Publications de Touradj Ebrahimi

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Face detection allows to recognize and detect human faces and provides information about their location in a given image. Many applications such as biometrics, face recognition, and video surveillance employ face detection as one of their main modules. The ...

DNA is an excellent medium for efficient storage of information. Not only it offers a long-term and robust mechanism but also it is environmental friendly and has an unparalleled storage capacity, However, the basic elements in DNA are quaternary, and therefore there is a need for efficient coding of information in quaternary representation while taking into account various biochemical constraints involved. Such constraints create additional complexity on how information should be represented in quaternary

With the exponential growth of digital data production, conventional storage technologies face increasing challenges related to scalability, durability, and environmental impact. DNA has emerged as a promising alternative storage medium due to its exceptional density, longevity, and sustainability. In this context, the JPEG Committee (ISO/IEC JTC 1/SC 29/WG 1) has developed the JPEG DNA standard (ISO/IEC 25508), the first specification for image coding on synthetic DNA, which is currently in its final stage

Point clouds have been gaining importance as a solution to the problem of efficient representation of 3D geometric and visual information. They are commonly represented by large amounts of data, and compression schemes are important for their manipulation ...

Advances in image compression, storage, and display technologies have made high-quality images and videos widely accessible. At this level of quality, distinguishing between compressed and original content becomes difficult, highlighting the need for asses ...

High Dynamic Range (HDR) imaging is expected, together with ultra-high definition (UHD) and high frame rate (HFR) video, to become a technology that may change photo, TV, and film industries. Many cameras and displays capable of capturing and rendering bot ...

In this paper, the analysis of a subjective quality experiment consisting in assessing the quality of free-viewpoint video sequences generated from decompressed depth data is presented. In the absence of a dedicated subjective assessment protocol for the e ...

New emerging technologies in the field of multimedia, such as high dynamic range and wide color gamut, challenge the performance of existing image and video data processing algorithms, especially in terms of visual data compression and its faithful represe ...

The Bjontegaard 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 ...

While 3D display technologies are already widely available for cinema and home or corporate use, only a few portable devices currently feature 3D display capabilities. Moreover, the large majority of 3D display solutions rely on binocular perception. In th ...

Lossy image compression is a popular, simple and effective solution to reduce the amount of data representing digital pictures. In most lossy compression methods, the reduced volume of data in bits is achieved at the expense of introducing visual artifacts ...

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 JPEC2000. 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

In this paper, we first review the on-going JPSEC standardization activity. Its goal is to extend the baseline JPEG 2000 specification to provide a standardized framework for secure imaging, in order to support tools needed to secure digital images, such as content protection, data integrity check, authentication, and conditional access control. We then present two examples of JPSEC tools. The first one is a technique for secure scalable streaming and secure transcoding. It allows the protected JPSEC codest

Motion estimation is a key issue in video coding. In very low bitrate applications, the amount of the side information for the motion field presents an important portion of the total bitrate. This paper presents a joint motion estimation, segmentation and coding technique, which tries to reduce the segmentation and motion side information, while providing a similar or smaller prediction error when compared to more classical motion estimation techniques. The main application in mind is a region based coding

Evaluating the visual quality of distorted images is a crucial task in the field of image compression, as artifacts may significantly impair the appeal and fidelity of images, therefore reducing the user experience. As assessing the visual quality of image ...

This paper presents a fingerprinting method based on equivalence classes. An equivalence class is composed of a reference image and all its variations (or replicas). For each reference image, a decision function is built. The latter determines if a given image belongs to its corresponding equivalence class. This function is built in three steps: synthesis, projection, and analysis. In the first step, the reference image is replicated using different image operators (like JPEG compression, average filtering,

Acquiring and exchanging a large number of pictures has become nowadays a common practice. Therefore, new image compression solutions to optimize the storage resources are in constant demand. In this context, it is essential to have a solid methodology to evaluate the performance of compression techniques. Such performance is usually measured through objective quality metrics, which are fast and inexpensive but not always reliable. However, performance is best assessed through subjective image quality asses

When a stereo pair is formed from a decoded view and a synthesized view, it is unclear how the overall quality of the stereo pair should be assessed through objective quality metrics. In this paper, this problem is addressed considering a 3D video represen ...

This paper reports the details and results of the subjective evaluations conducted at EPFL to evaluate the responses to the Call for Evidence (CfE) for High Dynamic Range (HDR) and Wide Color Gamut (WCG) Video Coding issued by Moving Picture Experts Group (MPEG). The CfE on HDR/WCG Video Coding aims to explore whether the coding efficiency and/or the functionality of the current version of HEVC standard can be significantly improved for HDR and WCG content. In total, nine submissions, five for Category 1 an

The Quality of Experience (QoE) provided by autostereoscopic 3D displays strongly depends on the user position. For an optimal image quality, the observer should be located at one of the relevant positions, called sweet spots, where artifacts reducing the ...

Touradj Ebrahimi

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Face Detection Using Discrete Gabor Jets And Color Information

Towards effective visual information storage on DNA support

Overview of JPEG DNA coding system for image storage on synthetic DNA

Point cloud subjective evaluation methodology based on reconstructed surfaces

Fine-Grained Subjective Visual Quality Assessment for High-Fidelity Compressed Images

Context-dependent JPEG backward-compatible high-dynamic range image compression

A quality assessment protocol for Free-viewpoint video sequences synthesized from decompressed depth data

Evaluation of ICtCp color space and an Adaptive Reshaper for HDR and WCG

Rate-Distortion Evaluation for Two-Layer Coding Systems

Motion Parallax Based Restitution of 3D Images on Legacy Consumer Mobile Devices

Performance Evaluation of Objective Image Quality Metrics on Conventional and Learning-Based Compression Artifacts

The JPEG 2000 still image compression standard

JPSEC for Secure Imaging in JPEG 2000

Joint motion estimation and segmentation for very low bit rate video coding

Benchmarking conventional and learning-based objective image quality metrics on compression artifacts

Identification of Image Variations based on Equivalence Classes

Review of subjective quality assessment methodologies and standards for compressed images evaluation

Quality Assessment of Asymmetric Stereo Pair Formed From Decoded and Synthesized Views

Towards high dynamic range extensions of HEVC: subjective evaluation of potential coding technologies

Subjective evaluation of an active crosstalk reduction system for mobile autostereoscopic displays