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Discussion Starter · #1 ·
Howdy, does anyone have some ideas about ways to getting rid of some of the "mosquito" effect that can happen on these tvs? Are there any user or SM tweaks that can help to make it go away? Thanks for any info.

-Chris
 

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Quote:
Originally posted by segami
Howdy, does anyone have some ideas about ways to getting rid of some of the "mosquito" effect that can happen on these tvs? Are there any user or SM tweaks that can help to make it go away? Thanks for any info.

-Chris
swap out the lamp in set with one of those yellow outdoor bug bulbs :D
 

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Quote:
Originally posted by ted08721
swap out the lamp in set with one of those yellow outdoor bug bulbs :D
LOL:D


But then of course you'd have the zapping noise instead of the fan...along with some supernovas instead of rainbows.
 

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Discussion Starter · #5 ·
Perhaps it is the screen door effect, but I'm not sure. What I'm seeing is that the background on a still image is constantly shifting kind of like a bunch of mosquitos in the air, is that what the screen door effect is (which I thought was more of something like you saw a grid pattern across the tv if you sit too close). Can anyone straighten me out on these terms?


-Chris
 

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I think that is "dithering" and is the result of the compression of your signal. Do you see it on DVDs ?


Ken
 

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The "mosquito" effect is not the same as the "screen door" effect. The "mosquito" effect, as I understand it, refers to small dots that appear to "swarm" over objects (usually dark colored objects) when the Samsung has to dither the color of the object. Don't know if it can be adjusted out.


Dithering is a technique that is used to artificially increase the apparent color depth of a display. Say you had a display that could only create 256 colors. You could give the appearance of extra colors by mixing pixels of two different colors. For example, a rectangle containing a checkerboard pattern of colors 255 and 256 would appear to be a color in-between 255 and 256. Dithering is actually not that simple. A checkerboard pattern is the simplest example of dithering, but what usually really happens is that pixels of a second color are scattered through a field of the first color. By adjusting the density of the second color's pixels, different shades of "combined" color can be produced.


The disadvantage of dithering is that the spatial resolution of the image is decreased. If you take the example of a checkerboard pattern, you are using two pixels of a different color to create the illusion of a single pixel of a "combined" color. You have roughly halved your resolution. Therefore, a dithered picture will probably appear somewhat softer than the full resolution version would.


Another disadvantage of dithering is that, if you stand close enough to the picture, you can see the individual pixels that are making up the "combined" colors. This is the "mosquito effect" that people see with the Samsung DLPs. You can VERY CLEARLY see this if you compare a Samsung DLP to nearly any other type of display device. The difference is especially noticeable when comparing the Samsung to a RP-CRT television. The best place to look is in dark-but-not-completely-black areas. You will see dark pixels combined with a smattering of lighter pixels. If you press the freeze button on the remote and then step back, the lighter pixels will fade into the field of black and you'll see the "combined" color. However, for me, this tends to make the Samsung's picture look softer than other displays--which is a bit contradictory since its pixel-based nature actually gives it the ability to create very sharp edges! I guess I would say that the Samsung DLPs have sharp, well-defined edges (e.g. on text) but softness within a single field of color.
 

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Quote:
Originally posted by kenhdtv
I think that is "dithering" and is the result of the compression of your signal. Do you see it on DVDs ?

Ken
Dithering may be the result of signal compression, but I have compared the exact same HD signal on a Samsung DLP, a Hitachi LCD-RP, and a Mitsubishi RP-CRT. The Samsung had heavily dithered picture, the others had none. I believe that dithering is inherent to the Samsung's.
 

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Quote:
Originally posted by loraan
Dithering is a technique that is used to artificially increase the apparent color depth of a display.
In the attached picture, you can see the areas where dithering has been applied. If you zoom into the picture with a picture viewing program, you will see the individual pixels that are being combined to make up the colors. The Samsung isn't quite this bad, but to me, it is distracting.
 

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Quote:
Originally posted by loraan
The Samsung isn't quite this bad, but to me, it is distracting.
Actually, that's an extreme but VERY accurate example of what I see during camera pans on the Samsung DLPs. I've tried to explain this motion dither problem with words several times, but this picture is a perfect example of what can happen to the Samsung DLP picture during pans. During pans, the TV seems to have to increase its dithering, resulting in a kind of grainy and banded looking picture similar to this Trinity pic. The distortion where the orange background meets the vertical gray bar is an especially good example. Step back far enough from your monitor and Trinity looks fine, just like DLP mosquitoes, clay faces, and motion dither tend to disappear at farther viewing distances. During still shots, I've never seen Samsung DLP dithering get anywhere near as bad as on this Trinity pic, but during pans this is what I see.
 

