Get All Images in Media Gallery?

$query_images_args = array(
    'post_type'      => 'attachment',
    'post_mime_type' => 'image',
    'post_status'    => 'inherit',
    'posts_per_page' => - 1,
);

$query_images = new WP_Query( $query_images_args );

$images = array();
foreach ( $query_images->posts as $image ) {
    $images[] = wp_get_attachment_url( $image->ID );
}

All the images url are now in $images;