In this paper image quality of two types of compression methods, wavelet based and seam carving based are investigated. A metric is introduced to compare the image quality under wavelet and seam carving schemes. Meyer...In this paper image quality of two types of compression methods, wavelet based and seam carving based are investigated. A metric is introduced to compare the image quality under wavelet and seam carving schemes. Meyer, Coiflet 2 and Jpeg2000 wavelet based methods are used as the wavelet based methods. Hausdorf distance based metric (HDM) is proposed and used for the comparison of the two compression methods instead of model based matching techniques and correspondence-based matching techniques, because there is no pairing of points in the two sets being compared. In addition entropy based metric (EM) or peak signal to noise ration based metric (PSNRM) cannot be used to compare the two schemes as the seam carving tends to deform the objects. The wavelet compressed images with different compression percentages were analyzed with HDM and EM and it was observed that HDM follows the EM/PSNRM for wavelet based compression methods. Then HDM is used to compare the wavelet and seam carved images for different compression percentages. The initial results showed that HDM is better metric for comparing wavelet based and seam carved images.展开更多
Based on explanation of wavelet fractal compression method, the significance of introducing wavelet decomposition into conventional fractal compression method is deeply investigated from the point of theoretical and p...Based on explanation of wavelet fractal compression method, the significance of introducing wavelet decomposition into conventional fractal compression method is deeply investigated from the point of theoretical and practical view. The result of study can be regarded as valuable guidelines for taking advantages of wavelet transform to develop more effective image compression algorithm.展开更多
To utilize residual redundancy to reduce the error induced by fading channels and decrease the complexity of the field model to describe the probability structure for residual redundancy, a simplified statistical mode...To utilize residual redundancy to reduce the error induced by fading channels and decrease the complexity of the field model to describe the probability structure for residual redundancy, a simplified statistical model for residual redundancy and a low complexity joint source-channel decoding（JSCD） algorithm are proposed. The complicated residual redundancy in wavelet compressed images is decomposed into several independent 1-D probability check equations composed of Markov chains and it is regarded as a natural channel code with a structure similar to the low density parity check （LDPC） code. A parallel sum-product （SP） and iterative JSCD algorithm is proposed. Simulation results show that the proposed JSCD algorithm can make full use of residual redundancy in different directions to correct errors and improve the peak signal noise ratio （PSNR） of the reconstructed image and reduce the complexity and delay of JSCD. The performance of JSCD is more robust than the traditional separated encoding system with arithmetic coding in the same data rate.展开更多
In Order to reduce the noise in the images and the physical storage, the wavelet-based image compression technique was applied to PIV processing in this paper. To study the effect of the wavelet bases, the standard PI...In Order to reduce the noise in the images and the physical storage, the wavelet-based image compression technique was applied to PIV processing in this paper. To study the effect of the wavelet bases, the standard PIV images were compressed by some known wavelet families, Daubechies, Coifman and Baylkin families with various compression ratios. It was found that a higher order wavelet base provided good compression performance for compressing PIV images. The error analysis of velocity field obtained indicated that the high compression ratio, even up to 64.1, can be realized without losing significant flow information in PIV processing. The wavelet compression technique of PIV was applied to the experimental images of jet flow and showed excellent performance. A reduced number of erroneous vectors can be realized by varying compression ratio. It can say that the wavelet image compression technique is very effective in PIV system.展开更多
A coding method of speech compression, which is based on Wavlet Transform and Vector Quantization (VQ), is developed and studied. The Wavlet Thansform or Wavlet Packet Thansform is used to process the speech signal, t...A coding method of speech compression, which is based on Wavlet Transform and Vector Quantization (VQ), is developed and studied. The Wavlet Thansform or Wavlet Packet Thansform is used to process the speech signal, then VQ is used to compress the coefficients of Wavlet Thansform, and the entropy coding is used to decrease the bit rate. The experimental results show that the speech signal, sampled by 8 kHz sampling rate and 8 bit quatisation,i.e., 64 kbit/s bit rate, can be compressed to 6 - 8 kbit/s, and still have high speech quality,and the low-delay, only 8 ms.展开更多
文摘In this paper image quality of two types of compression methods, wavelet based and seam carving based are investigated. A metric is introduced to compare the image quality under wavelet and seam carving schemes. Meyer, Coiflet 2 and Jpeg2000 wavelet based methods are used as the wavelet based methods. Hausdorf distance based metric (HDM) is proposed and used for the comparison of the two compression methods instead of model based matching techniques and correspondence-based matching techniques, because there is no pairing of points in the two sets being compared. In addition entropy based metric (EM) or peak signal to noise ration based metric (PSNRM) cannot be used to compare the two schemes as the seam carving tends to deform the objects. The wavelet compressed images with different compression percentages were analyzed with HDM and EM and it was observed that HDM follows the EM/PSNRM for wavelet based compression methods. Then HDM is used to compare the wavelet and seam carved images for different compression percentages. The initial results showed that HDM is better metric for comparing wavelet based and seam carved images.
基金This project is supported by the National Natural Science Foundation of China (No. 69774030) Foundation for University Key Teacher by the Ministry of Education.
文摘Based on explanation of wavelet fractal compression method, the significance of introducing wavelet decomposition into conventional fractal compression method is deeply investigated from the point of theoretical and practical view. The result of study can be regarded as valuable guidelines for taking advantages of wavelet transform to develop more effective image compression algorithm.
文摘To utilize residual redundancy to reduce the error induced by fading channels and decrease the complexity of the field model to describe the probability structure for residual redundancy, a simplified statistical model for residual redundancy and a low complexity joint source-channel decoding（JSCD） algorithm are proposed. The complicated residual redundancy in wavelet compressed images is decomposed into several independent 1-D probability check equations composed of Markov chains and it is regarded as a natural channel code with a structure similar to the low density parity check （LDPC） code. A parallel sum-product （SP） and iterative JSCD algorithm is proposed. Simulation results show that the proposed JSCD algorithm can make full use of residual redundancy in different directions to correct errors and improve the peak signal noise ratio （PSNR） of the reconstructed image and reduce the complexity and delay of JSCD. The performance of JSCD is more robust than the traditional separated encoding system with arithmetic coding in the same data rate.
文摘In Order to reduce the noise in the images and the physical storage, the wavelet-based image compression technique was applied to PIV processing in this paper. To study the effect of the wavelet bases, the standard PIV images were compressed by some known wavelet families, Daubechies, Coifman and Baylkin families with various compression ratios. It was found that a higher order wavelet base provided good compression performance for compressing PIV images. The error analysis of velocity field obtained indicated that the high compression ratio, even up to 64.1, can be realized without losing significant flow information in PIV processing. The wavelet compression technique of PIV was applied to the experimental images of jet flow and showed excellent performance. A reduced number of erroneous vectors can be realized by varying compression ratio. It can say that the wavelet image compression technique is very effective in PIV system.
文摘A coding method of speech compression, which is based on Wavlet Transform and Vector Quantization (VQ), is developed and studied. The Wavlet Thansform or Wavlet Packet Thansform is used to process the speech signal, then VQ is used to compress the coefficients of Wavlet Thansform, and the entropy coding is used to decrease the bit rate. The experimental results show that the speech signal, sampled by 8 kHz sampling rate and 8 bit quatisation,i.e., 64 kbit/s bit rate, can be compressed to 6 - 8 kbit/s, and still have high speech quality,and the low-delay, only 8 ms.
