In this tutorial we will learn how to enhance the contrast and brightness of images in non-standard ways, applying blend 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 blend modes not to an entire layer, but to the individual RGB color channels (red, green, and blue channels) that Photoshop uses to create a full color image.

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

To learn more about blending modes, I recommend that you read the tutorial about blending modes, which explains how the basic blending modes work in Photoshop.

In this tutorial I will be working in Photoshop CS6, but later versions will also work. Here's a photo of me in 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'll notice that the original image is placed on a layer background(Background):

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 the keyboard shortcut Ctrl+Alt+J / Command+Option+J. 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 again in the Layers panel, we can see that a copy of the image has appeared on a new Outer Channel layer located above the Background layer. It's always better to give your layers descriptive names, which is what we did, otherwise you can easily get confused with the generic names that the program itself gives to layers, such as "Layer 1", which will not tell us anything about the purpose of the layer:

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

As I mentioned at the beginning of the tutorial, we usually select blending modes in the Layers panel because we tend to apply them to an entire layer. The blend mode selection button is located on the left top corner Layers panel. As an example, I'll now 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 “Outer Channel” layer and the underlying 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 is what we see in our photo. Color saturation has also increased slightly:

Image after changing the blend mode to Soft Light

I'll change the Blending Mode back to Normal to return to the original settings:

Changing the blend mode back to Normal

So, if changing blend modes in the Layers panel affects how layers interact as a whole, where does working with individual color channels reflect and how do you use blend modes for channels? 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 of which has its own icon. Click on the Channels panel icon:

Click on the channel bar icon

This action will switch to the Channels panel, where we can see the individual color channels: Red, Green and 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, it is how we see completely color image(each color in the image is a combination of red, green and blue colors):

In the Channels panel we can find the individual color channels

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

Red channel selection

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 represents 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 to a full color image, you will notice that areas containing red in the color image are lighter in grayscale, while areas containing little or no red are lighter. look darker:

Halftone image after selecting the red channel

Green channel selection

The document window now displays the green channel as a grayscale image. Note that it is significantly different from the red channel. Again, if you were to compare this image to 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:

Halftone image after selecting the green channel

Finally, I'll click on the Blue channel in the Channels panel 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 grayscale image is different from the red and green channels. This time, the more blue the area in the color image contains, the lighter it is in the grayscale image, and conversely, the less blue the area in the color image contains, the darker the area in the grayscale image. When you soon select an individual color channel in the Outer Channel command dialog box, keep in mind these three versions of color channels, represented by grayscale images in different shades of gray:

Halftone image after selecting the blue channel

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

Mixed RGB channel selection

And again we see a full color image:

A full color image has reappeared in the document window

External Channel command

Now that we know that color channels are located in a separate panel and each of them represents a grayscale image, let's answer the second part of the question - how we can apply blend modes to them. You may have noticed that the Channels panel doesn't have a Blend Mode tab like the Layers panel does. In fact, we don't need to work with the Channels panel anymore, so let's go back to the Layers panel by clicking on its name (Layers):

Switch back to the layers panel

To apply blend modes to individual color channels, we use the Outer Channel command. To do this, select the menu bar “Image” at the top of the screen, then from the list - “External channel” (Apply Image):

Select “Image” > “External Channel” (Image >ApplyImage)

This action will open the External Channel command dialog box. If you've never worked with it before, it may seem a little intimidating, but it's actually quite simple. In reality, we will only use two parameters - Channel and Blending:

Channel and Overlay options in the Outer 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 blend channel located at the very top of the Channels panel (the result of merging the red, green and blue channels to create a color image). The “Overlay” parameter is responsible for selecting the blending mode we need. If we leave the Channel option with the RGB channel selected and just change the blend modes, we'll get the same result as choosing a blend mode in the Layers panel. For example, I'll select the Soft Light blending mode in the External Channel command dialog box (Channel option - RGB):

Leave the “Channel” parameter with the valueRGB and change the blending mode to “Soft Light”

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

The Outer Channel command's Blending option works the same as the blending modes in the Layers panel when a channel is selectedRGB

But things get interesting when, instead of the RGB channel, we select any of the three separate color channels. I'll leave the blend mode at Soft Light and change the Channel from RGB to Red. This way I'll only overlay the red channel:

Red channel selection

This time the result is completely different from the previous ones. We still see an overall increase in contrast due to the Soft Light blend mode working, but thanks to the interaction of the red channel's grayscale image with the blend mode, we get a different effect. The girl's skin looks much lighter than before. The same thing happened with her hair, with her red top and areas of red, orange and yellow on her jacket. Essentially, everything 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, look darker than before:

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

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 containing a lot of green became lighter, while areas with a lot of red or blue became darker. The most distinct change occurred with the girl’s skin, which became darker and more contrasting than when choosing the red channel:

Interaction of the green channel with the Soft Light blend mode

Now I'll change the Channel value to blue:

Blue channel selection

In this case, we received a third version of the image, when the areas with blue became lighter, and the areas with red or green flowers- darker. These variations of the effect would not be possible (according to at least without application great effort), if we had not gained access to working with individual color channels using the External Channel command:

Each color channel gives us its own option for applying the effect.

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

Selecting the Overlay blend mode for the blue channel

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

Interaction of the blue channel with the Overlay blending mode

And here’s what the “Overlap” mode will look like when you change the channel to “Green”:

Interaction of the green channel with the Overlay blend mode

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

Interaction of the red channel with the Overlay blend mode

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

Lower the opacity to reduce the intensity of the overlay effect

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

Image after reducing the opacity of the Overlay blend mode

If you want to compare the processed and original images, simply disable the option " Preview» (Preview) located on the right side of the dialog box. This action 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:

Turn on and off the Preview option to compare the original and processed images

You'll often find, especially when editing photos of people, that the Soft Light and Overlay modes work best, but other useful blend modes are also worth trying, such as Screen and Multiply. . Screen mode brightens everything in the image, while Multiply mode darkens everything. Try applying these modes to three color channels to see the results, 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, Blend 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 brighten it up

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

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

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

I recently read a translation of an article using channels in Photoshop on a “famous” site. The article emphasized that Photoshop does not distinguish colors, but sees all images in black and white gradation. Photoshop shows color images because we “expect” to see them in color, and it quietly adds some numbers that make the magic happen. It is not clear what the logic of such reflections is based on. Either because old versions of Photoshop showed the channels as black and white prints, or because of something else. It’s not surprising that questions in the comments in the style of “wow, so it turns out that from a black and white photo you can make a color one?”

For that matter, Photoshop doesn’t see anything at all. Photoshop is simply a program written by a person in a programming language. Photoshop does not see gray, white, red or green. Photoshop navigates graphics like Neo in the Matrix. He sees pixels as a collection of zeros and ones, and makes decisions based on digital parameters. Photoshop does nothing more than change digital values, the values ​​are converted into colors that the human eye can recognize. Other animals' eyes are structured differently, and they apparently need some other Photoshop, but it hasn't worked out yet.

It is also unclear where, finally, our domestic accessible and understandable articles about Photoshop, color, printing are, where our Dan Margulies are. The entire RuNet translates Western designers and graphics teachers. It seems that we have had design itself and good designers for a long time, and the only famous writer on the RuNet so far is Artemy Lebedev, and even then, he writes about something of his own. In this article I will try to address the issue of channels, going through the basics of the appearance of light and color along the way. We will go through the entire logic of the appearance of colors on the screen from beginning to end, and I assure you that by the end you will understand the essence of channels in Photoshop no worse than Dan Margulis. I'll start with the basics and tell you how color comes about in the first place. What is the difference between light and color. This is very important for a correct understanding of the channels. Moreover, I will try to highlight not only RGB channels, but also channels in CMYK and LAB.

