Until recent years, terahertz waves were an undiscovered, or most importantly, an unexploited area of electromagnetic spectrum. Recent advances in hardware have started to open up the field to new applications such as THz imaging. This non destructive technology can penetrate through diverse material such that the internal structure which is invisible to other imaging modalities, can be visualized. However, automated processing of THz images can be quite challenging. Low contrast and the presence of a widely unknown type of noise make the analysis of these images difficult. Therefore, pre-processing techniques are required for further investigations.