9,341 research outputs found
A Comprehensive Study of ImageNet Pre-Training for Historical Document Image Analysis
Automatic analysis of scanned historical documents comprises a wide range of
image analysis tasks, which are often challenging for machine learning due to a
lack of human-annotated learning samples. With the advent of deep neural
networks, a promising way to cope with the lack of training data is to
pre-train models on images from a different domain and then fine-tune them on
historical documents. In the current research, a typical example of such
cross-domain transfer learning is the use of neural networks that have been
pre-trained on the ImageNet database for object recognition. It remains a
mostly open question whether or not this pre-training helps to analyse
historical documents, which have fundamentally different image properties when
compared with ImageNet. In this paper, we present a comprehensive empirical
survey on the effect of ImageNet pre-training for diverse historical document
analysis tasks, including character recognition, style classification,
manuscript dating, semantic segmentation, and content-based retrieval. While we
obtain mixed results for semantic segmentation at pixel-level, we observe a
clear trend across different network architectures that ImageNet pre-training
has a positive effect on classification as well as content-based retrieval
Rethinking Spatiotemporal Feature Learning: Speed-Accuracy Trade-offs in Video Classification
Despite the steady progress in video analysis led by the adoption of
convolutional neural networks (CNNs), the relative improvement has been less
drastic as that in 2D static image classification. Three main challenges exist
including spatial (image) feature representation, temporal information
representation, and model/computation complexity. It was recently shown by
Carreira and Zisserman that 3D CNNs, inflated from 2D networks and pretrained
on ImageNet, could be a promising way for spatial and temporal representation
learning. However, as for model/computation complexity, 3D CNNs are much more
expensive than 2D CNNs and prone to overfit. We seek a balance between speed
and accuracy by building an effective and efficient video classification system
through systematic exploration of critical network design choices. In
particular, we show that it is possible to replace many of the 3D convolutions
by low-cost 2D convolutions. Rather surprisingly, best result (in both speed
and accuracy) is achieved when replacing the 3D convolutions at the bottom of
the network, suggesting that temporal representation learning on high-level
semantic features is more useful. Our conclusion generalizes to datasets with
very different properties. When combined with several other cost-effective
designs including separable spatial/temporal convolution and feature gating,
our system results in an effective video classification system that that
produces very competitive results on several action classification benchmarks
(Kinetics, Something-something, UCF101 and HMDB), as well as two action
detection (localization) benchmarks (JHMDB and UCF101-24).Comment: ECCV 2018 camera read
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