Search

Steganography is the art and science of invisible communication. It is employed in different useful applications, like, safe circulation of secret data and Medical Imaging Systems. For most of the current steganography techniques, information hiding modifies almost all the cover components, which may negatively affect the visual quality of the image and increase the possibility of losing data after the possible attacks. This paper presents a new region based steganography technique, which hides data in the robust regions of the image. First, the Speeded-Up Robust Features (SURF) is used to find the most robust regions in the image. Then, the data embedding is achieved in a content-based manner by modifying the wavelet transform coefficients of those robust regions. Experimental results show the proposed algorithm allows hiding data invisibly with an accurate retrieval in the presence of lossy compression or noise. Moreover, the visual quality of the embedded image is high.

Digital image watermarking is proposed to overcome the problems of security, capacity and cost in health care management systems. Medical images, unlike most of images, require extreme care when embedding additional data within them because the additional information must not affect the image quality and readability. In order to overcome any misdiagnose caused by embedding data into medical images, lossless data hiding techniques have been developed. This paper presents a lossless watermarking technique for Ultrasound (US) images. The proposed technique adopts a high-capacity reversible data hiding scheme based on difference expansion (DE). It can be used to hide patient's data hiding and protecting the region of interest (ROI) with tamper detection and recovery capability. The experimental results show that the original image can be exactly extracted from the watermarked one in case of no tampering. In case of tampered ROI, tampered area can be localized and recovered losslessly.

In recent years, invisible digital watermarks have been proposed as a method for protecting copyrighted materials such as digital images. Due to its characteristics, one of the problems in digital image watermarking is to decide which technique should be used to hide in an image as many bits of information as possible while ensuring that the embedded watermark can be correctly extracted at the detecting stage, even after various attacks. In this paper we study the effect of dividing the image into blocks and applying a watermarking scheme to each block as an individual image (block-based), and compare it with applying the same watermark to the entire image (non-block-based). Digital wavelet transform (DWT) combined with a proper quantization method is used in this paper and normalized correlation (NC) is used to compare between the two cases after applying number of standard attacks. The results show that block-based watermarking has slightly better performance than non-block-based watermarking.