Ординатура / Офтальмология / Английские материалы / Automated Image Detection of Retinal Pathology_Jelinek, Cree_2009
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Automated Image Detection of Retinal Pathology |
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8
Segmentation of Retinal Vasculature Using
Wavelets and Supervised Classification:
Theory and Implementation
Joao˜ V. B. Soares and Roberto M. Cesar Jr.
CONTENTS
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
8.2 Theoretical Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
8.3 Segmentation Using the 2-D Gabor Wavelet and Supervised Classification . 235
8.4 Implementation and Graphical User Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
8.5 Experimental Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
8.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
8.1Introduction
Inspection of the optic fundus vasculature can reveal signs of hypertension, diabetes, arteriosclerosis, cardiovascular disease, and stroke [1]. Retinal vessel segmentation is a primary step towards automated analysis of the retina for detection of anomalies and image registration. Automated assessment of the retinal vasculature morphology can be used as part of a screening tool for early detection of diabetic retinopathy, while retinal image registration is of interest in detecting retinal changes, mosaic synthesis, and real-time tracking and spatial referencing for assistance in laser surgeries.
Different techniques are used for acquiring retinal images. Most common are colored or monochromatic photography and angiography using fluorescent dyes. In monochromatic photography, color filters are used to select light wavelengths that enhance the visibility of various fundus structures. Lighting using wavelengths close to the green region of the spectrum (known as red-free lighting) is frequently employed, as it leaves vessels, hemorrhages, and exudates more apparent. Angiographies, on the other hand, require the injection of a small amount of fluorescent dye
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