It is well known that tile-boundary artifacts occur in wavelet-based lossy image coding. However,... more It is well known that tile-boundary artifacts occur in wavelet-based lossy image coding. However, until now, their cause has not been understood well. In this paper, we show that boundary artifacts are an inescapable consequence of the usual methods used to choose tile size and the type of symmetric extension employed in a wavelet-based image decomposition system. This paper presents a novel method for reducing these tile-boundary artifacts. The method employs odd tile sizes (2 + 1 samples) rather than the conventional even tile sizes (2 samples). It is shown that, for the same bit rate, an image compressed using an odd tile length low-pass first (OTLPF) convention has significantly less boundary artifacts than an image compressed using even tile sizes. The OTLPF convention can also be incorporated into the JPEG 2000 image compression algorithm using extensions defined in Part 2 of this standard.
IEEE Transactions on Circuits and Systems for Video Technology, 2005
In many scenarios where it is desirable to provide a number of different descriptions of a video ... more In many scenarios where it is desirable to provide a number of different descriptions of a video sequence, the simulcasting of single-layer bitstreams is impractical due to the amount of data involved. The new technique "stream morphing" introduced in this paper exploits the redundancy that exists between different compressed descriptions of the same video sequence at different quality levels. This works to dramatically reduce the data rates required to achieve the same effect as simulcast. The results shown here indicate that an SNR scalable video system constructed using this principle outperforms the structures defined in MPEG-2 and the MPEG-4 Streaming Video Profile. Stream morphing has a number of additional advantages: no loss of subjective quality compared to single-layer bitstreams at the same peak SNR regardless of the number of layers involved (unlike the MPEG-2 approach), the ability to generate a scalable representation of a video sequence from a set of single-layer descriptions in a computationally inexpensive way, and compatibility with existing single-layer decoders via a simple preprocessor without the need for transcoding. Stream morphing is demonstrated here in the context of MPEG-4; however, it is compatible with other similar video coding standards.
Proceedings / ICIP ... International Conference on Image Processing
Stream morphing has been previously introduced as an efficient way of simulcasting a hierarchy of... more Stream morphing has been previously introduced as an efficient way of simulcasting a hierarchy of single-layer descriptions of a single video sequence with different levels of quality while sharing the same frame size and rate. One application for this process was SNR scalable video coding. This paper presents two different adaptations of the stream morphing process to temporal scalability, one with bi-directional motion-compensated prediction and one without. Both methods retain the attractive features of the original SNR scalable structure, notably the use of a single quantization cycle and single decoder motion-compensated prediction loop irrespective of the number of layers present and the ability to convert between single-layer and scalable forms without transcoding.
During Stereoscopic 3D (S3D) video transmission, one or both views can be affected by bit errors ... more During Stereoscopic 3D (S3D) video transmission, one or both views can be affected by bit errors and packet losses caused by adverse channel conditions, delay or jitter. Typically, the Human Visual System (HVS) is incapable of aligning and fusing stereoscopic content if one view is affected by artefacts caused by compression, transmission and rendering with distorted patterns being perceived as alterations of the original which presents a shimmering effect known as binocular rivalry and is detrimental to a user's Quality of Experience (QoE). This study attempts to quantify the effects of binocular rivalry for stereoscopic videos. Existing approaches, in which one or more frames are lost in one or both views undergo error concealment, are implemented. Then, subjective testing is carried out on the error concealed 3D video sequences. The evaluations provided by these subjects were then combined and analysed using a standard Student t-test thus quantifying the impact of binocular r...
Over the last decade, different technologies to visualize 3D scenes have been introduced and impr... more Over the last decade, different technologies to visualize 3D scenes have been introduced and improved. These technologies include stereoscopic, multi-view, integral imaging and holographic types. Despite increasing consumer interest; poor image quality, crosstalk or side effects of 3D displays and also the lack of defined broadcast standards has hampered the advancement of 3D displays to the mass consumer market. Also, in real time transmission of 3DTV sequences over packet-based networks may results in visual quality degradations due to packet loss and others. In the conventional 2D videos different extrapolation and directional interpolation strategies have been used for concealing the missing blocks but in 3D, it is still an emerging field of research. Few studies have been carried out to define the assessment methods of stereoscopic images and videos. But through industrial and commercial perspective, subjective quality evaluation is the most direct way to evaluate human percept...
