Face recognition is one of the most unobtrusive biometric techniques that can be used for access control as well as surveillance purposes. Various methods for implementing face recognition have been proposed with varying degrees of performance in different scenarios. The most common issue with effective facial biometric systems is high susceptibility of variations in the face owing to different factors like changes in pose, varying illumination, different expression, presence of outliers, noise etc. This paper explores a novel technique for face recognition by performing classification of the face images using unsupervised learning approach through K-Medoids clustering. Partitioning Around Medoids algorithm (PAM) has been used for performing K-Medoids clustering of the data. The results are suggestive of increased robustness to noise and outliers in comparison to other clustering methods. Therefore the technique can also be used to increase the overall robustness of a face recognition system and thereby increase its invariance and make it a reliably usable biometric modality
Machine learning is an application of artificial intelligence (AI) that provides systems the ability to automatically learn and improve from experience without being explicitly programmed. Machine learning focuses on the development of computer programs that can access data and use it learn for themselves.
The process of learning begins with observations or data, such as examples, direct experience, or instruction, in order to look for patterns in data and make better decisions in the future based on the examples that we provide. The primary aim is to allow the computers learn automatically without human intervention or assistance and adjust actions accordingly.
In machine learning, support vector machines (SVMs, also support-vector networks) are supervised learning models with associated learning algorithms that analyze data used for classification and regression analysis.
Machine learning is an application of artificial intelligence (AI) that provides systems the ability to automatically learn and improve from experience without being explicitly programmed. Machine learning focuses on the development of computer programs that can access data and use it learn for themselves.
The process of learning begins with observations or data, such as examples, direct experience, or instruction, in order to look for patterns in data and make better decisions in the future based on the examples that we provide. The primary aim is to allow the computers learn automatically without human intervention or assistance and adjust actions accordingly.
In machine learning, support vector machines (SVMs, also support-vector networks) are supervised learning models with associated learning algorithms that analyze data used for classification and regression analysis.
This presentation discusses about the following topics:
Physical Database Design Phase
Steps in Physical Database Design
Files and Records
Index Classification
Hash-Based Indexes
Tree Indexes
B+ Tree
Ordered Indexes
Primary Indexes
Clustering Indexes
Secondary Indexes
Indexed Sequential
Handling Missing Values for Machine Learning.pptxShamimBhuiyan8
In the machine learning model when we work with the data set sometimes we need to collect Data outside or secondary resources(ex.kaggle.com). Most of the time, various values are missing or categorical on the data set. To resolve this problem we make some ways. I think my defining steps in the presentation will help handle missing values in the data set.
** Machine Learning Training with Python: https://www.edureka.co/python **
This Edureka tutorial will provide you with a detailed and comprehensive knowledge of the Naive Bayes Classifier Algorithm in python. At the end of the video, you will learn from a demo example on Naive Bayes. Below are the topics covered in this tutorial:
1. What is Naive Bayes?
2. Bayes Theorem and its use
3. Mathematical Working of Naive Bayes
4. Step by step Programming in Naive Bayes
5. Prediction Using Naive Bayes
Check out our playlist for more videos: http://bit.ly/2taym8X
The KMeans Clustering algorithm is a process by which objects are classified into number of groups so that they are as much dissimilar as possible from one group to another, and as much similar as possible within each group. This algorithm is very useful in identifying patterns within groups and understanding the common characteristics to support decisions regarding pricing, product features, risk within certain groups, etc.
This presentation discusses about the following topics:
Physical Database Design Phase
Steps in Physical Database Design
Files and Records
Index Classification
Hash-Based Indexes
Tree Indexes
B+ Tree
Ordered Indexes
Primary Indexes
Clustering Indexes
Secondary Indexes
Indexed Sequential
Handling Missing Values for Machine Learning.pptxShamimBhuiyan8
In the machine learning model when we work with the data set sometimes we need to collect Data outside or secondary resources(ex.kaggle.com). Most of the time, various values are missing or categorical on the data set. To resolve this problem we make some ways. I think my defining steps in the presentation will help handle missing values in the data set.
** Machine Learning Training with Python: https://www.edureka.co/python **
This Edureka tutorial will provide you with a detailed and comprehensive knowledge of the Naive Bayes Classifier Algorithm in python. At the end of the video, you will learn from a demo example on Naive Bayes. Below are the topics covered in this tutorial:
1. What is Naive Bayes?
2. Bayes Theorem and its use
3. Mathematical Working of Naive Bayes
4. Step by step Programming in Naive Bayes
5. Prediction Using Naive Bayes
Check out our playlist for more videos: http://bit.ly/2taym8X
The KMeans Clustering algorithm is a process by which objects are classified into number of groups so that they are as much dissimilar as possible from one group to another, and as much similar as possible within each group. This algorithm is very useful in identifying patterns within groups and understanding the common characteristics to support decisions regarding pricing, product features, risk within certain groups, etc.
