geir ove rapp’s weblog

Traditionally EBU and ITU has recommended a viewing distance of between 4 to 6 times screen height for standard definition television and down to 3H for high definition. BBC has taken it further and performed a survey on the relationship between resolution, screen size and viewing distance. If you sit 2.7 meters from the TV screen, which is average viewing distance in Europe, then you want a pixel size of 0.8 mm. By this logic you should be content with the standard definition 576 lines up to screen diagonal sizes of 37″, 720 lines up to 45″ and 1080 lines up to 70″.

This means that Full HD 1080 has no effect on a 42″ if you sit more than 2.5 meters from your TV screen. I have a 42″ Panasonic and my viewing distance is about 3.3 meters, which implies I don’t need HD at all, or turned the other way around, I should have at least a 55″ to be able to enjoy Full HD 1080 :-) Can someone please tell my wife?

I must however argue that I can clearly see a difference viewing the same material in standard definition 576i and 720p. It should also be noted that the tests performed by BBC are all using progressive scanned source material, even for standard definition. And progressive scanned material does in any case outperform interlaced scanned material, hence my observation (see EBU B/TQE; High Definition for Europe – a progressive approach).