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Abstract: With the advanced technologies in the area of Engineering the World has become a smaller place and communication is in our finger tips. The multimedia sharing traffic through electronic media has increased tremendously in the recent years with the higher use of social networking sites. The statistics of amount of images uploaded in the internet per day is very huge. Digital Image security has become vulnerable due to increase transmission over non-secure channel and needs protection. Digital Images play a crucial role in medical and military images etc. and any tampering of them is a serious issue. Several approaches are introduced to authenticate multimedia images. These approaches can be categorized into fragile and semi-fragile watermarking, conventional cryptography and digital signatures based on the image content. The aim of this paper is to provide a comparative study and also a survey of emerging techniques for image authentication. The important requirements for an efficient image authentication system design are discussed along with the classification of image authentication into tamper detection, localization and reconstruction and robustness against image processing operation. Furthermore, the concept of image content based authentication is enlightened.
Keywords: Image Authentication, Forgery, Watermarking, Digital image signature, Hashing.
1. Introduction
Information is facts provided or learned about something or someone. Exploitation of information can be used for profiteering. Traditionally, voice or manuscripts are used for communication but in the modern era information can travel miles. Images are transmitted through unsecure medias that are used for these communications and hence volatile to attacks and create a risk factor in area such as military, crime file, researches, medical diagnosis etc. Preprocessing operation such as quantization, compression, scaling, rotations may not change the semantic meaning of the image and thus identification of the image based on robustness is encouraged. Image Authentication is a mandatory in areas where image security is challenged. The basic requirements for an image authentication system are sensitivity, robustness, localization, recovery, security, portability and complexity. Some of the Mathematical Tools used in message authentication are modified for image authentication namely cryptography, digital signatures and hash functions. Image forensic can be identified by using some tools as pixel-based technique that detect statistical anomalies introduced at pixel level, format-based technique that leverage the statistical correlations introduced by...