Home Entertainment & Technology Resource

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

What is 100Hz for? Seems to spoil all TV's Pics?

Discussion in 'TVs' started by ABP, Jul 9, 2001.

  1. ABP

    ABP Guest

    Ratings:
    +0
    Been to see 32" TV's. All of the 100Hz Models,Panasonic, Toshiba et al,seem to suffer from smearing to some extent. Also Horizontal moving text(Seen like a ticker on Sky Active) looks very poor.These 100Hz 'No Flicker' sets still do flicker! The 50Hz Sets dont seem to suffer from any of these problems.Is this a case of The Emperors New Clothes or am I missing something? :confused:
  2. LV426

    LV426 Administrator

    Joined:
    Jul 14, 2000
    Messages:
    11,840
    Trophy Points:
    166
    Ratings:
    +3,154
    100hz processing has the following MAIN effect:

    The rate at which the picture on the screen is re-drawn is doubled from the normal 50x per second to 100x per second.

    As with all things, it has unwanted side-effects such as you describe.

    There is a proportion of the population (I am one) who are sensitive to low screen refresh rates and, the larger and brighter the image is, the worse it is. The crappy PC screen I'm looking at now is refreshing at 60hz and it's flickering noticeably. I find this very straining and uncomfortable.

    Therefore, if I were buying a large TV right now I would insist on 100hz because, the faster the refresh rate, the less visible it is. And I would live with the other problems - I'd find them more tolerable than 50hz flickering.

    However, the majority of people don't see flicker and are more upset by the other problems.

    At the end of the day, if you are buying, you buy what suits you, not me.

    What's frustrating about all of this is that many, many years ago, Sony made a 29 inch 100hz TV (the first, I think) which did NOT suffer from any of the problems that modern 100hz TVs do. It was very expensive (£2k I think).

    Which probably answers the question; newer TVs are probably built down to a price, rather than up to a standard.

    FWIW, I'm looking forward to cost-effective LCD TVs (LG have promised a 20 inch 16x9 set this year for about £1200) because these don't have ANY visible flicker and I find these MUCH easier on my eye.
  3. Piglet

    Piglet Guest

    Ratings:
    +0
    LCD tv? is it like a moniter kind of television? what worries me about that is, its new technology right? so wont it just be like the first plasma televisions, and the first 100hz televisions and be really poor and overpriced for what your getting?

    explain what it means. im prepared to buy one as im bloody sick to death of flickering and smearing. ive wasted so much money now that i just want a tv i can settle with.
  4. LV426

    LV426 Administrator

    Joined:
    Jul 14, 2000
    Messages:
    11,840
    Trophy Points:
    166
    Ratings:
    +3,154
    LCD TVs are TV sets in which the picture is produced using and LCD flat panel, of the same basic principle as are used in Laptop Computers.

    Sharp, Samsung and LG are the main players. Sharp are very expensive. Can't speak for Samsung. Preliminary evidence is that LG are going to be cheaper, although there is a "worrying" article on this website this morning about a 22inch LG at over £3k. Oh dear.

    Although LCD technology has been around in Laptop PCs for some years now (and might therefore be assumed to be a mature technology) the addition of a TV tuner is relatively new. And there are very few TVs available. But it's a fair bet that more are coming......

    Right now, you can go to selected Dixons, Currys, Comet (and possibly others) and see the first LG set on display. It is a 15inch 4:3 set with Nicam, Text, etc., and retails at £900. This will give you an idea about how LCD TV looks. Oh, and it can also be used as a PC monitor. According to WV&TV, LG promise a 20inch 16:9 item later this year for £1200.

    As I said before, it's going to be necessary to wait for this emerging market to settle down before buying - unless you have cash to spare.
  5. ISCM

    ISCM Guest

    Ratings:
    +0
    The smearing that you get on 100HZ TV's is caused by digital artifacts (The set hat to do digital encoding and decoding in realtime). If the TV's had faster and better processors it may then not be so much of a problem.
    It seems to me that the manufactuers needed a selling point that would be cheap to implement and released technology that was not ready.
    I think that the original Sony 29" 100HZ was not digital, but I may be wrong. :rolleyes:
  6. loz

    loz Active Member

    Joined:
    Jun 4, 2001
    Messages:
    12,290
    Trophy Points:
    133
    Ratings:
    +1,407
    I find on my Philips 36" the artefacts depend on the source.
    The more artefacts in the source, the more you get from 100hz processing, as the two are adding together.
    I find
    Non on analog
    Almost non on DVD
    Some on the premium Sky channels
    More on the cheap, low bandwidth Sky channels
    the 100hz is magnifying the problems already in the stream.

