By default the when editing an item in the Media Item Editor of an item in Independent Media Items (IMI) you get 5 fields
Title, Description, Copyright, Keywords and an automatic field called fileName
These fields are defined on the server where LUNA is running.
To change these fields edit the following file on your server and restart LUNA's tomcat.
~/LunaImaging/7.x/LUNA/repository/DEFAULT~0~0/Media/MediaFields.csv
Each line in this text file represents a predefined field
Adding predefined custom fields for Media Items of collections
You can add predefined custom fields to any collection by creating a text file on your server called MediaFields.csv and placing it in your repository/<collection ID>/Media folder.