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Author Topic: DLP Resolution Question
Mark J. Marshall
Film God

Posts: 3184
From: New Castle, DE, USA
Registered: Aug 2002


 - posted 12-23-2004 04:53 PM      Profile for Mark J. Marshall     Send New Private Message       Edit/Delete Post 
I constantly hear about the DLP projectors and how there are new chips with higher resolutions available now than there were in the beginning. My question is, what is the resolution of the source material? If you have two different resolution chips, do they produce two different resolution digital files? Or do the projectors down/up convert the resolution of the source accordingly? If so, what is the resolution of the source? Is it currently higher than the highest resolution chip?

Sorry, that's like 10 questions. But if someone could speak about that a little bit, that would be awesome.

Thanks.

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Mattias Ohlson
Expert Film Handler

Posts: 180
From: Falun, Sweden
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 - posted 12-23-2004 05:20 PM      Profile for Mattias Ohlson   Email Mattias Ohlson   Send New Private Message       Edit/Delete Post 
I do not know but I will guess for you.
DVDs are 720x480i but are displayed on digital projectors with very different pixel counts and ratios.
There are likely competing formats but only at one or two resolutions.

What you will most likely see in the future is 4096x2160 for 1.85 and less than 2160 for scope. The files will likely all be 4k and the servers will transform on the fly between 4k stored and 2k/4k displayed. All pixels might be used and demand an anamorphic lens to display the correct ratio.

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Lyle Romer
Phenomenal Film Handler

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From: Davie, FL, USA
Registered: May 2002


 - posted 12-23-2004 06:31 PM      Profile for Lyle Romer   Email Lyle Romer   Send New Private Message       Edit/Delete Post 
I'm pretty sure that the current (and likely future) digital projectors use the entire available display resolution and then use an anamorphic lens to get the correct aspect ratio.

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Steve Guttag
We forgot the crackers Gromit!!!

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From: Annapolis, MD
Registered: Dec 1999


 - posted 12-23-2004 07:19 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
I'll qualify this...based on the DLP and Dcinema projectors I've worked with (Barco DP50 and Christie DCP-H).

The projector's native resolution is SXGA or 1280 x 1024, which is a 5:4 ratio (or 1.25 if you must live in decimal land).

The DCinema files sent to those projectors are also 1280 x 1024 but stored and transmitted in a medium that can handle up to 1920 x 1080. The medium, HDSDI, handles 720p, 1080i, 1080p just fine in several frame rates.

In an interesting situation...the AFI/Silver uses the Barco DP50 projectors. The facility is entirely wired for HDSDI to handle HDTV, among other things. When the first "Dcinema" "film" they have played there (just recently) was sent over the system...it looked pretty awful at first. When the system is told to display an HDSDI 1080 signal, the presumption is that it is indeed 1920 x 1080. However, that is not how the feature was formatted. To save space and load time, only 1280 x 1024 information was stored on the video server (Qvis Qbit). So...when things were first fired up, the picture was displayed as encoded...like a little squarish picture.

The projectors are rather sophisticated...one could tell the DP50 to blow up the picture to fill the screen and it would do so...however that would not yield as good a picture as one could have. Since the projector is only an SXGA projector, the system squashes the 1920 x 1080 signal to fit the projector...thus a smaller initial picture would also get shrunk down and loose information. Instead, the video server was given a direct path to the projectors (there are three theatres at the AFI/Silver and any video player/server can feed any or all projectors). Thus, the 1280x1024 information was transfered 1:1, you might say. This resulted a picture that represents the native resolution of the projector. Since the film was shot Techniscope (2.35:1)...a 1.9X anamorphic lens is used on the output of the projector to finish the job (approx ratio of 2.375:1).

So as far as the 2K projectors...all of the infratstructure should handle the 2K stuff just fine...that is native for HDSDI running 24p or 30p.

I would hope, now that 2K projectors are out there that in the future 2K versions of the "films" would be available to avoid scaling.

As for the 4K machines...I have no experience with them but I would suspect they are going to have to use some propritary method of moving the video. One is talking about a lot of bandwidth that will be needed.

I don't see the leap to 4K happening all that quickly. Heck 2K hasn't really made any significant inroads...even the 1K systems are a bit of a cinema novelty right now.

