How To Match Luminance And Saturation
When you're working in Photoshop, in compositing specifically, you have to think of saturation and the luminance of the background and foreground and they have to match, of course, so the image looks realistic. And the first thing that I'm gonna show you is how to match luminance which is, essentially, matching atmospheric perspective. But in this case there's not that much atmosphere. I mean, there is a background and it recedes, but not as much so in your mind it might not be atmosphere perspective, so I'm calling this section matching luminance. Although, technically, it is very similar. And if I create a black and white adjustment layer, you'll notice right off the bat why she doesn't fit as good in the scene, because she's so much brighter than the background. And if we create a, this time we'll use a curves adjustment layer, a curves adjustment layer and then use the keyboard shortcut to click that layer, to layer below it, option command G, we can adjust the brightness of the im...
age to match the background. Just by doing that, she fits much better into the background. So that's matching luminance. Now the thing that may be a little bit harder to do and especially visualize is matching saturation. And to match saturation, let me first create a hue in saturation adjustment layer and notice that when I created it, since I created it in between the previous curves adjustment layer, it automatically clipped it to the layer below it. So it's clipped to the model layer. So I can increase her saturation and decrease her saturation. So how will we match the saturation of our model to the background? Of course, you can eyeball it but again a lot of times when you're eyeballing it, you really don't know what you're doing so what I like to do is I like to create something called a saturation map. It essentially turns the image black and white and the saturated areas are bright and the de-saturated areas are dark. So the way you would do that is by creating a selective color adjustment layer. And you would have to go in through all the colors, so red through magenta. Under the absolute value, radio button excuse me, and just bring the blacks down to negative 100 on all the colors. And then once you get to the whites, neutrals, and blacks, you increase the blacks all the way to positive 100. I'm not gonna do that now just cause I already a preset called saturation map, which is included for free for the people who purchase a course. It's a preset that simply adjusts these values for you and you can load it by going into Load selective color preset and that preset will be there for you anytime you need it. So, but that's essentially how I create it by going into all those colors and bringing it back down to negative and whites, neutrals, and blacks positive 100. Having a preset just saves you a whole lot of time. So, this turns the image black and white. And what this saturation map is telling us is where are the saturated areas of the image so we can match them. So if I enable this hue and saturation layer again, and I make adjustments. So I'm gonna increase the saturation, notice that she gets brighter. If I disable the saturation map, and I'll name the saturation map just so you know what that is. Saturation map. So there's the saturation map there. Obviously she oversaturated. If we bring the saturation down to zero, she's black and white. And she's black on the saturation map. So that's what the saturation map allows you to do. It allows you to visually see how much saturation there is in an image, and then you can match it sort of like we match luminosity by making sure that the, that it looks good in black and white. So I can come back in hue and saturation and I can just adjust it and what I'm really doing here is looking at her skin tones and maybe trying to match those grays to the grays that are nearest here to us so maybe somewhere around there and if I disable the saturation map, you'll see that she fits a little bit better in the image. There's more saturation in the background and the foreground and if you're still unhappy with it, you can of course increase the saturation even more and come back and check it with the saturation map.