The protection of digital images and video from unauthorized access is important for a number of applications, including privacy protection in video surveillance and digital rights management for consumer applications. However, traditional cryptographic methods are not well suited to digital visual content. Applying standard encryption approaches to the entire content can require significant computational resources due to the large size of the data. Furthermore, digital images and video often need to be manipulated,such as by resizing or transcoding, which traditional encryption would hinder. A number of image and video-specific encryption approaches have been proposed in the literature, but many of the them have significant negative impact on the ability to compress the data, which is a necessary requirement of most imaging systems. In this work, a secure image coder, called Secure Set Partitioning in Hierarchical Trees (SecSPIHT), is proposed. It combines wavelet-based image coding (compression) with efficient encryption. The encryption is applied to a small number of selected bits in the code domain, to achieve complete confidentiality of all the content while having no negative impact on compression performance. The output of the system is a secure code that cannot be decrypted and decoded without the provision of a secret key. It has superior rate-distortion performance compared to JPEG and JPEG2000, and the bit-rate can be easily scaled via a simple truncation operation. The computational overhead of the encryption operation is very low, typically requiring less than 1% of the coded image data to be encrypted. A related secure object-based coding approach is also presented. Called Secure Shape and Texture Set Partitioning in Hierarchical Trees (SecST-SPIHT), it codes and encrypts arbitrarily-shaped visual objects. A privacy protection system for video surveillance is proposed, using SecST-SPIHT to protect private data, such as face and body images appearing in surveillance footage. During normal operation of the system, the private data objects are protected via SecST-SPIHT. If an incident occurs that requires access to the data (e.g., for investigation), a designated authority must release the key. This is superior to other methods of privacy protection which irreversibly blur or mask the private data.

The protection of digital images and video from unauthorized access is important for a number of applications, including privacy protection in video surveillance and digital rights management for consumer applications. However, traditional cryptographic methods are not well suited to digital visual content. Applying standard encryption approaches to the entire content can require significant computational resources due to the large size of the data. Furthermore, digital images and video often need to be manipulated,such as by resizing or transcoding, which traditional encryption would hinder. A number of image and video-specific encryption approaches have been proposed in the literature, but many of the them have significant negative impact on the ability to compress the data, which is a necessary requirement of most imaging systems. In this work, a secure image coder, called Secure Set Partitioning in Hierarchical Trees (SecSPIHT), is proposed. It combines wavelet-based image coding (compression) with efficient encryption. The encryption is applied to a small number of selected bits in the code domain, to achieve complete confidentiality of all the content while having no negative impact on compression performance. The output of the system is a secure code that cannot be decrypted and decoded without the provision of a secret key. It has superior rate-distortion performance compared to JPEG and JPEG2000, and the bit-rate can be easily scaled via a simple truncation operation. The computational overhead of the encryption operation is very low, typically requiring less than 1% of the coded image data to be encrypted. A related secure object-based coding approach is also presented. Called Secure Shape and Texture Set Partitioning in Hierarchical Trees (SecST-SPIHT), it codes and encrypts arbitrarily-shaped visual objects. A privacy protection system for video surveillance is proposed, using SecST-SPIHT to protect private data, such as face and body images appearing in surveillance footage. During normal operation of the system, the private data objects are protected via SecST-SPIHT. If an incident occurs that requires access to the data (e.g., for investigation), a designated authority must release the key. This is superior to other methods of privacy protection which irreversibly blur or mask the private data.

Please read the abstract in the section 00front of this document Copyright 1990, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Barnard, G 1990, High quality coding and reconstruction for transmission of single video images, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-10312007-110001/ > / Dissertation (M Eng (Electronic Engineering))--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / unrestricted

ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper describes a psychophysical experiment to measure visibility thresholds (VT) for quantization distortion in JPEG2000 and an associated quantization algorithm for visually lossless coding of color aerial images. The visibility thresholds are obtained from a quantization distortion model based on the statistical characteristics of wavelet coefficients and the deadzone quantizer of JPEG2000, and the resulting visibility thresholds are presented for the luminance component (Y) and two chrominance components (Cb and Cr). Using the thresholds, we have achieved visually lossless coding for 24-bit color aerial images at an average bitrate of 4.17 bits/pixels, which is approximately 30% of the bitrate required for numerically lossless coding.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / In this work, a scalable perceptual JPEG2000 encoder that exploits properties of the human visual system (HVS) is presented. The algorithm modifies the final three stages of a conventional JPEG2000 encoder. In the first stage, the quantization step size for each subband is chosen to be the inverse of the contrast sensitivity function (CSF). In bit-plane coding, two masking effects are considered during distortion calculation. In the final bitstream formation step, quality layers are formed corresponding to desired perceptual distortion thresholds. This modified encoder exhibits superior visual performance for remote sensing images compared to conventional JPEG2000 encoders. Additionally, it is completely JPEG2000 Part-1 compliant, and therefore can be decoded by any JPEG2000 decoder.

