1. A method for generating MRI images with reduced aliasing artifacts in either non-parallel or parallel MRI, comprising: electronically reconstructing a series of images using patient image data obtained from a patient MRI image data set by iteratively cycling through different estimated values of phase gradients in at least two dimensions; and electronically selecting an image from the reconstructed images as having a lowest artifact level, wherein the electronically reconstructing step comprises, for a respective image slice, generating a first series of images using different possible phase gradient values along a frequency encoding direction and a second series of images using different possible values of phase gradients along a phase-encoding direction; the method further comprising: generating 1D image signal profiles associated with the reconstructed first and second series of images; and multiplying the 1D image signal profiles by a respective sigmoid-function weight to generate sigmoid-weighted signals, wherein the electronically selecting step is carried out using the sigmoid-weighted signals to identify phase error patterns.