44,317 research outputs found
Ensembles of Deep Neural Networks for Action Recognition in Still Images
Despite the fact that notable improvements have been made recently in the
field of feature extraction and classification, human action recognition is
still challenging, especially in images, in which, unlike videos, there is no
motion. Thus, the methods proposed for recognizing human actions in videos
cannot be applied to still images. A big challenge in action recognition in
still images is the lack of large enough datasets, which is problematic for
training deep Convolutional Neural Networks (CNNs) due to the overfitting
issue. In this paper, by taking advantage of pre-trained CNNs, we employ the
transfer learning technique to tackle the lack of massive labeled action
recognition datasets. Furthermore, since the last layer of the CNN has
class-specific information, we apply an attention mechanism on the output
feature maps of the CNN to extract more discriminative and powerful features
for classification of human actions. Moreover, we use eight different
pre-trained CNNs in our framework and investigate their performance on Stanford
40 dataset. Finally, we propose using the Ensemble Learning technique to
enhance the overall accuracy of action classification by combining the
predictions of multiple models. The best setting of our method is able to
achieve 93.17 accuracy on the Stanford 40 dataset.Comment: 5 pages, 2 figures, 3 tables, Accepted by ICCKE 201
Action Recognition in Still Images: Confluence of Multilinear Methods and Deep Learning
Motion is a missing information in an image, however, it is a valuable cue for action recognition. Thus, lack of motion information in a single image makes action recognition for still images inherently a very challenging problem in computer vision. In this dissertation, we show that both spatial and temporal patterns provide crucial information for recognizing human actions. Therefore, action recognition depends not only on the spatially-salient pixels, but also on the temporal patterns of those pixels. To address the challenge caused by the absence of temporal information in a single image, we introduce five effective action classification methodologies along with a new still image action recognition dataset. These include (1) proposing a new Spatial-Temporal Convolutional Neural Network, STCNN, trained by fine-tuning a CNN model, pre-trained on appearance-based classification only, over a novel latent space-time domain, named Ranked Saliency Map and Predicted Optical Flow, or RankSM-POF for short, (2) introducing a novel unsupervised Zero-shot approach based on low-rank Tensor Decomposition, named ZTD, (3) proposing the concept of temporal image, a compact representation of hypothetical sequence of images and then using it to design a new hierarchical deep learning network, TICNN, for still image action recognition, (4) introducing a dataset for STill image Action Recognition (STAR), containing over 1M images across 50 different human body-motion action categories. UCF-STAR is the largest dataset in the literature for action recognition in still images, exposing the intrinsic difficulty of action recognition through its realistic scene and action complexity. Moreover, TSSTN, a two-stream spatiotemporal network, is introduced to model the latent temporal information in a single image, and using it as prior knowledge in a two-stream deep network, (5) proposing a parallel heterogeneous meta- learning method to combine STCNN and ZTD through a stacking approach into an ensemble classifier of the proposed heterogeneous base classifiers. Altogether, this work demonstrates benefits of UCF-STAR as a large-scale still images dataset, and show the role of latent motion information in recognizing human actions in still images by presenting approaches relying on predicting temporal information, yielding higher accuracy on widely-used datasets
Driver Distraction Identification with an Ensemble of Convolutional Neural Networks
The World Health Organization (WHO) reported 1.25 million deaths yearly due
to road traffic accidents worldwide and the number has been continuously
increasing over the last few years. Nearly fifth of these accidents are caused
by distracted drivers. Existing work of distracted driver detection is
concerned with a small set of distractions (mostly, cell phone usage).
Unreliable ad-hoc methods are often used.In this paper, we present the first
publicly available dataset for driver distraction identification with more
distraction postures than existing alternatives. In addition, we propose a
reliable deep learning-based solution that achieves a 90% accuracy. The system
consists of a genetically-weighted ensemble of convolutional neural networks,
we show that a weighted ensemble of classifiers using a genetic algorithm
yields in a better classification confidence. We also study the effect of
different visual elements in distraction detection by means of face and hand
localizations, and skin segmentation. Finally, we present a thinned version of
our ensemble that could achieve 84.64% classification accuracy and operate in a
real-time environment.Comment: arXiv admin note: substantial text overlap with arXiv:1706.0949
Baseline CNN structure analysis for facial expression recognition
We present a baseline convolutional neural network (CNN) structure and image
preprocessing methodology to improve facial expression recognition algorithm
using CNN. To analyze the most efficient network structure, we investigated
four network structures that are known to show good performance in facial
expression recognition. Moreover, we also investigated the effect of input
image preprocessing methods. Five types of data input (raw, histogram
equalization, isotropic smoothing, diffusion-based normalization, difference of
Gaussian) were tested, and the accuracy was compared. We trained 20 different
CNN models (4 networks x 5 data input types) and verified the performance of
each network with test images from five different databases. The experiment
result showed that a three-layer structure consisting of a simple convolutional
and a max pooling layer with histogram equalization image input was the most
efficient. We describe the detailed training procedure and analyze the result
of the test accuracy based on considerable observation.Comment: 6 pages, RO-MAN2016 Conferenc
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