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Touradj Ebrahimi

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Publications associées (306)

PointXR: A Toolbox for Visualization and Subjective Evaluation of Point Clouds in Virtual Reality

Touradj Ebrahimi, Evangelos Alexiou, Nanyang Yang

In this study, we explore the use of virtual reality to subjectively evaluate the visual quality of point cloud contents. To this aim, we develop the PointXR toolbox, a set of Unity applications that can host experiments under variants of interactive and p ...

IEEE2020

Comprehensive assessment of image compression algorithms

Touradj Ebrahimi, Evgeniy Upenik, Michela Testolina

JPEG image coding standard has been a dominant format in a wide range of applications in soon three decades since it has been released as an international standard. The landscape of applications and services based on pictures has evolved since the original ...

SPIE2020

Privacy-preserving photo sharing based on blockchain

Touradj Ebrahimi, Pablo Pfister

Sharing photos online has become an extremely popular activity, raising a wide concern on privacy issues related to the shared content. ProShare, a photo-sharing solution developed by Multimedia Signal Processing Group of EPFL addresses some of these priva ...

SPIE-INT SOC OPTICAL ENGINEERING2020

Quality Evaluation Of Static Point Clouds Encoded Using MPEG Codecs

Touradj Ebrahimi, Evangelos Alexiou

This paper presents a quality evaluation study of point cloud codecs that have been recently standardised by the MPEG committee. In particular, a subjective experiment to assess their performance in terms of bitrate against visual quality is designed and r ...

IEEE2020

Inpainting in Omnidirectional Images for Privacy Protection

Touradj Ebrahimi, Pinar Akyazi, Evgeniy Upenik

Privacy protection is drawing more attention with the advances in image processing, visual and social media. Photo sharing is a popular activity, which also brings the concern of regulating permissions associated with shared content. This paper presents a ...

2019

Light field compression using translation-assisted view estimation

Touradj Ebrahimi, Irene Viola

Light field technology has recently been gaining traction in the research community. Several acquisition technologies have been demonstrated to properly capture light field information, and portable devices have been commercialized to the general public. H ...

IEEE2019

An in-depth analysis of single-image subjective quality assessment of light field contents

Touradj Ebrahimi, Irene Viola

Quality assessment of light field images poses new questions and challenges, due to the enriched nature of the content and the possibilities it offers at the rendering step. Image-based rendering is conventionally used to showcase the increased capabilitie ...

2019

Learning-Based Image Compression using Convolutional Autoencoder and Wavelet Decomposition

Touradj Ebrahimi, Pinar Akyazi

In this paper, a learning-based image compression method that employs wavelet decomposition as a preprocessing step is presented. The proposed convolutional autoencoder is trained end-to-end to yield a target bitrate smaller than 0.15 bits per pixel across ...

2019

Overview and Evaluation of the JPEG XT HDR Image Compression Standard

Touradj Ebrahimi, Philippe Hanhart

Standards play an important role in providing a common set of specifications and allowing inter-operability between devices and systems. Until recently, no standard for High Dynamic Range (HDR) image coding had been adopted by the market, and HDR imaging r ...

2019

Perceptual Quality Study On Deep Learning Based Image Compression

Touradj Ebrahimi, Pinar Akyazi

Recently deep learning based image compression has made rapid advances with promising results based on objective quality metrics. However, a rigorous subjective quality evaluation on such compression schemes have rarely been reported. This paper aims at pe ...

IEEE2019

A comprehensive study of the rate-distortion performance in MPEG point cloud compression

Touradj Ebrahimi, Irene Viola, Evangelos Alexiou

Recent trends in multimedia technologies indicate the need for richer imaging modalities to increase user engagement with the content. Among other alternatives, point clouds denote a viable solution that offers an immersive content representation, as witne ...

2019

Saliency Driven Perceptual Quality Metric for Omnidirectional Visual Content

Touradj Ebrahimi, Evgeniy Upenik

The problem of objectively measuring perceptual quality of omnidirectional visual content arises in many immersive imaging applications and particularly in compression. The interactive nature of this type of content limits the performance of earlier method ...

IEEE2019

Point cloud quality evaluation: Towards a definition for test conditions

Touradj Ebrahimi, Rafael Xavier Meriade Duarte, Evangelos Alexiou

Recently stakeholders in the area of multimedia representation and transmission have been looking at plenoptic technologies to improve immersive experience. Among these technologies, point clouds denote a volumetric information representation format with i ...

2019

A comprehensive framework for visual quality assessment of light field tensor displays

Touradj Ebrahimi, Irene Viola

In recent years, light field technology has attracted the interest of academia and industry, thanks to the possibility of rendering 3D scenes in a more realistic and immersive way. In particular, light field displays have been consistently investigated for ...

Society for Imaging Science and Technology2019

Rendering-dependent compression and quality evaluation for light field contents

Touradj Ebrahimi, Irene Viola

Light field representation promises to overcome the limitations of stereoscopic representation by allowing for a more seamless transition between multiple points of views, thus giving a more faithful representation of 3D scenes. However, in order to take f ...

2019

Exploiting user interactivity in quality assessment of point cloud imaging

Touradj Ebrahimi, Evangelos Alexiou

Point clouds are a new modality for representation of plenoptic content and a popular alternative to create immersive media. Despite recent progress in capture, display, storage, delivery and processing, the problem of a reliable approach to subjectively a ...

2019

JPEG Pleno: Providing representation interoperability for holographic applications and devices

Touradj Ebrahimi

Guaranteeing interoperability between devices and applications is the core role of standards organizations. Since its first JPEG standard in 1992, the Joint Photographic Experts Group (JPEG) has published several image coding standards that have been succe ...

WILEY2019

Towards Modelling of Visual Saliency in Point Clouds for Immersive Applications

Touradj Ebrahimi, Evangelos Alexiou, Peisen Xu

Modelling human visual attention is of great importance in the field of computer vision and has been widely explored for 3D imaging. Yet, in the absence of ground truth data, it is unclear whether such predictions are in alignment with the actual human vie ...

2019

Point Cloud Quality Assessment Metric Based on Angular Similarity

Touradj Ebrahimi, Evangelos Alexiou

The rise of immersive technologies has been recently fuelled by emerging applications which employ advanced content representations. Among various alternatives, point clouds denote a promising solution which has recently drawn a significant amount of inter ...

2018

Comparison of Compression Efficiency between HEVC/H.265, VP9 and AV1 based on Subjective Quality Assessments

Touradj Ebrahimi, Pinar Akyazi

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 ...

2018

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