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Irfan Essa

35 accepted papers

2026

MapReduce LoRA: Advancing the Pareto Front in Multi-Preference Optimization for Generative Models

CVPR 2026

Reinforcement learning from human feedback (RLHF) with reward models has advanced alignment of generative models to human aesthetic and perceptual preferences. However, jointly optimizing multiple rewards often incurs an alignment tax--improving one dimension while degrading others. To address this,

Cited by 0SourcecodeScholar
2025

AfriMed-QA: A Pan-African, Multi-Specialty, Medical Question-Answering Benchmark Dataset

ACL 2025long

Recent advancements in large language model (LLM) performance on medical multiplechoice question (MCQ) benchmarks have stimulated interest from healthcare providers and patients globally. Particularly in low-andmiddle-income countries (LMICs) facing acute physician shortages and lack of specialists,…

Cited by 0SourcePDFScholar
2025

Africa Health Check: Probing Cultural Bias in Medical LLMs

EMNLP 2025

Large language models (LLMs) are increasingly deployed in global healthcare, yet their outputs often reflect Western-centric training data and omit indigenous medical systems and region-specific treatments. This study investigates cultural bias in instruction-tuned medical LLMs using a curated datas

2025

Calibrated Multi-Preference Optimization for Aligning Diffusion Models

CVPR 2025poster

Aligning text-to-image (T2I) diffusion models with prefer-ence optimization is valuable for human-annotated datasets, but the heavy cost of manual data collection limits scalability. Using reward models offers an alternative, however, current preference optimization methods fall short in exploiting…

Cited by 5SourcePDFScholar
2025

Cropper: Vision-Language Model for Image Cropping through In-Context Learning

CVPR 2025poster

The goal of image cropping is to identify visually appealing crops in an image. Conventional methods are trained on specific datasets and fail to adapt to new requirements. Recent breakthroughs in large vision-language models (VLMs) enable visual in-context learning without explicit training. Howeve…

Cited by 2SourcePDFScholar
2025

Limitations in Employing Natural Language Supervision for Sensor-Based Human Activity Recognition - And Ways to Overcome Them

AAAI 2025technical

Cross-modal contrastive pre-training between natural language and other modalities, e.g., vision and audio, has demonstrated astonishing performance and effectiveness across a diverse variety of tasks and domains. In this paper, we investigate whether such natural language supervision can be used fo…

Cited by 2SourcePDFScholar
2024

BayRnTune: Adaptive Bayesian Domain Randomization via Strategic Fine-tuning

IROS 2024poster

Domain randomization (DR), which entails training a policy with randomized dynamics, has proven to be a simple yet effective algorithm for reducing the gap between simulation and the real world. However, DR often requires careful tuning of randomization parameters. Methods like Bayesian Domain Rando…

Cited by 3SourceScholar
2024

FineStyle: Fine-grained Controllable Style Personalization for Text-to-image Models

NeurIPS 2024poster

Few-shot fine-tuning of text-to-image (T2I) generation models enables people to create unique images in their own style using natural languages without requiring extensive prompt engineering. However, fine-tuning with only a handful, as little as one, of image-text paired data prevents fine-grained…

Cited by 4SourcePDFScholar
2024

Language Model Beats Diffusion - Tokenizer is key to visual generation

ICLR 2024poster

While Large Language Models (LLMs) are the dominant models for generative tasks in language, they do not perform as well as diffusion models on image and video generation. To effectively use LLMs for visual generation, one crucial component is the visual tokenizer that maps pixel-space inputs to dis…

Cited by 296SourcePDFScholar
2024

Parrot: Pareto-optimal Multi-Reward Reinforcement Learning Framework for Text-to-Image Generation

ECCV 2024oral

"Recent works have demonstrated that using reinforcement learning (RL) with multiple quality rewards can improve the quality of generated images in text-to-image (T2I) generation. However, manually adjusting reward weights poses challenges and may cause over-optimization in certain metrics. To solve…

