This plugin seems to be abandoned. I have upgraded from ES 1.3.9 to 2.2 and this plugin is broken. I see two old pull requests on git that have been ignored. Please mark it as abandoned in the Elasticsearch documentation.
FYI the plugin is continued at https://github.com/kiwionly/elasticsearch-image
Thank you!
Alas, that seems to be broken, too. I get
MapperParsingException[Mapping definition for [img] has unsupported parameters: [feature : {CEDD={hash=[BIT_SAMPLING]}, JCD={hash=[BIT_SAMPLING, LSH]}}] [metadata : {jpeg.image_height={type=string}, jpeg.image_width={type=string}}]]