See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/339662419 A Review of Image Classification Approaches and Techniques Article · March 2020 DOI: 10.23883/IJRTER.2017.3033.XTS7Z CITATIONS READS 4 307 3 authors, including: Ponnusamy .R Manikandan Kaliyamoorthi Annamalai University SRM Institute of Science and Technology 15 PUBLICATIONS 19 CITATIONS 6 PUBLICATIONS 8 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: A DISTRIBUTIONAL APPROACH FOR IMAGE RETRIEVAL USING HOTELLING'S T-SQUARE STATISTIC View project ANAGLYPH 3D IMAGE ENCRYPTION USING MULTIPLE MEANINGFUL SECRET HIDING SCHEME AND MODIFIED ERROR DIFFUSION View project All content following this page was uploaded by Ponnusamy .R on 16 May 2020. The user has requested enhancement of the downloaded file. A Review of Image Classification Approaches and Techniques R. Ponnusamy1, S. Sathyamoorthy2, K. Manikandan3 1 Department of Technology, Annamalai University, povi2006@yahoo.co.in 2Department of CSE, Annamalai University 3Department of IT, SRM University Abstract—In this paper, a literature survey on the various approaches used for classifying an image which is based on the object. Classification is the vital and challenging task within the field of in computer vision. Classification is based on the description, texture or similarity of items or things. Image classification refers to the labeling of images into one of a number of predefined categories. Pixels are the unit represented in an image. Image classification groups the pixels in different classes. The image classification includes-image acquisition, image pre-processing, image segmentation. Many classification techniques have been developed for image classification. This paper study about different classification techniques such as Artificial Neural Networks (ANN), Naive Bayes (NB), KNearest Neighbor (KNN), Multi- Layered Perceptron (MLP), Kernel Support Vector Machines, Decision Tree (DT), Fuzzy Measure, Radial Basis Function (RBF). Keywords—Image Classification; Artificial Neural Network; Naive Bayes; K-Nearest Neighbour,; Decision Tree; I. INTRODUCTION Classification of the objects is an easy task, but it's challenging to the machine. The image classification includes image pre-processing, image sensors, object detection, object segmentation, feature extraction and object classification. The Image Classification system consists of a database that contains predefined patterns that compare with an object to classify to appropriate category. image classification is a crucial and challenging task in various application domains, including remote sensing, vehicle navigation, biomedical imaging, video-surveillance, biometry, industrial visual inspection, robot navigation, and vehicle navigation [2]. Fig.1 Shows the steps involved in the Classification techniques are[1]: Pre-processing Detection and Extraction Training Classification Figure. 1 Steps for image classification DOI : 10.23883/IJRTER.2017.3033.XTS7Z 1 International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 03; March - 2017 [ISSN: 2455-1457] II. IMAGE CLASSIFICATION METHODS Image classification is one of the important and complex processes in image processing. There are several image classification methods. The two main image classification methods are supervised classification and unsupervised classification. 2.1 Supervised classification In supervised classification some pixels are known grouped and gives the label to classes. This process is known as training. After that classifier uses trained pixels for classify other images. It requires prior information before testing process and it must collected by analyst. In this analyst identifies representative training sites for each informational class and also here algorithm generates decision boundaries. Commonly used supervised classification approaches are parallelepiped, minimum distance to mean and maximum likelihood. The steps in supervised classification approach are: Training areas for each informational class are identified by analyst Signatures identifies(mean, variance, covariance, etc) All pixels are classified Map Informational Class 2.2 Unsupervised classification In unsupervised classification, pixels are grouped with the help of their properties. This process known as clustering and groups are known a cluster. In this user decide how many clusters he wants. The unsupervised classification used when no trained pixels are available. In unsupervised classification, prior information is not needed. It does not require human annotation, it is fully automated. This algorithm identifies clusters in data and also analyst labels clusters. The steps in unsupervised classification are Clustering data All pixels are classified based on clusters Spectral class map Clusters are labeled by analyst Map informational class III. IMAGE CLASSIFICATION TECHNIQUES Image Classification includes following steps: a. Image Acquisition: acquire the images from for image processing. b. Image Pre-Processing: In preprocessing image transformation, noise removal, atmospherically correction techniques are used. c. Feature Extraction: Extracting the important characteristics of the image. d. Classification: The images are classified based on the extracted features into predefined categories by using suitable methods that compare the image pattern with images which inside the database 3.1 Artificial Neural Networks Artificial Neural Network (ANN) is a type of artificial intelligence that limits some functions of the person mind. ANN has a normal tendency for storing experiential knowledge. An ANN consists of a sequence of layer; each layer consists of a set of neurons. All neurons of every layer are linked by weighted connections to all neurons on the preceding and succeeding layers [3]. ANN is a computational model inspired by the biological neural network. It could be considered as a weighted @IJRTER-2017, All Rights Reserved 2 International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 03; March - 2017 [ISSN: 2455-1457] directed graph in which nodes are neurons and edges with weights are connection among the neurons. Each artificial neuron computes a weighted sum of its input signals and generates an output, based on certain activation functions, such as piecewise linear, sigmoid, Gaussian, etc. It consists of one input layer, one output layer, and depending on the application it may or may not have hidden layers. The number of nodes at the output layer is equal to the number of information classes, whereas the number of nodes at the input is equal to the dimensionality of each pixel. Feed-forward ANN with the back propagation learning algorithm is most commonly used in ANN literature. In the learning phase, the network must learn the connection weights iteratively from a set of training samples. The network gives an output, corresponding to each input. The generated output is compared to the desired output. The error between these two is used to modify the weights of the ANN. The training procedure ends when the error becomes less than a predefined threshold. Then, all the testing data are fed into the classifier to perform the classification. [4] 3.2 Naive Bayes classifier The Naive Bayes classifier is based on a probability representation and assigns the class, which has the greatest estimated subsequent probability, to the feature vector extracted from the ROI. This process is optimal when the attributes are orthogonal. However it performs well without this statement. The effortlessness of the method allows good performance with small training sets. Certainly, by building probabilistic models, it is robust to outliers. In addition , it creates soft decision boundaries, which has the outcome of avoiding overtraining. However, the arbitrary option of the distribution model for estimating the probabilities P(x) along with the lack of flexibility of the decision boundaries fallout in limited performance for complex multiclass configurations [5]. 