1. IMAX screens are big. Or at least should be according to movie lovers. That's why other regular sized IMAX are called LieMAX. Including the one in your screenshot (PVR at Lower Parel, right?). Even movies not shot in IMAX are a great experience on an IMAX screen.
2. Aspect ratio of IMAX film format is close to square. Which also has size and noise challenges due to actual film reel in it. That's not a problem with digital cameras like ARRI Alexa.
3. The screen in your photo doesn't have aspect ratio of proper IMAX as far as I'm aware. It's just a normal multiplex sized screen with IMAX branding. Otherwise there would be more screen on top and at bottom to accommodate proper IMAX format as and when required.
The Batman has aspect ratio of 2.40:1throughout, which is a standard ratio for movies. Dunkirk had scenes in 1.43:1 ratio which filled the IMAX screen at Wadala.
See for yourself the difference between the two (top left vs bottom right)
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