How To Replace Skied With Blend If
So, now we're gonna move on and talk about how we can use the different tools in Photoshop to make life a little bit easier for us when we're compositing. So, we have this house, and maybe we wanna composite clouds in 'cause makes the image look nicer, some dramatic clouds. The problem is that Photoshop has so many tools that a lot of times we forget, not that they're there, but we just have a tool that we always go to. For me, that tool is the quick selection tool, and that tool is probably not the best for this job, but this is a habit that I had to get rid of. Any time I was doing a masking job, I would instantly grab the quick selection tool, and click and drag, and although Photoshop is pretty good with the quick selection tool, this is probably not the best tool for the job. So, let me just show you what most people will do. Click and drag, and then hold Option, Alt on the PC, to unselect the areas that you don't wanna select, and then you would create a layer mask on the house b...
ased on that selection. So, click on the layer mask icon to create that layer mask. You can either, at this point, invert the selection by pressing Command + I, Control + I, on the Mac, but what I like to do instead is before creating the selection, or the layer mask, excuse me, you hold Alt, Option and it inverts the selection automatically. And then you would go in there and place the sky in. The problem is that, as you saw, I took a lot of steps, and then we would have to come in here and refine the selection using the select and mask workspace, and we would have to just keep refining this selection further and further. And although you can, at some point, get a good selection by making all these refinements, you already saw that it took me a lot of steps and the selection is not that great. So, what I'm gonna do, instead of undoing all this, to go back to the beginning, I'm gonna hold Function + F12. That is to revert the image to the last saved state. In this case, when the image was first opened. So, if you go into file, revert. I'm not seeing it, but it should be in here somewhere, but anyway, it's Function + F to revert the image to the last open state. And, what we're gonna do now is show ya how to do that same composite but just being a little bit smarter about how we use Photoshop. Photoshop creates images by using channels. The red, the green, and the blue. And you can think of these channels as masks. So, we can look at the channel that will help us for our job here. Our job is to get rid of the sky, and to place the clouds in there, so we're mainly worried about the blue here. If we look at the channels, we'll see that the blue channel has pretty much white all on the background there, and we can actually use that to our advantage to create our mask. So, I already know that I'm gonna work with the blue channel 'cause I checked them all out, and saw that the blue channel is definitely the one to use. That doesn't mean that I can't use any of the others. That just means that the blue one is the best for this particular job. There's more contrast between the objects that we wanna mask out and the objects that we wanna keep. That's essentially what we're looking for. And, if I enable the clouds layer that I wanna bring in, I can click and drag this up, and just like with anything else in compositing, you have to think about perspective. So, even with clouds, where is the ground plane? We don't see it, but we can assume that it's somewhere back here. I mean, just by looking at the image, we can tell that the ground plane's probably right below where the image was cropped. So, I know that it's gonna be somewhere down here, and now, if we look at the house, where is the ground plane? You don't have to draw lines if you don't want to, but just look at the bricks here on the driveway. You can sort of feel where the converging lines are leaning to, and you can certainly come in here and grab the line tool, and just draw lines following those converging lines, and see where they converge, and that, where they meet, that's where your ground plane meets the sky. So, the horizon line would be there. So, now that we know that the horizon line is there, let me just delete these shapes since I don't need 'em. I could also bring this layer back down, and place it right about here, so now the perspective of the clouds would match. I'm not gonna be able to show you now, but after we create the mask, I'll show you what the perspective would look like if the clouds were not in perspective. The picture of these clouds were shot just lookin' straight up, so there's no horizon line that would be visible there, or ground plane. So, we have these clouds, and we can double-click on the side of the layer here to bring up the layer style window, and notice these blend if options. We can use the luminous values of the image to reveal, or show, different parts of the layers. This layer controls the layer that you're currently on, so if I click and drag this to the right, you'll see that when pixels start disappearing, that means that anything that is this value here, or darker, will disappear, and the same thing is true for this slider. Click and drag to the left. That means that anything that is shade of gray, or brighter, will disappear. So, obviously, the white in the background. And, also, notice how there's a sharp line going around when the pixels start disappearing. If you wanna smooth that out, you can hold Option, that's Alt on the PC, split those two in half, spread 'em apart, and notice how much smoother the transition is. And then we have the underlying layer, which is the same thing, but for the layers below it. In this case, you only have one layer, but you can have multiple layers below it. And, I can click and drag this to the right. You notice how anything that's dark starts coming out, and I can push this to the left, and anything that's bright starts coming in. So, we talked about the blue channel earlier. Right now, we're working with the grays of the image, but we can also work with the channels. The blue channel is the one that had the white sky. So, if I click and drag this to the left-- Oops, I'm sorry, to the right, you'll notice that everything but the sky starts appearing, which is what we want, and at some point, we're gonna get some of that sky to disappear, which we don't want. So, we gotta go back right about here, and we can hold Option, that's Alt on the PC, split them in half, and just create a smoother transition. That way there's no harsh lines anywhere. And I can press okay. Now, the job is not perfect, but it's already much simpler and easier than what we did before. At this point, we can decide to do one of two things, or maybe even both. We can double-click on the side of the layer, and use the other channels to continue adjusting the blend. So, maybe we can use the green channel, and just click these sliders, and see if they reveal, or hide, any other areas that we wanna keep. So, in this case, if I drag this channel to the left, notice how now we start getting more of the house in there, which is what we want. So, right about here I'm gonna split this in half, so Option, Alt on the PC, splits 'em in half. It creates a smoother transition. And I can keep adjusting these blend if sliders, but at this point, I think that works. What I will do now is create what I like to call a garbage mask, which simply means creating a quick selection around the areas that I know for sure I don't want to be affected by the sky. So, notice how quickly I'm drawing the selection. It's not even very accurate. And then I'm gonna hold Option, Alt on the PC, and click on the layer mask icon to create that layer mask. So, now, everything that, any areas of the sky that should be over the house are no longer there. So, that's before and that's after, and that's much easier, and much more accurate, than going with the quick selection tool, and making those adjustments as I did before. I also talked about the perspective of the image and how it affects the house, so let me go ahead and duplicate the layer mask. I'm gonna hold Option, Alt on the PC, click and drag that layer mask up, and I'm just gonna quickly apply some of those blend if sliders to this layer, just so you could see it. There we go. It's not perfect, but the image doesn't look as good as this one, just because, again, the clouds were shot looking straight up. So, even when it comes to clouds, you have to match the perspective of these scene. I mean, like I said, that's probably the most important thing when you're dealing with compositing.