
基于多图像特征的幼龄沉香全氮估测
袁莹, 王雪峰, 王甜, 陈飞飞, 黄川腾, 林玲, 董晓娜
南京林业大学学报(自然科学版) ›› 2023, Vol. 47 ›› Issue (3) : 19-28.
基于多图像特征的幼龄沉香全氮估测
Estimation of total nitrogen in young Aquilaria sinensis based on multi image features
【目的】应用计算机视觉技术提取幼龄沉香的多图像特征,对沉香叶片全氮含量进行估测,为实现沉香氮营养状态的快速无损估测提供新方法。【方法】采用基于色调-亮度-饱和度(HIS)颜色空间的最佳直方图(KSW)熵法和形态学处理对幼龄沉香图像进行分割,并提取了图像的颜色、形状和纹理特征。然后利用偏最小二乘法(PLS)对多图像特征进行有监督降维,提取图像特征主成分。最后构建了天牛须搜索算法(BAS)优化后的Elman神经网络(Elman neural network,ElmanNN)模型对幼龄沉香叶片全氮量进行估测,并将模型验证结果与其他常用模型进行对比。【结果】以幼龄沉香可见光图像为研究对象,应用的基于HIS空间的分割算法效果优于常用的RGB和Lab颜色空间分割;PLS算法对图像特征提取了6个主成分,快速降低了图像特征的维数,并有效消除了特征变量间的多重共线性;提出的PLS-BAS-ElmanNN模型能实现模型参数的自适应选取,且估测效果较好,决定系数R2为0.740 7,均方根误差(RMSE)为1.265 3 g/kg,估测精度略高于偏最小二乘回归(PLSR)模型和偏最小二乘-广义可加模型(GAM)。【结论】提出以幼龄沉香为研究对象的图像处理方法,构建了能够稳定处理高维图像数据的PLS-BAS-ElmanNN估测模型,为幼龄沉香氮营养状态的监测及沉香培育的精准作业提供了新思路。
【Objective】Multi-image features of young Aquilaria sinensis were extracted using computer vision technology to estimate the total nitrogen content of leaves, providing a new method for rapid and nondestructive measurement of the nitrogen nutritional status of A. sinensis. 【Method】In this study, the best histogram entropy method (KSW entropy method) and morphological processing based on the HIS (Hue-intensity-saturation) color space were used to segment an image of young A. sinensis, and the color, shape and textural features of the image were extracted. Subsequently, the partial least squares (PLS) method was used to reduce the multi-image feature dimensions, and the principal components of the image feature variables were generated. Finally, the Elman neural network (ElmanNN), optimized using the BAS algorithm, was used to estimate the total nitrogen content of young A. sinensis, and the validation results of the model were compared with those of other commonly used models. 【Result】Research showed the following: (1) focusing on the visible image of A. sinensis, the segmentation algorithm based on HIS color space was better than that based on RGB and Lab color space. (2) The PLS algorithm extracted six principal components from the image features, which reduced the dimension of the image features quickly, and effectively eliminated the multicollinearity among the feature variables. (3) The PLS-BAS-ElmanNN model proposed in this study could achieve the adaptive selection of model parameters, and had higher estimation accuracy; for instance, the R2 was 0.740 7 and the root mean square error was only 1.265 3 g/kg. The estimation accuracy of it was slightly higher than that of the PLSR and PLS-GAM models. 【Conclusion】In this study, we proposed an image processing method for young A. sinensis and constructed a PLS-BAS-ElmanNN estimation model that can stably process high-dimensional image data. This provides a new idea for monitoring the nitrogen nutrition status of young A. sinensis and has a very important practical significance for the accurate cultivation of A. sinensis.
沉香 / 全氮 / 计算机视觉 / BAS-Elman / 偏最小二乘法
Aquilaria sinensis / total nitrogen / computer vision / BAS-Elman / PLS
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