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LED/LCD blooming effect. zone density on local dimming LED HDTV's need to be improved. ( at least on the LED HDTVs I have seen )


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#1 of 10 OFFLINE   jwilmes

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Posted July 21 2012 - 10:02 PM

I bought a 55-inch LED HDTV, the Vizio XVT553SV with local dimming from Sams Club in November of 2010. (after months of research) I have been very happy with the picture and features of the XVT553SV with the exception of the blooming effect in dark scenes like deep star fields in movies like Star Trek or movies credits at the end of films. I have also noticed this on other high contrast LED TVs. What sold me on the XVT553SV was the picture quality. The blacks are inky black (10,000,000 to 1) and the brightness of the screen can drive you out of the room if you crank the brightness level. But my favorite feature is the matte screen. Because the screen has a matte finish I almost never notice any reflections on the screen. We even have a wall of windows on one side of the room and watch the TV during the day without any issues. My one complaint on picture quality is the blooming effect. When you have a bright object on a dark field the object seems to have a halo of light around it. Does anyone know if any of the newer models have dramatically improved local dimming density. I think to improve this the local dimming areas need to be shrunk considerably. The specs for the XVT553SV say it has 120 dimming zones. I'm thinking 10 to 20 times that number of zones would not be over kill. I would think this would increase cost tremendously. Maybe there are other technologies that could solve this issue beside increasing zone density? Plasma HDTVs seem to have the best picture as far motion and color in my opinion (and blooming effects for that matter too). But the reflection from their glossy screens annoy me to no end. That or the coating they use to reduce reflection drops the brightness and contrast to unacceptable levels in my opinion. Don't get me wrong the Vizio XVT553SV has a really nice picture, but I'm looking for my next HDTV. The OLED TVs are still way too expensive for my taste but maybe that will be the answer in a couple of years.

#2 of 10 OFFLINE   schan1269

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Posted July 22 2012 - 04:11 AM

Blooming on a local dimming LCD will never go away. It is a nature of the beast. Even the best LCD with it have blooming problems. Until OLED kills of LCD and plasma...plasma is the only tech that won't bloom(other than DLP). Even LCD projectors can bloom. Essentially, until the time they can make each individual LED bulb behind the LCD crystal the "same size"...blooming will happen. LED lighting won't get there before OLED kills it off.

#3 of 10 OFFLINE   jwilmes

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Posted July 22 2012 - 06:56 AM

Sam I think your correct about OLED eventually killing off LED/LCD etc displays. It certainly seems OLED is the direction the industry is going for higher end displays and eventually lower cost displays. I also agree blooming is the nature of the beast until each pixel becames an LED element. My point is there is a massive difference between say 120 local dimming zones and the size they could reduce each LED element to. I would think the manufacturers have the technology to vastly reduce the LED elements in size, allowing higher density LED backlighting and allowing them to reduce the local dimming zones. Possibly along with reducing the size and increasing LED bulb density they could also employ other technologies to each bulb similar to what they do with dynamic edge lite displays just employed to each zone instead of the whole panel. I'm not sure of course if it would be practical or more importantly cost effect. I'm concerned research in the area may be orphaned because of the vast amount of resources being spent on the yet to be commercially viable OLED screens. (at least as far as HDTV's go, cell phones are another issue) My understanding is OLED screens may still have unresolved issues at this point. They may never be the preferred technology for well light environments and the lifespan of OLED displays are fairly short. It may be many years before these short coming are worked out if ever. I have not seen a large (50" plus) OLED screen in person yet. Are they really as good as the proponents of OLED claim as far as picture quality, brightness and anti-reflective screen capability? From what I saw from coverage at this summers CES the OLED HDTVs were displayed under very controlled situations.

#4 of 10 OFFLINE   schan1269

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Posted July 22 2012 - 07:18 AM

OLED works exactly like plasma...(in layman's terms)... The difference is... OLED IS each pixel being its own light source and color source(just like plasma). OLED is NOT an evolution of LCD like many people think it is. OLED has 5% in common with LCD(and that is only because of the backlight being LED on some models. LED still hasn't completely killed off CCFL ). It has more in common(over a functional standpoint) with plasma. Dupont has shown models that are phenomenal. But, they have yet to achieve "consumerable life expectancy". It is one thing to create a 2-3 year lifespan for a phone. Nobody cares. But a 2-3 year lifespan on a 50" display for your wall? Better only cost like $600. It is thought that the technology will get to the point that it almost won't matter "the size of the display". Dupont can just print out sheet upon sheet of the stuff. It is all economies of scale. All we are waiting on is the "longevity" to catch up to the "cost"... I would have no problem buying a new 60" OLED display every 3-4 years if the cost was under $800 a pop. IF it looks much better than a plasma. OLED will kill off LCD before it kills off plasma. Plasma can still get less expensive. I don't think LCD has time to meet the "cost per square inch" of plasma before OLED is knocking on the door.

#5 of 10 OFFLINE   jwilmes

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Posted July 22 2012 - 06:00 PM

Sam that is interesting about Dupont.. I didn't realize that Dupont was such leader in the development of OLEDs. I just wanted to thank you for your informed and insightful perspective. Man I can 't wait. Can you imagine buying a 60" high quality HDTV that's in the $800.00 range. Unfortunately my next HDTV purchase will be well before we get to that price range for a decent display. As far as the size of the display won't matter in time, I can see why the current HDTV resolution just won't cut it. I wonder what is after 4K? : )

#6 of 10 OFFLINE   jwilmes

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Posted July 25 2012 - 04:45 PM

Kevin, I look forward to reading your review of the Sharp Elite HDTVs. I believe that Sharp hired a number of the Pioneer Kuro engineers when the product line was shut down. I'm not sure how much of an impact that would be on Sharp Elite panels since they are LED and the Kuros were plasma. Now the $$$ for the Sharp are another story................................... Now that I think about it, I believe I heard Scott Wilkinson mention the Sharp Elite HDTVs last fall on one of his home theater podcast. That must be were I got the notion that they were going to be very good because Sharp had hired some of Pioneer Kuro engineers.

#7 of 10 OFFLINE   schan1269

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Posted July 26 2012 - 06:28 AM

Supposedly Sharp figured out how to do "variable" local dimming... As in each "pod of backlights" can be "swept" from lighter to darker.. The Sharp Elite will be an impressive LCD. With an even more impressive price tag(better not have just had lunch...and have a chair near by...)

#8 of 10 OFFLINE   Gregg Loewen

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Posted July 27 2012 - 12:57 AM

Hi guys. Kevin, looking forward to the review. Remember guys that there no perfect tv set. Each model and technology type has enherant flaws.

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