PALplus-the European system for wide-screen terrestrial TV

PALplus enables a fully backwards compatible terrestrial PAL transmission of 16:9 programs. It uses a letterbox for format compatibility with a vertical helper transmitted in the black bars that enables the new receiver to restore the full vertical resolution. A cooperative processing for improved Y/C separation is used that switches between colour plus and adaptive comb-filter according to the type of source material. Signalling information is transmitted in the first half of line 23 that configures the PALplus decoder for optimum performance. PALplus can be introduced step by step on a program by program basis. The signalling information can be introduced immediately and enables the next generation of 16:9 receivers to automatically switch the aspect ratio of the display according to the transmission