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[Author] Hiroshi SAKO(6hit)

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  • FOREWORD Open Access

    Hiroshi SAKO  

     
    FOREWORD

      Vol:
    E91-D No:7
      Page(s):
    1847-1847
  • Handwritten Numeral String Recognition: Effects of Character Normalization and Feature Extraction

    Cheng-Lin LIU  Hiroshi SAKO  Hiromichi FUJISAWA  

     
    PAPER-String Recognition

      Vol:
    E88-D No:8
      Page(s):
    1791-1798

    The performance of integrated segmentation and recognition of handwritten numeral strings relies on the classification accuracy and the non-character resistance of the underlying character classifier, which is variable depending on the techniques of pattern normalization, feature extraction, and classifier structure. In this paper, we evaluate the effects of 12 normalization functions and four selected feature types on numeral string recognition. Slant correction (deslant) is combined with the normalization functions and features so as to create 96 feature vectors, which are classified using two classifier structures. In experiments on numeral string images of the NIST Special Database 19, the classifiers have yielded very high string recognition accuracies. We show the superiority of moment normalization with adaptive aspect ratio mapping and the gradient direction feature, and observed that slant correction is beneficial to string recognition when combined with good normalization methods.

  • A Neurocomputational Approach to the Correspondence Problem in Computer Vision

    Hiroshi SAKO  Hadar Itzhak AVI-ITZHAK  

     
    PAPER-Image Processing

      Vol:
    E77-D No:4
      Page(s):
    507-515

    A problem which often arises in computer vision is that of matching corresponding points of images. In the case of object recognition, for example, the computer compares new images to templates from a library of known objects. A common way to perform this comparison is to extract feature points from the images and compare these points with the template points. Another common example is the case of motion detection, where feature points of a video image are compared to those of the previous frame. Note that in both of these example, the point correspondence is complicated by the fact that the point sets are not only randomly ordered but have also been distorted by an unknown transformation and having quite different coordinates. In the case of object recognition, there exists a transformation from the object being viewed, to its projection onto the camera's imaging plane, while in the motion detection case, this transformation represents the motion (translation and rotation) of the ofject. If the parameters of the transformation are completely unknow, then all n! permutations must be compared (n : number of feature points). For each permutation, the ensuing transformation is computed using the least-squared projection method. The exponentially large computation required for this is prohibitive. A neural computational method is propopsed to solve these combinatorial problems. This method obtains the best correspondence matching and also finds the associated transform parameters. The method was applied to two dimensional point correspondence and three-to-two dimensional correspondence. Finally, this connectionist approach extends readily to a Boltzmann machine implementation. This implementation is desirable when the transformation is unknown, as it is less sensitive to local minima regardless of initial conditions.

  • Detection of Fundus Lesions Using Classifier Selection

    Hiroto NAGAYOSHI  Yoshitaka HIRAMATSU  Hiroshi SAKO  Mitsutoshi HIMAGA  Satoshi KATO  

     
    PAPER-Biological Engineering

      Vol:
    E92-D No:5
      Page(s):
    1168-1176

    A system for detecting fundus lesions caused by diabetic retinopathy from fundus images is being developed. The system can screen the images in advance in order to reduce the inspection workload on doctors. One of the difficulties that must be addressed in completing this system is how to remove false positives (which tend to arise near blood vessels) without decreasing the detection rate of lesions in other areas. To overcome this difficulty, we developed classifier selection according to the position of a candidate lesion, and we introduced new features that can distinguish true lesions from false positives. A system incorporating classifier selection and these new features was tested in experiments using 55 fundus images with some lesions and 223 images without lesions. The results of the experiments confirm the effectiveness of the proposed system, namely, degrees of sensitivity and specificity of 98% and 81%, respectively.

  • A Hardware Implementation of a Neural Network Using the Parallel Propagated Targets Algorithm

    Anthony V. W. SMITH  Hiroshi SAKO  

     
    PAPER-Hardware

      Vol:
    E77-D No:4
      Page(s):
    516-527

    This document describes a proposal for the implementation of a new VLSI neural network technique called Parallel Propagated Targets (PPT). This technique differs from existing techniques because all layer, within a given network, can learn simultaneously and not sequentially as with the Back Propagation algorithm. the Parallel Propagated Target algorithm uses only information local to each layer and therefore there is no backward flow of information within the network. This allows a simplification in the system design and a reduction in the complexity of implementation, as well as acheiving greater efficiency in terms of computation. Since all synapses can be calculated simultaneously it is possible using the PPT neural algorithm, to parallelly compute all layers of a multi-layered network for the first time.

  • A Hierarchical Classification Method for US Bank-Notes

    Tatsuhiko KAGEHIRO  Hiroto NAGAYOSHI  Hiroshi SAKO  

     
    PAPER-Pattern Discrimination and Classification

      Vol:
    E89-D No:7
      Page(s):
    2061-2067

    This paper describes a method for the classification of bank-notes. The algorithm has three stages, and classifies bank-notes with very low error rates and at high speeds. To achieve the very low error rates, the result of classification is checked in the final stage by using different features to those used in the first two. High-speed processing is mainly achieved by the hierarchical structure, which leads to low computational costs. In evaluation on 32,850 samples of US bank-notes, with the same number used for training, the algorithm classified all samples precisely with no error sample. We estimate that the worst error rate is 3.1E-9 for the classification statistically.

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