Publications de Touradj Ebrahimi

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This paper investigates the influence of the combination of the scalability parameters in scalable video coding (SVC) schemes on the subjective visual quality. We aim at providing guidelines for an adaptation strategy of SVC that can select the optimal sca ...

Deepfakes first came to prominence less than five years ago. Since then, they have surged in quantity and quality, becoming both a source of viral entertainment and of concern about the dark side of digital life. In this article, we provide a risk governan ...

In this paper, we consider the challenging problem of object duplicate detection and localization. Several applications require efficient object duplicate detection methods, such as automatic video and image tagging, video surveillance, and high level imag ...

Extensive adoption of video surveillance, affecting many aspects of the daily life, alarms the concerned public about the increasing invasion into personal privacy. To address these concerns, many tools have been proposed for protection of personal privacy ...

Cross-resolution face recognition has become a challenging problem for modern deep face recognition systems. It aims at matching a low-resolution probe image with high-resolution gallery images registered in a database. Existing methods mainly leverage pri ...

With the increasing use of multimedia technologies, image compression requires higher performance as well as new features. To address this need in the specific area of still image encoding, a new standard is currently being developed, the JPEG2000. It is not only intended to provide rate-distortion and subjective image quality performance superior to existing standards, but also to provide features and functionalities that current standards can either not address efficiently or in many cases cannot address

Emerging new imaging technologies, such as HDR (High Dynamic Range) or UHD (Ultra High Definition), have a significant impact in various applications. One of them, namely, visual privacy protection in video surveillance is an important and increasingly popular research topic. To evaluate the influence of new imaging technologies, a suitable dataset of images and video sequences is needed. However, there are only few datasets for testing performance of various algorithms on above mentioned applications, and

The Joint Photographic Experts Group (JPEG) has recently rolled out a new still image coding standard called JPEG 2000. This standard integrates an efficient image compression scheme along with functionalities required by multimedia applications, such as progressiveness up to lossless coding, region of interest coding, and error resiliency. Security is a concern in many applications, and therefore a highly desired functionality. For this reason, JPEG recently initiated an activity known as secure JPEG 2000

A correlation map shows the correlation between an image region and another image computed at the neighbourhood of each point of the second image. Most cross-correlation techniques fail when the viewpoint rotation grows over a certain value, usually around 20 degrees. The approach presented here aims at resolving this problem and at the same time provide an estimate of the actual rotation. This paper presents a method to obtain a correlation map robust to rotation together with an orientation map that gives

Video consumption over Internet has increased significantly over the recent years and occupies the majority of the overall data traffic. To decrease the load on the Internet infrastructure and reduce bandwidth taken by video, higher efficiency video codecs ...

With the technological evolution of digital acquisition and content analysis, millions of images and video sequences are captured every day and used in a large variety of applications. As keyword-based indexing is very time consuming and inefficient due to ...

Shadows are integral parts of natural scenes and one of the elements contributing to naturalness of synthetic scenes. In many image analysis and interpretation applications, shadows interfere with fundamental tasks such as object extraction and description. For this reason, shadow segmentation is an important step in image analysis. In this paper, we propose a new cast shadow segmentation algorithm for both still and moving images. The proposed technique exploits spectral and geometrical properties of shado

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 ...

Event-related potentials (ERPs) are indicators of brain activity related to cognitive processes. They can be detected from EEG signals and thus constitute an attractive non-invasive option to study cognitive information processing. The P300 wave is probabl ...

In recent years, light field has experienced a surge of popularity, mainly due to the recent advances in acquisition and rendering technologies that have made it more accessible to the public. Thanks to image-based rendering techniques, light field contents can be rendered in real time on common 2D screens, allowing virtual navigation through the captured scenes in an interactive fashion. However, this richer representation of the scene poses the problem of reliable quality assessments for light field conte

The reliable evaluation of the performance of watermarking algorithms is difficult. An important aspect in this process is the assessment of the visibility of the watermark. In this paper, we address this issue and propose a methodology for evaluating the visual quality of watermarked video. Using a software tool that measures different types of perceptual video artifacts, we determine the most relevant impairments and design the corresponding objective metrics. We demonstrate their performance through subj

Change detection generally is the difference between images. The differences or changes could be due to moving objects or a variation of illumination. In general the goal is to extract only changes due to moving object that occur int eh scene, and to ignore changes due to illumination. A requirement is that the detection has to be performed in real-time. The proposed change detection approach relies on a model assigning a vector to every pixel of the reference and the current image. Based on this model, lin

Recent advances in depth sensing and display technologies, along with the significant growth of interest for augmented and virtual reality applications, lay the foundation for the rapid evolution of applications that provide immersive experiences. In such ...

The Electroencephalogram (EEG) is a recording of the electrical potentials generated by brain activity on the scalp. It has been used for decades as a non-invasive tool both in fundamental brain research and in clinical diagnosis. But it is now widely used also in Brain-Computer Interfaces (BCI) to provide augmentative communication mainly for severely handicapped patients and, prospectively, in the general framework of human computer interaction. As in any communication system, the input (EEG activity) mus

The image identification problem consists in identifying all the equivalent forms of a given reference image. An image is equivalent to the reference image, if the former results from the application of an image operator (or a composition of image operators) to the latter. Depending on the application, different sets of image operators are considered. The equivalence quantification is done in three levels. In the first level, we construct the set of equivalent images which is composed of the reference and i

Touradj Ebrahimi

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Subjective evaluation of scalable video coding for content distribution

Risk governance and the rise of deepfakes

Graph-Based Approach for 3D Object Duplicate Detection

Crowdsourcing Approach for Evaluation of Privacy Filters in Video Surveillance

Cross-resolution Face Recognition via Identity-Preserving Network and Knowledge Distillation

The JPEG2000 still image coding system: An overview

A new database of still and moving High Dynamic Range pictures

Securing JPEG 2000 compressed images

Rotation correlation maps

Quality Evaluation of HEVC and VP9 Video Compression in Real-Time Applications

Omnidirectional object duplicate detection

Cast shadow segmentation using invariant colour features

Towards Modelling of Visual Saliency in Point Clouds for Immersive Applications

Curiosity Cloning: Neural Analysis of Scientific Knowledge

A new framework for interactive quality assessment with application to light field coding

Perceptual Quality Assessment for Video Watermarking

Improved linear dependence and vector model for illumination-invariant change detection

Benchmarking of Objective Quality Metrics for Colorless Point Clouds

Human-Brain Interface: Signal Processing and Machine Learning

Images Identification Based on Equivalence Classes