In this Photoshop tutorial I will show you how to cut out complex objects from the background using the Channels panel. (Channels) and the calculation function (Calculations)... This method of extracting objects from the background is very convenient because it saves a lot of time, unlike using other selection tools.

Let's look at the effect of this technique in practice and see for ourselves.

Why use channels to mask the image?

Photoshop offers different selection tools: magnetic lasso, magic wand, quick mask, etc ... why use channels for this purpose? The point is that using channels will save you a lot of time and make your work more accurate.

For most users of the program who are engaged in retouching photos and processing their pictures and pictures of friends, it is difficult to understand that the "Channels" palette can be used to create a Layer Mask (Layer Mask)because they just don't know what it is.

I will not explain what channels are, this is a topic for a separate lesson, but let me remind you that channels divide the image into three different levels of brightness, corresponding to three colors red, green and blue. (Red, Green, Blue), which is RGB mode. Let's look at the action of channels in this lesson.

Here is the selection result we should get:

Step 1.

Open in Photoshop the image of a tree branch on a blue background from the resources of the lesson and duplicate it (Ctrl + J)... Rename the duplicated layer "Branches". On this layer we will create a Layer Mask (Layer Mask)to hide the blue background on it by cutting out a branch from it.

Step 2.

You know that you could highlight the branches in the background with the Pen (Pen Tool) or Magic wand (Magic Wand), but this selection technique will take a lot of time, effort and will lead to the formation of jagged edges of the object. Using the Quick Mask (Quick Mask) also a rather troublesome task in our case.

Since we have a uniform background, it is appropriate to apply the selection method using alpha channels. Even if you don't understand anything yet, just follow all the steps with me in order and everything will become clear.

On the Branches layer, go to the Channels panel (Channels)located next to the Layers panel (Layers)by clicking on its tab.

Step 3.

You see in the opened palette three layers of channels for each of the three primary colors of the image: red, green and blue. (Red, Green, Blue)which are called alpha channels. The top layer of the "RGB" channel is a combination of all three alpha channels at the same time.

For a high-quality selection of an object, we need a channel that will have the best contrast between the background and the branch. Go through all three channels one by one and choose the most contrasting one. In our case, the best option would be blue (Blue) channel, because the contrast is stronger between the background and the branch here than in the other two.

Click on the blue channel to activate it.

Step 4.

With the blue channel selected, go to the Image-Calculations menu (Image\u003e Calculations)... This function will help us blend the alpha channels and show a preliminary result. Using the Calculate tool (Calculations) we will create a new alpha channel based on the three existing ones. Complete the settings from the screenshot below:

Let me explain what happens to our new channel with these settings. Per source 1 (Source 1) the blue channel of the background layer and its duplicate is taken as source 2 (Source 2) only the blue channel of the "Branches" layer is received, then they are blended using the Multiply mode (Multiply) between themselves. As a result of blending, a more contrasting image is obtained, which is the new alpha channel. (Alpha 1)... We are faced with the task of creating a sharp contrast of black and white colors in the image, otherwise, we will not be able to qualitatively cut the branch from the background and hide the background on the layer mask.

Step 5.

In the previous step, we increased the contrast of the image, but this is not enough for our purpose. Let's increase it even more. On the Alpha 1 channel layer (Alpha 1) go back to the Image-Calculations menu (Image\u003e Calculations)... This time we change the channel blending mode to Overlay (Overlay) and perform the rest of the options settings from the screenshot.

As a result of blending, we got another alpha channel “Alpha 2”, in which the light areas became lighter and the dark ones darker, which increased the contrast of the background and the object.

Step 6.

Even after two calculations, we cannot select the branch, because the sky has gray areas, and we only need black and white colors.

On the channel layer "Alpha 2" go to the menu Image-Adjustments-Levels (Image-Adjustment-Levels) or press the combination Ctrl + L. Now we will get rid of the gray background shade by making it completely white. In the Levels dialog box, move the white Highlights slider (Highlight) left to 167 until the background turns white.

Then move the black Shadows slider slightly to the right. (Shadows) up to 13 for a clear contrast between black and white.

