A general non-parametric technique is proposed for the analysis of a complex multimodal feature space and to delineate arbitrarily shaped clusters in it. The basic computational module of the technique is an old pattern recognition procedure: the mean shift. For discrete data, we prove the convergence of a recursive mean shift procedure to the nearest stationary point of the underlying density function and, thus, its utility in detecting the modes of the density. The relation of the mean shift procedure to the Nadaraya-Watson estimator from kernel regression and the robust M-estimators; of location is also established. Algorithms for two low-level vision tasks discontinuity-preserving smoothing and image segmentation - are described as applications. In these algorithms, the only user-set parameter is the resolution of the analysis, and either gray-level or color images are accepted as input. Extensive experimental results illustrate their excellent performance.

Mean shift: a robust approach toward feature space analysis

Digital watermarking is a key ingredient to copyright protection. It provides a solution to illegal copying of digital material and has many other useful applications such as broadcast monitoring and the recording of electronic transactions. Now, for the first time, there is a book that focuses exclusively on this exciting technology. Digital Watermarking covers the crucial research findings in the field: it explains the principles underlying digital watermarking technologies, describes the requirements that have given rise to them, and discusses the diverse ends to which these technologies are being applied. As a result, additional groundwork is laid for future developments in this field, helping the reader understand and anticipate new approaches and applications.

Digital Watermarking

/pdf/a-break-in-the-clouds-towards-a-cloud-definition-svovsw1r5a.pdf

A Break in the Clouds: Towards a Cloud Definition

A morphable model for the synthesis of 3D faces

In this paper, we define and explore proofs of retrievability (PORs). A POR scheme enables an archive or back-up service (prover) to produce a concise proof that a user (verifier) can retrieve a target file F, that is, that the archive retains and reliably transmits file data sufficient for the user to recover F in its entirety.A POR may be viewed as a kind of cryptographic proof of knowledge (POK), but one specially designed to handle a large file (or bitstring) F. We explore POR protocols here in which the communication costs, number of memory accesses for the prover, and storage requirements of the user (verifier) are small parameters essentially independent of the length of F. In addition to proposing new, practical POR constructions, we explore implementation considerations and optimizations that bear on previously explored, related schemes.In a POR, unlike a POK, neither the prover nor the verifier need actually have knowledge of F. PORs give rise to a new and unusual security definition whose formulation is another contribution of our work.We view PORs as an important tool for semi-trusted online archives. Existing cryptographic techniques help users ensure the privacy and integrity of files they retrieve. It is also natural, however, for users to want to verify that archives do not delete or modify files prior to retrieval. The goal of a POR is to accomplish these checks without users having to download the files themselves. A POR can also provide quality-of-service guarantees, i.e., show that a file is retrievable within a certain time bound.

PORs: Proofs of Retrievability for Large Files

Novel multi-centroid, multi-run sampling schemes for K-mediods-based algorithms

An incremental multi-centred, multi-run sampling scheme for K-medoids-based algorithms

Radio Frequency Identification (RFID) is a radio communication technique. It identifies specific targets and acquires related data from the backend database by using radio frequency signal and no physical touch needed. Because of its advantages of low cost and remote identity recognition, RFID has been widely used in many applications. In 2011, Bassil et al. proposed an RFID authentication protocol based on physically unclonable functions. In this paper, we demonstrate that this protocol still insecure against forgery reader attack, de-synchronization attack and physical analytic cloning attack.

Pitfalls in an Ultra-Lightweight Authentication Protocol for Low-Cost RFID

In this paper, we propose a novel scheme of data hiding for halftone image which is extended from Fu and Oscar's DHSPT method (data hiding smart pair toggling), it is named as DHADPT (data hiding by absolute difference pair toggling). In this method, we embed the binary data into the halftone image with reference to the original multitone image by evaluating the absolute difference between the neighboring gray-level pixels. The location with minimum sum of the absolute differences of the eight neighboring locations will be the candidate to hide bit data. Experimental results prove its superiority to the original DHSPT method (with higher modified peak signal-to-noise ratio [MPSNR]).

Halftone Image Data Hiding with Reference to Original Multitone Image

Recently, Wu et al. proposed a time-bound hierarchical key assignment (TBHKA) scheme which supports discrete time periods. In their scheme, it fused RSA and pairing-based cryptosystems and is provably secure. In this paper, we demonstrate a weakness of Wu et al.'s TBHKA scheme, ie. a collusion attack. Any two users can collude to compute an encryption key to access some class in an un-subcribing time period.

Jeng-Shyang Pan

Papers

Novel multi-centroid, multi-run sampling schemes for K-mediods-based algorithms

An incremental multi-centred, multi-run sampling scheme for K-medoids-based algorithms

Pitfalls in an Ultra-Lightweight Authentication Protocol for Low-Cost RFID

Halftone Image Data Hiding with Reference to Original Multitone Image

Security Analysis of a Time-Bound Hierarchical Key Assignment Scheme