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Photoshop CS5 One-on-One: Advanced, the second part of the popular and comprehensive series, updated for CS5, follows internationally renowned Photoshop guru Deke McClelland as he dives into the workings of Photoshop. He explores such digital-age wonders as the Levels and Curves commands, edge-detection filters, advanced compositing techniques, vector-based text, the Liquify filter, and Camera Raw. Deke also teaches tried-and-true methods for sharpening details, smoothing over wrinkles and imperfections, and enhancing colors without harming the original image. Exercise files accompany the course.
Recommended prerequisite: Photoshop CS5 One-on-One: Fundamentals.
All right, for those of you who maybe interested I've gone ahead and saved out versions of all three of the grayscale images. So you already know about Grayscale composite.jpg that's the fused version of the RGB image created just using grayscale command. Then there is Blue to gray which is that Blue channel from the RGB image saved out as an independent grayscale image. Finally, there's Luminance only.jpg, that's the one we just created in the previous exercise, the Luminance channel from the lab image.
So you have three different grayscale images. You can take a look at inside of that 18_black_white folder. I am going to return to my Agrarian gothic.jpg file which is the full-color version of the image. Then I will go up here to the Arrange Icon and choose Consolidate All or if you loaded dekeKeys, you can press Ctrl+Shift+A, Command+Shift+A on the Mac and tab back my toolbox and option bar and panels and so on. In this exercise, I am going to introduce you to the Channel Mixer, which is a way of mixing the various color channels with each other.
Now it's a fairly geeky command to start with, because you can get all sorts of wacky sometimes psychedelic effects if you're interested, but over the course of these next couple of exercises here we will settle things down. I will just show you what it can do at first and then we'll see some practical applications for the command. Because one of the really great things you can do is you can mix your very own custom grayscale/black-and-white image. All right, so here I am in the Layers panel, there is a couple of different ways to apply the Channel Mixer.
One is to go up to the Image menu choose Adjustments and then choose the Channel Mixer command. That will apply a static application of the Channel Mixer. I don't recommend you work this way, because once you start playing around with this command a little bit, you will definitely want to tweak your settings over time. So you're going to want to keep this option live as an Adjustment layer. So the better way to work is to bring up the Adjustments panel. I will do so by going to the Window menu and choosing Adjustments. If you loaded dekeKeys, you have F10 to bring up this panel right here.
This guy, the last icon in the second row takes you to the Channel Mixer. So I am just going to click on it and that creates an independent Channel Mixer layer. Notice what you have here. You've got the thing that says Output Channel and what you're doing basically is you're dumping some mix of the various channels into a channel. So in other words, in this case we are modifying the contents of the Red channel and then we could turn around and modify the contents of the Green channel and then move on to the Blue channel. If you want to add some more keyboard shortcuts to your array of shortcuts rambling about in your mind, now these are ones we've seen before and they work the same inside the other Adjustment layer panels, but basically the idea is Alt+3 or Option+3 is going to take you to the Red channel, Alt+4 or Option+4 is going to take you to the Green channel, Alt+5 or Option+5 is going to take you to the Blue channel.
You can't access the RGB composite. So there is no Alt+2 or Option+2 with the way there is inside the Levels or Curves panel of the Adjustments panel right here. Now the thing to bear in mind is we are working inside of an RGB image that's where Channel Mixer works best. You can use it inside of CMYK images as well. It's pretty much of no use whatsoever inside the Lab mode and there is not anything you can do inside the Grayscale mode either, because you just have one channel. So we are taking the optimal approach here and this is the most common approach too, because most of the images you will be editing are RGB images.
Anyway, let's imagine I want to take the Red channel and I want to change it. I'm going to ask you just kind of bear with me and let this flow over you at first. It's going to make more sense as we get into it here. I am going to switch to the Red channel. That's my default channel in the first place, leave Monochrome off. That's for mixing black-and-white images. We will come to that in a couple of exercises, but for now just leave that option off. I'm going to switchover to the Channels panel and I'm going to click on the Red channel so that we can see our modifications as applied to just that one channel for now.
I am going to take the amount of Red channel, let's say just for the sake of demonstration, I am going to take it down to 50%. That means we're making our Red channel much dimmer as you can see and you can look if you want to at that little thumbnail at the top of the Channels panel, which will show you what the RGB composite is looking like more or less. But basically, the deal is by extracting a bunch of red from the image we are leaving a bunch of green and blue behind. So it's becoming quite turquoise and we can see that just by clicking on the composite if you want to.
