Image correction methods and systems are disclosed that correct raw values, including, subsequent to closing the shutter, acquiring a current raw value table, determining an offset correction table for the current temperature of the detector as a function of the current table and a set of stored raw value tables, and correcting the stream of raw values using the offset correction table. A maintenance process includes testing a condition for replacing a table of the current set with the current table, and if the condition is met, replacing the table of the current set with the current table. This test includes determining whether there is a new set of tables obtained by replacing a table from the current set with the current table that is more relevant than the current set with regard to subsequently determining an offset table.