Search Results for author: Richard Hartley

Found 69 papers, 26 papers with code

Severity Controlled Text-to-Image Generative Model Bias Manipulation

no code implementations3 Apr 2024 Jordan Vice, Naveed Akhtar, Richard Hartley, Ajmal Mian

Charting the susceptibility of T2I models to such manipulation, we first expose the new possibility of a dynamic and computationally efficient exploitation of model bias by targeting the embedded language models.

Backdoor Attack Prompt Engineering

Motion Mamba: Efficient and Long Sequence Motion Generation with Hierarchical and Bidirectional Selective SSM

1 code implementation12 Mar 2024 Zeyu Zhang, Akide Liu, Ian Reid, Richard Hartley, Bohan Zhuang, Hao Tang

Human motion generation stands as a significant pursuit in generative computer vision, while achieving long-sequence and efficient motion generation remains challenging.

Quantifying Bias in Text-to-Image Generative Models

no code implementations20 Dec 2023 Jordan Vice, Naveed Akhtar, Richard Hartley, Ajmal Mian

Bias in text-to-image (T2I) models can propagate unfair social representations and may be used to aggressively market ideas or push controversial agendas.

Hallucination Marketing

IMPUS: Image Morphing with Perceptually-Uniform Sampling Using Diffusion Models

1 code implementation12 Nov 2023 Zhaoyuan Yang, Zhengyang Yu, Zhiwei Xu, Jaskirat Singh, Jing Zhang, Dylan Campbell, Peter Tu, Richard Hartley

We present a diffusion-based image morphing approach with perceptually-uniform sampling (IMPUS) that produces smooth, direct and realistic interpolations given an image pair.

Image Generation Image Morphing

BAGM: A Backdoor Attack for Manipulating Text-to-Image Generative Models

1 code implementation31 Jul 2023 Jordan Vice, Naveed Akhtar, Richard Hartley, Ajmal Mian

Based on the penetration level, BAGM takes the form of a suite of attacks that are referred to as surface, shallow and deep attacks in this article.

Backdoor Attack Language Modelling +2

LDP: Language-driven Dual-Pixel Image Defocus Deblurring Network

no code implementations19 Jul 2023 Hao Yang, Liyuan Pan, Yan Yang, Richard Hartley, Miaomiao Liu

In this paper, we propose, to the best of our knowledge, the first framework that introduces the contrastive language-image pre-training framework (CLIP) to accurately estimate the blur map from a DP pair unsupervisedly.

Deblurring Image Defocus Deblurring

Probabilistic and Semantic Descriptions of Image Manifolds and Their Applications

no code implementations6 Jul 2023 Peter Tu, Zhaoyuan Yang, Richard Hartley, Zhiwei Xu, Jing Zhang, Yiwei Fu, Dylan Campbell, Jaskirat Singh, Tianyu Wang

This paper begins with a description of methods for estimating image probability density functions that reflects the observation that such data is usually constrained to lie in restricted regions of the high-dimensional image space-not every pattern of pixels is an image.

Adversarial Purification with the Manifold Hypothesis

no code implementations26 Oct 2022 Zhaoyuan Yang, Zhiwei Xu, Jing Zhang, Richard Hartley, Peter Tu

In this work, we formulate a novel framework for adversarial robustness using the manifold hypothesis.

Adversarial Robustness Variational Inference

Contact-aware Human Motion Forecasting

1 code implementation8 Oct 2022 Wei Mao, Miaomiao Liu, Richard Hartley, Mathieu Salzmann

In this paper, we tackle the task of scene-aware 3D human motion forecasting, which consists of predicting future human poses given a 3D scene and a past human motion.

Human Pose Forecasting Motion Forecasting

Manifold Learning Benefits GANs

no code implementations CVPR 2022 Yao Ni, Piotr Koniusz, Richard Hartley, Richard Nock

In our design, the manifold learning and coding steps are intertwined with layers of the discriminator, with the goal of attracting intermediate feature representations onto manifolds.

Denoising

Semi-Supervised 3D Hand Shape and Pose Estimation with Label Propagation

no code implementations30 Nov 2021 Samira Kaviani, Amir Rahimi, Richard Hartley

To obtain 3D annotations, we are restricted to controlled environments or synthetic datasets, leading us to 3D datasets with less generalizability to real-world scenarios.