Personally, I think 2K is a good starting point for DCinema since I never liked the whole SXGA format for movies...it just what was available at the time...not really a good reason to use it.

Steve

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Ian Price
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From: Denver, CO
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 - posted 12-23-2004 07:33 PM      Profile for Ian Price   Email Ian Price   Send New Private Message       Edit/Delete Post 
TI seems to have six DLP Chips for sale at the moment.

480P or VGA 600x480 NTSC
576P PAL
HD2 1280x720
0.55 SVGA 800x600
0.7 XGA 1024x768
0.9 SXGA 1280x1024
SXGA+ 1400x1060

This is all I could find from the TI site. I know that they have another resolution beyond that.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12084
From: Annapolis, MD
Registered: Dec 1999


 - posted 12-23-2004 08:57 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Ian,

The 1280 x 1024 chip set as used by the DCinema projectors are discontinued. The 1080 x 2048 (I may be wrong on the 2048 part by a few pixels...it is in the 2048 range though) chip set (aka 2K) is what are in the current 2K machines. These machines run up to 1.85:1 without any anamorphic lenses...the anamorphic lens is only used for scope (just like film). However, the DCinema projector uses an anamorphic that has less expansion and is closer to 1.25X rather than film's 2X or even the 1.2K projector's 1.9X

Steve

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Mattias Ohlson
Expert Film Handler

Posts: 180
From: Falun, Sweden
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 - posted 12-24-2004 06:02 AM      Profile for Mattias Ohlson   Email Mattias Ohlson   Send New Private Message       Edit/Delete Post 
My feeling is that where digital cinema will really start is 2k. The resolution is not that expensive. You pay more for a brighter projector.
Expect
2048x1080 as is or
2048x1080 scope date squeezed in +1.25 lens expansion
I am sure they will have provisions for installations without the extra lens.

I have wondered what they are going to use for 4k since 2k somethimes needs 2x hd-sdi coupled as a pair.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12084
From: Annapolis, MD
Registered: Dec 1999


 - posted 12-24-2004 08:02 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Where are you getting your information from?

The cost of brighter is near zero...the cost of increasing resolution is phenominal. In the DCinema world...there are only a couple of projectors...the brighness is determined by lamp size. Whenever TI does a revision to the DLP...it is upwards of $100million. Think about the Return on Investment on that one...that is THE reason I feel they have no or little interest in going beyond 2K. They have now made the technology that can migrate into the home market, which is not likely to move beyond 2K for some time.

As to 2K using more than 1 HDSDI line...I have not seen that and it makes no sense to me.

Steve

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Michael Schaffer
"Where is the
Boardwalk Hotel?"

Posts: 4143
From: Boston, MA
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 - posted 12-24-2004 08:17 AM      Profile for Michael Schaffer   Author's Homepage   Email Michael Schaffer   Send New Private Message       Edit/Delete Post 
Steve: In the above example, I understand the 1280 x 1024 image was letterboxed in the 1920 x 1080 signal and would therefore lose a lot of resolution when the whole 1920 frame would be shrunk to fit the physical resolution of the DP50. However, couldn't you have simply selected 1280 x 1024 as the active area in the DP50 setup? Then it would only look at the selected area inside the signal and try to fit it on the chip (which in this case obviously wouldn't actually lead to any resizing).

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Darren Briggs
Master Film Handler

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From: York, UK
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 - posted 12-24-2004 08:50 AM      Profile for Darren Briggs   Author's Homepage   Email Darren Briggs   Send New Private Message       Edit/Delete Post 
2K D-cinema resolution is 2048 x 1080 pixels.

To get the best use of resolution available is to use a 1.25 anamorph on the projector to get 2.4:1 Scope ratio.

But the most practical way in the comercial cinema environment is to scale the images onto the chip, all ratios using a common height.
i.e 1.85:1 is placed in the center of the chip with black bars top bottom and sides and scope uses the full width of the chip but letterboxed onto the chip with un used pixels top and bottom if you see what i mean!

The eye can see horizontal resolution better than vertical resolution, so loosing some defintion top and bottom is hardly noticed at all. But you are using the fill 2048 width and without the problems anamorphics add. Giving a sharp and bright image.

