IMPROVEMENT OF THE CIE COLOUR RENDERING EVALUATION METHOD TO CONFORM TO WHITE LEDS

Visual perceiving experiment on colour rendering of two types of white LEDs, dichromatic and trichromatic, comparing with three types of conventional fluorescent lamps of the same correlated colour temperature has been proceeded. Experimental booths of 486 mm x 474 mm x 620 mm with internal black coating are used. Visual perceiving properties of same colour objects illuminated under test sources, comparing with illuminated under reference source, were evaluated by seven point scale. As objects perceived, 15 sheets of colour chart according to spectral reflectance distribution specified by the CIE 13.3 as test colour for calculation of Colour Rendering Indices were applied. A coefficient of correlation between an average of actual visual perceiving scores for 8 test colour sheets and the value of CIE General Colour Rendering Index (Ra) was compared. And colour gamut area for this 8 test colours was examined. It can be concluded that the CIE colour rendering specifying method might be roughly applicable to evaluate colour rendering properties of white LEDs however, at the same time it can be suggested that any sort of additional and interpolating method seems to be necessary for further evaluation of colour rendering properties of white LEDs.