| The rapid development of science and technology brings a new phase of revolution to the lighting industry that LED sources are gradually replacing conventional sources in various applications.Hence,the lighting quality of LED sources are being of greater importance.According to the two essential measures recommended by ISO,two psychophysical experiments focused on colour rendering index(CRI)and metamerism index(MI)respectively were conducted to evaluate the lighting quality of LED sources.The CRI experiment adopted the grey scale method to obtain the visual colour differences of thirty samples under nine pairs of light sources(reference and test source)given by ten observers.The results indicated that CAM02-UCS showed the best performance among all the four uniform colour spaces,which gave the highest correlation coefficient with perceived colour differences.It was also found that all the colour fidelity metrics gave similar good performance,performed slightly better than the colour preference metrics and markedly outperformed the colour gamut metrics.A large scale of colour difference dataset was accumulated,and effective advices were given to quantify the lighting quality of LED sources accurately.Furthermore,these results made contributions to CIE TC1-90 about the development and improvement of the new colour rendering metric.The MI experiment investigated the perceived quality of LED based simulators from the aspects of colour difference and colour appearance,and compared the performance of LED simulators with conventional simulators.The experiment applied CIE standard illuminant as reference and using thirty metameric pairs as samples.It was found that LED outperformed flourenscent in simulating CIE illuminant D50 by a large margin,and worked almost equally well as tungsten for CIE illuminant A condition.These findings strongly indicated the good quality of LED simulators based on a limited number of channels,and the superiority of LED technology. |
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