RTÉ's Christmas present to viewers (apart from showing ET on Christmas Day) is high definition. The long-planned RTÉ One HD will be launched as early as next Monday, it is understood, with the channel replacing its standard-definition equivalent on the Saorview platform. It will also be added to the UPC channel line-up and become available on Sky shortly afterwards.

The launch means the most-watched television channel in Ireland is finally available in HD, which is rapidly becoming the industry norm. The broadcaster launched RTÉ Two HD in May 2011, prioritising it over its flagship channel because of the volume of sporting events on its schedule.

In October, RTÉ warned users of digital terrestrial television platform Saorview that they would have to retune their set-top boxes ahead of the switch to RTÉ One HD if they want to continue picking up the service, indicating that the HD channel would be available from the new year.

However, Christmas is a bumper period for television watching, with Christmas Day traditionally attracting the highest viewing figures of the year, while event television such as RTÉ's coverage of the New Year's Eve concert in Dublin (which it is billing as New Year's Eve Live – The Ultimate Gathering) can also provide an obvious showcase for the HD picture quality.

TV3 is broadcast in standard definition, which is much less expensive and takes up a smaller amount of bandwidth space. Although the broadcaster has access to HD filming equipment through its studio partnership deal with Sony, most of its own programmes are shot in its older standard definition studio.

TG4 HD, meanwhile, is available via UPC, and like Setanta HD, RTÉ Two HD and several other "HD" channels, most of its output is a simulcast of standard definition content upscaled to HD.

On both the UPC and Sky platforms, customers who want access to their full range of HD channels will have to pay more than the basic package cost.

There are currently five HD channels – RTÉ Two HD, TG4 HD, UTV HD, BBC One HD and BBC Two HD – available on the lowest priced UPC television offer, with a wider selection included in the package prices for UPC’s higher-functionality, higher-cost Horizon platform.

Sky sells the “HD Pack” as a specific add-on. In the UK, HD accounts for 38 per cent of BSkyB’s TV sales, but in Ireland, that percentage is thought to be lower because there have been fewer indigenous HD channels to drive package upgrades. In Ireland, that percentage is lower, due to the fewer number of indigenous HD channels here.