IEE Proceedings F Communications, Radar and Signal Processing
Constant-area quantisation (CAQ), a predictive encoding scheme specifically designed for the tran... more Constant-area quantisation (CAQ), a predictive encoding scheme specifically designed for the transmission of images over narrowband channels, is discussed, and modifications to both the predictor and quantiser are described. These modifications result in improved image quality at a lower transmitted bit rate while still maintaining the relative simplicity of hardware implementation of the CAQ encoder. It is shown that transmission errors can lead to severe degradation of the received images in CAQ-based communications systems, resulting in both loss of line synchronism and random shifts in grey level. Solutions to both of these problems are given allowing usable reconstructed images to be obtained at bit error rates in excess of 10" 3 .
International Conference on Image Processing, 2000
Multiple Description Coding (MDC) of video is a useful technique for robust video transmission ov... more Multiple Description Coding (MDC) of video is a useful technique for robust video transmission over unreliable networks. MDC not only provides at least acceptable quality of video in error-prone network but it also efficiently utilizes the multipath nature of internet and wireless networks. In this paper, multiple description video coding with 3-D Set Partitioning in Hierarchical Tree (3D-SPIHT) codec has
We investigate streaming MPEG-4 video over relative Differentiated Services (DS) networks that ca... more We investigate streaming MPEG-4 video over relative Differentiated Services (DS) networks that can provide Q aggregated classes ordered in a way such that class q is better or at least no worse than class (q-1) for 1 qQ <≤ , in terms of packet loss. We propose an algorithm to measure the loss impact of a video packet on the
TENCON '97 Brisbane - Australia. Proceedings of IEEE TENCON '97. IEEE Region 10 Annual Conference. Speech and Image Technologies for Computing and Telecommunications (Cat. No.97CH36162), 1997
Page 1. VIDEO ERROR CONCEALMENT USING DECODER MOTION VECTOR ESTIMATION ... Abstract Audio-visual ... more Page 1. VIDEO ERROR CONCEALMENT USING DECODER MOTION VECTOR ESTIMATION ... Abstract Audio-visual and other multimedia services are seen as important sources of traffic for future wireless networks. ...
Proceedings 1998 International Conference on Image Processing. ICIP98 (Cat. No.98CB36269), 1998
When errors are introduced into a compressed video bit-stream, blocks of pixels are lost. The dec... more When errors are introduced into a compressed video bit-stream, blocks of pixels are lost. The decoder attempts to conceal this loss to maximize the displayed picture quality. Previous approaches use either surrounding pixels in the current picture to conceal lost blocks (spatial concealment) or pixels from the previous picture (temporal concealment). We show how joint spatial temporal concealment can be
2004 International Conference on Image Processing, 2004. ICIP '04., 2004
... Edward H. S. Lot, Mark Pickering, Michael Frater and John Amold ... The first one, in Figure ... more ... Edward H. S. Lot, Mark Pickering, Michael Frater and John Amold ... The first one, in Figure 3 shows a group of zebras against a backdrop of vegetation. Figure 4 shows the second image and contilins a leopard semi-camouflaged within a patch of grass. ...
IEEE International Conference on Image Processing 2005, 2005
ABSTRACT In this paper, we propose a robust approach to super-resolution static sprite generation... more ABSTRACT In this paper, we propose a robust approach to super-resolution static sprite generation from multiple low-resolution images. Considering both short-term and long-term motion influences, a hybrid global motion estimation technique is first presented for sprite generation. An iterative super-resolution reconstruction algorithm is then proposed for the super-resolution sprite construction. This algorithm is robust to outliers and results in a sprite image with high visual quality. In addition, the generated super-resolution sprite can provide better reconstructed images than a conventional low-resolution sprite. Experimental results demonstrate the effectiveness of the proposed methods.
