Manual:$wgMediaHandlers

Images: $wgMediaHandlers
Plugins for media file type handling.
Introduced in version:	1.10.0 (r21411)
Removed in version:	still in use
Allowed values:	(see below)
Default value:	None

Other settings: Alphabetical | By Function

Details

Plugins for media file type handling. Each entry in the array maps a MIME type to a class name.

Default value :

$wgMediaHandlers = array(
    'image/jpeg' => 'BitmapHandler',
    'image/png' => 'BitmapHandler',
    'image/gif' => 'BitmapHandler',
    'image/x-ms-bmp' => 'BmpHandler',
    'image/svg+xml' => 'SvgHandler', // official
    'image/svg' => 'SvgHandler', // compat
    'image/vnd.djvu' => 'DjVuHandler', // official
    'image/x.djvu' => 'DjVuHandler', // compat
    'image/x-djvu' => 'DjVuHandler', // compat
);

Note: All the used classes are listed in that variable and they are in includes/media