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Discussion Starter #1
we all know the teranex is the best video processor out there, but is it a good teammate for digital projectors? Particularly high end ht grade projectors or a more reasonably priced pro grade ones.


given that the teranex products dont scale to most digital projectors native map- would it be advisable to still use one? also the output is hd-sdi. I think the christie digitals can accept this- anyone know of others? would you recommend a tereanex to compliment a digital projector? why or why not?
 

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We will have a teranex for an inshowroom demo if you are interested. This will take place in December and will be announced once we nail down all the details.


The person to date who has installed and used the teranex more than anyone is Chris Stephens. He has used it with the 3 chip dlp as well as crt.

According to Chris there is no need to scale a 1:1 pixel map to benefit from the teranex. Even if you have a digital projector without HDSDI you can use a HDSDI to analog rgb convertor and still gain from it.


I will point this thread in his direction and hopefully he can give some insight.


In the mean time you may want to take a look at this thread. You may find the answer to your questions here.
http://www.avsforum.com/avs-vb/showt...8&pagenumber=1
 

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Discussion Starter #3
Alan,

thanks for your help. I had forgotten about the thread over in the Special Guests forum. I havent had a lot of time to read all the threads lately but I took some time to read the entire thread over there and Chris and others basically answered my questions.


Thats a good point about options if one doesnt have the hd-sdi input. But you know what- Id rather spend the extra money and get the projector with it. I was a CRT person but I was convinced of the relative merits of the digitals b/c the higher end units do look very good and they give you a "big and bright" image. I didnt mind the less than ink black blacks.


I did fire off an email to you about the schedule for a demo. Its a little bit of a trip for me, but I am more than casually curious.


- Jerry
 

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I have experience with this subject. I have been hooking up the Teranex to digital imager projectors for 2 years.


YES it would be wonderful if ANY device could connect directly to the micromirror device (DLP chip) and drive it directly, HOWEVER.


TI has a scaler engine connected to that chip. Your never truly getting past that chip irrespective of what you do on input. I feel the more pixels you give it on input the more accurate the output pixels end up being. IMHO.


This whole concept of driving the DLP at the exact pixel array size is like saying I have to have gray scale at 6500 + /- 1 degree. If you focus only on grayscale and ignore everything else your gonna have a pretty boring grey picture. But it will be very accurately grey.


The Teranex does SO MANY other things right.


Some projectors, and many new ones like the NEC 5000 and 6000 can take 1080P24 directly. REAL D-CINEMA, just like the new theater systems do. I am attending the SMPTE conference Here this week and on Wednesday a paper is being delivered by Jeb Deam of Teranex on scaling to 1080P24 for D-Cinema use. This is a VERY important format. This is the future format for all high end projector formats. Because HD-SDI is the defacto standard in hi end post and broadcast this input standard will be a major focus for hi end display projectors.


D-Cinema, SMPTE is forging the future of Hi Resolution display NOW. The standards in use and proposed use HD-SDI 1080P24 and a DLP device that's 1280x1024. George Lucas shot the upcoming Starwars flick in 1080P24 and even some 720P24 and 60. The post production work was done on a 1280x1024 DLP. When it will be shown it will be 1080P24 HD-SDI displayed on a 1280x1024 device.


The people forging these standards are serious people. I have attended these committee meetings (DC24) and the issue of mapping to pixels has never come up. Its just pretty much a non issue. ALSO these guys are Cinematographers and directors of photography.


The other standards also are NOT compatible with any common standard. 2Kp24 and 2k and 4k.


I donno there seems to be a kinda odd over fascination with this subject I just simple don't understand.


I have hooked up the teranex to many digi in projectors and the picture is stunning for a whole host of reasons other then 1280x1024 / 1920x1080.


I will be at the demo Alan is planning.


I would like someone to explain what exactly is so "wrong" with driving a 1280x1024 with 1080P24 or 720P60 ?. I would like to hash this whole thing out in this thread. My direct experience does not match the view that the pixels from the source must match the pixels of the display device or just try another scalar.
 

