Each installation of ArcView, ArcEditor, and ArcInfo has the ability to encode single raster files to MrSID format by default. Any single raster, less than 50MB in size, can be encoded with every installation of ArcCatalog. With the purchase of the additional MrSID license, multiple rasters of total size less than 500 MB can be encoded into one MrSID format raster file.
The above sizes are raw, uncompressed file sizes. If the input raster is 49MB or less, but is compressed, it may not be able to be encoded with the unlicensed core encoder. If the original image is already very highly compressed, the extra licensed encoder may not be able to encode the image either (depending if the raster is larger than 500 MB when it is uncompressed). The following example illustrates the formula ArcGIS uses to determine input raster file size. Also, see the online help on the Raster to MrSID encoder provided inside ArcToolbox.
A raster dataset's size is calculated by multiplying the raster's width (in pixels), the raster's height (in pixels), and the number of bands contained in the raster. For example, an 8 bit RGB TIFF raster that is 1000 pixels by 1000 pixels is 2.86 megabytes ((1000 x 1000 x 3) / 1048576) = 2.86 MB. Depending on whether the 500 MB license has been purchased, or simply the default 50 MB capability is available, determines how large of a raster can be encoded to MrSID format.