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In this movie, I'll show you how to use the Channel Mixer to create a kind of infrared black and white photography effect. I'm once again looking at the original full color photograph, which comes to us by the way from the Fotolia image library. About, which you can learn more at fotolia.com/deke. And lets start things off by reviewing the channels once again. I'm going to switch over to the Channels panel. And what I want you to notice are the freckles on the young woman's face. So, in the Red channel they're there, but they're the least visible. In the Green channel they start to show up more.
And then they're extremely prevalent in the Blue channel. Well, imagine we were to invert the Blue channel so that her skin tones were actually darker than the freckles. And we were to apply that inversion to the Green and Red channels. And that's what we're going to do by effectively subtracting Blue from Red and Green. So, here's how it works. I'll switch to the RGB image and switch back to the Layers panel, then press the Alt+Option key. Click on the Black/White icon at the bottom of the panel and choose Channel Mixer.
And I'm going to call this layer Infrared B and W and then click OK. And now here inside the Properties panel, because we want to create a black and white image, turn on the Monochrome check box. And for a moment I'm just going to 0 these values out so that we have no luminance contribution from any of the channels as a result. We've got a total of 0% luminance, which means I just turned the image entirely black. Now, I'm going to crank the red value up to 100% so we're seeing the red channel by itself.
And I'll also crank the green value up to 100%, which means we now have 200% luminance, which is of course over-brightening the image. To compensate I'm going to subtract 100% Blue and we end up with a total of 100% once again. Now, you can see at this point we've pretty much removed all of her freckles especially in the highlight regions of her cheeks. But I'd like to go further still. So, I'm going to take that blue value down, let's say, to negative 150.
And when your just experimenting with Channel Mixer, this is the way you work, you take one value down, another value up and so forth. And I'll compensate by taking the Green value up to say 150%, so we're back to a total of 100%. Which Photoshop will tell you is okay because it's not showing a warning. But the histogram is going to tell you it's not okay at all. Because if I update that histogram you can see that I have a ton of highlights that are clipping to white. And that's not what I want. So, I'm going to try to resolve that issue by reducing the Blue value even further.
So, I'm taking it down to negative 170%. Notice that I am clipping some shadow detail to black over here on the far left side of the histogram. And anytime you're trying to address the shadows with Channel mixer, you want to go down to this constant value. And so I'm going to raise the constant value to 2% and that reduces the amount of clipping in the shadow details. But now, I have some gaps over here on the right hand side of the histogram. Meaning that I need to add to the highlights. So, I'm going to take this Green value up to ultimately 153 and then you can see, when I update the histogram, that it's quite nicely balanced.
Problem is we are starting to get some posterization. So, if you zoom in on the woman in the background, you can see that we have these patches of differently shaded gray. And so we've got some pretty rapid luminescence transmissions going on. A kind of continuous tone stair-stepping. And we have the same thing at work up here in the skies. Now, I could mitigate some of that by backing off of the these values here so that they're not so very far apart, the Blue value's not this negative. And the Red and Green values aren't this positive, but I like the effect.
So, I don't really want to get rid of it, I just want to figure out a way to downplay this posterization. So, I'm going to hide the Properties panel and I'm going to convert the background into a smart object and then apply a little bit of Gaussian Blur. So, I'll click on a background to make it active, then with my rectangular Marquee tool, I'll right-click inside the Image window and choose Convert to Smart Object. And I'll go ahead and rename this smart object photo, or something like that. Then I'll go up to the Filter menu and choose Blur and choose Gaussian Blur.
And I figured out that a radius of four pixels is about the lowest value that smooths away those transitions there. So, we still have something resembling posterization but at least we don't have sharp, jagged edges. And I'll click OK in order to apply the effect. The obvious problem is that in addition to blurring the woman in the background who was already out of focus I've blurred the woman in the foreground, which is not acceptable at all. So, I need to apply a mask to my Gaussian Blur filter and I'll do that by clicking in this white Filter mask.
And then I'll select my Gradient tool, which you can also get by pressing the G key. You want to make sure that your gradient goes from black to white. And then drag from this region, between the young woman's eye and the bridge of her nose. And while pressing the Shift key, you want to release right about here, at the point where the young woman's hair ends. And now we'll go ahead and reveal her, so she's no longer blurred, while leaving the blur in the areas that have posterization. Now, that ends up blurring the tip of her nose a little bit, which, of course, (LAUGH) doesn't look realistic at all.
So, I'm going to switch to the Brush tool, which you can get by pressing the B key. And then I'll right-click inside the Image window. The size value of 125 pixels is going to work fine. But I'm going to take the hardness value up to 50% and press the Enter key or the Return key on a Mac in order to accept that change. Make sure that the foreground color is black. And then go ahead and brush in the nose and down the mouth and the chin, like so. And you can brush in her face a little bit, although it's already in the black region.
And than you might also want to brush across that left eye and up into the forward hair like that, toward the top of her head. And that way it looks like this small area of hair over here on the left hand side is beyond the focal range. And now let's compare what we've got here. This is the effect we achieved just by choosing the greyscale command. This is the effect we got in the previous movie by mixing our own custom black and white image. And then this is the infrared effect created by subtracting in this case the Blue channel from the Red and Green.
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