Wavelet Based Image Watermarking using Error Correction Codes

Abstract

Information Technology has eased the duplication, manipulation and distribution of digital data in recent times which has resulted in the demand for safe ownership of digital images. A very crucial concern for the content owners and distributors is copyright protection and content authentication. The solution to these problems is digital watermarking, which is a technique for inserting information into an image and later extracted or detected for variety of purposes including identification and authentication. Watermark must have two most important properties: transparency and robustness. Transparency refers to the perceptual quality of the watermarked data. The watermark should be invisible over all types. Robustness is a most important property of watermark. It means that the watermark is still presented in the image and can be detected after distortion. Ideally, the amount of image distortion necessary to degrade the desired image quality should destruct and remove the watermark in the traditional watermarking without error correction code (ECC). So it is need to enhance the robustness of the embedded watermark by introducing the ECC, which can control the mistake and improve the reliability of data transmission in digital communication. With ECC appending some redundancy bits in the original embedded watermark, the error part of the extracted watermark can be corrected. In the proposed work, the embedding watermarks method based on the discrete wavelet transforms (DWT). Also, error correcting code (ECC) is applied to the ASCII representation of the text and the encoded text watermark is embedded. The performance of the proposed algorithm is evaluated in terms of imperceptibility and robustness against various attacks. The PSNR is used to measure the quality of the watermarked image. However, robustness of the extracted watermark is measured by BER. The proposed algorithm is robust against number of signal processing attacks without much degradation of the image quality.