Image meta data is incredibly complex, because there is IPTC and EXIF, each with hundreds of options, and each manufacturer and application often setting them differently.
X3 currently uses 2 fields
title and
description from the image IPTC data. "Title" and "description" may be referred differently from other applications for example name, caption, documentTitle and more. X3 gets them by special codes reference (just so you know the actual codes):
data['title'] = $iptc["2#005"][0];
data['description'] = $iptc["2#120"][0];
There is another option for setting titles and description, but we have not yet tested it properly or figured a way to implement it for editing. In each page, you can create a list of data for each image like this:
filename.jpg:
title: Image Title
description: This is the description right here.
another.jpg:
title: Nice Smile
description: Watch the kids smile as the clown arrives.
Also, you are aware that you can rename any file to create its title? For example
"our_trip_to_kansas.jpg" will display in the page as
"Our Trip To Kansas".
We will extend this at some point, but for now the above information is all I can offer ...