IFD0 vs IFD1 in EXIF

[blue-j]

Are IFD0 fields always about the primary image, and IDD1 about the thumbnail?

Families I've seen....

IFD0
IFD1
IFD2
SubIFD
EXIFIFD
InteropIFD

etc.  I think I've seen SubIFD1, maybe 2...

I can't say that the EXIF spec really helped me interpret these families and their meaning!  Any help would be sincerely appreciated.  : )

- J

[Phil Harvey]

For JPEG images, IFD1 is the thumbnail.

For other types (TIFF, DNG, RAW), IFD1 may store other things.

- Phil