Pose Estimation

Dense Uncertainty Estimation via an Ensemble-based Conditional Latent Variable Model

no code implementations22 Nov 2021 Jing Zhang, Yuchao Dai, Mehrtash Harandi, Yiran Zhong, Nick Barnes, Richard Hartley

Uncertainty estimation has been extensively studied in recent literature, which can usually be classified as aleatoric uncertainty and epistemic uncertainty.

Attribute object-detection +1

Invertible Attention

1 code implementation16 Jun 2021 Jiajun Zha, Yiran Zhong, Jing Zhang, Richard Hartley, Liang Zheng

Attention has been proved to be an efficient mechanism to capture long-range dependencies.

Image Reconstruction

One Ring to Rule Them All: a simple solution to multi-view 3D-Reconstruction of shapes with unknown BRDF via a small Recurrent ResNet

no code implementations11 Apr 2021 Ziang Cheng, Hongdong Li, Richard Hartley, Yinqiang Zheng, Imari Sato

This paper proposes a simple method which solves an open problem of multi-view 3D-Reconstruction for objects with unknown and generic surface materials, imaged by a freely moving camera and a freely moving point light source.

3D Reconstruction Multi-View 3D Reconstruction +3

Learning to Estimate Hidden Motions with Global Motion Aggregation

2 code implementations ICCV 2021 Shihao Jiang, Dylan Campbell, Yao Lu, Hongdong Li, Richard Hartley

We demonstrate that the optical flow estimates in the occluded regions can be significantly improved without damaging the performance in non-occluded regions.

Optical Flow Estimation

Learning Optical Flow from a Few Matches

1 code implementation CVPR 2021 Shihao Jiang, Yao Lu, Hongdong Li, Richard Hartley

In this paper, we show that the dense correlation volume representation is redundant and accurate flow estimation can be achieved with only a fraction of elements in it.

Optical Flow Estimation

Few-shot Weakly-Supervised Object Detection via Directional Statistics

no code implementations25 Mar 2021 Amirreza Shaban, Amir Rahimi, Thalaiyasingam Ajanthan, Byron Boots, Richard Hartley

When the novel objects are localized, we utilize them to learn a linear appearance model to detect novel classes in new images.

Multiple Instance Learning Object +3

RANP: Resource Aware Neuron Pruning at Initialization for 3D CNNs

1 code implementation9 Feb 2021 Zhiwei Xu, Thalaiyasingam Ajanthan, Vibhav Vineet, Richard Hartley

In this work, we introduce a Resource Aware Neuron Pruning (RANP) algorithm that prunes 3D CNNs at initialization to high sparsity levels.

3D Semantic Segmentation Stereo Matching +1

Uncertainty-Aware Deep Calibrated Salient Object Detection

no code implementations10 Dec 2020 Jing Zhang, Yuchao Dai, Xin Yu, Mehrtash Harandi, Nick Barnes, Richard Hartley

Existing deep neural network based salient object detection (SOD) methods mainly focus on pursuing high network accuracy.

Object object-detection +2

Refining Semantic Segmentation with Superpixel by Transparent Initialization and Sparse Encoder

1 code implementation9 Oct 2020 Zhiwei Xu, Thalaiyasingam Ajanthan, Richard Hartley

We achieve it with fully-connected layers with Transparent Initialization (TI) and efficient logit consistency using a sparse encoder.

Segmentation Semantic Segmentation +1

RANP: Resource Aware Neuron Pruning at Initialization for 3D CNNs

1 code implementation6 Oct 2020 Zhiwei Xu, Thalaiyasingam Ajanthan, Vibhav Vineet, Richard Hartley

Specifically, the core idea is to obtain an importance score for each neuron based on their sensitivity to the loss function.

3D Semantic Segmentation Video Classification

Calibration of Neural Networks using Splines

1 code implementation ICLR 2021 Kartik Gupta, Amir Rahimi, Thalaiyasingam Ajanthan, Thomas Mensink, Cristian Sminchisescu, Richard Hartley

From this, by approximating the empirical cumulative distribution using a differentiable function via splines, we obtain a recalibration function, which maps the network outputs to actual (calibrated) class assignment probabilities.

Decision Making Image Classification

Post-hoc Calibration of Neural Networks by g-Layers

no code implementations23 Jun 2020 Amir Rahimi, Thomas Mensink, Kartik Gupta, Thalaiyasingam Ajanthan, Cristian Sminchisescu, Richard Hartley

Calibration of neural networks is a critical aspect to consider when incorporating machine learning models in real-world decision-making systems where the confidence of decisions are equally important as the decisions themselves.

