Photoelectron emission microscopy (PEEM) in combination with magnetic circular dichroism in soft X-ray absorption (XMCD) allows the layer-resolved microscopic imaging of magnetic domains. This is applied for the study of ultrathin epitaxial Co/Cu/Ni/Cu(0 0 1) trilayers. At about 1.9 atomic monolayers (ML) Co on 4 ML Cu/15 ML Ni a spin-reorientation transition of the Co layer between out-of-plane and in-plane, accompanied by a transition from collinear to non-collinear alignment between Co and Ni is observed.