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In this exercise, we're going to see yet another way to use this Grayscale command right there to extract a black and white image from a full color photograph, but this time as opposed to extracting that black and white image from an RGB photograph, we're going to take advantage of an alternate color model known as Lab. Now, I've gone ahead and saved our progress so far. First, there is this image called Grayscale composite.jpg, which is the grayscale fusion of all three of those color channels into one.
The next image is called Blue to gray.jpg, and that's that Blue Channel from the RGB image, we just went ahead and abandoned the Red and Green Channels in order to get this effect here. And then we also have our original Agrarian gothic.jpg file. And what I'm going to do here is switch to the original color image and then go up to Arrange icon and click on Consolidate All, or if you loaded dekeKeys, you've got a keyboard shortcut, Ctrl+Shift+A, Command+Shift+A on the Mac. Let's go ahead and scroll this image over that so that we can see more of it at a time, and notice that we do have an RGB image, with independent Red, Green, and Blue Channels.
And the reason I mention this is because, this is an extremely popular color model for very good reasons. First of all, it's a color model that's employed by your digital camera, it's the color model that's employed by your scanner, it's used by your computer monitor and your TV set and your overhead projector and everything that either captures or projects color. So basically the one big exception is a printer, and whenever you're putting ink on a page, then you're using CMYK or some other mix of inks or pigments, something along those lines.
But then in addition to RGB and CMYK, we have yet another color model. This one is device independent, that is to say, it's not subject to the interpretation of a digital camera or a scanner or a computer screen or a printer or any of that stuff, and it's designed to emulate the way that we perceive colors, but it's going to seem awfully foreign at first. So I want you to watch the Channels panel right here, we've got an RGB composite that contains a Red version of the image, a Green version, and a Blue version, and in any point in time, you can actually mix these together.
If I click on Red and then also eyeball Green right there, I'll see a combination of the Red and Green Channels working as one here inside the Image window. So we've got everything but the Blue information. So we've got our Greens, we've got our Reds, we've got our Yellows, which are a combination of Green and Red working together, to get the full color image, we add Blue, and that will become useful information in just a moment. I'm going to go up here to the Image menu, choose mode, and choose Lab Color, and that's going to convert our RGB image into a Lab image.
Some folks call it LAB; totally up to you how you decide to work, but A and B don't stand for anything. L stands for Lightness, which is the luminance information inside the image. So notice we still have three channels of information working together. This is the luminance information or Lightness, if you prefer, and then A and B are arbitrary letter designations for both the tint information inside the image; I know it doesn't look like anything so far, just be patient for a moment.
This is tint information inside the image and this here B is the temperature information. So temperature is more of an important topic than tint, so let's take a look at B and Lightness together. As soon as I turn on this Lightness Channel by clicking on its eyeball, things begin to make a little more sense. So instead of seeing this nebulous gray information inside the B Channel, we now see that nebulous gray represented as color, and we can see that we've got our yellows, all the way through our blues.
So think of that big color wheel that we saw way back in the Fundamentals portion of the series and imagine a slice going right through it from yellow to blue, which are complementary colors, as you may recall. This is what the B Channel is able to convey, is basically that slice of information, so we can see the warm information inside the image, which is going to be the skin tones, and we can see the cool information, the blues, which are showing up in basically the synthetic materials. So the earring in the Goth girl here and we've got the jacket in the figure in the background.
Let's now go ahead and turn off B for a moment and turn on A. Now, A is a perpendicular slice through that same color wheel, and this time this tint information is representing essentially the pinks. We don't have a real color, people say it's the greens to the magentas, but that's not strictly speaking true. It's more of the pinks inside of the image, all the way through the turquoise colors. So just think of a perpendicular slice of complementary colors, and then together when you add them both up, if you go ahead and click on B again, then you get that full color image.
Now, you can also choose to look at just the color independently of the Lightness if you want to, it's not going to make a lot of sense, but then we're seeing all of the colors inside the image independently of the luminance levels. And the reason everything looks this murky gray is because gray is the default luminance level where A and B are concerned when they're mixing together. So all we're missing here is the whites and the blacks to go along with it and then we end up having a recognizable image like this. All right! So where does this factor into creating a grayscale image? Well, what you can do is you can click on Lightness, and this is the way a lot of folks advocate that you create grayscale images, I don't necessarily advocate it, it's just yet another way to work.
Some folks say this is the purest way there is, because this is the real luminance data, man. I say, just another option. Anyway, click on Lightness to make it active. You might want to go ahead and turn off the other two channels as well, so that you can see what it is you're getting. And then you go up to the Image menu, choose mode, and you choose Grayscale, and once again Photoshop is going to say, do you want to discard the other channels? Do you want to get rid of A and B? And your answer is OK. After all of this, if you get sufficiently familiar with things, you can say don't show again. I'm not going to do that though, I'll just click OK.
Now, there is that Grayscale version of the image, and now let's go ahead and view all of these images together by clicking on the 3 Up range icon, and our images have been rearranged, because Photoshop's very fond of doing that, but let's go ahead and tab away all of the panels in the toolbox and the Options bar and everything else, and let's see if I can go ahead and get these images arranged into alignment. I'm Spacebar dragging this left-hand image here and then I'm adding the Shift key once I get that guy aligned, so that I'm moving everybody together.
So what we're seeing here, in the middle we're seeing the Grayscale composite, that's a fusion of the Red, Green, and Blue Channels. Over here on the right-hand side, we're seeing the Blue Channel by itself; we could have just as easily chosen the Green Channel or the Red Channel by itself as well. And then over here on the far left side, we have that luminance information that was extracted from the Lab image, and it ends up being the lightest of the bunch. It wouldn't necessarily if we were comparing it to the Red Channel. So you never know how it's going to shake out. But these are three very easy ways to capture a Grayscale image inside of Photoshop.
But then there is the option of mixing your own custom black and white image using one of two commands, either the Channel Mixer or the Black and White command, and we'll see how those functions work, beginning in the next exercise.
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