Creating Affinity Photo Luminosity Masks

If you’ve come from a Photoshop background, creating Affinity Photo Luminosity Masks could have you scratching your head. If you Google Luminosity Masks and Affinity Photo, you’re likely to find a couple of things:

  1. A simple approach to creating Luminosity Masks in Affinity Photo using the Select Tones option. You may even find one of my videos showing you how to do this.
  2. People arguing that you don’t need to create Luminosity Masks in Affinity Photo because of the advanced Range Blending options.

The first of these approaches is simple but doesn’t give the control possible in Photoshop. And the second option is brilliant but isn’t really a replacement when you just want to reproduce what’s possible in Photoshop.

I won’t get into an argument over the validity of using Affinity Photo Luminosity Masking in this article. Instead, I will show you how to create sets of Luminosity Masks, just as you might in Photoshop. Best of all, I’m going to show you how to do it without needing to remember lots of complicated keyboard shortcuts.

If you find the description a little difficult to follow, I’ve produced a full video demonstrating the process. You’ll find this later in this tutorial, but before you scroll down searching for it, it’s still worth reading the text.

Creating the Lights Luminosity Masks

The first and most complicated task is to create our Lights 1 mask. This luminosity mask will form the basis for all the other masks and is just a black and white version of the image.

To create the initial black and white image, open your photo in Affinity Photo. Now duplicate the Background layer in the Layers panel. You can do this by selecting the layer and pressing Command + J (Mac) or Ctrl + J (PC) on your keyboard.

Click the new duplicate layer to select it, then click the Adjustment Studio Panel.

In the Adjustments panel add an HSL adjustment layer. In the HSL dialog, reduce the Saturation slider for the Master Channel to 0, desaturating the image.

Try to avoid the urge to use a Black and White Adjustment Layer to create the black and white image. The colour response sliders can affect the results. I’ve personally found the HSL method typically produces a better result.

In the HSL layer, click the Merge option. This will merge the adjustment with the currently selected layer. The result is that the layer you created will have the saturation removed, creating the Lights 1 layer which you can see below.

Saving the Luminosity Mask as a Channel

Now it’s time to save our image as the Lights 1 Luminosity Mask. Fortunately, Affinity Photo provides a very easy way to do this in the Channels Studio Panel.

At the top of the Channels Studio Panel, you will see the “Composite” channels. If you click on the Red, Green or Blue composite channels you will find they are all identical. That’s because there’s no colour in the image, making all the colour channels the same. You can see the channels indicated with a number 1 in the following screenshot.

When you right click on one of the three composite channels you will see a popup menu. Click the option to “Create Spare Channel”. This will save a copy of the channel you selected with the name “Spare Channel”.

Right-click on this new channel which appears at the bottom of the Studio Panel and rename it “Lights 1”. You can see this numbered 2 in the screenshot.

Creating the other Lights Luminosity Masks

Now we have our Lights 1 Luminosity Mask saved we can create the Lights 2 mask. To do this, duplicate the desaturated layer you created in the Affinity Photo Layers Studio Panel. You can do this right clicking the layer and selecting the Duplicate option.

Alternatively, you can click the layer in the to select it and then press Command + J on your keyboard (Mac) or Ctrl +J (PC).

Select the new duplicate layer by clicking it and change the Blending Mode from “Normal” to “Multiply”. You will now see the image becomes darker.

Back in the Channels Studio Panel, right-click one of the Consolidated channels as you did before and create a Spare Channel.

Rename the spare channel to be “Lights 2”.

The process to create the Lights 3 Luminosity Mask is just a repeat of Lights 2.

Create a new duplicate layer in the Layers Studio Panel. This time you won’t need to set the Blending Mode if you duplicated the layer that you set to Multiply.

Now go over to the Channels Studio Panel and save the Consolidated channel to be Lights 3.

You can continue this process until you have all the Lights Luminosity Masks that you need.

Once you’ve finished, delete all the layers you created except for the first “desaturated” layer.

Creating the Darks Luminosity Masks

To create the Darks series of Luminosity Masks is very similar to the Lights series. The only difference is that we first need to invert our desaturated layer.

You can invert the Layer by clicking to select it. Then in the Adjustment Studio Panel click the “Invert” adjustment.

Unlike other Adjustment Layers, this adjustment doesn’t have a dialog. Instead, if you check the Layers Studio Panel you will see a new Invert adjustment layer. If you right click this layer to display the popup menu, you can select the “Merge Down” option. This merges the layer with the one below it.

You can now save this as a Spare Channel in the Channels Studio Panel, calling it Darks 1.

To create the remaining Darks Affinity Photo Luminosity Masks the process is the same as for the Lights series.

In the Layers Studio Panel duplicate the inverted layer and set the Blending Mode for the new layer to “Multiply”. You can then save this as a Spare Channel in the Channels Studio Panel, calling it Darks 2.

Repeat this process until you have a complete set of Darks Luminosity Masks.

You can then delete all the layers you created as we won’t need them.

Creating the Midtone Luminosity Masks

To create the Midtone Luminosity Masks is now very quick.

First, select the entire image. You can do this using the keyboard shortcut Command + A (Mac) or Ctrl + A (PC).

In the Channels Studio Panel right-click on the “Lights 1” channel that you saved. In the popup menu select the option “Subtract From Pixel Selection”.

Next, right-click on the “Darks 1” channel and select the option “Subtract From Pixel Selection”.

What you’re left with is a selection of the midtone pixels in the image. You can save this as a Spare Channel by right-clicking on the “Pixel Selections” option in the Channels Studio Panel.

Rename the new spare channel to be “Midtones 1”.

You can now repeat this process for each of the Lights and Darks mask pairs until you have created all the midtone masks.

You now have a complete set of Affinity Photo Luminosity Masks.

Watch the Affinity Photo Luminosity Mask Video

Some of the instructions in this tutorial may not seem clear at first. To help you I have produced a video about creating Affinity Photo Luminosity Mask which you can watch below.

Subscribe to my YouTube Channel

You can also watch this video on my YouTube channel. I publish a new video every week, often based on subscribers’ requests and feedback. Subscribe to my YouTube channel now and be sure not to miss future videos.

Summary

Creating Luminosity Masks in Affinity Photo can seem a little confusing if you’re used to working in Photoshop. But by following the instructions in this tutorial and watching the video you should see be able to follow the process. As for the question is this necessary, I’ll address that in another article in the future. For now, this method for creating Luminosity Masks should help anyone feeling they need to.

If you would like more of an introduction to Affinity Photo editing, see my book below.

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Photo Editing Tutorials Affinity Photo Luminosity Masks