Watermark is an invisible type of signature embedded inside an image to show authenticity or proof of ownership. Watermark technique have been widely applied in various fields to protect the image against tampering. Therefore watermark algorithm have been developed to discover the tampered area and recover the lost information. This paper include source coder, channel code parity bit and check bit. Watermark technique aim to accomplish the task of tamper localization and error concealment. To easy use and analysis on computers, analog images are transformed to digital file format by digital encoding techniques. Watermarking is an information hiding technique that embeds watermark into the host image for copyright protection or integrity authentication. Fragile watermarking is used for both authentication and localization of tampered zone. The reference bits can protect against tampering by channel coder. The technique work by dividing an image into blocks and each block can be watermarked with a transparent watermark that sensitively depends on a secret key.
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