Passive Millimeter Wave Super-resolution Imaging Technology

Due to the passive receiver of the object radiation of millimeter wave energy, passive millimeter wave imaging system has a strong concealment. Furthemore, the imaging system has all-weather detection capability for strong penetrating power transmission in the harsh environment. The passive millimeter wave imaging technology has been widely used in remote sensing, navigation, security and other fields for these features. However, the passive millimeter wave imaging system always has low—ass filtering effect due to the finite size of the antenna and the underlying diffraction limits. Hence, acquired images have poor resolution.In practical situation,the quality of images could be improved by ameliorating hardware conditions of imaging system, but this way is technically difficult and costly. Need to seek alternative methods, such as the use of image restoration technology to recover the millimeter-wave images, enhance image resolution.It is found that the POCS algorithm has a perfect capacity to expand spectrum to adapt to the recovery in the passive millimeter wave images with the the analysis and simulation of the traditional image restoration algorithm and the super-resolution image restoration algorithm. Through the discovery of the deficiencies of the POCS algorithm in passive millimeter wave image restoration, an improved POCS algorithm has been proposed. The simulation results show that the algorithm can achieve super-resolution and good low-frequency recovery capabilities, and has faster convergence rate than conventional POCS algorithm, adapted to the passive millimeter wave imaging system.Finally, on the basis of the analysis of the existing image restoration algorithm using the Fourier domain and wavelet domain threshold contraction, a new Fourier Wavelet thresholding shrinkage image restoration algorithm is proposed and given the algorithmthreshold selection method. The experiments show that the algorithm has a strong noise immunity and can effectively eliminate the image of the ring ripple in the recovery process, enhance the resolution of images.