Step 7.

Now we have done everything we wanted and are ready to select the branch and create a layer mask. Since we need to hide the background on the mask, not the branch, invert the colors in the image by pressing Ctrl + I on the keyboard. Now, load the branch selection by pressing Ctrl and clicking on the "Alpha 2" channel icon. A crawling stroke appears around the white branch, indicating that the selection is active.

Step 8.

With the Alpha 2 channel selected active, click on the RGB channel to restore the color to the image, and return to the Layers palette (Layers).

Step 9.

It remains only to hide the unnecessary background on the mask. To do this, go to the menu Layers-Layer Mask-Show Selection (Layer\u003e Layer Mask\u003e Reveal Selection) or click on the Layer Mask icon (circle in a square) at the bottom of the layers panel. Once you create a mask, your background will be hidden on it. In order to see the result of removing the background, turn off the visibility of the background layer by clicking on the eye of its thumbnail.

If you enlarge the image (Ctrl +), you will see how accurate the selection of branches is in this way.

Step 10.

The masking is done, and now we need to check the quality of the selection against a uniform background. Create a layer (Ctrl + Shift + N) above the background layer and fill (Edit-Fill or Shift + F5) any color to see the errors in the image.

Tint problem.

If you want to use this image on a different background or in a collage, then there is a problem with the presence of an unnecessary blue tint on the branches, which must be eliminated. To give you an idea of \u200b\u200bwhat this is about, I have chosen a different stock image for the background.

Removing unwanted tint in Photoshop.

There is an easy way to remove unwanted hue from a subject using the Hue / Saturation correction (Hue / Saturation) and decreasing the layer mask. If the shade is on the edges of the object, it will be enough to reduce the mask by 1 px and the problem is solved.

Since we already have a mask on the "Branches" layer, we cannot create another one. But there is a way out. We will later create a mask on the group's layer.
Select the "Branches" layer and place it in the group by pressing Ctrl + G on your keyboard.

Load the selection of the mask on the "Branches" layer (Ctrl + click on the mask icon), then go to Select-Modify-Shrink (Select\u003e Modify\u003e Contract), set the compression to 1 px. Next, create a mask on the layer with the group and for this go to the menu Layers-Layer Mask-Show Selection (Layer\u003e Layer Mask\u003e Reveal Selection)... In the Layers panel, you can see your new mask on the group layer.

If your image is low resolution, 1px compression can remove fine details from the subject. In this case, you need another way to remove the unwanted shade.

After we cut our mask, the blue tint is still present on the branches. Let's try to remove it using the Hue / Saturation correction (Hue / Saturation)by desaturating the blue and cyan tones or changing this shade to another.

Finally, take a look at the result before and after applying mask compression and creating an adjustment layer.

I hope you found something new for yourself in this lesson and now you will be successfully using this method of selecting complex objects.

For work we will use the image of an apple.

Step 2

Let's start with the basics. Can you access the Channels palette from the Window menu? Channels. It is in the Channels palette that we will do most of the work.

Step 3

In the Channels palette, we see four channels: RGB, Red, Green and Blue and look the same as the layers. But although the outer channels look the same as the layers, their functions are completely different. You may also notice that the channels reflect the current color mode of the document - in our case, this is the RGB color mode. Also, the Channels palette will change depending on the document's color mode. This is because each color mode uses a different color detection method.

Step 4

I think many of you are familiar with the basic concepts of how colors mix, but this is just one of the points of how channels work. Let's take a look at two basic color structures. First, our file is in RGB color mode, which is the color mode of a computer monitor, TV, and various portable appliances. The RGB color model uses the concept of additive color, which combines red, green and blue to create a full and rich color gamut.

Also, there is another color model - CMYK, which is intended for printing. Each of these two color models contains a set of color information - this information is reflected in the channels. Let's take a closer look at this. First, you need to open an image, and also open the Channels palette. If the image you opened is in RGB color mode, you will see four different channels in the Channels palette. In fact, in this color mode there are three channels: red, green and blue, and the fourth channel is a channel that is created automatically by the program and does not carry color information. Each of the three channels displays three different streams of color that make up the image you open.

