It would be very useful to have a clean way to import images into another wiki,
especially into a central repository like Commons. Maybe the same mechanism
could be used by non-wikiemdia wikis to import images from Commons or Wikipedia.
The import should include the image description (all revisions), and
(optionally?) all versions of the file. For a clean import of the description-
and upload history, a shared userbase (aka single login) would probably be required.

Some suggestions for the implementation:

• There should be an image-import permission, so this feature can be restricted

to sysops if desired.

• The list of possible source wikis should be fixed. Some per-source

configuration is probably required.

• The import interface should be a special page.
• The import should have two stages: in the first, the source wiki and file to

import is specified. In the second, the import can be further refined.

• The image to transfer should be shown in the second step, to avoid mistakes.
• A checklist of image versions could be presented, so the user can choose which

versions can be ignored.

• The imported description text should be shown for further editing. The user

importing the file would become the author of a new revision of the description
text.

• The imported description text could be mangeled automatically, to insert

interwiki-prefixes into links, convert well known templates (esp. license tags),
etc.

• The description text (all revisions) could be imported using the

Special:Export interface, if direct access to the wiki's database is not
possible. This could be configured on a per-source-wiki basis.

• The Special:Export interface would need to get an option to export the upload

history of a file.

• The files themselves could be copyied on-disk, if the upload directories of

source and target wiki are on the same server (which is the case for most
wikimedia wikis, but not all). If that is not the case, the images can be loaded
via HTTP, perhaps using Special:Filepath

• Since the import potentially involves quite a bit of slow and unreliable

interaction over the net, care must be taken to implement transactinal logic in
order to prevent partial/broken imports.

A clean & easy way to transfer images between wikis has often been requested. I
am putting this here to have a place for tracking and discussing the issue, and
collection thoughts on the technical side of things.

Version: unspecified
Severity: enhancement