Abstract
To recognize different patterns, identification of local regions where the pattern classes differ significantly is an inherent ability of the human cognitive system. This inherent ability of human beings may be imitated in any pattern recognition system by incorporating the ability of locating the regions that contain the maximum discriminating information among the pattern classes. In this chapter, the concept of Genetic Algorithm (GA) and Bacterial Foraging Optimization (BFO) are discussed to identify those regions having maximum discriminating information. The discussion includes the evaluation of the methods on the sample images of handwritten Bangla digit and Basic character, which is a subset of Bangla character set. Different methods of sub-image or local region creation such as random creation or based on the Center of Gravity (CG) of the foreground pixels are also discussed here. Longest run features, extracted from the generated local regions, are used as local feature in the present chapter. Based on these extracted local features, together with global features, the algorithms are applied to search for the optimal set of local regions. The obtained results are higher than that results obtained without optimization on the same data set.
TopIntroduction
For recognizing different patterns identification of local regions where the pattern classes differ significantly is an inherent ability of human cognitive system. This inherent ability of human being may be imitated in any pattern recognition system by incorporating the ability of locating the regions which contain the maximum discriminating information among the pattern classes. The simplest way to do this is to divide the pattern image into a fixed number of equal sized regions. These regions may have some overlap with each other. For each such region, features (often called local features) are extracted. These local regions are then sampled randomly to produce various subsets of them. The recognition performance is evaluated with feature set formed with the local features (for some cases along with some global features)of each of those subsets. The subset, which produces best result, may be considered as an optimal set of local regions where the pattern classes differ significantly. Handwritten character recognition is a typical example of a real world pattern recognition problem which requires huge computation and modelling of perceptual power or cognitive capabilities of human beings, at least to some extent. (Cheriet, El Yacoubi, Fujisawa, Lopresti, & Lorette, 2009). To recognize the handwritten characters, both global and local features jointly or individually are used with a standard classifier. Global features are those features which are extracted from the overall character images. On the other hand, local features are extracted from the sub images of the same.
Key Terms in this Chapter
Bacteria Foraging Optimization Algorithm: Bacterial Foraging Optimization Algorithm (BFOA), a swarm intelligence algorithm is based on social and cooperative foraging behaviors of E.coli bacteria found in nature. The process of looking to the regions of high levels of nutrients by a bacteria can be treated as an optimization process. Bacterial Foraging Optimization Algorithm mimic the process to solve a problem. This idea was explored by Bremermann ( Bremermann, 1974 ) and extended later by Passino ( Passino, 2002 ).
Handwritten Character Recognition: The Handwritten character recognition denotes the procedure of recognition of character images in machine editable format such as Unicode or ASCII from the scanned images of handwritten text.
Genetic Algorithm: Genetic algorithm (GA), one of the most popularly used evolutionary tools among soft computing paradigm, is mainly devised to solve real world ill-defined, and imprecisely formulated problems requiring huge computation. It is the power of GA to introduce some heuristic methodologies to minimize the search space for optimal solution(s) without sticking at local optima. Due to the inherent power, GA becomes one of the most successful heuristic optimization algorithms. It is widely used to solve problems of diversified fields ranging from engineering to art.
Local Region Selection: The inherent ability of human is to recognize different patterns by focusing on sub-regions or local regions containing maximum discriminatory information. Local region selection procedure denotes identification of those local regions having maximum discriminating properties among inter class patterns and minimum discriminating properties among intra class patterns.
Handwritten Bangla Basic Character or Numeral Recognition: The Handwritten Bangla Basic character or Numeral recognition is the system by which handwritten Bangla Basic characters or Numerals are scanned into image format and recognize them into machine identifiable format. The process generally includes extraction of features from scanned images, classification of the images by a classifier based on the extracted images. It is worthy to mention here Bangla Basic character consists of 11 vowels and 39 consonants.
Global and Local Features: Global features are those features which are extracted from the overall character images. On the other hand, local features are extracted from the sub images of the same.
Evolutionary Algorithms: Evolutionary algorithm is used to describe the computational models of evolutionary processes which consists of rules of selection and other operators, such as recombination and mutation as key elements in their design and implementation. After initializing the first population structures, EA evaluates the population and used different selection, recombination, and mutation to generate new population. In this way it reaches towards the goal.