Heng Yao

Shanghai University, Shanghai, Shanghai Shi, China

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Publications (5)3.57 Total impact

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    ABSTRACT: A robust hashing method is developed for detecting image forgery including removal, insertion, and replacement of objects, and abnormal color modification, and for locating the forged area. Both global and local features are used in forming the hash sequence. The global features are based on Zernike moments representing luminance and chrominance characteristics of the image as a whole. The local features include position and texture information of salient regions in the image. Secret keys are introduced in feature extraction and hash construction. While being robust against content-preserving image processing, the hash is sensitive to malicious tampering and, therefore, applicable to image authentication. The hash of a test image is compared with that of a reference image. When the hash distance is greater than a threshold τ1 and less than τ2, the received image is judged as a fake. By decomposing the hashes, the type of image forgery and location of forged areas can be determined. Probability of collision between hashes of different images approaches zero. Experimental results are presented to show effectiveness of the method.
    IEEE Transactions on Information Forensics and Security 01/2013; 8(1):55-63. · 1.90 Impact Factor
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    ABSTRACT: In visual perception, distant objects appear smaller than those close to the observer. To insert an object into an image, properly size a foreign object is difficult, especially when there is no reference object in the same distance. To detect this type of image forgery, we present a perspective-constraint based method, with which the height ratio of two objects in an image can be determined without any knowledge of the camera parameters. Assuming that the camera is held leveled and with negligible tilt, the height ratio can be found merely by a vanishing line of the plane on which both objects of interest is situated. Once the estimated ratio exceeds a tolerable interval, a forged region is identified. Experimental results show efficacy of the method even if the images to be tested have been down-sampled or compressed with a low quality factor.
    IEEE Signal Processing Letters 01/2012; 19:123-126. · 1.67 Impact Factor
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    ABSTRACT: A video fingerprinting that extracts fingerprints from videos and finds other similar ones from a reference database, is used for media indexing, content retrieval and copyright management. In this paper, we attempt to extract spatial and temporal information of a video as its fingerprint by Three- dimension Discrete Cosine Transform (3D-DCT) and apply Locality-Sensitive Hashing (LSH) to search the similar ones in the video fingerprint database. It combines the robustness of coefficients of 3D-DCT with the retrieval efficiency of LSH. This system can yield a high precision rate of 98.25% and a recall rate of 88.78%. Experimental results illustrate that our system outperforms existing methods in copy detection based on fingerprint.
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    ABSTRACT: Copy-move is a common manipulation of digital image tampering. Block matching after feature extraction is mostly applied method to detect this kind of forgery. In this paper, we propose an efficient copy-move detecting scheme with the capacity of some post-processing resistances. The image is divided into fixed-size overlapped blocks, and then non-negative matrix factorization (NMF) coefficients are extracted from list of all blocks. It is worth noting that all the coefficients are quantized before matching, in other words, we could use relatively few data to interpret a sub-image. Besides, we apply lexicographical sorting method to reduce the probability of invalid matching. Lastly we measure the hamming distance of each block pair in the matching procedure, if the distance is shorter than a threshold, we localize them as the tampering areas. Experimental results show the efficacy of our scheme.
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    ABSTRACT: Linear contrast enhancement is a common procedure for expanding or reducing dynamic range of the image gray values. We propose a method to detect global linear contrast enhancement to be used as a technique for digital image authentication. We show that a linear mapping operation introduces periodic artifacts into the histogram, and the period is related to the mapping function. We develop an algorithm to estimate the parameters of a three-section polyline mapping function. Experimental results show effectiveness of the proposed algorithms.
    Wireless Mobile and Computing (CCWMC 2009), IET International Communication Conference on; 01/2010