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Pros and Cons of ALIS Panels

Discussion in 'Plasma TVs' started by chrise, Jun 8, 2003.

  1. chrise

    chrise
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    I am puzzled by the amount of critical comments about ALIS panels as made by Hitachi/Fujitsu. Are they based on facts or just bias?

    ALIS panels have received rave reviews in HCC, What Video etc. won awards etc. I bought a Hitachi based on comparative viewing but many of the local gurus on this forum and more particularly on the American AVS forum dismiss ALIS completely -why?

    Reasons I have seen is noise from fans but not all ALIS screens have fans, & noisy power supplies but this seem to apply equally to the Panasonics according to other posts and seem down to luck or sensitivity. Few talk about picture quality.

    According to the specs the screen resolution of 1024 by 1024 is the highest currently available so pixel size is smaller. Accepted the contrast ratio is less than the fabled Panasonic but it is still acceptable at 1000:1. Also it is an interlaced display system but I see no mention of flicker from users.

    What are other people's views?
     
  2. CarlB

    CarlB
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    As you mention, the Alis panel is an interlaced display, so the spec of 1024 horizontal lines of resolution is completely off the mark for a start (compared with ProScan panels). A Pioneer with 768 horizontal lines of resolution actually has 768 distinct lines, whereas the ALIS panel only actually has 512, the other 512 being the interlace pair.

    Personally I have a Panasonic with only 480 progressive lines and it looks great with DVD. I think the reluctance with ALIS panels is due to most people wanting true progressive displays nowadays.
     
  3. cwick

    cwick
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    Chrise,

    I have the 32" Hitachi panel, which is an ALiS jobbie. I'd seen a fair number of anti-ALiS comments before purchasing, but I let my own eyes be the judge. I didn't see a better 32" panel while I was looking.

    The resolution of the screen is kinda strange. I understand why many posters seems to claim it's actually only 1/2 the quoted resolution - because it's an interlaced display. Yet, at the same time, ALiS panels *do* have that many addressable pixels on the screen.

    I distinctly saw this when auditioning panels. The Hitachi 32", next to a Panny 37", both being fed an average RF signal. One particular scene came up with a straight, sharp edge cutting a diagonal line across the screen. The Panny displayed it with a distinct combing effect (jagged edge) to the line as it moved across the screen. On the Hitachi it was perfectly flat. I chose to put this down to the higher-res on the hitachi (or smaller screen size, to be fair !).

    Other myth I've seen posted is that using a progressive scan signal on an ALiS panel is pointless, again because it is an interlaced display. That made sense to me - it seems logical at least. But I thought I'd give it a try anyway, just to see what happens. So I fed my 963SA into the Hitachi, and flicked between prog-scan and interlaced output from the DVD. Whaddya know ? I could see a difference. Not sure about the PQ - seemed to be much the same contrast and detail - but sharp edges were considerably improved, and the image had a more film-like quality about it. Although this was at about 3 ft viewing distance, so I'm not sure it counts. And, of course, my DVD has lots of life-saving features enabled when it's outputing progressive scan, so they could have an effect. But the end result is the same - I prefer the panel being fed an prog-scan signal, contrary to many comments posted on this forum.

    So after having lived with one for a week, I reckon ALiS panels are pretty good. And for the price, I reckon they're a bargain. If only it wasn't so noisy .....

    Cheers, Carl.
     
  4. eMonk

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    Hello there, :hiya: I've been lurking on the boards for a while now, but have only just managed to successfully register myself - the avforums mailing confirmation seems to have an issue with my normal email address. Anyway...

    as I understand it, ALIS panels do actually have 1024x1024 pixels. It's just that only half of them are actually switched on at any one time. Hence the "alternate" in the acronym. Therefore they are correct in stating that you see a 1024i image. As opposed to two 512-line ones displayed sequentially (if you follow me). Further, there is a little image on the product PDFs that suggests the interlacing is done in a checked pattern - now I can't be sure whether that is just a marketing diagram or not, but it would make a kind of sense. Anyway, as I see it, interlacing a plasma shouldn't be as bad as interlacing a CRT as you don't have a single electron beam scanning the phosphors and each half is all on or all off at once.

    Of course since I neither work for Hitachi or Fujitsu, I could be wrong...

    Of course, of course, I could be biased since I've just ordered a 42PD3000... :D

    Incidentally, I was wondering if the fact that the pixels are always illuminated may be the reason for plasma being more susceptible to burn than CRT? I mean, how long is an individual phosphor element actually excited for on a CRT in comparison? After all it's only actually going to be "on" for as long as it takes the electron beam to pass over it, whereas a plasma will be on for the duration of the frame.

    Cheers,
    Dunc.
     
  5. StooMonster

    StooMonster
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    The "sharp edges were considerably improved" will be because of the picture processing by the Faroudja DCDiTM chipset and Fajoudja Deinterlacer in your DVD player, not because of progressive scan per se.

    Many better / more expensive progressive scan chipset have image enhancement, anti-aliasing, artefact reduction algorithms than cheaper prog-scan chipsets (e.g. inbuilt in plasma, LCD, etc screens) lack. Futhermore, they may even use a totally different deinterlacing algorithm (e.g. motion adaptive vs field combining).

