My knowledge level about photo metadata is hovering just below what I need to know to do the things I want to do. I searched online and found a few good articles but thought folks here could recommend something specific. Today I started out just trying to learn what 'IFD0' refers to as I see there's an ImageDescription tag in that group, but it made me realize there's so much I don't know. In the MacOS Preview app, when I click the Info button to look at a photo's metadata, I see five tabs: General, EXIF, IPTC, JFIF, TIFF. I know EXIT and IPTC but not the other three. Thanks for any recommendations for a newcomer starting out with this.
Quote from: sftoprov on April 14, 2023, 11:42:59 AMI searched online and found a few good articles but thought folks here could recommend something specific.
Unfortunately, I don't have any links beyond the specs such as the IPTC Photo Metadata Standard (https://www.iptc.org/std/photometadata/specification/IPTC-PhotoMetadata) and Guidelines for Handling Image Metadata (https://web.archive.org/web/20180919181934/http://www.metadataworkinggroup.org/pdf/mwg_guidance.pdf). Metadata is a mess and many of the pages I've looked over try to simplify it but do it badly.
I honestly fee that unless you have a real interested or need in the details of metadata, using Digital Asset Management (DAM) program are the best option, as they make it easier to deal with in standard ways that will transfer correctly from program to program and are more adaptable to future standards/programs.
QuoteToday I started out just trying to learn what 'IFD0' refers to as I see there's an ImageDescription tag in that group
It's my opinion that you should always write the tags in their simplest form. The tag name by itself if possible, such as just
ImageDescription, the group name if needed, as with
IPTC:City and
XMP:City, and only use specific groups if absolutely necessary, as with
XMP-xmp:Rating and
XMP-acdsee:Rating.
I especially advise this with EXIF tags, as it isn't obviously which subgroup a tag might belong to. This can lead to errors if you write a tag to the wrong subgroup by mistake and can take time to figure out what went wrong. For example, there are some cameras that write the
ModifyDate tag to the wrong IFD# and this causes problems when trying to edit that tag.
QuoteIn the MacOS Preview app, when I click the Info button to look at a photo's metadata, I see five tabs: General, EXIF, IPTC, JFIF, TIFF. I know EXIT and IPTC but not the other three.
I would assume "General" would be file system related tags, but I don't use a Mac, so I can't really comment on it.
I really wonder why JFIF would be there, since there isn't anything there beyond resolution tags and maybe a thumbnail image. And thumbnails in EXIF are more likely to be used. See the JFIF tags page (https://exiftool.org/TagNames/JFIF.html).
I believe the TIFF tab contains data that exiftool puts in the EXIF group. If I recall, someone did some work on these forums looking into the TIFF tab.
Figuring out this stuff is a tedious game of filling all possible tags, checking the results, removing an item, checking again, etc.