YUV Video Format

What is YUV video format? YUV video format is a color space typically used as part of a color image pipeline. It encodes a color image or video taking human perception into account, allowing reduced bandwidth for chrominance components, thereby typically enabling transmission errors or compression artifacts to be more efficiently masked by the human perception than using a direct RGB-representation. Other color spaces have similar properties, and the main reason to implement or investigate properties of Y'UV would be for interfacing with analog or digital television or photographic equipment that conforms to certain Y'UV standards.

Maybe you'll be interested in: convert YUV to videos.

The scope of the terms Y'UV, YUV, YCbCr, YPbPr, etc., is sometimes ambiguous and overlapping. Historically, the terms YUV and Y'UV were used for a specific analog encoding of color information in television systems, while YCbCr was used for digital encoding of color information suited for video and still-image compression and transmission such as MPEG and JPEG. Today, the term YUV video format is commonly used in the computer industry to describe file-formats that are encoded using YCbCr.

The Y'UV model defines a color space in terms of one luma (Y') and two chrominance (UV) components. The Y'UV color model is used in the NTSC, PAL, and SECAM composite color video standards. Previous black-and-white systems used only luma (Y') information. Color information (U and V) was added separately via a sub-carrier so that a black-and-white receiver would still be able to receive and display a color picture transmission in the receiver's native black-and-white format.

The primary advantage of YUV video format is that it remains compatible with black and white analog television. The Y signal is essentially the same signal that would be broadcast from a normal black and white camera (with some subtle changes), and the U and V signals can simply be ignored. When used in a color setting the subtraction process is reversed, resulting in the original RGB color space.

Another advantage is that the signal in YUV video format can be easily manipulated to deliberately discard some information in order to reduce bandwidth. The human eye actually has fairly low color resolution, the high-resolution color images we see actually being processed by the visual system by combining the high-resolution black and white image with the low-resolution color image. Using this information to their advantage, standards such as NTSC reduce the amount of signal in the U and V considerably, leaving the eye to recombine them. For instance, NTSC saves only 11% of the original blue and 30% of the original red, throwing out the rest. Since the green is already encoded in the Y signal, the resulting U and V signals are substantially smaller than they would otherwise be if the original RGB or YUV signals were sent. This filtering out of the blue and red signals is trivial to accomplish once the signal is in YUV video file formats.