A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> We propose a lossless watermarking scheme, in a sense that the original image can be exactly recovered from the watermarked one, with the purpose of verifying the integrity and authenticity of medical images in PACS. Our embedding method includes imposing invertible modulations that induce low distortion level, as well as losslessly compressing the status of the original image and carrying such information in the watermarked image. Digital signature of the whole image is embedded for verifying the integrity of the image. An identifier also presented in electronic patient record (EPR) is embedded for verifying the authenticity by simultaneously processing of the watermarked image and the EPR. Combining with fingerprint system, patient’s fingerprint information is further embedded into several image slices and then extracted for verifying the authenticity. No visual quality degradation is detected in the watermarked image. <s> BIB001 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> Within the expanding paradigm of medical imaging and wireless communications there is increasing demand for transmitting diagnostic medical imagery over error-prone wireless communication channels such as those encountered in cellular phone technology. Medical images must be compressed with minimal file size to minimize transmission time and robustly coded to withstand these wireless environments. It has been reinforced through extensive research that the most crucial regions of medical images must not be degraded and compressed by a lossless or near lossless algorithm. This type of area is called the Region of Interest (ROI). Conversely, the Region of Backgrounds (ROB) may be compressed with some loss of information to achieve a higher compression level. This type of hybrid coding scheme is most useful for wireless communication where the 'bit-budget' is devoted to the ROI. This paper also develops a way for this system to operate externally to the Joint Picture Experts Group (JPEG) still image compression standard without the use of hybrid coding. A multiple watermarking technique is developed to verify the integrity of the ROI after transmission and in the situation where there may be incidental degradation that is hard to perceive or unexpected levels of compression that may degrade ROI content beyond an acceptable level. The most useful contribution in this work is assurance of ROI image content integrity after image files are subject to incidental degradation in these environments. This is made possible with extraction of DCT signature coefficients from the ROI and embedding multiply in the ROB. Strong focus is placed on the robustness to JPEG compression and the mobile channel as well as minimizing the image file size while maintaining its integrity with the use of semi-fragile, robust watermarking. <s> BIB002 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> Medical image security can be enhanced using watermarking, which allows embedding the protection information as a digital signature, by modifying the pixel gray levels of the image. In this paper we propose a reversible watermarking scheme which guarantees that once the embedded message is read, alterations introduced during the insertion process can be removed from the image. Thereafter, original pixel gray levels of the image are restored. The proposed approach relies on estimation of image signal that is invariant to the insertion process, and permits to introduce a very slight watermark within the image. In fact, the insertion process adds or subtracts at least one gray level to the pixels of the original image. Depending on the image to be watermarked, in our case angiographic images of the retina, it is expected that such image alteration will not have any impact on the diagnosis quality, and consequently that the watermark can be kept within the image while this one is interpreted <s> BIB003 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> In this paper, we present a novel blind water- marking method with secret key by embedding ECG signals in medical images. The embedding is done when the original image is compressed using the embedded zero-tree wavelet (EZW) algorithm. The extraction process is performed at the decompression time of the watermarked image. Our algorithm has been tested on several CT and MRI images and the peak signal to noise ratio (PSNR) between the original and watermarked image is greater than 35 dB for watermarking of 512 to 8192 bytes of the mark signal. The proposed method is able to utilize about 15% of the host image to embed the mark signal. This marking percentage has improved previous works while preserving the image details. transmission overheads as well as helping for computer aided diagnostics system. In this paper we present a new watermarking method combined with the EZW-based wavelet coder. The principle is to replace significant wavelet coefficients of ECG signals by the corresponding significant wavelet coefficients belong- ing to the host image which is much bigger in size than the mark signal. This paper presents a brief introduction to watermarking and the EZW coder that acts as a platform for our watermarking algorithm. <s> BIB004 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> This paper presents a lossless watermarking scheme in the sense that the original image can be exactly recovered from the watermarked one, with the purpose of verifying the integrity and authenticity of medical images. In addition, the scheme has the capability of not introducing any embedding-induced distortion in the region of interest (ROI) of a medical image. Difference expansion of adjacent pixel values is