The default output format for an Image or ArcMap Service is defined at the time the service is created; however, clients can use ArcXML syntax to send a GET_IMAGE request, specifying that the image be returned in another valid output format. In some circumstances, it may be necessary to disable this capability. Instructions provided describe how to restrict the format of the output returned for a GET_IMAGE request in Image and ArcMap Server.
The output type can be restricted so that only the default format can be returned. This involves setting the value of the SpatialServer.AllowOutputTypeChange property in the Esrimap_prop file to false. When set to false, Image and ArcMap Server ignore the OUTPUT type attribute in GET_IMAGE requests, and the image is returned to the client in the format specified at the creation of the service.
This information and procedure can also be found in ArcIMS Web help at ArcIMS Help > Securing your services and Web site > Setting Spatial Server restrictions when using the Servlet Connection. A link to ArcIMS Web help is in the Related Information section of this article.