The latest versions of Lightroom and Lightroom Classic introduced a new masking feature that has created quite a bit of talk and excitement. I wrote an article about how the Select Sky and Select Subject feature work in low light.

This time, I thought I would challenge it further by testing how Select Sky interprets a a night photo with a dark, almost silhouetted Joshua Tree. With its spiky arms, shaggy leaves and long slender spines, the plant provides a challenge for any program that utilizes masking. 

A more challenging Lightroom masking test

To make it even more challenging, I selected a photo in which a Joshua Tree was mostly in shadow, backlit by only the moon and my light painting. The dark scene could potentially pose more issues with masking overall. 

For the many screenshots I am going to share with you, I’ve also zoomed in 100%. This will give you a strong sense of what the mask and subsequent adjustments do.

Select Sky mask: Lower part of tree by horizon

After choosing Select Sky in the Mask menu, I viewed the lower part of the Joshua Tree, near the horizon, at 100% view.

The Sky Selection mask on a particularly challenging low-light scene with a spiky Joshua Tree.
The Select Sky mask on a particularly challenging low-light scene with a spiky Joshua Tree.

The Select Sky mask selection for the sky appears in red. If you look at the shorter Joshua Trees by the horizon, you’ll notice that the sky is not masked between the two short Joshua Trees, among several other places.

The long slender spines have caused some problems. However, you can easily click the Add button, select Brush, and then paint more of the mask selection there.

Adjustments

Now, it was time to make some adjustments. These adjustments are primarily to showcase how much Lightroom’s mask selection affects the overall image. In some cases, I’ve lowered the exposure by a substantial amount to exaggerate what the mask is doing.

To establish a visual baseline, this is what the zoomed-in scene looks like with no adjustments of any kind, followed by exposure adjustments of -1 and -2. As I decreased the exposure, you can see that the aforementioned areas are considerably lighter.

I also went the opposite way to see what happened. I raised the exposure by +1.

I've raised the exposure by +1.00. While the selection is not as obvious, you can see that the coloration in some of the unmasked areas are already slightly different.
I’ve raised the exposure by +1. While the selection is not as obvious, you can see that the coloration in some of the unmasked areas are already slightly different.

Select Sky mask: Upper part of tree

Just to be thorough, I created some screenshots of the mask selection at the upper part of the Joshua Tree. These are also zoomed in at 100% so you can see what the Select Sky mask is doing.

Looking at the upper Sky Selection Mask at 100% view. This is a challenging low-light scene with a spiky Joshua Tree.
Looking at the upper Select Sky mask at 100% view. This is a challenging low-light scene with a spiky Joshua Tree.

Again, the mask selection for the sky appears in red. You can see that between the branches and spines near the top, the sky is not masked, among several other places. You could again easily click the Add button, select Brush and then paint more of the mask selection there. This would be quite easy to do.

To establish a visual baseline, this is what the zoomed-in scene looks like with no adjustments of any kind, followed by exposure adjustments of -1 and -2. As I decreased the exposure, you can see that the unmasked areas are considerably lighter.

I also went the opposite way to see what happened. I raised the exposure by +1.

I've raised the exposure by +1.00. While the selection is not as obvious, you can see that the coloration in some of the unmasked areas are already slightly different.
I’ve raised the exposure by +1. While the selection is not as obvious, you can see that the coloration in some of the unmasked areas are already slightly different.

More typical subtle adjustments

Ordinarily, I would click the Add button and then brush in the areas that missed. But for the sake of experimentation, I decided to create some typical subtle adjustments that one might do.

I've created some subtle adjustments here. I lowered the exposure by -0.34, just to make the sky appear more like a night sky. I've also applied +15 of noise reduction. I actually have the sharpen adjustment at +3, which is minute. This was actually supposed to be -3, but apparently I bumped it while creating the screen shot.
I’ve created some subtle adjustments here. I lowered the exposure by -0.34, just to make the sky appear more like a night sky. I’ve also applied +15 of noise reduction. I actually have the sharpen adjustment at +3, which is minute. This was actually supposed to be -3, but apparently I bumped it while creating the screenshot.

Above, I’ve applied subtle adjustments. I felt like the Select Sky mask was adequate for these relatively typical adjustments that one might make to a night sky.

If I had decided to brush on more of the Select Sky mask to correct the mask more, I could obviously do less subtle exposure changes. However, the idea was to test what Lightroom Classic was selecting automatically.

A very quick look at the Select Subject mask

Without getting too much further in the weeds here, I thought I would show you what the Select Subject mask looked like on the upper part of the Joshua Tree.

 Lightroom Select Subject mask on a very dark Joshua Tree.
Lightroom Select Subject mask on a very dark Joshua Tree.

You can see some of the problem areas where it selected parts of the sky. These areas were in many of the same areas that plagued the previous mask.

Again, this is very easy to correct. And even if the selection is not perfect, it is still worth doing because it gets you considerably farther along than you were before. You can use the brush to correct these easily.

Additional thoughts

After correcting the mask by using the brush, I was able to apply a little bit of noise reduction to the sky and lower the exposure a little.
After correcting the mask by using the brush, I was able to apply a little bit of noise reduction to the sky and lower the exposure a little.

Even on a very dark and challenging night photo with a difficult subject, Lightroom Classic’s Select Sky mask interpreted most of the sky correctly.

Even if the selection is incorrect, I feel like it is worth doing because it gets you so much farther than you might have done by using a brush. And you could further address some of the masking with other mask options, such as Luminosity or Color masks, just some of their other options.

I’m rather pleased that this is one of the tools we can use for selecting specific areas.