| Abstract [eng] |
The goal of this master's thesis is to investigate a possibility to use lighting device with multiple individually controlled channels to restore deteriorated colors of a surface. In simulated lighting experiments spectra values of lighting device with 10 channels created by Vilnius university lighting group researchers and measured characteristics of 25 color samples that were artificially aged by the same group were used. The problem of color restoration was reduced into a minimization problem, which searches for intensities of individual lighting channels that minimize restoration error of color samples. Nelder-Mead algorithm was used to solve the optimization problem. In minimization problem four criteria that measured color difference of individual color sample were used. Virtual restoration experiments were done for combinations of one, two, three, four, five and all color samples. After these experiments were carried out, a conclusion was drawn that it is possible to fully restore only a couple of colors using a single lighting. Full restoration of many colors is practically not achievable: restoration of one color may negatively affect other colors that are being restored. This can be explained by small number of initial light channels (number of controlled variables) and wide spectrum of these light sources (no less than 30nm LED spectrum). |
