1. An MRI image data signal post-processing method for generating high-resolution DWI images from multi-shot interleaved MRI pulse sequences, without relying on external navigator echoes, comprising: programmatically estimating motion induced phase variations and position changes among multiple segments of acquired DWI image data inherently using parallel image reconstruction; programmatically incorporating (i) shot-to-shot phase and position variations from the estimated motion induced phase variations and position changes and (ii) defined coil sensitivity profile data into a mathematical model that can jointly calculate magnitude-value source density signals that overlap in acquired uncorrected interleaved DWI image data to generate corrected DWI image data; and programmatically generating high-resolution DWI images based on the corrected data to thereby generate images free from aliasing artifacts.