We develop a representation suitable for the unconstrained recognition of
words in natural images: the general case of no fixed lexicon and unknown
length.
To this end we propose a convolutional neural network (CNN) based
architecture which incorporates a Conditional Random Field (CRF) graphical
model, taking the whole word image as a single input. The unaries of the CRF
are provided by a CNN that predicts characters at each position of the output,
while higher order terms are provided by another CNN that detects the presence
of N-grams. We show that this entire model (CRF, character predictor, N-gram
predictor) can be jointly optimised by back-propagating the structured output
loss, essentially requiring the system to perform multi-task learning, and
training uses purely synthetically generated data. The resulting model is a
more accurate system on standard real-world text recognition benchmarks than
character prediction alone, setting a benchmark for systems that have not been
trained on a particular lexicon. In addition, our model achieves
state-of-the-art accuracy in lexicon-constrained scenarios, without being
specifically modelled for constrained recognition. To test the generalisation
of our model, we also perform experiments with random alpha-numeric strings to
evaluate the method when no visual language model is applicable.

本研究提出一种基于卷积神经网络和条件随机场的模型，通过预测字符和 N-grams 以识别自然图像中词语，同时实现多任务学习，无需有固定的单词列表，实验证明其在标准实际文本识别基准中的准确性优于仅预测字符，也达到了有限词汇识别的最高精度。

无约束文本识别的深度结构化输出学习

Deep Structured Output Learning for Unconstrained Text Recognition

We consider the problem of depth estimation from a single monocular image in
this work. It is a challenging task as no reliable depth cues are available,
e.g., stereo correspondences, motions, etc. Previous efforts have been focusing
on exploiting geometric priors or additional sources of information, with all
using hand-crafted features. Recently, there is mounting evidence that features
from deep convolutional neural networks (CNN) are setting new records for
various vision applications. On the other hand, considering the continuous
characteristic of the depth values, depth estimations can be naturally
formulated into a continuous conditional random field (CRF) learning problem.
Therefore, we in this paper present a deep convolutional neural field model for
estimating depths from a single image, aiming to jointly explore the capacity
of deep CNN and continuous CRF. Specifically, we propose a deep structured
learning scheme which learns the unary and pairwise potentials of continuous
CRF in a unified deep CNN framework.
The proposed method can be used for depth estimations of general scenes with
no geometric priors nor any extra information injected. In our case, the
integral of the partition function can be analytically calculated, thus we can
exactly solve the log-likelihood optimization. Moreover, solving the MAP
problem for predicting depths of a new image is highly efficient as closed-form
solutions exist. We experimentally demonstrate that the proposed method
outperforms state-of-the-art depth estimation methods on both indoor and
outdoor scene datasets.

本文提出了一种在单个图像中利用深度卷积神经网络和连续条件随机场进行深度估计的方法，通过结构化学习方案统一学习了连续 CRF 的一元和二元潜力，并通过实验证明了其在室内和户外场景数据集上优于现有深度估计方法。

基于深度卷积神经场的单张图像深度估计

Deep Convolutional Neural Fields for Depth Estimation from a Single  Image

We introduce a framework for unsupervised learning of structured predictors
with overlapping, global features. Each input's latent representation is
predicted conditional on the observable data using a feature-rich conditional
random field. Then a reconstruction of the input is (re)generated, conditional
on the latent structure, using models for which maximum likelihood estimation
has a closed-form. Our autoencoder formulation enables efficient learning
without making unrealistic independence assumptions or restricting the kinds of
features that can be used. We illustrate insightful connections to traditional
autoencoders, posterior regularization and multi-view learning. We show
competitive results with instantiations of the model for two canonical NLP
tasks: part-of-speech induction and bitext word alignment, and show that
training our model can be substantially more efficient than comparable
feature-rich baselines.

本文介绍了一个用于重叠的全局特征的无监督学习结构化预测的框架，提出了一个基于特征丰富的条件随机场对可观察数据进行条件预测的潜在表示方法，并使用具有封闭形式的最大似然估计的模型来（重新）生成输入的重建，使得无需进行不切实际的独立性假设或限制可用特征类型的情况下能够有效地进行学习，并示范了与传统自动编码器、后验正则化和多视图学习方面的有见地的联系。接着将模型实例化应用于两个经典的自然语言处理任务：词性归纳和比对文本词汇对应，并证明训练我们的模型可以比可比的特征丰富基线方法更加高效。