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Author
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Topic: Real D & Dolby 3-D - What is the difference?
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Julio Roberto
Jedi Master Film Handler
Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008
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posted 12-14-2008 04:43 PM
quote: Mark J. Marshall
Although most people can't tell the difference because they are unfamiliar with what two images being on the screen in perfect sync look like compared to two images that are not in sync.
Thank TI for the 144hz delay. With home 3D field sequential systems, this temporal disparity is a whooping 1/60th of a second for the "frame" (field) and "nobody complains" ![[Roll Eyes]](rolleyes.gif) .
I can also detect the temporal disparity at 144hz, so no doubts it contributes to "headaches", but it's reasonable and unnoticeable to most people. The practical limit of human perception (for this type of application, not for absolute black/bright white contrast) would be a bit less than 1/200th of second, so it's almost there.
So with 3D DLP digital cinema we have:
-Our eyes being used as a d/a converter to interpret pulses of flickering bright light into shades of color.
-Our brains screwed with by presenting our eyes for 144th of a second with an image that is behind in time from the one in the other eye (never mind an image that is totally different from the other eye everytime there is a scene change in the movie).
-Our eye muscles excersised by providing them with commands to focus in one place and converge in another.
-Reduced brigthness (compared to 2D presentations).
-Reduced resolution on older (by just a few months) TI chipsets (the ones that couldn't hold the full 2K resolution at full 144hz refresh rates).
-Increased compression artifacts/reduced image quality (3D images at 2K 48fps are more compressed by the DCI specification; 0.65MB max per frame compared to 1.3MB per 2K 2D 24fps frame).
-Reduced (halved) color resolution per image. 48fps 2K 3D frames are subsampled 4:2:2 compared to 4:4:4 for a 24fps 4K 2D frame.
-Reduced color depth: 10bits agains 12bits for 2D 2K.
Etc, etc. We won't go into silver screen issues or ghosting (noticeable in some high-contrast scenes), or colometry issues (Dolby).
3-D is a bit "weird" by itself to most people (to the non-3D-fan). It already carries inherent shortcomings such as the focus/convergence eye "excersise" and the "unconfortable" (and not $$ free) 3D glasses.
If the industry starts piling up dissadvantages to 3D presentations on an already not-too-impressive 2K digital system .... well, I wonder if 3D will once again dissapear into a "fad" while execs scratch their heads wondering why it happened.
3D needs to be done "perfect" or "not at all", as even "perfect" 3D has shortcomings and detractors (i.e. customers with eye problems or stereopsis perception issues+nobody really likes wearing stupid glasses, even less if they are not free).
And, as it stands right now, a 3D picture is usually (in a bold, not-100% precise way):
-Of reduced resolution (once resized for common height or common width screen to the appropiate aspect ratio).
-Of 1/2 the amount of chroma resolution and reduced color palette (10 bits 4:2:2 subsampling)
-Of twice the compression (2.35 bits per pixel against 4.71 bits per pixel of 2D 2K 24fps content).
-Of 1/3 the brightness (as low as 3.5fl).
-Presented at different times for each eye (1/144 second apart).
-Screwed colors due to silver screen or Dolby bandpass filters. Perhaps even uneven illumination if we sit at an extreme angle from the center of the screen.
And then, add each format or inherent shortcomings (ghosting, cheap glasses aberrations/dirt/scratches/etc, focus/convergence, higher ticket expense, 10% of customers who don't like 3D).
And you thought that 2D digital cinema was expensive and not too good. Doesn't it start to look good now with 3D being even more expensive and "worse" still? Even my home projector and LCD TV start looking *really* good ...
I don't doubt that it's good enough for most people, but eventually audiences will realize they don't quite enjoy their theater presentations that much when compared to their 60" LED LCD TV at home ... not to mention fast-upcoming technologies for even more breathtaking TV's of huge sizes and affordable prices lined up for the next 2 years.
