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In this exercise, I'm going to demonstrate to you the Channel Mixer, a really, really great function, when you have bad channels inside of an image. But first I want you to note something about the title bar up here. Notice Dive master.jpg, its title bar ends with an asterisk. You can see that outside of the parenthesis. That means of course that I have unsaved changes, so no surprise there because I've been playing with this image. But there is no asterisk on the inside of the parenthesis this time, whereas there was at the outset of the previous exercise.
Well, that's because we started working in sRGB. Then we took the image into Lab, lost the asterisk as there is just one Lab mode, then, when we converted back to RGB, why Photoshop went ahead and converted to our preferred RGB space, that we specified in the Color Settings command way back in the fundamentals part of the series and that is Adobe RGB, so this image matches our specification in the Color Settings dialog box, so no need for an asterisk. If you've working along with me, press the F12 key, which reverts the image, of course, to its saved appearance here and returns us to the very, very awful version of the image, but here is what we're going to do. I'm going to take you over to the Layers palette because we're going to heaping on a bunch of adjustment layers throughout these exercises here. Then go to the Adjustments palette, of course, and note this guy right there; he is the Channel Mixer.
Now I would like to joke that Adobe stole this command from me, and the reason I like to joke about that is because I have this thing called the channel mixer. It was actually called channel mixer just like this thing is. Note, Channel Mixer. And I have built it with a filter factory with this thing that shipped with Photoshop 3.0, way back, not CS, just regular old Photoshop 3.0, and it worked the exact same way, it did exactly what this filter does. It allowed you to bring information from the green and blue channels into the red channel and then information from the red and the blue channel into the green channel and then information from the red and green channel into the blue channel. So you can mix the channels up in other words.
Now their functions way better as we'll see and it's applicable as an adjustment layer and of course just coincidently my filter is no longer compatible with Photoshop. Anyway, I'm going to go ahead now to Channel Mixer, you too to this image if you're working along with me and there it is. I might as well name it actually and I just double-click and we'll call this one make red because we're making a red channel with it. Now, you can either mix a monochrome image if you want to by clicking here. That means you'll mix the grayscale image using whatever ingredients you want, whatever amount of red, green and blue that you like and that's an interesting thing to do. I do document by the way the Channel Mixer in great detail in my Photoshop CS3, right now Channels and Masks series, which I may update some time in 2009, but it's mostly applicable and of course all the information about the Channel Mixer, except for where the color adjustment layer is, is applicable to CS4.
I will go into all kinds of detail by using monochrome, but no detail whatsoever about inventing a channel out of whole cloth like we're doing right here. So you can put things into the red channel, the green channel or the blue channel. In our case, we don't need to mix the green channel because we have already got one and we don't need to mix the blue channel because we have already got one. We want to focus entirely on a red channel right there. So that's our only concern. We do not want to turn on Monochrome, because you know if we do we'll get that. That's not good. So turn that off. Notice now, thanks to clicking on Monochrome, it has now gone ahead and applied 40, 40, 20 across the board to all of the channels, which is of course rotten actually because there is no way in heck if we'd want that to occur.
That's why we can come down here, Reset to adjustment defaults and click on it and hopefully, yes, it brought things back. Because otherwise, that was going to be pain in the neck and we would have to throw away that layer. All right, so we can mix in any amount of red we want, any amount of green, any amount of blue and then we have Constant, and Constant is going to add a constant amount of some color or subtract the constant amount of luminance. So in other words, it's going to make all the colors darker or all the colors lighter and there is no way in the world you'd want to do that on a normal basis. So you almost never and I have to say I never have used the Constant slider ever.
No we are not going to be doing it for this because this wouldn't help us. This is what we're going to do. We're going to take the contribution of the red channel down to 10%, which may seem like well, why even have to contribute anything? All it's doing is contributing to is the label on the back of the dive tank. But it's out of courtesy in part and also because it is making that contribution to the label on the back of tank so I just go and leave it to 10%. I'm going to take the green contribution pretty high. I'm going to take it up to 60% and notice that Photoshop is saying hey, you now have a total of 70%.
What you want is a total of 100% presumably, in order to build a proper channel. So then let's come down to blue and I'm pressing Shift+Up Arrow by the way to raise this value ultimately to 30% and now we have a total of 100%. It's like hey, good job. If I go too far, if I raise it another 10%, it's going to say, ding, ding, ding, no, no, you went to 110%, that's no good. Now it's not necessarily bad, sometimes it does work out to advantage. In our case however, it doesn't. So go ahead and take this down to 30, so we've got 10 for red, 60 for green, and 30 for blue and we have now invented a red channel; would you like to check it out? Why not? Click on the Background layer, then go to the Channels palette and then let's go through our channels, I'm going to hide the Adjustment palette. Here is red, all right, we've got ourselves a red channel, very respectable red channel given that this is green. I mean, no body has got any shadows right now, and this is. So we didn't change green or blue, all we did was change red and we just grabbed some data from the green and blue channels of luminance and put it in there and that gives us this effect here.
Now, the interesting thing to note is it's nowhere near what we eventually want because it would be great to have some shadows in this image. What a heck! But it is not half bad I the color department. His legs are brown and then his fins are sort of purplish, but that's close to blue, they're sort of violet color or light violet and not half bad, we have some distinction there in the labels that we are going to go ahead and keep and the tank is looking a little more neutral than it was in the past and he has got some yellow bands on his wrist and I just have to note he did indeed have some sort of orangish yellow band that he was wearing.
So we're just getting closer now. I have no memory really, what's the color of the coral was. But I bet it was pretty darn and warm, I mean, it looked better than this. So, what I'm trying to say is that's the good first step, believe it or not, it seems like sort of a puny first step but we've gone from this after all to this and we have made ourselves a red channel, thanks to that Channel Mixer function which is so great here inside of Photoshop. In the next exercise, we are going to discover shadows suddenly inside of this image with the application of a Levels adjustment layer. Stay tuned.
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