A Survey: Neural Network in the field of Face Recognition System Madhulata Pushpakar Reshamlal Pradhan MCA pursuing MSIT Department Mats University, Raipur MTech madhupushpakar6@gmail.co m ABSTRACT Face recognition has been studied for many years and has practical application in areas such as security systems, detection of criminals and help with speech identification system. The Face Recognition System is an automated system to identify a human face and emotions. There are several methods which are tested in an efficient way for facial expression recognition purpose. The artificial neural network is one of the most optimization techniques used for training the networks for efficient recognition. In this paper an overview of neural network in the field of face recognition system is provided. A discussion outlining the neural network for facial expression detection is provided with articles of various authors. What should be the alternative classification techniques for face recognition is also discussed. Keywords Feature classification, Face recognition, Feature extraction, Neural Network, Feedback Neural Network, Feed forward Neural Network. 1. INTRODUCTION Face Recognition is a term that includes several subproblems. There are different classifications of these problems in the bibliography. Some of them will be explained on this section. Finally, a general or unified classification will be proposed. Face recognition has been studied for many years and has practical application in areas such as security systems, detection of criminals and help with speech identification system. The Face Recognition System is a system that automatically identifies a human face and emotions. The face recognition problem is difficult problem for human because it represents complex, multidimensional, meaningful visual motivation. Face Recognition is important to human because the face plays a major role in social intercourse, conveying emotions and feelings. Biometric is the science and machinery of recording and authenticate individuality using physiological or behavioral characteristics of the subject. It is a computable quality, whether physiological or behavioral, of a living organism that can be used to Mats University, Raipur reshamlalpradhan6602@gm ail.com differentiate that organism as an individual. Biometric data is captured when the user makes an try to be authenticated by the system. This data is used by the biometric system for real-time comparison against biometric samples. Biometrics offers the identity of an individual may be viewed as the information associated with that person in a particular identity management system. 1.1 A generic face recognition system A good face recognition system must be healthy to overcome these difficulties and generalize over many conditions to capture the essential similarities for a given human face. The input of a face recognition system is always an image or video stream. The output is an identification or verification of the subject or subjects that Appear in the image or video. Some approaches define a face recognition system as a three step process – see Figure:1.1. From this point of view, the Face Detection and Feature Extraction phases could run simultaneously. Fig:1.1 Face recognition system 1.2 Face detection Now a days some applications of Face Recognition don’t require face detection. In some cases, face images stored in the data bases are already normalized. There is a standard image input format, so there is no need for a detection step. An example of this could be a criminal data base. There, the law enforcement agency stores faces of people with a criminal report. If there is new subject and the police has his or her passport photograph, face detection is not necessary. However, the conventional input image of computer vision systems are not that suitable. They can contain many items or faces. 1.3 Face tracking Many face recognition systems have a video sequence as the input. Those systems may require to be capable of not only detecting but tracking faces. Face tracking is essentially a motion estimation problem. Face tracking can be performed using many different methods, e.g., head tracking, feature tracking, image-based tracking, model-based tracking. These are different ways to classify these algorithms: Head tracking/Individual feature tracking. The head can be tracked a whole entity, or certain features tracked individually. 2D/3D. Two dimensional systems track a face and output an image space where the face is located. Three dimensional systems, on the other hand, perform a 3D modeling of the face. This approach allows to estimate pose or orientation variations. 1.4 Feature Extraction Humans can recognize faces since we are 5 year old. It seems to be an automated and dedicated process in our brains, though it’s a much debated issue . What it’s clear is that we can recognize people we know, even when they are wearing glasses or hats. We can also recognize men who have grown a beard. It’s not very difficult for us to see our grandma’s wedding photo and recognize her, although she was 23 years old. All these processes seem trivial, but they represent a challenge to the computers. In fact, face recognition’s core problem is to extract information from photographs. This feature extraction process can be defined as the procedure of extracting relevant information from a face image. every possible subset and choose the one that fulfills the criterion function. However, this can become an unaffordable task in terms of computational time. Some effective approaches to this problem are based on algorithms like branch and bound algorithms. 