The coding and transmission of the massive datasets captured by Earth Observation (EO) satellites is a critical issue in current missions. The conventional approach is to use compression on board the satellite to reduce the size of the captured images. This strategy exploits spatial and/or spectral redundancy to achieve compression. Another type of redundancy found in such data is the temporal redundancy between images of the same area that are captured at different instants of time. This type of redundancy is commonly not exploited because the required data and computing power are not available on board the satellite. This paper introduces a coding scheme for EO satellites able to exploit this redundancy. Contrary to traditional approaches, the proposed scheme employs both the downlink and the uplink of the satellite. Its main insight is to compute and code the temporal redundancy on the ground and transmit it to the satellite via the uplink. The satellite then uses this information to compress more efficiently the captured image. Experimental results for Landsat 8 images indicate that the proposed dual link image coding scheme can achieve higher coding performance than traditional systems for both lossless and lossy regimes.

JPEG2000 is a recently standardized image compression system that provides substantial improvements over the existing JPEG compression scheme. This improvement in performance comes with an associated cost in increased implementation complexity, such that a purely software implementation is inefficient. This work identifies the arithmetic coder as a bottleneck in efficient hardware implementations, and explores various design options to improve arithmetic coder speed and size. The designs produced improve the critical path of the existing arithmetic coder designs, and then extend the coder throughput to 2 or more symbols per clock cycle. Subsequent work examines more system level implementation issues. This work examines the communication between hardware blocks and utilizes certain modes of operation to add flexibility to buffering solutions. It becomes possible to significantly reduce the amount of intermediate buffering between blocks, whilst maintaining a loose synchronization. Full hardware implementations of the standard are necessarily limited in the amount of features that they can offer, in order to constrain complexity and cost. To circumvent this, a hardware / software codesign is produced using the Altera NIOS II softcore processor. By keeping the majority of the standard implemented in software and using hardware to accelerate those time consuming functions, generality of implementation can be retained, whilst implementation speed is improved. In addition to this, there is the opportunity to explore parallelism, by providing multiple identical hardware blocks to code multiple data units simultaneously.

The Key algorithms of JPEG2000, the new image compression standard, have high computational complexity and thus present challenges for efficient implementation. This has led to research on the hardware optimization of JPEG2000 for its efficient realization. Luckily, in the last century the growth in Microelectronics allows us to realize dedicated ASIC solutions as well as hardware/software FPGA based solutions for complex algorithms such as JPEG2000. But an efficient implementation within hard constraints of area and throughput, demands investigations of key dependencies within the JPEG2000 system. This work presents algorithms and VLSI architectures to realize a high performance JPEG2000 compression system. The embedded block coding algorithm which lies at the heart of a JPEG2000 compression system is a main contributor to enhanced JPEG2000 complexity. This work first concentrates on algorithms to realize low-cost high throughput Block Coder (BC) system. For this purpose concurrent symbol processing capable Bit Plane Coder architecture is presented. Further optimal 2 sub-bank memory and an efficient buffer architectures are designed to keep the hardware cost low. The proposed overall BC system presents the highest Figure Of Merit (FOM) in terms of throughput versus hardware cost in comparison to existing BC solutions. Further, this work also investigates the challenges involved in the efficient integration of the BC with the overall JPEG2000 system. A novel low-cost distortion estimation approach with near-optimal performance is proposed which is necessary for accurate rate-control performance of JPEG2000. Additionally low bandwidth data storage and transfer techniques are proposed for efficient transfer of subband samples to the BC. Simulation results show that the proposed techniques have approximately 4 times less bandwidth than existing architectures. In addition, an efficient high throughput block decoder architecture based on the proposed selective sample-skipping algorithm is presented. The proposed architectures are designed and analyzed on both ASIC and FPGA platforms. Thus, the proposed algorithms, architectures and efficient BC integration strategies are useful for realizing a dedicated ASIC JPEG2000 system as well as a hardware/software FPGA based JPEG2000 solution. Overall this work presents algorithms and architectures to realize a high performance JPEG2000 system without imposing any restrictions in terms of coding modes or block size for the BC system.

<p>In ordinary image coding, the same image quality is obtained in all parts of an image. If it is known that there is only one viewer, and where in the image that viewer is focusing, the quality can be degraded in other parts of the image without incurring any perceptible coding artefacts. This master's thesispresents a coding scheme where an image is segmented into homogeneous regions which are then separately coded, and where knowledge about the user's focus point is used to obtain further data reduction. It is concluded that the coding performance does not quite reach the levels attained when applying focus-based quality degradation to coding schemes not based on segmentation.</p>

<p>In today's video delivery and broadcast networks, issues of copyright protection have become more urgent than in analog times, since the copying of digital video does not result in the decrease in quality that occurs when analog video is copied. </p><p>One method of copyright protection is to embed a digital code, a"watermark", into the video sequence. The watermark can then unambiguously identify the copyright holder of the video sequence. Watermarks can also be used to identify the purchaser of a video sequence, which is called "fingerprinting". </p><p>The objective of this master thesis was to implement a program that would insert watermarks into video sequences and also detect if a given video sequence contains a givenwatermark. </p><p>The video standard I chose to use was the H.264 standard (also known as MPEG4 AVC) as it offers a significant efficiency improvement over the previous video compression standards. </p><p>A couple of tests that can be considered representative for most image manipulations and attacks were performed. The program passed all tests, suggesting that the watermarking mechanism of this thesis can be expected to be rather robust, at least for the video sequence used. By looking at the watermarked video sequences and comparing them to the originals, or measuring the signal to noise ratio, one can also see that the watermarks are unobtrusive. The execution times were also measured. Compared to coding and decoding a H.264 video stream, the time it takes to insert and extract watermarks was much less. Calculating a threshold takes roughly double the time as decoding the sequence, though.</p>