You can convert LizardTech MrSID images (.sid) to common TIFF format (.tif, .tiff) using Total GIS Converter or similar utilities. This is most likely used for conversion of maps to common pictures. All special data will be lost and you will get just normal image.
Convert LizardTech MrSID image file format to Aldus Tagged Image File Format (TIFF) bitmap image.
We have found 2 software records in our database eligible for .sid to .tiff file format conversion.
Microsoft Windows software - convert sid to tiff on Windows
A dedicated converter for SID format
Convert from sid file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned sid to tiff. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A converter that is able to transform various GIS file formats