A new DIA (digital image analysis) oriented method for the polymer blend morphology analysis was developed. The particles seen on SEM (scanning electron microscopy) pictures of the two-phase blends are considered as ellipses rather than circles, so that to be dealt with are their asphericity and orientation. Moreover, replacement of the particle patterns of complex shape by effective ellipses significantly simplifies calculation of such characteristics of the blend morphology as center-to-center (CC) and surface-to-surface (SS) interparticle distance distributions. With the help of a DIA computer program designed on the basis of the proposed algorithms, a series of SEM pictures for polyamide 6/polysulfone blends were analyzed, and new regularities of the blend morphology evolution during mixing were revealed. The changes in the CC and SS interparticle distance distributions, particle orientation distribution, and particle asphericity-size correlation were first characterized quantitatively.