Decision Making Image Classification

Single Image Optical Flow Estimation with an Event Camera

no code implementations CVPR 2020 Liyuan Pan, Miaomiao Liu, Richard Hartley

Then, we consider the special case of image blur caused by high dynamics in the visual environments and show that including the blur formation in our model further constrains flow estimation.

Deblurring Image Deblurring +1

Pairwise Similarity Knowledge Transfer for Weakly Supervised Object Localization

1 code implementation ECCV 2020 Amir Rahimi, Amirreza Shaban, Thalaiyasingam Ajanthan, Richard Hartley, Byron Boots

Weakly Supervised Object Localization (WSOL) methods only require image level labels as opposed to expensive bounding box annotations required by fully supervised algorithms.

Transfer Learning Weakly-Supervised Object Localization

Intra Order-preserving Functions for Calibration of Multi-Class Neural Networks

1 code implementation NeurIPS 2020 Amir Rahimi, Amirreza Shaban, Ching-An Cheng, Richard Hartley, Byron Boots

A common approach is to learn a post-hoc calibration function that transforms the output of the original network into calibrated confidence scores while maintaining the network's accuracy.

Joint Unsupervised Learning of Optical Flow and Egomotion with Bi-Level Optimization

no code implementations26 Feb 2020 Shihao Jiang, Dylan Campbell, Miaomiao Liu, Stephen Gould, Richard Hartley

We address the problem of joint optical flow and camera motion estimation in rigid scenes by incorporating geometric constraints into an unsupervised deep learning framework.

Motion Estimation Optical Flow Estimation

Action Anticipation with RBF Kernelized Feature Mapping RNN

no code implementations ECCV 2018 Yuge Shi, Basura Fernando, Richard Hartley

We introduce a novel Recurrent Neural Network-based algorithm for future video feature generation and action anticipation called feature mapping RNN.

Action Anticipation

Fast and Differentiable Message Passing on Pairwise Markov Random Fields

1 code implementation24 Oct 2019 Zhiwei Xu, Thalaiyasingam Ajanthan, Richard Hartley

In addition to differentiability, the two main aspects that enable learning these model parameters are the forward and backward propagation time of the MRF optimization algorithm and its inference capabilities.

Denoising Semantic Segmentation

Mirror Descent View for Neural Network Quantization

1 code implementation18 Oct 2019 Thalaiyasingam Ajanthan, Kartik Gupta, Philip H. S. Torr, Richard Hartley, Puneet K. Dokania

Quantizing large Neural Networks (NN) while maintaining the performance is highly desirable for resource-limited devices due to reduced memory and time complexity.

Quantization valid

Deep Declarative Networks: A New Hope

1 code implementation11 Sep 2019 Stephen Gould, Richard Hartley, Dylan Campbell

We show how these declarative processing nodes can be implemented in the popular PyTorch deep learning software library allowing declarative and imperative nodes to co-exist within the same network.

Point Cloud Classification

Identity-preserving Face Recovery from Stylized Portraits

no code implementations7 Apr 2019 Fatemeh Shiri, Xin Yu, Fatih Porikli, Richard Hartley, Piotr Koniusz

We develop an Identity-preserving Face Recovery from Portraits (IFRP) method that utilizes a Style Removal network (SRN) and a Discriminative Network (DN).

Recovering Faces from Portraits with Auxiliary Facial Attributes

no code implementations7 Apr 2019 Fatemeh Shiri, Xin Yu, Fatih Porikli, Richard Hartley, Piotr Koniusz

%Our method can recover high-quality photorealistic faces from unaligned portraits while preserving the identity of the face images as well as it can reconstruct a photorealistic face image with a desired set of attributes.

Attribute

High Frame Rate Video Reconstruction based on an Event Camera

1 code implementation12 Mar 2019 Liyuan Pan, Richard Hartley, Cedric Scheerlinck, Miaomiao Liu, Xin Yu, Yuchao Dai

Based on the abundant event data alongside a low frame rate, easily blurred images, we propose a simple yet effective approach to reconstruct high-quality and high frame rate sharp videos.

Video Generation Video Reconstruction +1

Super-Trajectories: A Compact Yet Rich Video Representation

no code implementations22 Jan 2019 Ijaz Akhter, Cheong Loong Fah, Richard Hartley

We propose a new video representation in terms of an over-segmentation of dense trajectories covering the whole video.

Position Superpixels

Proximal Mean-field for Neural Network Quantization

1 code implementation ICCV 2019 Thalaiyasingam Ajanthan, Puneet K. Dokania, Richard Hartley, Philip H. S. Torr

Compressing large Neural Networks (NN) by quantizing the parameters, while maintaining the performance is highly desirable due to reduced memory and time complexity.

