Search

The premise of effective use of high-resolution remote sensing (HRRS) images is that the data integrity and authenticity of HRRS images must be guaranteed. This paper proposes a new subject-sensitive hashing algorithm for the integrity authentication of HRRS images. This algorithm takes AGIM-net (Attention Gate-based improved M-net) proposed in this paper to extract the subject-sensitive features of the HRRS images, and uses Principal Component Analysis (PCA) based method to compress and encode the extracted features. AGIM-net is an improved U-net based on attention mechanism, adding multi-scale input in the encoder stage to extract rich image features; adding multi-scale output in the decoder stage, and suppressing the features irrelevant to the subject through Attention Gate to improve the robustness of the algorithm. Experiments show that the proposed algorithm has improved robustness compared with existing algorithms, and the tamper sensitivity and security are basically equivalent to the existing algorithms. [ABSTRACT FROM AUTHOR]

Low density parity check (LDPC) codes enjoy the good properties of approaching the Shannon limit, and its practical application is of great significance. In this paper, the decoding algorithm of LDPC codes for eight-phase-shift keying modulation is particularly studied, and the specific methods of the maximum average mutual information quantisation are analysed and deduced. With this method to quantify the initial message, the variable messages and check messages are converted into integers when each iteration has been finished, and then the min-sum decoding algorithm based on integer arithmetic is implemented. Simulation results demonstrate that the performance of the min-sum decoding algorithm with maximum average mutual information quantisation is close to that of the high-precision floating-point sum-product decoding algorithm. Meanwhile, It is convenient for hardware implementation since all the variables in the algorithm are fixed-length integers. Although the bit error rate is slightly worse than that of the sum-product decoding algorithm, the decoding time consumption is greatly reduced. [ABSTRACT FROM AUTHOR]