employed to embed several bits. A region of embedding, which is represented by a polygon, is chosen intentionally to prevent introducing embedding distortion in the ROI. Only the vertex information of a polygon is transmitted to the decoder for reconstructing the embedding region, which improves the embedding capacity considerably. The digital signature of the whole image is embedded for verifying the integrity of the image. An identifier presented in electronic patient record (EPR) is embedded for verifying the authenticity by simultaneously processing the watermarked image and the EPR. Combining with fingerprint system, patient’s fingerprint information is embedded into several image slices and then extracted for verifying the authenticity. <s> BIB005 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> Problem statement: Digital watermarking provides security to medical images. Watermarking in Region Of Interest (ROI) however distorts medical images but it is known that the resulting loss of fidelity is visually imperceptible. Approach: Clinical assessment will objectively evaluate the distortion on medical images to see whether or not medical diagnosis is altered. We used 75 medical images consisting of x-rays, ultrasound and CT scans. Digital watermarking was inserted in ROI and ROI/Region Of Non Interest (RONI) in all of them. Three assessors were randomly assigned 225 images, each receiving 75, a mixture of watermarked and non watermarked images. Results: Chi square test was used and p<0.05 was considered significant. There was no significant difference between original images and those watermarked in ROI or ROI/RONI. There was no comment on image quality in all the images assessed. Conclusion/Recommendations: Digital watermarking does not alter medical diagnosis when assessed by clinical radiologists. The quality of the watermarked images was also unchanged. <s> BIB006 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> Authenticating medical images using watermarking techniques has become a very popular area of research, and some works in this area have been reported worldwide recently. Besides authentication, many data-hiding techniques have been proposed to conceal patient’s data into medical images aiming to reduce the cost needed to store data and the time needed to transmit data when required. In this paper, we present a new hybrid watermarking scheme for DICOM images. In our scheme, two well-known techniques are combined to gain the advantages of both and fulfill the requirements of authentication and data hiding. The scheme divides the images into two parts, the region of interest (ROI) and the region of non-interest (RONI). Patient’s data are embedded into ROI using a reversible technique based on difference expansion, while tamper detection and recovery data are embedded into RONI using a robust technique based on discrete wavelet transform. The experimental results show the ability of hiding patient’s data with a very good visual quality, while ROI, the most important area for diagnosis, is retrieved exactly at the receiver side. The scheme also shows some robustness against certain levels of salt and pepper and cropping noise. <s> BIB007 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> Watermarking in medical images is a new area of research. It has the potential of being a value-added tool for medical confidentiality protection, patient-related information hiding, and information retrieval. Medical image watermarking requires extreme care when embedding additional data within the medical images because the additional information must not affect the image quality as this may cause misdiagnosis. In this paper we present a scheme that depends on the extraction of the ROI (region of interest) and its use as a watermark to be embedded twice; first as a robust watermark in the RONI (region of non interest) in the wavelet domain and again as a fragile watermark in the ROI in the spatial domain. Moreover multiple watermarks such as the physician's digital signature and EPR (Electronics Patient Record) are embedded in the RONI in wavelet domain depending on a private key. We compare this scheme by another one that we presented before to show the robustness of new scheme. In our work we use MRI brain images with a brain tumor as the ROI. The experimental results showed that the watermarked image is robust to JPEG compression, ROI removal, and addition of an additional tumor to the image and some geometrical attacks; lowpass and median filtering and some types of noise as; Gaussian, Poisson, Salt and Pepper and finally Speckle. <s> BIB008 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> Medical Image data require strict security, confidentiality and integrity when transmitted from one hospital to another hospital. This can be achieved by adopting the procedures which can guarantee the image quality as well as secrecy of patient data to unauthorized users. To achieve these requirements we have proposed a multiple watermarking method. The scheme embeds robust watermark in region of non interest (RONI) for achieving security and confidentiality. While integrity control is achieved by inserting fragile watermark in region of interest ROI. Since ROI in the medical image is important from diagnosis point of view so it must be preserved. In order to avoid the distortion caused in ROI due to watermark insertion process, original ROI data is first separated and embedded outside the ROI. This will help in recovery of original ROI at the receiving end in contrast to the techniques reported in the literature which do not guarantee the integrity of the ROI after watermarking process. The image visual quality as well as tamper localization