Image Classification Quantization

Bringing a Blurry Frame Alive at High Frame-Rate with an Event Camera

1 code implementation CVPR 2019 Liyuan Pan, Cedric Scheerlinck, Xin Yu, Richard Hartley, Miaomiao Liu, Yuchao Dai

In this paper, we propose a simple and effective approach, the \textbf{Event-based Double Integral (EDI)} model, to reconstruct a high frame-rate, sharp video from a single blurry frame and its event data.

Video Generation

Generalized Range Moves

no code implementations22 Nov 2018 Richard Hartley, Thalaiyasingam Ajanthan

We consider move-making algorithms for energy minimization of multi-label Markov Random Fields (MRFs).

Scalable Deep $k$-Subspace Clustering

no code implementations2 Nov 2018 Tong Zhang, Pan Ji, Mehrtash Harandi, Richard Hartley, Ian Reid

In this paper, we introduce a method that simultaneously learns an embedding space along subspaces within it to minimize a notion of reconstruction error, thus addressing the problem of subspace clustering in an end-to-end learning paradigm.

Clustering

Face Super-resolution Guided by Facial Component Heatmaps

no code implementations ECCV 2018 Xin Yu, Basura Fernando, Bernard Ghanem, Fatih Porikli, Richard Hartley

State-of-the-art face super-resolution methods use deep convolutional neural networks to learn a mapping between low-resolution (LR) facial patterns and their corresponding high-resolution (HR) counterparts by exploring local information.

Face Hallucination Hallucination +1

Super-Resolving Very Low-Resolution Face Images With Supplementary Attributes

no code implementations CVPR 2018 Xin Yu, Basura Fernando, Richard Hartley, Fatih Porikli

An LR input contains low-frequency facial components of its HR version while its residual face image defined as the difference between the HR ground-truth and interpolated LR images contains the missing high-frequency facial details.

Attribute Face Hallucination +2

Block Mean Approximation for Efficient Second Order Optimization

no code implementations16 Apr 2018 Yao Lu, Mehrtash Harandi, Richard Hartley, Razvan Pascanu

Advanced optimization algorithms such as Newton method and AdaGrad benefit from second order derivative or second order statistics to achieve better descent directions and faster convergence rates.

Non-Linear Temporal Subspace Representations for Activity Recognition

no code implementations CVPR 2018 Anoop Cherian, Suvrit Sra, Stephen Gould, Richard Hartley

As these features are often non-linear, we propose a novel pooling method, kernelized rank pooling, that represents a given sequence compactly as the pre-image of the parameters of a hyperplane in a reproducing kernel Hilbert space, projections of data onto which captures their temporal order.

Action Recognition Riemannian optimization +3

Identity-preserving Face Recovery from Portraits

no code implementations8 Jan 2018 Fatemeh Shiri, Xin Yu, Fatih Porikli, Richard Hartley, Piotr Koniusz

In this paper, we present a new Identity-preserving Face Recovery from Portraits (IFRP) to recover latent photorealistic faces from unaligned stylized portraits.

Sequence Summarization Using Order-constrained Kernelized Feature Subspaces

no code implementations24 May 2017 Anoop Cherian, Suvrit Sra, Richard Hartley

As these features are often non-linear, we propose a novel pooling method, kernelized rank pooling, that represents a given sequence compactly as the pre-image of the parameters of a hyperplane in an RKHS, projections of data onto which captures their temporal order.

Action Recognition Riemannian optimization +3

Memory Efficient Max Flow for Multi-label Submodular MRFs

1 code implementation CVPR 2016 Thalaiyasingam Ajanthan, Richard Hartley, Mathieu Salzmann

Multi-label submodular Markov Random Fields (MRFs) have been shown to be solvable using max-flow based on an encoding of the labels proposed by Ishikawa, in which each variable $X_i$ is represented by $\ell$ nodes (where $\ell$ is the number of labels) arranged in a column.

Dimensionality Reduction on SPD Manifolds: The Emergence of Geometry-Aware Methods

no code implementations20 May 2016 Mehrtash Harandi, Mathieu Salzmann, Richard Hartley

This lets us formulate dimensionality reduction as the problem of finding a projection that yields a low-dimensional manifold either with maximum discriminative power in the supervised scenario, or with maximum variance of the data in the unsupervised one.

