50Hz 100Hz 200Hz....

soulandy

So just what does all the Hz thing mean? Does getting a new telly with 100Hz mean that it will be a better picture than one with 50Hz? is it to do with screen size, the bigger the better, or does it relate to HD viewing? Will a 100Hz be far better than a 50Hz when watching HD content.or is it just a marketing ploy!! We have a panosonic 32" screen with full HD with 100Hz. Dosent seem a great deal better than the old 28" crt that packed up. We have no HD boxes, just the telly with freeview.
Cheers

Bikertov

Hz (an abbreviation of Hertz) is the measurement of Frequency, in cycles per second.

You often see it when you talk about mains electricity - in the UK electricity is 50Hz (50 cycles per second) wheras in America electricity is 60Hz.

When talking about TV's, it is in relation to the screen refreshing rate. 100Hz and 200Hz means the picture updates more quickly. This has the effect that for fast moving films and sport there is less blur.

spaceboy

Yeah it's the refresh rate, 100Hz means 100 times per second.

Interestingly my parents have just got a 100Hz LCD TV with Freesat HD and there only seems to be one HD channel (BBC HD) and it's broadcast at 25Hz...

aliEnRIK

With respect to tvs its generally meaningless.
English broadcasts and dvds etc are at 50Hz, blurays at 24Hz and NTSC (American) 60Hz
So the best conversion you can get is making 50Hz into 100 or 200 or whatever. HOWEVER, many tvs with a '100 Hz' mode tends to look no better than its 50Hz mode and in some cases even worse due to its poor processing.
So to sum up, dont read ANYTHING into the Hz range when buying a tv. (Unless you want a really surreal effect as a lot of modern tvs have some form of 'motion processing', which never looks right)

spaceboy

There's an LG which is apparently 600Hz.

aliEnRIK

spaceboy wrote: »

There's an LG which is apparently 600Hz.

Theres a couple of tvs with 600Hz. But its nothing to do with motion its to do with colours (And its very technical to explain). And the LG does it badly and looks worse than a standard 100Hz tv!

spaceboy

aliEnRIK wrote: »

Theres a couple of tvs with 600Hz. But its nothing to do with motion its to do with colours (And its very technical to explain). And the LG does it badly and looks worse than a standard 100Hz tv!

I like technical explanations please go into more detail.

Btw NTSC is actually 30fps (or 29.97 to be more exact). And UK are 24fps (or 23.98).

4743hudsonj

well its just guessing what should be in the 11 other 'frames'(i know its not this but for simplicity) between actual 'frames' should be

most human eyes cant even process the difference, some even get aggetated, mine one of those. i can now just about bear 100hz for an hour but no longer without migraines

4743hudsonj

spaceboy wrote: »

I like technical explanations please go into more detail.

Btw NTSC is actually 30fps (or 29.97 to be more exact). And UK are 24fps (or 23.98).

hz and fps are different

fps is merely the number of images per second displayed, so the smoothness of the image

hz is the refresh rate of the image ang how sharp it is simplistically(ish) lol not too easy to convey over a forum

aliEnRIK

Pedantic much?

So whats 3-2 and 2-2 cadence exactly?

Ive copied this direct from another guy ~

This is indeed pure marketing, they needed a large number - they've got it. That this number does not mean anything - doesn't matter, nobody cares. And indeed - we see that everyone is confused now.


Ok, here is how it works:


Plasma screen can indeed only have it's pixels on or off. There is no half-on or something like this.


So, how are different shades being generated?


The answer is simple - for every field, ANY plasma is using a number of subfields. In earlier days e.g. 300 subfields, which made 5 subfields per field (60Hz operation mode).


So, how is the 'luminance' being genearted out of those subfields?


This is done by differnt algorithms, every manufacturer is using their own. Common thing between them is - it is using a modified pulse-width-modulation. Modified, becaue a plasma cell can only be activated once during the sequence of one field.


Assuming 600 Subfields and 100Hz feed, we have 6 Subfields per field.


So, what are valid subfield sequences for e.g. a green sub-pixel?


1-0-1-0-1-0 is not a valid sequence - since, as I mentioned, a cell can be only activated once.


0-0-1-1-1-0 is a valid sequence. Here the cell is activated once at a subfield #3 and is being de-activated at a subfiled #6


How exactly this activatinon/deactivation is being implemented with every panel, e.g. in the middle of the subfiled sequence, at beginning or dynamically, is intellectual property of manufacturers and is not being disclosed.


There are a number of patents existing on this subject matter. The sequence of the subfield activation is important for a level of artifacts like False Contouring or flicker with plasma screens.


As such, number of subfields (e.g. 600) doesn't tell anything. The only important thing is - how many subfields per field are being used.


For example 480 Subfields, but with a 60Hz refresh, is better (8 subfields per field) than 600 Subfields at 100Hz (only 6 subfields per field).


So please just try to ignore those irritating numbers born in the depths of the marketing department, they do not have anything to do with how the picture or movement look like on the screen.

-Alex

spaceboy

ok so is ther actually any advantage of a 100Hz refresh rate over a 50Hz rate?