2022.12.09 01:29 "[Tiff] How to write multi-file TIFFs", by L. E.
Segovia
Thread
2022.12.10 09:35 "Re: [Tiff] How to write multi-file TIFFs", by Paavo
Right, sub_IFD-s are not widely supported by otherwise TIFF-capable software packages. That's the biggest argument against using them.
For reading sub-IFD-s you need to call TIFFGetField(tif, TIFFTAG_SUBIFD,...) and TIFFSetSubDirectory(...). After that, you are already in the correct place, no need to call TIFFReadDirectory(). TIFFReadDirectory() would be only needed for moving on to the next main IFD.
HTH
Paavo