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Discussion Starter #5
Chris,

first off- Id like to say thank you and the people from Teranex for being so involved with this forum. I learned a ton just by reading the thread in the special guest area.


Like you, I'd like to hear with someone with your level of knowledge/ experience on why pixel mapping is so important- if that is the case.

As a HT enthusiast, I have enough knowledge to understand what everyone is talking about, but I don't have the practical real world experience you have. Many people here have posted that they get the best results with the digital projectors when they dial in an exact pixel match for their projector (often with a htpc). So thats why I was fixated on that. I had never considered -until yesterday- what you are saying about standards.


Im glad you put this in perspective. Im also hoping to attend the AVS demo- it seems like the trip will be well worth it. It would be great to meet you and see what the Teranex can do. Id really like to see it do 1080p/24 on a capable digital projector.


As of now the setup Id like to go with is the Christie S3 + someones video processor. Perhaps it will be a teranex?............ :)


Again, thank you for taking so much time to explain what the true high-end is up to.



- Jerry
 

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Chris,


I'll have a stab at starting the ball rolling at least!


I don't believe there is any problem with applying 1080P or whatever to a 1280x1024 panel projector by a digital connection.


The problem comes with an analog connection, where, after the Digital to Analog conversion in the source the signal is not adequatley filtered (e.g. most PC graphics cards) and where the display has not been set to sample dead on the original pixels - Then you get the moire effect.


However I've recently been playing around with a Barco D-Cinestar D-Cinema projector. As I'm sure you know, on this unit (and I believe all the D-Cinema units) it's possible to select either to compress the 1920x1080 to the 1280x1024 panel, or to map a 1280x1024 section of the 1920x1080 'directly' to the panel. comparing the two settings, the difference in apparent sharpness is significant (note that this is using a 'native' 1920x1080 source - TI's own Qubit server loaded with the proper files).

Having said all this though, 1920x1080 compressed to 1280x1024 is the way the industry is going and I personally don't have a problem with that!


I hope this is of interest,


Richard Ansell MBKS


Snell & Wilcox
 

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Quote:
Originally posted by RichardA
Chris,



Having said all this though, 1920x1080 compressed to 1280x1024 is the way the industry is going and I personally don't have a problem with that!

Snell & Wilcox
I have a big problem with that. It's outright

stupid to use the current hardware standard of

TI's DLP chips to nail a projection standard that has not even full HDTV resolution, an aspect ratio not compatible with any production standards and an image that's either not sharp when projected on a big screen or full of visible jaggies/pixels,

especially for 2.35:1 material. We need a digital

system with 35mm negative resolution, not so so

release print resolution with digital artifacts

all over the place.

Michel Hafner
 

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Hi,


1920x1080 down to 1280x1024 -- Downconversion often does sharpen the image. You notice the effect with a digital camera photo or a scanned photo: You resize it down to half its original size, and it looks sharper too. I don't have anything to dispute that. Of course, if you then blow up the smaller image size back to the larger image size, it will look worse than the original. (Just as you said -- displaying 1280x1024 portion inside a 1920x1080 image to the same screen surface area as 1920x1080 compressed down to 1280x1024)


However, when upconverting, 1:1 pixel mapping is more important. It has been proven many times with a DILA projector connected to various scalers or a HTPC.


TeraNex does so many amazing things to the image, that 1:1 pixel mapping does almost becomes a moot point. But it's still an incremental improvement; TeraNex should theoretically completely blow away a digital projectors' internal scaler anyway.


Doing 1:1 pixel mapping and not doing it -- there's often still a difference especially if you bring up the AVIA resolution pattern as a test. Depending on the source, the digital display and the scaler, it can be subtle, other times more dramatic, but it's there for many of us picky videophiles!
 

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First...


I am in NYC at the SMPTE conference. I was out late with dinners. I then went and aligned a Marquee of a customer here in new york. Its now 2:40am and I must get up and do it again in 4 hours.


