Documents disponibles écrits par cet auteur

Motion-compensated DCT temporal filters for efficient spatio-temporal scalable video coding / Randa Atta in Signal processing. Image communication, Vol. 24 N° 9 (Octobre 2009) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 24 N° 9 (Octobre 2009) . - pp. 702-717 Titre : Motion-compensated DCT temporal filters for efficient spatio-temporal scalable video coding Type de document : texte imprimé Auteurs : Randa Atta, Auteur ; Rawya Rizk, Auteur ; Mohammad Ghanbari, Auteur Article en page(s) : pp. 702-717 Note générale : Electronique Langues : Anglais (eng) Mots-clés : H.264/AVC  Motion-compensation  Lifting  Temporal  discrete  wavelet  transform  DCT  Scalable  video  coding Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Although most of the proposals for implementing motion-compensated temporal filtering (MCTF) schemes are based on the wavelet transform, in this paper, we propose an MCTF framework based on the discrete cosine transform (DCT). Using DCT decimation and interpolation, several temporal decomposition structures named motion-compensated DCT temporal filters (MCDCT-TF) are introduced. These structures are able to employ filters of any length with particular emphasis on 5/3 DCT and 7/4 DCT. The proposed MCDCT-TF and the two-dimensional (2D) DCT decimation technique are incorporated into H.264/AVC to provide spatio-temporal scalability. Compared with the current MCTF-based lifting schemes such as Haar, and 5/3 wavelet filters, simulation results show that the proposed MCDCT-TF utilizing longer tap DCT filters achieves a significant improvement in coding gain. The impact of odd/even group of frames, the decimation/interpolation ratios, and motion-compensated connectivity on the MCDCT-TF performance are also analyzed. Moreover, simulation results show that the performance of the presented scalable video coding is close to the single layer H.264/AVC and is slightly inferior to the temporal scalability supported in JSVM, the state-of-the-art scalable video coding standard, that gets its gain from Hierarchical B-pictures. However, our spatio-temporal coding scheme outperforms the spatio-temporal supported in JSVM even if it uses hierarchical B-pictures to improve its gain. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...] [article] Motion-compensated DCT temporal filters for efficient spatio-temporal scalable video coding [texte imprimé] / Randa Atta, Auteur ; Rawya Rizk, Auteur ; Mohammad Ghanbari, Auteur . - pp. 702-717. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 24 N° 9 (Octobre 2009) . - pp. 702-717 Mots-clés : H.264/AVC  Motion-compensation  Lifting  Temporal  discrete  wavelet  transform  DCT  Scalable  video  coding Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : Although most of the proposals for implementing motion-compensated temporal filtering (MCTF) schemes are based on the wavelet transform, in this paper, we propose an MCTF framework based on the discrete cosine transform (DCT). Using DCT decimation and interpolation, several temporal decomposition structures named motion-compensated DCT temporal filters (MCDCT-TF) are introduced. These structures are able to employ filters of any length with particular emphasis on 5/3 DCT and 7/4 DCT. The proposed MCDCT-TF and the two-dimensional (2D) DCT decimation technique are incorporated into H.264/AVC to provide spatio-temporal scalability. Compared with the current MCTF-based lifting schemes such as Haar, and 5/3 wavelet filters, simulation results show that the proposed MCDCT-TF utilizing longer tap DCT filters achieves a significant improvement in coding gain. The impact of odd/even group of frames, the decimation/interpolation ratios, and motion-compensated connectivity on the MCDCT-TF performance are also analyzed. Moreover, simulation results show that the performance of the presented scalable video coding is close to the single layer H.264/AVC and is slightly inferior to the temporal scalability supported in JSVM, the state-of-the-art scalable video coding standard, that gets its gain from Hierarchical B-pictures. However, our spatio-temporal coding scheme outperforms the spatio-temporal supported in JSVM even if it uses hierarchical B-pictures to improve its gain. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235640%23 [...]

