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Violetta Shevchenko

dblp:231/1762 · DBLP profile ↗
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8ranked-venue papers
1as first author
7since 2021 · last 2025
—ORCID · none

Domains — the database's venue-derived domains; a paper can count in several

Artificial intelligence and machine learning · 8 · 1 first-author · 7 since 2021Graphics, computer vision, multimedia, augmented reality and games · 3 · 1 first-author · 2 since 2021

Expertise — from the expertise taxonomy: the topics of the expert's papers under the CCF categories. A weight counts papers with recency: 1 for a paper about the topic, 0.3 when the topic is its context, halved every five years.

Artificial intelligence
4 papers
3D vision · 32% Efficient and distributed learning · 27% Representation and self-supervised learning · 16%
Computer graphics and multimedia
3 papers
Image and video processing · 48% Visual content generation and editing · 24% Geometric modeling and processing · 21%
Theoretical computer science
2 papers
Information theory · 77% Mathematical optimization · 23%

Topics — the 18 heaviest of 19, each with the papers that count most for it

TopicWeightPapersLastEvidence papers
Computer vision › 3D vision
neural radiance field
1.522024
Improving the Convergence of Dynamic NeRFs via Optimal Transport · ICLR 2024
BLiRF: Bandlimited Radiance Fields for Dynamic Scene Modeling · AAAI 2024
Machine learning › Efficient and distributed learning › model compression › neural network compression
activation compression
0.912025
Mixtures of Subspaces for Bandwidth Efficient Context Parallel Training · NeurIPS 2025
Machine learning › Efficient and distributed learning › distributed training
communication-efficient training
0.912025
Mixtures of Subspaces for Bandwidth Efficient Context Parallel Training · NeurIPS 2025
Machine learning › Efficient and distributed learning
distributed training
0.912025
Mixtures of Subspaces for Bandwidth Efficient Context Parallel Training · NeurIPS 2025
Natural language and speech › Language models and text generation › language modeling
long-context language modeling
0.912025
Mixtures of Subspaces for Bandwidth Efficient Context Parallel Training · NeurIPS 2025
Image and video processing › super-resolution › image super-resolution › generative image super-resolution
diffusion-based super-resolution
0.912025
SRSR: Enhancing Semantic Accuracy in Real-World Image Super-Resolution with Spatially Re-Focused Text-Conditioning · NeurIPS 2025
Image and video processing
super-resolution
0.912025
SRSR: Enhancing Semantic Accuracy in Real-World Image Super-Resolution with Spatially Re-Focused Text-Conditioning · NeurIPS 2025
Visual content generation and editing
visual text generation
0.912025
SRSR: Enhancing Semantic Accuracy in Real-World Image Super-Resolution with Spatially Re-Focused Text-Conditioning · NeurIPS 2025
Computer vision › Vision and language
cross-modal retrieval
0.812024
Accept the Modality Gap: An Exploration in the Hyperbolic Space · CVPR 2024
Computer vision › 3D vision › 3d scene modeling › scene representation
dynamic scene modeling
0.812024
BLiRF: Bandlimited Radiance Fields for Dynamic Scene Modeling · AAAI 2024
Machine learning › Representation and self-supervised learning › representation learning › dimensionality reduction › manifold learning › geometric representation learning
hyperbolic representation learning
0.812024
Accept the Modality Gap: An Exploration in the Hyperbolic Space · CVPR 2024
Machine learning › Representation and self-supervised learning
multimodal representation learning
0.812024
Accept the Modality Gap: An Exploration in the Hyperbolic Space · CVPR 2024
Computer vision › 3D vision
novel view synthesis
0.812024
BLiRF: Bandlimited Radiance Fields for Dynamic Scene Modeling · AAAI 2024
Computer vision › Video understanding and tracking › motion analysis
scene dynamics
0.812024
BLiRF: Bandlimited Radiance Fields for Dynamic Scene Modeling · AAAI 2024
Geometric modeling and processing
implicit neural representation
0.812024
A sampling theory perspective on activations for implicit neural representations · ICML 2024
Information theory › signal processing
sampling theory
0.812024
A sampling theory perspective on activations for implicit neural representations · ICML 2024
Computer animation and physical simulation
motion modeling
0.212024
BLiRF: Bandlimited Radiance Fields for Dynamic Scene Modeling · AAAI 2024
Mathematical optimization
optimal transport
0.212024
Improving the Convergence of Dynamic NeRFs via Optimal Transport · ICLR 2024