1.6 Face classification Once the features are extracted and selected, the next step is to classify the image. Appearance-based face recognition algorithms use a wide variety of classification methods. Sometimes two or more classifiers are combined to achieve better results. On the other hand, most model-based algorithms match the samples with the model or template. Then, a learning method is can be used to improve the algorithm. One way or another, classifiers have abig impact in face recognition. Classification methods are used in many areas like data mining, finance, signal decoding, voice recognition, natural language processing or medicine. Classification algorithms usually involve some learning supervised, Unsupervised or semi-supervised. Unsupervised learning is the most difficult approach, as there are no tagged examples. However, many face recognition applications include a tagged set of subjects. Consequently, most face recognition systems implement supervised learning methods. There are also cases where the labeled data set is small. Sometimes, the acquisition of new tagged samples can be infeasible. Therefore, semi-supervised learning is required. General Categorization of Feature classification Techniques are: Similarity based classifiers: Template Matching, Nearest Mean, Subspace Method, 1-NN, K-NN, Self-Organizing Maps(SOM). Probabilistic based classifiers: Bayesian, Logistic Classifier, Parzen Classifier. Classifiers using judgment limitations: Neural Network,Fisher Linear Discriminate (FLD), Binary Decision Tree, Perceptron, Multi-layer Perceptron, Radial Basis Network, Support Vector Machines. Combiners can be grouped in three categories according to their architecture: Figure 1.2: Feature extraction processes. Feature extraction involves several steps - dimensionality reduction, feature extraction and feature selection.This steps may overlap, and dimensionality reduction could be seen as a consequence of the feature extraction and selection algorithms. Parallel: All classifiers are executed separately. The combiner is then applied. Serial: Classifiers run one after another. Each classifier polishes previous results. Hierarchical: Classifiers are combined into a tree-like structure. 1.7 Neural Network: 1.5 Feature selection methods Feature selection algorithm’s aim is to select a subset of the extracted features that cause the smallest classification error. The importance of this error is what makes feature selection dependent to the classification method used.The most straightforward approach to this problem would be to examine A neural network is a massively parallel distributed processor that has a natural propensity for storing experiential knowledge and making it available for use. It resembles the brain in two respects: 1. Knowledge is acquired by the network through a learning process. 2. Interneuron connection strengths known as synaptic weights are used to store the knowledge. Neural networks are also referred to as neurocomputers, connectionist networks, parallel distributed processors, etc. Neural network is divided in two parts they are-Artificial Neural Network and Biological Neural Network. A neural network is an Artificial representation of human brain , that tries to simulate is learning process. A Neural Network is a system that based on models of brain structure. A neural network is a particularly equivalent distributed system that a natural partiality for store observed facts and makes it offered for use. Nodes are using for store the facts. It is layer based model that means every layer connected to each other. The layer is made by a number of units that connected to each other and the node is hold the activation energy .the neural network layer is: initial layer, middle layer and result layer. The initial layer connects to more than one middle layer and that layer sends to the data into the middle layer. Middle layer is the main layer of the NN that process the all received data and after processing send to the result to the result layer that means the result layer hold the result. Neural network is divided in two parts they are-Artificial Neural Network and Biological Neural Network. system. An ANN is a system that contains hidden layers, inputs and outputs. ANN is consisting of huge number of easy processing units that are connecting to each other and layers. An ANN consist the some functions for solving the problems. ANN are obscene electronic model based on neural structure of the brain. Artificial neuron is supposed to mimic the action of a biological neuron. ANN is used to Artificial Intelligence problem. An ANN is configured for some specific application such as pattern recognition and data classification through learning pattern. 1.7.1 Biological Neural Network The BNN is consisting of a large number of neurons and one neuron connected to other neurons. Neurons are a part of BNN. The human brain having 100 billion neurons in average. A neuron comprise in three parts: dendrites, soma and axon. Dendrites are receives the signal from neurons. Which is connected to one neuron. Axon is a very small container that transmits the signal from one neuron to each other. Fig:1.4 Structure Of the ANN ANN basically divided into two categories: Feed forward and Feed backward Network. Feed-forward networks: Feed-forward ANNs allow signals to travel one way only; from input to output. There is no feedback(loops) i. e. the output of any layer does not affect that same layer. Feedforward ANNs tend to be straight forward networks that associate inputs with outputs. They are extensively used in pattern recognition. This type of organization is also referred to as bottom-up or top-down. Feedback Network: Fig 1.3: Structure of the BNN 1.7.2 Artificial Neural Network ANN is a computerized structure of the human brain. It contains the mathematical model of biological nervous Feedback networks can have signals travelling in both directions by introducing loops in the network. Feedback networks are very powerful and can get extremely complicated. Feedback networks are dynamic ; their ‘state’ is changing continuously until they reach an equilibrium point. They remain at the equilibrium point until the input changes and a new equilibrium needs to be found. Feedback architectures are also referred to as interactive or recurrent, although the latter term is often used to denote feedback connections in single-layer organizations. 