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Image Pr ocessing Systems     141

               classification incorporating contexture using the maximum likeli-
               hood classifier. PCI used to be similar to ERDAS in converting satel-
               lite imagery into land cover maps. However, PCI products have
               shifted the emphasis toward geometric processing of satellite images
               and stereoscopic aerial photographs. By comparison, image analysis
               functions are obscured in some add-on modules instead of featured
               prominently in the core products of PCI. The packaging of a few pro-
               grams into an add-on module makes this system highly fragmented.
               Although a high level of production efficiency is achieved through
               special customization for certain tasks, it is rather expensive for an
               educational institution to acquire all the add-on modules in order to
               teach core image analysis functions properly. Thus, this package
               serves the industry better than academic needs.
                   No matter which image analysis system is selected, the user must
               consider what modules are included in the standard package, what
               add-on modules to acquire, and whether user support should be sub-
               scribed to so that an updated version is acquired at a minimum cost
               when it is released. Another important consideration is the software
               licensing policy. When purchasing a license, the user must be aware
               of its restrictions (e.g., whether it is a commercial license or educa-
               tional license).  Another point to keep in mind is the number of
               licenses, or the number of users who have concurrent access to the
               system. Multiple licensing or site licensing is essential to an educa-
               tion provider or a large institution in which a team of image analysts
               are involved in a project. Normally, the system checks the number of
               concurrent users and allows the maximum number of users at the
               same time. However, if a license key is used, then the system can be
               run in a keyed machine only. Needless to say, this is highly inconve-
               nient and should be avoided.


          References
               Civco, D. L. 1996. “Review: ER Mapper 5.1 image processing software.”
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               Clark Labs. IDRISI Andes: GIS and Image Processing Software, http://www.clarklabs.
                  org/products/upload/Andes_Brochure.pdf, last accessed June 18, 2008.
               Cothren, J., and A. Barnes. 2006. QuickTake Review: ERDAS IMAGINE and Leica
                  Photogrammetry Suite 9.0, http://Geoplace.com.
               Definiens. 2008. Definiens Enterprise Image Intelligence Suite, http://www.
                  definiens-imaging.com/.
               ER Mapper. 2007. ER Mapper Professional Datasheet, http://www.ermapper.com/
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               ERDAS. 2003. ERDAS Imagine Field Guide. Atlanta, GA.
               Hermann, J. T. 2006. “IDRISI Andes Edition enhances modules, adds land change
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               ITT. 2007. ENVI—get the information you need from imagery, http://www.ittvis.
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               Page, M. 2006. Product Review: PCI’s Geomatica 10. http://www.directionsmag.com/
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