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Photoshop CS4's adjustment features offer unparalleled opportunities to correct and manipulate images. In Photoshop CS4: Image Adjustments in Depth, Jan Kabili explains how to use all the major Photoshop adjustment features. She shares the best techniques for adjusting image quality, and shows how to use the new Adjustments panel to streamline a photo correction workflow. Jan also demonstrates multiple ways to eliminate color casts, and explains how to use the new On-Image Curves control to adjust brightness and color. This course offers a detailed look at the techniques photographers and designers use to master image adjustments in Photoshop. Exercise files accompany the course.
In this movie, I'm going to show you a few adjustments that aren't used very often, but are worth knowing about. And those are the Equalize adjustment, the Posterize adjustment and the Invert adjustment. The Equalize adjustment is a direct adjustment, so I don't want to do it on my Background layer, instead I'll make a copy of my Background layer by Ctrl-clicking on that layer on a Mac or Right-clicking on a PC and choosing Duplicate Layer. And I'll click OK. So the first thing, I'm going to do is to Equalize the tonal values in this photograph, and what that means is that if you look at the histogram here in the Histogram panel, you can see that most of the tones are to the left of middle gray. That's why the image looks a little flat.
A quick way to move the tones across the tonal field here is to use the Equalize command. Now there are better and more precise ways to do this as I've shown you in other movies. For example, using the Levels input sliders or using Curves. That Equalize can come in handy as a quick way to do this in some cases particularly, if you are making a kind of decorative graphic image as I'll be making here. So to apply the Equalize command, I'll just come up to the Image menu and I'll go down to Adjustments, and I'll find Equalize there at the bottom of the Adjustments menu. Taking a look at the Histogram, you can see that the midtones have now been spread out across the tonal range and there is the concentration of tones in the highlights over here, and the dark areas over here. And that's giving the image quite a bit of pop or contrast as well as more saturation in the colors.
Now, I'm going to go onto another adjustment, the Posterize adjustment. This I can add, as an adjustment layer but before I do, I'd like to isolate some of the image from this adjustment. I'd like to keep the model's face and arm with their photographic quality rather than posterizing them. So, I'm going to select everything except the face and arm. Actually, I've already done that and if you are following along, you can load that selection. By going to the Select menu and choosing Load Selection. And then in the Load Selection dialog box, go into the Channel menu and choosing selection and choosing OK. Now, I'm ready to add my Posterize adjustment layer, so I'll go to the Adjustments panel and I'm going to click the Posterize icon.
You can see the new Posterize adjustment layer down here, in the Layers panel and notice that there is some black on that layer thumbnail. I'll Option-click on the thumbnail, that's Alt-click on the PC so you can see the parts of the image that are being protected from this Posterize adjustment. I'll Option or Alt-click again on that thumbnail to go back to see the document. What Posterize does is limit the brightness levels available in each one of the color channels. If I were to take the Levels slider, and go all the way to the left where there are only 2 Levels, the only colors available would be red, blue, green, yellow, cyan, magenta, and white and black. And so the image has this real graphic quality.
As I move Levels over to the right, you can see some of the photographic quality come back. And if I go all the way over to this way, I have my plain photograph. I think, I'm going to take it back to about 4 Levels and one way to do that is just to click in the Levels field here and type 4. The next thing I'm going to do is add another kind of adjustment layer and that's an Invert adjustment layer. Before I do, I again want to load that selection to protect the model's face and arm. One way to load a selection, if it's already been used in a layer mask, is to hold down the Command key on a Mac or the Ctrl key on a PC and click on that layer mask thumbnail on the Posterize adjustment layer. And that brings back that adjustment.
Remember, everything except the model's face and arm is now selected. So when I Invert, I'll be inverting everything else in the image. I'm going to go back to the icon view of the Adjustments panel by clicking the green arrow here at the bottom of the Adjustments panel. And in the Adjustments panel icon view, I'll go up to the Invert icon right here and click it. And that adds this Invert adjustment layer. And what this layer is doing is looking at the brightness value of every pixel and inverting those brightness values. And as a result, the colors look to be the opposite of those that I saw a moment ago.
So, let me turn that layer on and off for just a moment by clicking the eye icon. As you can see, where there were yellows and oranges, there are now blues and greens. With the Invert adjustment layer selected here in the Layers panel, I'd like you to see what happens when I lower the Opacity slider. If I take Opacity all away from 100% to 0, I go back to my original view because I've re-inverted the colors. And if I put Opacity at 50% by typing it in there, actually I see none of the image because I'm right in the middle between the positive and negative brightness values for all the colors.
So that's kind of interesting, but I'm going to go back to 100% Opacity now. And I finished making this decorative image. It's not the most beautiful image in the world, but I hope that it's given you an idea of what the Equalize, the Posterize, and Invert adjustments will do for you.
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