2. LITERATURE SURVEY In the recent years, artificial neural networks (ANN) were used mostly for structure intelligent computer systems related to face recognition and image processing , The most popular ANN model is the back-propagation neural network (BPNN) which can be educated using backpropagation training algorithm (BP). Different ANN models were used widely in face recognition and many times they used in combination with the above mentioned methods. Some of recent works on face recognition system based on neural network are: Hayet Boughrara ·Mohamed Chtourou · Chokri Ben Amar · Liming Chen proposed “ Facial expression recognition based on a mlp neural network using constructive training algorithm” (2014)[1]. This paper presents a constructive training algorithm for Multi Layer Perceptron (MLP) applied to facial expression recognition applications. The developed algorithm is composed by a single hidden-layer using a given number of neurons and a small number of training patterns. When the Mean Square Error MSE on the Training Data TD is not reduced to a predefined value, the number of hidden neurons grows during the neural network learning. In this paper, a constructive training algorithm for MLP neural networks has been proposed. Starting with a neural network containing a given number of hidden neurons and a small number of training patterns, the MLP neural network using the back-propagation algorithm is trained. The hidden neurons grow during the training when the MSE on the TD is not reduced to a predefined value. Input patterns are trained incrementally until all patterns of TD are selected and learned. Sheela Shankar, 2v.R Udupi Proposed “Neural Networks In Identifying Expressions In Face Recognition Systems” (2014) [2]. This paper makes a study of the neural network based approaches to identify expressions which aids in fostering face recognition systems. Multilayer Perceptron and Self Organizing Maps are the variants of neural networks, which are discussed here in detail. The paper makes a scrutinizing survey of neural network techniques to identify various expressions in human face. It was found that neural network based approach is quite robust to uniquely identify a specific expression. MLP and SOM techniques are discussed in detail. The also stated that survey can be used as a module in face recognition systems to identify a person’s expressions which are crucial to prove his identity in authentication domains. Harish Kumar Dogra1, Zohaib Hasan2, Ashish Kumar Dogra proposed “ Face expression recognition using Scaledconjugate gradient Back-Propagation algorithm” (2013)[3]. In this paper they will study the latest work done that has been done in the field of facial expression recognition and analysis. In our work they have recognized six different expressions using Cohn-kanade database and system is trained using scaled conjugate gradient back-propagation algorithm. In proposed methodology they have used MATLAB’s computer vision toolbox for face detection & cropping the images and neural network toolbox. This paper describes the different techniques that are employed in face expression recognition and analysis. With respect to machine learning techniques, they noticed a strong trend to use SVMs. Most of the teams result that they have already shown in Table 2 used SVM, such techniques have proven very popular in recent literature. But in work they have used scale conjugate gradient back propagation algorithm and they are getting overall testing accuracy up to 87.2% which is better than the as compared to the work done using SVM explained in table 2. In our future work, they can improve our recognition rate by using LBP histogram, equalization techniques & PCA techniques before training the system. Pushpaja V. Saudagare, D.S. Chaudhari proposed “ Facial Expression Recognition using Neural Network –An Overview” (2012)[4 ]. This paper reviews various techniques of facial expression recognition systems using MATLAB (neural network) toolbox. Keywords: face recognition, neural network, and facial expression recognition. In many face recognition systems the important part is face detection. The task of detecting face is complex due to its variability present across human faces including color, pose, expression, position and orientation. In this paper the automatic facial expression recognition systems are overviewed. The neural network approach is based on face recognition, feature extraction and categorization. The aproach of facial expression recognition method involve the optical flow method, active shape model technique, principle componenet analysis algorithm (PCA) and neural network technique. The approach does provide a practical solution to the problem of facial expression recognition and it can work well in constrained enviournment. S.P.Khandait , Dr. R.C.Thool, P.D.Khandait proposed “Automatic Facial Feature Extraction and Expression Recognition based on Neural Network” (2011)[5]. In this paper, an approach to the problem of automatic facial feature