Photoelasticity is the only whole-field experimental technique which can analyse both 2-D and 3-D elasticity problems. In digital photoelasticity one gets two phase maps, one corresponding to principal stress direction (isoclinic) and the other corresponding to principal stress difference (isochromatic). The phase maps for both isoclinics and isochromatics are to be unwrapped differently for obtaining continuous phase values. Autonomous phase unwrapping is one of the challenging issues and this paper focuses on recent advances on isochromatic phase map unwrapping. A comparative study of different autonomous phase unwrapping algorithm is done by solving a bench mark problem and a stress frozen slice with cut-outs. The need for domain delimiting in addition to domain masking is brought out while using autonomous phase unwrapping algorithms.