Rate-distortion optimization of scalable video codecs / Hoda Roodaki in Signal processing. Image communication, Vol. 25 N° 4 (Avril 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 4 (Avril 2010) . - pp. 276–286 Titre : Rate-distortion optimization of scalable video codecs Type de document : texte imprimé Auteurs : Hoda Roodaki, Auteur ; Tonko Ćurko, Auteur ; Mohammad Ghanbari, Auteur Année de publication : 2012 Article en page(s) : pp. 276–286 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Rate-distortion  optimization  Scalable  video  coding Résumé : In this paper joint optimization of layers in the layered video coding is investigated. Through theoretical analysis and simulations, it is shown that, due to higher interactions between the layers in a SNR scalable codec, this type of layering technique benefits most from joint optimization of the layers. A method for joint optimization is then proposed, and its compression efficiency is contrasted against the separate optimization and an optimized single layer coder. It is shown that, in joint optimization of SNR scalable coders when the quantization step size of the enhancement layer is larger than half the step size of the base layer, an additional improvement is gained by not sending the enhancement zero valued quantized coefficients, provided they are quantized at the base-layer. This will result in a non-standard bitstream syntax and as an alternative for standard syntax, one may skip the inter coded enhancement macroblocks. Through extensive tests it is shown that while separate optimization of SNR coders is inferior to single layer coder by more than 2 dB, with joint optimization this gap is reduced to 0.3–0.5 dB. We have shown that through joint optimization quality of the base layer video is also improved over the separate optimization. It is also shown that spatial scalability like SNR scalability does benefit from joint optimization, though not being able to exploit the relation between the quantizer step sizes. The amount of improvement depends on the interpolation artifacts of upsampled base-layer and the residual quantization distortion of this layer. Hence, the degree of improvement depends on image contents as well as the bit rate budget. Simulation results show that joint optimization of spatial scalable coders is about 0.5–1 dB inferior to the single layer optimized coder, where its separate optimization counterpart like SNR scalability is more than 2 dB worse. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000056 [article] Rate-distortion optimization of scalable video codecs [texte imprimé] / Hoda Roodaki, Auteur ; Tonko Ćurko, Auteur ; Mohammad Ghanbari, Auteur . - 2012 . - pp. 276–286. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 4 (Avril 2010) . - pp. 276–286 Mots-clés : Rate-distortion  optimization  Scalable  video  coding Résumé : In this paper joint optimization of layers in the layered video coding is investigated. Through theoretical analysis and simulations, it is shown that, due to higher interactions between the layers in a SNR scalable codec, this type of layering technique benefits most from joint optimization of the layers. A method for joint optimization is then proposed, and its compression efficiency is contrasted against the separate optimization and an optimized single layer coder. It is shown that, in joint optimization of SNR scalable coders when the quantization step size of the enhancement layer is larger than half the step size of the base layer, an additional improvement is gained by not sending the enhancement zero valued quantized coefficients, provided they are quantized at the base-layer. This will result in a non-standard bitstream syntax and as an alternative for standard syntax, one may skip the inter coded enhancement macroblocks. Through extensive tests it is shown that while separate optimization of SNR coders is inferior to single layer coder by more than 2 dB, with joint optimization this gap is reduced to 0.3–0.5 dB. We have shown that through joint optimization quality of the base layer video is also improved over the separate optimization. It is also shown that spatial scalability like SNR scalability does benefit from joint optimization, though not being able to exploit the relation between the quantizer step sizes. The amount of improvement depends on the interpolation artifacts of upsampled base-layer and the residual quantization distortion of this layer. Hence, the degree of improvement depends on image contents as well as the bit rate budget. Simulation results show that joint optimization of spatial scalable coders is about 0.5–1 dB inferior to the single layer optimized coder, where its separate optimization counterpart like SNR scalability is more than 2 dB worse. ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596510000056

