Restoration of integrated circuit terahertz image based on wavelet denoising technique and the point spread function model

•A novel method for terahertz image restoration using wavelet denoising with point spread function model.•The imaging resolution increases with higher frequency; however, the higher the frequency, the lower the SNR of the THz image.•The wavelet denoising method is beneficial to reduce the high frequency noises, which shows a great performance of the image restoration.•The combination of rigrsure threshold and db5 wavelet basis delivers the best IC image. In recent years, terahertz (THz) imaging technology has attracted much attention in the detection of the integrated circuit (IC). However, limited by the hardware of the imaging system, THz images often contain a significant amount of noise, which impairs the quality of the image details. The THz image is also degraded due to the long wavelength. In this study, we propose a novel method for THz image restoration. We first apply a wavelet denoising technique to process the THz time-frequency signal. The point spread function (PSF) is then mathematically modeled to restore the details of the IC image, as the degradation of the THz image can be regarded as the convolution process of the object equation and PSF. Finally, we compare the performance between the restored THz images before and after wavelet denoising. The results demonstrate that the restored image after denoising performs better in peak signal-to-noise ratio and visual improvements, proving the practicability and precision of our proposed method.