Image Processing Basics - Digital Signal Processing: Fundamentals and Applications - page 753

14.9.2 Digital Video
Digital video has become dominant over the long-standing analog method inmodern systems and devices
because it offers: high image quality; flexibility of storage, retrieval, and editing capabilities; digital
enhancement of video images; encryption; channel noise tolerance; and multimedia system applications.
Digital video formats are developed by the Consultative Committee for International Radio
(CCIR). One of the most important standards is CCIR-601, which became ITU-R-601, an international
standard for professional video applications.
In CCIR-601, chroma subsampling is carried for digital video. Each pixel is in the YCbCr color
space, where Y is the luminance, and Cb and Cr are the chrominance. Subsampling schemes include
4:4:4 (no chroma subsampling), 4:2:2, 4:1:1, and 4:2:0 as illustrated in Figure 14.51 .

720

720

480

Cr Cb ,

480 Y

444 ::

720

360

480

480 Y

Cr Cb ,

422 ::

720

360

240

Cr Cb ,

480 Y

420 ::

=Y value =Cr and Cb values =Y, Cr, and Cb values

FIGURE 14.51