K-Medoids Clustering Using Partitioning Around Medoids for Performing Face Re...ijscmcj
Face recognition is one of the most unobtrusive biometric techniques that can be used for access control as well as surveillance purposes. Various methods for implementing face recognition have been proposed with varying degrees of performance in different scenarios. The most common issue with effective facial biometric systems is high susceptibility of variations in the face owing to different factors like changes in pose, varying illumination, different expression, presence of outliers, noise etc. This paper explores a novel technique for face recognition by performing classification of the face images using unsupervised learning approach through K-Medoids clustering. Partitioning Around Medoids algorithm (PAM) has been used for performing K-Medoids clustering of the data. The results are suggestive of increased robustness to noise and outliers in comparison to other clustering methods. Therefore the technique can also be used to increase the overall robustness of a face recognition system and thereby increase its invariance and make it a reliably usable biometric modality.
Robust face recognition by applying partitioning around medoids over eigen fa...ijcsa
An unsupervised learning methodology for robust face recognition is proposed for enhancing invariance to
various changes in the face. The area of face recognition in spite of being the most unobtrusive biometric
modality of all has encountered challenges with high performance in uncontrolled environment owing to
frequently occurring, unavoidable variations in the face. These changes may be due to noise, outliers,
changing expressions, emotions, pose, illumination, facial distractions like makeup, spectacles, hair growth
etc. Methods for dealing with these variations have been developed in the past with different success.
However the cost and time efficiency play a crucial role in implementing any methodology in real world.
This paper presents a method to integrate the technique of Partitioning Around Medoids with Eigen Faces
and Fisher Faces to improve the efficiency of face recognition considerably. The system so designed has
higher resistance towards the impact of various changes in the face and performs well in terms of success
rate, cost involved and time complexity. The methodology can therefore be used in developing highly robust
face recognition systems for real time environment.
Medoid based model for face recognition using eigen and fisher facesijscmcj
Biometric technologies have gained a remarkable impetus in high security applications. Various biometric modalities are widely being used these days. The need for unobtrusive biometric recognition can be fulfilled through Face recognition which is the most natural and non intrusive authentication system. However the vulnerability to changes owing to variations in face due to various factors like pose,
illumination, ageing, emotions, expressions etc make it necessary to have robust face recognition systems.
Various statistical models have been developed so far with varying degree of accuracy and efficiency. This
paper discusses a new approach to utilize Eigen face and Fisher face methodology by using medoid instead
of mean as a statistic in calculating the Eigen faces and Fisher faces. The method not only requires lesser training but also demonstrates better time efficiency and performance compared to the conventional method of using mean
Possibility fuzzy c means clustering for expression invariant face recognitionIJCI JOURNAL
Face being the most natural method of identification for humans is one of the most significant biometric
modalities and various methods to achieve efficient face recognition have been proposed. However the
changes in face owing to different expressions, pose, makeup, illumination, age bring about marked
variations in the facial image. These changes will inevitably occur and they can be controlled only till a
certain degree beyond which they are bound to happen and will affect the face thereby adversely impacting
the performance of any face recognition system. This paper proposes a strategy to improve the
classification methodology in face recognition by using Possibility Fuzzy C-Means Clustering (PFCM).
This clustering technique was used for face recognition due to its properties like outlier insensitivity which
make it a suitable candidate for use in designing such robust applications.PFCM is a hybridization of
Possibilistic C-Means (PCM) and Fuzzy C-Means (FCM) clustering algorithms. PFCM is a robust
clustering technique and is especially significant for its noise insensitivity. It has also resolved the
coincident clusters problem which is faced by other clustering techniques. Therefore the technique can also
be used to increase the overall robustness of a face recognition system and thereby increase its invariance
and make it a reliably usable biometric modality.
