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In this exercise I'm going to demonstrate another one of the little-known, little-used Blending Options inside of Photoshop. This one allows you to turn layers on and off between channels, and also show you something of a practical application inside of a CMYK image. So I've got this file right here, it's called Knockout.psd. I'm going to make a couple of changes here. I'm going to turn off this dark stars group, so that we're seeing the wrestlers directly against the parchment background. I'm going to double-click on an empty portion of that wrestler's layer, in order to bring up the Blending Options dialog box.
If you press dekeKeys, by the way, you can also press Ctrl+Shift+O, Command+Shift+O on the Mac. Notice these Channels check boxes right there. Probably, never used them, but watch what they do. If I turn off Blue, for example, then the image seems to turn kind of bluish on me. If I by contrast go ahead and turn off Red, then that makes the image even more red. Why in the world is that? Of course, if I turn off Green, we see it turn very, very green.
Well, let me show you what's going on. I'll just turn off Blue. We'll just see what this composition looks like without Blue. It's just affecting this one layer, notice that. I'll switch over to the Channels panel. If I switch to the Red channel, sure enough, we see the wrestlers. If I switch to the Green channel, there they are. If I switch to the Blue channel, they have mysteriously disappeared. Because the parchment is bright, and we're not seeing the darkness, that's normally associated with the wrestler's suits, they end out turning very blue.
So they brighten up in the Blue channel and we see that blue in the composite image. Now that might certainly make you scratch your head, and go, why in the world would you ever want to do that? Possibly, it'd be nice to have channel by channel opacity control. But instead, you have the option of just making the entire channel transparent. What's with that? Well, imagine that you want to overprint some black text, which is not normally something you can easily do inside of Photoshop. Well, you can do it this way. But you'd have to be working inside of a CMYK image.
That brings up a good point, which is, what in the world happens to all these blend modes when we switch over to CMYK? The answer, the short answer is horribly disastrous stuff. Blend modes do not survive conversions between different color modes very well. But let me show you what's going on. I'll switch over to this variation of the image. This is currently an RGB image. You can see that we've got Red, Green, and Blue channels. We've got all kinds of different blend modes that are being applied throughout this image here. Let's say we want to convert to CMYK.
Well, I'll go up to the Image menu. I'll choose mode, and I'll choose CMYK Color. I'm going to get lambasted by some alerts at this point. First of all, I'm going to be told that I've got a smart object going. That's the stars layer that has the Lens Flare effect applied to it. Do I want to Rasterize that smart object? I'm going to say no, because generally speaking, I would try your conversion without rasterization, without flattening the first time around, and see how the composition fares. So I'll say Don't Rasterize. Then I'll get this other rather upsetting error message that says, hey, Changing modes will discard an adjustment layer; because there is an adjustment layer in there somewhere that's just not going to survive the transition.
Do you want to change the mode anyway? So you can Cancel, or you could say Flatten. That will preserve the appearance of the image. If you click Flatten, you will have the best looking CMYK image you can have. It'll look as close as the RGB composite as possible, that'll fuse all the blend modes together, so that you'll get halfway descent transitions, but you will no longer have the layers available to you. You won't be able to take advantage of this overprinting technique. So I'll click OK. In other words, I don't want to do any flattening and my image ends up looking like that.
Well, I would say, that was not the most successful conversion. I mean, there is so much wrong with this at this point. Everything is dimmed down like crazy. We can see the border around the light bulb. It's just a total mess. Well, one of other things that's going on here, I'll go ahead and scroll down and I'll twirl open this future stuff group once again. Notice my stars layer. What happened to the Lens Flare effect? Well, if I expand my list of Smart Filters. We'll be seeing Smart Filters in the future chapter of course. But notice it's turned itself off.
We have this warning that says that Lens Flare cannot be applied to this document. Well, Lens Flare doesn't work in CMYK. So that didn't work out very well for us. So you know what, let's go ahead and press Ctrl+Z, Command+Z on a Mac to undo that modification. So we're back in RGB. Let's go back up, Image>mode, and CMYK Color once again. This is the kind of thing you have to do when you're trying to decide what to do with your blend modes, when you're converting between color models. In this case, I'm going to say, you know what, I got to Rasterize that smart object.
I've got to convert it to pixels, so we keep the Lens Flare effect. Then the question becomes, do you want to go ahead and keep your layers. I'll say OK. It's telling me I'm losing an adjustment layer. So I have to figure out what that is. Is it that Levels layer right there? Is it, I think there is Brightness Contrast layer in there someplace? So I'll go ahead and click OK. Sure enough that darken layer went away. So I lost my levels. I'm keeping my invert layers; that's interesting. I'm keeping my Lens Flare Effect this time. That's nice. I still have this strange thing around the light bulb. I'll go ahead and twirl open my future stuff layer right there.
I didn't lose this brightness contrast layer, but it wasn't applied either. So it wasn't turned on. Notice this invert layer right here. If I turn it off, then we have this extremely bright parchment and I just want to show you something. If I switch over to the Channels panel now, and click on the Black channel, there is barely any black associated with that parchment. Invert, I was telling you an Invert adjustment layer is going to invert on a channel by channel basis. So when you invert this Black channel, you're going to do so with a disastrous effect. You're just going to wipe out the luminance inside of this channel.
It's going to turn absolutely black. Then you're building the stars and the other stuff on top of it, but that means you're starting with a very dark layer in the first place. That's one of the reasons that this image is darkened up so considerably. All right, so I'll switch back to CMYK, the CMYK composite. I'll go ahead and turn invert back on, that invert adjustment layer. But I'll double-click in an empty portion over here on the right-hand side to bring up the Blending Options. I'll turn it off inside of the Black channel, so we're not inverting the contents of the Black channel. That fares better.
Now I'm not going to tell you that that's a good match. But it is a better match than what we had before. All right, but that's still not a good match. So I'll press Ctrl+Alt+Z a couple of times to back step to the RGB image. So what would appear, I'm going to have to flatten a few layers here. I'm just going to go ahead and grab darken, because I know otherwise I'm going to lose it. So I'll click on it, and I'll Shift+Click in the Background. So this entire range of layers, including this future stuff group right there, I'm going to fuse it together by going up to the layer menu, and choosing Merge layers, or pressing Ctrl+E, Command+E on the Mac.
That goes ahead, and creates a fusion of just about everything inside of this composition, except for the light bulb elements, because I want to show you something there, and of course, the text elements as well, because we want to create that overprint. All right, now I'll go up to the Image menu, choose mode, and choose CMYK Color. Photoshop is still going to give me a hard time about something. Changing modes can affect the appearance of layers. Well, yeah, we are pretty familiar with that by now. Don't flatten however, so click on the Don't Flatten button and that's not bad. Look at that.
This is the RGB version of the image and this is the CMYK version of the image. That's as close of a match is we're going to get, because we're switching from these richly saturated RGB colors to CMYK where those colors are effectively out of gamut. However, we do have a problem with the light bulb. Notice that we can see the rectangular edges around the light bulb. I'm going to explain why that's happening, how to fix that effect, and how to overprint your text in the next exercise.
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