Fragile Watermarking of Medical Image for Content Authentication and Security

Currently in the health environment, medical images are a very crucial and important part of the medical information because of the large amount of information and their disposal two-dimensional. Medical images are stored, transmitted and recovered on the network. The images users await efficient solutions to preserve the quality and protect the integrity of images exchanged. In this context, watermarking medical image has been widely recognized as an appropriate technique to enhance the security, authenticity and content verification. Watermarking image may bring elements of complementary research methods of classical cryptography. The objective of this paper is to develop a method to authenticate medical images to grayscale, detect falsified on these image zones and retrieve the original image using a blind fragile watermarking technique. We propose a method based on the discrete wavelet transform (DWT) for the application of content authentication. In our algorithm, the watermark is embedded into the sub-bands detail coefficient. The subbands coefficients are marked by adding a watermark of the same size as three sub-bands and a comparison of embedding a watermark at vertical (LH), horizontal (HL) and diagonal (HH) details. We tested the proposed algorithm after applying some standard types of attacks and more interesting. The results have been analyzed in terms of imperceptibility and fragility. Tests were conducted on the medical images to grayscale and color size 512 × 512

Reversible watermarking scheme with image-independent embedding capacity

Permanent distortion is one of the main drawbacks of all the irreversible watermarking schemes. Attempts to recover the original signal after the signal passing the authentication process are being made starting just a few years ago. Some common problems, such as salt-and-pepper artefacts owing to intensity wraparound and low embedding capacity, can now be resolved. However, some significant problems remain unsolved. First, the embedding capacity is signal-dependent, i.e., capacity varies significantly depending on the nature of the host signal. The direct impact of this is compromised security for signals with low capacity. Some signals may be even non-embeddable. Secondly, while seriously tackled in irreversible watermarking schemes, the well-known problem of block-wise dependence, which opens a security gap for the vector quantisation attack and transplantation attack, are not addressed by researchers of the reversible schemes. This work proposes a reversible watermarking scheme with near-constant signal-independent embedding capacity and immunity to the vector quantisation attack and transplantation attack

Digital watermarking in medical images

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 05/12/2005.This thesis addresses authenticity and integrity of medical images using watermarking. Hospital Information Systems (HIS), Radiology Information Systems (RIS) and Picture Archiving and Communication Systems (P ACS) now form the information infrastructure for today's healthcare as these provide new ways to store, access and distribute medical data that also involve some security risk. Watermarking can be seen as an additional tool for security measures. As the medical tradition is very strict with the quality of biomedical images, the watermarking method must be reversible or if not, region of Interest (ROI) needs to be defined and left intact. Watermarking should also serve as an integrity control and should be able to authenticate the medical image. Three watermarking techniques were proposed. First, Strict Authentication Watermarking (SAW) embeds the digital signature of the image in the ROI and the image can be reverted back to its original value bit by bit if required. Second, Strict Authentication Watermarking with JPEG Compression (SAW-JPEG) uses the same principal as SAW, but is able to survive some degree of JPEG compression. Third, Authentication Watermarking with Tamper Detection and Recovery (AW-TDR) is able to localise tampering, whilst simultaneously reconstructing the original image