Detection of Seam Carving and Localization of Seam Insertions in Digital Images

"Seam carving" is a recently introduced content aware image resizing algorithm. This method can also be used for image tampering. In this paper, we explore techniques to detect seam carving (or seam insertion) without knowledge of the original image. We employ a machine learning based framework to distinguish between seam-carved (or seam-inserted) and normal images. It is seen that the 324-dimensional Markov feature, consisting of 2D difference histograms in the block-based Discrete Cosine Transform domain, is well-suited for the classification task. The feature yields a detection accuracy of 80% and 85% for seam carving and seam insertion, respectively. For seam insertion, each new pixel that is introduced is a linear combination of its neighboring pixels. We detect seam insertions based on this linear relation, with a high detection accuracy of 94% even for very low seam insertion rates. We show that the Markov feature is also useful for scaling and rotation detection.