Biometric technique has been implemented instead of conventional identification methods such as password in computer,
automatic teller machine (ATM), and entrance and exit management system. We propose a personal identification (PI)
system using color retinal fundus images which are unique to each individual. The proposed procedure for identification
is based on comparison of an input fundus image with reference fundus images in the database. In the first step,
registration between the input image and the reference image is performed. The step includes translational and rotational
movement. The PI is based on the measure of similarity between blood vessel images generated from the input and
reference images. The similarity measure is defined as the cross-correlation coefficient calculated from the pixel values.
When the similarity is greater than a predetermined threshold, the input image is identified. This means both the input
and the reference images are associated to the same person. Four hundred sixty-two fundus images including forty-one
same-person's image pairs were used for the estimation of the proposed technique. The false rejection rate and the false
acceptance rate were 9.9×10<sup>-5</sup>% and 4.3×10<sup>-5</sup>%, respectively. The results indicate that the proposed method has a higher
performance than other biometrics except for DNA. To be used for practical application in the public, the device which
can take retinal fundus images easily is needed. The proposed method is applied to not only the PI but also the system
which warns about misfiling of fundus images in medical facilities.