Zhenjun Tang

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This paper designs an efficient image hashing with a ring partition and a nonnegative matrix factorization (NMF), which has both the rotation robustness and good discriminative capability. The key contribution is a novel construction of rotation-invariant secondary image, which is used for the first time in image hashing and helps to make image hash(More)
The invariance relation existing in the non-negative matrix factorization (NMF) is used for constructing robust image hashes in this work. The image is first re-scaled to a fixed size. Low-pass filtering is performed on the luminance component of the re-sized image to produce a normalized matrix. Entries in the normalized matrix are pseudo-randomly(More)
Motivated by the image rescaling estimation method proposed by Gallagher (<i>2nd Canadian Conf. Computer &amp; Robot Vision</i>, 2005: 65-72), we develop an image rotation angle estimator based on the relations between the rotation angle and the frequencies at which peaks due to interpolation occur in the spectrum of the image's edge map. We then use(More)
Encryption is an efficient way to protect the contents of digital media. Arnold transform is a significant technique of image encryption, but has weaknesses in security and applications to images of any size. To solve these problems, we propose an image encryption scheme using Arnold transform and random strategies. It is achieved by dividing the image into(More)
Image hash is a content-based compact representation of an image for applications such as image copy detection, digital watermarking, and image authentication. This paper proposes a lexicographical-structured framework to generate image hashes. The system consists of two parts: dictionary construction and maintenance, and hash generation. The dictionary is(More)
Image encryption is a useful technique for many applications, such as image content protection, image authentication, pay-TV and data hiding. In this paper, we propose an efficient image encryption algorithm with block shuffling and chaotic map. The proposed algorithm divides an input image into overlapping blocks, shuffles image blocks to make initial(More)
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(More)
Convex hull is widely used in computer graphic, image processing, CAD/CAM and pattern recognition. In this work, we derive some new convex hull properties and then propose a fast algorithm based on these new properties to extract convex hull of the object in binary image. It is achieved by computing the extreme points, dividing the binary image into several(More)