Hi Andy,
What format (not the same as file extension) are the images? I am not familiar with raster data being stored as .iso files. Esri uses .iso files to distribute our software these days. For example, ArcGIS 10.x software is provided in the form of downloadable .iso files after login with a valid user account on the Esri Customer Care Portal. An ISO file, often called an ISO Image, is in fact an "image" of an entire DVD.
After the ISO image file has been downloaded, it can be used directly from the system's hard drive as a virtual disk by using either an ISO image file extractor program to extract the files, or by using an ISO mounter program (e.g., Virtual CloneDrive). In addition, a copy can be created on physical media by using a DVD authoring program and DVD burner to burn the ISO image on DVD.
Do you know who made the aerials?
Best Regards,
Eric