1. A method of calibrating a dual energy digital radiography system, utilizing a radiation source, a detector array responsive to radiation of at least two different energies spaced from the source to accommodate the placement of an object in a space between the source and detector array, scanning means for effecting relative scanning motion between the detector array and an object when said object is located in said object space, said calibration method comprising the steps of; (a) scanning a multiplicity of thicknesses of basis materials to create a matrix of low and high energy pixel data; (b) performing a regression on said matrix of low and high energy pixel data to derive at least one low energy coefficient vector and at least one high energy coefficient vector; (c) transforming said at least one low energy and at least one high energy coefficient vectors to low and high energy gain functions; (d) scanning an examination object to create low and high energy image data; (e) combining said low and high energy image data with said low and high energy gain functions to create corrected low and high energy image data.