Cited by 22SourcePDFScholar
2024

Photorealistic Video Generation with Diffusion Models

ECCV 2024poster

"We present , a diffusion transformer for photorealistic video generation from text prompts. Our approach has two key design decisions. First, we use a causal encoder to jointly compress images and videos within a unified latent space, enabling training and generation across modalities. Second, for…

Cited by 188SourcePDFScholar
2024

Prompt-Free Diffusion: Taking "Text" out of Text-to-Image Diffusion Models

CVPR 2024poster

Text-to-image (T2I) research has grown explosively in the past year owing to the large-scale pre-trained diffusion models and many emerging personalization and editing approaches. Yet one pain point persists: the text prompt engineering and searching high-quality text prompts for customized results…

2024

VideoPoet: A Large Language Model for Zero-Shot Video Generation

ICML 2024oral

We present VideoPoet, a language model capable of synthesizing high-quality video from a large variety of conditioning signals. VideoPoet employs a decoder-only transformer architecture that processes multimodal inputs -- including images, videos, text, and audio. The training protocol follows that…

Cited by 257SourcePDFScholar
2023

Discrete Predictor-Corrector Diffusion Models for Image Synthesis

ICLR 2023poster

We introduce Discrete Predictor-Corrector diffusion models (DPC), extending predictor-corrector samplers in Gaussian diffusion models to the discrete case. Predictor-corrector samplers are a class of samplers for diffusion models, which improve on ancestral samplers by correcting the sampling distri…

Cited by 18SourcePDFScholar
2023

Emergence of Maps in the Memories of Blind Navigation Agents

ICLR 2023top-5%

Animal navigation research posits that organisms build and maintain internal spa- tial representations, or maps, of their environment. We ask if machines – specifically, artificial intelligence (AI) navigation agents – also build implicit (or ‘mental’) maps. A positive answer to this question would…

Cited by 31SourcePDFScholar
2023

MAGVIT: Masked Generative Video Transformer

CVPR 2023highlight

We introduce the MAsked Generative VIdeo Transformer, MAGVIT, to tackle various video synthesis tasks with a single model. We introduce a 3D tokenizer to quantize a video into spatial-temporal visual tokens and propose an embedding method for masked video token modeling to facilitate multi-task lear…

2023

MaskSketch: Unpaired Structure-Guided Masked Image Generation

CVPR 2023highlight

Recent conditional image generation methods produce images of remarkable diversity, fidelity and realism. However, the majority of these methods allow conditioning only on labels or text prompts, which limits their level of control over the generation result. In this paper, we introduce MaskSketch,…

2023

SPAE: Semantic Pyramid AutoEncoder for Multimodal Generation with Frozen LLMs

NeurIPS 2023spotlight

In this work, we introduce Semantic Pyramid AutoEncoder (SPAE) for enabling frozen LLMs to perform both understanding and generation tasks involving non-linguistic modalities such as images or videos. SPAE converts between raw pixels and interpretable lexical tokens (or words) extracted from the LLM…

Cited by 59SourcePDFScholar
2023

StyleDrop: Text-to-Image Synthesis of Any Style

NeurIPS 2023poster

Pre-trained large text-to-image models synthesize impressive images with an appropriate use of text prompts. However, ambiguities inherent in natural language, and out-of-distribution effects make it hard to synthesize arbitrary image styles, leveraging a specific design pattern, texture or material…

2023

Visual Prompt Tuning for Generative Transfer Learning

CVPR 2023poster

Learning generative image models from various domains efficiently needs transferring knowledge from an image synthesis model trained on a large dataset. We present a recipe for learning vision transformers by generative knowledge transfer. We base our framework on generative vision transformers repr…

2022

BLT: Bidirectional Layout Transformer for Controllable Layout Generation

ECCV 2022poster

"Creating visual layouts is a critical step in graphic design. Automatic generation of such layouts is essential for scalable and diverse visual designs. To advance conditional layout generation, we introduce BLT, a bidirectional layout transformer. BLT differs from previous work on transformers in…