[ 12-20-2008, 01:22 PM: Message edited by: Julio Roberto ]
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Julio Roberto
Jedi Master Film Handler
Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008
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posted 12-14-2008 07:09 PM
I hope they start "timing" digital 3D movies for that brightness level instead of the 3.5 to 5.5 fl they are "timed" now. Otherwise, instead of an improved image it would actually look worse (washed out) on anything above 5.5fl.
Then again, forcing early theaters with 3.5fl levels to do something about it. More $$$$ to spend on gain screens or "bigger" lamps. There is always the great solution of using two projectors, with the small disadvantage of costing "twice" as much ![[Wink]](wink.gif)
Theater owners must just love digital ![[Smile]](smile.gif)
Probably Avatar 3D will be the first timed for something more suitable like 5 to 7 fl. Which, once again, would look crappy in 3.5 to 4.9 fl theaters ... I don't object strongly to a brighness level of around 6fl, as like it was mentioned here, your eyes adjust after a while to the low light level and produce a reasonable image. But below 5fl is certainly not acceptable in my book.
Oh well. Let's just settle for the Dolby thing on the brightest new-generation projector (for the full frame resolution at 48fps) you can find and a gain screen (although I wouldn't usually go over 1.6 gain depending on the geometry of the theater) and shoot for 6-7fl. Aditionally, dual dual-sdi (as oppossed to current single dual-sdi) frame server would also get rid of the 4:2:2 subsampling for 3D, as it's a limitation of the SDI transport system and not the server, the projector or the DCI specifications. Don't worry, soon Dolby and Doremi will be happy to add another dual-sdi card to your server for a "small" upgrade price.
Now, if Dolby would just make the ![[evil]](graemlins/evil.gif) glasses at an affordable price point ... Certain markets can not tolerate kids stealing/breaking/vandalizing $20 glasses on $5 tickets, of which, of course, >60% goes to distributors/taxes/etc. $10 glasses, maybe, as $1 or $2 can be added to the ticket price to recoupe the losses.
Dolby just found themselves a nice permanent revenue stream. Some 10+ glasses a month to each theater with their system. Nice.
And theater owners just found out another permanent expense attached to the "higher revenue" from 3D movies.
Then again, we have to factor in the savings in digital from splicing tape
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 12-14-2008 08:23 PM
2.2 gain? Yeah Right...please post a PSA chart on that one. I've been working with a Harkness Pearlux140 that has about the worst uniformity I've ever seen. The only way you are going to get uniform brightness on that is to have a pretty intense curve on it and then will likely get a washout from self-illumination.
As to Dolby making a killing on the glasses...nope, not likely...they are expensive to make. Do the cost analysis on a pair at $27.50 each. They are rated for 500 or so uses...factor in the cost of cleaning, some early replacement due to damage and theft and you still come down to something that is pretty cheap per show. Factor in an upcharge for 3D and you stand a much better opportunity to actually make money, at the theatre level, on 3D than with Real-D...whom is your partner...sharing in all revenue, with the studio.
As to Dolby's colorimity...I dunno...once you go digital, you have a funky colorspace...with a chromaticity meter, one can tell if it is a DLP or film projector just by looking at the spectrum....forgetting about the 3D entirely. With Dolby's system, each eye is calibrated independantly for white-point and the three colors...so even with Dolby 3D, the color space is well defined. The Dolby glasses are expensive due to those precise filters that are in them.
Steve
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Julio Roberto
Jedi Master Film Handler
Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008
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posted 12-14-2008 08:51 PM
I thought Dolby had lowered their list price to $19 for the glasses. So you can figure what the profit was when they listed for $28, unless you believe they obtained a manufacturing cost reduction advantage of 30% in a few months.
Regardless, don't think all markets can happily add $2/$3 surcharge for the 3D shows.
Some markets have $5 tickets. The most they can get away with is $1 or $2 at most.
