Retinal Image Registration for Blood Flow Transit Time Estimation

In the past years, much research has been done about ocular hemodynamics using fluorescein angiography. One of the most promising parameters is the transit time of retinal blood flow, which tries to determining how long a dye takes in reach, fills out and leaves the human retina. To achieve this, both individual angiograms and sets of them have to be analyzed. In order to perform this analysis in an automatic fashion, retinal images must be aligned due to the retinal features do not line up, completely, in each frame of the angiogram. Two fast, robust and accurate techniques for retinal image registration are presented as a basic step in the development of an automated system for the arteriovenous passage time estimation. The mentioned techniques have their fundamentals on the Fourier transform and a parametric estimation based on the gradient of the quadratic error function and least squares computation.