In vaadin you can easily embed images either via:

Embedded logoEmbed = new Embedded("yourText",new ThemeResource("../yourtheme/img/logo.png"));
logoEmbed.setType(Embedded.TYPE_IMAGE);

or if you need a linked image do the following:

Link iconLink = new Link();
iconLink.setIcon(new ExternalResource(urlAsString));
iconLink.setResource(new ThemeResource("../yourtheme/img/logo.png"));

But how can you scale that external image? This is simple if you let the browser do it for you. In Java do:

iconLink.setStyleName("mylogo");

and then you will need to change the following style in your custom style.css to your needs:

.mylogo a img { width: 67px; }