Channels are just one incredibly powerful tool in Photoshop’s vast arsenal of image editing capabilities. They have a number of different uses, and are frequently my tool of choice for creating masks and selections, or to make slight colour adjustments to an image.
Today, we are going to learn how to create an interesting photo treatment using channels and colour spaces. We will move from RGB to CMYK to Multichannel and finally back to RGB again. All, with the purpose of changing the way that the images colours interact with each other.
I like this image because it has a nice blue sky and, great green grass and clear skin tones. This range of colours will work quite nicely for the effect we are going to try to achieve here.
So, then, get to work. First, though, here’s a preview of the final image.
Open the image in Photoshop. Our image was downloaded directly from the internet, so it is in RGB mode by default, since that is the native colour space of all digital cameras and the web. The first step, then, is going to be to convert the image to CMYK.
This is really just an interim step, so we don’t really need to worry about exact colour profiles here. Just go ahead and click Image -> Mode -> CMYK Colour:
If you’re wondering why we’re converting to CMYK, it has to do with the number of channels. In RGB mode, we have only have three channels of red, green and blue. To achieve the effect we are working towards, we want the four channels of CMYK mode. More importantly, though, using CMYK will help us maintain at least some integrity when it comes to our colours. You’ll see what I mean in the next step.
Now, don’t get too comfortable in CMYK mode though, because we’re not going to be staying here long. Next, Go ahead and select Image -> Mode -> Multichannel. This take us out of CMYK mode, but will leave us with with unmanaged cyan, magenta, yellow and black channels.
You may notice a slight change in the colouring. This is nothing to worry about, since we are going to be playing with the channels anyhow. However, this is where the initial conversion to CMYK helps. If we had converted directly from RGB to Multichannel, this change in colour would have been much more dramatic. This way, we stick much closer to the original.
If it’s not already open, reveal the Channels palette by selecting Window -> Channels. Notice that we still have the same channels as we did in CMYK, with the exception of the combined CMYK channel. In multichannel mode, we simply have multiple channels, each with its own colour, all working together to create a single coloured image. This is exactly what we are going to take advantage of here.
Double click the cyan channel to bring up the Spot Channel Options dialogue.
This might be new to you if you haven’t worked in Multichannel mode before. Basically, we have four unmanaged colour channels, meaning that instead of having predetermined colours combinations like CMYK or RGB, we have almost unlimited control of how me mix our channels. So, next you want to click on the little cyan box to bring up the colour dialogue.
Press the Colour Libraries button to change selection modes.
From here, select Pantone colour 3245 C, which is a lighter colour of blue, with just a hint more green than normal cyan.
Notice that this significantly changes the overall mix of the image, giving it a more green hue.
We want to do the same thing for the magenta and yellow channels, too. Simply repeat the Step 3, using the following values
- Magenta -> Pantone 216 C
- Yellow -> Pantone 5025 C
Notice that the strongest change comes when we change out the colour of our yellow channel to a pale rose.
The image feels just a little washed out, so our next step will be to add just a little more depth by tweaking the Black channel. Select this channel in the Channels palette, then select Image -> Adjustments -> Brightness/Contrast from the menu. Decrease the brightness by 15 and increase the contrast by 25, as shown here.
This will darken up the hair, and help bring out the depth of some of the shadows.
Okay, so now we have our basic colour treatment down. We could, theoretically, stop here and save the images. In fact, that’s probably a good idea, so go ahead and save.
Now I want to talk about Pantone colours for just a moment. You don’t have to use Pantone for the colours of your different channels. We could easily have mixed our colours in the colour mixer, using CMYK, RGB, Lab or HSB. However, I wanted to use Pantone because, this way, we could theoretically take the image directly to a commercial printer if we wanted a large run of this image. Instead of using Cyan, Yellow, Magenta and Black inks, the printer could use the specific Pantone colours that we have chosen here in order to print this image exactly according to our colour mix.
But let’s assume that we are using this technique to create an image for a website. Clearly we need to convert back to RGB mode. Go ahead and try a direct conversion. You should get something like this:
We’ve basically reverted back to a more saturated version of our original image (which could be a cool effect, but is not exactly what we’re looking for). This is because we’ve moved from unmanaged colour back to managed colour. In Multichannel mode, we can associate any channel with any colour. In RGB mode, though, the first three channels are always going to be Red, Green and Blue, in that order. Thus, when we switch modes, our Pantone colours are converted to standard RGB channels.
So undo your conversion, because I’m going to show you a little trick for re-composing your image using blending modes.