Step 5

By default, in Photoshop's Channels palette, all channels are grayed out. Let's see how this can be changed. We will change the channel color to the red channel (Red).

Step 6

In the RGB channel, any white pixel will be at its maximum brightness. At this point, the red channel will emit the maximum amount of red light. Conversely, where black tints are present, the pixel will not emit light for that color. Since the apple is red, the pixels that make up this part of the image are actually lighter. And vice versa: if we convert the apple image to the CMYK color mode, then we will see something completely different. We now have five channels: cyan, magenta, yellow, black, and a channel that automatically combines all four channels.

In this case, the channels work differently, the way we work in a color space designed to simulate ink on paper. thus, you will see that where the pixel is white is the area of \u200b\u200bthe paper that nothing will be printed on. Well, where the pixel is black, this will be the area where the paper will be covered with this color as saturated as possible.

As an example, let's look at the magenta channel. You can combine magenta with yellow to set the color to red. So if we were to print an apple, a lot of magenta ink would be used. This is reflected in the magenta channel.

Note that areas of deep reds are saturated with blacks, while some areas that contain a small amount of reds are much whiter (reflection at the top of the apple). It turns out that channels are simply a way of splitting up different color information in a document, allowing you to customize and adjust the color.

I personally prefer to work with grayscale in channels. But if this is very difficult for you, there is another way in Photoshop to make it easier: go to the Edit menu? Preferences? Interface. In the dialog box that opens, check the box next to Show channels in color. After that, opening the Channels palette, you will see that the channel icons are colored in the appropriate colors: the red channel icon has become red, the blue channel - blue, etc.

In CMYK color mode, the magenta channel will look like this:

I'll turn off the Show channels in color feature for now.

Step 7

RGB and CMYK color models are the most common color models. Besides them, there are several more color models.

This color model differs significantly from the RGB and CMYK color models. This color model is not designed to mix color, ink or light. In fact, it is designed to emulate human perception of color. There are three main channels in the Lab color model. The first is the Lightness channel, which controls the relative brightness and darkness of a particular pixel. The other two channels (called a and b) contain up-to-date color information. This color model is used primarily for post-processing photographs and can be useful for establishing the correct color.

Multi-channel images contain 256 gray levels for each channel and can be useful for specialty printing. When converting images to multi-channel mode, the following information may be helpful. Layers are not supported here, and therefore flattened. The color channels in the original image become spot color channels. Converting a CMYK image to multichannel creates cyan, magenta, yellow, and black spot color channels. Removing a channel from an RGB, CMYK, or Lab image automatically converts that image to multi-channel mode by flattening the layers.

This color mode produces 8-bit images with a maximum of 256 colors. When converted to indexed color mode, Photoshop builds an image color table (CLUT) that stores and indexes the colors used in the image. If the color of the original image is not in this table, the program chooses the closest available color or dithers to simulate the missing color. This color mode allows you to reduce the file size of the image, while maintaining the image quality that is so necessary for multimedia presentations, web pages.

This mode uses different shades of gray. Each pixel in a grayscale image contains a luminance value that ranges from 0 (black) to 255 (white). This color mode can be useful if you intend to print in non-color, or it can be useful when separating objects from the background.

This color mode is the most basic of all existing color modes and consists entirely of black or white pixels. It doesn't even have shades of gray. This color mode uses only black and white channels and is not suitable for extracting objects from the background.

This is a completely different approach to working with color and this color mode is used mainly for adding interesting color tones to black and white photography (for example, sepia effect). Since this color mode has only one grayscale channel, it is also not suitable for separating objects from the background.

Command-Clicking Channels:

That's all I wanted to tell you about channels in this part of the tutorial. By the way, if you need to create a selection from a channel, do Ctrl + Click on the thumbnail of the channel you need to select. The selection will be created based on the black, white and gray pixels of this channel. Well, and about other ways of working with channels, read in the second part of this lesson.

