Video Compositing or Bluescreening Video at Home Can Be Easy

It became popular back in the late 80s for shows about how they make movies to show how bluescreen techniques work. If you took the NBC tour at the Rockefeller Center, one of the first things they delighted in showing you was how when a weather person on the weather report stands in front of the animated weather graphic and waves his hands around, he's actually standing in front of a plain blue screen and simply guessing at where everything is. The technical word for that is video compositing. Today we have expert video production company explaining the finer points of ths amazing technology.

Why do they call it “video compositing” and not simply “bluescreening” or something obvious like that? The bluescreening technique is actually meant to blend two images, one on top of the other – the weatherman shown on top of the graphic for instance. That's what compositing is.

Remember looking at those The Making Of shows feeling awestruck? Well, personal computers are so advanced now that you could easily and cheaply do that right at home. All you need is an average computer and software like Adobe Premiere.

The reason you need to stand in front of a bluescreen to do any video compositing is, it gives the computer a simple and straightforward way of knowing which parts of the frame to replace with something else.  Use blue or green or a nice bright color, and the computer will be able to crop very closely around the picture of you to replace with whatever background you have in mind. Just as long as nothing on your clothing is the exact same shade of blue or green, it'll be fine.

In principle, it's very simple. You take a picture of something – say a walk around Disneyland – and then you take a short video of you walking in front of a bluescreen. The software will look at your blue screen video and cut your shape out of it, frame by frame. It will then cut your shape out of the Disneyland video at the exact same spots frame by frame, and replace you with it. It's as simple as that.

Building a bluescreen or greens clean at home is simple enough. It'll probably not cost you more than $100. You just need to buy a few bright sheets of plastic at a home improvement store. Tablecloths that are the right color would be great. Barring that, you could just paint a wall completely blue or green in the right shade. Just be sure to use something that's non-glossy. It shouldn't be reflective at all.

Once we have the bluescreen ready, make sure that it's very well lit. Aim several reflector-equipped lights at it, and it should be fine. Those should soften the light and make sure that it spreads evenly.
Once you’ve shot your subject in front of the screen and you have the video of the background that you wish to composite into it, doing the job of the computer is simple enough. In Adobe Premiere, you just need to choose the transparency settings, find the chroma function, click on some portion of the video with blue in it so that it'll know what shade you're talking about, and then hit Okay. That's about it.

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