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In this movie we are going to cover how to create alpha channels. Now, the easiest way to create an alpha channel is to be in the Channels Panel, and simply click on Create New Channel. Now, that creates a totally black channel which means it will have no effect at all, it's totally black. The entire image is protected. Now that we have this blank channel, we can start to draw into it to do things like let's just say we create this little swirl like this. So now I can come over here, load that channel, and we'll hide the marching ants, so we don't see those, and I can go in there and say let's go and colorize that.
So, I'll go to Hue/Saturation, Colorize, increase the saturation, and you see that, that area is being controlled inside the alpha channel. That's the quickest way of creating one provided you have nothing in mind from the image to create that alpha channel. Now, another way is to have something selected. So, what I'm going to do here is I'm going to select this rock, because in the exercise, I have an alpha channel already created for this rock. So I have that, and I'm going to go over here and say Save Selection, where I have the ability to save the alpha channel, and give it a name.
Now, another very important thing to look at this window here is that there is the document. You will notice that I can actually send it to a new document. So, the alpha channel does not have to reside with the actual file. So, you are not limited to the number of alpha channels in a particular image or you might want to have say a couple of 100 alpha channels that you don't want your client to see. So you can put all the alpha channels for a particular file in a completely separate file, and that way, you could use them. You could also send it to a new channel or you can actually just bring it in, and replace an existing channel.
So, if I click on Alpha 1, which is the little swirl I made, and you can see it down here in the panel, it will replace that particular channel. So now that I have it, I click OK, and there is the rock. Now, once it is there, I deselect it, and I go to that channel, and I can see the RGB on top of it. You notice its showing up as a quick mask. Now, if red is not a good color to see the stuff behind, you can double-click on it, which brings you up to the options, which allow you to name it again or choose a different color.
So, I can go in here and say use green, and increase the opacity, so I can see more of it and so on. So there, now it's using green. So now once I have that, I can come in here, get in real close, and refine this mask to get it just the way I want. Remember that white exposes, black protects. So, if I paint with black, I'm going to be protecting. If I paint with white, I'm going to be exposing. So now, I can go in there and very specifically, go in there and say I wanted to get these little areas, and start to paint my alpha channel the way I want it.
And once I have all those areas exposed and just get just how I want it, I can go in there, and then I have an alpha channel which will allow me to select this rock as you will see in the various exercises where I use that. Now, sometimes you can pull an alpha channel from an existing image. Now, this is without selecting it. I'm going to redo what I did in that particular exercise where I used this waterfall as a waterfall falling from the high cliff. I'm going to look at the existing channels to make it easy, because this is not an easy thing to select on its own.
So, I'm going to look and see where I'm going to have my contrast. Is it in the red? Is it in the green or in the blue? The blue, the blue is giving me the most contrast. You can see how white it is here and how gray the rocks are as opposed to the red where they are fairly even and the green where they are pretty close, whereas the blue is giving me a strong contrast. So, by taking the blue and duplicating it, I get blue copy. Now, the image did not get any bluer, because remember, the alpha channel has nothing to do with the actual image, it is simply a mask.
So, in that blue channel, I can now go in there, and we'll bring up our levels. And I can go in there and take all my midtones and darken them, and take all my dark tones and darken them, and make those whites stronger, see. Click OK, then all the grays that are left, I can quickly eliminate those. Press F here so I can get a full screen, and I can go in here, and I'll select this entire area up here, and I'll just say, fill it with black. And I can take this entire area here and say fill it with black, this whole area here and then down here.
So now I can be a little more selective and go in here with a brush and paint these areas to black, and there you'll see that I'll now have an alpha channel that exposes just this water here. So, I can do things to it in the image. So, once I have all my water selected right there just, like so. I can now go back to the image, load that alpha channel which selects the water. So now, I'm going to just hide those marching ants so we can easily see what's about to happen.
So I can in there and say let's colorize this. Let's throw a little tone in there. Let's say we throw a little red in there. We could just make it red, see. Do anything we want to it, or make it a little lighter, make it a little darker, whatever. If we want to throw a gradient through there, we can, because we'll just throw a nice little gradient so it's water turning into blood or whatever. Now, whatever we want to do there, we can because the water has been selected from the rest of the image. And in that particular case, we use an existing channel to make our alpha channel.
So creating alpha channels has many different ways, but the uses are infinite.
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