- Hi, I'm Jan Kabili, and this is Photo Tools Weekly. Our subject this week is luminosity masking in Photoshop. Luminosity masking is a term you may have heard of, but maybe you're not exactly sure what it is or how to do it. I'm going to try to simplify that for you, but this is a pro technique. So you'll need to understand the basics of Photoshop masking and channels to get the most out of what I'll be showing you here. The goal of luminosity masking is to give you a way to fine-tune your photo adjustments by applying adjustsments to areas of particular brightness values.
In a nutshell, here's how it works. You'll create luminosity masks as channels in your Channels panel. If you record the steps of creating a luminosity mask as an action, as we'll do in this movie, you won't have to go to the trouble of manually creating luminosity mask channels in other photos that you want to adjust. You can just run the action you've recorded on other photos to generate luminosity mask channels for them automatically. Then, you can put those luminosity masks to work to target particular tonal values to adjust using editing features with which you may be familiar, like adjustment layers.
The first step is to record everything that I'm about to do as an action. I'll go to the Actions panel, and I'll click the Create New Action button. I'll name this Luminosity Masking, and I'll click record. Now, everything that I do from here on will be recorded in this action. So I need to work in a particular order. I'll go to the Channels panel. If you're following along, your Channels panel may not be here. It may be in the same panel group as your Layers panel. I just dragged those panels apart so I can see them both. I'll start making my first luminosity mask channel by loading a selection of the highlights in this photo.
To do that, I'll hold down the Command plus Option keys on a Mac, the Control plus Alt keys on Windows. And I'll click right on the thumbnail of the RGB color channel. The marching ants in the document Window represent a selection of the highlights in this photo. Next, I'll use this selection to make a new channel. I'll leave this selection active as I go to the bottom of the Channels panel to the second button from the left. The official name of this button is the Save Selection as Channel button, but I like to call it the washing machine button because that's what it looks like, and it is easier to remember that way.
So I'll click my washing machine button, and that saves my highlights selection as a new channel. This kind of channel is called an alpha channel. That just distinguishes it from the other kinds of channels in the Channels panel, these color channels. An alpha channel contains a mask represented by the thumbnail on the alpha channel. This mask is made up of black, white, and gray areas. The whites in the mask represent the areas I had selected, the highlights. The blacks represent the unselected areas, the shadow areas of the photo, and the grays represent partially selected areas in between.
One way to think of this is that a selection and an alpha channel are just different ways of displaying the same thing. Now, with my selection still active, I'm going to go the bar of my alpha channel and click on it, and then I'll name this alpha channel by double clicking right on the Alpha One name. I'll name this Highlights. It's important that I leave this selection of highlights active as I go on to make another luminosity mask channel. To do that, I'm going to hold down a combination of three keys, Command plus Option plus Shift on the Mac.
That's Control, Alt, Shift on Windows. And I'll click right on the thumbnail on my Highlights channel. That creates an intersection selection, a selection of brighter highlights inside that first selection I've made of broader highlights. So this selection is a more restrictive one than the last selection. I'm going to convert this selection to a second alpha channel, again, by going to the bottom of the channels panel and clicking the washing machine button. There's my new alpha channel. I'll select it by clicking on its bar, and then I'll double click its name.
And I'll give it a more meaningful name. These are my brighter highlights. Again, it's important to leave this selection of the brighter highlights active as I go on to make another luminosity mask channel of even brighter highlights. And, remember, all this is being recorded, So, if you're following along, continue in the same order that I am. Again, I'll hold down Command plus Option plus Shift and click on the thumbnail on the Brighter Highlights channel. That creates this intersection selection, a selection of even brighter highlights than last time, an even more restrictive selection if you want to think of it that way.
I'll convert this selection to a third alpha channel, again, by going to the washing machine icon at the bottom of the Channels panel and clicking it. There's my new channel. I'll select it by clicking on its bar, Then, I'll double click on the name Alpha 1. and I'll name this Brightest Highlights. By the way, if you're wondering why I'm using the words Brightest Highlights to name this channel, even though this channel has the most dark areas of all the channels I've created so far, you would have to remember how masks work. In a mask, like this alpha channel mask, white corresponds to the area that's selected, and black corresponds to the area that was not selected.
And when I made this third channel, I had the most restrictive selection of just the brightest parts of the photo selected. Therefore, the mask on this third channel has the least amount of white, and its white areas represent only the very brightest parts of the photo. And, so, that's why I named it the Brightest Highlights channel. Now, I'm going to deselect. I'll press Command D on the Mac or Control D on a PC. And I'm going to go up to the RGB channel and click on it because I'm going to start a new series of alpha channels, a series that represents the dark areas of the photo.
I'll do all this the same way, except I'll use selections of dark areas. I'll start by holding down Command plus Options, that's Control plus Alt on Windows, and clicking directly on the thumbnail of the RGB channel to select the highlights again. And, then, I'll invert the selection so that I've selected not the highlights but the shadows. To invert this selection, you can use the keyboard shortcut Shift, Command, I on Mac or Shift, Control, I on Windows, or go up to the Select menu and choose Inverse.
I'll save this selection of shadows as an alpha channel by going back to the channels panel and clicking the washing machine icon. I'll select my new alpha channel by clicking on it, and you can see it here in the document window. All of this light area represents the shadows in the image. I'll double click the name of this channel, and I'll name it Shadows. I'll leave my selection active. I'll hold down Command, Option, Shift, and I'll click on the thumbnail of the Shadows channel. That creates a more restrictive selection of even darker shadows.
I'll make this into another alpha channel by, again, clicking the washing machine icon at the bottom of the Channels panel. I'll select the new alpha channel. I'll double click its name, and I'll call this one Darker Shadows. Again, it's important to keep the selection active as I make my last alpha channel, an alpha channel for the darkest shadows. I'll hold Command, Option, Shift. I'll click on the thumbnail on the Darker Shadows channel. I'll make a new channel from this selection by clicking the washing machine icon, and I'll select the new alpha channel, double click its name, and name it Darkest Shadows.
I've made six alpha channels representing different degrees of brightness. You can make even more dark and light channels the same way if you like. But I'm going to stop there. So I'll deselect. That's Command, D on the Mac or Control, D on Windows. And I'll go back up to the top of the channels panel, and I'll click on the RGB channel there. Now, remember, I've been recording an action this whole time. So, now, it's time to stop the action. I'll open the Actions panel, and I'll click the Stop Recording button. So that's how you can create a set of luminosity masks, which you see here in my Channels panel.
There are a lot of steps, but many of them are repetitive. And the good news is that once you record the steps as an action, you won't have to do them again. You can just play the action on any photo that you want to correct and Photoshop will make the same number of luminosity channels in that other photo. But making the luminosity masks is not all that I have to show you. The whole point of making these masks is to that you can use them to target image adjustments to particular brightness areas of other photos. And that's what I'll show you how to do in the very next movie.
So stay tuned for the second part of Photo Tool Weekly's coverage of luminosity masking.