Masking a subject against a green screen

- [Instructor] In this movie, I'll show you how…to mask an image set against a green screen.…And in the process, we'll take this image,…once again from the Dreamstime image library,…and we'll immerse it inside this chaotic environment…of what I'm calling swirling variables.…Alright, so let's take a look at a few formulas here.…For starters, when you're shooting against a green screen…or a blue screen for that matter, you want to light…the screen as evenly as possible.…And you want to set the lights typically between…the foreground subject and the green screen…so that the subject of your photograph…is not casting any shadows.…

Now in our case we have a less than ideal effect…because the background is brightening up…to form a kind of gradient.…So if you light your scene properly,…if anything, you'll get better results.…Alright, so let's take a look at a couple of formulas…that you apply using the calculations command.…First of all, if you have a green screen,…then for reasons I'll explain in a moment,…you set Source one to the red channel,…