Performance Comparison of Face Recognition Using DCT Against Face Recognition...CSCJournals
In this paper, a face recognition system using simple Vector quantization (VQ) technique is proposed. Four different VQ algorithms namely LBG, KPE, KMCG and KFCG are used to generate codebooks of desired size. Euclidean distance is used as similarity measure to compare the feature vector of test image with that of trainee images. Proposed algorithms are tested on two different databases. One is Georgia Tech Face Database which contains color JPEG images, all are of different size. Another database used for experimental purpose is Indian Face Database. It contains color bitmap images. Using above VQ techniques, codebooks of different size are generated and recognition rate is calculated for each codebook size. This recognition rate is compared with the one obtained by applying DCT on image and LBG-VQ algorithm which is used as benchmark in vector quantization. Results show that KFCG outperforms other three VQ techniques and gives better recognition rate up to 85.4% for Georgia Tech Face Database and 90.66% for Indian Face Database. As no Euclidean distance computations are involved in KMCG and KFCG, they require less time to generate the codebook as compared to LBG and KPE
Multimodal authentication is one of the prime concepts in current applications of real scenario. Various
approaches have been proposed in this aspect. In this paper, an intuitive strategy is proposed as a
framework for providing more secure key in biometric security aspect. Initially the features will be
extracted through PCA by SVD from the chosen biometric patterns, then using LU factorization technique
key components will be extracted, then selected with different key sizes and then combined the selected key
components using convolution kernel method (Exponential Kronecker Product - eKP) as Context-Sensitive
Exponent Associative Memory model (CSEAM). In the similar way, the verification process will be done
and then verified with the measure MSE. This model would give better outcome when compared with SVD
factorization[1] as feature selection. The process will be computed for different key sizes and the results
will be presented.
Neural Network based Supervised Self Organizing Maps for Face Recognition ijsc
The word biometrics refers to the use of physiological or biological characteristics of human to recognize and verify the identity of an individual. Face is one of the human biometrics for passive identification with uniqueness and stability. In this manuscript we present a new face based biometric system based on neural networks supervised self organizing maps (SOM). We name our method named SOM-F. We show that the proposed SOM-F method improves the performance and robustness of recognition. We apply the proposed method to a variety of datasets and show the results.
NEURAL NETWORK BASED SUPERVISED SELF ORGANIZING MAPS FOR FACE RECOGNITIONijsc
The word biometrics refers to the use of physiological or biological characteristics of human to recognize
and verify the identity of an individual. Face is one of the human biometrics for passive identification with
uniqueness and stability. In this manuscript we present a new face based biometric system based on neural
networks supervised self organizing maps (SOM). We name our method named SOM-F. We show that the
proposed SOM-F method improves the performance and robustness of recognition. We apply the proposed
method to a variety of datasets and show the results.
Illustration of Medical Image Segmentation based on Clustering Algorithmsrahulmonikasharma
Image segmentation is the most basic and crucial process remembering the true objective to facilitate the characterization and representation of the structure of excitement for medical or basic images. Despite escalated research, segmentation remains a challenging issue because of the differing image content, cluttered objects, occlusion, non-uniform object surface, and different factors. There are numerous calculations and techniques accessible for image segmentation yet at the same time there requirements to build up an efficient, quick technique of medical image segmentation. This paper has focused on K-means and Fuzzy C means clustering algorithm to segment malaria blood samples in more accurate manner.
National Flags Recognition Based on Principal Component Analysisijtsrd
Recognizing an unknown flag in a scene is challenging due to the diversity of the data and to the complexity of the identification process. And flags are associated with geographical regions, countries and nations. But flag identification of different countries is a challenging and difficult task. Recognition of an unknown flag image in a scene is challenging due to the diversity of the data and to the complexity of the identification process. The aim of the study is to propose a feature extraction based recognition system for Myanmar's national flag. Image features are acquired from the region and state of flags which are identified by using principal component analysis PCA . PCA is a statistical approach used for reducing the number of features in National flags recognition system. Soe Moe Myint | Moe Moe Myint | Aye Aye Cho "National Flags Recognition Based on Principal Component Analysis" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26775.pdfPaper URL: https://www.ijtsrd.com/other-scientific-research-area/other/26775/national-flags-recognition-based-on-principal-component-analysis/soe-moe-myint
KPCA and Eigen Face Based Dimension Reduction Face Recognition Methodijtsrd
The practice of identifying people depending on their facial traits is known as face recognition. With rising security demands and technological advancements, obtaining information has gotten much easier. This work creates a face identification application that compares the results of several methods. The main goal is to recognize the face and retrieve information from a database. There are two main steps to it. The first stage is to discover the distinguishing elements in an image and save them. The second step is to compare it to existing photographs and provide the data associated with that image. Face detection algorithms include the Principal Component Analysis PCA mechanism and Eigen Face. To lower the complexity of image identification, we employed Kernel PCA to identify the number of components in an image and further lowered the dimension data set. Experimental results prove that if we reduced the number of dimensions of an image, then a smaller number of Eigen faces will be produced and it will take less time to identify an image. Jasdeep Singh | Kirti Bhatia | Shalini Bhadola "KPCA and Eigen-Face-Based Dimension Reduction Face Recognition Method" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-6 | Issue-5 , August 2022, URL: https://www.ijtsrd.com/papers/ijtsrd50507.pdf Paper URL: https://www.ijtsrd.com/computer-science/artificial-intelligence/50507/kpca-and-eigenfacebased-dimension-reduction-face-recognition-method/jasdeep-singh