    Having said that, on the philips the only problem this manifests itself as is blockeness around objects fast moving across the screen usually where there is high contrast.
    (which is why you get it with the ticker tape text as you mention - though usually is stabalises itself - but this makes for a juddering effect)

    I still find it preferable to the 50hz flicker which for me was always very noticable
  7. hudson806

    hudson806 Guest

    Ratings:
    +0
    Many of the problems described here are caused by the fact that TVs made by the likes of Panasonic, Sony and Philips have almost no ability to de-interlace the interlaced signal they are fed (interlacing is the process of displaying all the odd lines on the screen, followed by all the even lines.) These lines need to be recombined for display on 100Hz sets, causing shimmering on edges and 'combing' in high contrast areas.

    The good news is that there are decent 100Hz TVs out there, with high quality deinterlacing, if you look hard enough. Unfortunately, they're made by companies like Loewe and Metz, are hard to find and are expensive.

    The other thing to remember is that the contrast tends to be waaay to high on sets in showrooms, and 100Hz tends to look much worse than 50Hz when the contrast is up high. So even if it looks rotten in the showroom, it may not look so bad in your home...
  8. delta

    delta New Member

    Joined:
    Oct 16, 2000
    Messages:
    469
    Trophy Points:
    0
    Ratings:
    +0
    The Toshiba range are excellent on 100Hz
  9. geekbeek

    geekbeek Guest

    Ratings:
    +0
    I know this is going to sound primitive & stupid to you folks, but, I have recently purchased a 100 HZ Phillips 29" TV & i do find the pic quality to be amazing. I did not like the LCDs because of their poor response time.:)
  10. Stephen Neal

    Stephen Neal Active Member

    Joined:
    Mar 29, 2003
    Messages:
    6,080
    Trophy Points:
    133
    Ratings:
    +703
    100Hz processing, as others have mentioned, was designed to reduce the "large area flicker" that 50Hz refresh-rates displays can be seen to suffer from. Large area flicker is usually more noticable in peripheral vision than in the central area, so it becomes more of a problem with larger screens.

    Some people are more sensitive to it than others, and US/Japanese viewers used to 60Hz refresh rate displays are much more sensitive to it - at least initially.

    By doubling the screen refresh rate to 100Hz the flicker is massively reduced - and becomes invisible to almost everyone at TV viewing distances, phosphor decays and brightnesses. (CRT flicker on a PC monitor at 60Hz is more noticable because PC monitors are often much closer to you than a TV, and thus occupy more of your field of view - and thus more peripheral vision, and often have brighter pictures - as most PC displays are based on bright backgrounds these days - which flicker more than black obviously!)

    However converting 50Hz interlaced material to 100Hz interlaced material (100Hz displays still use interlacing - they aren't progressive) is actually pretty difficult to do cleanly. You can't just repeat every 50Hz field twice, and neither can you simply repeat each 25Hz frame, as with fluid motion you'd be jumping forward and back in time and get awful judder.

    Instead 100Hz displays have to convert an analogue signal to digital, do a form of de-interlacing from 50i to 50p, frame double to 100p and then interlace to 100i, (there are other ways of converting 50i to 100i but they aren't great) and convert back to analogue for display, which as everyone involved in HD knows is almost impossible to do totally cleanly, and very difficult to do at a low cost consumer price point. The early 100Hz displays used very poor A/D and D/A (often only 6 bit) conversions, and very low sampling rates (much lower than the 13.5MHz used for pro gear) giving very soft results, but at the time the costs of high quality A/D and D/A conversion and frame storage and high speed processing was prohibitive. Added to this is that any noise (and compression artefacts appear to be noise in some cases) present in the source will confuse a de-interlacer, and thus relatively high levels of noise reduction were added, causing smearing, and if the noise reduction is removed often the motion processing falls over.

