1. A method for phase contrast magnetic resonance (MR) imaging with speed encoding, comprising: operating an MR data acquisition unit according to an MR data acquisition sequence wherein nuclear spins in an examination subject are excited, and MR signals are acquired therefrom in at least one time period, with raw data representing said MR signals being acquired in each time period for a plurality of MR images, with said plurality of MR images comprising a reference MR image with flow compensation and at least one MR image with speed encoding; providing said raw data to an image reconstruction computer and, in said image reconstruction computer, determining a plurality of matrices for each time period of said at least one time period such that the sum of said plurality of matrices is characterized by a pixel matrix with a plurality of matrix elements comprising matrix elements that represent pixel values for said reference MR image and other matrix elements representing pixel values for said at least one MR image with speed encoding, and such that a first matrix among said plurality of matrices fulfilling a predetermined first condition; using said plurality of matrices to reconstruct an image of the examination subject; and making said image of the examination subject available in electronic form at an output of said image reconstruction computer.