title: Diagnosis of retinal health in digital fundus images using continuous wavelet transform (CWT) and entropies.
abstract: Vision is paramount to humans to lead an active personal and professional life. The prevalence of ocular diseases is rising, and diseases such as glaucoma, Diabetic Retinopathy (DR) and Age-related Macular Degeneration (AMD) are the leading causes of blindness in developed countries. Identifying these diseases in mass screening programmes is time-consuming, labor-intensive and the diagnosis can be subjective. The use of an automated computer aided diagnosis system will reduce the time taken for analysis and will also reduce the inter-observer subjective variabilities in image interpretation. In this work, we propose one such system for the automatic classification of normal from abnormal (DR, AMD, glaucoma) images. We had a total of 404 normal and 1082 abnormal fundus images in our database. As the first step, 2D-Continuous Wavelet Transform (CWT) decomposition on the fundus images of two classes was performed. Subsequently, energy features and various entropies namely Yager, Renyi, Kapoor, Shannon, and Fuzzy were extracted from the decomposed images. Then, adaptive synthetic sampling approach was applied to balance the normal and abnormal datasets. Next, the extracted features were ranked according to the significances using Particle Swarm Optimization (PSO). Thereupon, the ranked and selected features were used to train the random forest classifier using stratified 10-fold cross validation. Overall, the proposed system presented a performance rate of 92.48%, and a sensitivity and specificity of 89.37% and 95.58% respectively using 15 features. This novel system shows promise in detecting abnormal fundus images, and hence, could be a valuable adjunct eye health screening tool that could be employed in polyclinics, and thereby reduce the workload of specialists at hospitals.
authors.affiliation: Department of Electronics and Computer Engineering, Ngee Ann Polytechnic, 599489 Singapore, Singapore.
authors.forename: Joel E W
authors.initials: JEW
authors.lastname: Koh
authors.affiliation: Department of Electronics and Computer Engineering, Ngee Ann Polytechnic, 599489 Singapore, Singapore; Department of Biomedical Engineering, School of Science and Technology, SIM University, 599491 Singapore, Singapore; Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Malaysia, Malaysia. Electronic address: aru@np.edu.sg.
authors.forename: U Rajendra
authors.initials: UR
authors.lastname: Acharya
authors.affiliation: Department of Electronics and Computer Engineering, Ngee Ann Polytechnic, 599489 Singapore, Singapore.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hagiwara
authors.affiliation: Department of Instrumentation and Control Engineering, Manipal Institute of Technology, Manipal University, Manipal 576104, India.
authors.forename: U
authors.initials: U
authors.lastname: Raghavendra
authors.affiliation: Department of Electronics and Computer Engineering, Ngee Ann Polytechnic, 599489 Singapore, Singapore.
authors.forename: Jen Hong
authors.initials: JH
authors.lastname: Tan
authors.affiliation: Visiting Scientist, Global Biomedical Technologies, CA, USA.
authors.forename: S Vinitha
authors.initials: SV
authors.lastname: Sree
authors.affiliation: Department of Ophthalmology, Kasturba Medical College, Manipal 576104, India.
authors.forename: Sulatha V
authors.initials: SV
authors.lastname: Bhandary
authors.affiliation: Department of Ophthalmology, Kasturba Medical College, Manipal 576104, India.
authors.forename: A Krishna
authors.initials: AK
authors.lastname: Rao
authors.affiliation: Consultant ophthalmologist, NIHR Moorfields Biomedical Research Centre, London, United Kingdom.
authors.forename: Sobha
authors.initials: S
authors.lastname: Sivaprasad
authors.affiliation: Department of Electronics and Computer Engineering, Ngee Ann Polytechnic, 599489 Singapore, Singapore.
authors.forename: Kuang Chua
authors.initials: KC
authors.lastname: Chua
authors.affiliation: National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore 308433, Singapore.
authors.forename: Augustinus
authors.initials: A
authors.lastname: Laude
authors.affiliation: Singapore Eye Research Institute, Ocular Surface Research Group, Singapore, Singapore; Singapore National Eye Center, Cornea and External Eye Disease Department, Singapore, Singapore; Duke-National University of Singapore Graduate Medical School, Singapore, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Louis
authors.initials: L
authors.lastname: Tong
mesh_terms: D016208:Databases, Factual; D003941:Diagnostic Techniques, Ophthalmological; D019277:Entropy; D005654:Fundus Oculi; D005901:Glaucoma / Q000000981:diagnostic imaging; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D012160:Retina / Q000000981:diagnostic imaging*; D012164:Retinal Diseases / Q000000981:diagnostic imaging*; D058067:Wavelet Analysis
keywords: Age-related macular degeneration; Continuous wavelet transform; Diabetic retinopathy; Fundus; Glaucoma