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In the previous chapter we talked about Levels and in this chapter we are going to get into Curves. Now a lot of times what you will hear people say and rightly so, they will say that you know with Curves, you can do everything that you can do with Levels but more. Or you can think of Curves as Levels on steroids. Now that been said, does that make Curves better than Levels? Well, not necessarily because Levels are relatively simple and easy to use and there's times when you want to reach for a tool like that. Yet here is my guess. My guess is that you are going to spend a majority of your time in Curves, once you learn how to use them properly. So let's go ahead and spend a few minute deconstructing the Curves dialog window and how Curves actually work, so that we can begin to use this amazing Adjustment tool on our images.
All right, well for starters here, we have the Curves dialog. Let's talk a little bit about this. We have the ability to choose a preset, to choose a channel, either a composite view or a Red, Green or Blue channel. Here is the curve itself. If I drag this up, the image is brighter; if I drag this down the image becomes darker. Now that's true with the RGB Composite mode. Next we have some more display options we can choose here. We have Eyedroppers so we can sample areas of our image and then color correct or change the tone of our images. And we have a few other options as well on the right-hand side. But so far we have covered the essentials.
Well let's then get into these different channels. Now one thing that's actually pretty significant, a big change inside of CS4, is the shortcuts for the different channels. Now I'm not going to talk about the old shortcuts because that will get confusing but now on a Mac you press Option+2 for the composite, and then 3 for Red, 4 for Green, 5 for Blue. On a PC that's the Alt key. So keep in mind when you are working with Curves, it's now Options or Alt+2, 3 or 5, okay great. Well, let's then take a look at the Red channel. Now how do we begin to understand the Red channel, well here we can see it; we actually have to think of this as the Red-Cyan channel. And if I click and drag this curve up towards the word Red which is right here, the image will become more red. If I click and drag away from that, if I remove red the image will become more cyan.
The next channel we have is the Green channel, think of this one as a Green-Magenta. Again clicking towards the name of the channel adds Green, clicking away removes green or adds magenta. And then our final channel is the Blue or the Blue-Yellow channel. So we want to start to think about that relationship because if we can begin to understand that will help us out. Well here I have this color wheel and I'll go ahead and target that and open up a Curves Adjustment layer and with this Curves Adjustment layer I'm going to click and drag up, that will brighten everything. You will also notice that the colors are less saturated, click and drag down, it will darken everything and now the colors are more saturated. So I can click on a point in the curve and then drag that one way or the other.
Now when you make an adjustment in Curves, let say an adjustment like this and it doesn't look good and you want to reset the Curves adjustment. Well, hold down the Option key on a Mac/Alt key on a PC that changes Cancel to Reset, that's a great shortcuts to know. So I'll go ahead and Option-click that because I'm on the Mac/ that will be Alt-click on a PC. Now let's choose another channel here. I'll go to the Red channel, now here I'm in the Red channel and I'm going to click and drag up, now the overall color wheel becomes much more red. Click and drag down, what does it become? Much more cyan, interesting.
Now let's say I want to remove a point, we will click and drag it off to the side. Now let's go to our next channel. Do you remember the next shortcut? On a Mac that's Option+4, on a PC that's Alt+4. Again, click and drag up becomes more green, click and drag down more magenta, click to drag that point off. Final Channel we are going to select is the Blue channel and here we can control the overall blue, just cool it off or warm that up. All right, we will cancel out of that. What I want to do now is look at how this will actually affect an image. So here I have an image, I'll open up my Curves dialog window.
The shortcut to open up the dialog is Command+M on a Mac or Ctrl+N on a PC. And the reason why I want to open that up here is because I want to begin to see how my Curves adjustments will affect in actual image. Well, I'm going to go ahead and brighten it or darken it, okay kind of interesting, but not very good. I do have a Preset which might help me out and that is a Preset to increase the contrast. So I'm going to go ahead and choose that option, interesting. Now my before and after, well I see that I'm in the beginning of what's called an S curve and this is a real elementary curve which can help us add a little bit of contrast.
We can create our own S curve this way, hold down the Option key on the Mac, Alt key on a PC and then click Reset. Now here I'll click and drag up my whites, click and drag down my blacks, just making my blacks blacker, my whites whiter. Now all that I'm doing here is the equivalent of using Levels to bring in my two points. Click Cancel here for a moment and open up Levels. Again the equivalent of what I just did was bringing in my whites and my blacks to increase the contrast and color saturation, okay.
We talked about this composite view mode, how about the Red channel. Well, here we are going to see an increased amount of red or an increased amount of cyan, okay, interesting. Let's go then to the Green channel, now we see the green and then the magenta, great. And then finally the Blue-Yellow channel, the blue and then the yellow. Then I'll click to drag it that point off. Now keep in mind that as you begin to modify your images, sometimes what you will do is work on the Red channel, add some red to the image. And then go into the Blue-Yellow channel, here you are going to add a little bit of yellow. And then you are going to go to the Green- Magenta channel and you are going to add a little bit of green. Now you have a very different overall color mix based on this. Here is our before and after, is it better? Well, not necessarily. Yeah, what I'm trying to illustrate is how you begin to work with these Channels together.
To exaggerate this even further, let's go ahead and choose Cross Process. Now this will give me this cross processed effect. Let's look at the different channels. Well, here is my RGB composite view mode and there I can see that this channel hasn't changed very much, but the red line is showing me how the Red channel was affected, the blue line, the Blue channel and the green line, the Green channel. Now if I go to the Curve Display Options, I can turn off that view by clicking on Show, Channel Overlays and now just look at one channel the time and here you can see what happened to my reds, my greens and my blues. Now I'll go back to the RGB composite channel and then I can still modify the overall intensity of that adjustment. So as you can see you can make some real drastic adjustments to your images and mostly what I want to point out here is that you can make adjustment in the different channels. It's those channels working together that will equal the final results.
Now you may be thinking, okay gosh, that's a little bit strange. Yet most importantly, what I want you to walk away with from this chapter is that your Red channel is actually red-cyan, your Green channel is green-magenta and that your Blue Channel is actually the blue-yellow channel. All right, well now that we know quite a bit about Curves, let's go ahead and step back for a moment and begin to apply some of the more simple things that we know to some of our images.
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