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Translated from www.myinkblog.com, the author of the translation is indicated at the beginning of the lesson.

If you are just getting started with Photoshop and the Apply Image commands confuse you, then this tutorial is for you. In addition to the External Channel (Apply Image), this tutorial will help you understand how Channels work, as well as some applications of the Blend mode.

Final image
Here's the final image we'll be creating:

Joining External Channel (Apply Image)
There are several tools in Photoshop that are not recognized or understood. they are hidden or because the use of these tools is not immediately visible. But these tools provide useful options for various tasks. The Apply Image command is one that is not used very often, even for advanced users.

Before you start
I have provided links to the images, if you want you can use them. But my advice is to use your own images to get a clear understanding of the principles and their applications. But remember, this lesson is more of an exploration than a step-by-step lesson. So it is not necessary to focus on the process or steps just to achieve some specific effect, which can be achieved in other ways as well. But think about why we are using the External Channel (Apply Image)? How can the same principle be applied to other projects? What is the advantage? Let's start!

External Channel (Apply Image) at a glance
Externally, Apply Image is useful for overlaying images, for working with layer masks, and for editing an image. But if you dig deeper, you will find that the real strength of the Apply Image is in its overlay capabilities, enhancing and modifying the Channel information.
Below is a list of the different possible uses of the Apply Image:

• Composition - Blend or superimpose one image on top of another.

• Channel Information - Increase, replace and change individual channel information. Replace damaged channel information with normal information.

• Mask creation - By creating a mask from channels. Also create a quick base mask to select complex objects such as hair.

• Vivid Mask - Create a vivid complex mask from an image.

• Non-destructive editing - Using or borrowing information from another layer or file.

Now let's take a look at the benefits of using an External Channel (Apply Image):

• The file size does not grow as there are no new layers.

• The External Channel (Apply Image) offers two additional blend modes not available in the Layers panel - Add and Extract. In Photoshop CS5 Extract is also available in Blend Mode, but without the Scale and Offset options.

• Faster than copying channel information into layers and overlaying them.

• Overlay images that use different color modes, such as RGB with LAB or grayscale, which is not possible with other commands.

Never use an External Channel (Apply Image) directly with the base layer. Always duplicate the base layer and then apply an Outer Channel (Apply Image) to the newly created layer. The advantage is that later we can delete this layer and return to the original layer. Moreover, we can also apply a mask to the copied layer to control the effect.

Consider the Features of the External Channel
The External Channel command can blend two images together. Before getting started, you need to understand these important rules about this tool:

• Both images you want to blend together must be open and the same size.

• Blending Mode Add will lighten the resulting image. If the result is too light, you can set a negative offset value to darken the image.

• Blending mode Extract (Subtract) will darken the resulting image. It also has offset parameters, and you can lighten the result by setting a positive offset value.

• Blending images that use different color modes such as RGB with LAB or grayscale, which is not possible with another command.

Case 1: Changing Channel Data
You downloaded an image from a stock image site for your project. You liked the image, but the problem is that the photographer has exposed the photo too much. You have checked the channels and found that the red channel is too white. You don't have time to look for a new photo. You try different routines like levels or curves and play with blending modes. Although the image gets darker, details are not visible.
Another example is the channel palette, you notice that one channel is damaged. You think that if you replace the data of this channel with another good channel, the image will be normal. Another example, you are working with a small size or a low-resolution image without any choice. And you wonder if there is any process that can improve the image quality. So let's try the first sounding of the Outer Channel.

Step 1
Open the Female Replication image in Photoshop. Click on the channel palette and select individual channels. The red channel is almost white or too high. The green channel is slightly better than the red channel, although it also needs to be improved. The blue channel is better than the green channel based on contrast factor, but with slightly data loss. The damaged area looks mottled.

Step 2
Click on the Layers Panel and duplicate the main background layer. Rename it to “Red data”. Go back to the Channels palette and select the Red channel with the left mouse click.

Step 3
Then go to the Image menu, Image\u003e Apply Image and set the settings from the image below. Here we are mixing the green channel data with the red channel data in Multiply mode. Because the Multiply mode darkens the image, the resulting red channel becomes dark with good data from the green channel. The red channel now shows a good amount of contrast, which is a sign of a good channel.