Adversarial Multi Scale Features Learning for Person Re Identificationijtsrd
Person re identification Re ID is the task of matching a target person across different cameras, which has drawn extensive attention in computer vision and has become an essential component in the video surveillance system. Pried can be considered as a problem of image retrieval. Existing person re identification methods depend mostly on single scale appearance information. In this work, to address issues, we demonstrate the benefits of a deep model with Multi scale Feature Representation Learning MFRL using Convolutional Neural Networks CNN and Random Batch Feature Mask RBFM is proposed for pre id in this study. The RBFM is enlightened by the drop block and Batch Drop Block BDB dropout based approaches. However, great challenges are being faced in the pre id task. First, in different scenarios, appearance of the same pedestrian changes dramatically by reason of the body misalignment frequently, various background clutters, large variations of camera views and occlusion. Second, in a public space, different pedestrians wear the same or similar clothes. Therefore, the distinctions between different pedestrian images are subtle. These make the topic of pre id a huge challenge. The proposed methods are only performed in the training phase and discarded in the testing phase, thus, enhancing the effectiveness of the model. Our model achieves the state of the art on the popular benchmark datasets including Market 1501, duke mtmc re id and CUHK03. Besides, we conduct a set of ablation experiments to verify the effectiveness of the proposed methods. Mrs. D. Radhika | D. Harini | N. Kirujha | Dr. M. Duraipandiyan | M. Kavya "Adversarial Multi-Scale Features Learning for Person Re-Identification" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-4 , June 2021, URL: https://www.ijtsrd.compapers/ijtsrd42562.pdf Paper URL: https://www.ijtsrd.comengineering/computer-engineering/42562/adversarial-multiscale-features-learning-for-person-reidentification/mrs-d-radhika
An Empirical Comparison and Feature Reduction Performance Analysis of Intrusi...ijctcm
This paper reports on the empirical evaluation of five machine learning algorithm such as J48, BayesNet, OneR, NB and ZeroR using ten performance criteria: accuracy, precision, recall, F-Measure, incorrectly classified instances, kappa statistic, mean absolute error, root mean squared error, relative absolute error, root relative squared error. The aim of this paper is to find out which classifier is better in its performance for intrusion detection system. Machine Learning is one of the methods used in the intrusion detection system (IDS).Based on this study, it can be concluded that J48 decision tree is the most suitable associated algorithm than the other four algorithms. In this paper we compared the performance of Intrusion Detection System (IDS) Classifiers using seven feature reduction techniques.
A Novel DBSCAN Approach to Identify Microcalcifications in Cancer Images with...Editor IJCATR
Cancer is the most deadly disease among the human life. Breast Cancer is one of the most common cancers in this
industrialized world and it is the most common cause of cancer related death among worldwide. Many segmentation
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An Efficient Face Recognition Using Multi-Kernel Based Scale Invariant Featur...CSCJournals
Face recognition has gained significant attention in research community due to its wide range of commercial and law enforcement applications. Due to the developments in the past few decades, in the current scenario, face recognition is employing advanced feature identification techniques and matching methods. In spite of vast research done, face recognition still remains an open problem due to the challenges posed by illumination, occlusions, pose variation, scaling, etc. This paper is aimed at proposing a face recognition technique with high accuracy. It focuses on face recognition based on improved SIFT algorithm. In the proposed approach, the face features are extracted using a novel multi-kernel function (MKF) based SIFT technique. The classification is done using SVM classifier. Experimental results shows the superiority of the proposed algorithm over the SIFT technique. Evaluation of the proposed approach is done on CVL face database and experimental results shows that the proposed approach has a recognition rate of 99%.
FACIAL AGE ESTIMATION USING TRANSFER LEARNING AND BAYESIAN OPTIMIZATION BASED...sipij
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K-MEDOIDS CLUSTERING USING PARTITIONING AROUND MEDOIDS FOR PERFORMING FACE RECOGNITION
1. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 3, August 2014
K-MEDOIDS CLUSTERING USING
PARTITIONING AROUND MEDOIDS FOR
PERFORMING FACE RECOGNITION
Aruna Bhat
Department of Electrical Engineering, IIT Delhi, Hauz Khas, New Delhi
ABSTRACT
Face recognition is one of the most unobtrusive biometric techniques that can be used for access control as
well as surveillance purposes. Various methods for implementing face recognition have been proposed
with varying degrees of performance in different scenarios. The most common issue with effective facial
biometric systems is high susceptibility of variations in the face owing to different factors like changes in
pose, varying illumination, different expression, presence of outliers, noise etc. This paper explores a novel
technique for face recognition by performing classification of the face images using unsupervised learning
approach through K-Medoids clustering. Partitioning Around Medoids algorithm (PAM) has been used for
performing K-Medoids clustering of the data. The results are suggestive of increased robustness to noise
and outliers in comparison to other clustering methods. Therefore the technique can also be used to
increase the overall robustness of a face recognition system and thereby increase its invariance and make
it a reliably usable biometric modality.
