D-ILA: Why SXGA3 over SXGA1/2? - AVS Forum
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post #1 of 8 Old 04-28-2001, 08:13 PM - Thread Starter
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I'm just wondering by are people so concerned about getting 1365x1024 resolutions to drive a D-ILA, since you can drive SXGA1/2 inputs at 1280x1024 with Resize:Off and still get pixel-accurate output?

I'm wondering if I'm missing something....

Andy K.
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post #2 of 8 Old 04-28-2001, 09:08 PM
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Quote:
<font face="Verdana, Arial" size="2">I'm wondering if I'm missing something....</font>
About 80 pixels.

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post #3 of 8 Old 04-28-2001, 10:20 PM - Thread Starter
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http://www.avsforum.com/ubb/smile.gif Thats what I thought. So why the big deal over custom T&Rs for HTPCs, and specific D-ILA modes on scalers? I suppose its nice, but it wouldn't make much difference to me one way or the other...

Andy K.


[This message has been edited by kromkamp (edited 04-29-2001).]
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post #4 of 8 Old 04-29-2001, 05:53 AM
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Actually, with the SXGAi RGB inputs, resize is always to ON and cannot be changed. And using SXGA1 or SXGA2 with a Faroudja set to 1280x1024 not only loses some pixels left and rigt, but also gives a slighlty distorted picture.

In theory, the Faroudja processes the signal in the digital domain, and recreates 1280 pixels from the input. Then it converts them to analog, sends them to the projector, who scales the signal into 1365 pixels. The 1280 to 1365 mapping must introduce some artifacts.

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post #5 of 8 Old 04-29-2001, 10:36 AM
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One of the places the D-ILA's internal scaler is excellent is with 1080i material. Keep in mind that the resize switch is not available when feeding the projector 1080i or 720p. From what I understand the projector is not as good at scaling native 720p to full panel resolution. Something magical with the 1080i hybrid interlaced/progressive scaling method.

Resize should be available on all computer based resolutions (both comp1 and comp2), but SXGA3.

Since you cannot shut off the resize switch for HDTV inputs, this may create a situation where scaled NTSC material is less wide than the HDTV image. A good example: If I fill my full screen width of 107 inches with an HDTV image, the corresponding scaled NTSC image from a HTPC or Scaler (at 1280*1024)will be approximately 100 inches. I realize you can use the zoom or the tracking control to try to compensate for this, but does not allow for optimum usability.

Just one other issue, the SXGA3 source resolution of the D-ILA has received more attention with regard to creating pixel perfect timings with both HTPCS and at least one scaler (The Rock). A known quantity-with full panel resolution and a 75hz refresh rate.

Just my 2cents.



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post #6 of 8 Old 04-29-2001, 10:44 AM
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Don,

As a matter of fact, you get better results with a Faroudja outputing 1080i than 1280x1024. That's not logical, because 1280x1024 should be closer to the native resolution panel, and with 1080i the D-ILA is scalling down a signal which has just been scalled up, but that's what I saw on numerous occasions.

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post #7 of 8 Old 04-29-2001, 02:34 PM
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Robena,
I cannot comment on the outcome of the Faroudja with D-ILA at 1080i, but this is not the case with a HTPC, DTC100 or other scalers (CI, Quadscan)I have tested the projector with at 540p. I would say you are experiencing the magic of the faroudja's ability to clean up nasty NTSC.
Just for the sake of accuracy, I was describing a situation where the input was native 1080i material at 1920x1080.

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post #8 of 8 Old 04-29-2001, 09:06 PM - Thread Starter
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I am able to turn Resize off on Computer input #2 (RGBHV). I havent tried #1. This is feeding a 1280x1024 signal to the projector. You have to make sure to feed &lt; 75Hz, otherwise it uses SXGA3 which is not resizeable. (I use 60Hz = SXGA1)

In fact, I would think that 1280x1024 would be *more* desireable than the true panel width, especially when feeding HDTV, since 720p fits pixel accurate and 1080i width is also a relatively nice multiple of 1280 (downscale every 3 pixels to 2).

This is of course ignoring the 6.3% light output decrease by not using those pixels http://www.avsforum.com/ubb/smile.gif

Andy K.
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