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Photoshop Masking and Compositing: Fundamentals is the introductory installment of Deke McClelland's four-part series on making photorealistic compositions in Photoshop. The course shows how to make selections, refine the selections with masks, and then combine them in new ways, using layer effects, blend modes, and other techniques to create a single seamless piece of artwork. Deke introduces the Channels panel and the alpha channel, the key to masking and transparency in Photoshop; reviews the selection tools, including the Color Range tool , Quick Mask mode, and the Refine Edge command; and shows how to blend masked images so they interact naturally.
In this exercise, we're going to take a look at the No Color Multichannel mode. Now the Multichannel mode is really designed to house masks. So imagine you have four or five masks that you've created, you want to offload them to a file independent from the original image for whatever reason, then Multichannel would be the mode to use, because you're not forcing Photoshop to create some sort of interaction between the channels and deliver a composite color image. However, I'm going to show you this really cool use for Multichannel, how we can achieve an interesting effect and that way you'll get a sense of how Multichannel works as well as experiencing a new technique.
One, between you and me you're not going to find out anywhere else, but it's a really nice effect. We're going to start off with this file called Baseline toucan.psd. It's the same composition, but without the swatches and the labels, and we're going to change it into this file Alternative toucan.psd. And I suppose this is the kind of the effect you could try to pull off using adjustment layers inside of Photoshop, but I know of no other way than what I'm about to show you to get a result this different from the original in which the details are still in great shape.
All right, so I'm going to switch back to that Baseline toucan.psd file and I'm going to right-click on the Background image here inside the Layers panel and choose Duplicate layer. And then I'll change the Document option from Baseline toucan to New and I'll click OK and that creates a new flat version of the image. Notice that we have a Background image and that's it here inside the Layers panel. All right, now I'm going to switch over to the Channels panel and I want to be able to see my channels and color once again, so I'll press Ctrl+K, or Command+K on the Mac to bring up the Preferences dialog box then click on Interface and turn on Show Channels in Color and click OK.
And you can see we've got a Red channel, a Green channel, and a Blue channel in color. And I remind you, by the way, where the Red channel is concerned, for example, the darkest color is black and the brightest color is red which is exactly the opposite of cyan, which is the color complement to red. The whole purpose of cyan ink, by the way, is to absorb Red light and reflect back Green and Blue. And whereas cyan channel is concern the darkest color is cyan and the brightest color is white. I mentioned that because you're about to see that transformation.
When you go up to the Image menu choose mode and then choose Multichannel. Now Photoshop is going to ask you if you want to flatten the layers because you have to flatten the image to take it to the Multichannel mode. In our case our image is already flat so I'll go ahead and click OK. And now notice what happens, basically the image gets wrecked, because Photoshop takes those red, green, and blue channels and redefines them as Cyan, Magenta, and Yellow. However, it doesn't perform any conversion, so in other words not a single pixel in this image has been harmed.
However, this red channel looks quite a bit different now, because as I was saying, the darkest color has been remapped to cyan here in the Color Channel view and the brightest color has been remapped to white, but that's really the only difference. However, when you turn on these various channels the image just looks terrible and that's because for one thing we didn't convert the colors which is necessary if you're going to go from RGB to CMYK successfully. And we didn't generate a black channel which you need as well and the image is not being color managed. And we'll see what that looks like in a moment, but first we need to generate a black channel.
And we're going to do that by going up to the Image menu and choosing the Calculations command. Now this is a command that turns out to be very useful for high-level masking which is why we'll be using it time and time again in my future masking courses, but for now I just want you to go ahead and choose the command. I'm going to go ahead and move this dialog box over, change the first Channel option to Cyan which is the way it should be set by default, then change the second Channel option to Magenta and then change that Blending option from Multiply to Screen, and here is what's happening.
We're using the Calculations command to blend two channels with each other to create a new channel subject to a blend mode. So we're using the Cyan channel to brighten the contents of the Magenta channel and we end up getting this great black channel right here. I'll go ahead and click OK in order to create that channel unfortunately it comes in as another cyan channel that Photoshop is decided is a Spot Color, but we can resolve that by double-clicking on the channels thumbnail to bring up the Spot Channel Options dialog box, and then I'll click on that cyan Color Swatch to bring up the Color Picker, and watch what happens when I change the ingredients of this color.
I'll change the C value which is Cyan to 0, and then I'll change the K value and I want you to watch what happens to the name setting up here. I'll change that K value to 100 and Photoshop automatically renames the channel Black which is absolutely ideal. Then I'll go ahead and click OK and I'll click OK again and now we have ourselves a Black channel. And if you go ahead and drag up the eye column here in order to turn on all the eyeballs you'll see what that full- color image looks like, more or less, which is to say still quite tedious.
So I'd like you to switch to the Cyan channel and if necessary go ahead and press the D key in order to switch to the default colors. So Black is the foreground color and White is the background color and then press Ctrl+Backspace or Command+Delete on the Mac to fill the Cyan channel with white, and now we have a much better mix of colors. Again, it's the kind of thing you could try to attempt using the likes of adjustment layers. I just don't think you get there without causing the image more harm than good. However, we're still working inside of a multichannel image which means Photoshop don't know what to do with it, it can't print it properly, there is really no good way to put it to use until you convert it back to RGB which is actually a bit of an arduous journey which is why I'm going to show you how it works in the next exercise.
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