KEYWORDS:
MEDOIDS, CLUSTERING, K-MEANS, K-MEDOIDS, PARTITIONING AROUND MEDOIDS
1. INTRODUCTION
Face is a natural mode of identification and recognition in humans. It comes intuitively to people
for recognising others. They have a remarkable ability to accurately identify faces irrespective of
variations caused due to changes in expression or emotion, pose, illumination, makeup, ageing,
hair growth etc. Therefore face was also included in the set of biometric modalities.
Systems which can identify or recognise individuals using their facial information were
designed [1]. One of the most useful advantages of having face as a morphological trait
for recognition purpose was its non invasiveness. It was beneficial both in terms of cost,
time and efforts to record the data for the biometric system. It altogether removed the
need of having expensive scanners which were vital for other biometric systems like
fingerprint, iris etc. It could also be used even without the knowledge of the user and
immediately found its application in surveillance.
There have been different approaches for developing an efficient face recognition system.
Various techniques for face detection, feature extraction and classification have been designed.
Viola and Jones developed the method of face detection using a combination of filters to
accurately identify face in an image [2]. The method was further enhanced by R. Lienhart and J.
Maydt [3]. However detecting a face which is the first step in face recognition is far more
DOI : 10.14810/ijscmc.2014.3301 1
2. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 3, August 2014
challenging in uncontrolled environments. The detection is followed by image processing and
feature extraction. The method of using Principal component Analysis (PCA) [4] was proposed
by M.A.Turk & A.P.Pentland [5] [6]. The face images are converted into Eigen faces which
represent the principal components of the former in the form of eigen vectors. M. Kirby & L.
Sirovich developed the Karhunen-Lo`eve procedure for the characterization of human faces [7]. It
was followed by a new system which used Fisher Linear Discriminant Analysis [8] instead of
PCA and generated Fisher faces [9] for recognition. Several variations of the methodology have
been developed based on Kernel PCA, Probabilistic and Independent Component Analysis [10].
These methods have been enhanced further and utilised in dynamic face recognition [11].
Reasonable success has also been achieved with the use of unsupervised learning methods.
Variants of clustering techniques for face recognition have been proposed. Mu-Chun Su and
Chien-Hsing Chou suggested a modified Version of the K-Means Algorithm for face recognition
[12]. Statistical Face Recognition using K-Means Iterative algorithm was proposed by Cifarelli,
Manfredi and Nieddu [13]. K-Means algorithm also has been applied in recognising variations in
faces like expression and emotions [14]. Face recognition using Fuzzy c-Means clustering and
sub-NNs was developed by Lu J, Yuan X and Yahagi T [15]. Clustering has also found its use in
dynamic and 3D face recognition applications too [16] [17]. There are many other methodologies
which have been proposed for efficient face recognition and are being improvised incessantly
[18].
The method discussed in this paper describes a novel approach of K-Medoids clustering [21] for
face recognition. The choice of using this algorithm comes from its robustness as it is not affected
by the presence of outliers or noise or extremes unlike clustering techniques based on K-Means
[19] [20]. This advantage clearly leads towards the development of sturdy face recognition
system which is invariant to the changes in pose, gait, expressions, illumination etc. Such a robust
and unobtrusive biometric system can surely be applied in real life scenarios for authentication
and surveillance.
The rest of this paper is organized as follows: Section 2 discusses the conceptual details about K-Medoids
Clustering and Partitioning Around Medoids (PAM) [21]. The proposed methodology of
applying K-Medoids Clustering to face recognition is discussed in Section 3. Experimental results
are provided in Section 4. Section 5 discusses the conclusion and the future scope.
2. OVERVIEW OF METHODOLOGY
Clustering is an unsupervised learning approach of partitioning the data set into clusters in the
absence of class labels. The members of a cluster are more similar to each other than to the
members of other clusters. One of the most fundamental and popular clustering techniques are K-Means
[19] and Fuzzy K-Means [20] clustering algorithms. K-Means clustering technique uses
the mean/centroid to represent the cluster. It divides the data set comprising of n data items into k
clusters in such a way that each one of the n data items belongs to a cluster with nearest possible
mean/centroid.
