Publications by Touradj Ebrahimi

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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 ...

Evaluation is a central issue in the design, implementation, and performance assessment of all systems. Recently, a number of metrics have been proposed to assess the performance of segmentation algorithms for image and video data. This paper provides an overview of state of the art metrics proposed so-far, and introduces a new and efficient such metric. Doing so, subjective experiments are carried out to derive a perceptual metric. As a result, it also provides a comparison of performance of segmentation a

This paper describes the details and the results of the subjective quality evaluation performed at EPFL, as a contribution to the effort of the Joint Collaborative Team on Video Coding (JCT-VC) for the definition of the next-generation video coding standard. The performance of 27 coding technologies have been evaluated with respect to two H.264/MPEG-4 AVC anchors, considering high definition (HD) test material. The test campaign involved a total of 494 naive observers and took place over a period of four we

Scalable video coding is a powerful solution for content delivery in many interactive multimedia services due to its adaptability to varying terminal and network constraints. In order to successfully exploit such adaptability, it is necessary to understand ...

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 ...

A brain-computer interface (BCI) is a communication system that translates brain-activity into commands for a computer or other devices. In other words, a BCI allows users to act on their environment by using only brain-activity, without using peripheral n ...

JPEG XR is the newest image coding standard from the JPEG committee. It primarily targets the representation of continuous-tone still images such as photographic images, and achieves high image quality, on par with JPEG 2000, while requiring low computatio ...

Over the past years, image generation and manipulation have achieved remarkable progress due to the rapid development of generative AI based on deep learning. Recent studies have devoted significant efforts to address the problem of face image manipulation ...

In this paper, we propose a Secure JPEG, an open and flexible standardized framework to secure JPEG images. Its goal is to allow the efficient integration and use of security tools enabling a variety of security services such as confidentiality, integrity ...

The performance of existing DVC codecs is still lacking relative to that of H.264 and work is being carried out in order to close this gap. The authors of this paper have been and still are involved in the development of two DVC codecs respectively, the pe ...

Point clouds are among popular visual representations for immersive media. However, the vast amount of information generated during their acquisition requires effective compression for practical applications. Although relevant activities from standardizati ...

Omnidirectional image and video have gained popularity thanks to availability of capture and display devices for this type of content. Recent studies have assessed performance of objective metrics in predicting visual quality of omnidirectional content. Th ...

Point clouds allow for the representation of 3D multimedia content as a set of disconnected points in space. Their inher- ent irregular geometric nature poses a challenge to efficient compression, a critical operation for both storage and trans- mission. This paper proposes a VAE-inspired codec tailored for dynamic point cloud geometry compression, taking ad- vantage of a temporal autoregressive hyperprior to enhance compression performance. Specifically, features derived from adjacent point cloud frames he

Autonomous decision making modules in computer vision application allow recognition and classification of different objects, persons, and events in images and video sequences and also make it possible to classify different sensor readings (e.g. images) acc ...

This paper proposes a new method for bimodal information fusion in audio-visual speech recognition, where cross-modal association is considered in two levels. First, the acoustic and the visual data streams are combined at the feature level by using the ca ...

An algorithm for feature point extraction is presented. It is based on a scale-space representation of the image as well as a system for tracking across scales. Using synthetic and real images, it is shown that the proposed algorithm produces stable and well-localized feature points estimates two essential properties for video applications.

This paper presents the design and the results of a psychovisual experiment which aims at understanding how the color information affects the perceived quality of a high resolution still picture. The results of this experiment help to shed light into the i ...

Objective quality assessment of compressed images is very useful in many applications. In this paper we present an objective quality metric that is better tuned to evaluate the quality of images distorted by compression artifacts. A deep convolutional neural networks is used to extract features from a reference image and its distorted version. Selected features have both spatial and spectral characteristics providing substantial information on perceived quality. These features are extracted from numerous ra

Recent past has seen a lot of developments in the field of image-based dietary assessment. Food image classification and recognition are crucial steps for dietary assessment. In the last couple of years, advancements in the deep learning and convolutional ...

Different formats and compression algorithms have been proposed for 3D video content, but 3D images are still mostly represented as a stereo pair only. However, for enhanced 3D rendering capabilities, such as depth perception adjustment or display size ada ...

Touradj Ebrahimi

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Quality Evaluation Of Static Point Clouds Encoded Using MPEG Codecs

On Evaluating Metrics For Video Segmentation Algorithms

Subjective Evaluation of Next-Generation Video Compression Algorithms: A Case Study

Subjective quality evaluation via paired comparison: application to scalable video coding

Learning-Based Image Compression using Convolutional Autoencoder and Wavelet Decomposition

An efficient P300-based brain-computer interface for disabled subjects

The JPEG XR Image Coding Standard

Towards the Detection of AI-Synthesized Human Face Images

Toward a secure JPEG

Performance evaluation of two state of the art DVC codecs

On Block Prediction For Learning-Based Point Cloud Compression

On the performance of objective metrics for omnidirectional visual content

Temporal Conditional Coding for Dynamic Point Cloud Geometry Compression

The Impact of Expertise on Brain Computer Interface Based Salient Image Retrieval

Two-level bimodal association for audio-visual speech recognition

Feature point extraction using scale-space representation

A subjective study of the influence of color information on visual quality assessment of high resolution pictures

An improved objective metric to predict image quality using deep neural networks

Food/Non-food Image Classification and Food Categorization using Pre-Trained GoogLeNet Model

JPEG backward compatible format for 3D content representation