744 research outputs found
Cutting the Error by Half: Investigation of Very Deep CNN and Advanced Training Strategies for Document Image Classification
We present an exhaustive investigation of recent Deep Learning architectures,
algorithms, and strategies for the task of document image classification to
finally reduce the error by more than half. Existing approaches, such as the
DeepDocClassifier, apply standard Convolutional Network architectures with
transfer learning from the object recognition domain. The contribution of the
paper is threefold: First, it investigates recently introduced very deep neural
network architectures (GoogLeNet, VGG, ResNet) using transfer learning (from
real images). Second, it proposes transfer learning from a huge set of document
images, i.e. 400,000 documents. Third, it analyzes the impact of the amount of
training data (document images) and other parameters to the classification
abilities. We use two datasets, the Tobacco-3482 and the large-scale RVL-CDIP
dataset. We achieve an accuracy of 91.13% for the Tobacco-3482 dataset while
earlier approaches reach only 77.6%. Thus, a relative error reduction of more
than 60% is achieved. For the large dataset RVL-CDIP, an accuracy of 90.97% is
achieved, corresponding to a relative error reduction of 11.5%
Knowledge-based best of breed approach for automated detection of clinical events based on German free text digital hospital discharge letters
OBJECTIVES:
The secondary use of medical data contained in electronic medical records, such as hospital discharge letters, is a valuable resource for the improvement of clinical care (e.g. in terms of medication safety) or for research purposes. However, the automated processing and analysis of medical free text still poses a huge challenge to available natural language processing (NLP) systems. The aim of this study was to implement a knowledge-based best of breed approach, combining a terminology server with integrated ontology, a NLP pipeline and a rules engine.
METHODS:
We tested the performance of this approach in a use case. The clinical event of interest was the particular drug-disease interaction "proton-pump inhibitor [PPI] use and osteoporosis". Cases were to be identified based on free text digital discharge letters as source of information. Automated detection was validated against a gold standard.
RESULTS:
Precision of recognition of osteoporosis was 94.19%, and recall was 97.45%. PPIs were detected with 100% precision and 97.97% recall. The F-score for the detection of the given drug-disease-interaction was 96,13%.
CONCLUSION:
We could show that our approach of combining a NLP pipeline, a terminology server, and a rules engine for the purpose of automated detection of clinical events such as drug-disease interactions from free text digital hospital discharge letters was effective. There is huge potential for the implementation in clinical and research contexts, as this approach enables analyses of very high numbers of medical free text documents within a short time period
Parametric classification in domains of characters, numerals, punctuation, typefaces and image qualities
This thesis contributes to the Optical Font Recognition problem (OFR), by developing a classifier system to differentiate ten typefaces using a single English character ‘e’. First, features which need to be used in the classifier system are carefully selected after a thorough typographical study of global font features and previous related experiments. These features have been modeled by multivariate normal laws in order to use parameter estimation in learning. Then, the classifier system is built up on six independent schemes, each performing typeface classification using a different method. The results have shown a remarkable performance in the field of font recognition. Finally, the classifiers have been implemented on Lowercase characters, Uppercase characters, Digits, Punctuation and also on Degraded Images
2D Grammar Extension of the CMP Mathematical Formulae On-line Recognition System
Projecte realitzat en col.laboració amb Czech Technical University in PragueIn the last years, the recognition of handwritten mathematical formulae has recieved an increasing amount of attention in pattern recognition research. However,
the diversity of approaches to the problem and the lack of a commercially
viable system indicate that there is still much research to be done in this area.
In this thesis, I will describe the previous work on a system for on-line handwritten
mathematical formulae recognition based on the structural construction
paradigm and two-dimensional grammars. In general, this approach can be successfully
used in the anaylysis of inputs composed of objects that exhibit rich structural relations. An important benefit of the structural construction is in not
treating symbols segmentation and structural anaylsis as two separate processes
which allows the system to perform segmentation in the context of the whole formula structure, helping to solve arising ambiguities more reliably. We explore the
opening provided by the polynomial complexity parsing algorithm and extend the
grammar by many new grammar production rules which made the system useful
for formulae met in the real world. We propose several grammar extensions
to support a wide range of real mathematical formulae, as well as new features
implemented in the application. Our current approach can recognize functions,
limits, derivatives, binomial coefficients, complex numbers and more
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