With this option QlikView will attempt to interpret each expression value as a reference to an image. The reference may be a path to an image file on disk (e.g. C:\Mypic.jpg) or inside the qvw document itself (e.g. qmem://<Name>/<Peter>). If QlikView cannot interpret an expression value as a valid image reference, the value itself will be displayed, unless the Hide Text When Image Missing box is checked.
Looks like it has to be on your machine or in the the qlikview document. For dynamic images, you may try using if statements?