Optical holographic interferometry (HI) is realized by two well-known techniques: double exposure holographic interferometry (DEHI) and real-time holographic interferometry (RTHI). However, the digital version of HI is typically realized numerically by DEHI. The main problem in digital implementation of RTHI is the lack of commercially available cameras and spatial light modulators with the same pixel size. This mismatch results in lateral and transversal magnifications of an object wavefront reconstruction. In real-time digital HI the reconstruction of an object in an initial state has to be superimposed on top of the loaded object. In this work, we present and analyze five approaches to overcome the mismatch problem, and the performance of these procedures is numerically quantified and compared. The experimental suitability of these approaches is investigated.