Feature-Based Adaptive Block Partition Method for Data Prefetching in Streamline Visualization

Author(s):  
Yumeng Guo ◽  
Wenke Wang ◽  
Sikun Li
Symmetry ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 49 ◽  
Author(s):  
Shaowei Weng ◽  
Yi Chen ◽  
Wien Hong ◽  
Jeng-Shyang Pan ◽  
Chin-Chen Chang ◽  
...  

After conducting deep research on all existing reversible data hiding (RDH) methods based on Alattar’s integer transform, we discover that the frequently-used method in obtaining the difference value list of an image block may lead to high embedding distortion. To this end, we propose an improved Alattar’s transform-based-RDH-method. Firstly, the irregular block partition method which makes full use of high correlation between two neighboring pixels is proposed to increase the embedding performance. Specifically, each image block is composed of a center pixel and several pixels surrounding this center pixel. Thus, the difference value list is created by using the center pixel to predict each pixel surrounding it. Since the center pixel is highly related to each pixel surrounding it, a sharp difference value histogram is generated. Secondly, the mean value of an image block in Alattar’s integer transform has embedding invariance property, and therefore, it can be used for increasing the estimation performance of a block’s local complexity. Finally, two-layer embedding is combined into our scheme in order to optimize the embedding performance. Experimental results show that our method is effective.


2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Zeyid T. Ibraheem ◽  
Md. Mijanur Rahman ◽  
Yousef Fazea ◽  
Kawakib K. Ahmed

AbstractOrthogonal Frequency Division Multiplexing (OFDM) is a potential transmission approach for high capacity communication systems. Despite the many advantages of OFDM, the major downside is the high peak-to-average power ratio (PAPR) which increases the system complexity, reduces the efficiency of the system, causes degradation in BER performance, and makes OFDM sensitive to nonlinear distortion in the transmission. Various methods have been proposed to deal with the PAPR problem, including the partial transmit sequence (PTS) that has attracted considerable attention. Hence, this paper presents a hybrid approach combining an enhanced PTS technique with Mu-Law companding. The PTS technique was enhanced through improving its sub-block partitioning scheme, where the enhanced partitioning scheme consolidated a conventional interleaved partitioning into an adjacent partitioning scheme. This incorporation of Mu-Law characteristic in time domain for PAPR reduction in OFDM essentially enhances the PAPR reduction performance, based on using numerical simulation results. Consequently, though the pseudorandom sub-block partition method obtains better PAPR reduction more than the other sub-block partition schemes (interleaved and adjacent) of ordinary PTS, it is quite difficult to be designed. The findings show that the enhanced PTS technique with Mu-Law companding, while maintaining low computational complexity, performs significantly better than the pseudorandom partitioning PTS on various types of modulation formats and subcarriers.


2015 ◽  
Vol 8 (2) ◽  
pp. 247-256
Author(s):  
Fang Lv ◽  
Junheng Huang ◽  
Yuliang Wei ◽  
Bailing Wang

Sign in / Sign up

Export Citation Format

Share Document