Terahertz Imaging Based on Morphological Reconstruction

Terahertz (THz) imaging technology is a developing and promising candidate for biological diagnosis, security inspection, and semiconductor wafer examination, due to the low photon energy, the high transparency, and the fingerprint properties of the THz radiation. However, a major encountered bottleneck is the degradation of image quality caused by the power fluctuation of THz source, interference phenomenon, complex environment, and so on. In this paper, we present the mathematical morphology for THz imaging to improve the image quality, taking advantage of morphological reconstructions. Based on the original THz image of a paper with some letters taken from our continuous THz imaging system, the visibility of objects has been successfully enhanced with the suppression of complex background and improvement of peak signal-to-noise ratio using morphological reconstruction. Moreover, morphological reconstruction with proper structuring element parameter was then performed to a THz image of fresh rat cerebral tissue. It presents a satisfactory result with clearer edges and suppressions of the interference fringes and noises. It is suggested that THz imaging based on morphological reconstruction opens a pathway towards automatic techniques for denoising, recognitions, and segmentations in THz biomedical imaging.