Atlas-based segmentation of neck muscles from MRI for the characterisation of Whiplash Associated Disorder

Whiplash-associated disorder (WAD) is a commonly occurring injury that often results from neck trauma suffered in car accidents. However the cause of the condition is still unknown and there is no definitive clinical test for the presence of the condition. Researchers have begun to analyze the size of neck muscles and the presence of fatty infiltrates to help understand WAD. However this analysis requires a high precision delineation of neck muscles which is very challenging due to a lack of distinctive features in neck magnetic resonance imaging (MRI). This paper presents a novel atlas-based neck muscle segmentation method which employs discrete cosine-based elastic registration with affine initialization. Our algorithm shows promising results based on clinical data with an average Dice similarity coefficient (DSC) of 0.84±0.0004

Blind Video Watermarking for the Detection of Illegal Downloading of Video Content

Illegal distribution of a digital movie is a significant threat to the film industry. Currently, camcorder theft is the single largest source of video piracy and is one of the most significant problems facing movie studios and producers. Approximately ninety percent of the first versions available of illegally distributed new release films have been pirated using a digital camcording device in a movie theatre. With the advent of high-speed broadband Internet access, a pirated copy of a digital video can be easily distributed to a global audience for viewing online and downloading within just days of its release in theatres. Even though there are strict laws in many countries against video piracy, they have proven to be ineffective and it has not been possible to prevent this practice. Therefore, protecting the copyright of digital video content is becoming very important. As the popularity of 3D videos is increasing daily, concern over protecting them from unauthorised distribution is also growing.Digital video watermarking is a possible means of limiting this type of digital distribution. This is the process of embedding extra information in a host video signal so that the watermark is imperceptible and, in a blind detection system, it is robust and difficult to remove or alter. In existing watermarking methods, the watermark is usually embedded in the luminance (Y) channel in a YUV representation of a video frame which affects imperceptibility. In addition, none of the existing techniques are robust to the combination of commonly used attacks, including lossy compression, upscaling, rotation, cropping, downscaling in resolution, aspect ratio change, frame rate conversion and camcording. The key focus of this work is to design a digital video watermarking algorithm for both 2D and 3D content that can mitigate their associated challenges.In the first part of this dissertation, a blind digital video watermarking algorithm is proposed. The watermark is embedded in one level (low-frequency coefficients) of the dual-tree complex wavelet transform (DT CWT) of the chrominance (U) channel, and extracted using the same key and level used for embedding. This embedding in the U channel provides a high-quality watermarked video and the DT CWT enhances its robustness to geometric attacks, such as scaling, rotation and cropping, due to its approximate shift invariance characteristic. To evaluate the overall performance of the proposed method for H.264/AVC compression and geometric attacks, an experimental comparison of the proposed U channel embedding approach, Y channel embedding and two existing methods is undertaken. The experimental results verify the efficacy of the proposed algorithm.The downscaling in resolution of a frame in the spatial domain removes the high-frequency information. As a result, the watermark and low-frequency coefficients in the DT CWT domain spread into the new high-frequency coefficients. In such a situation, watermark detection results in a false negative error if it extracts from only the level used for embedding. Therefore, in the second part of this work, an extension of the first method extracts the watermark from any level(s) of the DT CWT decomposition depending on the resolution of the downscaled version of the watermarked frame. However, this method still suffers in terms of temporal synchronisation attacks, such as frame rate conversion, as the embedding key is required for detection. To overcome this limitation, the watermark of a frame is extracted from the information of that frame without using the key used during its embedding. The experimental results show that the proposed method is not only robust to temporal synchronisation attacks and downscaling to an arbitrary resolution but also upscaling, rotation, cropping, lossy compression, camcording, watermark estimation remodulation, temporal frame averaging and multiple watermark embedding.In the last part of this research, the emphasis is on protecting a depth-image based rendered (DIBR) 3D video. The proposed scheme embeds the watermark in both the chrominance channels (U and V) of the centre view using the DT~CWT. Then, the synthesised watermarked stereo pairs (left and right views) are generated at the decoder from both the depth map and watermarked centre view using the DIBR process. The watermark is extracted independently from the centre, left and right views which can be distributed individually as 2D content. The quality of the watermarked 3D video is evaluated by a subjective test and compared with that of a DIBR 3D image watermarking algorithm. The experimental results demonstrate that the proposed scheme provides superior performance to those of state-of-the-art approaches in terms of Gaussian noise addition, baseline distance adjustment and 3D camcording, as well as the attacks considered in the previous part of this study for 2D video

