Further, these copy-paste image forensic techniques which are also called as image forgery detection techniques are categorized under two heads:
1) Block-based and
2) Keypoint based techniques. In this paper, we propose a common type of pixel based forensic technique called as copy-paste image forgery. We propose a blind digital image forensic method for image authentication so as to know whether the image is an authentic or a forged one. We have used block based approach to detect forgeries and used NCC as a basic tool to detect the forged regions.