While we await support for the 4th generation MrSID® file format in AutoCAD, how can you know if your MrSID® image is a 4th generation or not? Because all generations have the .sid extension, the file extension won't tell you. Here's one way you can find out:
1. Launch the program GeoViewer (a free download from www.lizardtech.com).
2. Go to File > Add Layer > Local Layer to bring in the image.
3. Once the image appears, go to Layer > View Layer Metadata.
4. Look under "Image properties". In the value for Format, a generation 4 MrSID will show MRSID/MG4RASTER.
Other generations will show other formats (e.g. MG2 if it's a MrSID generation 2).