Tuesday, December 09, 2008

The Dark Knight on Blu-ray Disc

December 2008 saw the release of THE DARK KNIGHT on Blu-ray Disc. This film was presented theatrically in two different film formats - 35mm film using conventional CinemaScope and IMAX using the higher rez 70mm film format. Whilst in the conventional cinema, the film was presented in CinemaScope 2.40:1, parts of the film had been originally shot for IMAX using the larger film format and was presented this way at specialty events capable of 70mm projection.

Bringing it home to Video has created some confusion as the Blu-ray Disc release of this film features the IMAX footage presented at full HDTV's 1.78:1 whilst the rest of the film is presented in a letterboxed format. It should be noted that real IMAX is actually closer to 1.44:1, so some material has been cropped to fit this in the 1.78:1 frame.

If you are like me and into CIH, then you can simply watch this film the way you most probably saw it in your local cinema - in CinemaScope - as the "Scaling" process used in CIH will remove the portions of IMAX footage outside the 2.40:1 frame along with the normal letterboxing black bars. However, if you wanted to create a system that will allow you to view this [and any future films in this format] you may need to combine both CIH and a really large 16:9 screen [with top and bottom masking] together.

Given that the BD version of the is film is trying to recreate the IMAX experience, you really want the IMAX portions of the film to be much larger than the rest of the film and given that Scope image height is based on seating distances, or vise versa, you want the Scope portions of this film to be maxed out for your seating distance so that when you see the IMAX parts, they are much taller. The letterboxing on the title means that approx 810 lines are used for the active picture and the remaining 270 are used to create the black bars. When the IMAX footage is seen, it will use the full 1080 lines. The idea of still using an Anamorphic Lens is to allow you to still watch all of your other "Scope" films the way they were meant to be seen, as well as keeping your other 16:9 program at the same height within the borders of the top and bottom masking.

The Screen:
What is required is a 16:9 screen the same width as the "Scope" screen you would normally use and this screen would have to feature removable top and bottom masking to allow you to create the Scope screen in the centre portion. This masking would remain in place for all programs except those shot in IMAX and maybe HD music videos like rock concerts. Your seating distances should still be worked out as if the Scope screen is the largest screen or minimum of 2x the height of the Scope screen not the 16:9 screen.

The Anamorphic Lens:
I use a Horizontal Expansion lens to allow me to create a Constant Image Height system should I chose to remove the lens from the light path of the projector. However I don't remove the lens and therefore if I had sufficient throw, I could use a Vertical Compression lens and achieve the same result. A VC lens would allow all 1080 lines to be vertically compressed into the same space as the letterboxed image allowing you to use the full panel of the projector. And this might just be the answer to this new problem. Whilst some HE anamorphic lenses are reversible [they also need to be turned 90 degrees or they will be a HC lens] to allow them to be used for VC operation, the throw must be sufficiently long.

Viewing the film.
This is probably the only case where you would be correct in watching this film in a letterboxed format. With the top and bottom masking removed, you would really experience the IMAX footage in proportion to the rest of the film based on your seating distance [SMPTE minimum is 2x the Scope image height]. for the Scope portions making the IMAX events eye candy at 1080 vs the 810 for the Scope portions. When watching other films, you would move the VC lens back in place to reduce the image height and close the top and bottom masking and use the system like a conventional CIH system. You might even want to add side masking for 1.78 and 1.33 program.

I don't think this will become a mainstream method of film making, so I am sticking with a 2.37:1 screen for now.


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