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What are the 3D cinema and blu-ray standards?


I would like to know what the 3D cinema standards and tolerances are for nominal projector, review room, theatrical presentations. The white level, luminance uniformity, sequential contrast, intra-scene contrast, gamma. Also the standards for monitors used in mastering the new 3D blu-rays for the home, and recommended home display brightness.



For 2D digital cinema

Digital Cinema Initiatives, LLC, Digital Cinema System Specification Version 1.2 March 07, 2008

Nominal Projected Image

ambient light level projector off 0.01cd/m2 (0.0029ftL)

white luminance 48cd/m2 (14ftL)

luminance uniformity 85% of center

minimum sequential contrast 2000:1

minimum intra-frame contrast 150:1

transfer function down to 5% peak white. 2.6

color accuracy match

Review Room

ambient light level projector off 0.01cd/m2 (0.0029ftL)

white luminance 45.6-50.4cd/m2 (13.3-14.7ftL)

luminance uniformity 80-90% of center

minimum sequential contrast 1500:1

minimum intra-frame contrast 100:1

transfer function down to 5% peak white 2.6 +/-2%

color accuracy +/-4 delta E

Theatrical Presentation

ambient light level projector off 0.03cd/m2 (0.01ftL)

white luminance 37.8-58.2cd/m2 (11-17ftL)

luminance uniformity 70-90% of center )

minimum sequential contrast 1200:1

minimum intra-frame contrast 100:1

transfer function down to 5% peak white 2.6 +/-5%

color accuracy +/-4 delta E


Ideal viewing distance 1.5-2x screen height, maximum viewing distance 3.5x screen height


I am uncertain if the white luminance above is for peak white or reference white, as term peak white seems to be used occasionally when referring to reference white. I have read conflicting information that DCI has a peak white of 15.28ftL and a reference white of 14ftL. Could someone clarify this for me?

According to the UK Film Council Digital Screening Network content projected in Rec.709 colour space is assumed to have been mastered for a display gamma of 2.45. So projecting blu-rays should be at gamma 2.45.



For film print cinema

What I have read elsewhere on the web so may not be reliable.

I have read traditional 35mm color film print 400:1, sequential 1600:1 pre 1997, 4000:1 from 1997. With film print in theory capable of 10,000:1 but in practice limited by the dynamic range of the negative and further reduced by projection flare. Resulting in a projected sequential contrast ratio of about 3000:1 and intra-scene contrast of about 500:1. SMPTE 196M minimum on screen contrast ratio 400:1. Typical theaters around 2000:1 - 1,000:1 with intra-scene contrast as low as 150:1 - 100:1. Do these figures sound about right?


Gamma is s-curved with the center being about gamma 3.0


Assuming a film transmissivity of 87%, the SMPTE 196M specified 55cd/m2 (+/-7cd/m2) 16ftL (14-18ftL) for professional screening rooms equates to approximately 14 ftL from a film projector running with clear (D-min) film. SMPTE 196M states that commercial cinemas must provide 12 ftL to 22 ftL at the center of the screen measured from viewers location, with luminance uniformity 75-90% and the edges of the screen measuring at least 10ftL. Room reflected light should not exceed 0.25%. ITU standard is 10ftL to 14ftL with luminance uniformity of at least 75%.


Kodak document on scope and flat apertures states "Typically, a projector set up to produce the SMPTE standard 16 footlamberts screen luminance for the 2.39:1 aspect ratio "scope" format will have only about 13.4 footlamberts for the 1.85:1 "flat" format, even though the "scope" screen image is wider"

"The introduction of CinemaScope by 20th Century Fox in 1953 remains one of the most significant engineering achievements in motion picture technology. The technical triumph of the "scope" format is its elegant simplicity. The anamorphic lens allows the use of the maximum image area on the film, and puts it on the screen. A larger image area gives pictures that are brighter, sharper, steadier, and less grainy. In contrast, the current 1.85:1 "flat" format evolved simply by cropping the available film image area and projecting it at greater magnification to produce a widescreen picture, at the expense of both light and image, and a waste of available film area on the print."


