A Color Image Watermarking Scheme Based On QR Factorization, Logistic and Lorentz Chaotic Maps

Most of the existing color image watermarking schemes use grayscale or binary image as watermark because color image watermark has more data than grayscale or binary watermark. Therefore, it is a challenging issue to design a color image-watermarking scheme. This paper proposes a novel color image watermarking scheme to embed color image watermark into color host image. In watermarking schemes, first divide the host and watermark image into non-overlapping blocks, apply the Discrete Cosine Transformation (DCT) on each blocks of both watermark, and host image. After that QR Factorization, apply on the each blocks of watermark. In this paper, Logistic and Lorentz chaotic maps are usedfor estimating the embedding strength and location. The experimental results reveal that this watermarking scheme is robust against different image processing attacks viz. cropping, contrast adjustment and coloring

Watermark in color image

[[abstract]]There is an increasing number of products to be saved in digital form. In the digital world, we can preserve products forever, but there are also disadvantages such as easy copying. The watermark is an important protection method in digital media. When a media is publicly available or put on a network, it is very easy to copy or be misappropriated. The author can prove ownership by using an open algorithm and security key to extract the watermark. Therefore, a watermark technique must resist attacks and cannot influence image quality. We propose an image watermark technique based on the spatial domain in a color image. We present experimental results which prove that our method can resist certain attacks.[[notice]]補正完畢[[notice]]補正完畢[[conferencetype]]國際[[conferencedate]]20021101~2002110

Copyright Protection of Color Imaging Using Robust-Encoded Watermarking

In this paper we present a robust-encoded watermarking method applied to color images for copyright protection, which presents robustness against several geometric and signal processing distortions. Trade-off between payload, robustness and imperceptibility is a very important aspect which has to be considered when a watermark algorithm is designed. In our proposed scheme, previously to be embedded into the image, the watermark signal is encoded using a convolutional encoder, which can perform forward error correction achieving better robustness performance. Then, the embedding process is carried out through the discrete cosine transform domain (DCT) of an image using the image normalization technique to accomplish robustness against geometric and signal processing distortions. The embedded watermark coded bits are extracted and decoded using the Viterbi algorithm. In order to determine the presence or absence of the watermark into the image we compute the bit error rate (BER) between the recovered and the original watermark data sequence. The quality of the watermarked image is measured using the well-known indices: Peak Signal to Noise Ratio (PSNR), Visual Information Fidelity (VIF) and Structural Similarity Index (SSIM). The color difference between the watermarked and original images is obtained by using the Normalized Color Difference (NCD) measure. The experimental results show that the proposed method provides good performance in terms of imperceptibility and robustness. The comparison among the proposed and previously reported methods based on different techniques is also provided

A New Double Color Image Watermarking Algorithm Based on the SVD and Arnold Scrambling

We propose a new image watermarking scheme based on the real SVD and Arnold scrambling to embed a color watermarking image into a color host image. Before embedding watermark, the color watermark image W with size of M×M is scrambled by Arnold transformation to obtain a meaningless image W~. Then, the color host image A with size of N×N is divided into nonoverlapping N/M×N/M pixel blocks. In each (i,j) pixel block Ai,j, we form a real matrix Ci,j with the red, green, and blue components of Ai,j and perform the SVD of Ci,j. We then replace the three smallest singular values of Ci,j by the red, green, and blue values of W~ij with scaling factor, to form a new watermarked host image A~ij. With the reserve procedure, we can extract the watermark from the watermarked host image. In the process of the algorithm, we only need to perform real number algebra operations, which have very low computational complexity and are more effective than the one using the quaternion SVD of color image