Recently more and more researches in the information security field have been focused on the digital image zero-watermarking technology which is an important mean for protecting the digital multimedia copyright. In this paper, first the research background of image zero-watermarking is analyzed; and then the typical algorithms are presented and discussed; finally the performance of these typical algorithms are analyzed and experimented.

As the first step in 3D point cloud process, registration plays an critical role in determining the quality of subsequent results. In this paper, an initial registration algorithm of point clouds based on random sampling is proposed. In the proposed algorithm, the base points set is first extracted randomly in the target point cloud, next an optimal corresponding points set is got from the source point cloud, then a transform matrix is estimated based on the two sets with least square methods, finally the matrix is applied on the source point cloud. Experimental results show that this algorithm has ideal precision as well as good robustness.

False alarm and missing alarm are two of the most important performances for multiple bits watermarking systems. In this paper, we study false alarm and missing alarm probability models when multiple watermarks or multiple bits watermarks embedded. We derive the false alarm and missing alarm probability models for dither modulation from the detection principle of the detectors. The theoretical results are compared with the experimental results obtained in the case of random work and watermark, and the comparison validates the accuracy of the models, and it also shows that random work and watermark have little influence on the false alarm and missing alarm probabilities, and this is the same with the situation when only one bit watermark is embedded by DM.

The Point Cloud Library (PCL) is a good tool for point cloud data processing. In this paper, a method of 3D reconstruction for rock mass based on PCL is introduced, where hardware choosing, parallel computing, PCL, and edge extraction are analyzed and used in order to realize a better reconstruction effect, including both precision and speed. The reconstruction results can be used in engineering calculation.

The additive noise is a common type of noise in signal processing. Although its existence does not depend on the input signal, it has a great interference on the useful signal. In the field of information hiding, additive noise and de-noising is also an important research direction and is crucial for the security. In this paper, different information hiding methods of linear carrier are analyzed and the pros and cons of each way are compared. Beside this, a deep research is carried on the effect of Gaussian noise and Salt & Pepper noise on each method. The simulation comparison shows that additive noise has a great influence on information hiding, and under the same noise intensity, the method of hiding information based on the difference of concave and convex square waves has stronger robustness.