Photoshop color space and channels

Let's agree right away: channels and color space are not the same thing. If we're talking about channels, then we're talking about channels. And not about RGB channels or CMYK channels. What is color space in Photoshop? Color space is the essence, the formula by which Photoshop assembles an image. The channels directly depend on the color space in which Photoshop works. If the color space is RGB, then these are 3 RGB channels, if the color space is CMYK, then these are other channels, channels for the CMYK color space. But there are many color spaces, and each has its own channels! It turns out the topic is bottomless? Margulis only scribbles ABC books one after another in the Lab space, but we just have an article. It's not that scary. Once you understand how the channels of one color space are arranged, you can easily understand the others. Therefore, we will start with RGB channels, but first let’s get started with the theory.

Color space in Photoshop switches to Image > Mode. If you go to this menu, you will see a series of color spaces in which Photoshop can work. This Bitmap, Grayscale, Duotone, Indexed Color, RGB, CMYK, Lab and Multichannel. Accordingly, each of these modes has its own channels, arranged in its own way. The channels themselves for any image can be viewed in the channels panel Windows > Channel. By opening this panel you will see the channels themselves and their final result. In some color spaces you will only find one channel. Others, such as CMYK, have four channels. If filters do not work for you, selection areas are not copied, some colors are not included, graphics are not imported from one window to another - urgently check the color mode. Most likely, the image does not have a typical color mode, such as CMYK or Indexed Color.

I'll say even more. If you opened black white image, it is very possible that its color mode is Grayscale, if opened GIF banner, saved from the Internet, its color mode is Indexed Color, since the GIF format is saved only in this mode. If you have a large TIFF file on hand, check the mode, most likely it is CMYK, since TIFFs are usually saved for printing in offset, and the color mode for printing in offset is CMYK. And only one color mode always wins. All filters work in it, colors are displayed, graphics are copied. This color mode is truly the king of modes, since Photoshop itself is designed to work with it. And the name of this mode is RGB. And most images, photographs and other graphics you'll work with will have this color mode. And that's why.

Monitors and RGB

RGB (Red- red, Green- green, Blue- blue) is the most common color model because any modern on-screen luminous devices are based on the RGB color model. Yes, Photoshop can simulate any color space, from CMYK to Lab, but ultimately what we see on the screen is converted to RGB in any case. We work in Photoshop, on the agenda is a printed TIFF file, CMYK color space, in the Chanel channels panel there are four paint channels. But when displaying the work area, the monitor converts them to RGB. Why?

This is how monitors are designed, and this is how almost all luminous screen devices are designed. And then you will understand why. Ultimately, it all comes down to the monitor’s ability to reproduce some colors in principle. In its hardware capabilities, in the quality of its matrix and color gamut coverage. Whatever color space we choose to work in Photoshop, the monitor displays it with using RGB. The monitor displays colors as best it can, as well and brightly as the quality of its matrix. So we all end up with our piece of hardware on the table in the end. You can work with excellent color profiles, in flexible color spaces with a wide color gamut, but all is useless if the monitor is bad.

Light and color

To reverse Locke's sayings, there is light and there is color. And light has color. This topic is not the subject of our article, but is necessary for a correct understanding of channels in Photoshop. And especially RGB and CMYK channels. What is light? Light is part of electromagnetic radiation. This is a natural phenomenon that ranks with other electromagnetic radiation such as infrared rays, x-rays, microwaves and ultraviolet radiation. All of them (electromagnetic radiation) are measured in nanometers (nm). Light is measured at 400-700 nm, and I think you can already guess why. Why in the radius from 400 to 700. Is it different? Exactly. And its difference is determined by its color.

Light rays of different colors are measured in different numbers of nanometers, with violet measuring 400 nm, green 550 nm, and red 700 nm. When refracted in a prism, light is split into its component colors: red, orange, green, blue, indigo and violet. Every schoolchild knows this from physics lessons. And based on all that has been said, we can draw simple conclusions that will help us understand the RGB channels:

• white “light” is the combination of all colors of the spectrum
• black “light” is the absence of light at all.
• gradually adding all the colors of the spectrum to each other “brightens” the light until it becomes white
• the gradual removal of parts of the spectrum “darkens” the light until there is no light left at all.

Surface color

The color of the surface is arranged differently, but is tied to light. We see the color of objects because objects reflect the light falling on them. Different surfaces have different reflective abilities. If a certain surface does not reflect light at all, but absorbs all the rays of the spectrum, then we see black. What else can you see if the object does not reflect light? If the surface reflects all the rays of the spectrum, we see white color. For example, paper reflects all the rays of the spectrum and we see it as white. The moon is white because it reflects the light of the sun, and not because it itself glows purely Samsung Led TV.

Further more. If, for example, a certain surface absorbs all the rays of the spectrum except blue, then this surface looks blue, since it reflects only the blue part of the spectrum. If an object reflects only one part of the spectrum, for example red, then we see it as red. If it reflects the devil and absorbs the devil, then we see the devil. For example, a surface may reflect a little yellow, a little blue, a little green, and absorb everything else. All other, “non-pure” colors consist of this confusion. They are formed by mixing reflected rays of the spectrum. Perhaps this is enough for the theory of color and light. Let's move on to the channels themselves in Photoshop.

Channels in Photoshop for RGB

From pure theory, let's move on to channels in Photoshop. When creating monitors smart people They didn't reinvent the wheel. The monitor emits light. The developers took advantage of what Mother Nature offered us and created RGB. How is it built? It consists of 3 channels: red (Red), green (Green) and blue (Blue). When superimposed on each other, 3 original colors create the composite colors magenta, cyan and yellow. Together, we get the usual rainbow or spectrum.

The three RGB channels act on each other in the same way that the rays of a spectrum act on each other. When superimposed on each other, a white color is achieved. If all channels are missing, it turns out black, which is logical. Either light or darkness. If one of the channels is missing, one of the composite colors (magenta, cyan or yellow) is obtained. Each RGB channel has a value scale from 0 to 255, where 0 is no light and 255 is the maximum possible light. In our case, this is not white light, but the light of one of the channels, blue, green or red. When all three channels are crossed, taking into account the fact that each channel can have a color gradation, from black to the lightest possible, the entire multi-million color palette in RGB is obtained.

I thought for a long time about how best to depict the overlay of color channels on top of each other, but in such a way as to take into account the gradation of each channel to black, that is, to the absence of light. After some unsuccessful experiments, I depicted them in the form of a flower. Although this flower does not show all possible shades of RGB colors, it does a good job of showing how RGB mixes channels.

RGB channels as a mask option in Photoshop

So what do we know about channels? Already quite a lot. We know that there are three channels in the RGB color space, blue, red and green. We know that when superimposed on each other, composite colors are formed and that each channel has a lightness and darkness parameter from 0 to 255. It's time to look at how an image is generated in RGB.

I open Photoshop, select a beautiful photo and turn on the channels. If you don't know where they are, open Windows > Channels. I will also use the panel Info And Color. They can also be found in the menu Windows. By turning on the channel panel, you will probably see the following picture: one color image, and 3 separate channels with black and white masks, which indicate the degree of illumination of each specific area of ​​​​the photo by a specific channel. If an area in the image is black, then this channel is completely absorbed by the surface; if it is light, it is completely reflected; if it is gray, it is partially absorbed and partially reflected.

