Image Segmentation for Multiple Face Detection Using
Transcription
Image Segmentation for Multiple Face Detection Using
Volume 5, Issue 3, March 2015 ISSN: 2277 128X International Journal of Advanced Research in Computer Science and Software Engineering Research Paper Available online at: www.ijarcsse.com Special Issue: E-Technologies in Anthropology Conference Held at Bon Secours College for Women, India Image Segmentation for Multiple Face Detection Using CMY Color Model Based on Boundary Values 1 S. Saleth Shanthi, 2Dr. M. P. Indra Gandhi Research Scholar, Assistant Professor (SG), 1, 2 Department of Computer Science, Mother Teresa Women’s University, Koodaikanal, Tamil Nadu, India Abstract--- Digital Image Processing (DIP) is a multidisciplinary science that borrows principles from diverse fields such as optics, surface physics, visual psychophysics, computer science and mathematics. Some of image processing applications can be finding in: astronomy, ultrasonic imaging, remote sensing, video communications and microscopy. Face detection/recognition has attracted much attention and its research has rapidly increased in many potential applications in computer, communication and automatic access control system. Furthermore, face detection as a first step is an important part of face recognition. Since the image has lots of variations in appearance, face detection is not straightforward, such as pose variation, occlusion, image orientation, illuminating condition and others. The full face detection and gender recognition system is made up of a series of connected components. In this paper the sobel edge detection technique is applied to the image using sobel mask filtering and to find the edge of the faces. In this paper we propose a method to detect human faces in color images using CMY color model for multiple faces with multiple boundary. Keywords: RGB Image, CMY Color Model, Face Detection, Image Segmentation, Image Enhancement, Sobel Edge, Facial Features, MATLAB. I. INTRODUCTION Images are vital and integral part of everyday life. One person to person basic, image processing is a process which takes an image input and generates a modified image output. Image processing may be analog or digital. Analog image processing uses analogue electrical circuits to carry out an operation. This article is about general techniques that apply to all of them. The acquisition of images (producing the input image in the first place) is referred to as imaging. Image Processing is a method to convert an image into digital form and perform some operations on it, in order to get an enhanced image or to extract some useful information from it. Face detection is a difficult problem that consists of finding one or more faces in an image or in a video sequence under different situations. This difficulty originates from the fact that the face is not a rigid body and the different conditions under which the image or the sequence of images was acquired. The main challenges facing any face detection system typically include pose variation, the presence or absence of structural components, facial expression, occlusion, image orientation, imaging conditions, and background variations. Figure1.: Block Diagram of Face detection © 2015, IJARCSSE All Rights Reserved Page | 144 Shanthi et al., International Journal of Advanced Research in Computer Science and Software Engineering 5 (3), March- 2015, pp. 144-151 The original RGB image is got from the dataset or digital camera. To detect the face using proposed methodology. The block diagram of proposed method is in figure 1. The idea of face detection can be combined with almost every smart system as face being a biometric identifier they ensure a better secure and immune to intrusions. Biometric is the use of distinctive physical features (e.g., iris, fingerprints, face, and retina) and behavioural feature (e.g., gait, signature), called biometric identifiers, for automatic recognition of an individual. Color segmentation may be more accurate because of more information at the pixel level comparing to greyscale images. The standard Red-Green-Blue (RGB) colour representation has strongly interrelated colour components, and a number of other colour systems (e.g. HSI Hue-Saturation-Intensity) have been designed in order to exclude redundancy, determine actual object / background colours irrespectively of illumination, and obtain more stable segmentation. II. RELATED WORK The face detection system is presented to detect a face image from any background. This system is important in many applications such as face recognition to increase the speed and accuracy of recognition process that is because it deletes any undesired information. The proposed face detection system is depending on classifying the face as being either skin or non-skin [10]. An image may be defined as a two- dimensional function, f(x, y), where x and y are spatial coordinates, and the amplitude of f at any pair of coordinates(x, y) is called the intensity or gray level of the image at the point. When x, y and the amplitude values of f are all finite, discrete quantities, we call the image a digital image [1]. Some of the color models used in RGB for monitoring color, CMY model for color printing. The CMY color space is subtractive. The CMY color space can be device independent, but in