SoooOOoooo..


Im not gonna really chime in yet.


Richard:


Interesting to see that your working with a D-Cinema projector at S&W :)


Teranex is doing alot of that as well :)


Is Nigel Seth-Smith still there ?. He is a very good guy. I like Nigel.


I have very good points i want to share about whats been brought up so far but im DEAD tired.


So I will post more tomorrow. This may allow more views to get posted as well.
 

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Chris,


Yes, NSS is still here (in fact I can see him from here)!

The D-Cinema unit is not at S&W, I've just had a chance to play with it, that's all.


Mark,


You are referring to Analog connection between the HTPC/Scaler and D-ILA aren't you? If so, that's where the problem lies - in the resampling - not in the scaling per se.

Don't forget the problem here is - Does the projector show a better picture without re-scaling the image or with re-scaling of the image - it has very little, if anything, to do with any prior scaling in an HTPC, Scaler or whatever (that is a whole different discussion!)


Richard Ansell
 

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Quote:
Originally posted by Mark Rejhon
Hi,


1920x1080 down to 1280x1024 -- Downconversion often does sharpen the image. You notice the effect with a digital camera photo or a scanned photo: You resize it down to half its original size, and it looks sharper too. I don't have anything to dispute that. Of course, if you then blow up the smaller image size back to the larger image size, it will look worse than the original. (Just as you said -- displaying 1280x1024 portion inside a 1920x1080 image to the same screen surface area as 1920x1080 compressed down to 1280x1024)

When you sit in a cinema and watch a screen you do

not sit further away so the image gets smaller and

the cinema does not install a new smaller screen

because someone decided that 1280*1024 is it and not 1920*1080. The pseudo sharpening by downsampling is irrelevant in the cinema context.

The absolute minimum requirement for a digital projection standard expected to last is full HDTV

resolution. Anything below is not progress compared to what we got but short sighted cementing of an interrim hardware dictated solution that will be quickly outdated as soon as

higher resolution chips get available.

MH
 

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>>"You are referring to Analog connection between the HTPC/Scaler and D-ILA aren't you? If so, that's where the problem lies - in the resampling - not in the scaling per se."


Yes, I'm referring to the analog connection.


It does depend -- sometimes it does not make a significant difference, depending on how the scaler does it.


If the resolution is really filtered (i.e. softened) horizontally in a manner so that the upconverted signal is more truly "analog" where there is no clear 1:1 pixel mapping, then it's more likely more flexible to variances in final A/D conversion (within the digital display) and 1:1 pixel matching is less important here.


For relatively unfiltered scalers that use fully clearly defined pixels horizontally (especially HTPC's and many PC-appliance based scalers like those I currently work with) it becomes very important to have 1:1 pixel mapping (dotclock matching between scaler output and digital display's native rate). In this latter case, there is more control over the final appearance of individual pixels when D/A (scaler output) and A/D (digital display) are much more perfectly matched. The results can look better or worse, since the burden is now potentially nearly fully on the scaler on the final appearance of each single pixel, depending on how good the scaler deals with these individual pixels (interpolation, deinterlacing, etc). There is, of course, the additional overhead of requiring the end-user to calibrate the scaler/projector to run with as flawless 1:1 pixel mapping as possible via tracking/phase/dotclock adjustments on the display itself, or via timings adjustments on the scaler/HTPC itself. But the results can be well worth it for power-tweakers like many of those found on AVSFORUM!


Of course, this more applies to 720x480p being upconverted -- since the benefits of 1:1 pixel mapping is far more noticeable during downconversion than during upconversion than downconversion (as in 1920x1080p down to 1280x1024p) ....


Of course, 1:1 pixel mapping on digital displays really only shows noticeable benefit for scalers with unfiltered or relatively unfiltered outputs (ie, scalers that output really clearly-defined pixels that don't blend gradually into horizontally adjacent pixels. So that's easy to A/D back to digital within the digital display electronics without moire artifacts) .... I'm talking about pixels at the destination resolution level (output resolution).


