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Roopa Jayasingh, J.
- Digital Watermarking using Least Significant Bit Insertion Method
Authors
Source
Digital Image Processing, Vol 5, No 2 (2013), Pagination: 76-85Abstract
In this paper a new non-blind LSB (Least Significant Bit) based gray scale image watermarking technique is used. This new algorithm is used LSB , by inserting the binary values of the watermark and shifting the watermark according to the higher or lower bits of pixel coordinates of the image before embedding the watermark. Here the cover image is of size 128x128 and the watermark size is 32x32.The embedding and Extraction algorithm is applied to each bit inserted images separately. After the embedding, the watermarked images are tested against some attacks. The proposed technique is expected to show a great ability to preserve the watermark against these attacks. The watermark quality can be measured by calculating the MSE, PSNR, SSIM values. For a good embedding the PSNR value should be high and the SSIM should be also higher. SSIM values are between [1,0]. Using this technique, good watermark embedding can be achieved; also it shows high imperceptibility and robustness of the embedded watermark.
Keywords
Least Significant Bit, Grayscale Image, MSE, PSNR, SSIM, Imperceptibility, and Robustness.
- Nonblind Watermarking for Color Images using DWT Hybrid Technique
Authors
1 Department of Electronics and Communication Engineering, Karunya University, Coimbatore, IN
Source
Digital Image Processing, Vol 5, No 2 (2013), Pagination: 86-91Abstract
Watermarking is the method of embedding data into multimedia content such as image, audio and video file for the purpose of copyright protection. The watermarking technique has developed greatly and became the powerful tool for protection of multimedia contents. A robust nonblind watermarking scheme has been proposed and images are exposed to various attacks. This method uses DWT-DCT combination for effective watermarking. The color image is converted to Luminance (Y), Intensity (I) and Hue (Q) components. Haar wavelet transform is used for the decomposition of luminance component. Three level decomposition of DWT is performed here. The color image of size 512x512 is taken as the cover image and watermark of size 32x32 is embedded in cover image. Robustness and imperceptibility are the two main factors influencing the quality of the watermarked image. The strength of the watermarking scheme has been evaluated in terms of metrics like PSNR and Correlation coefficient after exposing the embedded image to a wide range of aggressive image processing operations like noise, rotation, filtering, compression etc. The watermark is retrieved after each attack. The DWT provides flexibility in providing the choice of embedding location while the DCT provides the necessary robustness towards intentional and unintentional attacks. A Composite payload is used and the effect of variation of payload over the image quality is also studied.