    Additionally, some manufacturers have added motion interpolation algorithms, which if switched in will convert 25p originated film material to a 50i/p look "video" motion - making films look like they were shot on interlaced video cameras!

    I've yet to see a 100Hz CRT I would chose to watch full time - and of course broadcasters would never use them for picture monitoring in critical situations (as the picture is hugely altered by the processing) They have got better in recent years at the high end - but the artefacts are still clearly visible.
  11. baseline

    baseline Guest

    Ratings:
    +0
    I still use my 25" Trinitron ( 50 hz ) as my main set.

    Later 100hz Trinitrons, suffered from motion artefacts, as described already.

    the beauty with 50hz, is that its a natural refresh, based on mains AC 240v 50hz.

    HAving said that , to quality CRT monitors, at 100hz, dont suffer from the same artefacts, they are much higher resolution tubes, and the electronics are more sophisticated. a large 21" pro CRT monitor, originally cost far more than the largest 100hz CRT TV ( at the time )

    I dont find 50hz a problem, sure its not 100% rock stable, but at the same time, its not a problem either. and the superb image is unbeatable.

    poor old CRT, no one had a problem with 50hz sets, until the manufactures decided to produce 100hz, as a gimmick, to make people buy a new set

    same goes for the flat tvs, under reason to buy a new set.

    always gimmicks. at no point have ANY of the manufacturers ever stated, that the newer sets HAD A BETTER IMAGE than the older one !! more gimmicks, flatter, YES

    but better image ? not stated anwyhere !!!
  12. baseline

    baseline Guest

    Ratings:
    +0
    Excellent tech explanation, much appreciated ! :smashin:

    thats a huge amount of processing, just to try to reduce flicker, which was not really a problem ( was it ? )

    Also, CRT monitors suffer more at low refresh rates, as you stated, due to closeness of viewing, but also, due to the fact we are read tiny text on WHITE background. refresh is only really noticeable on bright areas.

    If I had to use a 50hz CRT TV as a monitor, then it clearly would be unsuitable. :suicide:
  13. aekostas

    aekostas Member

    Joined:
    Jan 2, 2006
    Messages:
    1,236
    Trophy Points:
    48
    Ratings:
    +60
    Copying from http://www.avforums.com/forums/showpost.php?p=2430915&postcount=30

    In other words, as the size of the screen increased to accommodate 16:9, flicker became a problem and 100Hz was introduced to address it.
  14. baseline

    baseline Guest

    Ratings:
    +0
    28" widescreen, just 1" taller than a 21" 4:3

    this says it all. why would anyone bother to get a 16:9 CRT ? but millions of people did.

    for 95% of tv programs, there is no advantage to widescreen.

    a nice 29" 4:3 would really have a much larger image, than even a 36" widescreen.
  15. aekostas

    aekostas Member

    Joined:
    Jan 2, 2006
    Messages:
    1,236
    Trophy Points:
    48
    Ratings:
    +60
    I can tell you why I bought a widescreen TV: because nothing else was available. I can tell you why you may need a 16:9 TV: I saw the (weak) reason when I tried to watch the LOTR DVD (2.35:1) on my 21" 4:3. Small does not begin to describe it.

    Now, where did I last hear that last one?

    Nevermind...
  16. fallenangle

    fallenangle Member

    Joined:
    Oct 19, 2005
    Messages:
    404
    Trophy Points:
    21
    Ratings:
    +24
    Come on, I don't know about the EU and other countries but in the UK very little TV is broadcast in 4:3. Films (because so many people have widescreen TVs) are now usually shown in their original panoramic cinema format. Digital TV, like Freeview, is mostly presented either in true 16:9 widescreen or various letterbox formats well suited to a widescreen TVs aspect ratio.

    But my point is that although some TV is still best viewed/presented in classic 4:3 most isn't so that I can't see any reason now for not getting a widescreen TV, at least if you're going for a 28" one or bigger. IMO whether you're using it for broadcast A or D TV/DVDs/games, unless you're go for a <28" 4:3 TV, it will suit most of your needs better.

