Study On Brightness Characteristics Of Colored Objects Under Multi-Chip LED Light Source

Functional lighting is the main type of lighting that people pay attention to.The index system for evaluating the performance of light source,such as light efficiency,color temperature and color rendering,is suitable for general functional lighting.In illumination design aiming at illuminating colored objects,the performance index of light source is relatively inappropriate and needs to be evaluated from the perspective of illuminated objects.The spectrum of traditional light source is relatively fixed,so it is difficult to achieve the optimization of illumination efficiency and effect of the illuminated object.The spectral flexibility of multi-chip LED provides feasibility for optimizing the spectrum of light source and improving the illumination efficiency and effect of illuminated objects.Based on the spectral flexibility of multi-chip LED,this paper focuses on theperceived brightness rule of colored objects irradiated by multi-chip LED light source through theoretical derivation,experimental testing,quantitative analysis,field investigation and other methods.When illuminating an object,the brightness and color effect of the object are determined by both the performance of light source and the reflection characteristics of the object.Traditional photochromic performance indicators are not suitable for the evaluation of the effect of colored objects.Therefore,this paper proposes the concept of perceived brightness of colored objects and evaluates it from the perspective of the object being illuminated.This paper conducts the visual color study around the perceived brightness,focusing on experimental research of two aspects:the influencing factors of the brightness of the color appearance of colored objects and the color fidelity of colored objects.The same illumination level was set in the experiment,the test light source was divided into two groups:high color rendering index group and low color rendering index group,a total of 8 related color temperatures from 2700K to 6500K,and targeted brightness test was performed on 8 color swatches?red,orange,yellow,yellow-green,green,blue-green,blue and purple?.Based on the results of the brightness experiment,the chromatic aberration of the test light source is calculated and its fidelity is compared.Finally,the influence trend of each parameter on illumination effect and the optimal light source selection for different color samples are obtained.The main conclusions are as follows:Firstly,in the experiment of perceived brightness,the most important factor affecting of the brightness is the spectral reflection curve of the color sample,i.e.the spectral reflection characteristics of the object material,when the illumination of the light source is the same.The next is color temperature.The brightness of warm-toned color sample is negatively correlated with the color temperature,while the brightness of cold-toned color sample is positively correlated with the color temperature.When the color temperature is the same,the closer the peak wavelength of the light source is to the main wavelength of the chromaticity corresponding to the color sample,the higher the brightness of the color sample is.Secondly,in the research of fidelity of colored objects,the chromatic aberration of the test light source in the experiment is calculated systematically.It can be divided into two aspects:SDCM value calculation and?E_CIEvalue calculation.The calculated results of chromatic aberration are positively correlated with the brightness value,which is an effective demonstration for optimizing the selection of light sources.The innovations of this paper mainly include two aspects in theory and application.Theoretically:This paper clarifies the importance of the perceived brightness of colored objects,quantitatively predicts and evaluates the effect of illuminating colored objects by light sources and provides some theoretical innovations in the evaluation of the colorimetric characteristics of multi-chip LED.The evaluation parameters are proposed from the irradiated object,which makes the evaluation of the effect of the light source when irradiating the colored object more scientific.The perceived brightness is determined by the light source spectrum,the spectral reflectance of the object and the spectral optical efficiency of the human eye.Therefore,the size of the enclosure area between the function curve and the coordinate axis can predict the brightness of the colored object under the current light source.Applications:This paper investigates the influence factors of light source on the brightness of colored objects,and provides the direction of light source optimization.Considering the brightness,the paper pays attention to the fidelity of the light source,and ensures that it can restore the color of the colored object without"distortion"while having a higher brightness,so that the optimized light source recommended by the experimental results has more application value of marketization.