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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, I'll show you a couple of additional ways to save selections as alpha channels inside Photoshop, both of which I find to be more convenient than choosing the Save Selection command. I'm still working along inside the image called toolman.jpg. I have not saved a catch-up file for you this time around, the reason being that you and I are going to save this image along with its alpha channels in the very next exercise. Now that we've selected the goggles, the next trick is to select the areas that will represent the rays coming out of those goggles.
So we'll start things off, once again with the Quick Selection tool. Go ahead and drag inside that first goggle like so, and I'm also going to zoom in, so I can better see what I'm doing here. And next, I'll switch back to my Rectangular Marquee tool, which you can get by pressing the M key, and then go ahead and press the Shift key. What I recommend you do is align your cursor with the bottom of the animated selection outline like so, and then drag upward. And because you have the Shift key down, you are adding to the existing selection outline.
Now you want to make sure that the top of your new selection is aligning as closely as possible with the top of the goggle selection. And I'm going to go ahead and drag my cursor out to about here. Ultimately, we want the selection to extend all the way to the right side of the image. But if I invoke an Auto-Scroll, then I'm not going to be able to see the goggles anymore, and that will prevent me from properly aligning the selection outline. All right! That looks pretty good to me. I'll go ahead and release in order to finish off the selection. Now let's save this selection as an alpha channel by dropping down to the bottom of the Channels panel, and you'll see this icon that says, Save selection as channel.
If you click on it, then you'll create a new untitled alpha channel. If you want to name the alpha channel as you create it, then press and hold the Alt key or the Option key on the Mac and click on that Save selection as channel icon. I'm going to name this channel front and then click OK in order to add a new alpha channel to the list. Now I'll click on front in order to select it and then press Ctrl+D or Command+D on the Mac in order to deselect the image. All right! Now let's check out the quality of the selection here by zooming in on it. Again, it's very ratty in that area that was created with the Quick Selection tool.
It's very smooth in that area created with the Rectangular Marquee tool. But it does look like it extends perhaps a little farther upward than it should, because we have this little bit of a stair step there. So I'm going to select this region like so along the top and then slowly let this Auto-Scroll happen, so I go ahead and grab the entire top of the selection. And then I'll go ahead and press the D key in order to instate the default colors, which are white for the foreground color and black for the background color. So the opposite they usually are when you're working inside of an alpha channel.
Then press Ctrl+Backspace, or Command+ Delete on the Mac in order to fill that selection with the background color, which is black. All right! Now I'll scroll back over to the left side of the image. We have a little bit of junk down here at the bottom. I'll select that area; press Ctrl+Backspace or Command+Delete again in order to fill it with black. Now I'll click to deselect the image, and then I'll go up to the Filter menu and choose that very first command, Median, or you can just press Ctrl+F, Command+F on the Mac to smooth things out. Now, I'll go ahead and zoom out a little bit here.
Note that that goes ahead and smoothes both sides of the selection. So we end up rounding off the corners of the rectangular marquee. That's not actually a problem for our next maneuver here. What I want you to do is select this region like so, once again, using the Rectangular Marquee tool. So watch out for this area that's rounded around the goggles. You don't want to select that. You want to make sure the left edge of your selection outline goes through a straight-sided portion of the mask. And then press all the modifier keys, that is, Ctrl+Shift+Alt on the PC or Command+Shift+Option on the Mac, and go ahead and drag this selection all the way over to the right, so you no longer see those rounded corners. And that's it.
That goes ahead and extends the selection, that's exactly what we want now. Let's return to the RGB image by clicking on RGB at the top of the Channels panel and rerun those steps on the rear goggle. So I'll go ahead and grab the Quick Selection tool, drag inside the goggle, like so. Then grab the Rectangular Marquee tool, go ahead and zoom in, so I can better see what I'm doing. And once again, I'll Shift+Drag from the bottom of the goggle to the top like so, and release, in order to create that selection outline. Now let's see what we've managed to accomplish by converting the selection to a mask.
Now the technique I just showed you, that is clicking on that Save selection this channel icon, that is by far the best way, in my opinion to generate an alpha channel. However, you can also do so, I just want you to see, you can just go ahead and click on this Create new channel icon, or if you want to name the channel as you create it, you can Alt+Click on that little page icon to bring up the New Channel dialog box. That's an Option+Click on the Mac, and then we'll go ahead and call this channel rear and click OK. Now the reason I'm showing you this is sometimes I accidentally click on this button and I end up with this effect here, where I have a new alpha channel, it's named, it's ready to go, but Photoshop did not convert my selection to a mask. Well, that's okay.
Because you have the selection, all you have to do, assuming you've got the default colors, white for foreground and black for background, you just press Alt+Backspace, or on the Mac, Option+ Delete to fill that selection with white. Then go ahead and click off the selection and that is just as good, by the way, as any of the other techniques I've showed you. All right! I'm going to go ahead and zoom on in to my selection, so I can check out those just terrible edges right there. I also have a little bit of a hump at the top, but I'm not going to worry about that. I'm just going to smooth things out by going to the Filter menu and choosing that first command, Median, or I could press Ctrl+F, Command+F on the Mac.
Zoom out a couple of clicks here so that we can see the far right side of the canvas, select this region like so, so that I'm selecting through a straight-sided section, and then Ctrl+Shift+Alt+Drag or Command+Shift+Option+Drag on the Mac. And I have to drag that selection a couple of times in order to duplicate it all the way over to the right side of my canvas. All right! That's exactly what we were looking for. So go ahead and switch back to the RGB image by scrolling up the list and clicking on it, or if you prefer, you can press Ctrl+2, or Command+2 on the Mac. We now have an RGB image that also contains three alpha channels.
We need to save it to disk, and I'll show you how that process works in the next exercise.
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