Therfore once the projector is set up the ratios are selected electronicly along with all the source files etc.
Currently it seems everyone is using different colour space's so each new film tends to have to have new files set up to beable to screen the film correctly.

Then theres the issue of using alternative content through the projector that opens up a huge can of worms!
But as for full 2K D cinema the above is the best way we have found to use the format.

Also 1920 x 1080 is not true 2K resolution and is still classed as HD. Films may be show on 2K machines but are not true 2K with a 1270 or 1920 source, a bit like classing 35-70mm blow up as true 70mm.
1.3K or any resolution can be re-scalled (blown-up!)onto the 2K machines.

2K projectors have 12bit colour (currently restricted at this as the TI formater boards can only hanle 12bit)where as 1.3k are only 10 bit.
(1.3k 10bit is from memory but think it is correct!)

So the colour is far superior on 2K projectors.
Be aware not all D cinema servers can supply the 12bit colour depth!

All very confusing!

Darren

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Mattias Ohlson
Expert Film Handler

Posts: 180
From: Falun, Sweden
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 - posted 12-24-2004 09:51 AM      Profile for Mattias Ohlson   Email Mattias Ohlson   Send New Private Message       Edit/Delete Post 
Darren
1 Are you talking about taking 10 or 12 bits on the input? TI always claim 15 bits but perhaps that is after dithering. Thus source to 2k would be 12 bit and displayed 15bit?

2 Do you expect movies to be delivered at 2048x1080 1:1 squeezed so that the 1.25 lens lets you project Cinemascope with the highest resolution possible? That would make sense since people already do this in home theater setups. (not at that resolution though)
3 Since you talk about scaling the source on the chip for simplicity are automatic masking systems expensive?

I was guessing that a DP IS-8 is quite alot cheaper than a Barco DP100. I understand that brightness can be chosen over a wide range with Barco DP100 and that extra brightness here only is a marginal cost. I expected you could save money by limiting your lumens demand by choosing an IS-8. That makes sense if you have a smaller screen.

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Darren Briggs
Master Film Handler

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From: York, UK
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 - posted 12-24-2004 10:29 AM      Profile for Darren Briggs   Author's Homepage   Email Darren Briggs   Send New Private Message       Edit/Delete Post 
Hi Mattias,
Point 1, I was informed by a server manufacturer that the formater can only take in 12bit, so 15 bit may well be after its dithering.
Point 2, I would expect as you said that movies wont be letterboxed on encoding as it is always best to have the highest quality on the server, and then by loosing resolution and scaling it dwon on the chip you are in effect scaling the data and compressing it down. Its alot harder to scale upwards without artifacts.

Point 3, All manufactures have turrets for anamorphic lens placement infront of the prime lens, these could be controled remotly by the server as and when required. But the cost of an Anamorph, then the lens turret add alot of money to the instalation.

The DP IS-8 is a very good machine, and as the name says it is capable of screen sizes up to 8 meters.
Have used one on a small screen and have used the IS-15 many times. Both good projectors and are fairly portable. The IS-8 is ideal for portablity.
The images both machine produce are very bright indeed. Im sure the IS-8 could even be used on slightly larger screens than 8 meters.
We have used the IS-10 on 12 meter wide screens and it look great, and thats just a 1.3K machine. The Barco DP30 the IS-10 equivlent is not as bright bar far, the DP light engine seem more efficent. Even used the IS-10 ooutdoor at the 2004 Cambridge film Festival on a 15meter by 10 meter high screen. No Anamorphis lens whcih gave us maximum light output and look equally as bright as our 35mm machine with a 3K xenon.

Darren

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12084
From: Annapolis, MD
Registered: Dec 1999


 - posted 12-24-2004 11:24 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
quote: Michael Schaffer
However, couldn't you have simply selected 1280 x 1024 as the active area in the DP50 setup? Then it would only look at the selected area inside the signal and try to fit it on the chip (which in this case obviously wouldn't actually lead to any resizing).
No, the normal HDSDI lines in the facility presume 1920 x 1080 so before it ever made it to the projector the effective resolution was lowered. Remember, the AFI/Silver runs "altenative content" much more than DCinema features. Much of their content originates in the broadcast world.