extraction from a still frontal posed image and classification and recognition of facial expression and hence emotion and mood of a person is presented. Feed forward back propagation neural network is used as a classifier for classifying the expressions of supplied face into seven basic categories like surprise, neutral, sad, disgust, fear, happy and angry. For face portion segmentation and localization, morphological image processing operations are used. Permanent facial features like eyebrows, eyes, mouth and nose are extracted using SUSAN edge detection operator, facial geometry, edge projection analysis. In this paper, automatic facial expression recognition (AFER) system is proposed. Machine recognition of facial expression is a big challenge even if human being recognizes it without any significant delay. The combination of SUSAN edge detector, edge projection analysis and facial geometry distance measure is best combination to locate and extract the facial feature for gray scale images in constrained environments and feed forward back-propagation neural network is used to recognize the facial expression. 100% accuracy is achieved for training sets and 95.26% accuracy is achieved for test sets of JAFFE database which is promising. Therefore in future an attempt can be made to develop hybrid approach for facial feature extraction and recognition accuracy can be further improved using same NN approach and hybrid approach such as ANFIS. An attempt can also be made for recognition of other database images or images captured from camera. Konrad Schindler a,_Luc Van Gool a,b, Beatrice de Gelder c proposed “Recognizing emotions expressed by body pose: A biologically inspired neural model”( 2008) [6]. They approach recognition of basic emotional categories from a computational perspective. In keeping with recent computational models of the visual cortex, they construct a biologically plausible hierarchy of neural detectors, which can discriminate seven basic emotional states from static views of associated body poses. The model is evaluated against human test subjects on a recent set of stimuli manufactured for research on emotional body language. They have presented a biologically inspired neural model for the form-perception of emotional body language. When presented with an image showing an expression of emotional body language, the model is able to assign it to one out of seven emotional categories (the six basic emotions + neutral). On the cognitive science side, the study has two main conclusions: firstly, although emotional body language is a rather complex phenomenon, an important part of the categorization task can be solved with low-level form processing alone, without recovering 3D pose and motion. This means that for the perception of emotional body language, 2D pose recognition, and more generally 2D processing, could play a direct role (in all likelihood, categorization would be even better when also using opticflow from the motion pathway, which we have not modeled). George Caridakis , Kostas Karpouzis, Stefanos Kollias proposed “User and context adaptive neural networks for emotion recognition” (2008) [7]. An effective approach is presented in this paper, which uses neural network architectures to both detect the need for adaptation of their knowledge, and adapt it through an efficient adaptation procedure. An experimental study with emotion datasets generate in the framework of the EC IST Humaine Network of Excellence. In this paper They proposed an extension of a neural network adaptation procedure, which caters for training from different modalities. After training and testing on a particular subject, the best-performing network is adapted using prominent samples from discourse with another subject, so as to adapt and improve its ability to generalize. Results shown here indicate that the performance of the network is improved using this approach, without the need to train a specific network for each subject, which would wipe out the nice generalization attribute of the network. Future work includes the extension of this work to include speech-related modalities, deployment on different naturalistic contexts and introduction of mechanisms to handle uncertainty in the various modalities and decide which of them would be the more robust to depend upon for co-training [3,20]. N. Fragopanagos*, J.G. Taylor proposed “Emotion recognition in human–computer interaction”( 2005)[8]. They outline the approach to construct an emotion- recognizing system. It was based on guidance from psychological studies of emotion, as well as from the nature of emotion in its interaction with attention. The aim of project was to build an automatic emotion recognition system able to exploit multimodal emotional markers such as those embedded in the voice, face and words spoken. They discussed the numerous potential applications of such a system for industry as well as in academia. They presented an artificial neural network called ANNA developed for the automatic classification of emotional states driven by a multimodal feature input. The novel feature of ANNA is the feedback attentional loop designed to exploit the attention-grabbing effect of emotional stimuli to further enhance and clarify the salient components of the input stream. They also presented the results obtained through the use of ANNA on training and esting material based on the SALAS scenario developed within the ERMIS framework. The results obtained by using ANNA indicate that there can be crucial differences between subjects as to the clues they pick up from others about the emotional states of the latter. Spiros V. Ioannou, Amaryllis T. Raouzaiou, Vasilis A. Tzouvaras, Theofilos