GDAL - Geospatial Data Abstraction Library

GDAL is a translator library for raster geospatial data formats that is
released under an Open Source license. As a library, it presents a single
abstract data model to the calling application for all supported formats.

GDAL is in active use in a few projects, and includes a number of
formats. Current translators include GeoTIFF (read/write), Erdas Imagine
(read), ESRI .BIL (read/write), .aux labelled raw (read/write), DTED
(read), SDTS DEM (read), CEOS (read), JPEG (read/write), PNG (read/write),
Geosoft GXF (read) and Arc/Info Binary Grid (read). A full list is
available in Supported Formats.

WWW: http://www.remotesensing.org/gdal/