A method and apparatus for detecting a target or targets in a surrounding background locale based on target signatures obtained by a hyperspectral imaging sensor used the hyperspectral imaging sensor to collect raw target signature data and background locale data during a first data collection mission. The data is processed to generate a database including a plurality of target signatures and background data relating to the background locale. The hyperspectral imaging sensor is later used to collect further background data during a further, current data collecting mission so as to provide continuously updated background data, in real time. A covariance equalization algorithm is implemented with respect to the background data contained in the database and the updated background data collected during the current mission to effect transformation of each target signature of the database into a transformed target signature. A detection algorithm which employs the resultant transformed target signature is used to produce detection information related to the target or targets.