2008 IEEE 10th Workshop on Multimedia Signal Processing, 2008
ABSTRACT The problem of resilient video transmission over lossy packet networks is addressed in t... more ABSTRACT The problem of resilient video transmission over lossy packet networks is addressed in this paper. We propose a rate-distortion optimized multiple description (MD) codec. Two different optimization controls of the codec are described that are suited to rates of packet loss, including the case where packets can travel over multiple paths through the network, with each path-dependent packet-loss probabilities. A packetization method optimized to work seamlessly with the proposed MD codec is also proposed. Simulations performed under various packet loss scenarios show the importance of the two optimizations and also that the proposed framework achieves significantly improved video quality when compared with similar techniques.
Proceedings of 2010 IEEE International Symposium on Circuits and Systems, 2010
This paper introduces a new approach to motion compensated prediction for video compression. A tw... more This paper introduces a new approach to motion compensated prediction for video compression. A two-way motion compensation approach is utilized in which the motion compensated prediction is generated either from a super resolution mosaic accumulated using a number of previously decoded frames or from a low-resolution reference frame. The super resolution mosaic is constructed using our improved global motion estimation
2009 16th IEEE International Conference on Image Processing (ICIP), 2009
In the most common form of wavelet video coding, a three-dimensional discrete wavelet transform (... more In the most common form of wavelet video coding, a three-dimensional discrete wavelet transform (DWT) is applied on a group of video frames (GOF). This approach suffers in compression performance because no motion compensation is used. Other approaches to motion compensated wavelet video coding fails to achieve good video quality in packet loss network due to the absence of a
2008 IEEE 10th Workshop on Multimedia Signal Processing, 2008
Motion estimation and compensation contribute greatly to video compression efficiency. Previous w... more Motion estimation and compensation contribute greatly to video compression efficiency. Previous work has explored the effects of higher-order motion models with standard block sizes on video coding, but the impact on compression efficiency has not been sufficient to see such approaches adopted in mainstream video-compression standards. In this paper, we put forward a new strategy to augment the performance of extended motion models in the perspective of classical block-matching algorithms. To accomplish superior compression, the proposed scheme takes advantage of larger blocks with multi-level partitioning and a higher order elastic motion model. Performance evaluations show that these two features, when combined under a common framework, can significantly outperform the existing techniques including those available in the recent H.264 standard.
It is well known that tile-boundary artifacts occur in wavelet-based lossy image coding. However,... more It is well known that tile-boundary artifacts occur in wavelet-based lossy image coding. However, until now, their cause has not been understood well. In this paper, we show that boundary artifacts are an inescapable consequence of the usual methods used to choose tile size and the type of symmetric extension employed in a wavelet-based image decomposition system. This paper presents a novel method for reducing these tile-boundary artifacts. The method employs odd tile sizes (2 + 1 samples) rather than the conventional even tile sizes (2 samples). It is shown that, for the same bit rate, an image compressed using an odd tile length low-pass first (OTLPF) convention has significantly less boundary artifacts than an image compressed using even tile sizes. The OTLPF convention can also be incorporated into the JPEG 2000 image compression algorithm using extensions defined in Part 2 of this standard.
IEEE Transactions on Circuits and Systems for Video Technology, 2005
In many scenarios where it is desirable to provide a number of different descriptions of a video ... more In many scenarios where it is desirable to provide a number of different descriptions of a video sequence, the simulcasting of single-layer bitstreams is impractical due to the amount of data involved. The new technique "stream morphing" introduced in this paper exploits the redundancy that exists between different compressed descriptions of the same video sequence at different quality levels. This works to dramatically reduce the data rates required to achieve the same effect as simulcast. The results shown here indicate that an SNR scalable video system constructed using this principle outperforms the structures defined in MPEG-2 and the MPEG-4 Streaming Video Profile. Stream morphing has a number of additional advantages: no loss of subjective quality compared to single-layer bitstreams at the same peak SNR regardless of the number of layers involved (unlike the MPEG-2 approach), the ability to generate a scalable representation of a video sequence from a set of single-layer descriptions in a computationally inexpensive way, and compatibility with existing single-layer decoders via a simple preprocessor without the need for transcoding. Stream morphing is demonstrated here in the context of MPEG-4; however, it is compatible with other similar video coding standards.