Methods — techniques the papers use, named apart from their topics

sampling theory · 1.5optimal transport · 1.5implicit neural representation · 1.5geometric regularization · 1.5dynamical systems analysis · 1.5bandlimited signal factorization · 1.5segmentation masks · 0.9mixtures of subspaces · 0.9low-rank reparameterization · 0.9cross-attention · 0.9classifier-free guidance · 0.9geodesic distance · 0.8contrastive learning · 0.8
YearPublicationVenuePosition
2025 SRSR: Enhancing Semantic Accuracy in Real-World Image Super-Resolution with Spatially Re-Focused Text-Conditioning
abstract
Existing diffusion-based super-resolution approaches often exhibit semantic ambiguities due to inaccuracies and incompleteness in their text conditioning, coupled with the inherent tendency for cross-attention to divert towards irrelevant pixels. These limitations can lead to semantic misalignment and hallucinated details in the generated high-resolution outputs. To address these, we propose a novel, plug-and-play *spatially re-focused super-resolution (SRSR)* framework that consists of two core components: first, we introduce Spatially Re-focused Cross-Attention (SRCA), which refines text conditioning at inference time by applying visually-grounded segmentation masks to guide cross-attention. Second, we introduce a Spatially Targeted Classifier-Free Guidance (STCFG) mechanism that selectively bypasses text influences on ungrounded pixels to prevent hallucinations. Extensive experiments on both synthetic and real-world datasets demonstrate that SRSR consistently outperforms seven state-of-the-art baselines in standard fidelity metrics (PSNR and SSIM) across all datasets, and in perceptual quality measures (LPIPS and DISTS) on two real-world benchmarks, underscoring its effectiveness in achieving both high semantic fidelity and perceptual quality in super-resolution.
Majid Abdolshah, Violetta Shevchenko, Hongdong Li, Pulak Purkait
NeurIPS3
2025 Unextractable Protocol Models: Collaborative Training and Inference without Weight Materialization
abstract
We consider a decentralized setup in which the participants collaboratively train and serve a large neural network, and where each participant only processes a subset of the model. In this setup, we explore the possibility of unmaterializable weights, where a full weight set is never available to any one participant. We introduce Unextractable Protocol Models (UPMs): a training and inference framework that leverages the sharded model setup to ensure model shards (i.e.,, subsets) held by participants are incompatible at different time steps. UPMs periodically inject time-varying, random, invertible transforms at participant boundaries; preserving the overall network function yet rendering cross-time assemblies incoherent. On Qwen-2.5-0.5B and Llama-3.2-1B, 10 000 transforms leave FP32 perplexity unchanged ($\Delta$PPL$< 0.01$; Jensen–Shannon drift $<4 \times 10^{-5}$), and we show how to control growth for lower precision datatypes. Applying a transform every 30s adds 3% latency, 0.1% bandwidth, and 10% GPU-memory overhead at inference, while training overhead falls to 1.6% time and < 1% memory. We consider several attacks, showing that the requirements of direct attacks are impractical and easy to defend against, and that gradient-based fine-tuning of stitched partitions consumes $\geq 60\%$ of the tokens required to train from scratch. By enabling models to be collaboratively trained yet not extracted, UPMs make it practical to embed programmatic incentive mechanisms in community-driven decentralized training.
Alexander Long, Chamin Hewa Koneputugodage, Thalaiyasingam Ajanthan, Gil Avraham, Violetta Shevchenko, Hadi M. Dolatabadi, Sameera Ramasinghe
NeurIPS6
2025 Mixtures of Subspaces for Bandwidth Efficient Context Parallel Training
abstract
Pretraining language models with extended context windows enhances their ability to leverage rich information during generation. Existing methods split input sequences into chunks, broadcast them across multiple devices, and compute attention block by block which incurs significant communication overhead. While feasible in high-speed clusters, these methods are impractical for decentralized training over low-bandwidth connections. We propose a compression method for communication-efficient context parallelism in decentralized settings, achieving a remarkable compression rate of over 95% with negligible overhead and no loss in convergence. Our key insight is to exploit the intrinsic low-rank structure of activation outputs by dynamically constraining them to learned mixtures of subspaces via efficient reparameterizations. We demonstrate scaling billion-parameter decentralized models to context lengths exceeding 100K tokens on networks as slow as 300Mbps, matching the wall-clock convergence speed of centralized models on 100Gbps interconnects.
Sameera Ramasinghe, Thalaiyasingam Ajanthan, Hadi M. Dolatabadi, Gil Avraham, Violetta Shevchenko, Chamin Hewa Koneputugodage, Alexander Long
NeurIPS5
2024 BLiRF: Bandlimited Radiance Fields for Dynamic Scene Modeling
abstract
Inferring the 3D structure of a non-rigid dynamic scene from a single moving camera is an under-constrained problem. Inspired by the remarkable progress of neural radiance fields (NeRFs) in photo-realistic novel view synthesis of static scenes, it has also been extended to dynamic settings. Such methods heavily rely on implicit neural priors to regularize the problem. In this work, we take a step back and investigate how current implementations may entail deleterious effects including limited expressiveness, entanglement of light and density fields, and sub-optimal motion localization. Further, we devise a factorisation-based framework that represents the scene as a composition of bandlimited, high-dimensional signals. We demonstrate compelling results across complex dynamic scenes that involve changes in lighting, texture and long-range dynamics.
