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Conventional visual secret sharing schemes generate noise-like random pixels on shares to hide secret images. It suffers a management problem, because of which dealers cannot visually identify each share. This problem is solved by the extended visual cryptography scheme (EVCS), which adds a meaningful cover image in each share. However, the previous(More)
Conventional visual secret sharing (VSS) schemes hide secret images in shares that are either printed on transparencies or are encoded and stored in a digital form. The shares can appear as noise-like pixels or as meaningful images; but it will arouse suspicion and increase interception risk during transmission of the shares. Hence, VSS schemes suffer from(More)
Conventional visual cryptography (VC) suffers from a pixel-expansion problem, or an uncontrollable display quality problem for recovered images, and lacks a general approach to construct visual secret sharing schemes for general access structures. We propose a general and systematic approach to address these issues without sophisticated codebook design.(More)
In this paper, we develop an algorithm to deploy an energy efficient sensor network such that it provides surveillance and target-positioning services. We consider to place K independent sets of sensors on a sensor field. These sets monitor the field in turn and work together when intrusion events occur. The lifetime of the sensor network is therefore(More)
Reducing the pixel expansion and improving the display quality of recovered images are still major issues in visual cryptography schemes (VCSs), particularly for large <i>k</i> and <i>n</i>. Moreover, the development of a systematic and practical approach for threshold VCSs is a challenge. In this paper, a pixel-expansion-free threshold VCSs approach based(More)
— In this paper, we develop a novel algorithm to deploy an energy-efficient wireless sensor network (WSN) for the target-location service that is one of the major applications of sensor networks. Such sensor network has to be designed to achieve complete coverage quality of surveillance and full discrimination for predetermined resolution on the sensor(More)