WordPress at a glance
filter is not described

wp_get_attachment_thumb_file filter-hook . WP 2.1.0

Filters the attachment thumbnail file path.

Usage

add_filter( 'wp_get_attachment_thumb_file', 'filter_function_name_949', 10, 2 );
function filter_function_name_949( $thumbfile, $post_id ){
	// filter...

	return $thumbfile;
}
$thumbfile(string)
File path to the attachment thumbnail.
$post_id(int)
Attachment ID.

Where the hook is called

wp_get_attachment_thumb_file()
wp-includes/post.php 5430
return apply_filters( 'wp_get_attachment_thumb_file', $thumbfile, $post->ID );

Where the hook is used (in WP core)

Does not used.