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Discussion Starter #1
I know there have been a few threads about this lately but I thought of getting some summary of the problem (and opinions) at this thread. What surprises me is that people in general doesn't seems to be bother by the problem. Rainbows and Chroma Bugs seem to irritate people more! This fact made me believe that my LT150 was damaged. Rainbows pop up at an average maybe 3 times per movie (my own experience) . The CB is more or less masked behind other scaling artifacts (yes, I'm not a HTPC user). This I can live with. But the dithering problem is there more or less all the times! It doesn't matter if the source is from LD, DVD or HDTV. It's extremely annoying!


So, I wonder if anyone knows the source of the problem and how it could be fixed/minimized?

For you guys that don't see it, how's your set up? If you are HTPC users and don't see it (or if it really doesn't bother you), have you tried to watch a movie the good "old" way from a DVD player. Was it more obvious then?
 

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Hi Rob,


I think we both know (and see) the artifacts (not only dithering, also crosshatching which I pointed to you when you brought the LT150 to my place) is a design flaw of any 1-chip DLP projector. TI the chip maker knows the problem and there are white papers on their website about the issue. Though it sounds TI thinks the motion artifacts are "feature" (to reduce frequency/bandwidth or some sort I don't know what they're talking about) instead of problem as I see it.


Your LT150 has THE SAME motion artifacts as the one I bought and CKL's. I saw THE SAME motion artifacts on the Plus Piano, Seleco 200DM, 2 Seleco 200, and the Sharp 9000.


People don't see (or don't want to see) the artifacts maybe due to:


1. They don't know what to look for (remember I need to point the crosshatching artifact to you to notice)

2. Their viewing distance is longer then 2x screen width. The long viewing distance make the artifacts hard to see. IMO they're missing picture detail too.

3. They think the artifacts maybe source related (MPEG2 artifacts) which is NOT.

4. They already think the picture (with all the artifacts) is good enough. They just enjoy the picture and don't care to talk about these motion artifacts.


I'd tried my best to push the issue. Still, no one care. scDLP is improving the rainbow issue but no one pay attention to the motion artifacts. I guess we can only hope in time the problem may be solved. :(


regards,


Li On
 

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The problem you're stating was really big to me with 1080i during motion. The LT150 aliases the 1920 horizontal pixels pretty badly. Putting the video filter "on" should help when you have the projector with component inputs. I run my HD at 720p because of this. The LT150 actually captures 720p with more resolution anyway.


Running the projector at XGA 60Hz also helps me out a lot. I do this with an HTPC.


I have had good success with my Dreamcast with its VGA output (640X480) which the LT150 upscales to XGA of coarse.


I watch from 1.7X to 2X the screen width back with very good results in all of these modes and I have pretty good eyesight.


-Mr. Wigggles
 

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Yes, it is the most annoying 'feature' of the DMD chip.


It' s a sort of noise on dark colors tham makes small 'waves' across the image, the quality of pans is also affected.


I find it very bad, and more and more i'm convinced that i will need a CRT PJ to achieve the perfect PQ i need.


My setup is with HTPC + DVI and i think i have reached the maximum PQ achievable, no other improvement is possible.


I' m afraid we have to live with it.


bye
 

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With a HTPC the dithering effect is made worse by certain software DVD players. I found that switching from WinDVD 2.6 to PowerDVD XP 4.0 improved things a lot, but it is still there and I do see it on other sources.


Jeff
 

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I am not familiar with the meaning of the word dithering.


I recently demoed the Sharp 9000 going through a 5K Runco scaler. I am pretty particular and I didn't see any motion artifacts. The only negative thing I noticed was at the beginning of the X Files movie there appeared to "scan lines" at several points during the promo for other Fox movies, THe scenes changed very fast and it looked like some of it was video and some film. A couple of people attributed to the "scan lines" as the scaler not applying 3/2 pulldown fast enough.


Is this the dithering problem you speak of? If not since I don't see should I learn what it is or is it better to remain ignorant and happy? Is dithering the kind of thing that if you don't notice it right away you probably won't notice it ever, or after I live with the 9000 for a while will it likely to become apparant? Any thoughts?
 

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Maybe Mr. Wigggles could give us his definition of "dithering". I sit slightly less than 2 screen widths back and have moved much closer to have a look. I see lots of problems using my proscan DVD player when compared to my HTPC, but I don't see dithering, at least that I am aware of - ignorance can be nice.


Audiophiles hear "problems" that most mortals either don't or aren't concerned about. $1,000.00 speaker cables may make a difference, but not enough for me.


When you guys get this sorted out and have the manufacturers "fix" this, let me know. I'll have another look. I probably won't notice the difference, just like speeding up the colour wheel didn't make a big difference to me. Untill then, I think I'll do what most of you seem unable to do - enjoy a great image!


