| 摘要 |
<p>In a letterbox-type video signal, in which a main signal is sent on the lines forming the central three-quarters of the picture, additional helper information is transmitted in the upper and lower borders of the picture. This helper information includes chrominance components that provide enhanced horizontal detail, for vertical frequency components up to a small proportion of the vertical detail carried in the main signal. At the encoder the chrominance components are vertically sub-sampled (16) to produce one line from every six input lines, and are horizontally stretched (18) and split (20) so that each input line extends onto two lines. At the decoder the operations are reversed by retiming onto one line and horizontal compression (42) and vertical super-sampling or interpolation (44). The extra chrominance detail can then be added (46) to the main signal chrominance components to enhance the horizontal detail.</p> |
