The objective of this study was to develop a mathematical model for the non-destructive, fast estimation of the leaf chlorophyll (Chl) content of pomegranate trees. For this reason, contact images of the leaf samples were firstly captured with smartphones and the RGB colours of the images were used for the estimation of the leaf Chl contents. Here, different methods were used for the contact imaging. In the present study, two closed boxes with a small hole (equal to the dimensions of a smartphone camera) on each were formed. Samples were inserted into the hole; and a red LED light and white LED light, separately, were passed through the hole and the leaf. Furthermore, a series of models were tested to best estimate the leaf chlorophyll content of the pomegranate trees by using the RGB colours of contact imaging. Results showed that the use of red LED light sources, instead of white LED light sources, during contact imaging, provides a better estimation of the leaf Chl content. Results also suggest that colour values are highly related to the total weight of the contact imaging area. According to the results obtained, the best estimation of the leaf Chl content (of a given area) is possible by using both the G and B colour values with multiple regression models. It is also found to be important to use the weight of the sampled area for the estimation of the leaf chlorophyll content in mg ∙ g⁻¹.

中文翻译：

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基于RGB色彩的智能手机接触式成像估算叶绿素含量的数学模型：一个石榴示例

这项研究的目的是开发一种数学模型，用于无损，快速地估算石榴树的叶绿素（Chl）含量。因此，首先使用智能手机捕获叶片样品的接触图像，并将图像的RGB颜色用于叶片Chl含量的估算。在此，接触成像使用了不同的方法。在本研究中，形成了两个封闭的盒子，每个盒子上都有一个小孔（等于智能手机相机的尺寸）。将样品插入孔中；分别使红色LED灯和白色LED灯穿过孔和叶子。此外，测试了一系列模型，以通过使用接触式成像的RGB颜色来最佳估计石榴树的叶绿素含量。结果表明，在接触成像过程中使用红色LED光源代替白色LED光源可以更好地估算叶片Chl含量。结果还表明，颜色值与接触式成像区域的总重量高度相关。根据获得的结果，可以通过将G和B颜色值与多个回归模型一起使用，对（给定区域的）叶片Chl含量进行最佳估计。还发现使用采样区域的重量来估算以毫克∙克为单位的叶片叶绿素含量也很重要。根据获得的结果，可以通过将G和B颜色值与多个回归模型一起使用，对（给定区域的）叶片Chl含量进行最佳估计。还发现使用采样区域的重量来估算以毫克∙克为单位的叶片叶绿素含量也很重要。根据获得的结果，可以通过将G和B颜色值与多个回归模型一起使用来对（给定区域的）叶片Chl含量进行最佳估计。还发现使用采样区域的重量来估算以毫克∙克为单位的叶片叶绿素含量也很重要。^-1。