Tableau's online documentation
Static image files can be added to the dashboard. You could wish to include a logo or a detailed diagram, for example. You are invited to choose an image from your computer when you create an image object. You can also specify the URL of a picture posted on the internet. When you add an image to a dashboard, you can choose from a menu of options to personalise how the picture appears. You may choose to Fit Image, which adjusts the image to the size of the image item on the dashboard, for example. You may also choose to Center Picture, which aligns the image with the dashboard's image object's centre. Finally, you select Set URL, which converts the picture into an active dashboard hyperlink.