    Your test here is highlighting the difference between your player’s better prog-scan chipset and your screen’s not so good chipset.

    Some people have posted here saying that their ALIS screens produce a better picture when being fed an interlaced source, as the ALIS screen will digitise and interlace an incoming progressive signal anyway. You've highlighted a reason why using external progressive scan devices could work well with ALIS screens too.

    StooMonster
     
  6. cwick

    cwick
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    StooMonster,

    You've hit the nail on the head. The Faroudja bobbins are what I was referred to as "life-saving features", although in hindsight perhaps they aren't that good.

    They are selectable in the 963SA menus, but I couldn't be bothered to turn them off. Not exactly scientific, but then who is first thing Sunday morning ?

    But, as you point out, it does show that in some cases it may be worth feeding an ALiS panel with a prog-scan signal. Guess you don't know unless you give it a try.

    Cheers, Carl.
     
  7. chrise

    chrise
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    Carl B wrote
    "As you mention, the Alis panel is an interlaced display, so the spec of 1024 horizontal lines of resolution is completely off the mark for a start (compared with ProScan panels). A Pioneer with 768 horizontal lines of resolution actually has 768 distinct lines, whereas the ALIS panel only actually has 512, the other 512 being the interlace pair."

    I do not believe you are correct there are 1024 lines of information displayed as two fields of 512. Looking at the information that Hitachi and Fujitsu release it is clear that the number of horizontal lines is 1024.

    I have heard this before but stop and think if 512 lines of similar information was repeated one pixel lower 60 times a second the picture would be blurred at best and unwatchable at worse.
     
  8. paulS

    paulS
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    Hello All,

    Another newbie to the forum (been reading for a while now),

    I recently contacted hitachi to try and find what PC resolution would bypass the internal scaler of the 42PMA400,
    (I've now had 1 for 2 months & very happy with it)

    I think you might be interested in the response from Hitachi .........

    -----Original Message-----
    From: Peter Johnson [hitachi-eu.com]
    Sent: 28 April 2003 16:40
    To:paul Spicer
    Subject: PC resolutions


    Paul,
    The 42PMA400 uses Alis technology so the native resolution would be 1024 x 512. It is not one of the most common but graphics cards from Imagine Graphics and Matrox support this resolution. It can of course work in other resolutions but there will be some compression or rescaling.

    Regards
    Peter Johnson
    Technical Sales Manager
     
  9. cybersoga

    cybersoga
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    That wouldn't make a lot of sense, if it's native res was 1024x512 it wouldn't be interlacing anymore would it... I don't think you can do that, thinking about it, would it display the 512 horizontal lines twice and therefore it would not be interlaced any more because the alternating pixels will be the same?
     
  10. CarlB

    CarlB
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    That is exactly what happens with interlaced displays. Pause an interlaced image when there is significant movement onscreen and you will notice 'combing' around the edge of the image where the two interlaced fields do not match. This is exactly the blurred motion that true progressive displays do not suffer from, and one of the reasons that many people have steered away from interlaced displays.

    The following excerpt is taken from the well-known 'Secrets of Home Theater' website on progressive scan technology:

    So, as you can see from that a unique image is shown every 60th (50th for PAL) of a second, and that unique image will consist of half the lines useable by the interlaced display, so 512 for an ALIS panel. Contrast this with a progressive display (Pioneer 433MXE for example) which will display a full 768-line image every 60th of a second (NTSC).

    This is what I think the Hitachi tech guy was hinting at, that your PC should drive at 512 horizontal resolution at the panel refresh rate. By doing so you will drive field1 at 512 lines, then field2, etc.

    If you want to read more about the interlaced/progressive arguments then the article can be found here:

    http://www.hometheaterhifi.com/volume_7_4/dvd-benchmark-part-5-progressive-10-2000.html
     
  11. chrise

    chrise
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    I have read the article and do not agree it is saying what you think it is. The eye cannot resolve to seperate fields at 25 to 30 times a second and sees one field with twice the lines. A PAL CRT TV picture has 576 picture lines not 288 as you are trying to say. Each line is different than the one above - as two sub fields are shown there is some movement between each field so there are some artifacts from that.

    I totally accept that a 1024 progresive scan plasma would be better than the 1024 line ALIS system but none exists at the moment. My point is that to say all interlaced displays are inferior to all progresive displays without taking into account number of lines is a false conclusion.

    Go and look and see which system you prefer at the price point you can afford.
     
  12. CarlB

    CarlB
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    Of course the eye cannot resolve the two separate fields, I was never implying any such thing. However, what I am saying is that the two fields *do not* make a single image as with a progressive display. While the display may look pretty impressive without much action on screen, with fast action you get the same combing problems as with all interlaced display technologies. The saving grace is that the higher resolution (compared with CRT) makes these errors much less noticeable, but I still prefer a non-interlaced progressive display.

    It's all pretty subjective though, and admittedly I have not seen the Hitachi ALIS panel, only Fujitsu and Sony models in the USA.

