如何使用cobra/lobo html呈现器访问dom节点的css属性

我正在尝试如何使用cobra/lobo工具包访问dom节点(在本例中为<img>节点)的css属性。我现在的情况是:

    UserAgentContext uacontext = new SimpleUserAgentContext();
    DocumentBuilderImpl builder = new DocumentBuilderImpl(uacontext);

    URL url = new URL(TEST_URI);
    InputStream in = url.openConnection().getInputStream();

    Reader reader = new InputStreamReader(in, "ISO-8859-1");
    InputSourceImpl inputSource = new InputSourceImpl(reader, TEST_URI);
    HTMLDocumentImpl d = (HTMLDocumentImpl) builder.parse(inputSource);
    HTMLCollection images = d.getImages();

    for (int i = 0; i < images.getLength(); i++) {

        HTMLElementImpl n = (HTMLElementImpl) images.item(i);
        AbstractCSS2Properties curr = n.getCurrentStyle();

        System.out.println("Image " + i + ": " + curr.getPropertyValue("background-color"));
    }

现在,这似乎只给我直接设置样式-而不是继承或计算样式。我怎样才能得到这些呢?

谢谢