The problem of image retrieval is much more challenging than that of text retrieval since significant features for representing and searching an arbitrary image vary with the image content. In this work, we focus on processing images containing landmarks which are easily recognizable by human users. Our observations show that through the use of proper techniques for skyline extraction, the retrieval task of landmark images can be feasible. Specifically, after conducting edge detection on an image, an approach which works in the similar fashion as depth first search is proposed to extract the corresponding skyline precisely. In addition to theoretical analysis of relevant issues, empirical studies show that our approach is advantageous to be utilized in practical applications due to its high efficiency, effectiveness and scalability.