    BTW, I have owned a Panasonic Model 4 plasma for over a year now, after viewing the ALIS panels mentioned above, and the Pioneer 433MXE, so I have actually looked into this for some time.
     
  13. Wilster

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    I've seen the Pioneer 433 and 503, Panny 5 series low res and the Hitachi screen running together. While not side by side it was still enough to form an initial impression of an analogue TV signal (an odd demo I know, but thats what I spend most of my time watching). I would order the pic quality...

    503
    433
    42PD3000
    Panny 5 series low res

    I would have loved to have seen the high res panny 5, but they didnt have one. The low res seemed to be rather too pixelated compared to the rest of the displays. The hitachi was good, almost on a par with the 433 but not quite. the 503 looked fab, but I cant justify that much cash on a TV!
     
  14. Joe Fernand

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    chrise

    I dont think the ALIS panels are dismissed completely out of hand but as we all learn more and more about our display and ways of improving our 'on screen' images then more and more we see that the inherent quality of the glass panel in the likes of Pioneer and Panasonic displays puts you in a great position to 'upgrade' your system by utilising better and better external (or internal) video processors.

    With ALIS panels you seem to have a hindrance in that these panels are conceived as a way of saving costs at the production stage and the interlaced nature of the panels means you won't get the big benefits to be had if and when you look to upgrading your video processor.

    Fujitsu developed the ALIS technology to reduce production costs and make their mass market panels more attractive to the IT industry - not the high end Home Cinema market.

    See http://www.fme.fujitsu.com/products/displays/pdptech.html (there are loads of similar articles on the Fujitsu site use the search function).

    Best regards

    Joe
     
  15. Blu-rayx

    Blu-rayx
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    :hiya:

    i've had my Hitachi pma400e for 3 days now and i'm well happy with it :D
    When watching sky you don't get any jagged edges,no flicker steady as a rock :D

    i was going to buy the panny5 but the flicker put me off

    i love ALIS panels :smashin:


    dvd
     
  16. CarlB

    CarlB
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    Here's some more info from the AVSForum FAQ on the resolution of ALIS panels:

     
  17. Darren Blake

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    I too have a response from Hitachi regarding the way the ALIS panel works:


    I should probably point out that I have seen and used a PMA linked to a PC at 768 vertical pixels and been happy enough with the results to buy one.
     
  18. ncpl

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    My 2p....

    As stated elsewhere a few weeks back, I found that Prog Scan into the Fuji HHA ALIS panel was significantly worse than interlaced from the same player. The player is a Meridian 598DP with DCDi chipset for the prog scan, so, I rule out source differences. When set to interlaced only, the PQ was excellent.

    On switching to a Pio433MXE, the Prog scan is immediately a clear winner over the Fuji (fed with PS). There is not as much difference between PS and IS on the MXE as there was on the Fuji. I think the MXE can de-interlace better than the Fuji could interlace.

    My conclusion was that the internal Fuji interlacing chips made the prog scan signal worse than an original interlaced signal straight from the player. Which means a waste of money on the player side.

    The MXE seems to have a greater depths or solidity to its images from DVD than the Fuji. Without being too tecky about this, I put it down to the higher genuine resolution compared to the 2x512 of the ALIS.

    The Fuji did have slightly better blacks but I don't actually find the MXE lacking now that I have tweaked a few settings.

    PS....I promise I won't mention the noise !!!!;)
     
  19. chrise

    chrise
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    Joe Ferdinand

    You make a good point that the aim by Fujitsu/Hitachi was to produce reasonably priced screens for the mass market - the press releases suggest they were targetting the domestic market rather than just IT. Fujitsu's pricing being somewhat higher than Hitachi or Sony for screens based on the same glass.

    On consideration the technology is not high-end in comparison with the 50 inch Pioneer screen fed by a full video processor- we can all dream.

    It is interesting that the screens appears to only display 512 lines when fed a progresive input which might explain the observed poorer than expected display from a high end DVD player. This is useful information and not clear from the specs.

    So in summary ALIS screens are a reasonable solution for many users but that true videophiles will look at more flexible solutions at higher prices. Would you agree?
     
  20. eMonk

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    Sounds about right to me. Personally, I could stretch to the Pio433, but to my eyes it seemed to have the traditional grey mist effect. Which no amount of tweaking seemed to reduce to a satisfatory level. Maybe this was just due to the fact that I was comparing against the Hitachi, but hey. Eventually, I came to the conclusion that the Hitachi was the best looking of the panels that I could afford (or rather *wanted* to afford). And if I sat around debating with myself any longer, I'd end up not buying anything and waiting for a proper panel to come out. i.e. something that has a resolution of around 1920x1080, can reproduce actual blacks and costs around four grand. Of course that's not going to happen for a while :(

    At the end of the day, by the time I come to buy a proper HD set up, I expect I'll be able to justify buying a new display anyway, and knowing technology it'll be twice the size for half the cost. At which point the Hitachi will get relegated to the bedroom TV :D

    You pays your money...

    Dunc.
     

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