ORF file are generated by Olympus cameras.
It if a TIFF file with a custom magic at the beginning: MMOR, IIRO or IIRS instead of the TIFF magic.
IFD 0 contain the main image. IFD 1 contain the 160x120 preview. Some file don't have the preview outside the.
Another peculiarity is thatand are arrays for the E10 files, unlike the others. Still consistent with the TIFF/EP standard.
Sometime the CFA does not look like it is compressed but seems to be organised weirdly. E400 has uncompressed CFA.