So there is the image in progress. Well, that's not what we want at all. Let's go back to Red for a moment. Notice this guy right here that says Total and it says 50% down there. You want that Total to hover right at 100%. It doesn't have to be exactly 100%, you can let it go down to 97% let's say or let it rise to about 103%, but if you go too much lower or too much higher you're going to either end up with lackluster colors out of this channel. You're not going to be taking sufficient advantage of it or you're going to end up blasting the colors too bright and you'll be clipping your highlights.
So you don't want to do that. Now notice I could take his Green channel, let's say I take it up to 55%, like so. So we are adding 50% of the Red channel, what was formerly the Red channel anyway to 55% of what was formerly the Green channel. It still is, we haven't modified the Green channel yet, but as a result we have a Total of 105%. We have a little warning right there that's telling us that our total is greater than a hundred and what that means is probably we are clipping highlights and we can actually see here in the Histogram panel. If you can't see your Histogram panel, go to the Window menu and choose Histogram.
But you can see in the panel that we are clipping highlights just to make sure that's accurate, I will click on this little Update icon and sure enough we are clipping a lot of highlights right there. That's not something we want. So when in doubt, just make sure that this Total adds up to 100%. So I am going to take the Green contribution down to 50% and as a result we have 50% red mixed with 50% green to create our new Red channel. Now what that means is that we are darkening the channel. Why is that? Well, remember because this was a portrait shot, we were starting off with the Red channel being the brightest, the Green channel being the next brightest, and the Blue channel being the darkest.
So portrait shots pretty much invariably work that way. That is right in a row they are Red brightest, Green next, Blue darkest. So by sacrificing some of the redness and adding some greenness we are actually adding the second brightest channel to the brightest channel which is going to create a kind of compromise between the two which is going to be slightly darker. So if you want to see the difference here, I can click on this Eyeball icon at the bottom of the panel and that will turn off this Channel Mixer layer for just a moment. So this is the original Red channel and this is our new Red channel which is slightly darker. Interesting! All right, so, and like I said I'm just asking you to bear with me here, as we play around with this, and you'll get a sense of what we're trying to achieve more or less when we are done, because it's a little bit hard to anticipate at this point.
All right, we will go ahead and switchover to the Green channel here and this time around I am going to say, all right, I'm going to take the Green channel contribution down to 60% which is obviously darkening the heck out of this Green channel. Let's go ahead and check it out. It's become much darker now. So this was before if I turn off the eyeball, this is after and as a result now we have an image that has less green which means the contributions of the Red and Blue channels have become more important. So we have this kind of magenta image left as a result.
Anyway, I am going to switch back to the Green channel here. So we are viewing it independently and then I am going to add a fair amount of Blue channel. Notice I'm taking that up to 30%. So our Total is now 90. So the panel is doing the math for me. That means I need 10% more contribution from something. I'll bring that in from the Red channel. So have I darkened things or have I lightened them? Well, because Green is our second to brightest channel, and Blue is our darkest channel, we are bringing in a fair amount of blue and just a little bit of our brightest channel red. So we are probably darkening the Green channel now.
So I will go ahead and turn off the eyeball. Sure enough before it was brighter, now it's darker, except, actually here in the hair detail, back in this woman's hair in the background. We can see that her hair is actually brightening up a little bit and that must be, because of the contribution of that Red channel. Or perhaps if we go back to the RGB image and we turn off this Channel Mixer for a moment, we can see that she's got very bright red hair. This is obviously an artificial color.
It's got some blue in it so by virtue of the fact we added a bunch of blue to the green channel, we actually did brighten her hair. This is what the image looks like now if I turn the Eyeball back on. So we are developing a kind of brownish image at this point. I'm going to switchover to the Blue channel this time inside the Channels panel. Then I'll switch my Output Channel to Blue. I am going to go ahead and take Blue down to 50 this time around. We are going to brighten the Blue channel, because we're taking down the Blue channel's contribution. We are adding 50% combined of Red and Green, so that can't help, but brighten that Blue channel.
Of course, different areas of the image are going to brighten differently, but I am going to take the Green channel contribution up to let's say 40. So we've got 40+50=90. I need to add 10% more from the Red channel let's say and I'm just feeling my way through this. Now just to see what we've done, this was the before version of the Blue channel and this is the after version. We have definitely brightened up the channel, especially inside of the skin tones here and inside of her eye. Now if I go back to the RGB Composite image, this is what the original image looked like and this is what it looks like now.
So it has a much ruddier flavor to it. Thanks to the contribution of this Channel Mixer layer. So we'll go back to Layers panel, having closed the Adjustment panel here. So again, let's go ahead and scoot this over a little. This is before and this is after rendering up with a more monochromatic mix which tends to be the case when you add Channel Mixer. However, you can get some very interesting color combinations. You can actually subtract the contents of one channel from another and I'll show you how to do exactly that in order to achieve an extremely vibrant image in the next exercise.
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