Terahertz Imaging System Using Adaptive DCT-based Image Denoising

The possibility of overcoming some hardware limitations resulting in low quality of terahertz images is considered. The set of images obtained at different distances from the source of terahertz radiation at frequency 0.1 THz is studied. It is shown that the noise in these images is of mixed type and has quite high level of spatial correlation. A fully automatic denoising method based on the use of discrete cosine transform with spatially adapted spectrum is proposed. It is shown that despite initially low spatial resolution of terahertz images and intensive noise, the proposed denoising method provides good noise reduction with good preservation of edges and details, which allows to noticeably enhance the quality of these images.