Proceedings / ICIP ... International Conference on Image Processing
Stream morphing has been previously introduced as an efficient way of simulcasting a hierarchy of... more Stream morphing has been previously introduced as an efficient way of simulcasting a hierarchy of single-layer descriptions of a single video sequence with different levels of quality while sharing the same frame size and rate. One application for this process was SNR scalable video coding. This paper presents two different adaptations of the stream morphing process to temporal scalability, one with bi-directional motion-compensated prediction and one without. Both methods retain the attractive features of the original SNR scalable structure, notably the use of a single quantization cycle and single decoder motion-compensated prediction loop irrespective of the number of layers present and the ability to convert between single-layer and scalable forms without transcoding.
During Stereoscopic 3D (S3D) video transmission, one or both views can be affected by bit errors ... more During Stereoscopic 3D (S3D) video transmission, one or both views can be affected by bit errors and packet losses caused by adverse channel conditions, delay or jitter. Typically, the Human Visual System (HVS) is incapable of aligning and fusing stereoscopic content if one view is affected by artefacts caused by compression, transmission and rendering with distorted patterns being perceived as alterations of the original which presents a shimmering effect known as binocular rivalry and is detrimental to a user's Quality of Experience (QoE). This study attempts to quantify the effects of binocular rivalry for stereoscopic videos. Existing approaches, in which one or more frames are lost in one or both views undergo error concealment, are implemented. Then, subjective testing is carried out on the error concealed 3D video sequences. The evaluations provided by these subjects were then combined and analysed using a standard Student t-test thus quantifying the impact of binocular r...
Over the last decade, different technologies to visualize 3D scenes have been introduced and impr... more Over the last decade, different technologies to visualize 3D scenes have been introduced and improved. These technologies include stereoscopic, multi-view, integral imaging and holographic types. Despite increasing consumer interest; poor image quality, crosstalk or side effects of 3D displays and also the lack of defined broadcast standards has hampered the advancement of 3D displays to the mass consumer market. Also, in real time transmission of 3DTV sequences over packet-based networks may results in visual quality degradations due to packet loss and others. In the conventional 2D videos different extrapolation and directional interpolation strategies have been used for concealing the missing blocks but in 3D, it is still an emerging field of research. Few studies have been carried out to define the assessment methods of stereoscopic images and videos. But through industrial and commercial perspective, subjective quality evaluation is the most direct way to evaluate human percept...
IEE Proceedings F Communications, Radar and Signal Processing
Constant-area quantisation (CAQ), a predictive encoding scheme specifically designed for the tran... more Constant-area quantisation (CAQ), a predictive encoding scheme specifically designed for the transmission of images over narrowband channels, is discussed, and modifications to both the predictor and quantiser are described. These modifications result in improved image quality at a lower transmitted bit rate while still maintaining the relative simplicity of hardware implementation of the CAQ encoder. It is shown that transmission errors can lead to severe degradation of the received images in CAQ-based communications systems, resulting in both loss of line synchronism and random shifts in grey level. Solutions to both of these problems are given allowing usable reconstructed images to be obtained at bit error rates in excess of 10" 3 .
International Conference on Image Processing, 2000
Multiple Description Coding (MDC) of video is a useful technique for robust video transmission ov... more Multiple Description Coding (MDC) of video is a useful technique for robust video transmission over unreliable networks. MDC not only provides at least acceptable quality of video in error-prone network but it also efficiently utilizes the multipath nature of internet and wireless networks. In this paper, multiple description video coding with 3-D Set Partitioning in Hierarchical Tree (3D-SPIHT) codec has
We investigate streaming MPEG-4 video over relative Differentiated Services (DS) networks that ca... more We investigate streaming MPEG-4 video over relative Differentiated Services (DS) networks that can provide Q aggregated classes ordered in a way such that class q is better or at least no worse than class (q-1) for 1 qQ <≤ , in terms of packet loss. We propose an algorithm to measure the loss impact of a video packet on the
TENCON '97 Brisbane - Australia. Proceedings of IEEE TENCON '97. IEEE Region 10 Annual Conference. Speech and Image Technologies for Computing and Telecommunications (Cat. No.97CH36162), 1997
Page 1. VIDEO ERROR CONCEALMENT USING DECODER MOTION VECTOR ESTIMATION ... Abstract Audio-visual ... more Page 1. VIDEO ERROR CONCEALMENT USING DECODER MOTION VECTOR ESTIMATION ... Abstract Audio-visual and other multimedia services are seen as important sources of traffic for future wireless networks. ...
