Got it! I Had just to add the IModel as argument in the ImageResourcePanel-Constructor.
`public class ImageResourcesPanel extends Panel {
/**
* The image names for which dynamic images will be generated
*/
private static final String[] IMAGE_NAMES = new String[] {"one", "two", "three"};
public ImageResourcesPanel(final String wicketId, IModel<Book> book) {
super(wicketId, book);
int refNumber = book.getModelObject().getRefNumber();
ListView<String> listView = new ListView<String>("list", Arrays.asList(IMAGE_NAMES)) {
@Override
protected void populateItem(ListItem<String> item) {
String imageName = item.getModelObject();
imageParameters.set("name", imageName);
imageParameters.set("ref_number", refNumber);
final ResourceReference imagesResourceReference = new ImageResourceReference();
final PageParameters imageParameters = new PageParameters();
// generates nice looking url (the mounted one) to the current image
CharSequence urlForWordAsImage = getRequestCycle().urlFor(imagesResourceReference, imageParameters);
ExternalLink link = new ExternalLink("link", urlForWordAsImage.toString());
link.setBody(Model.of(imageName));
item.add(link);
}
};
add(listView);
}
}`