Blind restoration of fluorescein angiography images

Abstract

In this paper, a new technique is presented to enhance the blurred images obtained from Fluorescein Angiography (FA) of the retina. One of the main steps in inspecting the eye (especially the deeper image of retina) is to look into the eye using a slit-lamp apparatus that shines a monochromatic light on to the retinal surface and captures the reflection in the camera as the retinal image. When further probing is required, such imaging is preceded by injecting a specialized dye in the eye blood vessels. This dye shines out more prominently in the imaging system and reveals the temporal as well as special behavior of the blood vessels, which, in turn, is useful in the diagnosis process. While most of the cases, the image produced is quite clean and easily used by the ophthalmologists, there are still many cases in which these images come out to be very blurred due to the disease in the eye such as cataract etc... in such cases, having an enhanced image can enable the doctors to start the appropriate treatment for the underlying disease. The proposed technique utilizes the Blind Deconvolution approach using Maximum Likelihood Estimation approach. Further post-processing steps have been proposed as well to locate the Macula in the image which is the zero-center of the image formed on the retina. The post-processing steps include thresholding, Region Growing, and morphological operations.