Proceedings 1998 International Conference on Image Processing. ICIP98 (Cat. No.98CB36269), 1998
When errors are introduced into a compressed video bit-stream, blocks of pixels are lost. The dec... more When errors are introduced into a compressed video bit-stream, blocks of pixels are lost. The decoder attempts to conceal this loss to maximize the displayed picture quality. Previous approaches use either surrounding pixels in the current picture to conceal lost blocks (spatial concealment) or pixels from the previous picture (temporal concealment). We show how joint spatial temporal concealment can be
2004 International Conference on Image Processing, 2004. ICIP '04., 2004
... Edward H. S. Lot, Mark Pickering, Michael Frater and John Amold ... The first one, in Figure ... more ... Edward H. S. Lot, Mark Pickering, Michael Frater and John Amold ... The first one, in Figure 3 shows a group of zebras against a backdrop of vegetation. Figure 4 shows the second image and contilins a leopard semi-camouflaged within a patch of grass. ...
IEEE International Conference on Image Processing 2005, 2005
ABSTRACT In this paper, we propose a robust approach to super-resolution static sprite generation... more ABSTRACT In this paper, we propose a robust approach to super-resolution static sprite generation from multiple low-resolution images. Considering both short-term and long-term motion influences, a hybrid global motion estimation technique is first presented for sprite generation. An iterative super-resolution reconstruction algorithm is then proposed for the super-resolution sprite construction. This algorithm is robust to outliers and results in a sprite image with high visual quality. In addition, the generated super-resolution sprite can provide better reconstructed images than a conventional low-resolution sprite. Experimental results demonstrate the effectiveness of the proposed methods.
2008 IEEE 10th Workshop on Multimedia Signal Processing, 2008
ABSTRACT The problem of resilient video transmission over lossy packet networks is addressed in t... more ABSTRACT The problem of resilient video transmission over lossy packet networks is addressed in this paper. We propose a rate-distortion optimized multiple description (MD) codec. Two different optimization controls of the codec are described that are suited to rates of packet loss, including the case where packets can travel over multiple paths through the network, with each path-dependent packet-loss probabilities. A packetization method optimized to work seamlessly with the proposed MD codec is also proposed. Simulations performed under various packet loss scenarios show the importance of the two optimizations and also that the proposed framework achieves significantly improved video quality when compared with similar techniques.
Proceedings of 2010 IEEE International Symposium on Circuits and Systems, 2010
This paper introduces a new approach to motion compensated prediction for video compression. A tw... more This paper introduces a new approach to motion compensated prediction for video compression. A two-way motion compensation approach is utilized in which the motion compensated prediction is generated either from a super resolution mosaic accumulated using a number of previously decoded frames or from a low-resolution reference frame. The super resolution mosaic is constructed using our improved global motion estimation
2009 16th IEEE International Conference on Image Processing (ICIP), 2009
In the most common form of wavelet video coding, a three-dimensional discrete wavelet transform (... more In the most common form of wavelet video coding, a three-dimensional discrete wavelet transform (DWT) is applied on a group of video frames (GOF). This approach suffers in compression performance because no motion compensation is used. Other approaches to motion compensated wavelet video coding fails to achieve good video quality in packet loss network due to the absence of a
2008 IEEE 10th Workshop on Multimedia Signal Processing, 2008
Motion estimation and compensation contribute greatly to video compression efficiency. Previous w... more Motion estimation and compensation contribute greatly to video compression efficiency. Previous work has explored the effects of higher-order motion models with standard block sizes on video coding, but the impact on compression efficiency has not been sufficient to see such approaches adopted in mainstream video-compression standards. In this paper, we put forward a new strategy to augment the performance of extended motion models in the perspective of classical block-matching algorithms. To accomplish superior compression, the proposed scheme takes advantage of larger blocks with multi-level partitioning and a higher order elastic motion model. Performance evaluations show that these two features, when combined under a common framework, can significantly outperform the existing techniques including those available in the recent H.264 standard.
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Papers by John Arnold