Chromatic Adaptations And Color Qualities Of Lightings

After the widely use of solid state sources,such as light emitting diodes,in daily lightings,the metrics to evaluate the color quality of light sources are in urgent need among the relavant industries and most of the national and international organizations for standardization,due to the high degree of freedom to control solid state source lightings in spectrum,space and time.On the other hand,the existing algorithms of chromatic adaptation transform and the color appearance model need update to involve this new type of light source in the lighting,display,imaging and surface color industries.Two related researches were introduced in the present thesis to meet the above need.The first one was to use a novel psychophysical color matching method to achieve a huge amount of visual data of corresponding colors of chromatic adaptation,with memory colors and neutral whites as intermediaries of stable color appearance.Two independent experiments were conducted in this method,and corresponding colors for wider range of chromaticity of light source than any before were collected.The effect of chromaticity of light source on the degree of adaptation were verified and modeled.The comprehensive two-step chromatic adaptation transform was built and the chromaticity of its baseline illuminant was found.Different from the existing chromatic adaptation transform which can only output into a complete adapted field as reference,the present two-step transform is able to compute between any two incomplete adapted fields.And its degree of adaptation based on the baseline illuminants of different media is clear specified and this reduces prediction error.In vision or color related industries,the two-step transformand the models of adaptation degree could help solve the problems of chromatic adaptation.The other research was to study the parameters affecting generic color quality of lighting which had been divided into two parts,chromaticity with luminance and spectrum characteristic such as color fidelity and color gamut.Method of categorical judgment was use in both lighting experiments in gallery application environment with high color quality requirement,and generic lighting color quality experiments with strictly controlled and independent parameter settings.Impact of each parameter or metric,such as color temperature,chromaticity,luminance,illumiance,color fidelity,color gamut size,color gamut shape,chroma shift was analyzed.The ways to evaluate the perception of visual comfort,colorfulness and preference were discussed.The chroma shift of red hue bin was proved to be effective in prediction of visual colorfulness and the most preferred gain of red hue bin chroma is fifteen percent of reference source.The model of preference was built with relatively good performance.These results and models in the present thesis helped the industries develop their own high-performance algorithm,and opened up a new field of research in vision and color science.