YCbCrväriavaruus

YCbCr is a color space that represents color information as a luminance component (Y) and two chrominance components (Cb and Cr). This representation is commonly used in video transmission and storage, particularly in digital television systems and image compression. The Y component carries the brightness information of the image, while Cb and Cr carry the color difference information. Cb represents the difference between the blue component and a reference luminance, and Cr represents the difference between the red component and the same reference luminance.

The YCbCr color space is derived from the RGB color space. The conversion involves a linear transformation of the R, G, and B values to obtain Y, Cb, and Cr. This conversion is advantageous because the human eye is more sensitive to luminance than to chrominance. Therefore, the Cb and Cr components can be sampled at a lower resolution than the Y component without a significant perceived loss of image quality. This process is known as chroma subsampling and is a key technique in video compression standards like JPEG and MPEG.

Common chroma subsampling schemes include 4:4:4, 4:2:2, and 4:2:0. In 4:4:4, all three components (Y, Cb, and Cr) are sampled at full resolution. In 4:2:2, the horizontal resolution of Cb and Cr is halved, while the vertical resolution remains full. In 4:2:0, both the horizontal and vertical resolutions of Cb and Cr are halved. The choice of subsampling scheme depends on the desired balance between image quality and file size or bandwidth requirements. YCbCr is widely adopted due to its efficiency in representing and compressing color information for visual media.