Imnsi,
…because MAC’s don’t seem to like file extensions.
It’s not that Macs don’t like file extensions; they don’t need them. The Mac’s newest operating systems (OS X) are, at least, more aware of file extensions (because of its Unix roots) and easier by design to network with Win machines, making it less likely you’ll see files without extensions down the road.
There are, however, many Mac users still on the older "classic" OS, and your best bet is to ask such users to — pretty please — save with filename extensions. It’s usually a simple matter of checking a box in their application’s preferences.
There are standalone file viewers, such as Quick View Plus <
http://www.avantstar.com/intradoc-cgi/idc_cgi_isapi.dll?IdcS ervice=SS_GET_PAGE&ssDocName=QuickViewPlusOverview>, that do an excellent job of letting you view just about any file — image or otherwise — even those saved without a filename extension. I am not, however, aware of any utilities that will automatically determine file types and add the right extensions.
If you can get removable media containing the image files directly from those Mac users who refuse to save with extensions, you can use a Mac disk reading utility, such as Transmac <
http://www.asy.com/scrtm.htm>. Most such utilities will maintain a table of Mac file associations and Windows filename extensions, giving you the option to add extensions automatically when you copy the files to a local Win drive.
More info here <
http://developer.apple.com/documentation/MacOSX/Conceptual/B PFileSystem/Concepts/FilenameExtensions.html>.
=-= Harron =-=