major frequent they are used in reference to a special device [2]. Face Template Constructing Method: The quality of template immediate influences the effect of matching detection. To reduce the chanciness of local density of the template, the template based on the information of average face is constructed, such as average eye template and average face template [4].Face detection using color information usually consists of two main steps: localization of candidate face regions and validation of the face hypothesis using some additional information about face structure [3]. Sobel operator- it is a discrete differentiation operator, computing an approximation of the gradient of the image intensity function. At each point in the image, the result of the Sobel operator is either the corresponding gradient vector or the norm of this vector. The Sobel operator is based on convolving the image with a small, separable, and integer valued filter in horizontal and vertical direction and is therefore relatively inexpensive in terms of computations [5]. The gradient magnitude is given by: |G|=√GX2 + GY2 And its approximation is done by: |G|=|GX| + |GY|. The orientation of angle i.e. direction of gradient is given by: O = arctan(GX/GY)[7]. RGB color space is the most commonly used color space in digital images[7]. Color is a useful piece of information for skin detection. The skin detection is the most common and first approach for detecting meaningful skin color , skin color detection may avoid exhaustive search for faces in an entire image. In this step, we describe that how non skin color is rejected from an Image so that the image may contains only skin like areas, which will be our skin color segmented image for further processing [11]. It encodes colors as an additive combination of three primary colors: red(R), green (G) and blue (B). RGB Color space is often visualized as a 3D cube where R, G and B are the three perpendicular axes. One main advantage of the RGB space is its simplicity. However, it is not perceptually uniform, which means distances in the RGB space do not linearly correspond to human perception [15] [16]. In addition, RGB color space does not separate luminance and chrominance, and the R, G, and B components are highly correlated. The luminance of a given RGB pixel is a linear combination of the R, G, and B values [6]. Edge detection technique is the way in which human perceives objects and works well for images having good contrast between regions [8]. Skin classifiers are responsible for labeling the pixel whether it is skin pixel or a non-skin pixel. Piecewise linear decision boundary approach is used for human skin classification. This approach explicitly defines a decision boundary(s) of the human skin color class in the subspace of color space based on the set of sample images used for training of skin-colored and non-skin colored pixels [9]. Morphology is a broad set of operations that process images based on shapes. The operations of morphological are erosion and dilation used to smooth the object boundary without changing their respective area. The purpose of using erosion and dilation is to improve the efficiency of face detection[12]. The main work of skin color detection is to build a noise filter for removing the non-skin color pixels, so that the remaining skin color pixels will fall in the given color space. A color space is a specification of a coordinate system where each color is represented by a single value [14]. The result of the enhancement is subjected to skin segmentation, which contains the possible face candidate, followed by the skin tone percentage index method for region adjustment and noise removal. In contrast, the gray component of the enhanced image is subjected to edge detection. Results from both ends are combined and each component is analyzed for verification as a face or non-face [13]. Blobs: are the connected groups of pixels that remain at end of this stage. And hence should have head sizes (measured by number of pixels) that are relatively similar. The largest blobs should be these heads and blobs considerably smaller than the larger blobs may be safely assumed to be more ”noise”[17]. The segmented regions containing holes due to the presence of eyes and mouth are assumed to be probable segmented face regions and eliminate other segmented regions[18]. Based on the principle of threshold segmentation, we will segment the skin-likelihood images. With the original images affected by non-face regions, light, rotation angle of face and many other factors, the skinlikelihood image can’t reflect good differences between background and the objects, which thus affect the results of a follow-up partition[19]. © 2015, IJARCSSE All Rights Reserved Page | 145 Shanthi et al., International Journal of Advanced Research in Computer Science and Software Engineering 5 (3), March- 2015, pp. 144-151 III. PROPOSED METHODOLOGY A. Current Segmentation Techniques The research on image segmentation for many years has been a high degree of attention. Thousands of different segmentation techniques are present in the literature, but there is not a single method which can be considered good for different images, all methods are not equally good for a particular type of image. Thus, algorithm development for one class of image may not always be