Green Matte in Chroma Key

Sep, 2017

If you had seen the shooting of any VFX footage, you are sure to know about the matte used in the background. Nowadays, it is mostly of green color. But why it is green is the question? May be, digitization calls for it! Here’s more on this.

Until digitization or we can say until the use of the Chroma Key technique, VFX Artists has experimented and even produced movies using mattes of black color and yellow color. They had proved to be useful for the needs of those times.


Primary Reason for the Emergence of Green Matte

The key criterion for selecting the color of the matte is to eliminate or reduce the noise and grain, while the matte color is removed from the scene. So, the artists always experimented on colors that are far in the spectrum from the colors of human skin tone and the properties used on screen. This was the first reason that gave way to blue and green color mattes, as these colors are far from human skin tones. And green took a higher hand when it worked well for outdoor shots, as blue screen matched up with the sky.


More Highs for Green Matte

·         Green color registers brighter on electronic displays, avoiding noise.

·         It was cheaper to light than blue.

·         Green Mattes are bright enough, letting you to use lesser number of studio lights and thus saving money. 

·         The color is less common in costumes than blue.

·         Modernised cameras are more sensitive to green.

·         Digital sensors of today use a Bayer Pattern, which has a higher number of green photosites to capture luminance, making the cameras more sensitive to the green part of the spectrum.



Remember these when you use a Green Matte

·         Light your scene evenly to avoid color bleeding onto the subject and to avoid shadows.

·         Ensure there are no wrinkles in your backdrop.

·         Ensure that your subject does not wear green color costume, accessories or any property. This is a key point with any other matte color as well. Ensure that your subject does not have the same color as that of the matte used.

·         Ensure you leave enough space between the subject and the matte, to avoid any spillover.


Other Mattes in the Digital Era

While green matte is popularly used, blue is also a commonly used one depending on the color to be used in the subject. That is, if the subject is to dress up in green or to have a green color property, then the blue matte is used. But when you use a blue matte, ensure that you have two times more light.

It is also noteworthy that there are some cases like underwater type setup, where a green or blue color matte may not work out. In such cases, digital red matte is used. If you happen to use a digital red matte, ensure that there is no human skin exposed.



Whatsoever color matte you want to use, it is best to experiment a lot with them and select the best suitable one for each shot.