Lucasfilm Theatre Alignment Program (TAP) showed the average screen luminance in first-run theatres to be about 11ftL center. Just under half of all complaints to a phone THX hotline were that the image was slightly too dark, with the next most common complaint being the image was extremely dark. Buena Vista survey of thousands of screens reported in 1997 to have found an average of 8-9ftL center. Kodak operation big screen survey of first run theaters in the same year found an average of 6-8ftL center. According to Kodak even at 12-13ftL the image in medium and dark scenes lacks detail due to insufficient brightness.


I am somewhat uncertain about white being 14ftL as I have read elsewhere that the 16ftL open-gate figure translates to 12ftL with film running.


SMPTE 196M color temperature 5400K +/-200K


SMPTE recommends the screen occupies at least 30 degrees of the viewers field of view.


Viewing distance, 1953 research by 20th Century Fox when developing cinemascope 2.35:1 determined screen should occupy 45 degrees of viewers field of view. Due to film granularity, jump and weave becoming problematic closer.


THX

Center of screen 16ftL +/-2ftL, 5% in from the edge no less than 75% and not more than 85% of that at the center. No part of the screen should be less than 10ftL

Center resolution 68 lines/mm or more, side resolution 56 lines/mm or more, corner resolution 40 lines/mm or more.

Maximum viewing distance, screen occupies at least 26 degree, recommended 36 degrees from most distant seat



The only 3D cinema standard I have read is some reference to mastering at 4.5ftL white, with 4ftL being acceptable at the cinema.


2D mastering for home viewing

Greyscale color D65

EBU-TECH 3320 User requirements for video monitors in television production

Grade 1 master monitors reference white of 70–100cd/m² (20–30ftL). Sequential contrast of at least 1000:1, intra-scene contrast of at least 200:1. Gamma 2.35 for PAL checked for robustness at 2.2 - 2.5.

Read elsewhere on the web

Refrence white level might be 80cd/m² (23.35ftL) like with sRGB

Mastering gamma for NTSC 2.22 but checked for robustness.


2D viewing in the home

EBU-TECH 3321 EBU guidelines for consumer flat panel displays.

Gamma 2.35 for PAL

PAL 50" diagonal flat screen display peak white recommendation is capable of at least 200cd/m² (60ftL)

Read elsewhere on web

reference white of 23ftL for PAL


SMPTE RP166 Reference white for TV of 35ftL in dim surroundings with ambient light level
 

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If you are serious about obtaining authoritative and accurate information regarding these issues, I suggest you consult the usual motion imaging industry standards bodies: SMPTE, ITU, EBU, ISO, etc. You rarely say where you "have read" such information in your post. If it has been in a forum discussion, look for references to supporting documentation from an authoritative source. Otherwise, don't rely on it as being correct. There is no shortage of individual, anecdotal perceptions and assumptions, and/or personal preference, vague recollections, guessing, inappropriate applications, illogical conclusions, confident but misbegotten declarations and assertions, etc., in forums and news articles. There has been a continuing flow of articles in recent months pertaining to the development of 3D for cinema and home in SMPTE's 'Motion Imaging Journal.' If you are not already a member, you would benefit from joining.


Best regards and beautiful pictures,

G. Alan Brown, President

CinemaQuest, Inc.

A Lion AV Consultants Affiliate


"Advancing the art and science of electronic imaging"
 

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Discussion Starter · #3 ·
If any of the figures I gave in my previous post are erroneous please post correct ones.


Being from Europe I am used to industry specifications being freely available to anyone who would like to know. I am interested from a enthusiast standpoint, I am not qualified or interested in voicing an opinion as to what the standards should be, as a member of the viewing public I am just interested in what they are. Could you tell me which documents I should read and if they are freely available online to the viewing public.
 

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It's fairly expensive, but thanks GeorgeAB....


I am going to sign up for the SMPTE Journal, I hope I can get past issues too or at least gain access to past articles.
 
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