Release status: stable
|Description||Attempts at extracting metadata from commons pages|
|Author(s)||Brian Wolff (bawolfftalk)|
|Compatibility policy||release branches|
|License||GNU General Public License 2.0 or later|
|Translate the CommonsMetadata extension if it is available at translatewiki.net|
|Check usage and version matrix.|
|Issues||Open tasks · Report a bug|
The CommonsMetadata extension is an attempt at extracting metadata from Wikimedia Commons pages but is also available at all other Wikimedia projects. It adds some extra information to the imageinfo API, based on templates and categories in the image description. It is used by a number of extensions / tools (such as MediaViewer, VisualEditor, MobileFrontend, Mobile-Content-Service (MCS)) to provide better lightboxes or image selection dialogs.
The extension in its current form is intended to be a temporary solution, eventually replaced by Wikidata on Commons.
Motivation & design choices
The assumptions of this extension are the following.
- At some point in the future, wikidata will take over handling metadata at commons. In order to avoid disruptive changes, which will soon need to be changed again, the extension should work with commons metadata as it currently is (so not introducing new parser functions). Hence screen scraping.
- The content of many of the fields on a commons description page include rich formatting (In particular: Links, italics, bold. In some cases more complex things like embedded images)
- As a result, extension outputs parsed html (wikitext sucks, plain text doesn't capture the data)
- Futhermore, the data tends to be formatted for human display, rather than (for example) machine formatted dates. When the date field says something like "circa 1600s", its hard to convert that to a precise date (otoh, many examples can be).
- To carry that forward, also apply formatting to exif metadata, which is controlled on wiki (For example, commons links the camera name to a wikipedia article)
- If we can't extract info from the description page, but the file has the author tagged in exif/XMP/iptc metadata, we should use that as a fallback.
- Ideally such a system would be as commons-inspecific as possible, with the commons and non-commons part separated.
- Commons description pages have multilingual descriptions. Lots of users probably just want one language.
- In this implementation, it applies per language conventions to dates and things. Additionally for explicitly multi-lingual fields (description), there is an option to return all, or just a single language. Even in single language mode, some things are still language specific (like the thousands seperator on numbers)
- Download and place the file(s) in a directory called
- Add the following code at the bottom of your LocalSettings.php:
wfLoadExtension( 'CommonsMetadata' );
- Done – Navigate to Special:Version on your wiki to verify that the extension is successfully installed.
To users running MediaWiki 1.24 or earlier:
The instructions above describe the new way of installing this extension using
wfLoadExtension(). If you need to install this extension on these earlier versions (MediaWiki 1.24 and earlier), instead of
wfLoadExtension( 'CommonsMetadata' );, you need to use:
|Warning:||If you're developing or testing this extension, we do NOT suggest you copy the Commons templates for image metadata, as they take extremely long to compile and have complicated dependencies like Scribunto. Instead, get an expanded version that has only wikitext/HTML and put in the various parameter references (or don't) manually. You can find an example (to be used with Special:Import) here. Or use Vagrant which includes certain templates by default.|
When testing with remote images (e.g. Commons images if you have enabled
$wgUseInstantCommons), you can set
$wgCommonsMetadataForceRecalculate = true; to force CommonsMetadata to parse the description page of the image and extract the metadata (normally, if the remote repository had CommonsMetadata installed as well, it would just copy the API output from there).
Use the imageinfo API, and include
extmetadata as an image info property specified via
View this example in the API sandbox:
The extension currently provides the following items in the
extmetadata field of the response (the field names were chosen, where possible, to follow the IPTC-IIM format used in EXIF headers):
Data based on machine-readable data in the Information template:
- ImageDescription - image description
- Artist - author name (might contain complex HTML, multiple authors etc)
- Credit - source
- DateTimeOriginal - time of creation (space-separated ISO 8601 timestamp whenever possible, but can be any other textual description of a date, possibly with HTML mixed in)
- ObjectName - title (for a book/painting; otherwise just the file name)
- Permission - contents of the Permission field of the template. Can be a lot of things (license template, OTRS id, details on how to attribute...)
- AuthorCount - the number of templates with authors (e.g. Book, Photograph...). The number of actual authors might be higher if a template describes multiple authors in a single string.
Data based on machine-readable data in the Location template:
- GPSLatitude - latitude
- GPSLongitude - longitude
- GPSMapDatum - coordinate type (only
WGS-84supported for now)
Data based on machine-readable data in the license template:
- LicenseShortName - short human-readable license name
- Copyrighted -
False(for public domain images)
For multi-licensed images these values are currently unreliable.
- Attribution - custom attribution that should replace Artist + Credit (can also originate from the Information template)
- AttributionRequired - booleanish (phab:T86726), tells whether there is a legal requirement to attribute
- NonFree - booleanish, true means the image is not under a free license. (Used for non-Commons images only.)
- CommonsMedadataExtension - contains the metadata parser version number; mostly for internal use
- License - a best guess at the license of the image (mostly for internal use by MediaViewer, might change; LicenseShortName is probably more reliable)
- Categories - a
|-separated list of the categories of the image.
- Assessments - a
|-separated list of the assessments of the image (currently five values are supported: poty, potd, featured, quality, valued). Based on parsing category names, probably won't work for images not hosted on Commons.
- Restrictions - reuse restrictions such as trademarks or personality rights; an array of keywords (the class names from this table, without the
restriction-prefix). See also the restrict-* icons in MediaViewer.
- DeletionReason - if set, the template is being considered for deletion. (Based on the nuke template, probably not reliable outside Commons.) It contains a deletion reason, but it is phrased to be applicable for a log entry, so it might be misleading (e.g. past tense when actually it is not yet decided whether the image will be deleted).
- How to add metadata
- Manual:File metadata handling
- Extension:MultimediaViewer - currently the main user of the information provided by CommonsMetadata.
- Request for comment on handling image information
- Template detection on local wikis with locally uploaded files – Describes how to prepare the templates for fetching metadata and thus displaying them when using the MultimediaViewer extension.
- Extension:CommonsMetadata/info template for 3rd-party wikis
|This extension is being used on one or more Wikimedia projects. This probably means that the extension is stable and works well enough to be used by such high-traffic websites. Look for this extension's name in Wikimedia's $2 and $3 configuration files to see where it's installed. A full list of the extensions installed on a particular wiki can be seen on the wiki's Special:Version page.|