Procedure for K-Means Clustering:
Input:
k: number of clusters
D: the data set containing n items
Output:
A set of k clusters that minimizes the square-error function,
2
3. International Journal of Soft Computing, Mathematics and Control (IJSCMC), Vol. 3, No. 3, August 2014
Z = Σk
i=1 Σ ||x-ci||2 (1)
Z: the sum of the squared error for all the n data items in the data set
x: the data point in the space representing an item in cluster Ck
ci: is the centroid/mean of cluster Ck
Steps:
1: Arbitrarily choose any k data items from D. These data items represent the
initial k centroids/means.
2: Assign each of the remaining data items to the cluster that has the closest
centroid.
3: Once all the data items are assigned to a cluster, recalculate the positions of the
k
centroids.
4: Reassign each data item to the closest cluster based on the mean value of the
items in the cluster.
5: Repeat Steps 3 and 4 until the centroids no longer move.
This approach although very convenient to understand and implement has a major drawback. In
case of extreme valued data items, the distribution of data will get uneven resulting in improper
clustering. This makes K-Means clustering algorithm very sensitive to outliers and noise, thereby
reducing its performance too. K-means is also does not work quite well in discovering clusters
that have non-convex shapes or very different size. This calls for another approach to clustering
that is based on similar lines, yet is robust to outliers and noise which are bound to occur in
realistic uncontrolled environment.
K-Medoids clustering [21] is one such algorithm. Rather than using conventional mean/centroid,
it uses medoids to represent the clusters. The medoid is a statistic which represents that data
member of a data set whose average dissimilarity to all the other members of the set is minimal.
Therefore a medoid unlike mean is always a member of the data set. It represents the most
centrally located data item of the data set.
The working of K-Medoids clustering [21] algorithm is similar to K-Means clustering [19]. It
also begins with randomly selecting k data items as initial medoids to represent the k clusters. All
the other remaining items are included in a cluster which has its medoid closest to them.
Thereafter a new medoid is determined which can represent the cluster better. All the remaining
data items are yet again assigned to the clusters having closest medoid. In each iteration, the
medoids alter their location. The method minimizes the sum of the dissimilarities between each
data item and its corresponding medoid. This cycle is repeated till no medoid changes its
placement. This marks the end of the process and we have the resultant final clusters with their
medoids defined. K clusters are formed which are centred around the medoids and all the data
members are placed in the appropriate cluster based on nearest medoid.
Procedure for K-Medoid Clustering:
Input:
k: number of clusters
D: the data set containing n items
Output:
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A set of k clusters that minimizes the sum of the dissimilarities of all the objects
to
their nearest medoids.
Z = Σk
i-1 Σ |x-mi| (2)
Z: Sum of absolute error for all items in the data set
x: the data point in the space representing a data item
mi: is the medoid of cluster Ci
Steps:
1: Arbitrarily choose k data items as the initial medoids.
2: Assign each remaining data item to a cluster with the nearest medoid.
3. Randomly select a non-medoid data item and compute the total cost of
swapping old medoid data item with the currently selected non-medoid data item.
4. If the total cost of swapping is less than zero, then perform the swap operation
to generate the new set of k-medoids.
5. Repeat steps 2, 3 and 4 till the medoids stabilize their locations.
There are various approaches for performing K-Medoid Clustering. Some of them are listed
below:
I. PAM (Partitioning Around Medoids):
It was proposed in 1987 by Kaufman and Rousseeuw [21]. The above K-Medoid
clustering algorithm is based on this method.
It starts from an initial set of medoids and iteratively replaces one of the medoids by
one of the non-medoids if it improves the total distance of the resultant clustering. It
selects k representative medoid data items arbitrarily. For each pair of non-medoid data
item x and selected medoid m, the total swapping cost S is calculated. If S< 0, m is
replaced by x. Thereafter each remaining data item is assigned to cluster based on the
most similar representative medoid. This process is repeated until there is no change in
medoids.
Algorithm:
1. Use the real data items in the data set to represent the clusters.
2. Select k representative objects as medoids arbitrarily.
3. For each pair of non-medoid item xi and selected medoid mk, calculate the total
swapping cost S(ximk). For each pair of xi and mk
If S < 0, mk is replaced by xi
Assign each data item to the cluster with most similar representative item i.e.
medoid.
4. Repeat steps 2-3 until there is no change in the medoids.
II. CLARA (CLustering LARge Applications) [23] was also developed by Kaufmann &
Rousseeuw in 1990. It draws multiple samples of the data set and then applies PAM
on each sample giving a better resultant clustering. It is able to deal more efficiently
with larger data sets than PAM method.
CLARA applies sampling approach to handle large data sets. Rather than finding
medoids for the entire data set D, CLARA first draws a small sample from the data
set and then applies the PAM algorithm to generate an optimal set of medoids for the
sample. The quality of resulting medoids is measured by the average dissimilarity
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between every item in the entire data space D and the medoid of its cluster. The cost
function is defined as follows:
Cost(md,D) = Σn
i-1 d(xi, rpst(md, xi) / n
where, md is a set of selected medoids, d(a, b) is the dissimilarity between items a
and b and rpst(md, xi) returns a medoid in md which is closest to xi.
