arXiv subjects

Touradj Ebrahimi

Publications and source records attributed to Touradj Ebrahimi.

25 records · Page 2Linked to original sources

arXiv2022

A Novel Framework for Assessment of Learning-based Detectors in Realistic Conditions with Application to Deepfake Detection

Deep convolutional neural networks have shown remarkable results on multiple detection tasks. Despite the significant progress, the performance of such detectors are often assessed in public benchmarks under non-realistic conditions. Specifically, impact of conventional distortions and processing operations such as compression, noise, and enhancement are not sufficiently studied. This paper proposes a rigorous framework to assess performance of learning-based detectors in more realistic situations. An illustrative example is shown under deepfake detection context. Inspired by the assessment results, a data augmentation strategy based on natural image degradation process is designed, which significantly improves the generalization ability of two deepfake detectors.

cs.CV↗

arXiv2022

A New Approach to Improve Learning-based Deepfake Detection in Realistic Conditions

Deep convolutional neural networks have achieved exceptional results on multiple detection and recognition tasks. However, the performance of such detectors are often evaluated in public benchmarks under constrained and non-realistic situations. The impact of conventional distortions and processing operations found in imaging workflows such as compression, noise, and enhancement are not sufficiently studied. Currently, only a few researches have been done to improve the detector robustness to unseen perturbations. This paper proposes a more effective data augmentation scheme based on real-world image degradation process. This novel technique is deployed for deepfake detection tasks and has been evaluated by a more realistic assessment framework. Extensive experiments show that the proposed data augmentation scheme improves generalization ability to unpredictable data distortions and unseen datasets.

cs.CV↗

arXiv2022

Sampling color and geometry point clouds from ShapeNet dataset

The popularisation of acquisition devices capable of capturing volumetric information such as LiDAR scans and depth cameras has lead to an increased interest in point clouds as an imaging modality. Due to the high amount of data needed for their representation, efficient compression solutions are needed to enable practical applications. Among the many techniques that have been proposed in the last years, learning-based methods are receiving large attention due to their high performance and potential for improvement. Such algorithms depend on large and diverse training sets to achieve good compression performance. ShapeNet is a large-scale dataset composed of CAD models with texture and constitute and effective option for training such compression methods. This dataset is entirely composed of meshes, which must go through a sampling process in order to obtain point clouds with geometry and texture information. Although many existing software libraries are able to sample geometry from meshes through simple functions, obtaining an output point cloud with geometry and color of the external faces of the mesh models is not a straightforward process for the ShapeNet dataset. The main difficulty associated with this dataset is that its models are often defined with duplicated faces sharing the same vertices, but with different color values. This document describes a script for sampling the meshes from ShapeNet that circumvent this issue by excluding the internal faces of the mesh models prior to the sampling. The script can be accessed from the following link: https://github.com/mmspg/mesh-sampling.

eess.IV↗

arXiv2021

Impact of Benign Modifications on Discriminative Performance of Deepfake Detectors

Deepfakes are becoming increasingly popular in both good faith applications such as in entertainment and maliciously intended manipulations such as in image and video forgery. Primarily motivated by the latter, a large number of deepfake detectors have been proposed recently in order to identify such content. While the performance of such detectors still need further improvements, they are often assessed in simple if not trivial scenarios. In particular, the impact of benign processing operations such as transcoding, denoising, resizing and enhancement are not sufficiently studied. This paper proposes a more rigorous and systematic framework to assess the performance of deepfake detectors in more realistic situations. It quantitatively measures how and to which extent each benign processing approach impacts a state-of-the-art deepfake detection method. By illustrating it in a popular deepfake detector, our benchmark proposes a framework to assess robustness of detectors and provides valuable insights to design more efficient deepfake detectors.

cs.CV↗

arXiv2019

Digital Watermarking of video streams: Review of the State-Of-The-Art

Digital Watermarking is an extremely wide aspect of information security, either by its applications, by its properties, or by its designs. In particular, a lot of research has been made about video watermarking and it can make it quite difficult to put into perspective the various schemes possible in order to implement a watermarking process for a given application. This paper presents an in-depth overview of the current video watermarking technologies and how they each respond to certain criteria that may be imposed by the aimed application. The goal being in first place to be able to define the desired equilibrium point between invisibility, robustness and efficiency for an application. Then, given this balance, being able to deduce the best location of the information embedding as well as the method used to embed it. The equilibrium point is to be found using the needed properties of the watermark and by studying the threat model that the scheme will have to face. The location describes whether the extra information should be added to the metadata of the video, to its frames or to specific regions of its frames. Finally, the method to embed the watermark refers to the insertion domain and its coefficients to be altered in order to insert the wanted information.

eess.IV↗

arXiv2019

Perceptual Quality Study on Deep Learning based Image Compression

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 perceptual quality studies on learned compression. First, we build a general learned compression approach, and optimize the model. In total six compression algorithms are considered for this study. Then, we perform subjective quality tests in a controlled environment using high-resolution images. Results demonstrate learned compression optimized by MS-SSIM yields competitive results that approach the efficiency of state-of-the-art compression. The results obtained can provide a useful benchmark for future developments in learned image compression.

eess.IV↗

arXiv2017

High Dynamic Range Imaging Technology

In this lecture note, we describe high dynamic range (HDR) imaging systems; such systems are able to represent luminances of much larger brightness and, typically, also a larger range of colors than conventional standard dynamic range (SDR) imaging systems. The larger luminance range greatly improve the overall quality of visual content, making it appears much more realistic and appealing to observers. HDR is one of the key technologies of the future imaging pipeline, which will change the way the digital visual content is represented and manipulated today.

cs.GR↗