Research On Color Measurement System Based On Hyperspectral Imaging Technology

Color is an important parameter in the quality control of industrial production.Color evaluation by visual method is inefficient,and the evaluation results are easily affected by environmental and personal subjective factors.In the prior art,the spectrophotometer is with good repeatability and high accuracy,but the spatial resolution is low.In practical application,it can only measure the pure color and can not measure the complex color patterns.Color camera has high spatial resolution,but its spectral resolution is low,so it is not suitable for accurate color measurement and color communication.This paper designs a color measurement system based on hyperspectral imaging technology.The system can obtain the image information of the object surface in the area of 25 mm x 25 mm,with a spatial resolution of 44.19 μm,and spectral reflectance and chromaticity information of each pixel can be viewed in the wavelength range 400-700 nm.The research work of this paper can be divided into 3 parts:1.Build a complete optical path structure of hyperspectral color measurement instrument.An optical path structure based on D/8 illumination observation conditions is designed,and the data is collected by line scanning hyperspectral camera;The stepping motor is used as the translation and sweeping device to expand the one-dimensional information collected by the hyperspectral camera into two-dimensional spatial position information.2.The spectral calibration algorithm,dual optical path sampling algorithm and energy calibration algorithm of hyperspectral color measurement instrument are studied.Mercury argon lamp is used to calibrate the relationship between the wavelength and pixels of hyperspectral camera.Through the response value of adjacent pixels under a single wavelength,the precise position of the wavelength peak is determined to improve the accuracy of wavelength calibration;The hyperspectral camera collects the reflection spectrum information of the light source and the sample at the same time,and monitor the fluctuation of the light source to improve the repeatability of measurement;The spectral reflectance calibration of each spatial channel of hyperspectral camera is realized by using the spectral response value data of standard gray plate.3.The optimization algorithm of hyperspectral image quality is constructed.Confirm the spectral signal offset of all spatial channels through the wavelength calibration of limited spatial channels,and correct the inconsistency of chromaticity measurement results at different spatial positions caused by smile;By collecting the images of black-and-white grid test card,the spatial matching error caused by keystone effect is observed intuitively,and the offset generated in different spectral channels is determined.The influence caused by keystone is corrected by shift output algorithm.The whole machine evaluates the color measurement performance of the system according to the national metrological verification regulation JJG595-2002,reaching the level of first-class metrological qualification.