Advancements in science and technology have introduced the need to protect data, authenticate data, integrate data, assert ownership, content labelling and security. Digital Watermarking schemes protect all forms of digital data. Digital Image Watermarking can be applied to gray scale, halftone, color, medical and 3D images. The process of watermarking can be broadly classified into three phases namely embedding, attacking, and decoding for typical scenarios. Some of the watermarking schemes adopted in the past include vector quantization, spread spectrum, SVD, DCT, DFT, etc. It was observed that the spread spectrum was more robust and it had also been applied for patenting. In spite of this, the method could not withstand high amplitude noise. Hence, later DCT, DFT and Wavelets were used. These schemes were not robust to collusion attacks. In this review, we have identified the embedding and detection schemes of the existing watermarks over the past decade and analyzed the robustness of each of these methods. The different parameters considered to analyze the performance of the existing watermarking schemes are also discussed. Research under watermarking is a great field of interest involving multimedia security, forensics, data authentication and digital rights protection. This paper will be useful for researchers to implement a robust watermarking scheme.
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