The impact of tree structures on the performance of zerotree-based wavelet video codecs / Athar Ali Moinuddin in Signal processing. Image communication, Vol. 25 N° 3 (02 ex.) (Mars 2010) 

Public ISBD [article]  in Signal processing. Image communication > Vol. 25 N° 3 (02 ex.) (Mars 2010) . - pp. 179–195 Titre : The impact of tree structures on the performance of zerotree-based wavelet video codecs Type de document : texte imprimé Auteurs : Athar Ali Moinuddin, Auteur ; Ekram Khan, Auteur ; Mohammad Ghanbari, Auteur Année de publication : 2010 Article en page(s) : pp. 179–195 Note générale : Electronique Langues : Anglais (eng) Mots-clés : Zerotree  coding  SPIHT  Color  image  coding  Wavelet  video  Tree  structure Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : In this paper we analyze the impact of tree structures on the performance of zerotree-based wavelet video codecs. Since zerotree approach is based on aggregation of insignificant coefficients in trees, therefore design of a tree structure is the key issue for a better performance. We have considered six different tree structures with characteristics varying from a simple to relatively complex and composite tree structures to code the luminance–chrominance components of a video sequence. Their performances are compared in terms of average number of bits generated per bitplane, number of coded bitplanes for a given bit budget, rate-distortion performance, memory requirements and computational complexity. We observe that in general more complex and longer trees do not necessarily improve the coding efficiency. However, the tree structures encapsulating more elements per tree are memory efficient. Therefore, the rate-distortion performance, memory requirements and computational complexities need to be traded-off while selecting a particular tree structure. It is also observed that the additional improvement due to optional entropy coding is also tree structure dependent. Further, the simulation results show that by designing an efficient tree structure, depending on the picture content, the performance of a video coder can be improved by up to 2.0 dB, while reducing the computational complexity by 45–60% as well as the memory requirements by almost 29–35%. Compared to the standard JPEG2000 (for intra-frame), tree-based coders are found to be efficient in terms of coding and complexity, particularly at lower bit rates. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596509001398 [article] The impact of tree structures on the performance of zerotree-based wavelet video codecs [texte imprimé] / Athar Ali Moinuddin, Auteur ; Ekram Khan, Auteur ; Mohammad Ghanbari, Auteur . - 2010 . - pp. 179–195. Electronique Langues : Anglais (eng) in Signal processing. Image communication > Vol. 25 N° 3 (02 ex.) (Mars 2010) . - pp. 179–195 Mots-clés : Zerotree  coding  SPIHT  Color  image  coding  Wavelet  video  Tree  structure Index. décimale : 621.382 Dispositifs électroniques utilisant les effets des corps solides. Dispositifs semi-conducteurs Résumé : In this paper we analyze the impact of tree structures on the performance of zerotree-based wavelet video codecs. Since zerotree approach is based on aggregation of insignificant coefficients in trees, therefore design of a tree structure is the key issue for a better performance. We have considered six different tree structures with characteristics varying from a simple to relatively complex and composite tree structures to code the luminance–chrominance components of a video sequence. Their performances are compared in terms of average number of bits generated per bitplane, number of coded bitplanes for a given bit budget, rate-distortion performance, memory requirements and computational complexity. We observe that in general more complex and longer trees do not necessarily improve the coding efficiency. However, the tree structures encapsulating more elements per tree are memory efficient. Therefore, the rate-distortion performance, memory requirements and computational complexities need to be traded-off while selecting a particular tree structure. It is also observed that the additional improvement due to optional entropy coding is also tree structure dependent. Further, the simulation results show that by designing an efficient tree structure, depending on the picture content, the performance of a video coder can be improved by up to 2.0 dB, while reducing the computational complexity by 45–60% as well as the memory requirements by almost 29–35%. Compared to the standard JPEG2000 (for intra-frame), tree-based coders are found to be efficient in terms of coding and complexity, particularly at lower bit rates. DEWEY : 361.382 ISSN : 0923-5965 En ligne : http://www.sciencedirect.com/science/article/pii/S0923596509001398