Green mat technology in movies
Green mat technology also commonly known as chroma keying is widely used in film shooting. Chroma keying is nothing but picking up a color and replacing with a different image using computer graphics. In simple terms, the sequence is shot in the studio using a particular color background and later the background is changed as needed using CGI. Any of the primary colors or secondary colors can be used as the background. But the colors should not match your skin tone. Blue and Green are the widely used colors. Blue screen has less brightness and hence green screens are mostly preferred. basic idea is to have a better-lighted background.
While shooting if the costume and background are of the same color the lighting effect will be reduced. The dark color in the background and light color costumes makes the background bright. But not always light color costume can be used. Therefore when dark color costumes are used except green the background color is made green. During the shoot, the background will be green so as to make the surroundings brighter. The background is later changed using computer graphics.
Green/blue screens are based on the idea of chroma keying. A specific color is chosen and replaced with different color or background. Blue screens are used in place of green screens because it is generally easier to chroma key and the color is softer than green. But due to some specific reasons, the green color is commonly used. The main reason being the high luminance and reflection properties of green color making the background bright. The green color is also used since a blue background may match a subjects eye color or clothing such as jeans.
This technique has been used heavily in many fields to remove a background from a photo or video. It is mainly used by the newscasting, motion pictures, video game industries and in video production and post-production. It is commonly used for weather forecast broadcasts where we see the reporter is seen standing in front of a large map, but it is actually standing in front of a blue screen. It is easier to display the map on a blue background. If the news reader wears blue clothes, his/her clothes will also be replaced with the background video. It is also common in the entertainment industry for visual effects in movies.
Chroma keying can be done using any color to make a person invisible. If the background and the persons clothing are same, it may seem as if the person has disappeared. Thus this technique is used for creating an invisible effect. Chroma keying is very helpful when there is a lack of budget to shoot at different locations.
Just like any other technique this technique also has disadvantages. One of the major disadvantages of chroma keying is color spill/green spill. It occurs when the color reflects off the back screen and casts a noticeable change on the subject. The light bounces off the green screen and hence the color is shown on the subject. Because of the color spill, the subject may look artificial. In order to avoid it, the color spill must be removed and make it look natural. It is done using computer graphics. The primate chroma key plugin gives many ways to remove color spill by maintaining the smallest details. Thus chroma keying / green mat technology is a great boon in the entertainment industry.
Green mat technology in movies