Enhanced color visualization by spectral imaging: An application in cultural heritage

Color is an effective communication media in the objects of Art and historical (A&H) significance. However, as age increases, the objects become prone to color change through weather conditions, handling, display or preservation tasks. Therefore, to monitor the overall color change or to detect discolored area, it is important to precisely visualize the colored surface. This paper shows that RGB values computed using surface reflectance in (400-1000) nm wavelength range are capable to automatcially highlight any subtle color defect. Classical carpets are chosen to exemplify the outputs in this study. The extended CIE color matching functions based visualization method is most effective to render each multivariate data point by a single color. The defective areas of the surface in the resulting images appear strong to be detected readily. However, the conventional RGB colors fail mostly to reveal these color defects. Since spectral imaging is non-destructive and wide-area resolved, presented technique offers a comprehensive understanding of the color conditions of the A&H objects. So the visualization method should help the conservators to make informative decisions about different conservation and restoration strategies.