When I use the terminology "filter", I specifically mean how well-defined each output pixel is. Unfiltered would mean clearly defined pixels that has little analog blend between them. Filtered would mean lots of analog blending between horizontally adjacent pixels. PC computers, for example, typically use very unfiltered output (or comparatively minor filters, that often-picky videophiles sometimes still remove anyway) because graphics card makers want each computer pixel to be as razor sharp as possible. Now in the scaler market, that isn't always good (unless, obviously, you're outputting to a digital display AND you do very good scaling/deinterlace algorithms). Just need to make sure my use of the word "filter" is not confused for other terminology. Basically, when I say "unfiltered" here in this particular message - it means minimum analog blending between horizontally adjacent pixels in the output resolution. (Just making sure that techy types here doesn't confuse this with other types of filters like digital noise filters, digital sharpness filters, 3D comb filters, etc.)


Picture quality goes in this order, when we are dealing with digital displays.


1. Best: 1:1 pixel mapping, unfiltered output

2. Middle: 1:1 pixel mapping, filtered output

3. Middle: No 1:1 pixel mapping, filtered output

4. Worst: No 1:1 pixel mapping, unfiltered output


This is assuming same digital deinterlacing/scaling algorithms are being used in all cases, and the bandwidth of the scalers is high enough for good 1:1 pixel mapping at the specified output resolution. Also, of course, that the algorithms are at least halfway decent: Scaling algorithms that aren't worse than the horizontal interpolation advantage provided by filtering.


Those older scalers with bad scaling, it's possible that the filter provides better "interpolation" than the bad scaling in the old scalers. However, many new scalers provide scaling interpolation that can be superior to the horizontal interpolation caused by analog filtering.


When dealing with scalers with output that's unfiltered, you may see quite a dramatic difference when 1:1 pixel mapping is achieved, especially if you sit very close to the screen.


That's why it's not generally recommended to use an unfiltered scaler with a digital display (aliasing, for example!) - UNLESS 1:1 pixel mapping is achived AND the scaling/deinterlacing is good. Then it can yield superior results.


On the other hand, when dealing with scalers with output that's filtered, the picture quality difference is not quite as dramatic.


For plug-and-play (not needing to worry about horizontal resolution), it is often easier to go with a filtered scaler .... Since A/D converters are more forgiving of properly and fully filtered output (one that has a really analog-like output that doesn't appear to have a specific horizontal resolution at all)


Even the most dramatic differences, of course, may not be noticeable to average "Joe User" eyes. But it's most obviously noticeable to many well known videophiles who frequently post in this forum.


Of course, things are different when we are talking about CRT's since there's no such concept of 1:1 pixel mapping on such displays.


Although most experts here likely know, I also need to mention this little point for others who may need to know: Just doing a specific resolution doesn't automatically do 1:1 pixel mapping -- the resolution needs to be native scanrate matched with the digital display. With proper timings, including dotclock and horizontal and vertical retrace intervals, etc.


I believe it's quite possible that the amazing TeraNex scaler will probably be even more amazing inputting native 1365x1024p into a DILA projector (properly calibrated) rather than the already impressive 1920x1080p into the same DILA projector! Since TeraNex seems to have so much control over each individual output pixel, and do quite an awesome amount of processing already on each single output pixel, it would therefore follow (if the TeraNex output filtering is adjustable or can be turned off) that superior results are possible with a TeraNex outputting 1365x1024 with DILA-precise timings versus TeraNex outputting 1920x1080 when it's being connected to a DILA projector (which has a native 1365x1024 resolution).


(1360x1024 or 1368x1024 could theoretically be used, since many graphics chips are designed to output in horizontal resolutions divisible by 8. In this case, there's minor horizontal overscan or underscan, when 1:1 pixel mapping is achieved.)
 
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