Inserting a background in a video can be achieved through a process known as chroma keying, which involves replacing a specific color in the video with another image or video. The color that is replaced is often green or blue, hence the term "green screen" or "blue screen." The use of a green screen is not a necessity for every video, but it does make the process of chroma keying easier and more efficient.
In the absence of a green screen, other methods can be employed to separate the subject from the background. These methods include the use of lighting, color correction, and matte extraction. However, these methods can be more time-consuming and less effective compared to using a green screen.
Using a green screen has several advantages. Firstly, it provides a consistent and uniform background that can be easily replaced, making it ideal for special effects and compositing. Secondly, it minimizes the need for color correction and matte extraction, which can be a time-consuming process. Lastly, it eliminates the need to reshoot a scene, as the green screen can be replaced with a new background in post-production.
However, there are some disadvantages to using a green screen. Firstly, it can be expensive to purchase a high-quality green screen, especially for small-scale video production. Secondly, the lighting conditions need to be carefully controlled to ensure that the green screen does not cast shadows or reflections on the subject. Thirdly, the subject must be separated from the green screen, which can be a difficult task when dealing with hair, clothing, or transparent objects.
In conclusion, the use of a green screen is not a requirement for inserting a background in a video. While it can make the process easier and more efficient, other methods can be employed in its absence. The choice of whether or not to use a green screen depends on the specific requirements of each video production. As a source, the website "Video Production Tips" states that "The use of a green screen is an important tool for video production, but it is not a requirement for every production."