Step 4
In the Layers panel, change the "Red data" layer mode to Luminosity. In Luminosity mode, the “Red data” layer will acquire the luminance (or contrast) data from the top layer, but neglect the color change data from the previous channel. As a result of our work, the details of the “Red data” layer have improved. Now duplicate the “Red data” layer and rename it “Green data”. Let's use an Outer Channel for the Green channel linked to the “Green data” layer to enhance the contrast details.

Step 5
Return to the Channels panel and select Green Channel. Then go to Image\u003e External Channel again and set the options shown below. Now we will mix the Green channel data with it itself in Multiply mode. The Contrast of the Green channel in Multiply mode looks much better. This process is also called Self-imposition.

Step 6
Go back to the Layers panel and select an image. Because we have duplicated the “Red data” layer and created the “Green data” layer without changing the Luminosity mode, the details of the “Red data” layer have improved.

Step 7
The resulting “Red data” layer looks a little darker. So change the opacity of the “Red data” and “Green data” layers to 20% and 60% respectively. The image now looks great. You can further control by adding separate masks to the “red data” and “green data” layers to hide the selected areas. Depending on how much information the final image takes from them, you can control the result.

In this tutorial, we will learn how to enhance the contrast and brightness of images in non-standard ways by applying blending modes to individual color channels. If you are familiar with Photoshop, then of course you know that we usually select Blending Modes in the Layers panel when we want to change the interaction or combination of a layer with the underlying layer / layers.

I'll show you how to apply blending modes not to an entire layer, but to individual RGB color channels (red, green, and blue channels) that Photoshop uses to create a full color image.

How do we apply blending modes to color channels? In reality, this is simple and easy thanks to the Apply Image command.
Working with color channels in Photoshop is a bit difficult topic for a novice user. I will touch on it superficially in this tutorial, but for those who are just starting to work with channels in Photoshop, I strongly recommend that you read the tutorial first. "ModelRGB and color channels " ... After reading the material, you will better understand what will happen when you further work with the External Channel dialog box in this lesson.

To learn more about Blend Modes, I recommend you read the tutorial on blending modes for an explanation of how basic blending modes work in Photoshop.

In this tutorial I will be working in Photoshop CS6, but later versions will work too. Here is the photo that I have currently opened in the program:

Original image

The first thing we need to do before moving on to further work with the image is to create a copy of it. If we look at the layers panel, we will notice that the original image is placed on the Background layer:

The layers panel shows that the image is placed on the background layer

Let's quickly make a copy of the background layer by pressing Ctrl + Alt + J / Command + Option + J on your keyboard. This action will not only create a copy of the layer, but also pre-open the new layer dialog box, in which we can name the layer before adding it to the panel. Name the layer “Apply Image”, then click OK to exit the dialog box:

New Layer Dialog Box

If we look at the Layers panel again, we can see that a copy of the image appears on a new Outer Channel layer above the background layer. It is always better to give the layers descriptive, "meaningful" names, which we did, otherwise you can easily get confused with the generic names that the program itself gives to the layers, such as "Layer 1" (Layer 1), which will not tell us anything about the purpose of the layer:

A copy of the image appeared on the "Outer Channel" layer

As I mentioned at the beginning of this tutorial, we usually select Blend Modes in the Layers panel because we tend to apply them to an entire layer. The blend mode selection button is located in the upper left corner of the layers panel. As an example, I'll quickly change the blend mode of the Outer Channel layer from Normal (the default) to Soft Light:

Change the Blending Mode to Soft Light

Changing the mode shows the interaction of two layers - the layer "Outer channel" and below the located background layer. The Soft Light mode belongs to the group of contrast enhancement modes, as it increases the contrast level of the entire image, which we see in our photograph. Color saturation has also increased slightly:

Image after changing the blend mode to Soft Light

I'll change the blend mode back to Normal to revert to the original settings:

Change the blend mode back to "Normal"