You may also see a different picture, color channels instead of black and white. This means absolutely nothing, and does not at all indicate that Photoshop sees everything in color, black and white, or brown-crimson. Photoshop is just a program, it doesn't see anything. It sees the channel values ​​for each pixel and composes the image. Accordingly, the more colorful the photograph, the more it weighs, since there is a lot of information on the color of each pixel, and the more uniform it is, the more single-color pixels, the less the photograph weighs. Because the information on some pixels is repeated. Black and white photographs weigh significantly less than color ones, and White list, against a photograph of the same size, it weighs nothing at all.

Whether your channels in Photoshop are color or black and white depends solely on the version of Photoshop and the settings installed. If you see black and white channels, go to Edit > Preferences > Interface and check the box Show Chanels in Color. It doesn't make any difference. For color channels, the black area on a particular channel is the zero color intensity value, and the brightest (for example, red, on the red channel) is the maximum channel intensity value of 255. That's all. And also in black and white version. Black - 0 value, white - 255.

In this sense, each channel is a kind of mask, where the black area covers the image, the white area shows, and the gray area half-shows.

Let's consider the operation of channels with black and white images in RGB. For our experiments we will need palettes Color, Channels, Info And Color Picker. Open Color Picker and select clean grey colour. It is impossible not to notice that in a gray color without tint, the channel values ​​are equal to each other. Which is natural, because if R0 G0 B0 creates a black color (see, the absence of light reflection from the surface), and R255 G255 B255 creates a white color (see, a combination of the entire spectrum, a school prism), then it is logical that with a gradual increase in the values ​​of each channel with an equal value will result in a pure gray color without a hint of tint.

Let's do a little experiment. I opened the photo and using Image > Ajustiments > Desaturate converted it to black and white.

Now I have chosen the tool Color Sampler from the Tools panel and made 4 color proofs in different places photos. To display the numerical values ​​of the channels, I will open the Info panel. We see that in all 4 cases the channel values ​​are equal to each other. Let's complicate the task.

I'll go back to the color correction menu and apply the tint filter. Image > Adjustments > Photo Filter In the Filter panel, I'll select the solid blue color R0 G0 B255 and tone the photo slightly.

As you can see, the hue of the photo has changed, although it is still perceived as B&W. Let's look at our color swatches in the Info panel. The red and green channel values ​​remain unchanged. And the value of the blue channel exceeded the values ​​of the red and green. Due to this, the black and white photograph received its bluish tint, because the intensity of the blue channel exceeds the other two. I achieved clean results by using a pure blue R0 G0 B255 with zero values ​​for the red and green channels when color grading. If I had used a shade that was not entirely pure, for example R10 G15 B250, then my values ​​would not have been even. In this case, the filter would also affect the Red and Green channels, but the photo would still get its blue tint, since the value of the blue channel would be a hundred times higher than the others.

Channels in Photoshop and sepia

How is the Sepia effect created? The photo is still black and white. It just has a yellowish tint. How does RGB create the color yellow? Known as when superimposing Red on Green. That is, R255 G255 B0

Open a black and white photo Apply the effect Image > Adjustments > Photo Filter, but this time we will use the pure yellow color R255 G255 B0. It's not hard to guess what we'll get in the Info panel.

The values ​​of the Red and Green channels increased evenly, while the values ​​of the Blue channel remained unchanged. Due to this, the photo received a yellowish tint. Now that you understand the nature of RGB channels, let's look at a color image.

Channels in Photoshop and color image

With a black and white image everything is simple. In each area of ​​the image, all channels are equal to each other. The values ​​are of course different due to the degree of lightness and darkness, but all three channels are always synchronous with each other. With color images everything is different. Each pixel in a color image contains different information on all three channels. That's why it's colored. Due to this, a color image weighs more than a black and white image. Let's look at our photo.

The conditions are the same. Already a color photograph, the previous 4 color samples. 1) In the sky, 2) on the clouds, 3) on the dark part of the clouds and 4) on the tree. Let's see what's happening in the sky. In a section of the sky, the channel values ​​are 0 in the red channel, 56 in the green channel and 134 in the blue channel. The red channel is missing and we do not see it. 134 blue gives a pure dark blue color. And 56 of the green channel adds brightness towards the blue. As you remember, R0 G255 B255 give a bright blue color. The result is a blue sky, where the blue channel creates darkness blue tone, and green lightens towards blue.

The second value is the light part of the cloud. In the Info panel the values ​​are 240 for red, 243 for green and 247 for blue. The first thing that catches your eye is that the values ​​are extremely equal. This means the color will be close to grayscale. In our case, the values ​​are not only equal, but also high. From 240 to 247. Almost a maximum of 255, which indicates that the color will be almost white. And so it is. The clouds are extremely white. Now let's look at the shade. The values ​​are almost equal, but not completely. Blue channel 247 is higher than red, by 7 points. The green channel is also higher by 3 points. As you remember, 255 Green and 255 Blue give blue. This means the color will have a slightly bluish tint. And so it is.

In the third area, I selected the shadowed part of the cloud. First of all, we see that the values ​​are also high. 166 on red, 182 on green, 208 on blue. The values ​​indicate that this color is also quite light. But not as light as in the second sample. Light gray, and higher blue and green channel values ​​give light gray a distinct blue tint.

On the tree section, the values ​​are 3 for red, 23 for green, 16 for blue channels. The values ​​tend to zero, which indicates that the color is almost black. And so it is, the tree is really dark. As usual, the red channel is minimal; the green and blue channels win throughout the photo. Except, of course, grass, but more on that later. In this area, the green channel is significantly higher than the blue one, and accordingly the tree receives a dark greenish tone.

And a few more examples. I made two final marks on the light and dark parts of the grass. In this case, the blue channel plays. Its value is low. Red and green win. As you remember, the red and green channels give pure yellow. In our case, the red channel is not enough to switch the green channel to yellow, so the color goes towards the yellow-green swamp. But the green channel is not at its full maximum capabilities, if its value were inferior to the red one, the grass would have a reddish tint, but the green channel is stronger, and the grass is greenish. The blue channel also adds a slight tone, although it is almost imperceptible.

In our latest battle, the green channel is the clear winner. Its value is 137, half power, so the color is not bright but quite dark. The red channel tries to shift the hue towards orange, but to no avail. The blue channel is practically disabled.

And so each color section is added using RGB channels. The essence of the channel is a light intensity mask for each area of ​​the image. In the sky area, the red channel is black, which means the color consists of green and blue channels. There is no blue channel in the grass area. Green looks brighter than red, which means the grass will be mostly green. I hope you get the idea.

Reading channels by mask

This is what I want to achieve from you. I want you to understand that the channel image is a mask, where dark places mean the absence of the channel's action, and light places mean the effect of the channel's tone. Take our image as an example. You can understand the color of a photograph without seeing the colors. It can be read based on the channel masks. Now we will learn how to do this by deciphering the logic of color mixing in RGB.

The photo shows the sky, a tree, and a field. Let's see what the channels show. On the red channel the sky is completely black. This means that there is no effect of red in this area. The blue and green channels remain. On the blue channel, the color of the sky is clearly lighter, which means the action of the blue channel is higher here. But the green channel also makes its contribution. As you remember, the blue and green channels give blue. We get a light blue sky, darker towards the upper right corner, since the effect of green is noticeably weakened there.

Let's consider the field. The blue channel in this area is almost black. The brightest area is near the red channel, which is rivaled only by the green channel. Which means the field is yellow. Gradations on the green value move the color towards orange and dark red.

