Computer Science

In this paper we talk about speeding up calculation of graph metrics and layout with NodeXL by exploiting the parallel architecture of modern day Graphics Processing Units (GPU), specifically Compute Unified Device Architecture (CUDA) by Nvidia. Graph centrality metrics like Eigenvector, Betweenness, Page Rank and layout algorithms like Fruchterman-Rheingold are essential components of Social Network Analysis (SNA). With the growth in adoption of SNA in different domains and increasing availability of huge networked datasets for analysis, social network analysts are looking for tools that are faster and more scalable. Our results show up to 802 times speedup for a Fruchterman-Rheingold graph layout and up to 17,972 times speedup for Eigenvector centrality metric calculations

The American Recovery and Reinvestment Act dedicated $787 billion to stimulate the US economy and mandated the release of the data describing the exact distribution of that money. The dataset is a large and complex one; one of its distinguishing features is its bi-hierarchical structure, arising from the distribution of money through agencies to specific projects and the natural aggregation of awards based on location. To offer a comprehensive overview of the data, a visualization must incorporate both these hierarchies. We present TreeCovery, a tool that accomplishes this through the use of two coordinated treemaps. The tool includes a number of innovative features, including coordinated zooming and filtering and a proportional highlighting technique across the two trees. TreeCovery was designed to facilitate data exploration, and initial user studies suggest that it will be helpful in insight generation. RATB(Recovery Accountability and Transparency Board) has tested TreeCovery and considering to include the concept into their visual analytics.

This paper reviews the trajectory of three information visualization innovations: treemaps, conetrees, and hyperbolic trees. These three ideas were first published in the early 1990s, so we are able to track academic publications, patents, trade press articles over almost two decades. We describe the early history of each approach, problems with data collection from differing sources, appropriate metrics, and strategies for visualizing these longitudinal data sets. This paper makes two contributions: (1) it offers the information visualization community a history of how certain ideas evolved, influenced others, and were adopted for widespread use and (2) it provides example of how such trajectories of historical trends can be gathered and visualized. Guidance for innovators and future analysts is offered.

This paper presents a three-part experiment designed to investigate the motivations of users of a community safety and neighborhood watch social networking website. The experiment centers around an intervention into the invitation system that current users employ to invite nonmembers to join the site, and involves several versions of an invitation email which differ by expressing one of four possible motivations for using such a site. The research presented investigates how potential users' choice of whether or not to join the site is affected by the use case presented by the invitation. It also includes an investigation of the motivations of current users of the site, as reported in an online survey. The experiment yielded no significant difference in responses to the emails. Overall, invitations that included a specific motivation slightly outperformed those which did not, but not to a statistically significant degree. We conclude that although users have specific motivations for using the site, as reported in the survey, attempting to increase response rates to invitation emails by suggesting use cases of the site is surprisingly unlikely to be successful.

In document images, we often find printed lines over-lapping with hand written elements especially in case of signatures. Typical examples of such images are bank cheques and payment slips. Although the detection and removal of the horizontal lines has been addressed, the restoration of the handwritten area after removal of lines, persists to be a problem of interest. In this paper, we propose a method for line removal and restoration of the erased areas of the handwritten elements. Subjective evaluation of the results have been conducted to analyze the effectiveness of the proposed method. The results are promising with an accuracy of 86.33%. The entire process takes less than half a second for completion on a 2.4 GHz 512 MB RAM Pentium IV PC for a document image.

In this paper, we present a novel graph-based method for extracting handwritten text lines in monochromatic Arabic document images. Our approach consists of two steps -Coarse text line estimation using primary components which define the line and assignment of diacritic components which are more difficult to associate with a given line. We first estimate local orientation at each primary component to build a sparse similarity graph. We then, use a shortest path algorithm to compute similarities between non-neighboring components. From this graph, we obtain coarse text lines using two estimates obtained from Affinity propagation and Breadth-first search. In the second step, we assign secondary components to each text line. The proposed method is very fast and robust to non-uniform skew and character size variations, normally present in handwritten text lines. We evaluate our method using a pixel-matching criteria, and report 96% accuracy on a dataset of 125 Arabic document images. We also present a proximity analysis on datasets generated by artificially decreasing the spacings between text lines to demonstrate the robustness of our approach.

In this paper we present a novel method for removing page rule lines in monochromatic handwritten Arabic documents using subspace methods with minimal effect on the quality of the foreground text. We use moment and histogram properties to extract features that represent the characteristics of the underlying rule lines. A linear subspace is incrementally built to obtain a line model that can be used to identify rule line pixels. We also introduce a novel scheme for evaluating noise removal algorithms in general and we use it to assess the quality of our rule line removal algorithm. Experimental results presented on a data set of 50 Arabic documents, handwritten by different writers, demonstrate the effectiveness of the proposed method.

In this paper, we present a novel method for extracting handwritten and printed text zones from noisy document images with mixed content. We use Triple-Adjacent-Segment (TAS) based features which encode local shape characteristics of text in a consistent manner. We first construct two codebooks of the shape features extracted from a set of handwritten and printed text documents respectively. We then compute the normalized histogram of codewords for each segmented zone and use it to train a Support Vector Machine (SVM) classifier. The codebook based approach is robust to the background noise present in the image and TAS features are invariant to translation, scale and rotation of text. In experiments, we show that a pixel-weighted zone classification accuracy of 98% can be achieved for noisy Arabic documents. Further, we demonstrate the effectiveness of our method for document page classification and show that a high precision can be achieved for the detection of machine printed documents. The proposed method is robust to the size of zones, which may contain text content at line or paragraph level.