Factor the taxes taken out from that and that sooner rather than later the studios are gonna want their 60% of that surcharge too (many already do).
Factor the additional equipment for the glasses (anti-theft, glasses collection personel, cleaning equipment) and added consumibles (water, cleaning solution, washer electricity, spare parts).
And place yourself in some markets where kids are inherently brats willing to destroy/scratch/burn/graffiti anything they can get their hands on just for the sake of it. And consider most 3D movies are "kids" movies, not responsable adults-geared ones.
And soon you'll see your "added 3D revenues" coming from your (few) 3D films can not justify losing $20 (not counting shipping and other charges) over a $7 ($5+$2 surcharge) ticket of which you only get to keep $3 gross profit if you are lucky. A single lost pair of glasses means you loose all the gross profit from about 7 patrons. Actually, what you do is transfer part of your profits to Dolby and the glasses manufacturer .
I know Infitec filters are not cheap to manufacture. But I also (wildly) estimate the glasses can be made for about $10 at current production levels and as low as $4 once volume picks up.
So Dolby and its partner is making a very nice profit on the glasses, thought not "killer".
On the other side, paper glasses for Real 3D can be made in volumen for under $0.15 and re-useable plastic ones of half-decent quality for under $1.
Just like movie theaters and popcorn/soda sales, 3D has always been a business where the hidden killer profit was the sale of (millions of) glasses.
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 12-16-2008 10:37 AM
Speaking of Journalistic errors...
Okay...the list price in USS for the Dolby glasses is $27.50, not $19.00...if you want to "believe" something...look at the Dolby price sheet.
So lets use list...$27.50...at 500 uses, excluding cleaning and other overhead costs...it costs the theatre 5.5 cents/show for Dolby 3D. Lets say you loose half before 500 shows (and to allow for cleaning and such)...so that doubles to 11-cents/show. Even a modest $1 upcharge will profit the theatre far more, percentage wise than the film itself. In many markets, the upcharge is $2/show...now you are getting into tidy profits. Much more so than with Real-D, who is taking a sizable percentage of the upcharge.
Is Dolby Making a profit? Yeah...whats your point? It isn't like xenon lamp manufacturers are not making a profit selling your stuff that wears out too. Dolby should try to make a profit...otherwise, they will go out of business. Based on the dealer discounts no the glasses...I doubt that the glasses are high-profit items in unit sales...they are not on the same discount structure as the rest of their equipment.
Dolby's recommendation for a gain screen is strictly to get the CENTER screen brightness number up. One needs 5-times the light for 3D (anybody's 3D) as they do for 2D. In short, you need your 2D picture to have the light output of 30-70fL to be in the 3-5fL range for 3D. Note, this only helps you in the center of the screen...you WILL have hot spotting effects. Gain screens require curvatures to focus their light back (which brings about geometric distortions). An ideal screen for Dolby 3D remains matte-white (1.0). You just need the light to do it. I believe the Dolby Screening Room (in San Fran) is a matte white.
7fL means nothing with regards to cross-reflections...there isn't a threshold there. The key is the long radius...odds are, you could curve the screen much more, even out the light and still avoid wash-out.
Regarding the Perlux 220...
The fiction:
quote: Mark Gulbrandsen
uniformity is far better than silver screens of the same size
The reality: Harkness PDF on their screens for 3D
The Harkness Spectral 240 3D (Silver) starts with a 2.4 gain (0-degrees off direct ray)...and drops to 1/2 as much light at about 22-degrees for an "accpetable cone" of light of 44-degrees. The Perlux 220 starts at 2.2 gain at 0-degrees and drops to 1/2 as much light at 24-degrees or about a 48-degree cone...WOW what a difference! Compare that to a Perlux 180...you get a 66-degree cone. A Perlux 140...100-degree cone. A matte-white...effectively a 180-degree cone.
