Most of previous image mosaicking techniques deal with stationary images that do not contain moving objects. But these moving objects cause serious errors on global motion estimation which is the core process of the image mosaicking since the global motion is estimated biased by local motions due to moving objects. There are some proposed techniques to effectively eliminate local motions and get precise global motion parameters but they have their own drawbacks, respectively.
In this paper a contour-based approach for mosaicking images that contain moving objects in them is presented. First, we extract contours from each image to be mosaicked. And then we estimate initial global motion. The key task of our work is how to eliminate local motions and obtain a precise global motion between two input images. To do this, we use three kinds of consistency check algorithm. Shape similarity consistency, scale consistency, and rigid transformation consistency. In these check processes, local movings are detected due to their motion vectors far different from the dominant one and removed in an iterative way. Besides, since we use contour information for image mosaicking, our approach is robust against the global gray level change between input images. Experimental results demonstrate the performance of our algorithm.
In this paper, we propose a real-time video watermarking algorithm for MPAG streams. Watermarking Technique has been studied as a method to hide secret information into the signals so as to discourage unauthorized copy or attest the origin of the media. In the proposed algorithm, we take advantage of compression information of MPEG bistreams to embed the watermark into I-, P-, and B-Picture. The experimental results show that the proposed watermarking technique results almost invisible difference between watermarked MPEG video and original MPEG video, and reduces the processing time. Moreover, it shows robustness against a variety of attacks as well.
Full search block matching motion estimation requires a very large amount of computing power. To overcome this problem, many fast search algorithms have been proposed. But, all these algorithms do not satisfy both matching error performance and real time property at the same time. This paper proposes a novel fast block matching algorithm using temporal correlation and center biased behavior of motion vector. In proposed algorithm, we modify new three-step search algorithm to combine technique for temporal correlation of motion vectors and center biased assumption. In real video sequences, there are many overlapped motion vectors between adjacent frames. Thus, by finding these duplicated motion vectors with a simple search rule, the proposed algorithm dramatically reduces the computational amount with low quality degradation.
This paper presents a robust and efficient scene-based video watermarking method using visual rhythm in compressed domain. A visual rhythm is a two dimensional abstraction of the entire three dimensional video contents obtained by cutting through the video sequence across the time axis or by sampling a certain group of pixels in consecutive video frames. Knowing that scene changes can be easily detected using visual rhythm and video sequences are conveniently edited at the scene boundaries, such scene-based watermark embedding process is a logical choice for video watermarking. Temporal spread spectrum can be achieved by applying spread spectrum methods to visual rhythm. Additive Gaussian noise, low-pass filtering, median filtering and histogram equalization attacks are simulated for all frames. Frame sub-sampling is also simulated as a typical video attack. Simulation results show that proposed algorithm is robust and efficient against these attacks.