The irony of my ISF calibration

Discussion in 'Displays' started by Cameron Yee, Apr 14, 2004.

  1. Cameron Yee

    Cameron Yee Executive Producer
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    First a disclaimer. This is NOT meant to discourage the investment in an ISF calibration, especially from experts like our own Michael TLV (who did my calibration). If anything, it shows exactly what a display fails to show a person pre-calibration, what a calibration is capable of revealing. Plus I need to share my pain [​IMG]

    So I had my 42" Toshiba RPTV calibrated the other day, but sadly it revealed I have been the victim of burn in. If anyone can tell me differently I'd appreciate it. If it is truly burn in, I honestly have no idea how it happened. Followed all the rules about brightness and contrast, static images, calibrated with VE, the whole thing.

    The effect can be seen here.

    I verified the problem is in the CRTs by opening up the set and looking into the guns. There was that curved line.

    Now the kicker is I didn't notice this until after the calibration was done, meaning that the shape (if I'm intepreting things correctly) was buried in the lower end of the grayscale. Right now it is only visible at certain screen brightness levels. It is not visible in scenes with high brightness or deep shadow, only when brightness seems slightly below average. From what I've read about burn in, this does not seem to be typical, which puzzles me and makes me question if it is in fact burn in.

    Anyways, there seems to be nothing to be done, whether or not it is burn in (one just seems to reflect on me as a careful owner). I'm going to see if I can live with it. The calibration looks great - shadow detail can be seen that could not before, everything looks much sharper. However I have considered perhaps rolling back the grayscale to what it was in order to obscure the shape. I have to make a sacrifice of some kind and it comes down to which is the more acceptable one. Any input appreciated.
     
  2. Guy Kuo

    Guy Kuo Supporting Actor

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    I don't believe it is burn-in of the phosphor. That would be visible in higher APL material and more difficult to see in low APL material - the opposite of your situation. The artifact is more likely low level noise that is now visible because the blanking level of the tubes is now takes place at a lower signal voltage. This reveals more shadow detail, but also can make some low level noise in the system design visible. If you could get an image of the artifact with a full screen 10 IRE field rather than a movie scene, we could more readily pick out what is artifact vs image detail. That might make it possible to identify what kind of noise we are seeing. There is too much other stuff going on in the image you posted to make things readily apparent.
     
  3. Michael Reuben

    Michael Reuben Studio Mogul

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    It if were burn-in, that would mean you've been displaying a static shape with that cuvered line for long periods of time (as can happen with, e.g., the sidebars on a 16:9 TV). It seems unlikely.

    M.
     
  4. Cameron Yee

    Cameron Yee Executive Producer
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    Thanks for the thoughts thus far. Having a somewhat limited knowledge of what can affect CRTs, burn in was the only thing I could think of but then, as I mentioned, it just didn't make sense (opposite behavior, etc.). I assume the 10 IRE field is available on Digital/Video Essentials, but it seems it's not called that in the guide. Can you refer me to the chapter and I should have something up later tonight.
     
  5. Cameron Yee

    Cameron Yee Executive Producer
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    If it helps, the problem is also visible with other sources, not just the DVD player.
     
  6. Danny Beck

    Danny Beck Stunt Coordinator

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    I know the THX Optomizer has a circle patern that looks similar to the one in your photo. [​IMG] Have you ever used that pattern from the optomizer?
     
  7. Cameron Yee

    Cameron Yee Executive Producer
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    I don't think I've used anything except VE, but aside from that, there are several other reasons why the THX pattern would not be the cause. The THX circle is centered, whereas the shape on my set is on the left side. The shape on my screen is also not a complete circle. The pattern that burned it in would also have to be a solid, negative image of what's seen, meaning the dark areas were created by something bright and static for a long period of time (even longer since I've never had my set on torch mode).
     
  8. ChrisYK

    ChrisYK Stunt Coordinator

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    Could it be some sort of reflection artifact?
    Like the others said, unless you had a image with that curved line sitting on your screen for long lengths of time, I don't think it's burn-in.
     
  9. Cameron Yee

    Cameron Yee Executive Producer
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    I took a pic of the screen displaying 20% Flat Field from Digital Video Essentials and posted here.

    I also reconfirmed the artifact can be seen looking directly into the CRTs (well, with the lenses located between myself and the CRTs still). Not easily visible in the Red but visible in the others.

    Out of curiosity I tried fiddling with the HPOS to see if the artifact would move with the image. It stayed in the same spot. Not sure what that proves but I thought it would be worth knowing.

    Edit: Continuing through the subsequent chapters on DVE, artifact diminishes in visibility as APL increases to 100%.
     
