1. A system for parallel image processing in MR imaging, comprising: a plurality of MR imaging RF coils for individually receiving MR imaging data representing a slice or volume of patient anatomy; an MR imaging system for using the plurality of RF coils for acquiring a corresponding plurality of insubstantially complete image data sets of said slice; and an image data processor comprising at least one processing device conditioned for, deriving a first set of weights for weighted combination of k-space data of said plurality of insubstantially complete image data sets for generating a calibration data set comprising a subset of k-space data of composite image data representing said plurality of image data sets, using said calibration data set in generating a first substantially complete MR image data set, deriving the parameters of a probability distribution in response to said first set of weights and said first MR image data set and deriving a second set of weights and second substantially complete MR image data set together using said probability distribution.