1. A method for reconstructing an actual image from sensitivity encoded magnetic resonance imaging (MRI) data capable of being represented in a frequency domain, the frequency domain comprising at least a phase-encoding direction and a frequency-encoding direction, the phase-encoding and frequency-encoding directions corresponding to a first spatial dimension and a second spatial dimension, respectively, the method comprising: acquiring an undersampled MRI data set undersampled in at least the phase-encoding direction; determining reconstruction coefficients of the undersampled MRI data set, wherein the reconstruction coefficients have values that vary across at least the second spatial dimension, which corresponds to the frequency-encoding direction, wherein variation of the values of the reconstruction coefficients is based on variation of coil sensitivities; determining a reconstructed MRI data set by combining the reconstruction coefficients and the undersampled MRI data set; determining a complete MRI data set by combining the undersampled MRI data set and the reconstructed MRI data set; and outputting at least a portion of the complete MRI data set to an output device configured for display or onto a non-transitory computer readable medium.