The sampling and clustering processes are repeated a pre-defined number of times.
The clustering that yields the set of medoids with the minimal cost is selected.
III. CLARANS (Randomized CLARA) was designed by Ng & Han [24]. CLARANS draws
sample of neighbours dynamically. This clustering technique mimics the graph search
problem wherein every node is a potential solution, here, a set of k medoids. If the local
optimum is found, search for a new local optimum is done with new randomly selected
node. It is more efficient and scalable than both PAM and CLARA.
3. PROPOSED METHODOLOGY
3.1. Pre-processing and Feature Extraction
Open source data sets were used to evaluate the performance of the technique. JAFFE database
[25] contains the face images with varying expressions and emotions. The face images were
segmented and processed as these preliminary steps directly impact the final results in
recognition. After determining the ROI, the features were extracted. Viola-Jones object detection
algorithm [2] was used to detect the frontal faces as well the features like eyes, nose and lips in
the respective ROI images of the faces. Viola-Jones object detection framework is a robust
technique and is known to perform accurate detection even in real time scenarios. It has been
used extensively to detect faces and face parts in the images. Therefore this algorithm was used to
extract the faces from the images and features from the former. For n face images, a two
dimensional feature vector D was created such that n rows represent each of the n faces and p
columns represent the complete feature information of every face.
3.2. Classification through Clustering
The information thus obtained from the facial images in the data set was clustered using K-Medoid
Clustering. Partitioning Around Medoids (PAM) [21] technique was used to perform the
clustering of the data space D.
The number of clusters is decided by the number of classes we have in the data set i.e. the number
of individuals whose face images are present in the data set. To find the k medoids from the
feature data space D, PAM begins with an arbitrary selection of k objects. It is followed by a
swap between a selected object Ts and a non-selected object Tn, if and only if this swap would
result in an improvement of the quality of the clustering. To measure the effect of such a swap
between Ts and Tn, PAM computes costs TCostjsn for all non-selected objects Tj. Let d(a,b)
represent the dissimilarity between items a and b. The cost TCostjsn is determined as follows
depending on which of the cases Tj is in:
I. Tj currently belongs to the cluster represented by Ci and Tj is more similar to Tj’ than Tn.
d(Tj, Tn) >= d(Tj, Tj’) where Tj’ is the second most similar medoid to Tj.
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So if Ts is replaced by Tn as a medoid, Tj would belong to the cluster
which is represented by Tj’.
The cost of the swap is:
TCostjsn = d(Tj, Tj’) – d(Tj, Ts) (3)
This always gives a non-negative TCostjsn indicating that there is a non-negative cost
incurred in replacing Ts with Tn.
II. Tj currently belongs to the cluster represented by Ci and Tj is less similar to Tj’ than Tn,
d(Tj,Tn) < d(Tj, Tj’)
So if Ts is replaced by Tn as a medoid, Tj would belong to the cluster represented by Tn.
Thus, the cost for Tj is:
TCostjsn = d(Tj’, Tn) – d(Tj, Ts) (4)
Here, TCostjsn can be positive or negative, based on whether Tj is more similar to Ts or to
Tn.
III. Tj currently belongs to a cluster other than the one represented by Ts and Tj is more
similar to Tj’ than Tn,
Let Tj’ be the medoid of that cluster. Then even if Ts is replaced by Tn, Tj would stay in
the cluster represented by Tj’.
Thus, the cost is zero:
TCostjsn = 0
(5)
IV. Tj currently belongs to a cluster represented by Tj’ and Tj is less similar to Tj’ than Tn.
Replacing Ts with Tn would cause Tn to shift to the cluster of Tn from that of Tj’.
Thus the cost involved is:
TCostjsn = d(Tj, Tn) – d(Tj, Tj’) (6)
This cost is always negative.
Combining the above four cases, the total cost for replacing Ts with Tn is given by:
TotalCostjsn = TCostjsn
(7)
Algorithm:
1. From the data space D, select k representative objects randomly and mark these as medoids.
2. Remaining data items are non-medoids.
3. Repeat till medoids stabilise/converge
for all medoid items Ts
for all non medoid items Tn
calculate the cost of swapping TCostjsn
end
end
Select s_min and n_min such that TCosts_min,n_min = Min TCostjsn
if TCosts_min,n_min < 0,
mark s_min as non medoid and n_min as medoid item.
end
4. Generate k clusters C1………….. Ck.
Once the clustering is done, all the face images are assigned to a particular cluster based on the
extent of similarity to the medoid data item of that cluster.
