Shoulder surfing attack is happened in many places all over the world. To avoid the shoulder surfing attack Image Based Authentication Using Illusion-Pin (IBAUIP) method has been proposed. In this pin entry system using hybrid images of the two blended keypads in single digit. Every authentication the keypad is shuffled. The pin numbers are arranged in different order. The hackers cannot recognize or recall the user pin number and the IBAUIP model provides more security for authentication. In this IBAUIP model is used to perform the efficiency with human perception as parameter. The measures of this parameter performed with the existing method.