Study Of Multi-spectral Imaging System Based On Spectral Tunable LED Light Source

Focus on the problem of traditional multi spectral imaging system include the follow shortcoming: complex calculation and a large amount of calculation in the spectral reflectance reconstruction and high cost etc.A new method was proposesed to construct multi spectral imaging system in this paper.The LED active illumination and monochrome high-speed camera were used to construction of multi spectral imaging system of visible spectral region.The method used is mainly based on the spectral sensitivity curve of black and white camera and based on the reciprocal of this spectral sensitivity curve to fitting the spectral power distribution of the LED active illuminator.The specific implementation process is as follow: Firstly,measuring the spectral sensitivity curve of black and white camera.Then,use the LED light to fitting lighting source that the spectral power distribution is the reciprocal of the spectral sensitivity curves of the black and white camera.Finally,build the multi spectral imaging system.Firstly we need to measure the spectral sensitivity curves of black and white camera in the course of the study.Two methods were proposed to measuring the camera spectral sensitivity curve in this paper,monochromator measurement method and digital image measurement method.The first method by capturing the images of the standard whiteboard under the conditions of different monochromatic light illumination and measuring the spectral power distribution of different monochromatic light distribution,so we can get the spectral sensitivity curve of the camera.The second method by capturing the image of standard color chart under the conditions of natural light illumination and measuring spectral power distribution of the natural light source,Finally,we can obtain the spectral sensitivity curve by calculate.By comparison,the two methods can both measure the spectral sensitivity of the camera accurately.Based on the reciprocal of the spectral sensitivity curve of black and white camera to fitting the spectral power distribution of the LED active illuminator.After get the spectral power distribution of each LED light source,by using the least squares optimization method to fit the needs of the light source.Build a multi spectral imaging system and capturing the multi spectral images of standard color chart.Finally,preliminary explore to reconstruct of the spectral reflectance of each color block in the standard color chart from the camera response.