OpenEXR (designed for, and used by the VFX industry) supports dimensions up to int32 = 2 billion, but is a float16/float32 pixel format only (It can do int32 fo

OpenEXR (designed for, and used by the VFX industry) supports dimensions up to int32 = 2 billion, but is a float16/float32 pixel format only (It can do int32 for IDs, so technically you could multiplex/combine/bitshift 8-bit values into one int32 if you really wanted).