AUTOMATIC OPTIC DISK DETECTION FROM LOW CONTRAST RETINAL IMAGES OF ROP INFANT USING GVF SNAKE
Keywords:
Optic disk, retinopathy of prematurity, segmentation, PCA, Snake, gradient vector flowAbstract
Reliable and efficient optic disk localization and segmentation are important tasks in automated retinal screening. General-purpose edge detection algorithms often fail to segment the optic disk (OD) due to fuzzy boundaries, inconsistent image contrast or missing edge features, especially in infants’ retinal images where the image acquisition process has to be very quick and in low light conditions. This paper presents an algorithm for segmentation of optic disk boundary in low-contrast images. The optic disk localization is achieved using segmentation by a deformable contour model (or Snake) with gradient vector flow (GVF) as an external force. The first Snake is placed at a location very close to the center of the optic disk approximated by a PCA-based model. The algorithm is evaluated using 50 retinal images from infants with retinopathy of prematurity (ROP) condition. The results from the GVF method were compared with conventional optic disk detection using a 2D Circular Hough Transform and later verified with hand-drawn ground truth. The result is quite successful with the accuracy of 85.34%.
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