Machine Learning Methods for Automatic Segmentation of Images of Field- and Glasshouse-Based Plants for High-Throughput Phenotyping

Image segmentation is a fundamental but critical step for achieving automated high- throughput phenotyping. While conventional segmentation methods perform well in homogenous environments, the performance decreases when used in more complex environments. This study aimed to develop a fast and robust...

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Main Authors: Frank Gyan Okyere, Daniel Cudjoe, Pouria Sadeghi-Tehran, Nicolas Virlet, Andrew B. Riche, March Castle, Latifa Greche, Fady Mohareb, Daniel Simms, Manal Mhada, Malcolm John Hawkesford
Format: Article
Language:English
Published: MDPI AG 2023-05-01
Series:Plants
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Online Access:https://www.mdpi.com/2223-7747/12/10/2035
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author Frank Gyan Okyere
Daniel Cudjoe
Pouria Sadeghi-Tehran
Nicolas Virlet
Andrew B. Riche
March Castle
Latifa Greche
Fady Mohareb
Daniel Simms
Manal Mhada
Malcolm John Hawkesford
author_facet Frank Gyan Okyere
Daniel Cudjoe
Pouria Sadeghi-Tehran
Nicolas Virlet
Andrew B. Riche
March Castle
Latifa Greche
Fady Mohareb
Daniel Simms
Manal Mhada
Malcolm John Hawkesford
author_sort Frank Gyan Okyere
collection DOAJ
description Image segmentation is a fundamental but critical step for achieving automated high- throughput phenotyping. While conventional segmentation methods perform well in homogenous environments, the performance decreases when used in more complex environments. This study aimed to develop a fast and robust neural-network-based segmentation tool to phenotype plants in both field and glasshouse environments in a high-throughput manner. Digital images of cowpea (from glasshouse) and wheat (from field) with different nutrient supplies across their full growth cycle were acquired. Image patches from 20 randomly selected images from the acquired dataset were transformed from their original RGB format to multiple color spaces. The pixels in the patches were annotated as foreground and background with a pixel having a feature vector of 24 color properties. A feature selection technique was applied to choose the sensitive features, which were used to train a multilayer perceptron network (MLP) and two other traditional machine learning models: support vector machines (SVMs) and random forest (RF). The performance of these models, together with two standard color-index segmentation techniques (excess green (ExG) and excess green–red (ExGR)), was compared. The proposed method outperformed the other methods in producing quality segmented images with over 98%-pixel classification accuracy. Regression models developed from the different segmentation methods to predict Soil Plant Analysis Development (SPAD) values of cowpea and wheat showed that images from the proposed MLP method produced models with high predictive power and accuracy comparably. This method will be an essential tool for the development of a data analysis pipeline for high-throughput plant phenotyping. The proposed technique is capable of learning from different environmental conditions, with a high level of robustness.
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spelling doaj.art-8978905b5f7f4babbf4cae606176a4082023-11-18T02:56:42ZengMDPI AGPlants2223-77472023-05-011210203510.3390/plants12102035Machine Learning Methods for Automatic Segmentation of Images of Field- and Glasshouse-Based Plants for High-Throughput PhenotypingFrank Gyan Okyere0Daniel Cudjoe1Pouria Sadeghi-Tehran2Nicolas Virlet3Andrew B. Riche4March Castle5Latifa Greche6Fady Mohareb7Daniel Simms8Manal Mhada9Malcolm John Hawkesford10Sustainable Soils and Crops, Rothamsted Research, Harpenden AL5 2JQ, UKSustainable Soils and Crops, Rothamsted Research, Harpenden AL5 2JQ, UKSustainable Soils and Crops, Rothamsted Research, Harpenden AL5 2JQ, UKSustainable Soils and Crops, Rothamsted Research, Harpenden AL5 2JQ, UKSustainable Soils and Crops, Rothamsted Research, Harpenden AL5 2JQ, UKSustainable Soils and Crops, Rothamsted Research, Harpenden AL5 2JQ, UKSustainable Soils and Crops, Rothamsted Research, Harpenden AL5 2JQ, UKSchool of Water, Energy and Environment, Soil, Agrifood and Biosciences, Cranfield University, Bedford MK43 0AL, UKSchool of Water, Energy and Environment, Soil, Agrifood and Biosciences, Cranfield University, Bedford MK43 0AL, UKAfrican Integrated Plant and Soil Science, Agro-Biosciences, University of Mohammed VI Polytechnic, Lot 660, Ben Guerir 43150, MoroccoSustainable Soils and Crops, Rothamsted Research, Harpenden AL5 2JQ, UKImage segmentation is a fundamental but critical step for achieving automated high- throughput phenotyping. While conventional segmentation methods perform well in homogenous environments, the performance decreases when used in more complex environments. This study aimed to develop a fast and robust neural-network-based segmentation tool to phenotype plants in both field and glasshouse environments in a high-throughput manner. Digital images of cowpea (from glasshouse) and wheat (from field) with different nutrient supplies across their full growth cycle were acquired. Image patches from 20 randomly selected images from the acquired dataset were transformed from their original RGB format to multiple color spaces. The pixels in the patches were annotated as foreground and background with a pixel having a feature vector of 24 color properties. A feature selection technique was applied to choose the sensitive features, which were used to train a multilayer perceptron network (MLP) and two other traditional machine learning models: support vector machines (SVMs) and random forest (RF). The performance of these models, together with two standard color-index segmentation techniques (excess green (ExG) and excess green–red (ExGR)), was compared. The proposed method outperformed the other methods in producing quality segmented images with over 98%-pixel classification accuracy. Regression models developed from the different segmentation methods to predict Soil Plant Analysis Development (SPAD) values of cowpea and wheat showed that images from the proposed MLP method produced models with high predictive power and accuracy comparably. This method will be an essential tool for the development of a data analysis pipeline for high-throughput plant phenotyping. The proposed technique is capable of learning from different environmental conditions, with a high level of robustness.https://www.mdpi.com/2223-7747/12/10/2035feature extractionimagingmachine learningphenotypingsegmentation
spellingShingle Frank Gyan Okyere
Daniel Cudjoe
Pouria Sadeghi-Tehran
Nicolas Virlet
Andrew B. Riche
March Castle
Latifa Greche
Fady Mohareb
Daniel Simms
Manal Mhada
Malcolm John Hawkesford
Machine Learning Methods for Automatic Segmentation of Images of Field- and Glasshouse-Based Plants for High-Throughput Phenotyping
Plants
feature extraction
imaging
machine learning
phenotyping
segmentation
title Machine Learning Methods for Automatic Segmentation of Images of Field- and Glasshouse-Based Plants for High-Throughput Phenotyping
title_full Machine Learning Methods for Automatic Segmentation of Images of Field- and Glasshouse-Based Plants for High-Throughput Phenotyping
title_fullStr Machine Learning Methods for Automatic Segmentation of Images of Field- and Glasshouse-Based Plants for High-Throughput Phenotyping
title_full_unstemmed Machine Learning Methods for Automatic Segmentation of Images of Field- and Glasshouse-Based Plants for High-Throughput Phenotyping
title_short Machine Learning Methods for Automatic Segmentation of Images of Field- and Glasshouse-Based Plants for High-Throughput Phenotyping
title_sort machine learning methods for automatic segmentation of images of field and glasshouse based plants for high throughput phenotyping
topic feature extraction
imaging
machine learning
phenotyping
segmentation
url https://www.mdpi.com/2223-7747/12/10/2035
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