has been evaluated. We have used weighted peak signal to noise ratio (WPSNR) for measuring image quality after watermarking. <s> BIB009 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> This paper discusses the security problem of integrality and reality authentication in medical image, and introduces digital signature technology based on RSA public cryptosystem in brief. It analyzes the merit and insufficiency of digital signature technology. Considering the specialty of medical image, it brings forward integrating reversible digital watermarking with digital signature to form an authentication system. Then, the scheme of the system is carried through. Finally, the system is designed and implemented by using the c# software. The experiment results show that the proposed system has good imperceptibility. It effectively solves the problem of complete integrity and reality authentication of medical image. <s> BIB010 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> Medical image is usually comprised of region of interest (ROI) and region of non interest (RONI). ROI is the region that contains the important information from diagnosis point of view so it must be stored without any distortion. We have proposed a digital watermarking technique which avoids the distortion of image in ROI by embedding the watermark information in RONI. The watermark is comprised of patient information, hospital logo and message authentication code, computed using hash function. Earlier BCH encryption of watermark is performed to ensure inaccessibility of embedded data to the adversaries. <s> BIB011 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> With the broad application of electronic management of medical records, the integrality and reality authentication of medical image in hospital information system have been in front us. In order to solute these problems, a novel watermarking image authentication based on DSA is presented. In this paper, we introduce digital signature arithmetic (DSA), and analyze the advantage and shortage of DSA. Then, considering the specialty of medical image, it brings forward integrating reversible digital watermarking with digital signature to form an authentication system. Finally, the system is designed and implemented by using the c# language. The experiment results show that the medical image is difficult to tamper. It effectively solves the problem of complete integrity and reality authentication of medical image. <s> BIB012 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> The Picture Archiving and Communication System(PACS) was introduced for computerization of the medical system and telediagnosis between the hospital. It is becoming possible to create, store, and transmit medical images via PACS. There has been a growing interest in protecting medical images with an enormous amount of information. To improve transmission speed among the hospitals, the medical image should be compression JPEG 2000 by high compression ratio. This paper proposes an algorithm that utilizes both JPEG 2000 and robust watermarking for protection and compression of the medical image. With the proposed algorithm, it takes considerably less time to do JPEG 2000 and watermarking than when they are done separately. Based on the experiment results, it takes 0.72 second for the proposed algorithm and 1.11 second when they are done separately. We confirmed that the proposed algorithm was faster than when they are done separately. <s> BIB013 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> In this article, a new fragile, blind, high payload capacity, ROI (Region of Interest) preserving Medical image watermarking (MIW) technique in the spatial domain for gray scale medical images is proposed. We present a watermarking scheme that combines lossless data compression and encryption technique in application to medical images. The effectiveness of the proposed scheme, proven through experiments on various medical images through various image quality measure matrices such as PSNR, MSE and MSSIM enables us to argue that, the method will help to maintain Electronic Patient Report(EPR)/DICOM data privacy and medical image integrity. <s> BIB014 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> Enforcing protection of medical content becomes a major issue of computer security. Since medical contents are more and more widely distributed, it is necessary to develop security mechanism to guarantee their confidentiality, integrity and traceability in an autonomous way. In this context, watermarking has been recently proposed as a complementary mechanism for medical data protection. In this paper, we focus on the verification of medical image integrity through the combination of digital signatures with such a technology, and especially with Reversible Watermarking (RW). RW schemes have been proposed for images of sensitive content for which any modification may affect their interpretation. Whence, we compare several recent RW schemes and discuss their potential use in the framework of an integrity control process in application to different sets of medical images issued from three distinct modalities: Magnetic Resonance Images, Positron Emission Tomography and Ultrasound Imaging. Experimental results with respect to two aspects including data hiding capacity and image quality preservation, show different limitations which depend on the watermark approach but also on image modality specificities. <s> BIB015 </s> A Review of Medical Image Watermarking Requirements for Teleradiology <s> Digital Watermarking Versus Other Security Measures/Tools <s> Medical image data require strict security, confidentiality and integrity. To achieve these stringent