SHUTTERLESS CALIBRATION

An imaging system includes a focal plane array including an array of pixels. An isothermal diaphragm covers a first portion of the pixels along a periphery of the array and exposing an imaging portion of the pixels. A controller is operatively connected to the focal plane array to read sensor data from the focal plane array, wherein the sensor data includes image data from the imaging portion of the pixels and non-uniformity data from the first portion of the pixels. The controller is operatively connected to the focal plane array to enhance the image data based on the non-uniformity data.