Regarding the problem with macOS ignoring "late" XMP info in PNG files - Topic 5347 (https://exiftool.org/forum/index.php?topic=5347.0)...
Suppose I have a PNG file and I'd like to know if it's going to be problematic on macOS. Is there an ExifTool command that can distinguish whether XMP blocks come before/after PNG IDAT? [More precisely: will ExifTool's output somehow expose XMP/IDAT ordering?]
Yes. From the PNGEarlyXMP API option documentation (https://exiftool.org/ExifTool.html#PNGEarlyXMP):
When reading, this option causes a warning to be issued if standard XMP is found after the IDAT chunk.
So this command should do what you want:
exiftool -api pngearlyxmp -a -warning FILE
Then look for a warning that says "XMP found after PNG IDAT".
- Phil
Thanks for your response Phil. However, your recommended command isn't giving me the advertised results.
I have a file that I think has XMP-after-IDAT - see the attached 'ScanThenMogrify03.png'. TweakPNG shows this having several tEXt chunks after IDAT. Mac OS X Preview's 'Inspector' window doesn't display GPS metadata in this file.
I'm using ExifTool version 10.25 running on OS X 10.10.5.
My exact command:
exiftool -api pngearlyxmp -a -warning ScanThenMogrify03.png
Should I see an error message for this command and file? Thanks for any feedback or insight.
This file is fine, and shouldn't give a warning. The XMP comes before the IDAT chunk. The stuff written after the IDAT chunk isn't XMP.
- Phil