Chroma key is one of the most popular digital video editing effects.

Using chroma key, you can make virtually ANYTHING happen in your digital video.

Want your video to take place on the other side of the universe? Chroma key is the video editing technique that can take you there in seconds, for nothing.

Chroma key is commonly called green screen. Most people are familiar with the term green screen. That’s where your on-camera talent stands in front of a bright lime green background. Then, through editing, all the lime green is removed from the shot and another image is inserted in its place.

This young boy is ready to be transported to the other side of the universe using green screen effect.

Green screen is the common term, but technically, chroma key is more accurate. Chroma key can use any color, not just green. All it takes is the right equipment to handle the different colors. That flexibility can make life much easier.  This video below relies heavily on chroma key effect.

In this recent internet viral video I made poking fun of the presidential election, I used chroma key for several things.

Add eyes and nose to the alien character, Fonda Lots-a-Titty
Blow up the inflatable Barbie doll
Have the bank robber trample John McCain.

(Have you seen this video? It’s really impossible to explain. You just gotta SEE IT.)

Here’s how chroma key helped me make that video.

First, to make the alien character, I made some “eyeballs” out of tennis balls, wire, paper and pipe cleaners. It was much like a kindergarten art project!

We video taped the eyeballs bouncing on the wire in front of a red cloth background. I shot the left eyeball and the right separately, so I could get as close as possible and fill up the frame. This helps your final chroma key effect look best. Then we yanked out the eyelashes out and shot it a third time as a nose.

In order to make your final chroma key effect look right, you have to shoot it with VERY BRIGHT, DIFFUSED LIGHT. You do not want shadows when shooting something for chroma key. Shadows in the back ground alter the color of your background by making it darker or lighter in spots. To do an effective chroma key, you have to have a VERY CONSISTENT COLOR for your background. Remember, this is the color that will be digitally removed. Any slight variations in the color will affect how well you can remove it and replace it with another image.

I used red as a chroma key background for the eyeballs and nose because the tennis balls were a greenish-yellow color. To get a better chroma key, I needed to use a color opposite of the color of the tennis balls. Lime green is most often used for chroma key effect because it is opposite on the color spectrum from facial tones. Because it is opposite, the digital removal of one color won’t affect the other. This would be why you never see a weathercaster wearing a lime green dress.

I used a red background for the Barbie doll shot too because Barbie was wearing a green dress. That ended up being a mistake. Barbie’s skin tones blended in with the red too well. 

When I got my video shots in the video editing software, (I use Final Cut on a Mac Pro) I put the jpeg of the alien’s head and torso on line one of my timeline. I put the right eye, left eye and the nose shots on lines two, three and four. Each shot is separate because that gives me more control over placement, size and other details.

I applied the color key filter to each eyeball and the nose shot. The filter is not needed on the jpeg of the alien.

The color key filter in Final Cut lets you do chroma key using any color. So I matched the color to the red background I’d taped. I then played with details of the filter, including the tolerance level, the edge thickness and the edge softness. By adjusting these levels individually I got the chroma key effect to look as good as possible. Sometimes it wasn’t necessarily very good, but with the eyeballs, I made that work to my advantage.

Like I said earlier, in order to get all the background color out, you have to shoot it with very bright diffused light and get a shadow less shot. I’m not able to do that very well because I have real limited lighting equipment. Plus, the best red background I could scrounge up was a crinkled red dress. (I work with what I have; this is low budget video folks. No Hollywood expense accounts here.)

I scotch taped the dress to the wall in order to get some of the wrinkles out, but that only helped a little. Combine that with my bad lighting and the red background was not very even so it was hard to get out. Plus, the eyelashes and the wire were both skinny to begin with. Large objects chroma key more easily.

In order to turn bad video into art, I put the edge thickness and edge softness of the chroma key filter up high. This gave the eyeballs and eyelashes a soft red glow. I thought it looked cool.

On the shot of the Barbie doll though, the problems were so bad that I abandoned the use of chroma key filter There was no way I could get the red out without taking lots of Barbie’s face with it. Her arms really disappeared badly too. So did the letter opener we used to prick her in the tush. So, enter Plan B.

I just cut out the majority of the red background using a matt instead. That basically crops it out and is a completely different effect from chroma key.

I let Barbie have a huge red background and just didn’t worry about it.

A matt is also how I added the lips. That was not chroma key, just the nose and eyeballs were. I shot the lips close up and then cut out as much as possible using an 8-point garbage matt. That lets me set 8 different points where the shot gets cropped. Then I added the shot of the lips onto the top line of the timeline in order to complete the face.

In addition to doing a red chroma key for this video, I also used a white chroma key. Look at the opening with the space ship. The spaceship was a jpeg on a white background. I chroma keyed it over a star background I generated in Live Type. (Life Type is a program that comes bundled with Final Cut and you can do easy title animation and backgrounds.) Most of the white disappeared easily, but I left a faint white soft glow around the edges because I liked it.

The bank robber was also a jpeg and his background was beige. So I used the chroma key filter and set the color to beige. Then I key framed the bank robber to run over a shot of John McCain.

So, there you have it. How chroma key technique helped me make my goofy internet viral video.

Thanks for reading Video Production Tips

The Internet Video Gal

Lorraine Grula