The normal aspect ratio for digital image capture is 1.89.
DCI-compliant films will either be “flat” at 1.85, or “scope” at 2.39.
If an IMAX film-out is required for 3D, or a digital 4×3 version
is required for 3D (see point 38 for dome conversion), the 1.89 master image
will need to be cropped to 4×3 (For content taller than 1.9:1 up to 1.43:1 full screen material,
pre-process the image in your DCP package by squeezing the vertical dimension
by exactly 24.8%. The anamorphic lens of the projector will expand the image to
the correct ratio), or shot extensions will be needed to build the 1.89
up to 4×3 (see section 25).
