My editing workflow: Luminosity Masks

In this blog I start disclosing my editing workflow and the first topic I’d like to introduce is Luminosity Masks.

Luminosity Masks is something you might have heard before, particularly if you shoot landscape/cityscape. In a nutshell, they are selections based on tones that allow for specific adjustments.
In their basic form, they target broadly highlights and/or shadows. But they can be further refined to include midtones or narrow down to the brightest and darkest areas of an image.

Here I’ll mention Adobe Photoshop almost exclusively.
I suppose you can achieve the same results in Affinity Photo but I don’t know enough about it. Lightroom CC recently introduced a similar functionality (range) but less customisable.

Despite being such a powerful tool, Luminosity Masks are still seen as daunting and not many photographers use them. I suppose one of the reasons is that they’re created manually and there’s no button or menu item for them. But you can find third party solutions to help you create them, and I use a couple myself.
Perhaps they’re considered too tedious as well. Why would someone go such a long way only to create a selection?
Well, I do go such long way. And quite often as well. So let’s see if I can convince you here.

Quick intro to creating Luminosity Masks

As I mentioned, the basic Luminosity Masks target highlights or shadows. They are fairly easy to create from the Channels panel:

  • Cmd/Ctrl + click on the RGB thumbnail in the Channel tab;
  • Save the selection (Select > Save Selection or click the Save Selection icon in the Channels tab);
  • Cmd/Ctrl + D to deselect.

That’s it! Your first Luminosity Mask based on the highlights.

Bonus Tip: if all you need is a quick selection of the highlights, simply hit Cmd/Ctrl + Opt/Alt + 2 and Photoshop will make it.

Now you can quickly make another selection for the shadows: duplicate the channel you just created (right click on that) and then invert it with Cmd/Ctrl + I.
Remember to rename your channels so you don’t get confused, particularly if you create more. Highlights 1 is your first, Shadows 1 the duplicate. The number 1 in the name will help later when refining.

But what about midtones? Well, it’s a bit less straightforward but it’s quick once you created the Highlights 1 and Shadows 1 channels:

  • Hit Cmd/Ctrl + A to select the entire image;
  • Cmd/Ctrl + Opt/Alt + click on the Highlights 1 thumbnail;
  • Cmd/Ctrl + Opt/Alt + click on the Shadows 1 thumbnail (if you get a warning “no pixels are more than 50% selected” you can ignore it);
  • Save the selection and name it Midtones 1.

What we’ve done here is subtract Highlights and Shadows from the image, leaving us with the midtones πŸ™‚

Kyoto Golden Pavillion (luminosity masks tutorial image, midtones)

To refine the Luminosity Masks, follow the same subtraction process.
Take for example the Highlights:

  • Cmd/Ctrl + click on the Highlights 1 thumbnail;
  • Cmd/Ctrl + Opt/Alt + Shift + click on the same thumbnail;
  • Save the new selection and name it Highlights 2.

So on and so forth. You get the point πŸ˜‰

Use of Luminosity Masks

Now that you know how to create Luminosity Masks, let’s see how you can use it.

The whole process above is merely a way to create selections. You haven’t applied any change to the image yet. You still need to go through the usual changes you’d apply: Curves, Levels, etc. But now you have a very precise selection of the areas you wish to enhance.
Also, always remember that “white reveals, black conceals”: the brightest areas of the masks are those where the effects will be visible. Just looking at the channels you created will give a clear idea of the areas impacted.

Let’s start by taking the highlights as example again.
This is one my shots, straight out of camera, from Kinkaku-ji in Kyoto.

Kyoto Golden Pavillion (luminosity masks tutorial image)

Notice that here the sky is overexposed. An easy fix is to create a new Curves adjustment layer (aka Curves in a non-destructive way) and try to darken the sky.

Kyoto Golden Pavillion (luminosity masks tutorial image)

But to retrieve colour and detail in the sky we have darkened the whole image! Oh no!

Now let’s create our basic Luminosity Mask for the highlights. After we save the new channel hit Cmd/Ctrl + click on it to activate the selection. Then let’s move to the image, mask the layer and apply the Curves fix again.

Kyoto Golden Pavillion (luminosity masks tutorial image)

That’s much better. The adjustment only applies to the sky, leaving the rest of the image untouched.
Now that you know how to do it, don’t you find it very fast and easy?

Let’s see if we can do something to the shadows as well…
Creating another Luminosity Mask, for the shadows, we are able to selectively change the colours to eliminate the yellow cast over the image (subtle, I know).

Kyoto Golden Pavillion

Now this is becoming interesting.

What’s next?

We only scratched the surface here. Once you start using Luminosity Masks, it becomes very easy to start experimenting with them.
And you’re not limited to recovering highlights and shadows with Curves: you can use all sorts of adjustments with this method. Solid colours, photo filters, hue and saturation, levels, colour balance… You can apply them to everything you already use in Photoshop.

But my favourite application of Luminosity Masks by far, is blending multiple images together.


This will likely require a full tutorial on its own, but let’s briefly talk about it.
Often when I shoot landscapes and cityscapes I shoot multiple images of the same subject, tweaking the exposure at every shot. It’s a process known as bracketing, and most cameras nowadays offer this function at the push of a button.
This is useful because cameras aren’t always capable of showing the entire dynamic range of a scene into a single shot. So, often I do this to have a broader dynamic range to work with.
It’s the exact same idea behind HDR photography (HDR stands for High Dynamic Range) which is even available in smartphones now.

Using Luminosity Masks though, you can make a lot more refined adjustments and use only the best bits of each shot. And since they can be applied to as many layers as you wish, there is room for great enhancements.

Let’s see a quick example:

Showing three bracketed shot to illustrate how Luminosity Masks work.
A darker shot for the sky, a base shot for the main subject and one lighter for the foreground.

Assuming you shot bracketed with your default settings in camera, you should have 3 photos of the same subject: one base image, one darker and one brighter.
If you didn’t use a tripod, first align your images using Edit > Auto Align Layers (leave the settings as they are). This should align your shots correctly, probably leaving some empty areas around the edges that you’ll have to cut out. You shouldn’t have this problem when using a tripod.
Create your luminosity masks following the instructions above. Then, apply the Highlights 1 to your darker shot and Shadows 1 to the brighter one.

Depending on your image, this might require some further refinement. But you just quickly recovered details from shadows and highlights without tweaking the exposure that could have possibly introduced noise or artifacts.
And it’s a much more controlled way to apply HDR-like enhacements to your photos.

Wrapping up

This is my introduction to Luminosity Masks. I use this method extensively in my editing workflow, particularly to blend multiple exposures.
Hopefully I explained it clearly enough to inspire you to start using them too.

But if you want to take an even faster approach, I am preparing an Adobe Photoshop action to let you create Luminosity Masks with a single click.
I will add a form below here so you can add your email and receive that in your email inbox.
Just bookmark this page and come back. If you subscribe to the newsletter, it’s very likely that you’ll see an announcement there πŸ˜‰

And that’s it for my first editing workflow tutorial. Hope you enjoyed it.

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