Abstract: A method and apparatus of the present invention corrects the nonuniformity in the printing density between the printing elements of a thermal print head by first printing across a transparent receiver with each element of the head activated with equal inputs (flat field). The print transmittance values are read from the transparent receiver using, for example, a microdensitometer, and an adjustment factor for each heating element is computed and maintained in storage to be combined with the number of heating pulses assigned to each of the respective heating elements as they perform their normal printing function.