The Experts below are selected from a list of 50829 Experts worldwide ranked by ideXlab platform

Panos Nasiopoulos - One of the best experts on this subject based on the ideXlab platform.

  • Compression Efficiency of High Dynamic Range and Wide Color Gamut Pixel’s Representation
    IEEE Transactions on Broadcasting, 2018
    Co-Authors: Ronan Boitard, Mahsa T. Pourazad, Panos Nasiopoulos
    Abstract:

    Ultra-high definition (UHD) is currently being deployed in video distribution pipelines for improved quality of experience. This new recommendation not only improves spatial and temporal resolution, but also the quality and accuracy of pixels using wide color gamut (WCG) and high dynamic range (HDR) technologies. Indeed, HDR video technology aims at conveying the full range of perceptible shadow and highlight details with enough different tonal levels to prevent loss of visual information, while WCG increases the amount of visible color that can be represented. However, these technologies require different standard digital pixel representations than the ones currently employed in high definition (HD) television. While the impact of increasing spatial and temporal resolution (i.e., increase of resolution and frame rate) on Compression Efficiency has already been assessed, it is not clear how new pixel representations would affect the Compression performance. In this paper, we discuss the differences between HD color pixel representation and the newly standardized representations developed to meet the requirements introduced by WCG and HDR. Moreover we explain why existing HD pixel representations are sub-efficient for encoding HDR and WCG pixels. We also perform a statistical analysis of pixel distribution in real images to explain how pixel’s representation influences Compression Efficiency. Results show that by tailoring a pixel representation upon the range of luminance and color values accessible in content and displays, bandwidth savings can be achieved while increasing the quality of delivered content. We conclude this paper by discussing the shortcomings of the color pixel representation recommended for the UHD television standards and provide guidelines to create a more efficient one.

  • Perceptual rate distortion optimization of 3D–HEVC using PSNR-HVS
    Multimedia Tools and Applications, 2017
    Co-Authors: Sima Valizadeh, Panos Nasiopoulos, Rabab K. Ward
    Abstract:

    Improved Compression Efficiency is highly desirable in the transmission of 3D video and its storage. 3D–HEVC achieves higher Compression Efficiency compared to the simulcast HEVC or disparity-compensated multi-view video coding (MVC). In 3D–HEVC, the mean square error (MSE) is used to measure distortion in the rate distortion optimization process. However, MSE is not a good measure to use for measuring visual quality, as it poorly correlates with human perception. We propose to integrate a perceptual video quality metric inside the rate distortion optimization process of the 3D–HEVC. Specifically, in the coding unit (CU) mode selection process, PSNR-HVS is used as a measure for distortion. PSNR-HVS is based on the characteristics of the human visual system (HVS). Performance evaluations show that the proposed approach improves the Compression Efficiency of 3D–HEVC for multi-view videos by 2.78%.

  • ICASSP - Optimizing Non Constant Luminance into Constant Luminance for High Dynamic Range Video Distribution
    2017 IEEE International Conference on Acoustics Speech and Signal Processing (ICASSP), 2017
    Co-Authors: Fujun Xie, Ronan Boitard, Mahsa T. Pourazad, Panos Nasiopoulos
    Abstract:

    To improve Compression Efficiency, pixels are traditionally represented using a luma and two chroma values. Such a representation aims at separating light from color information. Two methods are usually considered for computing luma values: Non-Constant Luminance (NCL) and Constant Luminance (CL). CL equations have been derived from the luminous efficacy of the used gamut color primaries in the light linear domain. NCL applies the same equations but on perceptually encoded values, thus resulting in lower Compression Efficiency and hue shifts. However, given the higher hardware complexity for implementing CL, the common operational practice in legacy television distribution is to use NCL. In this paper, our motivation is to derive a new set of equations that provides the Compression benefits of CL with the lower complexity of NCL for High Dynamic Range video distribution. Results show that the proposed method increases Compression Efficiency significantly over the NCL approach while maintaining NCL's cost complexity.

