Duplicate Object Detection for Digital Image Authentication

Digital Image Authentication has become a very important research area. Digital images can be altered easily using freely available image editing softwares. Many a times, it becomes impossible to ascertain the authentic image from the tampered image. These tampered images can be created by using graphical softwares, or can be manipulated simply by changing the content and context of the image. This creates problems for authentication of the digital image. Tampering a digital image by duplicating an object or a particular segment within the same image is one of the most prominent and easily done forgeries. It is known as copy-move tampering. It is very difficult to find out the duplicated objects or segments within the given image. In this paper, we study the recently developed major approaches to detect duplicate objects in digital images. Initially, the process of digital image tampering is explained. Subsequently, we analyze some of recently developed algorithms like Discrete Wavelet Transform (DWT), Singular Value Decomposition (SVD), FourierMellin Transform (FMT), Discrete Cosine Transform (DCT), Principal Component Analysis (PCA), Scale Invariant Features Transform (SIFT), Wavelets and Logpolar Mapping, Block Artifact Grid (BAG), Speedup Robust Features (SURF) etc. for detecting duplicate object within the same image. Preliminary investigations show that different algorithms have different domains of tampering detection and have different merits and demerits. The decision about the content authenticity is complex and can be better established by interpreting the results obtained by applying a set of these methods.