Evaluation Of Colour Appearance In A Real Lit Room

LED is now widely used in indoor and outdoor lightings. Comparing with traditional lights, including tungsten and fluorescent lights, LED lights have the advantage of longer life and low energy consumption. In addition, LED lights are more adaptive. Their parameters such as colour temperature and illuminance could be adjusted to satisfy consumers’ needs. White lighting are mainly used in daily life. It could be divided into cool white and warm white. Rea and Fressinier from Lighting Research Center in Rensselaer Polytechnic Institute found a locus to represent white lighting. The whites are located above the blackbody locus when CCT> 4000K and below the locus when CCT<4000K. However, in their experiment, observers made estimations in a viewing box, which may not provide full adaption. Hence, the first part of our research is to investigate white lighting in a real room and establish a locus to represent white lighting. The new locus verified Rea and Fressinier’s conclusion In the second part, observers also estimated the appearance of the room and colour patches, including brightness, colourfulness, warmth, whiteness and hue composition. And then the relationships between different appearance attributes were analyzed. The results showed that hue composition has effects on other attributes, i.e. when the room was illuminated by lights with purple/pinkish tint, it looks brighter, whiter, cooler and less colourful. Brightness also affects room appearance, i.e. a brighter room looks cooler, whiter, less colourful. When colour patches become brighter, the colourfulness also increases, which verifies Hunt effect. However, the colourfulness of the room decreases when it becomes brighter. It is because that the room was mainly constituted by white walls. At last, the effects of CCT and Duv on room appearance including brightness, colourfulness and hue compositions were investigagted. As CCT increases, the room and colour patches become brighter. And the colourfulness of the room decreases first and then increases as CCT increases. CCT has little effect on the colourfulness of colour patches. As Duv increases from negative to positive, the room and colour patches become less bright and the colour patches become less colourful. Duv has little effect on the colourfulness of the room. As CCT increases, the hue composition increases while Duv has little effect on hue composition.