Let's look at the tree. On all masks its color is almost the same. This means the tree is quite colorless, close to gray. But still, on the red channel the tree is much lighter, and on the blue channel, it is darker. This indicates that the shade of the wood is red. In our case, the red is so strong that it reduced the gray to brown.

RGB and Screen mode

We can simulate RGB channel mixing ourselves. This is how I created most of the illustrations for this article. Draw ellipses on different layers, fill them with pure colors. Pure blue R0 G0 B255, pure green R0 G255 B0 and pure red R255 G0 B0. In the Windows Layers panel > Layers, change the layers' blending modes to Screen. The Screen blend mode cuts out dark pixels, favoring light pixels. But it also mixes different pixel tones in the same way it mixes their RGB color model.

I tried to write as concisely as possible, but the article turned out to be too lengthy. But now you fully understand how RGB channels are arranged in Photoshop, and not only in Photoshop. They are built the same everywhere, believe me. I will develop the topic of channels in my next articles on this topic. In the following parts I will describe the channels in CMYK and Lab, and also move on to their practical use in color correction and printing.

How to convert rgb to cmyk, Convert rgb to cmyk, Convert rgb to cmyk, How to convert rgb to cmyk in Photoshop, Convert color from rgb to cmyk, How to convert rgb to cmyk in Corel, Convert an image from rgb to cmyk, How to convert rgb to cmyk in coreldraw, How to convert rgb to cmyk in Illustrator, How to convert rgb to cmyk in illustrator, Photoshop cmyk, rgb conversion.

Using Channels in Photoshop

The article about channels is intended for beginners working in Photoshop.

Channels (the Channels palette in the program Adobe Photoshop are used to store service information: color and transparency levels. Using the information in the channels, you can evaluate the image quality, as well as apply various utility algorithms to eliminate defects. You can also save the shaded selection as a raster map and load it for work at any time.

Color channels

Channel— a halftone (grayscale) raster image used to store service information. Service information- this is color, transparency levels, service masks.

The contents of the channels are displayed in the Channels palette.

Photoshop renders a full-color image not as a single set of dots, but as three or four "channels" (grayscale) of pixels. The content of the channels depends on color model Images.

For example, an RGB image consists of red, green, and blue color channels, each of which is represented as a separate grayscale image. Similarly, the Lab image contains three channels, one of which corresponds to brightness, and the other two to chrominance. A CMYK image consists of four channels, each corresponding to a certain color dyes used in printing.

Channels correspond to the characteristics of a particular output or input device. For example, the channels of the CMYK model correspond to the different matrices with which the image is printed. The cyan matrix prints the image with cyan dye, the magenta matrix prints magenta, the yellow matrix prints yellow, and the black matrix prints black. Each RGB channel corresponds to a pass over the image of a scanning element of the corresponding color. The only mode that is not tied to any device is Lab mode. Its channels are pure abstraction.

Composite channel— standard mode, in which all color channels of the current color model are available for editing.

RGB image color channels

Let's create a new document with a size of 600x600 pixels, color model - RGB, background content - background color (black) - Ctrl+N.

Let's go to the "Channels" palette. We activate the Red channel when all channels are visible.

Select a brush with a diameter of 250, hard, white.

Click on the image.

You noticed that Adobe Photoshop associated white with the Red channel active as the maximum color content. Remember the RGB color model: a model of monitors, the maximum color is described by white, the absence of information is described by black.

Activate the Green channel when all channels are visible. Click the white brush in the image.

Activate the Blue channel when all channels are visible. Click the white brush in the image.

The result is an image where the maximum colors set with a white brush are the primary colors of the RGB model: red, green, blue. You also see that the intersection of these colors gives secondary colors, and the sum of all colors in the image (the intersection of the colors in the center) is white (remember that the maximum color with coordinates (255; 255; 255) is white).

CMYK image color channels

1. Open a photo of a parrot in the CMYK color space.

In the Channels palette you can see four color channels corresponding to the CMYK print and ink model.

2. In the CMYK model, everything is the other way around: 0 - maximum color, black content of the channel.

In the CMYK model, secondary colors are obtained by summing the primary colors according to the scheme: C + M = B (blue); C + Y = G(green); M + Y = R (red).

Customizing colors

The Color Settings dialog box allows very important parameters about how exactly Photoshop displays colors and converts them. A clear understanding and selection of the correct parameters is the key to successfully working with color in Photoshop and ensuring correct color reproduction in your images. This dialog box is one of the most important windows in the program. The settings you specify affect how images are opened, how pixels are inserted from one image to another, how colors are displayed on the screen, and how the user is notified when colors change as a result of a particular operation. Therefore, you should definitely understand the purpose of the various options available in the Color Settings dialog box.

How Photoshop works with color

Before we dive into the details of the Color Settings dialog box options, let's look at some more general issues. It would be wrong to simply tell which checkboxes to check or which radio buttons to select; After all, you need to have knowledge of the conceptual capabilities of the Color Settings dialog box and color management in Photoshop. At the most basic level, a digital image is nothing more than a collection of numbers. The image contains a grid of pixels, as well as information about the color of each pixel (or tint, in the case of a grayscale image), represented as a numeric code. In the case of RGB images, each pixel has three values, one each for red, green, and blue. Of course, working with an image in Photoshop is much nicer than working with a bunch of numbers, but when you edit images, you are actually changing the characteristics of the pixels. The numbers assigned to pixels tell Photoshop exactly how each pixel should appear on the monitor screen; numeric values are also used when printing images. The problem with this approach is some ambiguity. When using watercolors, oils, colored pencils or crayons, the images look different. When digital images specific shades depend on whether the image is displayed on a monitor screen, printed on an inkjet or photo printer; however, everything also depends on the specific devices. To standardize the display and printing of colors, Photoshop's color management system is based on four key principles.

1. Control your work environment thanks to stable lighting conditions and neutral wall colours.

2. Have a properly calibrated monitor with the correct profile that tells Photoshop how to display color.

3. Use of an RGB workspace that is independent of specific devices; this means that the interpretation of the shades determined by the given numbers does not depend on a specific device such as a monitor, scanner or camera.

4. Adding ICC (color descriptors) profiles, which tell Photoshop and other ICC-compatible applications how to display colors in an image.

The importance of monitor calibration and color proofing

The importance of controlling your viewing environment and having a calibrated monitor with the correct profile cannot be overstated. Just imagine the following situation: your monitor is not calibrated and its profile is inaccurate. In this case, there is no need to talk about color accuracy. If you have never created a profile for your monitor (at a minimum, you can do this by using the calibration utility that came with your operating system), I recommend that you avoid performing complex printing tasks until the appropriate steps are completed.

Workspaces

The workspace determines how Photoshop interprets numeric color codes and also ensures visual consistency of shades. The workspace affects all new images you create in Photoshop, as well as images that have not been set to a color profile (which is often the case with images taken with a digital camera). Because the workspaces available in Photoshop do not represent colors as they are defined specific device such as a monitor or printer, displaying correct shades on the screen of a calibrated monitor is only possible when using the exact monitor profile, as well as when saving a color profile along with the image (details).

