1,051 research outputs found
Human Attention in Image Captioning: Dataset and Analysis
In this work, we present a novel dataset consisting of eye movements and
verbal descriptions recorded synchronously over images. Using this data, we
study the differences in human attention during free-viewing and image
captioning tasks. We look into the relationship between human attention and
language constructs during perception and sentence articulation. We also
analyse attention deployment mechanisms in the top-down soft attention approach
that is argued to mimic human attention in captioning tasks, and investigate
whether visual saliency can help image captioning. Our study reveals that (1)
human attention behaviour differs in free-viewing and image description tasks.
Humans tend to fixate on a greater variety of regions under the latter task,
(2) there is a strong relationship between described objects and attended
objects ( of the described objects are being attended), (3) a
convolutional neural network as feature encoder accounts for human-attended
regions during image captioning to a great extent (around ), (4)
soft-attention mechanism differs from human attention, both spatially and
temporally, and there is low correlation between caption scores and attention
consistency scores. These indicate a large gap between humans and machines in
regards to top-down attention, and (5) by integrating the soft attention model
with image saliency, we can significantly improve the model's performance on
Flickr30k and MSCOCO benchmarks. The dataset can be found at:
https://github.com/SenHe/Human-Attention-in-Image-Captioning.Comment: To appear at ICCV 201
Grad-CAM++: Improved Visual Explanations for Deep Convolutional Networks
Over the last decade, Convolutional Neural Network (CNN) models have been
highly successful in solving complex vision problems. However, these deep
models are perceived as "black box" methods considering the lack of
understanding of their internal functioning. There has been a significant
recent interest in developing explainable deep learning models, and this paper
is an effort in this direction. Building on a recently proposed method called
Grad-CAM, we propose a generalized method called Grad-CAM++ that can provide
better visual explanations of CNN model predictions, in terms of better object
localization as well as explaining occurrences of multiple object instances in
a single image, when compared to state-of-the-art. We provide a mathematical
derivation for the proposed method, which uses a weighted combination of the
positive partial derivatives of the last convolutional layer feature maps with
respect to a specific class score as weights to generate a visual explanation
for the corresponding class label. Our extensive experiments and evaluations,
both subjective and objective, on standard datasets showed that Grad-CAM++
provides promising human-interpretable visual explanations for a given CNN
architecture across multiple tasks including classification, image caption
generation and 3D action recognition; as well as in new settings such as
knowledge distillation.Comment: 17 Pages, 15 Figures, 11 Tables. Accepted in the proceedings of IEEE
Winter Conf. on Applications of Computer Vision (WACV2018). Extended version
is under review at IEEE Transactions on Pattern Analysis and Machine
Intelligenc
Visual Entailment: A Novel Task for Fine-Grained Image Understanding
Existing visual reasoning datasets such as Visual Question Answering (VQA),
often suffer from biases conditioned on the question, image or answer
distributions. The recently proposed CLEVR dataset addresses these limitations
and requires fine-grained reasoning but the dataset is synthetic and consists
of similar objects and sentence structures across the dataset.
In this paper, we introduce a new inference task, Visual Entailment (VE) -
consisting of image-sentence pairs whereby a premise is defined by an image,
rather than a natural language sentence as in traditional Textual Entailment
tasks. The goal of a trained VE model is to predict whether the image
semantically entails the text. To realize this task, we build a dataset SNLI-VE
based on the Stanford Natural Language Inference corpus and Flickr30k dataset.
We evaluate various existing VQA baselines and build a model called Explainable
Visual Entailment (EVE) system to address the VE task. EVE achieves up to 71%
accuracy and outperforms several other state-of-the-art VQA based models.
Finally, we demonstrate the explainability of EVE through cross-modal attention
visualizations. The SNLI-VE dataset is publicly available at
https://github.com/ necla-ml/SNLI-VE
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