Thus resultant clustering also classifies the face images (in different
expressions/pose/emotions/illumination) to correct individual classes.
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4. EXPERIMENTAL RESULTS
JAFFE database [25] was used to experimentally evaluate the efficacy of the proposed method.
After performing processing and feature extraction of the face images in the data set, K-Medoid
clustering using Partitioning Around Medoids (PAM) [21] was done over the data space D which
represented the feature information from n face images.
The standard K-Means clustering [19] technique was also evaluated in order to compare the
performance of face recognition by K-Medoid and K-Means clustering.
The results with K-Medoid clustering were more robust to the outliers. It was also effective in
classifying the images reasonably even in presence of variations in the image owing to changes in
expressions and emotions. The algorithm is effective in terms of accuracy and time with medium
sized data sets and performs better than K-Means clustering technique in case of noise and
outliers. The classification precision of K-Medoid clustering using PAM was observed to be more
than that of K-Means clustering for all the data sets where outliers and noise was present. The
PAM algorithm recognised the faces with different expressions more accurately as summarised in
Table 1.
However as the data set size increases and the extent of noise and outliers are reduced, the
performance is nearly similar to standard K-Means with comparably higher computation cost
involved.
Table 1. Comparison of results K-Medoids vs K-Means Face Recognition
Data Set Clustering
(Accuracy %)
K-Means K-Medoids
Size images/individual
(varying expressions)
Noise Outliers
Set I 100 4 Y Y 65 78
100 4 Y N 70 78
100 4 N Y 72 77
100 4 N N 81 79
Set II 150 5 Y Y 66 78
150 5 Y N 70 77
150 5 N Y 72 76
150 5 N N 82 79
Set III 200 20 Y Y 68 77
200 20 Y N 72 76
200 20 N Y 72 76
200 20 N N 82 77
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80
75
70
65
60
55
K-Means K-Medoids
Set I
Set II
Set III
Figure 1. Comparison of results K-Means vs. K-Medoids (Noise: Y, Outliers: Y)
80
78
76
74
72
70
68
66
K-Means K-Medoids
Set I
Set II
Set III
Figure 2. Comparison of results K-Means vs. K-Medoids (Noise: Y, Outliers: N)
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78
77
76
75
74
73
72
71
70
69
K-Means K-Medoids
Set I
Set II
Set III
Figure 3. Comparison of results K-Means vs. K-Medoids (Noise: N, Outliers: Y)
83
82
81
80
79
78
77
76
75
74
K-Means K-Medoids
Set I
Set II
Set III
Figure 4. Comparison of results K-Means vs. K-Medoids (Noise: N, Outliers: N)
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Figure 5. An instance from the K-Medoid clustering results
The results obtained clearly depict an increase in the recognition accuracy in spite of the presence
of noise and/or outliers in the face images when the classification is done using Partioning
Around Medoids method of K-Medoid clustering. The resultant system is also reasonably
invariant to the changes in expressions as well. In comparison to K-Means clustering, the
proposed method is far more robust and usable in real scenarios where noise and outliers are
bound to be present.
5. CONCLUSIONS AND FUTURE SCOPE
As observed through the experimental analysis, the K-Medoids clustering [21] technique using
Partitioning Around Medoids (PAM) has performance comparable to that of K-Means clustering
technique in absence of noise and outliers. However its remarkable efficiency in the presence of
extreme values or outliers in the data in the data set makes it unique.
It also showcased robustness to noise and variations of expressions and emotions in the face
images. The recognition accuracy stays high without any adverse impact by aberrations that are
caused by noise and outliers.
Therefore K-Medoid clustering technique can help in designing sturdy face recognition systems
which are invariant to the changes in pose, illumination, expression, emotions, facial distractions
like make up and hair growth etc. The real time uncontrolled environment will always have some
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noise factor or variations in face. The ability of this algorithm to deal with these unavoidable
distractions in the data set encourages its use in designing robust face recognition systems.
The higher computation cost of K-Medoid clustering technique using PAM in comparison to K-Means
clustering is a concern for its application to bigger data sets. However many variants to
PAM have been developed now which are computationally as favourable as K-Means algorithm
and perform better than both PAM and K-means. We can apply such K-Medoid algorithms to
face recognition and evaluate their performance.
We may also use different facial feature extraction techniques like Eigen faces and Fisher faces
[22] etc and perform K-Medoid clustering over that data. It could also be used with various
feature detectors and descriptors like SIFT [26] and SURF [27].
ACKNOWLEDGEMENTS
The author would like to thank the faculty and staff at the Department of Electrical Engineering,
IIT Delhi for the immense guidance and help they have graciously provided.
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Authors
The author is a research scholar at Indian Institute of Technology, Hauz Khas, Delhi.
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