This paper presents an approach to textline extraction in handwritten document images which combines local and global techniques. We propose a graph-based technique to detect touching and proximity errors that are common with handwritten text lines. In a refinement step, we use Expectation-Maximization (EM) to iteratively split the error segments to obtain correct text-lines. We show improvement in accuracies using our correction method on datasets of Arabic document images. Results on a set of artificially generated proximity images show that the method is effective for handling touching errors in handwritten document images.

Images of document pages have different characteristics than images of natural scenes, and so the sharpness measures developed for natural scene images do not necessarily extend to document images primarily composed of text. We present an efficient and simple method for effectively estimating the sharpness/blurriness of document images that also performs well on natural scenes. Our method can be used to predict the sharpness in scenarios where images are blurred due to camera-motion (or hand-shake), defocus, or inherent properties of the imaging system. The proposed method outperforms the perceptually-based, no-reference sharpness work of [1] and , which was shown to perform better than 14 other no-reference sharpness measures on the LIVE dataset.

In this paper, we present a method for the retrieval of document images with chosen layout characteristics. The proposed method is based on statistics of patchcodewords over different regions of image. We begin with a set of wanted and a random set of unwanted images representative of a large heterogeneous collection. We then use raw-image patches extracted from the unlabeled images to learn a codebook. To model the spatial relationships between patches, the image is recursively partitioned horizontally and vertically, and a histogram of patch-codewords is computed in each partition. The resulting set of features give a high precision and recall for the retrieval of hand-drawn and machine-print table-documents, and unconstrained mixed form-type documents, when trained using a random forest classifier. We compare our method to the spatial-pyramid method, and show that the proposed approach for learning layout characteristics is competitive for document images.

In this paper, we present an efficient general-purpose objective no-reference (NR) image quality assessment (IQA) framework based on unsupervised feature learning. The goal is to build a computational model to automatically predict human perceived image quality without a reference image and without knowing the distortion present in the image. Previous approaches for this problem typically rely on hand-crafted features which are carefully designed based on prior knowledge.

In this paper, we present a codebook based method for handwritten text-line segmentation which uses imagepatches in the training data to learn a graph-based similarity for clustering. We first construct a codebook of image-patches using K-medoids, and obtain exemplars which encode local evidence. We then obtain the corresponding codewords for all patches extracted from a given image and construct a similarity graph using the learned evidence and partitioned to obtain textlines. Our learning based approach performs well on a field dataset containing degraded and un-constrained handwritten Arabic document images. Results on ICDAR 2009 segmentation contest dataset show that the method is competitive with previous approaches.

The labeling of large sets of images for training or testing analysis systems can be a very costly and timeconsuming process. Multiple instance learning (MIL) is a generalization of traditional supervised learning which relaxes the need for exact labels on training instances. Instead, the labels are required only for a set of instances known as bags. In this paper, we apply MIL to the retrieval and localization of signatures and the retrieval of images containing machine-printed text, and show that a gain of 15-20% in performance can be achieved over the supervised learning with weak-labeling. We also compare our approach to supervised learning with fully annotated training data and report a competitive accuracy for MIL. Using our experiments on real-world datasets, we show that MIL is a good alternative when the training data has only document-level annotation.

In this paper, we present a fast and effective method for removing pre-printed rule-lines in handwritten document images. We use an integral-image representation which allows fast computation of features and apply techniques for large scale Support Vector learning using a data selection strategy to sample a small subset of training data. Results on both constructed and real-world data sets show that the method is effective for rule-line removal. We compare our method to a subspace-based method and show that better accuracy can be achieved in considerably less time. The integral-image based features proposed in the paper are generic and can be applied to other problems as well.

We propose a novel method for binarization of color documents whereby the foreground text is output as black and the background as white regardless of the polarity of foreground-background shades. The method employs an edge-based connected component approach and automatically determines a threshold for each component. It has several advantages over existing binarization methods. Firstly, it can handle documents with multi-colored texts with different background shades. Secondly, the method is applicable to documents having text of widely varying sizes, usually not handled by local binarization methods. Thirdly, the method automatically computes the threshold for binarization and the logic for inverting the output from the image data and does not require any input parameter. The proposed method has been applied to a broad domain of target document types and environment and is found to have a good adaptability.

In this paper, we present a fast and effective method for removing pre-printed rule-lines in handwritten document images. We use an integral-image representation which allows fast computation of features and apply techniques for large scale Support Vector learning using a data selection strategy to sample a small subset of training data. Results on both constructed and real-world data sets show that the method is effective for rule-line removal. We compare our method to a subspace-based method and show that better accuracy can be achieved in considerably less time. The integral-image based features proposed in the paper are generic and can be applied to other problems as well.

The proposed paper will present details on recent advancements in scientific computing in terms of integrating new hardware and software to greatly enhance the computational efficiency of comprehensive rotorcraft analysis. The focus will be on showing the tremendous computational accelerations that are possible (ie, orders of magnitude speed up) by using software developments in the form of the fast multipole method (FMM) combined with hardware accelerations by using graphics processors (GPUs).