Refine Luminosity Mask In 5 Simple Ways

By YaopeyLuminosity masks, Tutorials

Why do you need to refine luminosity mask?

Because sometimes you just can’t get the luminosity mask that fits for your editing.

What do you do?

Do you give up and blame the image? (in this case, the image becomes the scapegoat for being difficult)

Or persevere and fight till the end.

Refining a luminosity mask is easy. You either increase the contrast to separate the highlights and the shadows more, or you fill in white to the mask. You can also use Refine Mask in Photoshop to refine luminosity mask.

If nothing has made sense to you so far, you can learn more about how luminosity masks work in this article.


Refine Luminosity Mask

Luminosity masks use luminance of the pixels to make a selection.

The selection may not always be restricted to the area you want because other parts of the image may have similar luminance and it gets included into the selection.

The easiest way to fix this is to group the layer (yes, you can group a single layer!) and apply a layer mask to the group to mask out the area you don’t want adjustments.




In other times, you get the perfect luminosity mask that covers the selection but the strength of the mask isn’t strong enough (not 100% or near 100% white). Because of that, your adjustment isn’t being revealed as much.

original image and brights 3 luminosity mask
Original image on the left and brights 3 luminosity mask on the right.

If you look at the example image above, I wanted to brighten up the clouds in the background to make it pop.

The only luminosity mask that isolates the clouds perfectly is brights 3, but the selection isn’t white enough. This means any adjustments won’t be revealed much to have a good effect.

Once I’ve refined the brights 3 luminosity mask, the adjustment shines through with excellent result. You can see the before and after image below.


Increase The Contrast of The Mask

One of the ways to refine luminosity mask is to apply a Levels or a Curves adjustment directly onto it.

An increasing contrast makes the bright brighter and the dark darker. You can utilize this principle to refine luminosity masks in Photoshop.

In this image below, I want to increase the contrast in the sky but I don’t want to affect the building especially the shadows.

low contrast image
Original image without any adjustments

Now compare the brights 1 and the brights 2 luminosity mask, brights 2 isolates the sky better (because the building is almost excluded) but the luminance of the mask in the sky isn’t great.

bright 1 and brights 2 luminosity masks
Comparing brights 1 mask and refined brights 2 mask

So here’s how you can refine the mask to optimize for the sky:

  1. Go to the Channels panel and click on brights 2 (you don’t need to cmd/ctrl + click to select).
  2. From the menu on top, choose Image > Adjustments > Levels / Curves (or use keyboard shortcut cmd + L (Levels) or M (Curves).
  3. Apply contrast to make the sky brighter and the building darker on the luminosity mask.
  4. Now cmd / ctrl + click to select the now refined luminosity mask and apply your adjustment.


The above before and after is to compare how the image looks with a brights 1 luminosity mask (before) and a refined brights 2 luminosity mask (after). You can see the contrast and the shadows of the building is not affected in the “after” image.


Increase The Contrast of The Image

If you don’t like the idea of applying tonal adjustments to a luminosity mask, consider this instead. Similar to the first method, you increase the contrast but this time to the image to separate the highlights and the shadows even more before creating luminosity masks.

increase contrast on image to refine luminosity mask
Increase contrast on the image first before generating luminosity masks

Now check out the brights 2 luminosity mask from the first method and the brights 2 luminosity mask from this method.

comparison both bright 2 masks
Comparing brights 2 luminosity masks in both methods

As you can see, the masks look almost identical. If you look closely, the brights 2 mask in this method is greater, which means the building is going to get even less affected after tonal adjustments for the sky.


Filling In A Mask With White

Another way to refine luminosity mask without messing about with the contrast is to increase the luminance of the selection. The principle is the same as the above 2 methods – to increase the contrast of the mask, especially within the selection.

Back to our example image. I’m going to use the brights 2 luminosity mask again. This time, we create luminosity masks without applying levels/curves adjustment to the image or the mask itself. Select the brights 2 mask from the channels panel and apply it to a levels adjustment.

Here’s what you do next:

  1. Hold down opt (Mac) or alt (Win) + click on the layer mask loaded with brights 2 luminosity mask.
  2. Your image will turn into a grayscale of the layer mask – mask view.
  3. Make sure the selection for brights 2 luminosity mask is active. If you deselected the selection already, hold down cmd (Mac) or ctrl (Win) + left click on the layer mask itself. This will bring back the marching ants. Hide it with cmd or ctrl + H if you like.
  4. To increase the luminance of the selection, you need to fill the selection with more white. Use the keyboard shortcut Shift + Backspace to bring out the fill panel. Choose White in Contents and press ok. You will see the luminance of the selection has increased (becomes whiter).
  5. Switch back to the normal view of your image to see how the effect looks.
  6. Repeat Step 4 until you are satisfied with the result.


filling in mask to refine luminosity mask
Filling brights 2 selection with white each time

Comparing the image with the original brights 2 mask without any refinement (before) and the bright 2 mask filled with white (after). In this case, I’ve only filled in white to the mask once.


Painting A Mask With White

Similar to filling in a mask. Now you just paint them in.

What difference does it make? I find painting a mask to have more control over where in the selection I want to have more luminance (revealing more adjustments underneath).

Going back to our brights 2 luminosity mask. Similar to filling in a mask, you select the luminosity mask from the channels panel first without changing its contrast.

Curves adjustment applied with a painted brights 2 luminosity mask

In the Layers panel:

  1. Opt / alt + click on the layer mask to view mask in the image area.
  2. Make sure the selection is still active. If not, reactivate the selection by cmd / ctrl + click on the layer mask. You should see marching ants again.
  3. Select the brush tool and change the color to white. Keep hardness to 0% and start with an opacity of 50%.
  4. Paint white into the area you want the effect to be stronger.
  5. You can increase the opacity of the brush to add more adjustment in a single pass.


painted white refine luminosity mask
White was painted into the selection in the brights 2 luminosity mask

Painting in a mask is a bit like dodging and burning. You apply white into where ever you want in the selection on the luminosity mask to reveal more.


Use Refine Mask In Photoshop For Further Fine Tuning

This is Photoshop’s built-in tool to refine layer mask. You can use this to refine luminosity mask or as a tool to further refine the mask after one of the above methods. I don’t usually start with this because it doesn’t give you much control like all other methods above.

refine mask panel
Use Contrast and Shift Edge to further refine luminosity mask


With Refine Mask, I often use Contrast and Shift Edge to isolate my selection even more.

  1. Load your luminosity mask onto the layer mask of the adjustment layer.
  2. Opt / Alt + click on the mask to go into mask view.
  3. Open Refine Mask by either from the menu on top, Select > Refine Mask or click on Refine Mask in the layer mask’s properties panel.
  4. Use Contrast and Shift Edge to refine luminosity mask.
  5. Click OK when you’re done.



As you can see, there isn’t a single way to refine luminosity mask.

The result of each method is very similar as you can see. So pick a method you like but keep others in mind just in case your method of choice doesn’t work in challenging situations.


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