  10. Guy Kuo

    Guy Kuo Supporting Actor

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    It if doesn't move with the image as you adjust HPOS, then it is unfortunately a phosphor burn. A signal noise issue would typically shift left/right with the HPOS control. Do those two narrow, vertical dark bars on the left move with HPOS? Those bars look like ringing noise from the horizontal retrace. Still very atypical for it to diminish as you go up in APL. I don't have a a good explanation for this.
     
  11. Cameron Yee

    Cameron Yee Executive Producer
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    The vertical bars are a bit overapparent in the photo. It actually looks more like one big shape, which reminds me of those cut out graphics they do for local affiliates to do a news teaser during network show end credits.

    I'm having trouble believing this is a result of my being careless, because I haven't, which makes me wonder if this is something that slipped through QC at the factory (given that it wasn't visible until calibration). I would like to know the reason, but ultimately I'm stuck with the same set of decisions.

    So how much does a replacement of the CRTs cost? Would it be better to save the money for a front projector?

    And I think I might just try rolling back the settings a bit to see what that gets me. Sadly, the main issue I had with the picture was the lack of shadow detail. But now it's a question of which is worse in my eyes - seeing the shape when the APL hits that 20-40% range or giving up shadow detail in the overall picture. Fortunately the shape is not smack in the middle of the screen and if I essentially watch the movie I don't really "see" it (along the lines of the advice we give people who have trouble with the "black bars" in widescreen formats - watch the movie, not the black bars).

    I think Michael kept track of the previous settings so I'll see if I can get those from him and do some fiddling. If anything else occurs to anyone, I'd appreciate hearing it, even suggestions on a replacement display in the $1000-$1500 range. I'm thinking more about projectors now and have looked at the X1 (currently priced at a paltry 900.00 after rebate) and the Panasonics. Since I have a Bravo D1 I would like something with DVI, which I know the Panasonics have.

    Thanks. Any condolences and sympathy gifts accepted [​IMG]
     
  12. JohnnyG

    JohnnyG Screenwriter

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    What you're seeing is caused by the Fresnel lens - part of the screen assembly. It's 'normal' and there's nothing you can do about it. Actually, I'm surprised you never noticed it before, but then again, you're looking at the picture whith a whole new eye now.
     
  13. Cameron Yee

    Cameron Yee Executive Producer
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    Hmm...that's what Michael said initially but I thought because I could see the shape in the CRTs it was something on the CRTs (i.e. burn in). So you're saying it's a lens artifact and that if I removed the fresnel I wouldn't see it in the CRTs?

    Truly, how "normal" is this? I'm no expert by any means, but of all the issues with RPTVs this is the first time I've heard about this one.

    It's definitely something I didn't notice before. I wouldn't say it's my looking at the picture differently, it's that the picture IS different.

    Edit: Again, knowing (thinking) it's not burn in makes me feel better.
     
  14. JohnnyG

    JohnnyG Screenwriter

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    I actually missed this part of your post (or it didn't sink in). Are you absolutely certain about this?? I've noticed that exact same curved line on the screen a hundred times on that model and I'm pretty much 100% certain it's from the Fresnel. You certainly shouldn't see it on the face of the CRTs though.

    So if you see it on the CRTs, is it on all 3 CRTs? If so, then forcing a misconvergence should show the line in 3 different colours. Please confirm this.
     
  15. Cameron Yee

    Cameron Yee Executive Producer
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    Well, I'm PRETTY sure I saw the edge of the curve on the CRTS, not necessarily the whole shape because of seeing all of one color. Certainly harder to see in the red.

    I'll try the misconvergence though - good idea. I like it better than cracking the baby open every time. I'm afraid I'll start stripping the plastic screw holes. What would be the best way to go about this? If I can just move one of the CRTs it should be evident.
     
  16. JohnnyG

    JohnnyG Screenwriter

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    Just go into the convergence screen and purposely misconverge.
     
  17. Cameron Yee

    Cameron Yee Executive Producer
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    Well, I shifted red and blue in the convergence menu and looked at the 20% field with VE. Hard to tell initially, but after my eyes adjusted I could see three separate curved lines, though they weren't especially distinct. The edge of the shape was essentially blurry though. So I guess that confirms the shape being on the CRTs. HOW it got there I am still quite puzzled over as well as the atypical behavior as a burned in artifact.

    In actual viewing I'd say I notice the thing 15-20% of the time. Clearly I wish it weren't there at all, but for what it is it's not so bad. There is much that is very good about the picture when the APL is not at that particular level.

    Not sure what to do - whether to essentially start over and get a projector, get the guns replaced or just live with it until I'm in a better position to replace it. I do feel a bit soured by the whole CRT RPTV thing, so for my next display I really don't think I will go that route.
     

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