Measurement of local strains in poly-crystalline materials, subjected to relatively large plastic deformation, is a challenging problem. In this paper we report a novel approach for the calculation of local strains at microscopic levels using Electron Backscattered Diffraction measurements, and subsequent use of digital image processing and a simple algorithm. Identical grains, of a fully recrystallized commercial AA1050 sheet, were indexed before and after a tensile strain of 0.262. Normal and shear strains were calculated by estimating the changes in grain shape and in plane rotation. An excellent correlation was obtained between measured in-grain misorientation developments and the estimated in-grain von-Mises equivalent strains.