Raw Quality Value Classification of Ethiopian Coffee Using Image Processing Techniques: In the Case of Wollega Region

Baleker, Asma Redi (2011) Raw Quality Value Classification of Ethiopian Coffee Using Image Processing Techniques: In the Case of Wollega Region. Masters thesis, Addis Ababa University.

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Abstract

Development of an automated computer vision system aiming in the establishment of technological and innovative approaches towards sample coffee bean raw quality value classification by extracting the relevant coffee bean features is the focal issue of this exploratory research. Of paramount significance in this regard is addressing the identified problems of the tedious and inefficient manual grading and sorting mechanisms of one of the most important agricultural products in Ethiopia, coffee. Prevalent sorting and classification approaches are characterized by subjective assessments of the features and nature of this huge economy representing crop, thereby influencing quality control and productivity aspects of the product. The major objective of the research spans extraction and selection of the important coffee bean morphological and color features that are useful for the purpose of classification of the raw quality grade level of sample coffee beans by designing, analyzing and testing a digital image processing model. The automated raw quality value classification experimentation comprised the analysis of images of washed coffee beans of varying grades from Wollega region, using major attributes of morphological structures (shape and size), and color features. Grades 2 – 9 of the coffee beans were available, providing a total of 27 samples, which yielded 324 sample images after a series of re-sampling measures of same into 12 sub-samples. The overall image processing work to develop models and depict trends for an efficient raw quality value classification involved sequential phases of image acquisition, image enhancement and segmentation, feature extraction, attribute selection, classification and performance evaluation. The Naïve Bayes, C4.5 and Artificial neural networks (ANN) were implemented for such classification purposes. A combined morphological and color features aggregate function dataset was used to develop the base model, though model attempts with separate features were conducted. Feed-forward multilayer perceptrons with two hidden layer and backpropagation algorithms are used in the ANN classifiers. Discretization of the raw quality value in to three interval classes was done to improve the performance of the model. 75% split evaluation technique was implemented for the Naïve Bayes and ANN classifiers as 10-foldcross validation evaluation techniques implemented in C4.5. Naïve Bayes classifier yielded higher model performance (82.72% correctly classified), followed by C4.5 (82.09%) and the ANN classifier (80.25%). Model robustness and sensitivity was analyzed by using perturbation analysis involving manipulations of model evaluation techniques and dataset characters. Alteration of number of beans in discretization and the use of different number of hidden layers constitute the trial modeling in this regard. Classification model was also run with various combinations of features of the coffee beans as listed with the attribute selection feature of Weka tool, where the final selection of the 21 features was done at a maximal model performance level for the Naïve Bayes and ANN classification approachs. C4.5 selected 10 features as it has its own attribute selection characteristics. An additional simulation was done with regression analysis for the sake of evaluation and trends analysis of the model outputs. A higher relation was resulted from this statistical approach between the raw quality values and the mentioned coffee bean features, supporting suitability and accuracy of dataset for classification in this research.

Item Type:	Thesis (Masters)
Subjects:	Q Science > QA Mathematics > QA75 Electronic computers. Computer science Q Science > QH Natural history > QH301 Biology Q Science > QK Botany
Divisions:	Africana
Depositing User:	Selom Ghislain
Date Deposited:	22 Aug 2018 06:31
Last Modified:	22 Aug 2018 06:33
URI:	http://thesisbank.jhia.ac.ke/id/eprint/4901

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