This paper presents a new robust watermarking scheme for color image based on a block probability in spatial domain. A binary watermark image is permutated using sequence numbers generated by a secret key and Gray code, and then embedded four times in different positions by a secret key. Each bit of the binary encoded watermark is embedded by modifying the intensities of a non-overlapping block of 8*8 of the blue component of the host image. The extraction of the watermark is by comparing the intensities of a block of 8*8 of the watermarked and the original images and calculating the probability of detecting '0' or '1'. Tested by benchmark Stirmark 4.0, the experimental results show that the proposed scheme is robust and secure against a wide range of image processing operations.
This paper presents a novel multiple digital watermarking technique for the copyright protection of digital color images. In order to improve the robustness against cropping attacks, a binary watermark image is divided into four parts. Each is encrypted by a secret key and embedded into different regions of the blue component of the color image in the spatial domain. Watermark extraction is based on the comparisons between the original intensity pixel values and the corresponding watermarked intensity pixel values in blocks of size 8 × 8. The watermark-extracted bits are determined using the probabilities of detecting bit ‘1’ or bit ‘0’. The watermark can be extracted in several parts depending on the size of the host image, but only four of these are selected by a correlation coefficient detector and used to reconstruct the extracted watermark. Experimental results show that the proposed scheme successfully makes the watermark perceptually invisible and robust for a wide range of attacks, including JPEG-loss compression, median filtering, low pass filtering, rotation, rotation-scaling, rotation-crop, image cropping, image scaling, and self-similarity attacks
The robustness of watermarks to geometric attacks is viewed as an issue of great importance. Indeed, it constitutes one of the most challenging design requirements for watermarks. This study proposes a robust image watermarking scheme using visually significant feature points and image normalisation. In order to tackle the issue of geometric distortions, the authors adopt a feature extraction method based on end-stopped wavelets to extract significant geometry preserving feature points, which are shown to be robust against various types of common signal processing and geometric attacks. These feature points can be used as synchronisation marks between watermark embedding and detection. The watermark is embedded into non-overlapping normalised circular images, which are determined by feature points. Rotation invariance is achieved via image normalisation. The watermark embedding process is performed by modifying low-frequency coefficients of discrete cosine transform blocks, which are randomly selected using a secret key. Moreover, the security of the scheme is further guaranteed by an image-dependent key. The proposed scheme is blind as the original image is not required at the watermark detection. Experimental results show that the proposed scheme is robust against geometric attacks as well as common signal processing attacks and outperforms related techniques found in the literature. © 2012 © The Institution of Engineering and Technology
This paper proposes novel robust multiple watermarking technique for color images in spatial domain. The host image is divided into four different regions. Each region consists of four 128*128 blocks in order to hide a watermark. The watermark is a binary image, encrypted and embedded into different regions of the blue component of the host image by altering intensity values of the selected region. Five watermarks can be extracted by comparing the intensities of the selected region of the original image with the corresponding region of the watermarked image. The extracted watermark bits can be determined by calculating the probability of detecting '0' or '1'. Only one watermark will be selected or built from the five extracted watermarks according to the highest value of the normalized cross correlation (NCC). The proposed watermarking technique is shown to be robust for a wide range of attacks,
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