Is there a list of file/image field subtokens?
For file https://www.drupal.org/node/390482#token-file
https://www.drupal.org/project/imagefield_tokens
and 
add https://www.drupal.org/project/filefield_paths   add this module 
for {The File (Field) Paths module extends the default functionality of Drupal's core File module, Image module and many other File upload modules, by adding the ability to use entity based tokens in destination paths and file names.}  

Check this screenshot: