function triggerEvent(event, $el) {
        var handler = options['on' + event];
        if (handler) {
            if ($isFunction(handler)) {
                handler.call($el[0]);
            } else {
                if (handler.addClass) {
                    $el.addClass(handler.addClass);
                }
                if (handler.removeClass) {
                    $el.removeClass(handler.removeClass);
                }
            }
        }

        $el.trigger('lazy' + event, [$el]);

        // queue next check as images may be resized after loading of actual file
        queueCheckLazyElements();
    }