1. A method for correcting a butting artifact in an x-ray image comprising: receiving an x-ray image having a butting artifact, the butting artifact including one or more lines of pixels; calculating multiple intensity shift estimators for each pixel of each line of the butting artifact; calculating a confidence measure for each of the multiple intensity shift estimators; determining an intensity shift value for each pixel of each line of the butting artifact using a multiple hypothesis hidden Markov model (MH-HMM) formulated based on the intensity shift estimators and the confidence intervals subject to a smoothness constraint; and generating a corrected image by adjusting an intensity of each pixel of each line of the butting artifact in the x-ray image based on the intensity shift value determined for that pixel.