Sameera Ramasinghe, Violetta Shevchenko, Gil Avraham, Anton van den Hengel
AAAI2
2024 Accept the Modality Gap: An Exploration in the Hyperbolic Space
abstract
Recent advancements in machine learning have spotlighted the potential of hyperbolic spaces as they effectively learn hierarchical feature representations. While there has been progress in leveraging hyperbolic spaces in single-modality contexts, its exploration in multimodal settings remains under explored. A recent work has sought to transpose Euclidean multimodal learning techniques to hyperbolic spaces, by adopting a geodesic distance based contrastive loss. However, we show both theoretically and empirically that such spatial proximity based contrastive loss significantly disrupts hierarchies in the latent space. To remedy this, we advocate that the cross-modal representations should accept the inherent modality gap between text and images, and introduce a novel approach to measure cross-modal similarity that does not enforce spatial proximity. Our approach shows remarkable capabilities in preserving unimodal hierarchies while aligning the two modalities. Our experiments on a series of downstream tasks demonstrate that a better latent structure emerges with our objective function while being superior in text-to-image and image-to-text retrieval tasks.
Sameera Ramasinghe, Violetta Shevchenko, Gil Avraham, Thalaiyasingam Ajanthan
CVPR2
2024 Improving the Convergence of Dynamic NeRFs via Optimal Transport
abstract
Synthesizing novel views for dynamic scenes from a collection of RGB inputs poses significant challenges due to the inherent under-constrained nature of the problem. To mitigate this ill-posedness, practitioners in the field of neural radiance fields (NeRF) often resort to the adoption of intricate geometric regularization techniques, including scene flow, depth estimation, or learned perceptual similarity. While these geometric cues have demonstrated their effectiveness, their incorporation leads to evaluation of computationally expensive off-the-shelf models, introducing substantial computational overhead into the pipeline. Moreover, seamlessly integrating such modules into diverse dynamic NeRF models can be a non-trivial task, hindering their utilization in an architecture-agnostic manner. In this paper, we propose a theoretically grounded, lightweight regularizer by treating the dynamics of a time-varying scene as a low-frequency change of a probability distribution of the light intensity. We constrain the dynamics of this distribution using optimal transport (OT) and provide error bounds under reasonable assumptions. Our regularization is learning-free, architecture agnostic, and can be implemented with just a few lines of code. Finally, we demonstrate the practical efficacy of our regularizer across state-of-the-art architectures.
Sameera Ramasinghe, Violetta Shevchenko, Gil Avraham, Hisham Husain, Anton van den Hengel
ICLR2
2024 A sampling theory perspective on activations for implicit neural representations
abstract
Implicit Neural Representations (INRs) have gained popularity for encoding signals as compact, differentiable entities. While commonly using techniques like Fourier positional encodings or non-traditional activation functions (e.g., Gaussian, sinusoid, or wavelets) to capture high-frequency content, their properties lack exploration within a unified theoretical framework. Addressing this gap, we conduct a comprehensive analysis of these activations from a sampling theory perspective. Our investigation reveals that, especially in shallow INRs, $\mathrm{sinc}$ activations—previously unused in conjunction with INRs—are theoretically optimal for signal encoding. Additionally, we establish a connection between dynamical systems and INRs, leveraging sampling theory to bridge these two paradigms.
Hemanth Saratchandran, Sameera Ramasinghe, Violetta Shevchenko, Alexander Long, Simon Lucey
ICML3
2018 Fish Detection from Low Visibility Underwater Videos
abstract
Counting and tracking fish populations is important for conservation purposes as well as for the fishing industry. Various non-invasive automatic fish counters exist based on such principles as resistivity, light beams and sonar. However, such methods typically cannot make distinction between fish and other passing objects, and moreover, cannot recognize different species. Computer vision techniques provide an attractive alternative for building a more robust and versatile fish counting systems. In this paper we present the fish detection framework for noisy videos captured in water with low visibility. For this purpose, we compare three background subtraction methods for the task. Moreover, we propose necessary post-processing steps and heuristics to detect the fish and separate them from other moving objects. The results showed that by choosing an appropriate background subtraction method, it is possible to achieve a satisfying detection accuracy of 80% and 60% for two challenging datasets. The proposed method will form a basis for the future development of fish species identification methods.
Violetta Shevchenko, Tuomas Eerola, Arto Kaarna
ICPR1