Email Steve . Four individual NAPP photos are required to completely cover the area of a USGS 7.5 minute topographic map. These composite files are compressed using MrSID compression software. MrSid desiginates the image file as a .sid file with an associated .sdw file as a world geo-reference file. LizardTech has a free viewer that allows you to save all or part of a .sid file to geotiff format.
Some quads are partial color and black and white.
There will be both a .sid and c.sid file for these quads. The reference lists below can be used to determine the file name and degree area that you need. Most of the state is completed. A large area of eastern Mississippi will be finished by mid-summer 2001. Check back to see if your area of interest has been completed.