3.3 K-Nearest Neighbor The k-Nearest Neighbor (KNN) classifier cuts out hyper spheres in the space of instances by conveying the majority class of the k-nearest instances according to a defined metric .It is asymptotically optimal and also its implementation allows speedy tests [6]. However, quite a lot of shortcomings are inherent to this method. It is very sensitive to the irritation of the dimensionality [7] Certainly, increasing the dimensionality has the effect to sparse the feature space, and local homogeneous regions that signify the prototypes of the diverse classes are spread out. The classification performance robustly depends upon the used metric. Moreover, a small value of k results in chaotic boundaries and makes the process very aware to outliers. 3.4 Multi- Layered Perceptron Multi-Layered Perceptrons (MLP) are inspired by the human nervous system where in sequence is processed during unified neurons.MLP is a feed-forward neural network, which defines that the information propagates as of input to output. The inputs are fed with principles of each feature and the outputs give the class value. Through one layer of neurons, the output is a weighted linear blend of the inputs. This network is branded as linear perceptron. By totaling an extra layer of neurons with nonlinear foundation functions (the hidden layer), a nonlinear mapping among the input and output is prospective. The teaching phase consists of iterative optimization of the weights concerning the neurons by minimizing the mean squared error rate of organization. The learning rate, which controls the adjustments of the weights throughout the teaching phase, must be elected as a trade-off among mistake on the training set and overtraining. An additional critical constraint is the number of units, of the hidden layer. Definitely, the MLP is subject to over fitting and requires an optimal choice of the parameters for regularization. The MLP can generate models with arbitrary difficulty by drawing infinite decision boundaries. It is also strong to noisy features, as these will find a low weight after teaching. @IJRTER-2017, All Rights Reserved 3 International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 03; March - 2017 [ISSN: 2455-1457] 3.5 Kernel Support Vector Machines Kernel SVMs implicitly map input feature vectors to a higher dimensional space by using the kernel function with the width of the Gaussian. In the transformed space, a maximal extrication hyper plane is built considering a two -class problem. Two parallel hyper planes are constructed symmetrically on both side of the hyper plane that separates the data. The aim is to exploit the distance between the two external hyper planes, called the margin. An declaration is made that the enhanced the margin is, the improved the simplification error of the classifier will exist. Indeed, SVMs were residential according to the structural risk minimization attitude which seeks to minimize an upper clear of the generalization error, while most of the classifiers aim at minimizing the empirical risk, the error on the training set. The SVM algorithm aims at finding a decision function, which minimizes the functional. The SVMs permit training, nonlinear classifiers in high - dimensional spaces using a minute training set. This is enabled during the selection of a division of vectors (called the support vectors) which characterizes the right boundaries between the classes fit [8]. 3.6 Decision Tree Decision Tree (DT) are based on hierarchical rule based method and use Non-parametric approach. Decision Tree calculates class membership by repeatedly partitioning a dataset into uniform subsets Hierarchical classifier permits the acceptations and rejection of class labels at each intermediary stage. This method consists of 3 arts: partitioning the nodes, find the terminal nodes and allocation of class label to terminal nodes. DT are based on hierarchical rule based method and use Nonparametric approach [10]. 3.7 Fuzzy Measure In Fuzzy classification, various stochastic associations are determined to describe characteristics of an image. The various types of stochastic are combined (set of properties) in which the members of this set of properties are fuzzy in nature. It provides the opportunity to describe different categories of stochastic characteristics in the similar form. Performance and accuracy depends upon the threshold selection and fuzzy integral [9]. 3.8 Radial basis function Radial basis functions have received significant attention, most commonly with a Gaussian of the form, || x m || 2 j i g (x ) exp i j 2 2σ i where m i - mean vector(centers), x j input vector Classical techniques utilizing radial basis functions employ some method of determining a subset of centres'. Typically a method of clustering is first employed to select a subset of centres. An attractive feature of the SVM is that this selection is implicit, with each support vectors contributing one local Gaussian function, centred at that data point. By further considerations it is possible to select the global basis function width, s, using the SRM principle [11]. IV. CONCLUSION In this paper we discussed different Image Classification Techniques. Most common approaches for image classification can be categories as supervised and unsupervised, or parametric and nonparametric or object-oriented, sub-pixel, per-pixel and per field or spectral classifiers, contextual classifiers and spectral-contextual classifiers or hard and soft classification. Some of the most commonly used techniques are discussed here. This survey gives theoretical knowledge about classification methods and also for selecting appropriate different classification methods. @IJRTER-2017, All Rights Reserved 4 International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 03; March - 2017 [ISSN: 2455-1457] [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] REFERENCES Jianxin Wu, ”Efficient Hik Svm Learning For Image Classification”, IEEE Transactions On Image Processing, Vol. 21, No. 10, October 2012 Bohyung Han and Larry S. 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