Why response times of LCDs are misleading

[Carvahlo]

Quoted response times by manufacturers are largely meaningless and misleading.

.....because it measures the time it takes for full white to black or full black to white pixel transitions. So unless you have your monitor set to maximum brightness & contrast (so that the picture is so bright it burns your eyeballs out) and only use your monitor for flipping blank screens from white to black, and back again, whether the monitor has a 8ms response time or 100ms response time, it doesn't mean an awful lot.

It's the same reason why monitors based on the 20ms Hydis panel outperform the 12ms Samsung panel, the 16ms AU Optronics panel, the 16ms LG/Phillips panel.......

In real world use, the vast majority of monitors (over 95% of them) don't perform anywhere near the quoted response times. That's why you see streaking on the 12ms Samsung panel - its performing at 25-30ms.

Let me try and explain further.

Look at the response times for the so called 'fast' Samsung 172X which is based on a '12ms' panel:-



Since most people have their monitors set to medium brightness (about 80-180 on the grey level scale on the graph) and many applications - particularly games use grey to grey pixel transitions (or one colour to another colour) - the typical response time is somewhere between 25-30ms. Not quite 12ms is it?

Now look at the same response time graph for the Acer AL1721 - a mid level TFT with claimed 16ms response time:-



The graph is much flatter, so across brightness and contrast levels, you're going to get consistent response times. At most common user settings, the "slower" 16ms is actually faster than the "quicker" 12ms panel.

Not quite as straightforward as the manufacturers would like you to think. The problem is, by that time, most people have parted with their money. When I was first looking to buy a TFT monitor, I thought that Kustom PCs were a bit mad to stock the Acer monitors in preference to others. However, it's only on further examination that you discover they perform very very well in games - for example, the AL1731M is based on the Hydis panel - and will in fact, outperform the so called 'faster' TFT panels.

From Toms Hardware Guide:-


"For games, the Hydis 20ms panel is still the one to beat. It's not yet perfect, but we know of no other that is faster (based on our tests, of course, and not manufacturers' specifications). Once again, we must insist strongly that the manufacturers' specifications are not to be trusted. "
http://graphics.tomshardware.com/dis...26/lcd-08.html

"The response times suppliers associate with their panels vary, anywhere from 16 ms to 25 ms. The only problem is that these figures mean nothing. Or at least, not a lot. An article published in 2001 that can be viewed at Xtremtech explains the situation pretty well, and we have summarized it for you in the section entitled "RT between colors". But this isn't the only problem..."
http://graphics.tomshardware.com/dis...ny_old_stuff_i
http://graphics.tomshardware.com/dis...05/lcd-05.html

[Tumble]

That's very interesting... Thanks matey

[Apex]

aye, been reading much of the gfx stuff on tomshardware and thats why i decided not to get a 12ms pannel

[turkster]

Hmm interesting

I've got a Iiyama Prolite E431s, supposedly 16ms, dunno how well that performs in those tests although it seems nice enough in use

[Apex]

it uses 16.2m colours to get it's 16ms time...which is cheating tbh

[Butuz]

Excellent post. Its kinda akin to the whole "why one gfx card has better img quality in 2d than another argument" its not down to pure specs, its how your eyes interpret parts of those specs and some are just better in the important specs than others

Butuz

[MAS]

it uses 16.2m colours to get it's 16ms time...which is cheating tbh

Can you just explain this? I was aware of the whole reducing colours to get a lower response time. But I recently bought a Samsung 193P. It's amazingly nice; the colours are awesome; but apparently it's only 16.2m colours, which is annoying, because the response time is only 20ms - it's not like it's even 16ms.

So how much difference does it make between 16.2m and 16.7m colours? You'd think that another 500k colours wouldnt make much difference, but obviously it's not that simple. I think 16.7m colours is 24 bit. Does that make 16.2m 16 bit?

I'm not that bothered about specs; the monitor looks fantastic to my eyes and that's the main thing. I'm just curious.

[directhex]

16 bit is 65,536 colors.
24 bit is 16,777,216 colors.
it ain't 23 bit, since that's 8,388,608

so buggered if i know

[MAS]

So basically it's just marginally not quite as good?

[MuTTy_Hc]

very interesting post mate, bravo.