The process of changing a video background without the use of a green screen is commonly referred to as "chroma key compositing." This technique involves isolating a specific color in the video and replacing it with another image or video.
One method for achieving this effect is to use a chroma key software. These programs are designed to remove the green or blue background from a video and replace it with a new image or video. Some popular chroma key software options include Adobe After Effects, Final Cut Pro, and Nuke.
To change the background of a video using chroma key software, the following steps can be followed:
Import the video into the software: The first step is to import the video into the chroma key software. This is typically done by selecting the "import" or "open" option in the software and then selecting the video file from your computer.
Isolate the background color: The next step is to isolate the background color. This is typically done by using the chroma key tool in the software to select the color that you want to remove. In most cases, the green or blue background is used as it provides the most contrast with skin tones and other colors in the video.
Add the new background: Once the background color has been isolated, you can then add the new background by selecting an image or video file from your computer. The new background will replace the original background in the video.
Adjust the transparency: Depending on the chroma key software you are using, you may need to adjust the transparency of the new background to ensure that it blends seamlessly with the foreground elements in the video.
Render the final video: Once you have made any necessary adjustments, you can then render the final video by selecting the "render" or "export" option in the software.
It is important to note that the quality of the final video will depend on several factors, including the quality of the original video, the chroma key software used, and the skill of the person using the software.
Source: "Chroma key compositing" (Wikipedia)
In conclusion, chroma key compositing is a valuable technique for changing the background of a video without the use of a green screen. By using a chroma key software, it is possible to isolate the background color, add a new background, and render a final video with a completely different background.