Image mosaicing of low quality neonatal retinal images

Retinopathy of prematurity (ROP) is a vascular disease in premature infants. This is characterized by abnormal vessel growth and subsequent fibrosis in the peripheral retina. The prognosis of ROP relies on information on the presence of abnormal growth and their location. Diagnosis is based on a series of images obtained with a wide field of view camera (such as RetCam), to capture the complete retina. In this paper, we present a novel and efficient hierarchal mosaicing algorithm, for neonatal images of varying quality. We employ a vessel-based quality metric and exploit the knowledge of the retinal structure to automatically select a subset of images from a given set, to construct a good quality mosaic. Such mosaics can aid the assessment of ROP by providing a comprehensive and complete view of the entire retina. The hierarchal approach underlying the method makes it possible to complete the mosaicing task in close to real time. The proposed method has been tested on 14 sets of data with each set consisting of 6-35 retinal images acquired using RetCam and the generated mosaics are found to be of good quality as validated by a clinical expert.