Inter-Subject Image Registration of Clinical Neck MRI Volumes using Discrete Periodic Spline Wavelet and Free Form Deformation

This paper presents a framework for inter-patient image registration which uses a multi-thresholds, multi-similarity measures and multi-transformations based on compactly supported spline and discrete periodic spline wavelets (DPSWs) using the Gauss-Newton gradient descent (GNGD) and gradient descent (GD) optimization methods. Our primary intellectual contribution is incorporating DPSWs in the transformation while another includes fusing out-of-range concept in a surface matching technique which is implemented by a multi-transformations and multi-similarity measures. In particular, as a true deformation cannot be achieved by single combination of transformation, similarity measure (SM) and optimization of a registration process, a moving image is required to be brought within the range of a registration. On the other hand, the surface matching technique involves an edge position difference (EPD) SM in which coarse to fine surfaces are matched using multiple thresholds with a spline-based free from deformation (FFD) method. The registration experiments were performed on 3D clinical neck magnetic resonance (MR) images, with the results showing that our proposed method provides good accuracy and robustness

Stereo vision-based 3D positioning and tracking

Khyam, MO ORCiD: 0000-0002-1988-2328The evolution of technologies for the capture of human movement has been motivated by a number of potential applications across a wide variety of fields. However, capturing human motion in 3D is difficult in an outdoor environment when it is performed without controlled surroundings. In this paper, a stereo camera rig with an ultra-wide baseline distance and conventional cameras with fish-eye lenses is proposed. Its cameras provide a wide field of view (FOV) which increases the coverage area and also enables the baseline distance to be increased to cover the common area required for both cameras’ views to perform as a stereo camera. We propose a passive marker-based approach to track the motion of the object. In this method, an adaptive thresholding method is applied to extract each small pink polyester marker from the video frames. As the cameras have fish-eye lenses, it is difficult to estimate the depth information using a pinhole camera model. We use a unique method to restore the 3D positions by developing a relationship between the pixel dimensions and distances in an image and real world coordinates. In this paper, occlusion detection is considered because, in the marker-based capturing of articulated human kinematics, the occlusion of a marker is one of the major challenges. The detection algorithm differentiates among types of occlusions and predicts any missing marker position where necessary. As this design is intended to be mounted on a moving carrier, such as a drone or car, a method for compensating the camera’s ego-motion is proposed. The proposed 3D positioning and tracking system is tested in different situations to validate its applicability as a stereo camera rig as well as its performance for motion capture. The performance of the proposed system is compared with that of a standard motion capture system called Vicon and is shown to have the same order of accuracy while incurring less cost

Blind camcording-resistant video watermarking in the DTCWT and SVD domain

Video watermarking techniques can be used to prevent unauthorized users from illegally distributing videos across (social) media networks. However, current watermarking solutions are unable to embed a perceptually invisible watermark which is robust to the distortions introduced by camcording. These watermark-disrupting distortions include lossy compression, the addition of noise, frame-rate conversion and geometric distortions. In this paper, we present a novel video watermarking technique that is blind and robust to camcording attacks. The proposed approach uses the integration of the dual-tree complex wavelet transform (DTCWT) and singular value decomposition (SVD) to achieve robustness against geometric attacks. The experimental results validate our technique's superior imperceptibility and robustness to several attacks when compared to existing peer mechanisms. In conclusion, the proposed technique can be used to protect against illegal distribution of video content

Rate-distortion-preserving forensic watermarking using quantization parameter variation

Watermarking enables the identification of digital pirates that illegally redistribute copyright-protected videos. One of the main challenges is for the watermark to be imperceptible, while not increasing the video bit rate. Additionally, the system should be robust to attacks that attempt to remove the watermark. Therefore, this paper proposes a robust watermarking technique that does not degrade the video quality nor negatively affect the video bit rate. In other words, it preserves the video encoder & x2019;s compression efficiency or rate-distortion performance. For watermark embedding, the quantization parameters are varied during video compression. As a result, different compression artifacts are introduced, although they do not distort the video more than those that occur during ordinary video compression. The collection of artifacts represents the watermark and is used for watermark detection. The experimental results prove that the proposed approach retains the rate-distortion performance better than state-of-the-art techniques. Furthermore, the watermarks are robust to recompression and noise attacks. In conclusion, the proposed method enables content providers to perform forensic watermarking without affecting the compression efficiency