Using a photoelectron emission microscope (PEEM), we demonstrate spin-resolved electron spectro- scopic imaging of ultrathin magnetic Co films grown on Cu (100). The spin-filter, based on the spin- dependent reflection of low energy electrons from a W(100) crystal, is attached to an aberration corrected electrostatic energy analyzer coupled to an electrostatic PEEM column. We present a method for the quantitative measurement of the electron spin polarization at 4 x 10³ points of the PEEM image, simultaneously. This approach uses the subsequent acquisition of two images with different scattering energies of the electrons at the W(100) target to directly derive the spin polarization without the need of magnetization reversal of the sample.