It is important to extract useful topologiesfrom the solutions to the topology optimization design for structures andcompliant mechanisms. However, checkerboard patterns andintermediate elements in most topology results make a topologicalcontour extraction very difficult. Due to these facts, the elimination ofcheckerboard patterns, the acceptance or rejection of intermediateelements and thecontour extraction of the resultant topology are three mainproblems during the topology extraction process for structures and compliantmechanisms. The factors in forming checkerboard patterns and intermediateelements during the topology optimization process and the existing methods tocircumvent these problems are discussed. Three typical approaches for imageprocessing, those of level set, parametric active contour and edgedetection, are also discussed.