This Image Browser plugin allows images on the server to be browsed and picked for inclusion into the editor's contents.
This plugin integrates with the image plugin (part of CKEditor), by making it provide a Browse Server button in the Image dialog window (screenshot here).
The way you use it is very similar to imageGetJson in Redactor. In fact, it uses the same data format, allowing for an easy transition between the two.
See the Usage section to learn more.