P. Mailis, Kostas C. Karpouzis, Stefanos D. Kollias* proposed “Emotion recognition through facial expression analysis based on a neurofuzzy network” (2005) [9]. Extracting and validating emotional cues through analysis of users’ facial expressions is of high importance for improving the level of interaction in man machine communication systems. Extraction of appropriate facial features and consequent recognition of the user’s emotional state that can be robust to facial expression variations among different users is the topic of this paper. This paper describes an emotion recognition system, which combines psychological findings about emotion representation with analysis and evaluation of facial expressions. The performance of the proposed system has been investigated with experimental real data. More specifically, a neurofuzzy rule based system has been first created and used to classify facial expressions using a continuous 2D emotion space, obtaining high rates in classification and clustering of data to quadrants of the emotion representation space. Future extensions will include emotion recognition based on combined facial and gesture analysis. These can provide the means to create systems that combine analysis and synthesis of facial expressions, for providing more expressive and friendly interactions . Moreover, development of rulebased emotion recognition provides the possibility to combine the results obtained within the framework of the ERMIS project with current knowledge technologies, e.g. in implementing an MPEG-4 visual ontology for emotion recognition. E.C. Laskaria,b,∗ , G.C. Meletiouc, D.K. Tasoulisa,b, M.N. Vrahatisa,b “Studying the performance of artificial neural networks on problems related to cryptography”(2005)[10]. Cryptosystems rely on the assumption that a number of mathematical problems are computationally intractable, in the sense that they cannot be solved in polynomial time. Numerous approaches have been applied to address these problems. In this paper, they consider artificial neural networks and study their performance on approximation problems related to cryptography. In this paper, they extend previous results by studying the performance of ANNs on the same problems but in a different setting. Concerning the DLP, ANNs are used in the case where the prime number p and the primitive element modulo p vary. Therefore the basic algebraic structure (the finite field) changes. Concerning the factorization problem for the RSA, in addition to _(N), an other function is tested. Here they consider only artificial feedforward neural networks. In a future correspondence they intend to apply various other networks and learning techniques including nonmonotone neural networks [2], probabilistic neural networks[31], self-organized maps [10], recurrent networks and radial basis function networks [8]. B. Fasela;∗ , Juergen Luettinb proposed “Automatic facial expression analysis: a survey” (2002)[11]. In this survey, we introduce the most prominent automatic facial expression analysis methods and systems presented in the literature. Facial motion and deformation extraction approaches as well as classi0cation methods are discussed with respect to issues such as face normalization, facial expression dynamics and facial expression intensity, but also with regard to their robustness towards environmental changes. Although facial expressions often occur during conversations , none of the cited approaches did consider this possibility. Ifautomatic facial expression analysis systems are to be operated autonomously, current feature extraction methods have to be improved and extended with regard to robustness in natural environments as well as independence ofmanual intervention during initialization and deployment. In this survey, we have reviewed the most prominent automatic facial expression analysis methods and systems presented in the literature. Various approaches have been made towards robust facial expression recognition, applying di7erent image acquisition, analysis and classi0cation methods. They concluded this survey by summarizing recognition results and shortcomings ofcurrently employed analysis methods and proposed possible future research directions. Various applications using automatic facial expression analysis can be envisaged in the near future, fostering further interest in doing research in the 0elds of facial expression recognition, facial expression interpretation and the facial expression animation. Xudong Jiang ∗ , Alvin Harvey Kam Siew Wah proposed “Constructing andtraining feed-forwardneural networks for pattern classi$cation” (2002)[12]. A new approach of constructing andtraining neural networks for pattern classi$cation is proposed. Data clusters are generated andtrained sequentially basedon distinct local subsets of the training data. Obtainedclusters are then usedto construct a feed-forwardnetwork, which is further trainedusing standardalgorithms operating on the global training set. The network obtained using this approach e6ectively inherits the knowledge from the local training procedure before improving on its generalization ability through the subsequent global training. Various experiments demonstrate the superiority of this approach over competing methods. Keywords: Classi$cation; Neural networks; Clustering; Local andglobal training; Generalization. The resulting LGT network converges rapidly due to its inherited knowledge with good generalization ability from the global training. They believe proposed algorithm mimics the knowledge discovery approach of the human brain, which typically decomposes a complicated concept or idea into simpler subsets andlearning the details of each subset