  • high dynamic range versus standard dynamic range Compression Efficiency
    2016 Digital Media Industry & Academic Forum (DMIAF), 2016
    Co-Authors: Ronan Boitard, Mahsa T. Pourazad, Panos Nasiopoulos
    Abstract:

    High Dynamic Range (HDR) image and video technology aims at conveying the full range of perceptible shadow and highlight details with sufficient precision. HDR is regarded by many experts as the next evolution in digital media. However, industrial broadcasters have concerns regarding the bandwidth overhead that this new technology entails. While many consider that broadcasting HDR content would increase bandwidth requirements by around 20%, this number is based on studies where, in addition to the SDR main stream, HDR-related side information is conveyed. A recent subjective evaluation reported that encoding HDR video content in a single layer might require less bandwidth than its associated SDR version. Similar results were discussed in the MPEG ad-hoc group on High Dynamic Range and Wide Color Gamut. In this article, we explain how having more information can result in lower bandwidth requirements. To this end, we describe several limitations of the human vision system that, when exploited, optimize the HDR distribution pipeline for a human observer. Our theoretical assumption about the higher Efficiency of HDR is backed up by a statistical analysis of pixel distribution in real images. The Spatial Index objective metric also reconfirms our assumption.

  • ICCE - Perceptual distortion measurement in the coding unit mode selection for 3D-HEVC
    2016 IEEE International Conference on Consumer Electronics (ICCE), 2016
    Co-Authors: Sima Valizadeh, Panos Nasiopoulos, Rabab K. Ward
    Abstract:

    3D-HEVC achieves higher Compression Efficiency compared with the simulcast HEVC or disparity-compensated multi-view video coding (MVC). Improved Compression Efficiency is highly desirable in the transmission of 3D video and its storage. The coding Efficiency gain is the result of the new coding tools introduced in 3D-HEVC such as inter-view motion prediction and inter-view residual prediction. We propose to integrate a perceptual video quality metric inside the rate distortion optimization process of the 3D-HEVC. Specifically, in the coding unit (CU) mode selection process, PSNR-HVS is used as a measure for distortion. PSNR-HVS is based on the characteristics of the human visual system (HVS). Results show that the proposed approach improves the Compression Efficiency of the 3D-HEVC and achieves higher video quality compared with 3D-HEVC.

Touradj Ebrahimi - One of the best experts on this subject based on the ideXlab platform.

  • comparison of Compression Efficiency between hevc h 265 vp9 and av1 based on subjective quality assessments
    Quality of Multimedia Experience, 2018
    Co-Authors: Pinar Akyazi, Touradj Ebrahimi
    Abstract:

    The growing requirements for broadcasting and streaming of high quality video continue to trigger demands for codecs with higher Compression Efficiency. AV1 is the most recent open and royalty free video coding specification developed by Alliance for Open Media (AOMedia) with a declared ambition of becoming the most popular next generation video coding standard. Primary alternatives to AV1 are the VP9 and the HEVC/H.265 which are currently among the most popular and widespread video codecs used in applications. VP9 is also a royalty free and open specification similar to AV1, while HEVC/H.265 requires specific licensing terms for its use in commercial products and services. In this paper, we compare AV1 to VP9 and HEVC/H.265 from rate distortion point of view in a broadcasting use case scenario. Mutual comparison is performed by means of subjective evaluations carried out in a controlled environment using HD video content with typical bitrates ranging from low to high, corresponding to very low up to completely transparent quality. We then proceed with an in-depth analysis of advantages and drawbacks of each codec for specific types of content and compare the subjective comparisons and conclusions to those obtained by others in the state of the art as well to those measured by means of objective metrics such as PSNR.