Color profiles

If you put five people in one room and ask them to close their eyes and imagine the color purple, it is unlikely that they will all imagine the same shade. In addition to obvious differences in brightness, such as light magenta and dark magenta, there may also be differences in hue and saturation. Are we talking about a dark purple shade with a blue tint, or about purple with a hint of lilac? Without being able to accurately determine the color, many definitions of purple can be obtained. To obtain a more accurate description of the shades, it is necessary to add some additional information. In the case of digital images, the ICC profile acts as a source of additional information, which allows us to talk about the correct interpretation of colors in the image. A color profile is a description of exactly how different shades should be displayed on screen or printed. In addition to the monitor profile and device-neutral workspace, the color profile is the third critical component in ensuring that the tones of an image are handled correctly in Photoshop. Any file you work on in Photoshop must be saved with the embedded color profile (the corresponding option is available in the Save As dialog box). Having a profile tells Photoshop and other ICC-compatible applications exactly how the shades should look. I don't even know how to emphasize the importance of matching the color profile to the image. Color management experts Bruce Fraser and Andrew Rodney believe that without an embedded profile, the file is simply an RGB "mystery object." Photoshop has no idea how to display different shades, so when displaying them it is guided by the parameters of the current workspace, which cannot always be set correctly.

ADJUSTING COLOR IN PHOTOSHOP

Adjusting colors in Photoshop is often overlooked by self-taught users when mastering the program. People can usually get by without any knowledge about it. Is it really worth knowing about adjusting colors in Photoshop?

The answer to this question depends on how seriously you intend to work in Photoshop. If you want to become a professional, then any additional knowledge will give you an advantage when working in the program. Basic knowledge can make your work in Photoshop much easier.

Therefore, in this tutorial I will give the basics that you need to know about adjusting colors in Photoshop.

In order to set up the color management system in Photoshop, you need to run the command Edit - Color Settings (Ctrl + Shift + K).

By default, the window that opens will have the following settings:

Let's look at all the settings in more detail.

WORKING SPACES

RGB

RGB colors are created by adding to black, which is why this color model is called additive. It is very suitable for display on a monitor screen.

You will most likely have the SRGB IEC color profile installed by default. It is good for most simple Photoshop tasks, but does not provide a rich color palette.

For web designers and photographers, it is better to use the Adobe RGB profile (1998). It offers a wider color range.

The difference between them is still not so significant, it’s just that the SRGB profile was created for less expensive displays.

Nowadays, more and more photographers are choosing to use the ProPhoto RGB profile.

It has a much larger range of colors, some of which are actually beyond human vision. However, it has its downsides. One of them is that when converting color gamut, using this profile may end up producing undesirable results. Therefore, before you start working with this color profile, you should gain some additional knowledge about working with it.
Also, do not confuse sRGB IEC with Monitor RGB - sRGB IEC (Monitor sRGB IEC). If you choose the second option, you may get different results on different displays.

CMYK

The CMYK color model is based on the fact that the sheet of paper itself is white, i.e. reflects almost the entire spectrum of RGB, and the paints applied to it act as filters, each of which “steals” its own color (red, green or blue).

CMYK colors are determined by subtracting one of three RGB colors from white.

The CMYK system was created and used for typographic printing. Before sending to print, make sure your image looks correct in the CMYK color profile.

The default here is U.S. Web Coated (SWOP) v2.

You can select the “Load CMYK” option and load the one you need.

GRAY/SPOT

Leave the Dot Gain at 20%.

COLOR MANAGEMENT STRATEGIES

There are three settings you can configure here. Let's look at them in more detail.

OFF

If you select this option, the embedded color profile (or lack thereof) will be ignored and the image will be saved without a color space description.

SAVE BUILT-IN PROFILES (PRESERVE EMBEDDED PROFILES)

This option will allow you to take into account the embedded color profiles and use them when processing images. Newly opened images are in the color space described by the color profile embedded in the file.

CONVERT TO WORKING RGB (СMYK/GRAY)

If the embedded color profile in Photoshop does not match the working color space, the program converts the image from its color space to the working one, assigning it a color profile corresponding to the working color space.

Informer code Informer_2015/07/09 14:38:07 Copy the piece of code below to your website in the prepared place for the informer. Attention! If you have already installed the widget on your site, you cannot change the loader code. Compact code Asynchronous code

Click on the “More options” button on the right, under the “Ok” button, to expand the color settings panel completely.

After clicking this button, new fields will appear.

CONVERSION OPTIONS

MODULE (ENGINE)

Designed to select a color management system to apply color transformations. It is preferable to choose the Adobe (ACE) option, which corresponds to the color management system built into Photoshop.

METHOD (INTENT)

This setting determines the method used to convert color between spaces. The most commonly used methods are Relative Colorimetric and Perceptual.

Relative colorimetric(Relative Colorimetric) - when selecting this option, all drop-down color range output device, the colors are cut off and the closest ones are substituted. All other colors remain unchanged.

Perceptual(Perceptual) - in this case, the visual relationships between colors are preserved. Absolutely all colors received from the input device are converted to their equivalents within the color range of the output device.

Use black point compensation(Use Black Point Compensation)

When you select the Use Black Point Compensation check box, the darkest of all neutral colors in the source color space is converted to the same color in the target space. This is very important for maintaining black color during various transformations.

COLOR PROOF OPTIONS (PROOF SETUP)

Allows you to set proof print settings.

Located in the View menu - Proof options (View - Proof Setup).

With this function, you can see a preview of the image on the screen in accordance with the set color profile of the output devices that are available in the operating system.

The screen version will give a fairly accurate idea of ​​how the image will look after printing.

To quickly turn it on and off, use CTRL combination+ Y (or go to the View menu - Proof).

If your colors look strange, check that you haven't accidentally turned this feature off. If you see a backslash with a color profile at the end of the file name, then you have found the reason.

In the "Proofing Options" section there are various settings.

CMYK shapes (Working CMYK) allows you to create a proof based on the CMYK workspace as defined in the Color Settings dialog box.

Mac/Win RGB
commands let you estimate how an image will look on a Mac and Windows monitors. Can be quite useful when you are developing a cross-platform project.

Custom- When you select this option, the following dialog box will appear:

Using these options, you can customize the soft proofing mode for any device.

Simulate paper color(Simulate Paper Color) - When you select this option, Photoshop will try to display on the display the color of the paper on which the print will be made. The quality of such a prediction strongly depends on the quality of the profile, since this is the only source of information from which Photoshop can get information about the parameters of the paper.

Simulate black paint(Simulate Black Ink) - performs a similar function, only Photoshop tries to display on the screen the darkest possible color that can be obtained on the target device.

MANAGING COLOR PROFILES

CHECKING THE COLOR PROFILE INFORMATION OF A FILE

So, we learned how to adjust color in Photoshop.

Now let's see where to find out information about which color profile is embedded in the file currently open.

Open any image.

In the lower left corner of the main Photoshop window we find a small panel for displaying various information.

Click on the right arrow, select Document Profile in the menu that appears, and information about the ICC profile will appear on the screen:

ASSIGNING/CONVERTING COLOR PROFILES

Used to assign or transform a file's color profile.

Performed by the command Edit - Assign profile (Convert to profile) Edit - Assign Profile / Convert to Profile.

Here's the most important thing. Now you have basic knowledge about how to adjust colors in Photoshop, as well as what color profiles are and how to apply them when working.

Layers are currently the most powerful tool for working with photographic images. When you edit a photo, whether in Photoshop or Paint Shop Pro, you can't do without multiple layers of the image. Sometimes more complex layers are used - custom layers, effects and masks based on layers. Layers are everywhere. And the question involuntarily arises: how did users manage without them before?

The answer is simple - using channels. You can easily spot a Photoshop veteran by the fact that he uses the Channels palette as often as the Layers palette. But this should not be regarded as old-fashioned. Rather, this is evidence of professionalism, since the use of channels opens up wide opportunities.

