In this paper, we firstly present a novel interleaver to improve the error correction performance of turbo codes. Secondly, we devise two types of asymmetric turbo codes to optimize the bit error ...rate of both water fall and error floor. Finally, we propose an efficient joint source-channel coding scheme based on unequal error protection technology using asymmetric turbo codes. The proposed scheme can adaptively adopt different coding strategies, different interleavers of turbo codes, various decoding algorithms and appropriate decoding iterative numbers in terms of the different significant levels of image data streams and the varying conditions of estimated channel state information. This scheme can also dynamically adjust the source and channel code rates according to the calculated peak signal to noise ratio of reconstructed images and the estimated channel states. The experimental results show that the proposed scheme can evidently increase the peak signal to noise ratio of the reconstructed images and improve the visual effect of the images but with no additional bandwidth, the scheme is more adaptive and feasible.
The different image block has different sparsity or compressibility in transform domain; in general, the blocks in smooth region have stronger sparsity while those in texture or edge region have ...weaker sparsity. Based on this observation, a novel block DCT based sampling scheme with coefficients random permutations for image compressive sensing has been proposed in this paper. These random permutations make the sparsity of all the sampled blocks more evenly, which results in requiring approximate equal ratio of measurement for well reconstruction of each sampled block. Experimental results demonstrate that our proposed scheme can efficiently enhance the reconstructed image quality or reduce the measurement ratio.
Compressive sensing (CS) is a new efficient framework for sparse signal acquisition, which has been widely used in many application fields, such as multimedia coding and processing, etc. In this ...paper, a novel block-based compressive sensing scheme for robust image compression applications is proposed, where the relative sparsity of image chunks are exploited to effectively allocate sensing resources to different image blocks. The image is split into non-overlapping blocks of fixed size, which are independently represented by compressive sensing in the discrete cosine transform (DCT) domain. The key idea is to assign more sensing resources to the image blocks with rich edge and texture features but less to the image blocks located at smooth regions. Simulation results for standard compression test images demonstrate that the proposed scheme can get significant performance gain in reducing measurement rate and/or enhancing reconstructed image quality.
Compressed Sensing of Images Using Nonuniform Sampling Cheng Zhou; Chengyi Xiong; Ruixue Mao ...
2011 Fourth International Conference on Intelligent Computation Technology and Automation,
2011-March, Volume:
2
Conference Proceeding
Block-based random image sampling using compressed sensing needs a lot of random measurements which increases the complexity of compression process. This paper proposes a novel nonuniform sampling ...method to measure discrete cosine transform coefficients of image blocks. The coefficients in zigzag order are divided into important and unimportant frequency component and are differentiated in sampling process. Taking this advantage, the proposed algorithm makes it possible to achieve remarkable performance gain at the same number of measurements. Experiments have demonstrated the feasibility and advantage of the proposed scheme.
Design for the asymmetric turbo codes Hanxin Wang; Shaoping Chen; Chengyi Xiong ...
2010 The 12th International Conference on Advanced Communication Technology (ICACT),
2010-Feb., Volume:
1
Conference Proceeding
Two types of asymmetric turbo codes are proposed, i.e., the parallel concatenated turbo codes that use the non-identical component encoder with different constraint lengths and mixed types of ...generator polynomials. The proposed schemes can optimize the BER performance of both water-fall region at low SNR and error-floor region at high SNR. The simulation results show the presented asymmetric turbo codes can achieve better performance than the conventional symmetric system over the entire ranges of SNR with a reduced decoding computational complexity.
An efficient locally adaptive wavelet denoising method is proposed by exploiting the correlation among image wavelet coefficients in a sub-band. Firstly, under the rule of Bayesian maximum a ...posteriori (MAP), we investigate Laplacian prior distribution based MAP estimator formula and sub-band adaptive MapShrink threshold. In order to make this threshold locally adaptive, a new stochastic model for wavelet coefficients is presented, in which each coefficient in a sub-band is assumed to be Laplacian with different marginal standard deviation, and these marginal standard deviations are modeled as random variables with high local correlation and thus can be estimated from a local neighborhood. Experiment results demonstrate the effectiveness of the presented algorithm, compared with the state of the art wavelet based image denoising methods
This paper proposes a new image denoising method which exploits spatial correlation among image wavelet coefficients and classification technique. By extending the neighbouring threshold of wavelet ...coefficients for 1D signal to 2D image case, each coefficient in a subband is classified as "large" or "small" category, according to its corresponding neighbouring threshold. Different strategies are implemented to the classified coefficients. Simulation results show that although very simple, the performance of the proposed method can be competitive to the two excellent state of the art denoising algorithms with spatial adaptivity
MQ arithmetic coder has been adopted to achieve entropy coding in the latest image compression standard JPEG2000. which is a bit-level operation with intensive branch and feedback thus becomes a ...serious bottleneck of high speed JPEG2000. In this paper, an efficient fast algorithm for MQ coder was proposed, in which the renormalization process with BYTEOUT was performed in batch fashion instead of gradual iteration as introduced in JPEG2000. Experimental results have proved the validity of this method in decreasing computation complexity.
A novel VLSI architecture based on an improved lifting algorithm, which can be reconfigurable for 5/3 and 9/7 wavelet transforms, is proposed. The improved lifting algorithm, exploiting the ...parallelism of multiplication and addition operations based on the conventional lifting scheme, efficiently reduces the critical path delay. Systolic and the embedded pipeline techniques are adopted to optimize the design of the architecture, which significantly reduces the hardware complexity and power consumption of the design. Moreover, the proposed architecture works in a serial input fashion, with the result that the accessed memory needs only a single read port and a single write port, and can be easily extended to the implementation of a line-based architecture for 2D DWT.
The residue number system (RNS) has computational advantages in addition and multiplication compared with weighted number systems, such as the binary number system (BNS), since operations on residue ...digits are performed independently and these processes can be performed in parallel. Thus they are widely used in digital signal processing etc. Since residue to binary conversion is critical and difficult for the practicality of RNS, in this paper, a novel residue to binary (R/B) conversion algorithm for the restricted moduli set (2/sup n/ -1, 2/sup n/, 2n+1), based on exploring the periodicity of modulo (2/sup n/ /spl plusmn/ 1) operations is presented. A new 2n-bit adder based R/B converter is also proposed. The performance comparison results demonstrate that the new converter is faster and requires less area compared with the others reported in the previous literature.
