Things have changed since I last visited Lizardtech's website! To download Lizardtech products, go to https://lizardtech.com/download. They used to have a free "MrSID Viewer" and a free "MrSID GeoViewer," but now there is only something called GeoExpress View available. It looks like GeoExpress View is expensive, but there may still be a trial version. But if you want to use it for a long time, you may have to register it. The free viewers seem to be no longer available. There does also seem to be a free browser plugin.
In any case, the following info was correct as of October 2003, but things
appear to have changed again since then. If you download, install and run a
trial of GeoExpress View, you may be able to do the following to Export a MrSID
file as a full-resolution TIF file:
Once the Export process is complete, you can view the TIF with standard image-handling software such as Adobe Photoshop, or with GIS software if the original MrSID file contained a geographical coordinate system. NB: A MrSID file that is approximately 50 MB turns into a 660+ MB TIF file.
Email or call with any questions: Charles Kiblinger
tel: 5-7981.