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Most of all data-reduced HD-VCRs use powerful error protection schemes in order to prevent error propagation. Under normal conditions these schemes are able to correct all errors from the magnetic tape channel. However, under bad conditions some uncorrected errors may be left. Therefore, it must be possible to conceal erroneous DCT blocks in order to avoid visible degradations in this worst-case situation. In this context four different concealment techniques (spatial, temporal, motion-adaptive and motion-compensated concealment) are discussed and compared with respect to their efficiency. The results of subjective tests and the discussion of some system aspects show that the motion-adaptive approach is the most suitable one for the underlying application.

Three-dimensional displays provide an unambiguous visual representation of the spatial structure of natural scenes and computer-generated virtual environments and thus have proven substantial advantages over conventional displays in remote guidance and inspection tasks and in application fields such as medical imagery and architectural and molecular modelling. Recent years have seen increasing efforts to extend 3D technologies into the domain of image communications. These efforts received support from human factors studies indicating that 3D displays are highly appreciated by prospective users of image communications systems for their enhanced psychological effects (telepresence and communicative presence). On the other hand, these studies have revealed heavy technological requirements that must be met in order to avoid visible image distortions and increased visual strain.

Most international standards recommend the use of reference monitors in subjective testing for visual quality. But do we really need to use reference monitors? In order to find an answer to this question, we conducted extensive subjective tests with reference, color calibrated high quality and uncalibrated standard monitors. We not only used different HDTV sequences, but also two fundamentally different encoders: AVC/H.264 and Dirac. Our results show that using the uncalibrated standard monitor, the test subjects underestimate the visual quality compared to the reference monitor. Between the reference and a less expensive color calibrated high quality monitor, however, we were unable to find a statistically significant difference in most cases. This might be an indication that both can be used equivalently in subjective testing, although further studies will be necessary in order to get a definitive answer.

A two-stage coding system for reducing the usually high data rate of an HDTV signal to less than 140 Mbit/s is herein described. Three-dimensional subsampling is used to reduce the number of samples of the digitized interlaced source signal. A motion-adaptive filter structure adjusts the three-dimensional spectrum of the television signal to some reduced region which is supported by the quincunx sampling pattern. The visibility of the transition between different spatial resolutions is decreased by 3D-filtering of slowly moving areas. As a result of subsampling, the sampling frequency is halved. Transform coding of the remaining samples is then performed. The quincunx sampling structure is rotated within blocks of 8 by 8 to result in a rectangular block structure. Different possibilities for transforming the quincunx sampled field have been investigated and compared in terms of energy concentration, entropy calculation and coding efficiency. A data reduction of the transform coefficients is sought in the range of four and five. A modified threshold coding algorithm is used to code the coefficients. Sampling, normalization and quantization are adapted and controlled by the buffer status. The buffer equalizes the variable bit-rate at the output of the variable length coder. All steps of signal processing have to be adapted to preserve the high quality of the original signal.

The introduction of Microsoft's new graphics file format, Windows Media Photo, into the mainstream market in 2006 has been one of the most interesting developments in the digital world. The file format, which has since been renamed to HD Photo in November of 2006, is being touted as the successor to the ubiquitous JPEG image format, as well as the eventual de facto standard in the digital photography market. With massive efforts already underway to increase the software support of this file format, to make available support for digital camera makers to incorporate it into their products, and to propose the file format to the Joint Photography Experts Group in order to make HD Photo as a standard itself, HD Photo is poised to become as widespread as any of the common image file formats today. This provides the motivation into studying whether the HD Photo file format can be used as a vehicle to compromise a user s system. This work addresses the security of handling the HD Photo file format as it pertains to image viewer applications. Whenever an application is updated to accommodate a new file format, it is possible that the application in question can be vulnerable to exploitation. This is a concern, especially if a malformed instance of that file format can make the application to deviate from its specified behavior and cause the execution of arbitrary code. This thesis investigates if some of the existing applications today that render image files are susceptible to compromise by opening a malformed HD Photo image file. The goal of this thesis is to test the security of various image viewer applications compatible with the HD Photo file format. We modified MiniFuzz, an automated fuzzing tool, to conduct mutation-based smart fuzzing and generation-based fuzzing. The test instrumentation worked correctly, but the test cases did not reveal any security vulnerabilities. http://archive.org/details/vulnerabilitynal109453285 Funded By: CNS-0430566 Naval Postgraduate School author (civilian). Approved for public release; distribution is unlimited.

The realization of a TV-interlaced (TVI) to HDTV-interlaced (HDI) real-time format converter for studio applications is described. The conversion is performed by motion-compensated 3-D interpolation. The estimation of motion is based on hiera rchical block matching. Reliability checking of motion vectors is applied to achieve high picture quality. Furthermore, various picture classification algorithms are utilized to improve the reliability of motion vectors. This format converter has been developed using specially designed VLSI chips, digital signal processors, and field-programmable gate arrays for the reduction of hardware. The special VLSI chips have been developed using semicustom and fuli-custom design techniques. Besides employment within the format converter they are suitable for various applications in video processing.

A constant-luminance-coding (CIELAB) codec is presented for high-definition TV (HDTV) use that offers the possibility of enlarging the reproducible color TV spectrum by selecting a new set of primary colors. Tests on a BBC standard color card showed that this type of processing gives full flexibility for the choice of receiver and camera primaries and transparency for the transmission of all real surface colors. Subjective tests were carried out to investigate the importance of a wider color spectrum and the acceptability of CIELAB coding in a compatible HD-MAC system. It was found that more saturated primaries help to minimize calorimetric distortions if CIELAB coded signals are decoded by a conventional decoder. >