As of 4Dv14 R3 unsupported images that cannot be rendered due to the machine have an icon displayed. In older versions of 4D the image would just present a blank transparent rectangle where the image should have been as shown below:


Now the following image below is displayed in its place with the format extension labeled underneath.


Some formats that are not rendered correctly are PDF pictures on a Windows platform and PICT-based pictures on 64-bit 4D Server on OS X.