Biometric voting system

Question

i have made a biometric voting system as my final year project . the project has two forms , the onc can access only admin while the user can access the user form . the admin first register candidate and voter with their thumb print image in database. on voting time the voter put his id number to confirm whether h//she exists or not . then he upload his thumb print image and check it whether it's similar with the database or not. but i've no idea how the image will be match from the database image. kindly if anyone wants to help then do let me know. my programming is not advaced for image processing. Thankyou