A system for correcting detector array channel signal output level non-uniformities in a thermal imaging system. The non-uniformity correction system includes a target scene detector (27) having an array of detector elements (26a, 26b) responsive to energy from a detected target scene (14) and including a plurality of associated output channels (31, 32). The system includes a memory (62) for storing non-uniformity correction commands and a processor (82) operative to implement the non-uniformity commands in response to detected non-uniformities in the output channels signal. The system also includes a non-uniformity corrector (60) for adjusting the level of the output channels in response to commands from the processor (82).