Thus, the HDSDI lines were also given a direct feed into the DP50 so, as you say, just the 1280 x 1024 portion of the image could grabbed as per DCinema convention. Had the image been stored on the server as a 1920 x 1080 image (maximum width) then it would have worked the other way.

quote:
the most practical way in the comercial cinema environment is to scale the images onto the chip, all ratios using a common height.
i.e 1.85:1 is placed in the center of the chip with black bars top bottom and sides and scope uses the full width of the chip but letterboxed onto the chip with un used pixels top and bottom if you see what i mean!

I don't think I entirely see what you mean.

Why would you letter box 1.85? 1998 x 1080 will entirely fit within the DCinema chip set (2048 x 1080) thus there will be maximum resolution.

For "Scope" again fill the height and now fill or nearly fill the width and use the 1.25 anamorphic lens to again use maximum number of pixels and use the most data doing it.

As far as color space goes...that really needs to settle out and fast. This business of everyon'e favorite reminds me of the mag days when the various sounding facilities EQed their system to their own liking and never allow a common reference test film as existed for optical.

Steve

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Michael Schaffer
"Where is the
Boardwalk Hotel?"

Posts: 4143
From: Boston, MA
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 - posted 12-25-2004 05:27 AM      Profile for Michael Schaffer   Author's Homepage   Email Michael Schaffer   Send New Private Message       Edit/Delete Post 
Tell me what I don't get here (sorry, I am just a little slow in the head): If the signal transported over the HDSDI lines is 1920 x 1080, wouldn't the 1280 x 1024 image simply be letterboxed inside that frame (basically with 640 x 56 lines blackened). If fed into the DP50, it would indeed try to shrink the image to fit on the chip, and since it doesn't know what is image and what is letterboxing, the actual image would be shrunk and image information/resolution be lost. OK. But if you define 1280 x 1024 only as "active area" in the setup, then the DP50 would just look at that portion of the image (the active area might have to be offset though to "catch" the frame if not perfectly centered in the 1920 x 1080 signal), and not find any need to shrink it since it fits the physical resolution of the chip perfectly.
Reason I am asking is, we have done a lot of alternative content on our DP50s, and even though they are also set up for movies in 1920 x 1080 (which in reality happens rarely though), we haven't had any alternative content so far which required downsizing from a larger input signal than the physical resolution. I played massively with alternative content in lower resolutions and formatting solutions for these, but so far never with actually bigger input resolutions.

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Darren Briggs
Master Film Handler

Posts: 371
From: York, UK
Registered: Dec 2001


 - posted 12-25-2004 06:18 PM      Profile for Darren Briggs   Author's Homepage   Email Darren Briggs   Send New Private Message       Edit/Delete Post 
Scaling images is not a straight forward thing.
You can tell the TI head what input resolution you are feeding it , then plot it anywhere on the chip, i.e you can take a 1.3k anamorpic image input and scale it up on a 2k proj to screen it without an anamorph for example.
I have used Barco, Christie and DP media switcher to scale alternative content, But your media sweitcher will be set to output one image resolution, i.e set to a 1.3k output for a 1.3k projector. The projector is then set up to the media switcher and only one screen/source file is used for the alternative content, all other image scalling, shifting etc can be done in the switcher.

Steve, what i said
quote:
--------------------------------------------------------------------------------
the most practical way in the comercial cinema environment is to scale the images onto the chip, all ratios using a common height.
i.e 1.85:1 is placed in the center of the chip with black bars top bottom and sides and scope uses the full width of the chip but letterboxed onto the chip with un used pixels top and bottom if you see what i mean!
--------------------------------------------------------------------------------

Meaning the 1.85:1 image would be scaled down to fit on the chip, if using the full width, you then have to have anamrorph for Scope, and not having a common height etc.
The use of a anamorph adds cost and then you have to have a turret for the anamporph etc adding to the operational hassle of the system.
I have used this principle lots and image quality is not compromised at all. Yes you are never using the full height of the chip but as mentioned previously your brain is more critical on horizontal resolution rather than vertical.

We mastered all of our content at 1920 resolution, this is the best compromise for compatability as it is high quality for 2k and can be scalled down to 1.3k.

It depends on the situation on how you treat the images and set up the system.

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