In this thesis, the systematic assessment of blackness has been studied by analyzing the spectral and colorimetric behaviors of blacks. In this way, 624 black samples with various lightness, chroma and hue angles were prepared by printing the papers as well as dyeing and printing the fabrics. Hence, the essential dataset for spectral and colorimetric analysis of blacks was prepared by measuring the reflectance spectra of them and computing their colorimetric attributes under desired conditions. In order to investigate the spectral behavior of blacks, three black dataset including black papers, fabrics and a third containing all samples were introduced in three spectral domains comprising reflectance, absorbance and reversed reflectance spaces. To determine the spectral dimensions of blacks, the mentioned datasets were compressed in identified domains by employing the principal component analysis technique (PCA). The proposed datasets were reconstructed spectrally and colorimetrically and the corresponding dimensions were identified according to the lost data. Results of spectral reconstruction of blacks indicated to the sufficiency of 2 or 3 statistic primaries for describing blacks in mentioned domains. As expected, the colorimetric reconstruction of reflectance spectra of blacks resulted in metamer pairs with small metamerism indices, i.e. acceptable spectral and colorimetric errors. In addition to PCA technique and in order to find more feasible primaries, the non-negative matrix factorization method (NNMF) was employed to extract the non-negative vectors of blacks in reflectance space. Results of spectral reconstruction of blacks by employing 1 to 3 non-negative vectors indicated to preference of applying of 3 primaries in comparison to 1 or 2 vectors. The comparing of PCA and NNMF methods showed that there is not a critical difference between them for recovering the blacks. Meanwhile, in contrary to color samples, there are not three unique colors with specific dominant wavelengths to describe blacks. This could refer to the probability of creation of blacks with several primaries. In order to investigate the effects of colorimetric attributes on blackness perception, 216 black fabrics with various colorimetric properties were visually evaluated. Both pair comparison and rank ordering methods were employed for visual evaluation of samples and the results showed the simultaneous effect of lightness, chroma and hue on blackness perception however, the greenish-bluish blacks were evaluated in higher degree of blackness. Moreover, investigation of repeatability and reproducibility of visual experiments by considering the wrong decision criteria showed that the observers assessed blackness, precisely. Finally, evaluation of presented blackness indices showed the higher performance of Westland blackness index in assessment of black samples which have been evaluated in this study via pair comparison method. Keywords: Blackness, Principal component analysis, Non-negative matrix factorization, Visual assessment, Repeatability and reproducibility.