Search Results for author: Christos Tzelepis

Found 20 papers, 14 papers with code

DiffusionAct: Controllable Diffusion Autoencoder for One-shot Face Reenactment

no code implementations25 Mar 2024 Stella Bounareli, Christos Tzelepis, Vasileios Argyriou, Ioannis Patras, Georgios Tzimiropoulos

To this end, in this paper we present DiffusionAct, a novel method that leverages the photo-realistic image generation of diffusion models to perform neural face reenactment.

Face Reenactment Image Generation

Multilinear Mixture of Experts: Scalable Expert Specialization through Factorization

1 code implementation19 Feb 2024 James Oldfield, Markos Georgopoulos, Grigorios G. Chrysos, Christos Tzelepis, Yannis Panagakis, Mihalis A. Nicolaou, Jiankang Deng, Ioannis Patras

The Mixture of Experts (MoE) paradigm provides a powerful way to decompose inscrutable dense layers into smaller, modular computations often more amenable to human interpretation, debugging, and editability.

Attribute counterfactual

One-shot Neural Face Reenactment via Finding Directions in GAN's Latent Space

no code implementations5 Feb 2024 Stella Bounareli, Christos Tzelepis, Vasileios Argyriou, Ioannis Patras, Georgios Tzimiropoulos

Moreover, we show that by embedding real images in the GAN latent space, our method can be successfully used for the reenactment of real-world faces.

Disentanglement Face Reenactment

HyperReenact: One-Shot Reenactment via Jointly Learning to Refine and Retarget Faces

1 code implementation ICCV 2023 Stella Bounareli, Christos Tzelepis, Vasileios Argyriou, Ioannis Patras, Georgios Tzimiropoulos

In this paper, we present our method for neural face reenactment, called HyperReenact, that aims to generate realistic talking head images of a source identity, driven by a target facial pose.

Face Reenactment

Parts of Speech-Grounded Subspaces in Vision-Language Models

2 code implementations23 May 2023 James Oldfield, Christos Tzelepis, Yannis Panagakis, Mihalis A. Nicolaou, Ioannis Patras

Latent image representations arising from vision-language models have proved immensely useful for a variety of downstream tasks.

Image Generation POS +1

Attribute-preserving Face Dataset Anonymization via Latent Code Optimization

1 code implementation CVPR 2023 Simone Barattin, Christos Tzelepis, Ioannis Patras, Nicu Sebe

By optimizing the latent codes directly, we ensure both that the identity is of a desired distance away from the original (with an identity obfuscation loss), whilst preserving the facial attributes (using a novel feature-matching loss in FaRL's deep feature space).

Attribute

StyleMask: Disentangling the Style Space of StyleGAN2 for Neural Face Reenactment

1 code implementation27 Sep 2022 Stella Bounareli, Christos Tzelepis, Vasileios Argyriou, Ioannis Patras, Georgios Tzimiropoulos

In this paper we address the problem of neural face reenactment, where, given a pair of a source and a target facial image, we need to transfer the target's pose (defined as the head pose and its facial expressions) to the source image, by preserving at the same time the source's identity characteristics (e. g., facial shape, hair style, etc), even in the challenging case where the source and the target faces belong to different identities.

Disentanglement Face Reenactment

ContraCLIP: Interpretable GAN generation driven by pairs of contrasting sentences

1 code implementation5 Jun 2022 Christos Tzelepis, James Oldfield, Georgios Tzimiropoulos, Ioannis Patras

This work addresses the problem of discovering non-linear interpretable paths in the latent space of pre-trained GANs in a model-agnostic manner.

Position

PandA: Unsupervised Learning of Parts and Appearances in the Feature Maps of GANs

1 code implementation31 May 2022 James Oldfield, Christos Tzelepis, Yannis Panagakis, Mihalis A. Nicolaou, Ioannis Patras

Recent advances in the understanding of Generative Adversarial Networks (GANs) have led to remarkable progress in visual editing and synthesis tasks, capitalizing on the rich semantics that are embedded in the latent spaces of pre-trained GANs.

WarpedGANSpace: Finding non-linear RBF paths in GAN latent space

1 code implementation ICCV 2021 Christos Tzelepis, Georgios Tzimiropoulos, Ioannis Patras

This work addresses the problem of discovering, in an unsupervised manner, interpretable paths in the latent space of pretrained GANs, so as to provide an intuitive and easy way of controlling the underlying generative factors.

DnS: Distill-and-Select for Efficient and Accurate Video Indexing and Retrieval

1 code implementation24 Jun 2021 Giorgos Kordopatis-Zilos, Christos Tzelepis, Symeon Papadopoulos, Ioannis Kompatsiaris, Ioannis Patras

In this work, we propose a Knowledge Distillation framework, called Distill-and-Select (DnS), that starting from a well-performing fine-grained Teacher Network learns: a) Student Networks at different retrieval performance and computational efficiency trade-offs and b) a Selector Network that at test time rapidly directs samples to the appropriate student to maintain both high retrieval performance and high computational efficiency.

Computational Efficiency Knowledge Distillation +2

Few-Shot Action Localization without Knowing Boundaries

1 code implementation8 Jun 2021 Ting-Ting Xie, Christos Tzelepis, Fan Fu, Ioannis Patras

Learning to localize actions in long, cluttered, and untrimmed videos is a hard task, that in the literature has typically been addressed assuming the availability of large amounts of annotated training samples for each class -- either in a fully-supervised setting, where action boundaries are known, or in a weakly-supervised setting, where only class labels are known for each video.

Action Localization Few-Shot Learning

Uncertainty Propagation in Convolutional Neural Networks: Technical Report

2 code implementations11 Feb 2021 Christos Tzelepis, Ioannis Patras

In this technical report we study the problem of propagation of uncertainty (in terms of variances of given uni-variate normal random variables) through typical building blocks of a Convolutional Neural Network (CNN).

Temporal Action Localization with Variance-Aware Networks

no code implementations25 Aug 2020 Ting-Ting Xie, Christos Tzelepis, Ioannis Patras

Results in the action localization problem show that the incorporation of second order statistics improves over the baseline network, and that VANp surpasses the accuracy of virtually all other two-stage networks without involving any additional parameters.

regression Temporal Action Localization

Boundary Uncertainty in a Single-Stage Temporal Action Localization Network

no code implementations25 Aug 2020 Ting-Ting Xie, Christos Tzelepis, Ioannis Patras

We use two uncertainty-aware boundary regression losses: first, the Kullback-Leibler divergence between the ground truth location of the boundary and the Gaussian modeling the prediction of the boundary and second, the expectation of the $\ell_1$ loss under the same Gaussian.

Temporal Action Localization

Linear Maximum Margin Classifier for Learning from Uncertain Data

1 code implementation15 Apr 2015 Christos Tzelepis, Vasileios Mezaris, Ioannis Patras

In this paper, we propose a maximum margin classifier that deals with uncertainty in data input.

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