You can't get around the physics of the light...look at your PSA readings..about all you get for a Perlux 220 over a Silver screen is better color...light uniformity still sucks and a radius that is 1.25x Throw is not going to even it out that much though it will move it in the right direction. If your radius was closer to 80% of your throw, you'd get things much more uniform...but one would need to know the throw, screen size, theatre dims and all that to get it optimal...and you'd still likely only cover about 2/3rds of the available seats well. If you are just looking to give that high light reading in the middle, then I guess any high-gain will do...shoot, put in a mirror! It will get a VERY high light reading...in one spot.
Steve
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Julio Roberto
Jedi Master Film Handler
Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008
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posted 12-16-2008 12:19 PM
Yeap. US list $27.50 for Dolby 3D glasses indeed. Down from $39 a couple of months back. My mistake.
Even more to the point, though
Don't forget that the $1/$2 upcharge has also to be shared between the studio (say 50-60%) and the goverment (say 5-17% tax). Then we factor in cleaning expenses. All of the sudden, your estimate of worse case scenario (and I believe it can even worse than that, but half the estimated life is a generous assumption) of 0.11 cents per show start to approximate the surcharge gross "profit" ($1-17%-60%=$0.23 ... add cleaning and equipment cost, there ... your 3D "extra gross profits" are gone).
And no, I don't second guess your estimate as to how much it may cost Dolby to have the glasses manufactured. Your guess is as good as mine. Mine is under $10/pair at current levels, but of course I don't know what I'm talking about since I've never made 3D glasses (well, I've made a few millions, but they were not multi frequency bandpass filters and that's beyond the point anyway) so it could be way off, I admit. It may indeed be close to $20 (after dealer discount and Dolby's profit) if you choose to favour that figure. Or we both may be way off and it's close to $5. I wouldn't be surprised at all.
And I agree with all your points about gain screens. It's generally tough to get something above say 1.3 to fully work to your advantage w/o shortcomings. Not to mention something about 1.6 or so. Of course, it all depends on the architecture of the theater (angle and distance of the booth to the center of the screen, length vs width of the auditorium, seating placement, screen curvature/aligment, etc, etc).
But a very high (above 2.0) gain screen is usually going to bring some nasty issues to the table indeed. Not necessarily, but usually will.
[ 12-16-2008, 01:52 PM: Message edited by: Julio Roberto ]
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Julio Roberto
Jedi Master Film Handler
Posts: 938
From: Madrid, Madrid, Spain
Registered: Oct 2008
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posted 12-16-2008 01:25 PM
Yes, that's what I meant. Perhaps I didn't make myself clear.
What I meant is that factoring they will only last half their rated cycles, due to loss/breakage/scratching/etc is a "generous" example of a worse case scenario. One would normally expect not to lose that many (50%) of the glasses before their effective life is over.
So although I do believe in some markets the "loss" rate can be even worse than that, I don't object at all to using half the rated life as an example of worse case scenario. I know glasses not vandalized will probably outlast their full rated life as well.
Again, I'm not saying that Dolby is making an absurd "killing" on the 3D glasses or that most theaters are going to be losing kazillions on 3D shows.
I'm saying that part of your extra 3D profits are going to go to a deserving partner: your glasses supplier
And I'm saying that if Dolby glasses retailed for far cheaper, their only disadvantage as a 3D system that can be recommended to everyone would dissapear.
My only theatrical customer just refuses to hand out $28 glasses to 12 year old kids that paid $6 (out of which he gets less than $3) to get in. Because he knows that, at 23 cents extra profit from the surcharge, he is gonna have to hand out that pair of glasses over 120 times (to also cover washing, etc) to 120 kids before he can pay that pair off and even dream to start making a profit.
And he doesn't believe the glasses will survive that much.
I don't agree with him, but I also don't blame his distrust with the glasses being such an expensive item.
Now, if the glasses were something like say $15, then it's much easier to reason it. And at something like $10, they will totally own the 3D theatrical market.
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