So, what is a "channel". The standard definition - "a two-dimensional array of information, usually 8-bit" - is unlikely to clarify the situation. Therefore, let's take a closer look at the two main types of channels - color information and alpha channel - from the point of view of their practical application.

Color channels

The easiest way to see color channels in action is to use Photoshop's Channels panel. Open a regular 24-bit RGB photographic image. In the channel palette you will see 4 layers, each with its own icon: RGB, Red, Green and Blue. If you click on RGB, you will see the image that you usually see - composite and full color. For each of the other channels, a grayscale version of it is displayed. The keyboard shortcuts Ctrl+1, 2, 3 allow you to view each of the color channels separately, and Ctrl+~ - a regular composite image.

The full spectrum of RGB colors is created from the red, green, and blue color channels, where they are represented in a gray scale.

To understand what information is displayed in the Layers palette, it is worth observing the channels when working with a test image of a rainbow gradient (in other words, an image of all the colors of the rainbow). In a grayscale image that represents a channel, each of the pixels can represent one of 256 values. You will see that the red part of the rainbow when viewed in the red channel will be white. The yellow stripe of the rainbow will be white in the red and green channels, but will be black, i.e. absent, in blue. Actually, the image of a rainbow shows that a full range of of 16 million colors can be obtained by combining values ​​from 0 to 255 for red, green and cyan (256 x 256 x 256). In our image, the yellow stripe corresponds to large values ​​of the red and green channels and 0 to the blue channel. Photoshop works with an image not by individual pixels, but by channels. In this case, three eight-bit layers - red, green, blue - are superimposed, and we get the final image.

Of course, not all images are created in RGB, but this is not a problem since the channels are very easy to customize for different needs. We can convert our image to a different mode using the Image > Mode command. For Bitmap and Grayscale there is only one channel, which represents 256 values ​​from black to white. In Lab mode there are three channels: A (color value between green and red), B (between blue and yellow) and L (luminance value). Separating color from its brightness can be very useful. Select the luminance channel and convert it to a grayscale image. The result will be much better than if you converted the scanned RGB image.

The Lab color model can be very useful. But still the most important, after RGB, is CMYK. This model is print oriented. Convert the rainbow image to CMYK. The first thing that catches your eye is the sudden change in some colors. The fact is that CMYK does not support many pure RGB colors. The second difference is that four color channels have appeared: Cyan, Magenta, Yellow, Black (turquoise, purple, yellow, black). Look at the yellow stripe of the rainbow in the yellow channel - you will see that it is represented by black.

In the CMYK palette, the channels represent the ink colors used in multi-layer, four-color printing.

This mode differs significantly from RGB because Photoshop has to work with ink colors that combine with each other in a subtractive manner (summing all the colors together results in black). In RGB, on the contrary, the principle of addition is applied, and the superposition of all colors will give white. But, by and large, all color models are similar to each other. And Photoshop can recreate the full gamut of any of them with no more than four eight-bit channels, each of which has no more than 256 values ​​(or 65,536 values ​​if you really want to and go to Image > Mode and choose a 16-bit channel).

Channels are the primary tool for working with color, so it's worth looking at the Channels panel occasionally to learn how Photoshop creates different colors. This is especially true when working with a CMYK model that is designed for printing. When working with RGB, what you see on the monitor does not always correspond to what will come out when printed. Although the values ​​of each channel reflect this. Moreover, if you want to replicate an image, you need to consider factors such as dot blurring and gray component replacement. This means that accuracy in working with color channels is very important, since color separation subsequently depends on it.

Channels are useful for more than just CMYK printing. You will find their use in RGB as well. Let's say you can edit not the entire image, but a separate channel. When adjusting color, it is worth looking at individual channels to identify defects in the scanned image. For example, if you find a blurred or misaligned area in the red channel, you can correct this issue by using a sharpening filter or adjusting the levels.

And in order to create some special effect, you can apply an artistic filter to one of the channels. In any case, you can immediately see the result of your actions on the composite image - just make the RGB channel visible. Just remember to select the desired color channel again later if you continue to work on it.

The channel merging function provides ample opportunities. For example, using the Apply Image command, you can overlay information from any channel of another image of the same dimensions onto the RGB channel of our image and adjust this effect, changing the opacity and color blending mode. The Calculation command allows you to select two layers and create new layer, selection or document. If you use the subtractive color mixing mode, you will select areas of the image that have changed compared to the original.

With the introduction of the Channel Mixer command and custom layers in Photoshop 5, the ability to combine channels has expanded. The channel mixer function is only used for individual images and allows you to customize each channel by adding information from other channels. With its help, you can create special effects, swap channels, and correct color defects in scanned images. It's also ideal for creating "tinted" and high-quality halftone images (and you can control how each color channel is converted to grayscale).

Channel blending is very helpful when converting color images to grayscale.

Adjusting colors using channels will undoubtedly come in handy. But the most common way to use them is to work with secretions. Often, image elements are much clearer in a single channel than in a composite image. For example, selecting a bear in the bear.psd training file is much easier in the blue channel.

Alpha channels

Once you've created a selection, you'll probably want to save it. This can be done in the alpha channel. To do this, use the “Selection > Save Selection” command or the “Save Selection as Channel” icon in the Channels panel. After this, a new channel appears in which the selected pixels are displayed in white, the unselected ones in black, and the blurred pixels at the border of the selection in shades of gray.

By double-clicking on the channel icon, you can rename it and set the color it will appear in the composite image. You can work with the alpha channel like any other, for example, adjust levels or apply filters. Moreover, you can edit this channel using a brush - for example, paint over defects. When you are satisfied with the result, use it. To do this, convert the alpha channel into a selection using the Selection>Load Selection command, the Load Channel as Selection icon in the Channels panel, or simply by Ctrl-clicking on the channel icon. If you have multiple alpha channels, you can create more complex selections. For example, you have selected and converted an image of a person and bushes in the background to alpha channels. You can select only the bushes if you select them and load the channel as a selection using the "subtract" option. Keyboard shortcuts will speed up this procedure: click on the icon while holding Shift+Ctrl - this will add new area to the selection, Alt+Ctrl+click - will subtract from the selection, Alt+Shift+Ctrl+click - will give the intersection of two selections.

Alpha channels can be saved and loaded as selections.

Once you've converted the alpha channel to a selection, it will immediately appear on screen and you can transform it, copy it to a new layer, or edit it in any way. The flickering dotted line along the edge of the selection does not very accurately indicate its boundaries - you need to take this into account. It only displays alpha channel pixels that have gray intensity below 50%. For most selections this makes little practical difference. But the advantage of the alpha channel is that it allows you to work with 256 levels and thus create complex, variable transparency masks.

How can you use these masks? Here are some examples (it's actually easier to do than it looks when you read it). Click on the "Create New Channel" icon and create an empty alpha channel, then apply a gradient to it and select the composite channel again. Ctrl-click on the alpha channel icon. Now apply any artistic filter to the created selection. Its effect will depend on the halftone values ​​of the gradient mask. It will seem that the photograph is gradually turning, for example, into a painting.

The alpha channel can be used as a variable opacity mask.

Another example: create a copy of the alpha channel from a text selection and apply a Gaussian blur to it. After that, subtract the original channel (Alt+Ctrl+click) and you will get a new channel that will show only the noise surrounding the text. Now select this area in the composite or any of the color channels. You can adjust the levels so that the selection glows, or even remove the original text and the glow appears to be part of the photo.

