Abstract: A method of calibrating an image sensor having an array of pixel sensor sites, and an area light source having a corresponding array of pixel emission sites, comprising the steps of:a. measuring the output of the light source in a first region with a radiometer to generate an absolute measured light value;b. identifying a first region of the image sensor corresponding to the first region of the light source;c. successively positioning, reading out, and stepping the image sensor with respect to the light source to create a first file of pixel values representing one pixel in the first region of the sensor that has read every pixel in the first region of the source, and a second file of pixel values representing one pixel in the source that has been read by every pixel in the first region of the sensor;d. calibrating each pixel in the first region of the light source using the absolute measured light value and the pixel values in the first file;e.