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#8589 - 01/11/05 12:21 PM Re: DLP tv's, Your view?
curegeorg Offline
Desperado

Registered: 11/15/03
Posts: 1012
Loc: Raleigh, North Carolina, USA
that texturing you are referring to, comes from the gridding system associated with pixels/points of intersection... this is a problem with all fixed pixel (pixel/cellular type) systems.

i would call it grainy, artifically so and not at areas where you typically see graininess (word??).

i have and still do like the overall picture of a crt lens based system for a big screen size. sharpness is less than some others, but the picture is more natural. thus i have a 65" rear projection Hitachi crt. there are better tvs i know, but i havent seen many that are much better for the same price range...

front projectors are going to be the solution in a few years... right now, traditional crt sets (glass monitors) are the highest quality, but for that increased quality you will sacrifice size (and budget for that matter).

lucky for us they are making some large leaps in tv quality these days.
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#8590 - 01/11/05 09:35 PM Re: DLP tv's, Your view?
tekdredger Offline
Gunslinger

Registered: 02/28/03
Posts: 142
Loc: Franklin, WI
Quote:
Originally posted by curegeorg:
that texturing you are referring to, comes from the gridding system associated with pixels/points of intersection... this is a problem with all fixed pixel (pixel/cellular type) systems.
No, that's not what I'm seeing. It goes beyond the pixel grid. And I see none of it on my new front projection system which is also a single chip dlp (HD2+). That's why I bought it. I'm convinced it's got more to do with the optical qualities in the rear projection screen material and diffusion lenses (perhaps in combination with the pixel grid on the higher resolution digital projectors). I think there is some diffraction taking place on a very small scale because sometimes these sparkly textures have a rainbow quality to them - like the sunshine on the snow that I mentioned. When I first noticed this I wondered if it was somehow related to the color wheel rainbow effect associated with single chip dlp's but since then I see the same/similar problems with lcd and lcos too, so it's probably not.
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#8591 - 01/12/05 10:10 AM Re: DLP tv's, Your view?
bestbang4thebuck Offline
Desperado

Registered: 03/20/03
Posts: 668
Loc: Maryland
In a former professional life, I was dealing with some very high-end front and rear projection, CRT, LCD and DLP based. In rear projection, because the projected image is on a short-throw basis, the rear projection screen usually consists of two or three layers. The first layer the light passes through is a Fresnel lens consisting of many fine concentric rings, each ring just slightly different from its neighbors, to focus the original spreading light beam(s) consistently forward. Among other things, this helps avoid, as much as possible, the center ‘hot spot.’ The next layer is usually a black-stripe lenticular lens meant to spread the image horizontally, so that the viewing angle is improved and the brightness is as consistent as possible horizontally. Because these lenses are often large and easily deteriorate with abuse (even skin oils transferred from your fingers onto the Fresnel or lenticular lenses can be seen as bright or dark spots, depending on the viewing angle), there is usually a third protective layer closest to the viewer that can take standard touching and cleaning during normal use and, should something scratch it, this protective layer can be replaced at about 20% of the cost of the other two.

In any pixel based light controlling mechanism, the pixels generated do create their own grid, whether obvious or softened. The sizing of this projected grid can interact with the Fresnel rings and/or lenticular striping lens, creating a minor irregular moiré pattern. Because the two interfering grids are separated by some distance, just slight changes in viewing angle and/or light source can influence what is perceived.

The advantage that CRT based RP has in this area is that the projection is a series of horizontal lines, and the red, green and blue colors overlap rather than being neighboring pixels or sequential pixels. Only ‘three-chip’ LCDs and DLPs have overlapping color pixels, and these are more expensive because of the number of chips and the optical mechanism/alignment needed to properly overlap the three colors. Three chip LCDs still have a ‘screen door’ grid pattern. Three chip DLPs are expensive, which is why most are single or dual chip with ‘time sharing’ of pixel time divided by a color wheel. The increase in DLP standards usually means faster switching between colors more often to try to eliminate the ‘rainbow’ effect. Because the CRT lines are horizontal, the Fresnel lens is ringed and the lenticular lens striping is vertical, there are almost no ‘nearly aligned’ patterns to deal with. The downside is that these overlapping horizontal scan lines must be kept in proper alignment both in reference to the outside world and in reference to each other. The more critical the screen viewing, the better this alignment must be. Also, the phosphors fade out more gently than pixels turn off – sometimes an advantage.

Bottom line: each method has its advantages and pitfalls. This is certainly not a complete discussion in that regard.

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#8592 - 01/12/05 07:04 PM Re: DLP tv's, Your view?
Hullguy Offline
Desperado

Registered: 01/17/02
Posts: 380
Loc: South Weymouth, MA USA
When I watched a DLP with the cartoons it looked awsome. When the salesman turned regular old tv it looked horrible! I've found this to be true of the LCD and Plasma screen tv's also. It gets better with a digital signal and knocks your socks off in HD!

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#8593 - 01/13/05 11:46 PM Re: DLP tv's, Your view?
curegeorg Offline
Desperado

Registered: 11/15/03
Posts: 1012
Loc: Raleigh, North Carolina, USA
well said bestbang. dont mention the word alignment and rptv in the same sentences though, alignment is its enemy.

normal def. tv does suck on most hd sets (except some crt tubes) and never looks as good as it does on better analog sets.
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#8594 - 01/14/05 01:17 PM Re: DLP tv's, Your view?
The Spatula Offline
Gunslinger

Registered: 06/04/03
Posts: 81
Loc: Southern California
Standard broadcast looks lousy on ALL HD TV's DLP, LCoS, LCD, Plasma and yes CRT. Simply put, they are made for HD or a really clean 480P signal, like from your DVD player.

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#8595 - 01/14/05 06:50 PM Re: DLP tv's, Your view?
rance Offline
Gunslinger

Registered: 06/09/04
Posts: 99
Loc: Boston. MA
I don't think standard broadcasts look any worse on HD sets per se, but they sure look like crap after watching HD broadcasts!

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#8596 - 01/15/05 11:15 AM Re: DLP tv's, Your view?
Hullguy Offline
Desperado

Registered: 01/17/02
Posts: 380
Loc: South Weymouth, MA USA
Granted about the quality of standard tv on HD sets. Unfortunatly, most of the medium available is still broadcast in standard def and should be considered when purchasing a TV.

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#8597 - 01/16/05 08:22 AM Re: DLP tv's, Your view?
NJtunastick Offline
Deputy Gunslinger

Registered: 01/05/05
Posts: 6
Loc: central N.J.
Arn't all channels supposed to be broardcast
in HD in the very near future? When that time comes do you think HD tv's prices will increase or decrease. Is this grainy effect barely
noticable? Because in the stores I never noticed
it, although I didn't know about it to look.
I asked someone at my work w/ a 50" JVC DLP,
and he said he dosen't see this on his tv.

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#8598 - 01/16/05 09:28 AM Re: DLP tv's, Your view?
NJtunastick Offline
Deputy Gunslinger

Registered: 01/05/05
Posts: 6
Loc: central N.J.
Just remembered, His JVC is LCoS type, if that means anything.

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