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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, we're going to take our mask so far, and we're going to selectively enhance its contrast using a combination of the Brush tool, along with a couple of different blend modes. I've saved my progress as Blue channel mask.tif. And the reason I used the TIFF format, by the way, is because we have an alpha channel, so JPEG is not going to work. We also have a flat image file. Notice all we've is the background here inside the Layers panel, which means that the TIFF format, combined with LZW compression, is going to produce a smaller, more efficient file than the native PSD format.
I'm going to switch back to Channels. Notice that the alpha channel is selected. Now, as I say, we're going to be completing this mask by hand painting inside of it. So your best bet is to go ahead and duplicate the channel at this point. So I'm going to go ahead and drag it, and drop it onto the little Page icon at the bottom of the Channels panel. Because, after all, when you're working with layers, you can make nondestructive modifications, but when you're working with alpha channels, there are no layers, so every change you make is technically destructive, especially hand painting, as you're about to see.
I'm going to rename this channel overlay painting, because we're going to be comparing a couple of different techniques. Then I'll go ahead and switch to the Brush tool, which you can get by selecting it, or pressing the B key. Notice that my Brush is set to 13 pixels, as by default, so it's very tiny. What I want to do is paint away the regions of her face inside the white silhouette, so I need a much larger, harder brush. So I'm going to right-click inside the image window, and I'm going to take the Size value up to a whopping thousand pixels, and then I'll take the Hardness value up to 100%, and I'll press the Enter key, or the Return key on the Mac, a couple of times in order to accept that change.
I want you to notice something. See where my cross-shaped cursor is? That little bit of gray right there? That's an area of revealed background. If I press Control+2, or Command+2 on the Mac, to switch back to the RGB image, you can see that we have some white background between the hair and her cheek. So we want to make sure to retain that area. However, everything else falls inside of her face, and therefore it needs to be painted away. I'll press Control+7, or Command+7 on the Mac, in order to switch back to my alpha channel at hand, and you can see that's its keyboard shortcut, because it's listed there inside the Channels panel.
Press the D key in order to restore your default masking colors, which are white for the foreground color, and black for the background color. And then just go ahead and click where you see me click inside of the image window, and that paints away her face. Now, if you want to confirm that the entire interior of this white silhouette is absolutely white, then go ahead and grab the Magic Wand tool, and set the Tolerance value to 0, like so, and then make sure Anti-alias is turned off, and click inside the face. In my case, I just have this little bit of chin that I need to get rid of.
So I'll press the M key in order to switch to the Rectangular Marquee tool, and then I'll Shift+drag around that little bit of animated selection outline in order to select it. And because white is my foreground color, I'll press Alt+Backspace, or Option+Delete on the Mac, in order to fill that entire area with white. Now let's press Control+D, or Command+ D on a Mac, to deselect the image. I'm going to make yet another duplicate. Now that I've gotten rid of the face, which is a fine edit, by the way, no problem so far, I'll go ahead and duplicate this most recent channel by dragging it, and dropping it onto the Page icon. And I'll rename this guy soft light painting, this time around, because Soft Light and Overlay are different Blend modes and produce different effects, as you're about to see.
Let's start things off with overlay painting. Now, this is a pretty common technique. It's gained a lot of popularity over the years, and I'll show you why. I'm going to go ahead and switch back to the Brush tool. Let's say what we want to do at this point is we want to paint that background black, because it needs to be absolutely jet black in order for this alpha channel to serve as the mask. So I'll press the X key to switch my foreground color to black, and then if I were to paint, like so, well I guess I would paint my background black, of course, but I get these big chunky lumps around my brushstroke, and I have no way of actually painting into the details here, except for being very, very careful.
Then I would have to paint around the hair. That, of course, would take me forever. So I'm going to go ahead and undo those last brushstrokes by pressing Control+Alt+Z, or Command+Option+Z, a few times in a row. And what you want to do instead: two parts. First of all, right-click inside the image window in order to bring up the Brush panel, and take the Hardness value down to 0%. I'm also going to increase the Size value to, let's say, 500 pixels for now. Now, I have been warning you against painting with a soft brush inside of an alpha channel, because after all, that does give you certain amount of wiggle room and latitude, but you also introduce all this grayness, and this softness, and these artificially feathered details as you paint.
So obviously, that's not the way to go. Press Control+Z, Command+Z on the Mac, to undo that change. Here is what you do: go to the Blend mode menu, and choose the first of the contrast modes: Overlay. What that allows you to do is preserve the opposite luminance level. So in other words, if I choose Overlay, and I paint with black, then I will darken the dark stuff, but white, the opposite luminance level, will be absolutely protected. So let's go ahead and zoom out a click here.
I'm going to increase the size of my cursor as well, by pressing the right bracket key a few times, and then I'll just go ahead and paint fairly sloppily around the right-hand side of the image, and notice what a number that does. Not only does it make that background jet black, but Photoshop also goes ahead and protects the white areas inside the silhouette. Now all I have to do is paint along the left- hand side of the image, like so, and I'm done. That's it, because again, Photoshop is protecting that opposite color.
The question is, how good of a job did it do at protecting those details? I'm going to press the M key to switch back to my Rectangular Marquee tool, just so I don't have that big, huge Brush tool on screen. I'm going to go ahead and zoom in until I get to 100%, so we can see those hair details down here on the lower right region of the model's head. Notice that they're pretty crunchy at this point. Now, it would only get worse if I were to grab my Brush tool, and click again at this location. Let's go ahead and decrease the Size of the brush by pressing the left bracket key a few times.
If I were to click and drag inside this region, notice that I get even chunkier, more jagged transitions around those hair details. I'll go ahead and press Control+Z, or Command+ Z on the Mac, so you can see the difference. So it looks a lot better before. Every application, in other words, of the Brush tool set to the Overlay Blend mode ends up further exaggerating the contrast. Now, you might figure the trick then -- I'll go ahead and switch back to the Brush tool. you might figure the trick is to reduce the Opacity value.
That actually is not the trick. That does not work very well, because what ends up happening is you take those very, very dark grays, and you make them darker, but you never quite make them black. Instead, the solution is to switch to a different Blend mode entirely, and I'm going to show you how that works, and to compare the different results, inside the next exercise.
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