Chaotic model based semi fragile watermarking using integer transforms for digital fundus image authentication

This paper proposes a new reversible, imperceptible, semi fragile watermarking scheme for the authentication of digital fundus images that satisfies eight mandatory requirements. They are reversible, tamper detection, localization of modification, imperceptibility, capacity, complete blind detection, semi fragility and security. The proposed scheme generates the watermark dynamically using chaotic system and it is embedded using integer transform in reversible way. It precisely locates the tampering areas in the images and detects the watermark in complete blind approach without using the knowledge of both original image and watermark. It is found subjectively that 30,000 bits is the best size of the watermark for the proposed scheme to ensure the security and it is achieved for the PSNR value of around 60 dB at an average by retaining good level of imperceptibility. The proposed scheme is sensitive to the jittering, geometrical and filtering attacks and it modifies around 40 % of bits in the watermark for jittering and geometrical attacks, around 45 % of the bits in the watermark for filtering attacks to authenticate the images.