### Is Full HD really necessary?

As well as asking BBC staff how far they sat from their TV sets, the researchers ran a second set of tests to determine how much detail the human eye can resolve. This was done with a series of test images, and methodology that’s described in some detail in the whitepaper.

Essentially, it involved comparisons between series of filtered and unfiltered images, and the result was broadly in line with the accepted figure of one minute of arc - 1.054, to be precise.

In fact, the BBC research wasn’t strictly concerned with viewing distance, but with what quality of image needed to be broadcast, based on the ability of the eye to discern detail, at the median viewing distance of 2.7m (8.9ft). And the results are quite surprising:

Spotting the Detail
Picture resolution vs screen size

Plot resolution (vertical axis) against screen size and, at an average distance of 2.7m, viewers can't see the difference between 1080p and 720p for the most common TVs
Source: BBC

For the vast majority of viewers, a resolution of 1280 x 720 - 720p - will be sufficient for screen sizes of up to 50 inches diagonal, while 1440 x 1080 may suffice 50-56in screens – a figure that may perhaps influence the decision to broadcast some BBC HD services with a horizontal resolution of 1440 rather than 1920 pixels, though it's also to do with maintaining a 4:3 aspect ratio - which contains an anamorphic picture that stretched to the correct dimensions by a widescreen telly.

And if you’re one of those who feels that you’re being short-changed by the picture quality on some channels, or perhaps someone who simply can’t see what all the fuss is about, a second set of results shows the proportion of people in the test who required a specific standard.

At sizes of 35-40in, it seems that up to around 15 per cent per cent of people will notice a higher quality than 720p, though the proportion noticing anything better than 1440 x 1080 doesn’t increase beyond 15 per cent until screen sizes exceed 45in.

Next page: The maths bit

### You've got it all wrong....

There are two criteria for choosing a TV size....depending on where you live.

1) It must be bigger than the people who live in the council house next door.

2) It must cost slightly more than what you can afford.

Simples.

Now, being serious (did you realise I wasn't being serious above?), were the tests done with very high bitrate images (I may have missed that in the article)? the main problem I have is the crappy blockiness caused by low bitrate FV channels, although it does seem to have improved since the switchover, but that might be wishful thinking. Unless all the videos were pushed passed the point of blockiness these test would be, like a blunt pencil, pointless.

### Obvious stuff

I could have told the researchers that HD on a 32" set was pointless, since to my (reasonably good) eyes this looks no better than normal PAL on a 28" set. Of course, Americans have been putting up with lower-resolution NTSC on mahoosive TVs for years, so there is more of an upgrade imperative there.

HD is only necessary due to the relentless increase in screen size. When you get to 40" and above PAL really doesn't cut it, and 40" is a smallish TV by new standards.

Anyway, we still have a 28" CRT in our living room. The quality of programming is sufficiently bad that we don't feel the need to upgrade. You can't polish a dog's egg.

### Wow

You want people who support decimalisation to pack up & leave? TBH I couldn't give a fig what standard of measurement we use here. I just wish we could make our damn minds up and make a bloody decision.

32", so I'm one of those underendowed watchers. But if I'm playing COD, my nose will be right up to it. If, on the other hand, the wife is watching Desperate Housewives my viewing distance becomes exponentially and progressively larger as the tedium unfolds.

### @Robert Long 1

Actually, we have two sets of 8 fingers with an extra pair to serve as "carry" and "sign" flags. We should be measuring everything in Hexadecimal--the only number system designed for humans.

-dZ.

### Simple but effective. Top Tips (not Viz).

Don't laugh but I do have a solution for people when choosing a screen size. Simply get some large pieces of cardboard with 16:9 ratios of a number of common screen sizes. Then plonk them in the corner of your room or above the mantlepiece, sit back and see if they're the right size for the room.

It may seem silly but it has stopped people I know from buying behemoths that would swallow their living rooms or postage stamps that would give them eye strain.

No, no need to pay me but you could buy me a pint.

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