Assessment of OCR Quality and Font Identification in Historical Documents

Mass digitization of historical documents is a challenging problem for optical character recognition (OCR) tools. Issues include noisy backgrounds and faded text due to aging, border/marginal noise, bleed-through, skewing, warping, as well as irregular fonts and page layouts. As a result, OCR tools often produce a large number of spurious bounding boxes (BBs) in addition to those that correspond to words in the document. To improve the OCR output, in this thesis we develop machine-learning methods to assess the quality of historical documents and label/tag documents (with the page problems) in the EEBO/ECCO collections—45 million pages available through the Early Modern OCR Project at Texas A&M University. We present an iterative classification algorithm to automatically label BBs (i.e., as text or noise) based on their spatial distribution and geometry. The approach uses a rule-base classifier to generate initial text/noise labels for each BB, followed by an iterative classifier that refines the initial labels by incorporating local information to each BB, its spatial location, shape and size. When evaluated on a dataset containing over 72,000 manually-labeled BBs from 159 historical documents, the algorithm can classify BBs with 0.95 precision and 0.96 recall. Further evaluation on a collection of 6,775 documents with ground-truth transcriptions shows that the algorithm can also be used to predict document quality (0.7 correlation) and improve OCR transcriptions in 85% of the cases. This thesis also aims at generating font metadata for historical documents. Knowledge of the font can aid OCR system to produce very accurate text transcriptions, but getting font information for 45 million documents is a daunting task. We present an active learning based font identification system that can classify document images into fonts. In active learning, a learner queries the human for labels on examples it finds most informative. We capture the characteristics of the fonts using word image features related to character width, angled strokes, and Zernike moments. To extract page level features, we use bag-of-word feature (BoF) model. A font classification model trained using BoF and active learning requires only 443 labeled instances to achieve 89.3% test accuracy

Toward More Scalable Off-Line Simulations of MPI Applications

International audienceThe off-line (or post-mortem) analysis of execution event traces is a popular approach to understand the performance of HPC applications that use the message passing paradigm. Combining this analysis with simulation makes it possible to " replay " the application execution to explore " what if? " scenarios, e.g., assessing application performance in a range of (hypothetical) execution environments. However, such off-line analysis faces scalability issues for acquiring, storing, or replaying large event traces. We first present two previously proposed and complementary frameworks for off-line replaying of MPI application event traces, each with its own objectives and limitations. We then describe how these frameworks can be combined so as to capitalize on their respective strengths while alleviating several of their limitations. We claim that the combined framework affords levels of scalability that are beyond that achievable by either one of the two individual frameworks. We evaluate this framework to illustrate the benefits of the proposed combination for a more scalable off-line analysis of MPI applications

Head Mounted Eye Tracking Aid for Central Visual Field Loss

University of Minnesota M.S.M.E. thesis. July 2016. Major: Mechanical Engineering. Advisor: Arthur Erdman. 1 computer file (PDF); viii, 137 pages.Age-Related Macular Degeneration results in central visual field loss (CFL) due to formation of central blind-spots or scotomas. Activities like reading are affected. We hypothesize that real-time remapping of lost information due to CFL onto a functional portion of the retina will improve visual performance. We have developed two hardware prototypes using a head-mounted display, integrated eye-tracker, and computer to remap and display images in real-time to the wearer. To test, in three different studies, normally-sighted subjects were asked to wear the head-mounted display with the built-in eye tracker. CFL was simulated by placing artificial circular scotomas ranging from 2° to 16° diameter over the gaze position, and reading speed was measured for the remapped and unremapped condition. We observed a statistically significant increase in mean reading speeds for the larger scotomas. Results indicate that the device shows promise for use with CFL patients