IRREGULAR MOTION RECOVERY IN FLUORESCEIN ANGIOGRAMS

Fluorescein angiography is a common procedure in ophthalmic practice, mainly to evaluate vascular retinopathies and choroidopathies from seq uences of ocular fundus images. In order to compare the images, a reli able overlying is essential. This paper proposes some methods for the recovery of irregular motion in fluorescein angiograms (FA). The overl ying is done by a three step procedure: detection of relevant points, matching points from different images and estimation of the assumed li near geometric transformation. A stochastic model (closely related to the general linear model) allows to fuse the second and third steps, T wo different estimators of the geometric transformation are proposed a nd tested with real FAs. Images from choroido-retinal diseases have be en analysed: diabetic retinopathy, vein occlusions and choroidal neova scular membrane. Results have been evaluated using a different number of relevant points with different spatial arrangements. Registration a ccuracy is evaluated as the mean squared error between real and transf ormed relevant point locations for those points not used to estimate t he transformation. (C) 1997 Elsevier Science B.V.