  • QoMEX - Comparison of Compression Efficiency between HEVC/H.265, VP9 and AV1 based on Subjective Quality Assessments
    2018 Tenth International Conference on Quality of Multimedia Experience (QoMEX), 2018
    Co-Authors: Pinar Akyazi, Touradj Ebrahimi
    Abstract:

    The growing requirements for broadcasting and streaming of high quality video continue to trigger demands for codecs with higher Compression Efficiency. AV1 is the most recent open and royalty free video coding specification developed by Alliance for Open Media (AOMedia) with a declared ambition of becoming the most popular next generation video coding standard. Primary alternatives to AV1 are the VP9 and the HEVC/H.265 which are currently among the most popular and widespread video codecs used in applications. VP9 is also a royalty free and open specification similar to AV1, while HEVC/H.265 requires specific licensing terms for its use in commercial products and services. In this paper, we compare AV1 to VP9 and HEVC/H.265 from rate distortion point of view in a broadcasting use case scenario. Mutual comparison is performed by means of subjective evaluations carried out in a controlled environment using HD video content with typical bitrates ranging from low to high, corresponding to very low up to completely transparent quality. We then proceed with an in-depth analysis of advantages and drawbacks of each codec for specific types of content and compare the subjective comparisons and conclusions to those obtained by others in the state of the art as well to those measured by means of objective metrics such as PSNR.

  • ICIP - Rate-distortion evaluation for two-layer coding systems
    2015 IEEE International Conference on Image Processing (ICIP), 2015
    Co-Authors: Philippe Hanhart, Touradj Ebrahimi
    Abstract:

    The Bj⊘ntegaard model is widely used to calculate the Compression Efficiency between different codecs. However, this model is not sufficient to investigate the impact on quality of the interaction of the base and enhancement layer bit rates when comparing two-layer coding systems. Therefore, in this paper, we propose an extension of the Bj⊘ntegaard model from rate-distortion (R-D) curve fitting to rate-rate-distortion (R2-D) surface fitting. The proposed model uses a cubic surface as fitting function and a more complex characterization of the domain formed by the data points to compute a more realistic estimate of Compression Efficiency. The proposed model can be used to measure the Compression Efficiency of two-layer coding systems, as well as for other applications, e.g., to optimize the bit rate allocation between texture and depth in 3D video coding. Two examples of assessment of Compression Efficiency in JPEG XT are presented as illustrations.

J W Woods - One of the best experts on this subject based on the ideXlab platform.

  • embedded image coding using zeroblocks of subband wavelet coefficients and context modeling
    International Symposium on Circuits and Systems, 2000
    Co-Authors: Shih-ta Hsiang, J W Woods
    Abstract:

    With fast computation and excellent Compression Efficiency, two embedded coding techniques, zero-tree/-block coding and context modeling of the subband/wavelet coefficients, have been widely utilized for image coding applications. In this research, we present a new embedded wavelet image coding algorithm with an attempt to combine advantages of these two successful coding schemes. The experimental results show that the proposed algorithm outperforms the respected zero-tree/-block coders, SPIHT and SPECK, in Compression Efficiency. It is also comparable to the state-of-art JPEG 2000 test coder in PSNR performance while retaining the attractive low-complexity feature of the zeroblock coders.

  • ISCAS - Embedded image coding using zeroblocks of subband/wavelet coefficients and context modeling
    2000 IEEE International Symposium on Circuits and Systems. Emerging Technologies for the 21st Century. Proceedings (IEEE Cat No.00CH36353), 2000
    Co-Authors: Shih-ta Hsiang, J W Woods
    Abstract:

    With fast computation and excellent Compression Efficiency, two embedded coding techniques, zero-tree/-block coding and context modeling of the subband/wavelet coefficients, have been widely utilized for image coding applications. In this research, we present a new embedded wavelet image coding algorithm with an attempt to combine advantages of these two successful coding schemes. The experimental results show that the proposed algorithm outperforms the respected zero-tree/-block coders, SPIHT and SPECK, in Compression Efficiency. It is also comparable to the state-of-art JPEG 2000 test coder in PSNR performance while retaining the attractive low-complexity feature of the zeroblock coders.

