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A VECTOR QUANTIZATION BASED APPROACH FOR CFA DATA COMPRESSION IN WIRELESS ENDOSCOPY CAPSULE

Journal of Electronics(China) 2008年第6期25卷 834-839页

作者： Li Xiaowen Li Guolin Xie Xiang Wang Zhihua Department of Electronic Engineering Tsinghua University Beijing 100084 China Institute of Microelectronics Tsinghua University Beijing 100084 China

A novel approach for near-lossless compression of Color Filtering Array (CFA) data in wireless endoscopy capsule is proposed in this paper. The compression method is based on pre-processing and vector quantization. First, the CFA raw data are low pass filtered and rearranged during pre-processing. Then, pairs of pixels are vector quantized into macros of 9 bits by applying block par-tition and index mapping in succession. These macros are entropy compressed by Joint Photographic Experts Group-Lossless Standard (JPEG-LS) finally. The complex step of codeword searching in Vector Quantization (VQ) is avoided by a predefined partition rule, which is suitable for hardware imple-mentation. By control of the pre-processor and VQ scheme, either high quality compression under un- filtered case or high ratio compression under filtered case can be realized, with the average Peak Sig-nal-to-Noise Ratio (PSNR) more than 43dB and 37dB respectively. Compared with the state-of-the-art method and the previously proposed method, our compression approach outperforms in compression performance as well as in flexibility.

关键词： Pre-processing Vector Quantization (VQ) block partition Index mapping Joint Pho-tographic Experts Group-Lossless Standard (JPEG-LS)

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A block Mean Insertion and Dual Stego Generation Based Embedding Strategy

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Journal of Computer and Communications 2021年第3期9卷 70-87页

作者： Md. Habibur Rahman A. H. M. Kamal Dept. Computer Science and Engineering Jatiya Kabi Kazi Nazrul Islam University Mymensingh Bangladesh Department of Computer Science and Engineering Jatiya Kabi Kazi Nazrul Islam University Mymensingh Bangladesh

In reversible data hiding, pixel value ordering is an up-to-the-minute research idea in the field of data hiding. Secret messages are embedded in the maximum or the minimum value among the pixels in a block. Pixel value ordering helps identify the embeddable pixels in a block but suffers from fewer embedding payloads. It leaves many pixels in a block without implanting any bits there. The proposed scheme in this paper resolved that problem by allowing every pixel to conceive data bits. The method partitioned the image pixels in blocks of size two. In each block, it first orders these two pixels and then measures the average value. The average value is placed in the middle of these two pixels. Thus, the scheme extends the block size from two to three. After applying the embedding method of Weng et al., the implantation task removed the average value from the block to reduce its size again to two. These two alive pixels are called stego pixels, which produced a stego image. A piece of state information is produced during implanting to track whether a change is happening to the block’s cover pixels. This way, after embedding in all blocks, a binary stream of state information is produced, which has later been converted to decimal values. Thus, image data were assembled in a two-dimensional array. Considering the array as another image plane, Weng et al.’s method is again applied to embed further to produce another stego image. Model validation ensured that the proposed method performed better than previous work in this field.

关键词： Reversible Data Hiding Stego Image Multilayer Embedding block partition Embedding Payload

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Depth distribution of Moho and tectonic framework in eastern Asian continent and its adjacent ocean areas

Depth distribution of Moho and tectonic framework in eastern...

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中国科学院地质与地球物理研究所2003学术年会

作者：滕吉文曾融生闫雅芬张慧 Institute of Geology and Geophysics Chinese Academy of Sciences Institute of Geophysics Chinese Seismological Bureau

With the results of interpretation of seismic sounding profiles acquired in the past 30 years in the continent of China and its adjacent countries and ocean regions,such as Russia,Kazakhstan, Japan,India,Pakistan,Philippine ocean basin,Pacific and Indian Ocean,we compiled a 2D Moho distribution map for the continent and its adjacent areas of eastern *** the features of depth distribution and undulation of Moho,it is suggested that the eastern Asian region can be divided into 18 gradient belts with different sizes,18 crustal blocks,20 sediment basins and depression *** depth of Moho varies smoothly in each block,while the boundary(separating different blocks) delineates the abrupt variation of Moho ***,some subjects,such as oregen and sediment basin,fault system and rift,plate boundary,ocean-continent coupling and tectonic framework,are discussed based on the distribution gradient belts and block partition features of Moho depth in the eastern Asia and its adjacent regions.

关键词： Moho block partition sediment basin boundary field effect eastern Asian continent

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