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Enhancing the channel's contrast


show more Enhancing the channel's contrast provides you with in-depth training on Design. Taught by Deke McClelland as part of the Photoshop CS3 One-on-One: Beyond the Basics show less
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Enhancing the channel's contrast

Our next task is to enhance the contrast of this channel right here, this My Mask channel, that's a duplicate of the red channels, you may recall it from the previous exercise. We need to enhance the contrast so that her hair and face are totally white against a totally black background with a little softness, a few gray values in between. In other words, we are trying to get to this mask channel right there to that final mask. Alright, so I am going to go ahead and click on My Mask which as I said is the channel that I created by duplicating the red channel.

And I am going to enhance the contrast for starters using the Levels command just because it's the simplest approach to the problem, you could also use the Curves command if you want to. I am going to up to the Image menu, I am going to choose Adjustments and I am going to use the Levels command. And I am going to go ahead and raise the black value and lower the white value. Let's start by lowering this white value, so we are going to drag this white slider bar over to the left, until we get to somewhere in the neighborhood of 120 let's say, which means that I am saying that anything that has a luminance level of 120 or lighter is now going to become white inside of the image.

So that means I am blowing a ton of highlights. If you take yourself back to our levels' discussion several chapters ago, you might say golly, Deke, you are taking all of these colors right here, this world of luminance levels inside the image and you are making them white. Well, that's okay in the context of a mask. You want to turn a lot of colors white. You want to turn everything that's inside of this woman and inside of her hair white against a pitch-black background. Now, speaking of the pitch-black background is pretty weird that the background has a bunch of sort of dim noise in it now because we have elevated the colors, we've made those shadow lighter until we get to this point right here where it's solid black, all of a sudden it just cuts off.

And I imagine that the photographer went ahead and extended the canvas a little bit to include some black over here on the left-hand side, that's perfectly fine, it's something we are going to deal with right now, we just need to make sure that this entire area is a homogenous black. And I am going to do that by raising the black value, I am going to drag the black slider triangle over to the right until this first value right here is 20. So I am saying anything that has a luminance level of 20 or darker is going to turn black inside the image.

And that's what we've done, and we definitely have a higher contrast effect as a result. So, once again, 20 for black, 120 for white, don't worry about the gamma value in the middle here, just leave that alone and then go ahead and click OK in order to accept the modification. So, just so you can see what kind of difference that command made. This is before the before version of this specific channel and this is after. So we are a heck of a lot of closer to our destination right here, which is this, however, we still have some room to go. Now, I do want you to see on other thing.

I am going to zoom in here a little bit. Notice that we are seeing a fair amount of noise inside of the gray area, that's left over here inside of this channel. But we are not getting nearly as much noise as we got from the Color Range command. This is the noise that was produced by Color Range. This is the noise that is produce by working directly from the red channel. So let's go and zoom out here so that we can see the differences right too. This is the Color Range selection and this is the work we've done so far with the red channel.

They are similar in many regards here. That big difference is that the Color Range produces a much rougher selection, a much rougher mask. If we can, we better off working directly from the channel information. Alright, so there we have it. We did a lot of work just using that Levels command and we are going to do a lot more work, we're going to fix these guys right here, we're going to lighten them up so we get a nice bright mask using the Dodge tool beginning when, in the next exercise.

Enhancing the channel's contrast
Video duration: 4m 3s 10h 47m Intermediate

Viewers:

Enhancing the channel's contrast provides you with in-depth training on Design. Taught by Deke McClelland as part of the Photoshop CS3 One-on-One: Beyond the Basics

Subjects:
Design Photography
Software:
Photoshop
Author:
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