1. A method for automatically calibrating a machine vision system including a color camera having output channels for generating a video signal and a computer having a memory wherein the system introduces an offset to the video signal for each channel, the method comprising the steps of: measuring the offset for each channel; generating a first set of calibration data based on the offsets; providing a calibration target having a monotone region of known reflectance; utilizing the color camera to generate a target image containing the target with the monotone region for each of the output channels; measuring an output of each of the output channels during the step of utilizing to obtain output measurements; computing a second set of calibration data from the output measurements and the first set of calibration data; and storing the second set of calibration data in the memory, the second set of calibration data being applied by the computer to each subsequent image acquired by the color camera on a pixel-by-pixel basis to obtain a color-corrected image.