Fernando Pereira - One of the best experts on this subject based on the ideXlab platform.

  • PCS - Improving scalable video coding performance with decoder side information
    2013 Picture Coding Symposium (PCS), 2013
    Co-Authors: Xiem Hoangvan, Joao Ascenso, Fernando Pereira
    Abstract:

    In a heterogeneous landscape of networks, devices and consumption environments, scalability is one of the most important video coding features. To achieve higher scalable video Compression Efficiency, this paper proposes a novel scalable video coding framework based on predictive video coding but also exploiting some additional decoder side information. The side information is estimated at both encoder and decoder using a motion compensated temporal interpolation technique, commonly used in distributed video coding solutions. To improve the B-slices Compression Efficiency, the side information independently created at each coding layer, notably the base and enhancement layers, is inserted in the corresponding layer decoded picture buffer to be exploited as an additional reference frame in the scalable predictive coding process. Experimental results have shown significant Compression Efficiency gains, notably up to around 3.5% in bitrate savings regarding the state-of-the-art SVC standard.

  • Visual Information Processing and Communication - Compression Efficiency analysis of Wyner-Ziv video coding with motion compensated side information interpolation
    Proceedings of SPIE, 2010
    Co-Authors: Joao Ascenso, Catarina Brites, Fernando Pereira
    Abstract:

    The Wyner-Ziv video coding (WZVC) rate distortion performance is highly dependent on the quality of the side information, an estimation of the original frame, created at the decoder. This paper, characterizes the WZVC Efficiency when motion compensated frame interpolation (MCFI) techniques are used to generate the side information, a difficult problem in WZVC especially because the decoder only has available some reference decoded frames. The proposed WZVC Compression Efficiency rate model relates the power spectral of the estimation error to the accuracy of the MCFI motion field. Then, some interesting conclusions may be derived related to the impact of the motion field smoothness and the correlation to the true motion trajectories on the Compression performance.

Shih-ta Hsiang - One of the best experts on this subject based on the ideXlab platform.

  • embedded image coding using zeroblocks of subband wavelet coefficients and context modeling
    International Symposium on Circuits and Systems, 2000
    Co-Authors: Shih-ta Hsiang, J W Woods
    Abstract:

    With fast computation and excellent Compression Efficiency, two embedded coding techniques, zero-tree/-block coding and context modeling of the subband/wavelet coefficients, have been widely utilized for image coding applications. In this research, we present a new embedded wavelet image coding algorithm with an attempt to combine advantages of these two successful coding schemes. The experimental results show that the proposed algorithm outperforms the respected zero-tree/-block coders, SPIHT and SPECK, in Compression Efficiency. It is also comparable to the state-of-art JPEG 2000 test coder in PSNR performance while retaining the attractive low-complexity feature of the zeroblock coders.

  • ISCAS - Embedded image coding using zeroblocks of subband/wavelet coefficients and context modeling
    2000 IEEE International Symposium on Circuits and Systems. Emerging Technologies for the 21st Century. Proceedings (IEEE Cat No.00CH36353), 2000
    Co-Authors: Shih-ta Hsiang, J W Woods
    Abstract:

    With fast computation and excellent Compression Efficiency, two embedded coding techniques, zero-tree/-block coding and context modeling of the subband/wavelet coefficients, have been widely utilized for image coding applications. In this research, we present a new embedded wavelet image coding algorithm with an attempt to combine advantages of these two successful coding schemes. The experimental results show that the proposed algorithm outperforms the respected zero-tree/-block coders, SPIHT and SPECK, in Compression Efficiency. It is also comparable to the state-of-art JPEG 2000 test coder in PSNR performance while retaining the attractive low-complexity feature of the zeroblock coders.