This refers to HDTV signals in RGB form rather than Y,Cr,Cb form. The difference is that HD RGB is a 4:4:4 signal that can carry the full bandwidth of each of the R, G and B channels, whereas HD (TV) is normally considered to be in 4:2:2 form where the color difference signals have a more restricted bandwidth. Generally, the 4:2:2 form of HD is sufficient for most television applications and can be carried in its uncompressed form by a single SDI connection. HD RGB is often used for critical keying shots for television, and for digital cinematography. The availability of a suitable recorder makes working with the format generally more affordable.