requirements, we propose a hybrid watermarking method which embeds a robust watermark in the region of non-interest (RONI) for achieving security and confidentiality, while integrity control is achieved by inserting a fragile watermark into the region of the interest (ROI). First the information to be modified in ROI is separated and is inserted into RONI, which later is used in recovery of the original ROI. Secondly, to avoid the underflow and overflow, a location map is generated for embedding the watermark block-wise by leaving the suspected blocks. This avoids the preprocessing step of histogram modification. The image visual quality, as well as tamper localization, is evaluated. We use weighted peak signal to noise ratio for measuring image quality of watermarked images. Experimental results show that the proposed method outperforms the existing hybrid watermarking techniques. <s> BIB016
Digital watermarking has some unique advantages for teleradiology, although few existing security measures/tools may serve its other objectives together, for example, encryption, cryptographic hash function (e.g., MAC, DS, etc.), perceptual hashing, etc. Following our previous discussion on watermarking and other comparable security measures/ tools, an extensive comparison among them based on various key properties and requirements of medical image applications is made and presented in Table 4 . As Table 4 illustrates, cryptographic/perceptual hashing has no impact on quality of the host-signal, and is suitable for legacy content, but they are either bit-sensitive (for cryptographic hash functions) or need access to a central database to search for a match with a pre-computed hash (for perceptual hashing), whereas research suggests that a carefully designed watermarking scheme does not alter medical diagnosis BIB006 . Although watermarking has an impact, more or less, on perceptual quality and difficulties with legacy content, Guo and Zhuang BIB001 suggested three ways to overcome the distortion induced in images by watermark embedding. They are: (1) defining acceptable range of distortion for watermarking;  separating an image into protection zone and insertion zone such as ROI (region of interest) and RONI (region of noninterest); and (3) considering watermarking as an invertible manner to recover the original image at the watermark decoder site. Hence, ROI indicates the region significant for diagnosis and other clinical uses, and RONI indicates the complementary region of ROI, which has lesser or almost no significance in diagnosis. Defining acceptable range of distortion for watermark embedding through clinical validation is expensive, which is applied by Zain et al. BIB006 . In contrast, separation of ROI and RONI in medical images is not straightforward and may require the interaction/approval of doctor/radiologist. In addition, making such separation is sometimes very difficult, although it is applied in several watermarking schemes BIB016 BIB007 BIB008 . Besides, developing reversible watermarking is promising for medical image application with taking no risk for sacrificing the diagnostic accuracy, although computational properties may incur additional complexity in different processing domains. Additionally, Coatrieux et al. BIB003 discussed two limitations of reversible watermarking: (1) It imposes the watermark removal before the diagnosis, and (2) it assumes a secured environment because, once the watermark is removed, the image is not protected anymore like in cryptography. All these suggest that a combination of suitable type of watermarking schemes, where the concept of multiple watermarking stems from, can be developed in order to address the rising security problems of medical images in teleradiology BIB008  BIB002 BIB009 . Studies also show that incorporation of asymmetric encryption and lossless compression can help attain additional confidentiality, nonrepudiation property, high embedding capacity BIB014 BIB001 108] . Watermarking allows using DS or perceptual hashing for appropriate applications BIB005  BIB015 BIB010 . Watermarking systems have room for employing encryption for the additional confidentiality of metadata (e.g., in generating watermark). Memon et al. BIB011 proposed a digital watermarking scheme, in which watermark is comprised of patient information, hospital logo, and message authentication code, computed using hash function. To ensure inaccessibility of embedded data to the adversaries, BCH encryption of watermark is performed there. For the same purpose, Li-Qun et al. introduced DSA BIB012 and digital signature technology based on RSA public cryptosystem BIB010 , integrating reversible digital watermarking with digital signature to form an authentication system. Furthermore, a few of recent studies show the use of a compression technique for attaining the embedding capacity requirements of watermarking. Nambakhsh et al. BIB004 presented a watermarking method on several computed tomography (CT) and magnetic resonance (MRI) images, where the original image is compressed using the zero-tree wavelet (EZW) algorithm. Raul et al.  used Huffman compression and RC4 method that respectively compress and encrypt the metadata in a blind watermarking scheme. Kundu et al. BIB014 presented a watermarking scheme that combines lossless data compression and advanced encryption standard for encryption of medical images. In addition, Sung-Jin et al. BIB013 proposed an algorithm that utilizes both JPEG 2000 and robust watermarking for protection and compression of the medical image. Thus, depending on the application, a choice for the appropriate mixture of various technologies can be made to devise a suitable watermarking system for teleradiology.