Dimensionality Reduction

A Linear Least-Squares Solution to Elastic Shape-From-Template

no code implementations CVPR 2015 Abed Malti, Adrien Bartoli, Richard Hartley

We cast SfT (Shape-from-Template) as the search of a vector field (X, dX), composed of the pose X and the displacement dX that produces the deformation.

Position

Optimizing Over Radial Kernels on Compact Manifolds

no code implementations CVPR 2014 Sadeep Jayasumana, Richard Hartley, Mathieu Salzmann, Hongdong Li, Mehrtash Harandi

We tackle the problem of optimizing over all possible positive definite radial kernels on Riemannian manifolds for classification.

General Classification

Kernel Methods on the Riemannian Manifold of Symmetric Positive Definite Matrices

no code implementations CVPR 2013 Sadeep Jayasumana, Richard Hartley, Mathieu Salzmann, Hongdong Li, Mehrtash Harandi

To encode the geometry of the manifold in the mapping, we introduce a family of provably positive definite kernels on the Riemannian manifold of SPD matrices.

Motion Segmentation Pedestrian Detection +2

Kernel Methods on Riemannian Manifolds with Gaussian RBF Kernels

no code implementations30 Nov 2014 Sadeep Jayasumana, Richard Hartley, Mathieu Salzmann, Hongdong Li, Mehrtash Harandi

We then use the proposed framework to identify positive definite kernels on two specific manifolds commonly encountered in computer vision: the Riemannian manifold of symmetric positive definite matrices and the Grassmann manifold, i. e., the Riemannian manifold of linear subspaces of a Euclidean space.

Iteratively Reweighted Graph Cut for Multi-label MRFs with Non-convex Priors

no code implementations CVPR 2015 Thalaiyasingam Ajanthan, Richard Hartley, Mathieu Salzmann, Hongdong Li

While widely acknowledged as highly effective in computer vision, multi-label MRFs with non-convex priors are difficult to optimize.

Sparse Coding on Symmetric Positive Definite Manifolds using Bregman Divergences

no code implementations30 Aug 2014 Mehrtash Harandi, Richard Hartley, Brian Lovell, Conrad Sanderson

This paper introduces sparse coding and dictionary learning for Symmetric Positive Definite (SPD) matrices, which are often used in machine learning, computer vision and related areas.

Action Recognition Dictionary Learning +4

Expanding the Family of Grassmannian Kernels: An Embedding Perspective

no code implementations4 Jul 2014 Mehrtash T. Harandi, Mathieu Salzmann, Sadeep Jayasumana, Richard Hartley, Hongdong Li

Modeling videos and image-sets as linear subspaces has proven beneficial for many visual recognition tasks.

Clustering

From Manifold to Manifold: Geometry-Aware Dimensionality Reduction for SPD Matrices

no code implementations4 Jul 2014 Mehrtash T. Harandi, Mathieu Salzmann, Richard Hartley

In particular, we search for a projection that yields a low-dimensional manifold with maximum discriminative power encoded via an affinity-weighted similarity measure based on metrics on the manifold.

Dimensionality Reduction

On Projective Reconstruction In Arbitrary Dimensions

no code implementations CVPR 2014 Behrooz Nasihatkon, Richard Hartley, Jochen Trumpf

The current theory, due to Hartley and Schaffalitzky, is based on the Grassmann tensor, generalizing the ideas of fundamental matrix, trifocal tensor and quadrifocal tensor used in the well-studied case of 3D to 2D projections.

Extrinsic Methods for Coding and Dictionary Learning on Grassmann Manifolds

no code implementations31 Jan 2014 Mehrtash Harandi, Richard Hartley, Chunhua Shen, Brian Lovell, Conrad Sanderson

With the aim of building a bridge between the two realms, we address the problem of sparse coding and dictionary learning over the space of linear subspaces, which form Riemannian structures known as Grassmann manifolds.

Action Recognition Classification +6

Mirror Surface Reconstruction from a Single Image

no code implementations CVPR 2013 Miaomiao Liu, Richard Hartley, Mathieu Salzmann

In such conditions, our differential geometry analysis provides a theoretical proof that the shape of the mirror surface can be uniquely recovered if the pose of the reference target is known.

Surface Reconstruction

Sparse Coding and Dictionary Learning for Symmetric Positive Definite Matrices: A Kernel Approach

1 code implementation16 Apr 2013 Mehrtash T. Harandi, Conrad Sanderson, Richard Hartley, Brian C. Lovell

Recent advances suggest that a wide range of computer vision problems can be addressed more appropriately by considering non-Euclidean geometry.

Dictionary Learning Face Recognition +3

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