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Ira Ktena

7 accepted papers

2026

Dynamic Classifier-Free Diffusion Guidance via Online Feedback

ICLR 2026poster

Classifier-free guidance (CFG) is a cornerstone of text-to-image diffusion models, yet its effectiveness is limited by the use of static guidance scales. This ``one-size-fits-all'' approach fails to adapt to the diverse requirements of different prompts; moreover, prior solutions like gradient-based…

Cited by 0SourceScholar
2025

FunBO: Discovering Acquisition Functions for Bayesian Optimization with FunSearch

ICML 2025poster

The sample efficiency of Bayesian optimization algorithms depends on carefully crafted acquisition functions (AFs) guiding the sequential collection of function evaluations. The best-performing AFs can vary significantly across optimization problems, often requiring ad-hoc and problem-specific choic…

Cited by 5SourcePDFScholar
2025

Revisiting text-to-image evaluation with Gecko: on metrics, prompts, and human rating

ICLR 2025spotlight

While text-to-image (T2I) generative models have become ubiquitous, they do not necessarily generate images that align with a given prompt. While many metrics and benchmarks have been proposed to evaluate T2I models and alignment metrics, the impact of the evaluation components (prompt sets, human…

Cited by 12SourcePDFScholar
2025

SciVid: Cross-Domain Evaluation of Video Models in Scientific Applications

ICCV 2025poster

In recent years, there has been a proliferation of spatiotemporal foundation models in different scientific disciplines. While promising, these models are often domain-specific and are only assessed within the particular applications for which they are designed. Given that many tasks can be represen…

2023

Affinity-Aware Graph Networks

NeurIPS 2023poster

Graph Neural Networks (GNNs) have emerged as a powerful technique for learning on relational data. Owing to the relatively limited number of message passing steps they perform—and hence a smaller receptive field—there has been significant interest in improving their expressivity by incorporating str…

Cited by 22SourcePDFScholar
2022

A Fine-Grained Analysis on Distribution Shift

ICLR 2022oral

Robustness to distribution shifts is critical for deploying machine learning models in the real world. Despite this necessity, there has been little work in defining the underlying mechanisms that cause these shifts and evaluating the robustness of algorithms across multiple, different distribution…