When logged in as a portal administrator, and you have entered the Image module, click Edit Image Module Options. The following dialog box will be displayed:
In order to provide the visualization of an image not located on the site in the Image module, select URL at Link Type. Enter the url of the page where the image is located, if it is the first time this address has been used in the portal. Instead if it is a previously used URL, click Select an existing URL. At Alternate Text, enter the text to be displayed when the image is moused over by a visitor. At Width and Height enter the image dimensions: if such data is not specified the image will be displayed as its original size.
In order to proceed with the insertion click Update.