高光谱成像技术无损检测赣南脐橙表面农药残留研究

Study on Nondestructive Detecting Gannan Navel Pesticide Residue with Hyperspectral Imaging Technology

高光谱成像技术具备图像和光谱的双重优势,作为一种快速无损检测分析技术,检测过程无损、无污染和无接触。高光谱成像数据包括样本的图像信息和光谱信息,采集样本高光谱成像数据时,样本的每个像素点都有一条光谱与之对应,样本的每个波长都有一幅灰度图像与之对应。研究采用高光谱成像技术无损检测不同稀释浓度的农药在赣南脐橙样品表面残留随时间变化的关系。用蒸馏水把农药分别配置成1∶20,1∶100和1∶1 000倍的溶液。然后把不同浓度的溶液滴到30个洗净的脐橙表面,将涂有农药的脐橙分别放置0,4和20d,然后采集在900~1 700nm波长范围的高光谱成像原始数据。通过主成分分析获取930,980,1 100,1 210,1 300,1 400,1 620和1 680nm共8个特征波长,基于这些特征波长做第二次主成分分析,应用PC-2图像并经过适当的图像处理方法对不同浓度及放置不同天数的农药残留进行无损检测。采用高光谱成像技术检测三个时间段较高稀释浓度的果面农药残留都比较明显。高光谱成像技术作为一种检测方法,可用于评价各个时间段较高浓度的农药残留。

Hyperspectral imaging technology is a rapid,non-destructive,and non-contact technique which integrates spectroscopy and digital imaging to simultaneously obtain spectral and spatial information.Hyperspectral images are made up of hundreds of contiguous wavebands for each spatial position of a sample studied and each pixel in an image contains the spectrum for that specific position.With hyperspectral imaging,a spectrum for each pixel can be obtained and a gray scale image for each narrow band can be acquired,enabling this system to reflect componential and constructional characteristics of an object and their spatial distributions.In this study,hyperspectral image technology is used to discuss the application of hyperspectral imaging detection technology of Jiangxi navel orange surface of different concentrations of pesticide residue changes with time relationship.The pesticide was diluted to 1∶20,1∶100and 1∶1 000 solution with distilled water.A 1×2matrix of dilutions was applied to each of 30 cleaned samples with different density pesticide residue.After 0,4and 20 drespectively,hyperspectral images in the wavelength range from 900 to 1 700 nm are taken.The characteristic wavelengths are achieved by using principal component analysis（PCA）and the PC-2image based on PCA using characteristic wavelengths（930,980,1 100,1 210,1 300,1 400,1 620 and 1 680nm）as the classification and recognition of image.Based on these 8characteristic wavelengths for a second principal component analysis,the application of PC-2image and appropriate image processing methods for different concentrations and different days of placing pesticide residues in non-destructive testing were applied.Using hyperspectral imaging technology to detect three periods a higher dilution of the fruit surface pesticide residues are more obvious.This research shows that the technology of hyperspectral imaging can be used to effectively detect pesticide residue on Gannan navel surface.