uses AI to detect the subject of your photo and mask it. 


Note: In Lightroom Classic, a mask is another word for a selection. This is the opposite to Photoshop, where you make masks to cover the part of a photo that you don’t want to apply an effect to.


What is Select Background?

Select Background is another AI Masking tool in Lightroom Classic. When you use it, Lightroom uses AI to detect the subject of your photo and then inverts the selection to mask the background of the photo. 

In earlier versions of Lightroom Classic you had to make a Select Subject mask and invert it yourself to get the same result. Now Lightroom Classic can do it for you.

Why are Select Subject and Select Background so useful?

Select Subject and Select Background make it much easier to make selections in photos in Lightroom Classic. They let you to make local adjustments that were too complex and time-consuming to apply before they existed. 

How to use Select Subject and Select Background

Start by clicking on the Masking icon under the Histogram.

Masks panel Lightroom Classic

If the photo doesn’t have any masks, then you’ll see this display.

Masks panel Lightroom Classic

Click on Subject, Sky or Background to create an AI mask. In this case, I clicked Subject to make the AI mask you can see in the screenshot below, marked in red.

Select Subject Lightroom Classic

Lightroom automatically named the mask Mask 1. I recommend right-clicking the mask, selecting Rename from the menu and renaming it to something more helpful, like Subject.


Note: With portraits you’ll get a similar result using Select People, which I’ll cover in more depth in a future article.


Now click the Create New Mask button and then Select Background from the menu. Lightroom creates a new mask that’s the exact inverse of the Select Subject mask. Rename it to something like Background.

Select Background Lightroom Classic

Tip: Select Subject and Select Background work best when your photo has a clearly defined subject. 


Select Subject / Select Background example 1

Now let’s look at how you can use those masks we’ve just created. With this portrait I’d like to bring out the shadow detail in the model’s hair, increase the contrast and add texture. I’d also like to experiment with making the background lighter or darker. Here’s the photo before the adjustments.

Select Subject Lightroom Classic

First, I went to the Select Subject mask and moved the Texture, Clarity and Shadows sliders right.

Then I went to the Select Background mask and adjusted the Highlights, Shadows and Exposure sliders to make two versions of the portrait, one with a lighter background and one with a darker background. You can see both below.

Select Subject Lightroom Classic
Select Subject Lightroom Classic

Which approach you prefer is up to you, but it shows how you can use masks to apply different looks through a few simple adjustments. AI masking speeds up the process by making it quick and easy to make the masks. That lets you focus on experimenting with different effects.

Select Subject / Select Background example 2

Select Subject and Select Background come in useful in other photos as well. For example, in the photo below I’d like to apply Clarity to the building, but not the sky, to bring out the interesting textures. I’d also like to experiment with adjusting the color temperatures of both subject and background individually. 

Select Subject Lightroom Classic

I started by using Select Subject to mask the building.

Select Subject Lightroom Classic

Then I moved the Clarity slider right to add contrast and emphasize the texture of the stonework, and the Temp slider right to warm it up.

Select Subject Lightroom Classic

Next I used Select Background to select the sky. You could also use Select Sky with a photo like this, the result will be the same.

Select Background Lightroom Classic

I moved the Exposure slider left to make the sky darker, and the Temp slider left to cool the color temperature down, creating more color contrast with the warm stonework. This is the result.

Select Subject Lightroom Classic

Select Subject / Select Background example 3

Here’s another example of how Select Subject and Select Background work together. Here’s the photo I’m going to use.

Select Subject Lightroom Classic

I’d like to make the bottle stand out more by applying Clarity and making the background darker. To start, I created a Select Subject Mask.

Select Subject Lightroom Classic

I added Texture and Clarity to bring out detail. The bottle has some bright highlights, so I moved the Highlights slider left (-77) to make them darker, then Exposure right (0.29) to brighten the bottle back up again. This is the result so far.

Select Subject Lightroom Classic

Then I made a Select Background mask. 

Select Background Lightroom Classic

Then moved the Exposure slider left to make it darker, and the Saturation slider left to reduce the intensity of the colors. This is the end result.

Select Subject Lightroom Classic

More AI masking tips

These three examples show you how the Select Subject and Select Background AI masking tools work and give you some ideas for using them on your own photos. 

Remember you can modify both Select Subject and Select Background masks by adding or subtracting another mask, or by intersecting them with another mask. 

You can also use them in Develop Presets by checking the appropriate boxes in the Create New Develop Preset window.

When you apply a preset with a Select Subject and a Select Background mask Lightroom recalculates the masks every time you apply the preset to a new photo, and applies the settings in the preset accordingly. The same time saving idea also works when copying and pasting settings from one photo to another, or to a group of photos (batch processing).




Mastering Lightroom Classic: Book Two – The Develop Module

You can learn more about masking and the Masks panel in Lightroom Classic with my ebook Mastering Lightroom Classic: Book Two – The Develop Module




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2 comments

Frank A W Schweitzer March 22, 2023 - 9:54 am

great seeing the masking in the new L’oom advocated by Pros

Reply
Connie Petty March 25, 2023 - 1:24 am

Thank you for this post breaking down the different uses for background & subject. Very helpful.

Reply

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