The ABCD rule is a simple framework that physicians, novice dermatologists and nonphysicians can use to learn about the features of melanoma in its early curable stage, enhancing thereby the early detection of melanoma. Since the interpretation of the ABCD rule traits is subjective, different solutions have been proposed in literature to tackle such subjectivity and provide objective evaluations to the different traits. This paper reviews the main contributions in literature towards automating asymmetry, border irregularity, color variegation and diameter, where the different methods involved have been highlighted. This survey could serve as an essential reference for researchers interested in automating the ABCD rule.INDEX TERMS Image processing, machine learning, melanoma detection.GUANG YANG received the M.Sc. degree in vision imaging and virtual environments from the Department of Computer Science, University College London, in 2006, and the Ph.D. degree in medical image analysis jointly from the CMIC,