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Author Topic: 3D peak white test pattern Antti Nayha Master Film Handler Posts: 268 From: Helsinki, Finland Registered: Oct 2008 posted 08-29-2012 04:50 AM                     According to "The EDCF Guide to 3D Cinema" (March 2011), page 25, you should always use a dedicated "3D peak white test pattern" when measuring 3D light levels through the glasses. I've seen a lot of people getting weird results when trying to measure 3D brightness with active shutter glasses and the projector's full-white 2D test pattern. Apparently that way you are ignoring the 3D dark time, resulting in a measurement which is much too high. Is such a 3D peak white test pattern available somewhere? Or is it as easy as creating one from two full-white still images with OpenDCP?  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 08-29-2012 07:10 AM                     How should a 'different' white pattern solve the issue of measuring through shutter glasses? - Carsten  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 08-29-2012 11:50 AM                     Because when playing back a projector's internal test pattern, 3D settings are not activated, so the glasses probably would not sync and the pattern will not triple flash. Additionally, the desired MCGD is not activated. Playing content off the server, with the server set for 3D playback and the correct title on the projector activated, would solve this.  |  IP: Logged Antti Nayha Master Film Handler Posts: 268 From: Helsinki, Finland Registered: Oct 2008 posted 08-29-2012 12:02 PM                     Exactly. Just for the sake of science and fun, I made two peak white DCP's - one in 2D and another in 3D - and played around with them a bit. The brightness readings were as follows: - 33.4 fL (2D peak white) - 26.5 fL (3D peak white, without glasses) - 2.8 fL (3D peak white, through XpanD X101 glasses) The last two measurements were made with the projector in 3D mode, with 6:2 triple flash and XpanD's current recommended 3D settings (a dark time of 1100 µs). I have to say was a bit shocked about the through-the-glasses reading. XpanD's marketing claims 17–18%, but I only got around 11%. Admittedly, the pair of glasses that I used for testing was two years old and not 100% clean... but I guess that just gets my test closer to an average real-world scenario. If anyone's interested, I'll be happy to upload both test DCP's.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 08-29-2012 12:35 PM                     quote: Antti Nayha 2.8 fL (3D peak white, through XpanD X101 glasses) Worse than Drive-in fL's .. and with no 3D. Being that low, is the picture on the screen viewable being so dim?  |  IP: Logged Antti Nayha Master Film Handler Posts: 268 From: Helsinki, Finland Registered: Oct 2008 posted 08-29-2012 12:54 PM                     I didn't test with actual content yet, but these were not the "house settings" for 3D anyway. Just playing around with the lamp set to minimum wattage. Still, my result just can't be right. If they were, the 3D light output would actually be only around 8% compared to the 2D test pattern with the same lamp settings. I'm going to do some more testing tomorrow to see if there was something wrong with my test clip and/or procedure. Surely the Harkness Digital Screen Checker can handle triple-flash 3D?  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 08-29-2012 03:34 PM                     Ah, alright, didn't get it you were comparing an in-projector test pattern to a DCP test pattern. Of course it doesn't make sense to measure through the glasses without the triple-flashing and glasses-sync going on. Now the question is what kind of instrument did you use? And why 'minimum wattage'? Of course it's irrelevant for relative efficiency, but you could easily get to decent levels by adjusting the lamp current? I guess that Xpand's numbers are 'best case', probably with select glasses and optimized flashing parameters. - Carsten  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 08-29-2012 03:41 PM                     Try disabling temporarily the colour correction. If you gain a lot of light it's probably wrong. Also, as said, those default values are usually improvable.  |  IP: Logged

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