Geocoding, also known as georeferencing, is the geographical registration or coding of the pixels in an image. Geocoded data are images that have been rectified to a particular map projection and pixel size.
Raw, remotely-sensed image data are gathered by a sensor on a platform, such as an aircraft or satellite. In this raw form, the image data are not referenced to a map projection. Rectification is the process of projecting the data onto a plane and making them conform to a map projection system.
It is possible to geocode raw image data with the ERDAS IMAGINE rectification tools.