You have the foundation, now experiment - you can create many effects using shadows, extrusions, vignettes, etc. Surely, if you get serious about this, you will need the ability to save alpha channels with your file. But Photoshop features in this regard, they are surprisingly small - the program supports saving the alpha channel in a tiff file or in Photoshop itself (but the number of channels in a file, including color ones, is limited to 24). This won't pose a problem if you only work in Photoshop. But the presence of an alpha channel can significantly affect the export of a file to one of the standard formats. For example, when saving for the Web, in the dialog box that appears, you can use the alpha channel as a mask to adjust the quality and, accordingly, the size of jpg and gif files. Using the alpha channel, you can draw attention to a certain part of the image that will be of the highest quality. The quality of other areas of the image will deteriorate, but this will significantly reduce the overall file size. Alpha channels are also useful when working with transparency. Create an alpha channel that covers the area that you don't want to be visible in the web version, and Ctrl-click to select that area. Now call the Transparent Image Export Wizard and select gif. The selected area will become transparent in the final file, and you will be able to avoid making irreversible changes to the original. The wizard allows you to export the image to a png file that supports 24-bit color and 8-bit transparency. If you create an alpha channel with a radial gradient, you will get a vignette. Unfortunately, few programs support 32-bit png files with transparency. The only exception is, perhaps, Director 8.5.

With the ability to add spot colors in CMYK, alpha channels are also useful for high-quality printing. Select the area of ​​the image that you want to print as a color fill, and then use the New Spot color command from the Channels panel menu. When you set a color, click "Custom" and select a color, for example from the Pantone library.

Please note that adding a color fill is not as simple as it seems. The image on the screen, as you know, does not always correspond to what is printed. Ink colors often cannot be represented in RGB and Photoshop simply shows what it thinks the image should look like when printed layer-by-layer. If you save your file in DCS 2.0 format and load the EPS composite image into a professional publishing program, you can color separate the four primary colors and custom color files you created.

The custom color channel allows you to display ink colors that are not included in the CMYK palette.

There's no doubt that channels play a very important role in photo editing, from adjusting colors and highlights to working with images for the web and high-quality prints. But time moves on, and layers often produce better results than channels. Having created a selection, copy it to a separate layer - and you can work with it independently, and, if necessary, return to the original version. The same goes for many other effects that were previously created using channels. Today, custom layers, effects, and layer-based masks do a better job of accomplishing this task.

The canal system was also improved. So, although in many areas channels are gradually being forced out of use, they are unlikely to disappear completely. If only for the simple reason that layers are created based on channels. Strictly speaking, a layer is a set of independent color information channels and alpha channels, one of which controls transparency, and the second acts as a layer mask. The same goes for custom layers, which are essentially alpha channels through which color is adjusted.

Photoshop, like any other photo editor, creates an image on the screen by processing values ​​from the color and transparency channels of the layer. And so, one by one, all the layers from the background to the foreground. Of course, in reality, working with an image is much more complicated - the program calculates color mixing modes, opacity, settings, etc. But it's based on a step-by-step mathematical process. The program does not see the image; it works with the data array of each channel. Any photo editor “thinks” in terms of channel categories. This is a habit worth adopting as a professional user.

In this article we will talk about CMYK channels in Photoshop. What are they for and how to work with them? How are they different from RGB channels? In the last article, we found out that RGB channels reflect the work of the RGB color model in Photoshop. Channels for CMYK perform the same task, but in a different color space. You will learn about what this space is, how to effectively work with CMYK channels and do color correction for printing in this article.

In my opinion, I managed to create the most understandable and simple article that clearly demonstrates the principles of working with CMYK channels and the basics of CMYK color correction.

• Part 1:

CMYK color model

A lot has been said about the CMYK color model even on Chronofag.ru. Therefore, I hope that everyone is familiar with the theory of the CMYK color model. This article is more practical plan. Unlike RGB, CMYK displays colors on the screen in a form in which they can be printed in a printing house. Working in CMYK is an essential attribute of a print designer. Therefore, it is especially important for every beginning designer to understand the principles of his work.

The CMYK color space is based on the principles of mixing inks during printing. While RGB channels subtract color information, CMYK channels add color information. With the maximum value of the RGB channels (R 255 G 255 B 255), we get white color (prism effect). In CMYK it's the other way around more information the darker the paint on the channel. In RGB - zero values ​​- black. Which is logical, there is no information about light, which means there is no light. In CMYK, on ​​the contrary, there are zero channel values ​​(C 0 M 0 Y0 K 0), which means the color is white, since there is no paint.

The principles of nature lie in both color models. Principles of radiation RGB lights and principles of CMYK light absorption. One problem. Modern printing has failed to display exclusively (in cyan, magenta and yellow). And even if it were possible, spending three layers of 100% paint to extract color is not rational and expensive, given that most of the printing is black text. Therefore, in CMYK there is an additional fourth channel K (black). However, you can read more about the features of the CMYK color model separately.

Principles of interaction of CMYK channels

Only practice is better than theory. You'll find the Channels panel in Windows > Channel. can be done via Image > Mode > CMYK (Image > Mode > CMYK)

It is very simple to understand how an image is constructed in CMYK channels. After all, each of us painted with paints in childhood, mixing different shades with each other. And most of us certainly know that mixing red pigment with yellow produces orange. When blue and yellow are mixed, green comes out. This is why it is so easy to understand the principles of CMYK, because everyone has experience in painting with paints.

CMYK channels work exactly the same. Only if in the gouache palette we had 10 or more paint pigments, in CMYK there are only four. Cyan, Magenta, Yellow and optional black. Black ink should ideally be used only in areas where three CMY inks are not powerful enough to produce a rich black. Therefore, the black channel in CMYK is contrasting.

Moreover, you can easily simulate CMYK channels by creating your own own image using masks. In this article we will do such a trick. But first, let's take a simpler example.

Let's take for example a pure yellow channel and a gradient, where on one side we have Y100, and on the other side Y0. On other channels the values ​​are zero.

Add the same purple gradient to it and blend it together. It is logical to assume that on different segments of the gradients we get combinations of different shades of paint. On the gradient we have M100Y100 - red, in the middle M50Y50 - a less saturated red. The less paint, the less saturated the color.

Let's add a blue gradient at the bottom. What happens when you mix cyan and magenta? Dark blue. And different shades of saturation.

Now let's move the blue gradient to the center and get a combination of all three channels, where point 1 is the darkest shade that can be obtained by combining three colors together.

So far our gradients have been in a row. And the saturation of colors changed in proportion to each other. Now let's unfold them and put them on top of each other completely random order. I chose Oval as a more convenient shape.

Several things are clear from this picture:

1. The fewer channels, the purer and clearer the color.
2. The more strange compounds there are in the percentage of paints, the more unattractive the color.

Everything is based on these two simple rules. The more paint, the darker the color, the more confused digital values, the duller the shade and the greyer/blacker the printed graphics. Let's select several points in our image and take a color proof from them using the Eyedropper Tool.

In sample 1, 2 and 3 we have two channels and pure colors. In sample 4 there is no obvious gain in any channel and the color is dirty.

Mixing paint is the basis of working in CMYK. Novice designers are accustomed to perceiving paint as a color on a monitor. They find it difficult to visualize digital CMYK values ​​as if they were real ink on paper. They choose a color from the Color Picker panel and don't look at the numbers. The result of such work is the same. Pale print, gray colors.

Mixing paint on gradients

Gradients pose particular challenges. It is not always clear to a novice designer by what logic CMYK paints are mixed. When I started working in Corel Draw, the results of gradients shocked me. I chose a gradient from red to black and got amazing results. Red on one side, black on the other, and muddy in the middle.

