How to Make Selections Based on Channels in Adobe Photoshop

I’ve been trying to avoid channels in Adobe Photoshop for years and years. I’ve heard about them, seen them and have even messed around with them a bit, but have never appreciated them in the least. It seems that every time I visited the Channels panel in this application, I pressed something that made everything look screwy. After that, I ran for the hills. I went back to the trusted Layers panel and got on with my work. I’ll admit that I was scared of channels because I didn’t know what to do with them. They were in unfamiliar territory and because of that, I never really appreciated all the power they possess. Well, you know what? No more. From here on out, I’m going to tackle channels head on and I’ll even bring my learnings to you.

In today’s post, I’m going to venture into the Channels panel in Adobe Photoshop. I’ll start off by giving you a very brief primer on what color channels are and then I’ll show you a hugely helpful tip on how you can create a selection based on a specific channel. Finally, I’ll alter that selection by applying an adjustment layer to it. You don’t need to know anything about the long history of channels (they were in existence before layers) to enjoy this post. All you need to know how to do is to push a few buttons and make a couple of clicks with your mouse to get something out of what I share. I really do think you’ll appreciate it.

Today’s Demo Photo

I think this might just be the perfect image to use for what I’d like to show you today. It’s got such nice color separation. It’s not going to be difficult at all making the selections I’d like to make.

What are Color Channels?

There are different types of channels, but to keep things ultra simple, I’m only going to discuss one type; color channels. And even then, I’m going to leave a lot of information out. From what I’ve learned, people lose interest in these things very quickly when they’re inundated with information about them. Because channels are so useful and powerful, it would be a shame to make you roll your eyes and click off this page, simply because I decided to show off how much there is to know.

Anyway, let’s get going. In Photoshop, channels are separate grayscale images that contain different types of information. Each cluster of information is stored in an individual channel, or container. The type of channels we’ll be dealing with today are called color information channels, or color channels. These are things that are created automatically when you open a new image inside of Photoshop. The reason you don’t see them right away is because the panel they’re held in either isn’t opened by default or is tucked away behind the Layers panel.

When you open an image, the channels are created, but they’re created based on what color mode the image has initially been created in. RGB images (for the web) contain three channels (red, green, blue), plus an overall composite RGB channel and CMYK images (for print) contain four color channels, plus a composite one. Images in Lab color mode contain three channels, plus a composite and images in Multicolor mode contain three total channels. Let me show you what I’m talking about with this RGB image I just opened up in Photoshop.

If I click on the Channels tab that’s next to the Layers panel tab, I’ll see the channels in question. If that panel isn’t available, I can just as easily head up to the Window > Channels menu item and click.

Once the panel is open, I’ll see the composite I was talking about, plus the other three individual colors.

Treat each color as a film or a layer. Separately, they only contain their respective colors, but combined, they make up the full color image. Also, we’re seeing these thumbnails right now in color. We can also see them in black and white if we wish. To see them in that view, I can visit the Edit > Preferences > Interface menu item and uncheck the Show Channels in Color option.

When I do that and click the OK button, I’ll see the color in each individual color channel disappear and turn black and white.

If you look at the channel thumbnails closely, you’ll see black, white and gray areas. The black areas are those that don’t contain that specific color, the white areas contain that color completely and the gray areas contain some of that color. So if an image was completely solid red, the red channel would be totally white and the blue and green would be black.

For the time being, I think I’ll keep the channels in black and white mode. I can see things more clearly this way.

Making a Color Selection via a Channel

This is so cool. You’re going to love it. Let’s say that I wanted to alter this demo image somewhat. I’d like to get rid of a lot of the blues and greens and accentuate the red contents of the glass that’s sitting on the beach. To do this channel by channel, it wouldn’t be difficult at all. To start off with, I’ll make a selection. I think I’ll select the blues first. I’ll click on the Blue channel to make it active so I can see things better in the actual image itself and then when I’m sure that it’s the one I would like to make my selection in, I’ll hold down the Ctrl (Command on Mac) key and click once on the channel thumbnail. Doing this will select all the blues in the image. Take a look at the marching ants.

The above screenshot is a bit deceiving. It appears that the glass is selected. In actuality, almost everything is selected but the glass.

Okay, so that’s how you can make a color selection via the Channels panel. In the next section, I’ll do this and add some adjustment layers as well.

Adding an Adjustment Layer for Each Selection

To create the effect I’m after, I’ll first select the blues from the Blue channel. Then, once I see the marching ants, I’ll click back into the Layers panel so I can see what I’m doing. After that, I’ll click on the Hue/Saturation icon up in the Adjustments panel.

Finally, I’ll push the Saturation slider in the Properties panel all the way to the left to remove as much saturation as I can. So, from the above screenshot, you can see that a new adjustment layer was created, the Properties panel was opened up and that I pushed the Saturation slider to the left. Let’s take a look at the resulting image.

Next, I’ll follow the same exact steps for the Green channel and then again for the Red. For the Red channel though, I’ll push the Saturation slider slightly to the right to increase that color a bit. In all, I’ll have made three selections; one for each channel. After making those selections, I’ll have created three different Hue/Saturation adjustment layers that will have reduced the saturation of the blues and greens and increased the saturation of the reds. Let’s take a look at the final image.

See? Pretty cool, right? Honestly, when was the last time you made a selection from different channels in the Channels panel? I’m guessing it was either a long time ago or maybe even never. You learn something new every day! And if you think about it, you can take this concept and apply it to about a million different things. It’s so versatile.

I hope I clearly explained how to work a little bit inside of the Channels panel in Adobe Photoshop. You should now know how to make a selection from a specific color channel and how to apply that selection to create an effect by way of adjustment layers. If you have any questions regarding this post, please let me know in the comment section below. You may also ask questions in my new discussion forum. Thanks for reading!