    As to the 100Hz issue I think the jury is out.
  17. geekbeek

    geekbeek Guest

    Ratings:
    +0
    The specs on my 100HZ Philips is as follows

    Supported Display Resolution
    Video formats : 480p, 60Hz, 720p, 50, 60Hz, 1080i, 60Hz, 1080p, 60Hz

    Why isn't there a 100HZ Display resolution ? I am totally confused here:( .
    could someone help please ?
  18. aekostas

    aekostas Member

    Joined:
    Jan 2, 2006
    Messages:
    1,236
    Trophy Points:
    48
    Ratings:
    +60
    Can you get us the model number?
  19. geekbeek

    geekbeek Guest

    Ratings:
    +0
  20. Seb71

    Seb71 Member

    Joined:
    Feb 27, 2007
    Messages:
    22
    Trophy Points:
    3
    Ratings:
    +7
    Those are the input video formats that your TV supports (the formats that it can accept as inputs and then display). If it is a 100Hz TV, it will display any of this sources at 100Hz refresh rate. But it is strange that 576i 50Hz and 576p 50 Hz are missing on a PAL TV.
  21. oldnewbie

    oldnewbie Member

    Joined:
    Feb 13, 2006
    Messages:
    1,076
    Trophy Points:
    63
    Ratings:
    +181
    The beginning of the thread really brought a smile to my face, a cheap 20inch lg lcd for £1200:eek: , just shows you how prices have changed in just a few years,:rotfl: just as well:smashin:
  22. aekostas

    aekostas Member

    Joined:
    Jan 2, 2006
    Messages:
    1,236
    Trophy Points:
    48
    Ratings:
    +60
    I found another spec sheet that says that the set does "PAL I" and still misses 576p/i.

    http://www.p4c.philips.com/files/2/29pt8836_94/29pt8836_94_pss_aen.pdf

    EDIT: Looks like a cracking TV, btw.
  23. geekbeek

    geekbeek Guest

    Ratings:
    +0
    Thanks Seb71.

    Thanks aekostas.

    So the supported display resolutions given are actually the input video formats that the TV can accept, right ? i thought they were the display resolutions that this tv is capable of.

    The down thing in this TV though is the audio. It sounds too bad. You've got to connect it to your HT. :)
  24. Mofoman

    Mofoman Member

    Joined:
    Feb 6, 2007
    Messages:
    167
    Trophy Points:
    28
    Ratings:
    +40
    100hz is largely dependent on the source material, if the source material is crap, then the picture will pixelate and smear, as it will show up badly after being processed, but if the material is good, then the difference between it aand a good 50hz is a bit of a double edged sword, on the one hand, you have an overly bright picture which flicker's alot, and on the other yyou have an overly soft image which doesn't flicker. I would say that 50hz is better, but 60 is my preference . I still do not mind 100hz as it is a crt image with outstanding colour reproduction and when the source material is good is has that wow factor you get with good crt.

    Obviously it is a consumer product as for broadcasting, it is far too imprecise. But for some people who are very sensitive to flicker, such as epeleptic's and migraine sufferer's, the technology has proved very useful.

    The trouble for me lie's with the pal technology and I suppose this is a preference thing, I just hate 50hz, I prefer 60hz as the gain of lines is pretty negligble for the low resolution material of TV broadcast anyway.
  25. geekbeek

    geekbeek Guest

    Ratings:
    +0
    In these days of DTH & component & HD inputs, the 100HZ TV is really useful.
  26. jay2

    jay2 Member

    Joined:
    Sep 4, 2009
    Messages:
    118
    Trophy Points:
    18
    Ratings:
    +4
    Hey all, I'm looking at getting a 100HZ tv, I just wanted to know how much 100HZ has improved?

    BWT. I found this thread doing a Google search about 100HZ.
  27. clemenzina

    clemenzina Member

    Joined:
    Jun 25, 2006
    Messages:
    1,540
    Trophy Points:
    66
    Ratings:
    +142
    I just caught this thread and my mind was boggling at the conjecture about LCD and prices... then I noticed that the year of the early posts was 2001 :rolleyes:

    clemenzina

Share This Page