Abstract

Many image filtering operations provide ample par-allelism, but progressive non-linear processing of im-ages is among the hardest to parallelize due to long,sequential, and non-linear data dependency. A typicalexample of such an operation is error diffusion dither-ing, exemplified by the Floyd-Steinberg algorithm. Inthis paper, we present its parallelization on multicoreCPUs using a block-based approach and on the GPUusing a pixel based approach. We also present a hybridapproach in which the CPU and the GPU operatein parallel during the computation. High PerformanceComputing has traditionally been associated with highend CPUs and GPUs. Our focus is on everyday com-puters such as laptops and desktops, where significantcompute power is available on the GPU as on theCPU. Our implementation can dither an8K8Kimage on an off-the-shelf laptop with an Nvidia 8600MGPU in about 400 milliseconds when the sequentialimplementation on its CPU took about 4 seconds.

Abstract

K-Means is a popular clustering algorithm with wideapplications in Computer Vision, Data mining, Data Visu-alization, etc. Clustering is an important step for indexingand searching of documents, images, video, etc. Clusteringlarge numbers of high-dimensional vectors is very compu-tation intensive. In this paper, we present the design andimplementation of theK-Means clustering algorithm on themodern GPU. All steps are performed entirely on the GPUefficiently in our approach. We also present a load balancedmulti-node, multi-GPU implementation which can handleup to 6 million, 128-dimensional vectors. We use efficientmemory layout for all steps to get high performance. TheGPU accelerators are now present on high-end workstationsand low-end laptops. Scalability in the number and dimen-sionality of the vectors, the number of clusters, as well as inthe number of cores available for processing are importantfor usability to different users. Our implementation scaleslinearly or near-linearly with different problem parameters.We achieve up to 2 times increase in speed compared to thebest GPU implementation forK-Means on a single GPU.We obtain a speed up of over 170 on a single Nvidia FermiGPU compared to a standard sequential implementation.We are able to execute one iteration ofK-Means in 136seconds on off-the-shelf GPUs to cluster 6 million vectorsof 128 dimensions into 4K clusters and in 2.5 seconds tocluster 125K vectors of 128 dimensions into 2K clusters.

Abstract

Interaction of proline with gold cluster was studied using density functional theory (DFT). Two types of mixed basis sets UB3LYP/6-311++G LANL2MB and UB3LYP/6-311++G LANL2DZ were used for optimization of complex structures. Proline interacts with gold cluster either through one anchor bond, N-Au or an anchor bond O-Au associated with a non-conventional O-H…Au hydrogen bond. Among these interactions, higher tendency for interaction is seen with Au cluster through amide terminal. Natural bond orbital analysis (NBO) is used to substantiate the results.

Abstract

We have applied genetic algorithm optimization for the design of laser pulses to control dissociation process in the ground electronic state of HF molecule, within the mathematical framework of optimal control theory. In order to design the experimentally feasible laser fields, we coded the small set of selected field parameters in the GA parameter space. Two types of pulses, one with fixed frequency components and the other having non-deterministic components have been designed. Optimized laser field obtained using this approach, possesses simple time and frequency structures. We show that the fields having non-deterministic frequency components lead to greater dissociation probability compared to the ones having deterministic frequency components.

Abstract

Video Scene Segmentation is an important problem in computer vision as it helps in efficient storage, indexing and retrieval of videos. Significant amount of work has been done in this area in the form of shot segmentation techniques and they often give reasonably good results. However, shots are not of much importance for the semantic analysis of the videos. For semantic and meaningful analysis of the videos (e.g. movies), scene is more important since it captures one complete unit of action. People have tried different approaches in scene segmentation but almost all of them use color, texture etc. to compute scene boundaries. In this paper, we propose a new algorithm based on a Bag of Words(BoW) representation which computes semantic similarity between shots using a Bipartite Graph Model (BGM). Based on semantic similarity, we detect the scene boundaries in the movie. We have tested our algorithm on a multiple Hollywood movies, and the proposed method is found to give good results.

Abstract

A major requirement in the design of robust OCRs is the invariance of feature extraction scheme with the popular fonts used in the print. Many statistical and structural features have been tried for character classification in the past. In this paper, we get motivated by the recent successes in object category recognition literature and use a spatial extension of the histogram of oriented gradients (HOG) for character classification. Our experiments are conducted on 1453950 Telugu character samples in 359 classes and 15 fonts. On this data set, we obtain an accuracy of 96-98% with an SVM classifier.

Abstract

This paper presents integration and testing scheme for managing a large Multilingual OCR Project. The project is an attempt to implement an integrated platform for OCR of different Indian languages. Software engineering, workflow management and testing processes have been discussed in this paper. The OCR has now been experimentally deployed for some specific applications and currently is being enhanced for handling the space and time constraints, achieving higher recognition accuracies and adding new functionalities.

Abstract

Page segmentation is a basic step in any character recognition system. Its failure is one of the major causes for deteriorating overall accuracy of the current Indian language OCR engines. Many segmentation algorithms are proposed in literature. Often these algorithms fail to adapt dynamically to a given page and thus tend to yield poor segmentation for some specific regions or some specific pages. Given the ground truth, locating page segmentation errors is a straight foreword problem and merely useful for comparing segmentation algorithms. In this work, we locate segmentation errors without directly using the ground truth. Such automatic localization of page segmentation errors can be considered a major step towards improving page segmentation errors. In this work, we focus on localizing line level segmentation errors. We perform experiments on more than 18000 scanned pages of 109 books belonging to four prominent south Indian languages.

Abstract

Inspired by the success of MRF models for solving object segmentation problems, we formulate the binarization problem in this framework. We represent the pixels in a document image as random variables in an MRF, and introduce a new energy (or cost) function on these variables. Each variable takes a foreground or background label, and the quality of the binarization (or labelling) is determined by the value of the energy function. We minimize the energy function, i.e. find the optimal binarization, using an iterative graph cut scheme. Our model is robust to variations in foreground and background colours as we use a Gaussian Mixture Model in the energy function. In addition, our algorithm is efficient to compute, and adapts to a variety of document images. We show results on word images from the challenging ICDAR 2003 dataset, and compare our performance with previously reported methods. Our approach shows significant improvement in pixel level accuracy as well as OCR accuracy.

Abstract

In this paper, we present a novel approach to search and retrieve from document image collections, without explicit recognition. Existing recognition-free approaches such as word-spotting cannot scale to arbitrarily large vocabulary and document image collections. In this paper we put forth a framework that overcomes three issues of word-spotting: i) retrieving word images not labeled during indexing, ii) allow for query and retrieval of morphological variations of words and iii) scale the retrieval to large collections. We propose a character n-gram spotting framework, where word-images are considered as a bag of visual n-grams. The character n-grams are represented in a visual-feature space and indexed for quick retrieval. In the retrieval phase, the query word is expanded to its constituent n-grams, which are used to query the previously built index. A ranking mechanism is proposed that combines the retrieval results from the multiple lists corresponding to each n-gram. The approach is demonstrated on a size-able collection of English and Malayalam books. With a mean AP of 0.64, the performance of the retrieval system was found to be very promising.