2022

Discrete Representations Strengthen Vision Transformer Robustness

ICLR 2022poster

Vision Transformer (ViT) is emerging as the state-of-the-art architecture for image recognition. While recent studies suggest that ViTs are more robust than their convolutional counterparts, our experiments find that ViTs are overly reliant on local features (\eg, nuisances and texture) and fail to…

Cited by 54SourcePDFScholar
2022

Graph-based Cluttered Scene Generation and Interactive Exploration using Deep Reinforcement Learning

ICRA 2022poster

We introduce a novel method to teach a robotic agent to interactively explore cluttered yet structured scenes, such as kitchen pantries and grocery shelves, by leveraging the physical plausibility of the scene. We propose a novel learning framework to train an effective scene exploration policy to d…

Cited by 17SourceScholar
2022

VER: Scaling On-Policy RL Leads to the Emergence of Navigation in Embodied Rearrangement

NeurIPS 2022accept

We present Variable Experience Rollout (VER), a technique for efficiently scaling batched on-policy reinforcement learning in heterogenous environments (where different environments take vastly different times to generate rollouts) to many GPUs residing on, potentially, many machines. VER combines t…

2021

Semantic MapNet: Building Allocentric Semantic Maps and Representations from Egocentric Views

AAAI 2021technical

We study the task of semantic mapping – specifically, an embodied agent (a robot or an egocentric AI assistant) is given a tour of a new environment and asked to build an allocentric top-down semantic map (‘what is where?’) from egocentric observations of an RGB-D camera with known pose (via localiz…

2020

DD-PPO: Learning Near-Perfect PointGoal Navigators from 2.5 Billion Frames

ICLR 2020poster

We present Decentralized Distributed Proximal Policy Optimization (DD-PPO), a method for distributed reinforcement learning in resource-intensive simulated environments. DD-PPO is distributed (uses multiple machines), decentralized (lacks a centralized server), and synchronous (no computation is eve…

Cited by 542SourcecodeScholar
2020

Neural Design Network: Graphic Layout Generation with Constraints

ECCV 2020poster

Graphic design is essential for visual communication with layouts being fundamental to composing attractive designs. Layout generation differs from pixel-level image synthesis and is unique in terms of the requirement of mutual relations among the desired components. We propose a method for design l…

Cited by 152SourcePDFScholar
2019

A Data-Driven Predictive Model of Individual-Specific Effects of FES on Human Gait Dynamics

ICRA 2019poster

Modeling individual-specific gait dynamics based on kinematic data could aid development of gait rehabilitation robotics by enabling robots to predict the user's gait kinematics with and without external inputs, such as mechanical or electrical perturbations. Here we address a current limitation of…

Cited by 4SourceScholar
2019

Audio Visual Scene-Aware Dialog

CVPR 2019poster

We introduce the task of scene-aware dialog. Our goal is to generate a complete and natural response to a question about a scene, given video and audio of the scene and the history of previous turns in the dialog. To answer successfully, agents must ground concepts from the question in the video whi…

Cited by 226PDFcodeScholar
2019

Embodied Question Answering in Photorealistic Environments With Point Cloud Perception

CVPR 2019oral

To help bridge the gap between internet vision-style problems and the goal of vision for embodied perception we instantiate a large-scale navigation task -- Embodied Question Answering [1] in photo-realistic environments (Matterport 3D). We thoroughly study navigation policies that utilize 3D poin…

Cited by 193PDFScholar
2019

End-to-end Audio Visual Scene-aware Dialog Using Multimodal Attention-based Video Features

ICASSP 2019accepted

In order for machines interacting with the real world to have conversations with users about the objects and events around them, they need to understand dynamic audiovisual scenes. The recent revolution of neural network models allows us to combine various modules into a single end-to-end differenti…

Cited by 0SourceScholar