Déjà vu

CIPA has recently released a "Multi-Picture Format" (MPF) standard for storing large images in JPEG files. Again, there is a big problem with this standard: It uses offsets that are relative to the start of the MPF header (in the new MPF APP2 segment) to reference images after the JPEG EOI. These offsets will quickly be broken if any data after the MPF segment changes length. This problem could have been avoided if offsets had been specified relative to the end of file, but it is too late for this now that the specification is public.

The only workable alternative I can see is to enforce the rule that the MPF APP2 segment must come after all other APP segments. (It would have been smart if this was specified in the CIPA standard, but sadly this isn't the case.) If this is done, then metadata in the remaining APP segments (EXIF, IPTC, XMP, etc) can safely be edited without breaking the MPF offsets. I suggest that all metadata editors employ this strategy, regardless of the segment order specified in the standard (which says that the MPF APP2 segment must come immediately after the EXIF APP1 segment).