Hybrid retinal image registration using phase correlation

Abstract

This paper deals with registration of retinal images, which were taken by high-resolution digital colour fundus cameras. The proposed method describes successful application of phase correlation method. It combines several basic steps — global correction of shift, rotation and scaling, detection of landmarks, their correspondences and finally image registration using second-order polynomial model. The method is tested on two sets of images. The first set contains images from the diabetic patients where many retinal pathologies can disturb the registration process. The second set contains images from healthy subjects, which were acquired by different illumination conditions. The method was evaluated using four different criteria - tree objective and one subjective. These criteria are also compared. The achieved registration accuracy of the landmarks position error is 1·13 and 0·93 pixels for respective image sets. Finally, the simple scheme for retinal pathology visualisation of registered fundus pairs is presented.

Keywords:

• retinal imaging
• image registration
• phase correlation
• feature extraction
• segmentation
• visualisation

This work has been supported by the national research centre DAR project no. 1M0572 coordinated by the Institute of Information Theory and Automation, Academy of Science and partly also by the institutional research frame no. MSM 0021630513; both grants sponsored by the Ministry of Education of the Czech Republic. The authors highly acknowledge the cooperation with Ophthalmology Clinic at the Erlangen University Hospital in Germany and cooperation with Ophthalmology Clinic MUDr. Tomas Kubena in Zlin, Czech Republic.