First, open a new document with the same dimensions as our existing photograph – in this case 4368 x 2912 – and call it something like Re-composite. Make sure that the new document is set to RGB mode.
Now, go back to our Multichannel document and select the top-most channel. Right click and chose “Duplicate Channel” from the contextual menu.
In the dialogue box, select our “Re-composite” document as the destination and press OK.
Switch back to the “Re-composite” document. With the new channel added (and automatically turned on), the document should look something like this.
Now, select the RGB channel, which should automatically turn off any additional alpha channels. The greyscale image should disappear, leaving a plain white canvas. That’s what we want. Next, add a new layer and change your foreground colour to Pantone 3245 C, which was the colour of the first channel in our Multichannel document. Because we’re working in RGB mode, the colour will actually be the RGB equivalent of this Pantone colour.
Now, we want to create a selection from our duplicated channel. To do this Command-Click (PC: Ctrl-Click) on the channel preview.
Select our new layer in the Layers palette and press Option-Delete (PC: Alt-Delete) to fill in the selection with our selected Pantone colour.
That’s one channel done, but before we continue, I would like to take a moment to talk about channels and selections. In RGB mode, we are working entirely with concepts of light, which uses additive colour. Basically each channel tells the display how much of each type of light to emit for each pixel, thereby creating the illusion of colour. In CMYK mode, we are working with concepts of inks, which use subtractive colour. In this case, we are imitating the way coloured inks would work together to create the illusion of colour on a printed page.
The importance here is this – in RGB mode, colour is represented in white, while in CMYK mode, colour is represented by black. As such, the way that we create selections is directly effected by the type of channel we are working with. I like to think of them as light channels and ink channels.
With and light channel, selections are made on the colour, as represented by white. Conversely, with ink channels, selections are made on the colour, as represented by black.
To bring this back around to the matter at hand, because our new duplicated channel is an ink channel (Multichannel always works based on inks, not light), the selection we created was based on the blacks, and we could simply drop our color onto the layer based on that selection. However, if we had created a selection based on a light layer, we would have had to invert our selection before applying any colour to our layer.
With that in mind, repeat steps 6 and 7 for each of the other channels in our original Multichannel document, using the matching colours (Pantone 216 C, Pantone 5025 C and Black) to fill each layer. Also, when filling the black layer, trying using the RGB equivalent for CMYK plain black (R:35 G:31 B:32 or #231f20).
By the time you have created your four layers in the new “Re-composite” document, which are essentially working as proxies of the four channels from our Multichannel document, your canvas should look something like this.
Unfortunately, this looks nothing like what we’re going for. So here’s the trick – we want to get all four layers working together using blending modes. So, select each layer, and change the blending mode to Multiply.
Voila! The colours of the four layers are now blended together over the white background, in much the same way that they would be if we were printing with our four Pantone colours.
Now, we’re almost done. The transition between our Multichannel document and our new RGB document is not quite perfect. So, we’re going to use an adjustment layer to get things a little closer to our original. Add a new Hue/Saturation adjustment layer with the following settings
- Reds -> Hue: +3 / Saturation: -29 / Lightness -23
- Cyans -> Hue: -14 / Saturation: +45 / Lightness: -25
- Magentas -> Hue: +67 / Saturation: -29 / Lightness: -17
It’s not perfect, but this gets us pretty darned close to where we want to be with this image.
Step Ten (Optional)
Our image is pretty much finished at this point, but if you want to take just one more step, we can really bring some nice contrast by using a little trick that I picked up from GoMedia Zine.
Select all of your layers, including the background, and duplicate them. With the new layers still selected, merge them all together. Select Filters -> Other -> High Pass from the menu. Use the default options in the dialogue box and press okay. This will transform your layer to look like this
I know, this looks absolutely horrid. Don’t worry, it will be alright. All we have to do is change the blending mode to Overlay.
Isn’t that much better?
It’s up to you whether you want to use this step or not. Doing so can really sharpen all the detail, without really adding any real jaggedness or noise to the image. However, if you want a softer look to your image, feel free to skip this step.
Your Turn To Talk
So there you have it. This is a really simple way to create a cool photo treatment by working with Photoshop’s different colour modes and blending modes. There are tons of different ways of composing photos. For this tutorial, I chose to move from a fairly vibrant image, to a more faded and subdued treatment of colours, but you could easily create all sorts of vibrant, super-saturated images by using different colours.
I hope you found this useful, and that you learned a thing or two about working with channels. Please let us know what you think! :)