Current IPTC digest: is the XMP still in sync?

A JPEG can hold the same caption, keywords or copyright twice: in the old IPTC IIM block and in XMP. Photoshop added a way to detect when only one of them was edited. When it saves, it writes an MD5 hash of the IPTC data into Photoshop resource 0x0425 in the APP13 segment. Later, a reader hashes the IPTC block again and compares.

ExifTool shows both sides. The stored hash is Photoshop:IPTCDigest. The hash it computes from the IPTC that is in the file right now is File:CurrentIPTCDigest. Matching values mean nobody changed IPTC behind the XMP's back.

A mismatch, reproduced

Start from a file where the two agree, then write one IPTC field directly:

exiftool -IPTC:Credit="Doe Studio" iptc.jpg
exiftool -a -G1 -s -Warning -IPTCDigest -CurrentIPTCDigest iptc.jpg

[ExifTool]      Warning                         : IPTCDigest is not current. XMP may be out of sync
[Photoshop]     IPTCDigest                      : 3f6e6be1ac45b3b874b87b90caab2ede
[File]          CurrentIPTCDigest               : fe6b7cc6b5aac48ca6ca3ff60a247c68

The Metadata Working Group guidance, which ExifTool's MWG module follows, says what to do with that: if the stored digest exists and doesn't match, the IPTC is newer, so prefer it over XMP. If the digest matches, or there is none, prefer XMP. Software that ignores the digest may show the old XMP credit and never the new IPTC one.

Getting back in sync

Copy the IPTC values into XMP and store a fresh digest in one pass. The args file ships with ExifTool in its arg_files folder:

exiftool -tagsfromfile @ -@ iptc2xmp.args -IPTCDigest=new iptc.jpg

On the test file, that filled XMP Credit, Creator and Rights from IPTC, and both digests read fe6b7cc6b5aac48ca6ca3ff60a247c68. Running -IPTCDigest=new alone, or deleting the digest with -Photoshop:IPTCDigest=, also clears the warning, but leaves the XMP stale. Do that only once the two blocks agree.

To avoid the problem, write shared fields through ExifTool's MWG tags, such as -MWG:Copyright=. They set EXIF, IPTC and XMP together and refresh the digest, but only if it was current before the write: on the already mismatched file, the digest stayed stale. The digest is not exposed in our editor. The EXIF vs IPTC vs XMP guide explains why the same field lives in several places, and the JPEG format page shows where APP13 sits.