Channel 4 to launch HDTV service
Channel 4 is to be broadcast in high definition later this year, the first time a UK terrestrial broadcaster has simulcast its output in this way.
Viewers with a compatible TV and Sky HD box will be able to watch Channel 4 HD without paying an extra subscription.
However, only programmes recorded using high-definition techniques will be screened in HD, a format which promises better-quality pictures and sound.
Other shows will be seen in standard definition, a Channel 4 spokesman said.
He added that the proportion of programmes shown in HD would increase over time.
The BBC has offered a trial HD service since last year, but this free service carries a customised selection of programmes, rather than simulcasting an existing service.
Channel 4 said it "anticipated" that its HD service would launch in December.