Which term is used to describe a method that allows the compression of video data by reducing color information?

Chroma Subsampling is the term used to describe the method that allows the compression of video data by reducing color information. This technique exploits the human visual system's lower sensitivity to color detail compared to brightness detail. By sampling the color information at a lower resolution than the brightness information, Chroma Subsampling effectively reduces the amount of data required to represent the image.

This is commonly implemented in video formats to decrease file sizes while maintaining visual fidelity. For example, in a typical 4:2:0 sampling scheme, the color information is sampled at half the resolution of the brightness information in both horizontal and vertical directions. This allows for significant data reduction without a noticeable loss in picture quality for the average viewer.

The other terms mentioned are related to video processing but serve different purposes. Color keying and chroma keying are techniques used in video production to create transparent backgrounds based on specific color ranges, often for compositing purposes. Pixel compression refers to reducing the file size of an image or video without specifically focusing on color information. Therefore, Chroma Subsampling is the most accurate term for the described method of compressing video data through color information reduction.