photo-metadata

Photo metadata

Overview

Metadata embedded in an image file travels with the file. Photo CMSs (Photo Mechanic, Lightroom, Capture One) and wire intake systems read a photo's caption, credit, and rights from its IPTC and XMP blocks, not from a separate document or the email it arrived in. If the caption, credit, alt text, and license are not inside the file, they are gone the moment the photo is downloaded, forwarded, or re-uploaded.

One exiftool pass writes the EXIF, IPTC, and XMP layers together and leaves every other tag (camera settings, shot time) untouched. Modern software reads XMP first, legacy IPTC-IIM second, EXIF only for date and GPS, so write XMP everywhere and add IIM as a compatibility copy on JPEG/TIFF (HEIC, AVIF, and WebP have no IIM slot at all; see reference.md).

Two things changed since this workflow was "caption, credit, copyright." First, how an image was made now belongs in the metadata: the IPTC Digital Source Type field labels a camera photo versus an AI-generated one, and platforms (Meta, Google) and the EU AI Act increasingly read it. Second, cryptographic provenance (C2PA / "Content Credentials") is arriving on wire images and cameras, a signed layer exiftool can read but not write. Both are covered below.

A capable model already knows the field names. The hard part is not the mechanics, it is the judgment below. Lead with that.

When to use

• Prepping press photos for a wire so partner newsrooms can search, credit, and republish them
• Adding required photographer attribution and a reuse license before publishing or sharing
• Labeling how an image was made, a straight photo, an AI-generated illustration, an AI-edited composite
• Batch-tagging a shoot (a folder of images)
• Making images accessible (embedded alt text) and rights-clear (copyright or Creative Commons)
• Reading and sanity-checking the C2PA Content Credentials on an image that arrived from an agency

When not to use: editing pixels (this is metadata only); writing alt text for an HTML <img> (use accessibility-compliance); preserving web pages as evidence (use web-archiving); signing a Content Credential (exiftool can't, use c2patool, below).