Besides the formats listed below, at version ArcIMS 9.1, ArcIMS also supports the JPEG 2000 image format on Windows and Solaris, and MrSid MG3 on Windows, Solaris and Linux.
Note: All listed and therefore supported image formats with a standard file extension can be added to ArcIMS Author through Catalog. Other formats will need to be added into the map configuration file (.axl) manually using a text editor and the ArcXML format as listed in the ArcXML Reference Guide.
Supported image formats (also listed in the ArcIMS Help system):