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Quote:
Originally posted by DLiquid
During still shots, I've never seen Samsung DLP dithering get anywhere near as bad as on this Trinity pic, but during pans this is what I see.
Just to be clear, I intentionally made the picture's dithering especially extreme so that it would be clear what dithering was. The Samsung never looks as bad as Trinity there. For me, it's impossible to see the actual dithering at normal viewing distance, but if I put the Samsung next to a RP-CRT or RP-LCD picture, I can see an overall difference that I attribute to dithering. I describe it as a kind of "softness of colors". The edges of objects are sharp, but fields of color within the object lack definition. It is difficult to describe.


I believe that "banding" or "clay faces" could also be caused by the same lack of color depth that would cause the need for dithering.
 

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I agree, that's a good approximation of it, which is why I wasn't able to live with my HLN617W, since it drove me nuts. In my case I actually did find it to be as strong and obvious as it is in that picture too from even well beyond my viewing distance of ~10 feet, so you really didn't exaggerate it that much IMO. :p


I also posted an approximation of what motion dithering looked like (with a picture of Seinfeld's head) back when I was also trying to describe what it looked like but I think this example is even better than mine was.
 

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Quote:
Originally posted by Googer
my viewing distance of ~10 feet
With the 617W, I'd think you'd have to move back a few feet further than that for the dithering to disappear; it was bothering at me at ~10 feet with the 507W, but I felt like at 13 or 14 feet it might not be an issue (my room wasn't that big, though). I think a lot of the debate regarding motion dither, mosquitoes, and clay faces has to do with screen size and viewing distances (and perhaps eyesight ;)), which is why I thought it was interesting that your 61" viewing distance seemed pretty close. It is a fact that if you are far enough away, you will not be able to see these things, although loraan might be right that you might be able to perceive a difference in resolution even if you can't see the dithering.
 

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Quote:
Originally posted by DLiquid
It is a fact that if you are far enough away, you will not be able to see these things, although loraan might be right that you might be able to perceive a difference in resolution even if you can't see the dithering.
I agree that dithering should be pretty much invisible at appropriate viewing distances, although I maintain (pending double-blind confirmation) that in a side-by-side comparison, I can see a difference between a dithered Samsung and a non-dithered CRT. But the "banding" or "clay faces" is much more extreme and is apparent to me even at appropriate distances.
 

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loraan,


I've found that some of the artifacts are caused by the lack of quality of the source material. On our 507, some DVD's look excellent. Some do not. I've examined certain scenes of a DVD on our 507, then examined the same scenes on our 32" CRT. The image defects are usually visable on the CRT also, but not nearly as noticeable. I'm thinking the solution to our image issues is better source material. JMHO.
 

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I agree that going further back may mitigate the dithering problem, but notice I said "well beyond" my normal 10 ft viewing distance. In fact, the furthest I could view my HLN617W from in my apartment was about 20 ft away and I could still see it. Also, now that I know what to look for, it's plainly visible to me on CC's in-store HLN437W even from about 15 ft away, which is getting (IMO anyway) painfully small to watch. :p


I'm not positive if clay faces are source-dependent or if they're a minor occurrence of temporal dithering. Most people claim to see clay faces on occassion but not too many seem to notice temporal dithering.
 

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Quote:
Originally posted by Googer
I'm not positive if clay faces are source-dependent or if they're a minor occurrence of temporal dithering. Most people claim to see clay faces on occassion but not too many seem to notice temporal dithering.
I suspect most people wouldn't know what dithering was if they did see it. The sales guy I pointed it out to said, "oh yeah--pixellization". I explained the difference, but felt like a bit of a pompous ass afterwards.


The clay faces (which I'd prefer to call "banding", since it happens on things other than faces) may be mitigated by the source material's quality, but it's not entirely source dependent. I put the same DVD up on the Hitachi LCD, the Sony XBR (LCD), and the Samsung HLN61. The Samsung had WAAAY clay faces; the others had smooth, even facial gradations.
 

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Yesterday I watched the CBS NFL game in HD on my Sammy 43W DLP, I saw a far amount of dithering. Tonight I watched MNF, and saw no dithering. The signal strength between my CBS and ABC station is significant. I have to say that this is not a Sammy problem, at least for me. I am encouraged by this. BTW, MNF is excellent in HD on this Sammy. I could not be happier, plus the Packers are going to win.
 

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Quote:
Originally posted by James R. Geib
Were these problems noticed on a properly calibrated DLP or without going into the service menu??
All of the comments in this thread so far are based on store display units. They either had default factory settings or whatever settings the last buyer left them at. In most cases, I made basic adjustments to the sets before viewing (e.g. used a dark area to adjust brightness, turned off digital enhancements, set color temperature to whichever one I liked best, etc...).


Regarding the Samsung DLP specifically: if anybody can point me to a thread where somebody manages to tweak out the dithering and banding, I'd love to see it. I'm trying not to make any definitive statements--just to report what I'm seeing as I shop around.


Unfortunately, it is unlikely that I (or the average buyer) will get to see a fully calibrated HLN before I purchase. But I'm not getting to see a fully calibrated Panasonic or Hitachi either, so in a way, that's fair. Each set manifests its own strengths and weaknesses.
 
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