15-11-2012, 01:40 PM
A Reversible visible watermarking scheme for Compressed images
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Abstract:
Visible Digital watermarking is a methodology which includes a concept of a steganography and cryptography which makes an application useful for copyright protection or preserving of ownership and duplication of data can be eradicated, which acts as a authentication or authorization of a data. The visible watermarking will be suspectable to quantization errors which cause the loss of data.
We propose a reversible visible watermarking technique which is suitable for lossy compressed images. Here we use discrete wavelet transformations for the process of image compression by which the watermark signal can be present in a low frequency region or azimuthal signal. The quality of a reverse signal can be measured with the help of mean square error and peak signal-to-noise ratio (PSNR). The loss of high frequency data can be preserved in high frequency bands of the resultant of discrete wavelet transformation (DWT). In this dwt technique a multi-bit watermark is embedded into the low frequency sub-band of a cover image by using alpha blending technique. The insertion and extraction of the watermark in the grayscale cover image is found to be simpler than other transform techniques. The proposed method is compared with the 1-level and 2-level. DWT based image watermarking methods by using statistical parameters such as peak-signal-to-noise-ratio (PSNR) and mean square error (MSE).
The reversible visible watermarking schemes are susceptible to quantization errors induced by lossy images and not applicable for high quality multimedia communications applications. In this reversible mechanism the information is restored at watermarked region using quantization. Hence superiority of the proposed scheme for compressed images where Peak Signal-to-Noise Ratio (PSNR) gains of up to 3dB. Now-a-days multimedia technologies have contributed to an extensive use of multimedia content in a various applications. However, the available multimedia editing software made the protection of ownership and prevention of unauthorized manipulation.