Automated detection of red lesions from digital colour fundus photographs

Abstract

Earliest signs of diabetic retinopathy, the major cause of vision loss, are damage to the blood vessels and the formation of lesions in the retina. Early detection of diabetic retinopathy is essential for the prevention of blindness. In this paper we present a computer-aided system to automatically identify red lesions from retinal fundus photographs. After pre-processing, a morphological technique was used to segment red lesion candidates from the background and other retinal structures. Then a rule-based classifier was used to discriminate actual red lesions from artifacts. A novel method for blood vessel detection is also proposed to refine the detection of red lesions. For a standarised test set of 219 images, the proposed method can detect red lesions with a sensitivity of 89.7% and a specificity of 98.6% (at lesion level). The performance of the proposed method shows considerable promise for detection of red lesions as well as other types of lesions.

Detection of hemorrhages for diagnosis of malarial retinopathy

“…Grayscale image is obtained by extracting the green channel of RGB color space as it has better contrast then other two channels [21]. Background mask is estimated by first applying adaptive threshold on grayscale image (green channel) and then small false objects are removed using morphological operation (opening and closing).…”

Automatic Detection of Microaneurysms and Hemorrhages in Color Eye Fundus Images

“…Kande et al [16] use operators of mathematical morphology to extract candidate regions, proposing a classifier based on Support Vector Machines (SVM). Jaafar et al [5], Niemeijer et al [9] and Ravishankar et al [17] also used techniques of mathematical morphology for detection of red lesions, getting satisfactory results.…”

“…Later, it was extracted the green channel of the RGB color space, which has better contrast when compared to the other channels [5]. The grayscale image f1 of each fundus image f was obtained according to Eq.…”

“…The earliest signs of DR are characterized by the appearance of red lesions on the wall of the blood vessels of the retina [5], and these red lesions are classified in two ways: microaneurysms and hemorrhages.…”

“…Fundus photography is a noninvasive technique for photographing the fundus eye and is commonly used in current methods for detection of microaneurysms and hemorrhages, such as [2,4,5,9]. Fluorescein angiography is an invasive technique based on intravenous injection of a fluorescent substance, which produces images with enhanced contrast.…”