Shaun666 i went to the IMAX in Crawley to see it and it was good. I'm wondering what screen you were in as a couple of weeks ago i went to see x-men and that seemed to suffer from what you are mentioning, it was so dark in places that with the added darkness of the 3D glasses i struggled to see what was happening, i think it was screen 14 or 15, downstairs to the left.
Sorry, the screen we're talking about (screen 14) isn't the IMAX screen, screen 14 is probably the smallest screen they have at Crawley. The IMAX screen is the newest there and is always alot clearer than the older screens although i have been a couple of times 1st showing of the day where they have had to stop the film after 10 minutes to recalibrate and start from the beginning again.Our local Odeon cinema uses two 2k projectors working simultaneously for IMAX 3d presentations. I suppose this adds up to the advertised 4k presentation and might account for the apparent dimness of the picture. IMAX do use other systems but one is forced to believe that this is a cheap solution. They are experimenting with a system using lasers. IMAX 3D is not to be confused with Real 3d used on normal screens.
Incidentally running two projectors at the same time is not new. The first 3d presentations in the fifties used both projectors. This presented a number of problems. Normally they were only expected to show 20 minute reels alternately so they spliced 2 20 minute reels together. There had to be an interval after 40 minutes to change reels. Of course both projectors had to run in sync and if a portion of film was damaged on one reel it had to be matched at the same point on the other by splicing in blank frames. Another problem was overheating because the lamps were used to having a 20 minute rest period. Customers often complained about headaches and 3d films were dropped after only a few being made. Later 3d used the blue/green specs which were also unsatisfactory.
So if I understand correctly, the Tiff (Loseless) frames of the movie are being compressed to a lossy (jpeg2000) format. Since each Tiff frame is only 10MB/s, so 240MB/s which means a 2.5 hour film is 2160GB uncompressed, now lets say adding the extras eg audio, would make it 3TB. 3TB dcp file on hard drive seems manageable, as the drive can be reused for another film. Why use JPEG2000 compression then, unless there is no visible difference between the uncompressed Tiff and jpeg 2000 dcp file when viewed on a large projection screen.
From the image below the difference is clearly apparent.
JPEG 2000 - Wikipedia, the free encyclopedia
Digital Cinema Deluxe care to shed some light on this?
You know shortly after leaving school many moons back I really wanted to be a projectionist......fortunately I chose a different career path as they must all be gone by now?
I was a 35mm film projectionist for 6 years, however, we have all been replaced by computers. I would complain if it wasn't for the clarity of modern digital cinema.