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Discussion Starter · #1 ·
Joe Linn and I have noticed something very interesting about the NEC LT100 DLP projector: the color saturation (and image in general) is noticeably better using the component inputs instead of RGB.


I've been using a progressive scan DVD player with my LT100, while Joe uses an IScan in RGB output mode and also a DTC-100 HDTV decoder. Both of our projectors have about the same number of hours on the bulb, and both have the gamma table adjustments I was working on earlier this year (now available from Cliff Plavin, aka ghibliss). I spent a lot of time making my LT100 look as good as possible, including calibration with a spectroradiometer.


Yet when I would try and adjust Joe's projector to match mine, the picture always looked more washed out, with muted colors and an overall greyish cast. No amount of adjusting the RGB settings got me what I wanted. It never occurred to me that RGB could look worse than component, plus the DTC-100 has only RGB output), so we spent a lot of time trying to get RGB looking right.


Recently I got a Skyworth DVD player with both RGB and component outputs. I was excited to try the RGB output with my LT100. To my surprise, the picture via the component connection looked MUCH better... absolutely no contest. No adjustment of the RGB settings could make RGB look as good as component.


"But wait, there's more." When using the RGB connection, I also saw a periodic tick in the motion, as if a frame were being held extra long every second or so. (Two scenes that illustrate this well are 1) the pan up from the puddle to the tree in the opening shot of A Bug's Life and b) the pan down from the churchbell before the wedding scene in Much Ado About Nothing.)


I had always noticed this tick in the motion on Joe's LT100, and had attributed it to the IScan or DTC-100. I never saw it on my projector.


The tick is totally gone when using the component video connection instead of RGB.


I thought I would mention this on the forum, since people are always complaining about the white section in the color wheel washing out colors, and occasional stuttering in the motion when using HTPCs with these projectors (LT100 and Plus UP-1100). It's likely that nearly everyone is using the RGB input, since it's the logical thing to do.


My honest impression is that the image quality via component is noticeably better for this projector. I saw the threads about the ATI Radeon boards now being configurable to produce component output. If you have one of these in your HTPC and one of these projectors, I think it's worth trying. You might be as surprised as I was.
 

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Discussion Starter · #2 ·
It just occurred to me that the LT100 may not sync to progressive component at 1024x768 without a slight modification to the signal table in flash memory (it's basically a list of supported video formats, with corresponding scaler parameters. You can make the projector support new formats by editing the table entries.)


Gary Gibbs and I have both spent some time trying to reverse-engineer the table format... not sure how far Gary got. I don't think either of us have a full understanding yet.


Maybe someone can confirm whether these projectors can already sync to high-resolution component signals.
 

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I noticed this as well with my Plus 1100. Using a Unity Motion HD stb I was able to switch between rgb and component (did it with the Iscan as well until I got rid of it). The 1100 has better color control off the the component input. As a result, I used an AA transcoder with my HTPC. I felt the improved saturation outweighed some of the artifacts that the AA caused; however, when I upgraded from a Matrox to an rfi-modded GeForce card, I felt it wasn't worth using the AA anymore b/c of the color saturation control from the GeForce card. Now I am using a Radeon, which has limited color saturation control (in fact none, I have to use the meager c/s control in Windvd to pump the colors up a little). Perhaps its time to use the AA again and see what happens.


Mark: specifically, where were you seeing references to component Radeon cards, I would be very interested.


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Jim
 

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Discussion Starter · #4 ·
jxo- here's the YPbPr direct from Radeon thread. I guess the consensus is that this is not supported yet. Hmm.


So your Plus has no trouble syncing to HDTV signals via component? That's good to hear.



[This message has been edited by Mark Fontana (edited 06-06-2001).]
 

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Mark: thanks. I will hook up the AA tonight and run the opening scene of Gladiator. I am not happy with the way the reds in the robes and the shields come through. The blue robe of the emperor and the grass color when Maximus charges through the woods are very undersaturated when compared to the rendition on the G90.


What's your assessment now of the Skyworth?


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Regards,

Jim
 

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Quote:
Originally posted by Mark Fontana:


Gary Gibbs and I have both spent some time trying to reverse-engineer the table format... not sure how far Gary got. I don't think either of us have a full understanding yet.
Hi Mark and all. I did work on the scalar reverse engineering for a day mostly for curiosity. Both of my components (GeForce and Dish 6000) only output RGB and seem to work fine with my LT100. When/if the Panamorph arrives I may have a need to figure the scalar out so that I don't have to switch between wideangle and normal using the projector when I go from HDTV (720P) signals to HTPC.


I have not tried component inputs and have no grounds for comparison.





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Gary


STOP DVI/HDCP!

DVI/HDCP! ~= HD-DIVX!!!

DO NOT SUPPORT JVC or anyone else who supports this!
 

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Mark,


This is REALLY good to know. I have been having trouble with the sync on my PLUS from my CI scaler from the beginning. This RGB connection is probably the problem. It is not there with direct s-video. So my question is: How do I do it? I do not have the adapter for component input, so where can I get one? Should I use the one that PLUS had as an option? Also, my CI scaler has a 5-bnc output only, is there a wire that converts? Any extra help here wouuld be great!!


Thanks again,


Jeff
 

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I was under the impression that the component input was limited bandwidth wise. I recall from speaking to a NEC tech that for 1080i, the RGB input was the way to go.

I consequently tried connecting the E*6000's component outs to the LT100, but it had serious sync problems. OTOH, it might have been wrong cable pin to pins because I made the cable by myself.


I also have the CI scaler, here I think that the CI is wired for either RGBHV or component from the factory, and is not easily converted from one to the other without having to send it back to the factory.


I am very interested in this thread at many levels.

I want to get better images from my LT100.


Andrew.


[This message has been edited by midi-guy (edited 06-06-2001).]
 

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I hooked up the AA transcoder in front of the plus and fired up Gladiator on the htpc (Radeon VE/Windvd 2.6.4). Color saturation is improved a LITTLE. Perhaps the Thumper mods have made the change less signficant. Still, the AA does some stuff to the image. The hue of the blues is affected with a pinkish tone (I can't adjust it out) but the reds are dead on. The 1100 would not sync to 85, 75 or 72 just 60hz. Sharpness seems a bit impaired but the ghosting I saw on text is less. Not as obvious an improvement as in Mark's case (again, gotta believe Thumper's overall improvement of color, including saturation, may be the reason). will leave the AA hooked for the next week or so and see how it fares.


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Jim
 

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Discussion Starter · #10 ·
midi-guy, I think you may be right about the bandwidth. I noticed the picture is a bit sharper using RGB.


Hmm... sharp, but cold and stuttery... or natural and warm, but fuzzier... too bad we have to choose.


I'll spend some time messing with the RGB-mode gamma table and scaler settings this weekend, but I'm not confident I'll be able to do much better. The ticking is probably something beyond our control.
 

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I also noticed huge improvements when using component mode on my Sharp NV7 DLP projector. Using an AA transcoder to convert Radeon based HTPCC and RCA DTC100.


My guess is that they use a separate colorspace map for a component input that is suited to video vs the RGB input, which tuned for presentations from a PC.


The RGB input banded quite badly, but with component it’s very smooth. The sharp has downloadable custom Gama settings, and I created a real pleasing ‘movie’ setting that does wonders for the resulting image.


Anyone with a ‘business presentation’ class DLP projector that supports component feed should try it out with a transcoder or native Component feeds.



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Jonathan
 
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