But if you understand what happens on CMYK channels, it is much easier to understand this problem. After all, if you know that the red color is a mixture of the Magenta and yellow channels, and the black paint is on a completely different channel, then the problem of the gray transition is obvious. Here's what's happening on the channel.

The loss of red paint from the middle is the source of the problem. If we take a color proof from the center of the gradient, we will get the values ​​C0M50Y50K50. What does a color look like with these values? This is exactly what it looks like.

But if we had drawn the same gradient on paper, there would have been no problems. After all, on an intuitive level, everyone understands what colors need to be mixed to get a gradient from red to black. You need to take red and black paints and mix them together, reducing the pigment of the black paint. Red paint should be present 100% in each section of the gradient.

In our case, the red paint decreases in proportion to the arrival of the black paint. And it’s not surprising that the gradient turns out faded. But if we adjust the values ​​of the black side of the gradient, and add a yellow and magenta channel to it, the gradient will become bright and saturated.

The situation is changing in the same way on the channels. Now we have the Yellow and Magenta channels as solid colors. And black is a decreasing gradient. At each segment, black is mixed with 100% red, resulting in a rich shade.

Simulating CMYK channels

It is quite possible to create your own image using CMYK. And now we will do this with you. Select absolutely any photo and convert it to CMYK (Image > Mode > Cmyk (Image > Mode > CMYK)).

Now let's open the Channels panel and see what's on our channels. It is very easy to imitate the combination of paints. Naturally, you can easily and quickly turn off channels and see how the color is combined, but doing all the work instead of Photoshop is much more clear.

Press CTRL and click on the yellow channel. By doing this you have loaded the selection. That is, a cast of the mask. Selection - half mask. Therefore, switch to the workspace and create a fill layer Layer> New Fill Layer> Solid Color (Layer> New Fill Layer> Color...).

In the Color Picker window that appears, select CMYK values ​​- C0M0Y100K0

Since we had an active selection when creating the layer, the layer was created with an automatic mask. But the mask is filled in backwards. To make it the same as the image, click on the mask icon and press CTRL+I Invert.

We created the first channel manually. Create your layers for the black, blue and purple paint in the same way. Arrange the layers in the same way as in the channels. And of course, don't forget to invert each mask.

Now let's change the blending mode of each layer to Myltiply (Multiply). Myltiply mode simulates the overlay of paints on top of each other. It cuts off light pixels, leaving dark ones. And this is how the paint is mixed. The more paint, the darker the shade. And as a result, we get exactly the same image, made with our own hands.

Manually changing CMYK channels

CMYK channels are very simple. The more pigment, the darker the channel; the less pigment, the lighter it is. You can correct the information on the channel “by hand” using a simple brush. You must understand that the channel's operation is based on a regular mask, which hides some of the light information in some places and reveals it in others.

As an example, I chose a colorful sky, in which the blue channel dominates at the top, yellow in the center, and purple on the sides. But knowing how channels work, you can easily fix this at the most basic level. Color correcting channels. It is clear that in order to remove pink, you need to lower the values ​​on the magenta channel.

Make a CTRL+click on the purple channel, and select this channel to work on its mask. Select a large soft-edged brush with white color. Set the brush's invisibility to about 25% and begin to lighten the magenta channel mask, stroke by stroke. You will see the color pink literally fall from the sky.

To remove yellow, CTRL+click on the yellow channel, and again, without losing the selection, reduce its effect.

In no case do I advocate color correcting channels this way. For color grading in Photoshop, you will find more than 100,500 different tools. There is no need to make irreversible changes to the channels. If you think about ways to correct color, then editing channels directly is the worst. But for the purposes of this article, it was important to show that the nature of the channels is a regular mask, which can be adjusted manually by adding color pigments with a brush.

Now that we have dealt with the channels, let's move on to more advanced methods of color correction.

Color correction in CMYK

For example, let's choose the same photo of the sky. Actually, in Photoshop there are 100,500 filters and color corrections to change colors without interfering with the channels. And the whole point of these filters comes down to the fact that they regroup the information on the channel. As an example, I will choose color correction - Chanel Mixer (Channel Mixing).

It is not difficult to guess that this color correction is tailored to change the saturation of channels. In the RGB color space, this filter may seem very complex because the RGB mixing principles are more complex to perceive. But when it comes to paints, everything is much simpler. In the photo we have 4 color areas. I'll take a pipette and sample the canals.

• In sample 1 we have a dark blue color. And we see that dark blue is obtained from the combination of cyan and purple paints.
• Sample 2 shows the color blue. And indeed, apart from this paint, no others are used.
• The purple areas in sample 3 are due to the prevailing purple paint.
• And the dull greenish tint in the middle was created due to the fact that a little yellow paint was mixed into the weak blue channel.

How to achieve exceptionally blue skies? It's simple. Reduce the influence of third-party paints. By reducing the magenta, we will remove the purple colors on the bottom and the dark blue on top. By reducing the yellow, we will remove the greenish tint in the center.

Chanel Mixer color correction makes this easy to achieve. All you have to do is choose desired channel, and reduce its impact. If we compare paint samples after applying the channels, we get a completely different result. Now all samples are dominated by blue paint.

Face color correction in CMYK using curves

Everything is simple with the sky. Removed unnecessary paints and that's it. But what if the photograph is more complex? If the channels contain not just shades, but details? Simply remove shades when all the details of the sky are in the blue channel. But what about more complex photography? If you know how paints interact, then it’s much easier to correct color correction. And the better the print result will be.

In the photo below we have the actor's face. The purple muzzle and overall blue color immediately catches the eye. But if we think in CMYK paints, then we understand that blue is due to the prevalence of blue paint, and redness is due to excess purple. Think gradients that intersect randomly and muddy grey-brown-crimson shades. So in this photo there are dirty mixtures that we need to clean.

If we take samples from the actor’s skin, we will get the same picture. Light gray-brown-raspberry and dark gray-brown-raspberry. And CMYK channels testify to the reasons. 37% blue 45% purple 20% yellow. So the result is almost gray, with a purple tint due to the purple channel.

It’s easy to correct the situation if you understand the principle by which paints are mixed on paper. For this adjustment, I'll select Curves and create a new color adjustment layer. First of all, let's get rid of the exposure to blue paint. It is she who creates blue and grays colors.

And the photograph began to sparkle with purple colors. The reasons for this are clear. The blue paint held back the purple. Now she is gone and the photograph is filled with a purple channel. Let's switch to Magenta and change its curve as well.

There is now a distinct yellow tint to the photo. And this is also understandable. After all, we removed the cyan and magenta channels, leaving the yellow one, which we will correct after them.

After which I slightly increased the contrast of the black paint. And here is the final result.

You can compare the results of the composition of paints on the face and glove yourself. Instead of 37% blue, we have 9% Instead of 50% purple, we have 28%. And the skin color stopped being purple.

I really hope that this article was extremely useful for you and now such an expression as CMYK does not scare you. Well, I, in turn, will continue to write articles on the topic of channels in Photoshop. Next up is Lab Color. Have a nice day and see you for the next articles.

How to convert rgb to cmyk, Convert rgb to cmyk, Convert rgb to cmyk, How to convert rgb to cmyk in Photoshop, Convert color from rgb to cmyk, How to convert rgb to cmyk in Corel, Convert an image from rgb to cmyk, How to convert rgb to cmyk in coreldraw, How to convert rgb to cmyk in Illustrator, How to convert rgb to cmyk in illustrator, Photoshop cmyk, rgb conversion.