sequentially before integrating andgeneralizing all the individual pieces of knowledge acquired. The e6ectiveness of the LGT network has been amply demonstrated through its superior results in terms of accuracy andlearning speed (comparedwith other representative clustering andlearning approaches implementedin this work) on three benchmark problems operating on both synthetic andreal data sets. S. Dubuisson, F. Davoine, M. Masson* proposed “ A solution for facial expression representation and recognition”(2002)[13 ]. In this paper, they propose a feature selection process that sorts the principal components, generated by principal component analysis, in the order of their importance to solve a specific recognition task. This method provides a low-dimensional representation subspace which has been optimized to improve the classification accuracy. they focus on the problem of facial expression recognition to demonstrate this technique. They also propose a decision tree-based classifier that provides a ‘‘coarse-tofine’’ classification of new samples by successive projections onto more and more precise representation subspaces this study shows that choosing an optimal representation for faces within the principal component approach can improve the recognition task. Tests have proven quantitatively and qualitatively the interest in sorting the principal components, in the order of their importance for a recognition task, before applying LDA. They have then proposed a decision tree process that provides a ‘‘coarse to fine’’ classification, increasing the classification accuracy by 5% for the six-facial expression recognition problem. Guoqiang Zhang, B. Eddy Patuwo, Michael Y. Hu* proposed “Forecasting with artificial neural networks:The state of the art” (1997)[14]. This paper presents a state-of-the-art survey of ANN applications in forecasting. Our purpose is to provide (1) a synthesis of published research in this area, (2) insights on ANN modeling issues, and (3) the future research directions. Keywords: Neural networks; Forecasting. ANNs offer a promising alternative approach to limitations of ANNs and what they can do as well as traditional linear methods. However, while ANNs what they cannot do. Several points need to be provide a great deal of promises, they also embody a emphasized: large degree of uncertainty. There are several unsolved mysteries in this area. Since most results are · ANNs are nonlinear methods per se. For static based on limited empirical studies, the words linear processes with little disturbance, they may ‘‘seem’’ and ‘‘appear’’ are used quite commonly in not be better than linear statistical methods. the literature. Few theoretical results are established · ANNs are black-box methods. There is no explicit in this area. They believe that the future of ANN forecasting will be even brighter as more and time for training. more research efforts are devoted to this area. David Reby a, Sovan Lek b, Ioannis Dimopoulos c, Jean Joachim a, Jacques Lauga c, Ste´phane Aulagnier a proposed “ Artificial neural networks as a classification method in the behavioural sciences” (1996)[15]. The classification and recognition of individual characteristics and behaviours constitute a preliminary step and is an important objective in the behavioural sciences. Current statistical methods do not always give satisfactory results. To improve performance in this area, They present a methodology based on one of the principles of artificial neural networks: the backpropagation gradient. After summarizing the theoretical construction of the model, they describe how to parameterize a neural network using the example of the individual recognition of vocalizations of four fallow deer (Dama dama). Keywords: Mammal; Deer; Vocalization; Neural network; Classification; Modelling. The first results presented here show that performance of prediction was improved with an increasing number of neurons in the hidden layer until an asymptote was reached. Increasing this number further enhanced the risk of overfitting (Gallant, 1993). The progressive improvement of the prediction performance with the number of iterations is obvious. A limit is also quickly reached and it is not recommended to extend the training time. Indeed, time is saved by avoiding overfitting. 3. CONCLUSION Face recognition has received a great deal of attention over the last few years because of its many applications in various domains. In this paper the automatic facial expression recognition systems using neural network are overviewed. The neural network technique to detect Human Facial expression and recognize them on the basis of accuracy and computational time is discussed. The neural network approach is based on face recognition, feature extraction and categorization. The approach of facial expression recognition method involve the feature extraction of images, feature selection and then feature classification using different classification techniques like neural network. The approach does provide a practical solution to the problem of facial expression recognition. REFERENCES [1] Hayet Boughrara ·Mohamed Chtourou · Chokri Ben Amar ·Liming Chen “ Facial expression recognition based on a mlp neural network using constructive training algorithm” (2014). [2] Sheela Shankar, V.R Udupi,(2014),” Neural Networks In Identifying Expressions In Face Recognition Systems”, International Journal of Industrial Electronics and Electrical Engineering. [3] Harish Kumar Dogra1, Zohaib Hasan2, Ashish Kumar Dogra “ Face expression recognition using Scaled-conjugate gradient Back-Propagation algorithm” (2013). [4] Pushpaja V. Saudagare, D.S. 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