Compressed Sensing Based Image Compression And Encryption Algorithm Optimization And Circuit Design

With the popularity of wireless networks and Internet networks and the development of image acquisition technology,the data transmitted by network is developed from general data to multimedia and big data.In order to improve the flexibility of multimedia applications and the security of data transmission,it is of great significance to design an efficient image compression and encryption algorithm.In this thesis,based on the traditional compression method,where discrete cosine transform(DCT)high frequency components are truncated,an image compression method based on compressed sensing is improved.In this method,the high frequency components are compressed by using compressed sensing because high-frequency components are sparse.This method can avoid the blind-estimation for DCT high frequency components,and reconstruct the low-frequency components and high-frequency components accurately.Simulation experiments show that its average PSNR is improved by at least 0.23dB compared with the traditional method,which means that reconstructed image is similar with the original image.In order to solve the problem that it is required that image blocks with the same size have the same sparsity in Kronecker compressed sensing,an image uniform sparsity scrambling method based on elementary cellular automata is designed and a simple approximation evaluation method is given.The evaluation results show that the uniformed image has good sparse uniformity.And then a Bernoulli random matrix generated by a piecewise linear chaotic mapping method is used to Kronecker compressed encrypted image.The simulation results show that the designed image encryption and compression method can accurately reconstruct the original image,compared with the traditional method,PSNR is improved by 0.73dB when compression rate is 0.25,the correlation coefficient of the compressed encrypted image reduced to less than 0.0097,which means that the proposed encryption and compression method has good performance.Finally,the image compression circuit and the image encryption compression circuit are designed.The Modelsim simulation and FPGA verification are performed.The results show that the designed image compression circuit and image compression encryption circuit consume less hardware resources compared with traditional circuits,and achieve good tradeoff among compression performance,encryption performance and hardware consumption.