Vips is not reading all tags (metadata)

[boan-jfm]

Hi

I used exiftool to write the 'Creator' tag (exiftool -Creator="Bo Andersen" php-vips-meta-tags.jpg) to an image, but when I try to read it using php-vips getFields or vipsheader -a, it's not included in the output.

exiftool output - has the creator tag

vips output - missing the creator tag

Test image

How do I get the information in php-vips?

Thanks.

[jcupitt]

Hi @boan-jfm,

Creator is part of XMP (I think), so libvips doesn't handle it for you directly. You'll need to get the xmp-data field and decode that using an xmp library.

You can see all the exif tags here:

https://exiftool.org/TagNames/EXIF.html

JPEGs also have ICC profiles (containing many internal metadata fields) and IPTC data blocks (with even more metadata).

[boan-jfm]

Thank you.

Creator is part of XMP (I think), so libvips doesn't handle it for you directly.

Just out of curiosity, what types of metadata formats does libvips handle directly, is it "only" exif-tags?

[jcupitt]

It'll read and write all JPEG metadata, but it only decodes EXIF into separate tags.

You can't really read JPEG correctly without looking inside the exif, unfortunately, since you need that to handle things like camera orientation. But the other metadata can just be treated as byte arrays (from libvips point of view).

I suppose it reads inside ICC profiles too, but none of that internal detail is exposed in libvips metadata.