Is it possible to save metadata in an image?

Question

We create thumb images on our server and I'm looking for a way to save metadata (text) in that image. Is that possible?

At this moment we use PHP and we create JPG images.

Answer 1

EXIF or reuse an old "data-hiding" concept, Stenography

Answer 2

Depends on the format. JPEG has EXIF, XMP, and IPTC. Here's a nice page on the topic.

Answer 3

Embedding XMP Metadata in Application Files (PDF)

Answer 4

Yes, it's possible.

You can use the almighty Exiftool perl utility, which handles nearly every known set of tags, both standard(EXIF, IPTC, Adobe's XMP, etc) and proprietary ones.