org-html-inline-image-rules

org-html-inline-image-rules is a variable defined in `ox-html.el'.
Its value is

(("file" . "\\.\\(jpeg\\|jpg\\|png\\|gif\\|svg\\)\\'")
 ("http" . "\\.\\(jpeg\\|jpg\\|png\\|gif\\|svg\\)\\'")
 ("https" . "\\.\\(jpeg\\|jpg\\|png\\|gif\\|svg\\)\\'"))

Documentation:
Rules characterizing image files that can be inlined into HTML.
A rule consists in an association whose key is the type of link
to consider, and value is a regexp that will be matched against
link's path.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.4 of Emacs.