So, if changing blend modes in the Layers panel affects how layers interact as a whole, where does the work with individual color channels reflect and how do you use blend modes for channels? In order to answer the first part of the question, we need to take a closer look at the layers panel. We will see that it is located next to two other panels - Channels and Paths, each with its own icon. Click on the Channels panel icon:

Click on the channel bar icon

With this action, we will switch to the channels panel, where we can see the individual color channels: red (Red), green (Green) and blue (Blue), which make up our image. The RGB channel at the very top is not really a channel. It is the result of the merging of the red, green and blue channels, or, in other words, this is how we see a full color image (each color in the image consists of a combination of red, green and blue colors):

In the channel panel, we can find individual color channels

We can select an individual channel by simply clicking on it. I'll click on the red channel to select it:

Selecting the red channel

Selecting the red channel temporarily disables the green and blue channels and allows us to see only the red channel in the document window. Photoshop displays color channels as grayscale images, and each channel is an image with different shades of gray. This is what my red channel looks like in the document window. If you compare this version of the image with a full color image, you will notice that areas containing red in a color image are lighter in grayscale, while areas containing little or no red are look darker:

Grayscale image after selecting the red channel

Green channel selection

The document window now displays the green channel as a grayscale image. Note that it differs significantly from the red channel. Again, if you were to compare this image with the color version, you would notice that areas containing a lot of green appear lighter in grayscale, while areas with little or no green appear darker:

Grayscale image after selecting green channel

Finally, I'll click on the blue channel in the channel bar to select it, which will temporarily disable the red and green channels:

Blue channel selection

Now we have a blue channel in the document window, and again the halftone image is different from the red and green channels. This time, the more blue an area contains in a color image, the lighter it is in a grayscale image, and vice versa, the less blue there is in an area of \u200b\u200ba color image, the darker the area in a grayscale image. When you shortly select a single color channel in the External Channel command dialog box, keep in mind these three versions of color channels, represented by grayscale halftones:

Grayscale image after selecting the blue channel

To switch to the full color version of the image, click on the RGB channel at the very top of the channels panel. This action will bring all three color channels back to work:

RGB Mixed Channel Selection

And again we see a full color image:

The full color image reappears in the document window

External channel command

Now that we know that the color channels are located on a separate panel and each of them is a grayscale image, let's answer the second part of the question - how can you apply blending modes to them. You may have noticed that the Channels panel does not have a Blend Mode tab, unlike the Layers panel. In fact, we no longer need to work with the channels panel, so let's go back to the layers panel by clicking on its name (Layers):

Switching back to the layers panel

To apply blending modes to individual color channels, we use the External Channel command. To do this, select the menu line "Image" at the top of the screen, then from the list - "Apply Image":

Choose Image\u003e External Channel (Image\u003eApplyImage)

This action will open the External Channel command dialog box. If you have never worked with it before, then it may seem a little intimidating to you, but in fact everything is quite simple. In reality, we'll only use two parameters - Channel and Blending:

Channel and Overlay options in the External Channel command dialog box

The "Channel" parameter is responsible for selecting the channel that we want to use for work. By default, the RGB channel is selected, which, if you remember, is the blended channel located at the very top of the channels panel (the result of merging the red, green and blue channels to obtain a color image). The Blending parameter is responsible for choosing the blending mode we need. If we leave the Channel option with the RGB channel selected and just change the blend modes, we get the same result as when we selected a blend mode in the layers panel. For example, I'll choose the blend mode "Soft Light." In the dialog box of the "External channel" command (parameter "Channel" - RGB):

Leave the Channel parameter with the valueRGB and change the blend mode to "Soft Light"

You can clearly see that my image is no different from the one I got when I selected the blend mode "Soft Light" in the layers panel earlier in our tutorial. The same increase in contrast and color saturation occurred:

The Blend option of the Outer Channel command works the same as the blend modes in the Layers panel when a channel is selectedRGB

But things get more interesting when we choose any of three separate color channels instead of the RGB channel. I'll leave the blending mode "Soft Light" and change the "Channel" parameter from RGB to "Red". This way I will only overlay the red channel:

Selecting the red channel

This time the result is completely different from the previous ones. We can still see an overall increase in contrast due to the Soft Light blend mode, but the interaction of the red channel's grayscale image with the blend mode gives us a different effect. The girl's skin looks much lighter than before. The same thing happened with her hair, with a red top and areas of red, orange and yellow hues on the jacket. Essentially, anything that contains a lot of red in the image now looks lighter, while areas that contain little or no red, such as the blue and green areas of the jacket, appear darker than before:

The effect of the interaction of the red channel with the blend mode "Soft Light"

Let's see what happens if I change the Channel value to green (the blend mode is still Soft Light):

Switching from red channel to green

By selecting the green channel, we have another option for applying the effect. This time, areas with a lot of green are lighter, while areas with a lot of red or blue are darker. The most pronounced change occurred with the girl's skin, which became darker and more contrasting than when the red channel was selected:

How the green channel interacts with the Soft Light blend mode

Now I will change the value of the "Channel" parameter to blue:

Blue channel selection

In this case, we got the third version of the image, when areas with blue became lighter, and areas with red or green colors became darker. These variations of the effect would not have been possible (at least not without a lot of effort) if we had not been able to access individual color channels using the External Channel command:

Each color channel gives us a different way to apply the effect

Of course, we're not limited to just using the Soft Light blend mode when working with our color channels. We can choose any of the blending modes, as we would in the layers panel. I'll leave the Channel value at Blue and change the Overlay value to Overlay:

Selecting a blend mode "Overlay" for the blue channel

Like Soft Light, Overlay is a mode that enhances the contrast in an image, but to an even greater degree:

How the blue channel interacts with the Overlay blend mode

And here is how the Overlap mode will look when the channel is changed to Green:

How the green channel interacts with the Overlay blend mode

And this is what the red channel looks like in Overlap mode:

How the red channel interacts with the Overlay blend mode

The red channel image looks too saturated when interacting with the Overlay mode, but we can easily dim the colors if needed by lowering the overlay opacity. You'll find the Opacity option directly below the Blending option in the Outer Channel dialog box, and it works the same way as the Opacity option in the Layers panel. By default, the parameter value is 100%. I'll reduce its value to 60%:

Decrease the opacity to reduce the intensity of the blending effect

By lowering the opacity, we returned some of the highlights and shadows to the image:

Image after lowering the opacity of the Overlay blend mode

If you want to compare the processed and original images, just turn off the "Preview » (Preview) located on the right side of the dialog box. This will hide the application of the effect and allow you to see the original image in the document window. Select the Preview option again to return to working with the effect:

Toggle the "Preview" option on and off to compare the original and processed images

You will often find, especially when processing photographs of people, that the Soft Light and Overlay modes are the best for processing, but other useful blending modes are also worth trying, such as Screen and Multiply. ... Screen mode brightens everything in the image, while Multiply mode darkens. Try applying these modes to three color channels to see the result, then adjust the intensity of the effect by increasing or decreasing the opacity value. For example, in my case, I set the Channel to green, the blending mode to Multiply, and lowered the opacity to 40%:

"Channel" - Green, "Overlay" - "Multiply", "Opacity" - 40%

As a result, the image became darker and more detailed:

The Multiply blend mode is good for darkening an image. Try Screen mode to lighten it

When you're happy with the result, click OK to exit the External Channel command dialog box. You can then compare the processed image with the original again by clicking on the layer visibility icon (in the form of an eye), located to the left of the layer name "Outer Channel" in the layers panel. Click on the icon once to make the layer temporarily invisible and view the original image. Click on the icon again to make the Outer Channel layer visible:

Turn layer visibility on and off to compare the final result and the original image

And so we did it! We learned how to apply blending modes to individual color channels using Photoshop's "External Channel" command!

To look inside the channel, you need to open its palette in Photoshop. It looks and works the same as the layers palette and is in the same panel as the layers, but in a tab to the right (if you don't see it, choose the menu command Window \u003d\u003e Channels).

Similar to how layers work, when you click once to select a channel, Photoshop highlights it, showing you that it is selected. All operations performed from this moment will affect only him.

If you need to select several of them, click on each of them while holding down the Shift key. You can use this trick to, say, sharpen two at the same time. To enable or disable the display, click on the visibility icon to the left of the title (however, you cannot disable them all, at least one must be visible at all times).

There are several types:

1. Composite... Technically, this is not really a channel, it is provided for viewing convenience only. When you use a mode that contains multiple colors (such as RGB, CMYK and Lab), it shows everything at the same time, revealing the image in all its full color beauty.

Its name always depends on which mode you are working in. In mode RGBfor example it will be named RGB. But no matter what Photoshop calls it, composite is always at the top of the palette.

2. Color... As stated above, if you are working in RGB mode, then these are red, green and blue. In mode CMYK they are cyan, magenta, yellow and black. In Lab mode (we will consider in the following articles) these are Brightness, a and b. In all other picture modes you will find only one, named after the mode you are in.

3. Alpha channels... If you've ever saved a selection to use later, that's what you created. These are usually grayscale displays of saved selections, which are useful for highlighting a difficult area that you may need to use again.

4. Dies... They contain instructions for using special off-the-shelf paints such as Pantone colors. If, say, you're a designer designing an ad for a powerful new scooter in bright red, you can create a channel containing that color to make sure it prints correctly.

At the bottom of the palette are the following controls:

• Load content as selection... This button, which looks like a tiny dotted circle, selects all of the active content. This is useful if you are using information to highlight difficult areas. You can also load content as a selection by Ctrl-clicking the thumbnail.
• Save selection as channel... If you have an active selection, you can click this button to save the area as an alpha channel for future use. To assign a name, you can select the menu command Selection \u003d\u003e Save Selection or click the button while holding down the Alt key.
• Create new channel... This button looks like a small piece of paper with a folded corner. When pressed, Photoshop creates a new empty alpha channel. The program names the selection you create Alpha 1, Alpha 2, etc. If you want to enter a more memorable name, double-click on the name and replace it.
• Delete current channel... When you click on that tiny trash bin, it is removed. Once you've tweaked the duplicate to create a perfect selection or layer mask, you can discard it by clicking this button (or you can leave it dangling but out of sight by turning off its visibility icon).

Just like any other palette, this palette has a menu in the upper right corner (its button looks like a down arrow next to four small lines). This handy menu includes all the commands mentioned earlier, plus a few of its own:

• New. This command creates a new alpha channel in the same way as clicking on the above button at the bottom of the palette. The difference is that by choosing this menu command, you will open a dialog box in which you will need to assign a name and specify how the program should display the information.
• Create duplicate... If you want to create a copy to edit it, select this command. In this case, the program will display a dialog box in which you can assign a name and select its purpose (the same document or a new one). The assignment option is useful when you are creating a displacement map or using channels to create a high contrast black and white image.
• Delete... This command deletes the current channel or all if you have selected several of them using the Shift key. However, you need to save at least one, so if you select them all, Photoshop will darken this command.
• New spot channel... Useful for finished specialty ink called spot color. Read about it in the following articles.
• Combine with basic... Only typographic presses can recognize spot prints, so if you need to print a proof print on a regular desktop printer, you'll first have to use this command to merge.
• Options... This menu item is only available if an alpha channel is selected, and when creating or editing which, you can use the options to change the way selected or masked areas are displayed.
• Split... If you need to select each channel in the image into its own document, choose this command. Photoshop uses each one and copies it into a new document in grayscale. This method is useful for creating black and white images.
• To combine... This command combines a maximum of four open documents in Grayscale mode into a single RGB document (if you have three documents open) or CMYK (if you have four documents open). You can also combine the feeds of all open documents into a multi-channel document. This command can come in handy if you used the Split command to work on each of them separately, and now want to merge them into one document again.
• Panel options... The palette automatically displays thumbnails. If you want to disable this preview function or set a different thumbnail size, select this menu item. If you have a large enough monitor (17 ”or larger), use the largest thumbnail size possible.