Rename Featured Image

This plugin updates the image title (post title) and file name which is set as featured image when publishing the post.

Bulk Rename

This plugin has settings page through which you can rename the title and file name of all the post featured images to their respective post title. It has filter to check if already same file name (from the attachment url) as of post title.
The post title is sanitized before applying as new name to attached image.

It has an “Force Rename button” for renaming all images forcefully. It helps to update partially renamed images and disable the filter mentioned above.