If we were a picky with our friends and family as we are with this stuff - well, I think we'd be pretty lonely.


I fully realize that the motive here is to inspire the manufacturers to produce a better product, however, you also scare potential DLP owners away from a technology that has a lot to offer. Its this technology that is allowing HT to grow like never before - let's kill it before it has a chance to spread!


I have had some recent guests who were very relieved to find that: 1) the noise from my DLP wasn't anything as extreme as they were led to believe by this forum (floor mounted); 2) that "rainbow" wasn't an issue for them; and 3) standing a few feet in front of the screen they couldn't see "dithering". My response - you fail the AVS test, you're not worthy to be members - go home in shame! ;)


Cheers,


Grant
 

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The dithering he is speaking of is when the camera pans across the screen, and I notice it most in peoples faces, the colors in in the face will turn into bands of color until the pan is complete. Then all is good with the world. Then another pan, and the dithering in the faces declines, and you can see bands of color. I see it all the time, but I just ignore it. It doesn't bother me too much, but it would be great if I didn't see it!


Paul
 

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well, what would be great is to record a scene or two with digicam, put it on a weblink to be played so we can maybe illustrate further the dithering stuff. I see a lot of things I don't like with dlp ( the most recent i saw that troubled me was the Yahama DLP with FLUBBER and MOUSE HUNT scenes, I saw rainbows, artefacts, problems with adapting the 480p signal to its chip etc ). I saw the Seleco 300 and it was much better.


but all this seems to me much due to the one chip model or the mirror system maybe ? I would say the one chip technology.


too bad they can't sell us 3dmd for $10,000 :D
 

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I am assuming, as we all are, the 3chip would fix the problem because each chip would not need bandwidth savings because it is only dealing with one colour?
 

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I am glad someone finally got a response to this very

annoying problem with the LT 150.I have been posting about this

problem and thought either It was falling on deaf ears,people

didn't care or were in denial or I needed to visit my doctor

and ask for a Prozac perscription.I am a former CRT owner

that needed to go to a Digital projector for space.I am

sorry to deflate everyone bags here but the LT 150 is not

even comparable to the most modest entry level CRT Rig

I can deal with the lighter than Black blacks,the occasional

band or two but when I see the Dithering/Crosshatching/Matrix

effect every few moments That's enough for me.I have 25 hours on my LT150 and I can guarantee you the meter will never hit 30

hours I am going back to a CRT I will find room for it.The single chip dlp's are not ready for primetime better than lcd but still

not there yet

#1 CRT

#2 CRT

#3 CRT Video grade

#4 DILA

#5 DLP

#6 LCD
 

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the denial factor in video especially is a strong one. if I'd own a dlp, i would deny also. I own an lcd and I admit without any problems the strong inconvenient of the technology, especially pixelisation since mine is not very bright, black level is not as much a problem as a 1000ANSI one. but I'm working on getting a CRT too since I would like to view movies at 1.33x the width and not 2x


now, is dithering influence by the type of color wheel ? RGB vs RGBRGB ? I had much better impressions with the 6segments Seleco. or is the color wheel only a matter of rainbows or "no" rainbows ?
 

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I would think a faster color wheel would require more bandwidth in the DMD chip. The DMD would have to have a frame of data for each section of the color wheel. So six frames worth of data would have to be shuffled for each rotation. Plus the bits are already being modulated (turned on and off) with timing pulses to provide the greyscale, so this is even more data.

http://www.dlp.com/dlp/resources/tech_over.asp


I don't understand why there aren't less expensive 3 chip designs. 3 LT-150's @2500 = 7500...


However for a 'data' business projector, the dithering artifact is really a non issue.
 

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hi


too bad we can't get a real, non misinforming, true and honest answer, at least technical, as for why 3DLP at lower prices can't get sold to the public. as far as i remember, digital cinema never caused the dithering effect if I remember correctly my TS 2 viewing but the way data and the type of data differ quite a lot from what we use in our HTs that I don't think this is valid enough a reason ( wow, what a long sentence ! :D ).


a 3dmd is a bigger machine for sure ( have not seen anything lighter than 45lbs ) and thus, this could be one of the big reason it's commercially no wise as far as industrial consumers are concerned.


maybe the WAF ? :D : "honey, I want a big nice image but it must be almost an invisible projector !"


lol !


I think 3DLPs at $10,000 and under would be a tremendous success, IF the recession was not there, so , patience............
 

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I Agree

a 3 chip DLP would make the digital projector a worthy contenders

for Serious HT.I think the problem is manufactures are making

good margins on the single chip projectors and bean counters

are giving you what you want Cheap Crappy Projectors

Its no different than buying a car you can buy a KIA and get to

your destination or you can Buy a Caddy and get there in style

Putting fancy rims on the KIA will not make it ride any better.

My point being If you take a projector designed to be used in the

business world (mostly static images) Feed it what ever source you want HTPC,Progressive DVD,High end Scaler ect.. under it all

Its still just a business projector.Manufatures have proven they can get it right but fail to do so Look at the Sony W400Q from

what 5 years ago? 16:9 panel with delta design,Sure it was

a little dim and the CR was a little low but hey $3500 for a plug and play projector that for the most part considering its age

rocks.If Sony could do it 5 years ago then manufactures with current R&D and chip set prices and low overseas labor rates can

certainly do it now They just don't want to $10k for a single chip DLP is plain Horse S*** I dont care if the case looks like a

sports car

Cheers Ray
 

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I see dithering too - best described as regions on the screen starting to look like chessboards (i.e. alternate pixels go dark and bright) ONLY during pans. This became obvious after I switched from a white wall to the High Power screen. I have come to accept this as a shortcoming of single chip DLP and will live with it. The LT150 produces a superlative image in all other respects. Colours are very vivid and true, the projector is a breeze to set up and use, and the blacks are more than adequate in all but the most demanding low contrast shots. Contrary to Ray, this LT150 will give me and my friends many hundreds of hours of movie viewing pleasure before better technology comes along that can deliver bang for buck in the manner that this little projector has done for me. I am glad I bought the LT150 sight unseen during the Dell offer. Even though I can consider myself a CRT hugger (after all I still use an excellent Sony 27" PVM monitor for a lot of my TV/video watching), and know a good picture when I see it, the LT150 now rules when it comes to movie watching (warts and all). It's driven by a Panasonic RP-56 DVD player.


If you are a newbie looking for that first front projector, don't be put off by threads like these and ignore what is for all purposes a mighty fine piece of hardware, given what is currently available out and there and how much they sell for. Go and see a demo and make up your own mind.


I would like to add that if someone doesn't see dithering with a single chip DLP, it doesn't mean that they are in denial (as some posters here suggest), or that their visual acuity is impaired in some way. Maybe they are simply too busy just enjoying the film.
 

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Just a question - how come the CRT guys (and I don't give a damn if they own a digital projector) can come onto this section of the forum and dump all over digital projectors - in this case DLP?


How about a ton of the digital guys go onto the CRT section and start a real fight! I bet we'd be censored in a nanosecond! Where are the moderators?


And who said projector racism isn't alive and well and living on this forum!


I am seriouly looking for a CRT projector - it had better be perfect, because if not, I am going to raise hell!


Cheers,


Grant
 

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Ray


I hear you! I still have that old Vidikron Crystal one which uses the same delta pixel configuration that made the glory years of Vidikron, Sony and Philips when they ruled the lcd market years ago: smooth, vga-type CRT like images, yet still having some difficulties at times with blacks. My old lcd gives a workout to many current lcd and dlps projectors (resolution aside) in terms of smoothness, naturalness, colors, even brightness with only 270ansi! :D and without htpc or progressive player, just rgb on bnc inputs ,as the VP400. and this was manufactured in 1993! no dithering, no rainbows, stable detailed background details, no harsh pixelisation ( but this ain't a well calibrated crt ! let's be realistic )


ok, it's big and heavy but quite silent. 50lbs, ok.


but I'd rather have a big nice machine such as a 3DLP instead of a 2lbs projector's that would give brain headaches and visual problems with rainbows, ditherings etc. it seems to me that the discoveries or the experiences of the past have been lost some way, some how. the delta pixels arrangement for video lcd projectors was one hell of a great system. but the computer-multimedia market is nr 1 priority so far. It's changing a bit I think with the growing home theater market.
 

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Hi

I'll tell you why #1 You have no argument to go over to the CRT

forum at least not until the Digitals are close to CRT

I was not dumping on the Digital Projector form I have 2

digital projectors.You can sugar coat it all you want

but its time to call it like I see it and in absolute terms

you can do better image wise with a $1000 CRT projector

and it doesn't have to be perfect to clean the 150's clock

That is if you are interested at all in True film like representation

If you are critical or have high expectations like I do

then The LT150's Matrix/Dithering/Banding/Rainbows,ect..

just wont cut it.I highly recommend that all who are interested in this projector see it in action to see if you are sensitive to these

anomaly's Buying this projector on hear say might cost you dearly

If I have to be politically correct and be a band wagon jumper

in this forum then I will find somewhere else to post what is my

opinion on HomeTheater Related products

Cheers Ray
 

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Ray


stay here! we shouldn't tone down our voices for christ sake!


it's as if I'd stop ranting about the dd vs dts non sense and biased opinions I see on various sites ( ie, dts is crap, dd rules ! these guys claiming that must ge paycheck from dolby !).


mono chip dlp is big compromise technology, with more side effects than a good "video oriented" 3lcd i'd say.


except perhaps the SELECO 300 and the SHARP 9000 ( maybe )


argh! if these babies where cheaper!!! ( as in
 
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