Pre-processing operations are performed on remotely sensed data prior to information extraction. Remove error encountered in remotely sensed data (most common are radiometric and geometric error) to get as close as possible to the true radiant energy and spatial characteristics of the study area at the time of data collection. Image preprocessing includes any steps that facilitate information extraction (image display and enhancement).
Pre-processing of EO data focuses on processing the electrical signal measured by a sensor to a processing level at which pixel values subsequently can be used for information extraction. This includes correction of sensor system errors, geometric and radiometric correction. EO data are an information source for multiple purposes with different needs for pre-processing. Some applications may need only basic pre-processing to be done, others need a higher level. Depending on the sensor type (optical, radar, lidar), different processing levels are established.