Year wise list:   2022 | 2020 | 2018 | 2017 | 2016 | 2015 | 2014 | 2013 |

Automatically Generating Audio Descriptions for Movies

Professor Andrew Zisserman

Date : 21/08/2023

Abstract:

Audio Description is the task of generating descriptions of visual content, at suitable time intervals, for the benefit of visually impaired audiences. For movies, this presents notable challenges - the Audio Description must occur only during existing pauses in dialogue, should refer to characters by name, and ought to aid understanding of the storyline as a whole. This requires a visual-language model that can address all three of the `what', `who', and `when' questions: What is happening in the scene? Who are the characters in the scene? And when should a description be given?

Professor Andrew Zisserman visited IIIT-H and gave a talk on the 21st of August, 2023. He discussed how to build on large pre-trained models to construct a visual-language model that can generate Audio Descriptions addressing the following questions: (i) how to incorporate visual information into a pre-trained language model; (ii) how to train the model using only partial information; (iii) how to use a `character bank' to provide information on who is in a scene; and (iv) how to improve the temporal alignment of an ASR model to obtain clean data for training.

Towards Trustworthy and Fair Medical Image Analysis Models

Raghav Mehta

Date : 15/05/2023

Abstract:

Although Deep Learning (DL) models have been shown to perform very well on various medical imaging tasks, inference in the presence of pathology presents several challenges to common models. These challenges impede the integration of DL models into real clinical workflows. Deployment of these models into real clinical contexts requires: (1) that the confidence in DL model predictions be accurately expressed in the form of uncertainties and (2) that they exhibit robustness and fairness across different sub-populations. In this talk, we will look at our recent work, where we developed an uncertainty quantification score for the task of Brain Tumour Segmentation. We evaluated the score's usefulness during the two consecutive Brain Tumour Segmentation (BraTS) challenges, BraTS 2019 and BraTS 2020. Overall, our findings confirm the importance and complementary value that uncertainty estimates provide to segmentation algorithms, highlighting the need for uncertainty quantification in medical image analyses. Additionally, we combine the aspect of uncertainty estimates with fairness across demographic subgroups into the picture. By performing extensive experiments on multiple tasks, we show that popular ML methods for achieving fairness across different subgroups, such as data-balancing and distributionally robust optimization, succeed in terms of the model performances for some of the tasks. However, this can come at the cost of poor uncertainty estimates associated with the model predictions. At last, we talk about our ongoing work on fairness mitigation framework in terms of calibration. Although several methods have been shown to successfully mitigate biases across subgroups in terms of accuracy, they do not consider calibration across different subgroups of these models. To this end, we propose a novel two-stage method Cluster-Focal. Extensive experiments on two different medical image classification datasets show that our method effectively controls calibration error in the worst-performing subgroups while preserving prediction performance, outperforming recent baselines.

Computer vision - Self-Supervised Representation Learning

Yash Patel

Date : 16/03/2023

Abstract:

Yash Patel during his presentation, discussed a range of topics related to his research interests, which primarily include Self-Supervised Representation Learning, Image Compression, Scene Text Detection and Recognition, Tracking and Segmentation in Videos, and 3D Reconstruction.
Specifically, he discussed the challenges associated with Training Neural Networks on Non-Differentiable Losses and presented various approaches for overcoming these challenges. In particular, he presented his proposed technique for training a neural network by minimizing a surrogate loss that approximates a target evaluation metric that may be non-differentiable. To achieve this, the surrogate is learned via a deep embedding method where the Euclidean distance between the prediction and the ground truth corresponds to the value of the evaluation metric. Additionally, he described his work on proposing a differentiable surrogate loss for the recall metric. To enable training with a very large batch size, which is crucial for metrics computed on the entire retrieval database, the speaker utilized an implementation that sidesteps the hardware constraints of the GPU memory. Furthermore, an efficient mixup approach that operates on pairwise scalar similarities was employed to virtually increase the batch size further.

Building Maximal Vision Systems with Minimal Resources

Dr. Ayush Bansal

Date : 19/12/2022

Abstract:

Current vision and robotic systems are like mainframe machines of the 60s -- they require extensive resources: (1) dense data capture and massive human annotations, (2) large parametric models, and (3) intensive computational infrastructure. I build systems that can learn directly from sparse and unconstrained real-world samples with minimal resources, i.e., limited or no supervision, use simple and efficient models, and operate on every day computational devices. Building systems with minimal resources allows us to democratize them for non-experts. My work has impacted important areas such as virtual reality, content creation and audio-visual editing, and providing a natural voice to speech-impaired individuals.

In my talk, I will present my efforts to build vision systems for novel view synthesis. I will discuss Neural Pixel Composition, a novel approach for continuous 3D-4D view synthesis that reliably operates on sparse and wide-baseline multi-view images/videos and can be trained efficiently within a few minutes for high-resolution (12MP) content using 1 GB GPU memory. I will present my efforts to build vision systems for unsupervised audio-visual synthesis. I will primarily discuss Exemplar Autoencoders that enable zero-shot audio-visual retargeting. Exemplar Autoencoders are built on remarkably simple insights: (1) autoencoders project out-of-sample data onto the distribution of the training set; and (2) exemplar learning enables us to capture the voice, stylistic prosody (emotions and ambiance), and visual appearance of the target. These properties enable an autoencoder trained on an individual's voice to generalize for unknown voices in different languages. Exemplar Autoencoders can synthesize natural voices for speech-impaired individuals and do a zero-shot multilingual translation.

Towards Autonomous Driving in Dense, Heterogeneous, and Unstructured Environments

Dr. Rohan Chandra

Date : 07/11/2022

Abstract:

In this talk, I discuss many key problems in autonomous driving towards handling dense, heterogeneous, and unstructured traffic environments. Autonomous vehicles (AV) at present are restricted to operating on smooth and well-marked roads, in sparse traffic, and among well-behaved drivers. I present new techniques to perceive, predict, and navigate among human drivers in traffic that is significantly denser in terms of a number of traffic-agents, more heterogeneous in terms of size and dynamic constraints of traffic agents, and where many drivers may not follow the traffic rules and have varying behaviors. My talk is structured along three themes—perception, driver behavior modeling, and planning. More specifically, I will talk about Improved tracking and trajectory prediction algorithms for dense and heterogeneous traffic using a combination of computer vision and deep learning techniques. A novel behavior modeling approach using graph theory for characterizing human drivers as aggressive or conservative from their trajectories. Behavior-driven planning and navigation algorithms in mixed and unstructured traffic environments using game theory and risk-aware planning. Finally, I will conclude by discussing the future implications and broader applications of these ideas in the context of social robotics where robots are deployed in warehouses, restaurants, hospitals, and inside homes to assist human beings.