applied to other class of images. Hence, there are many challenging issues like development of a unified approach to image segmentation which can be applied to all types of images, even the selection of an appropriate technique for a specific type of image is a difficult problem. Thus, in spite of several decades of research, there is no universally accepted method for image segmentation and therefore it remains a challenging problem in image processing and computer vision. Based on different technologies, image segmentation approaches are currently divided into following categories, based on two properties of image. Detecting Discontinuities It means to partition an image based on abrupt changes in intensity, this includes image segmentation algorithms like edge detection. Detecting Similarities It means to partition an image into regions that are similar according to a set of predefined criterion. This includes image segmentation algorithms like Thresholding, region growing, region splitting and merging. B. Segmentation based on Edge Detection Sobel Operator The computation of the partial derivation in gradient may be approximated in digital images by using the Sobel operators which are shown in the masks below: Figure2 : Sobel Mask Operators This method attempts to resolve image segmentation by detecting the edges or pixels between different regions that have rapid transition in intensity are extracted and linked to form closed object boundaries. Face detection is difficult mainly due to a large component of non-rigidity and textural differences among faces. The long list of these factors include the pose, orientation, facial expression, facial sizes found in the image, luminance conditions, occlusion, structural components, gender, ethnicity of the subject, the scene and complexity of image’s background. The scene in which the face is placed ranges from a simple uniform background to highly complex backgrounds. In the latter case it is obviously more difficult to detect a face. Faces appear totally different under different lighting faces; faces closer to the camera appear larger than faces that far away from the camera. The purpose of face detection is to localize and extract the face region from the background. Face detection techniques can be roughly classified into four categories namely, Skin color model-based approaches, template matching-based approaches, feature-based approaches, and statistical model-based approaches. Usually, face detection techniques integrate some or all of the four approaches to achieve high face detection accuracy and a low false detection rate. Therefore, color segmentation becomes an important role in the area of quality control, image processing, and pattern recognition and computer vision. Face detection has been used in many applications such as biometrics, video surveillance, human computer interfaces, image database management and smart home applications. Face detection is a necessary first step in face recognition systems with the purpose of localizing and extracting the face region from the background. Detection rate and the number of false positives are important factors in evaluating face detection systems. Detection rate is the ratio between the number of faces correctly detected by the system and the actual number of faces in the image. C.COLOR MODELS To utilize color as a visual cue in multimedia, image processing, graphics and computer vision applications, an appropriate method is used for representing the color signal. The different color specification systems o color models (Color spaces or solids) address the color signals. Color spaces provide a rational method to specify order, manipulate and effectively display the object colors taken into consideration. C.1.The RGB Color Model The red-green-blue model is formed by a color cube. © 2015, IJARCSSE All Rights Reserved Page | 146 Shanthi et al., International Journal of Advanced Research in Computer Science and Software Engineering 5 (3), March- 2015, pp. 144-151 Figure3: The RGB-cube Conversion from ( R, G, B) to( X, Y, Z) is given via the chromatic ties (Xr, Y r, Zr), (Xg,, Y rg, Zg) and (Xb, Yb, Zb) of the CRTs phosphors by matrix multiplication via: Let Cr:=Xr, + Yr+ Zr . Then Xr =xr . Cr , Yr =yr .Cr and Zr =zr . Cr =(1-xr – Yr ) . Cr. This can be calculated from , , . C.2. The CMY Color Model This stands for cyan-magenta-yellow and is used for hardcopy devices. In contrast to color on the monitor, the color in printing acts subtractive and not additive. A printed color that looks red absorbs the other two components and and reflects . Thus its (internal) color is G+B=CYAN. Similarly R+B=MAGENTA and R+G=YELLOW. Thus the C-M-Y coordinates are just the complements of the R-G-B coordinates: Figure 4: CMY Color Models © 2015, IJARCSSE All Rights Reserved Page | 147 Shanthi et al., International Journal of Advanced Research in Computer Science and Software Engineering 5 (3), March- 2015, pp. 144-151 Figure 5:RGB to CMY To print a red looking color (i.e. with R-G-B coordinates (1, 0, 0)) we have to use C-M-Y values of (0, 1, 1). Note that M absorbs G, similarly Y absorbs B and hence M+Y absorbs all but R. Black ((R, G, B) = (0, 0, 0)) corresponds to (C, M, Y) = (1, 1, 1) which should in principle absorbs R, G and B. But in practice this will appear as some dark gray. So in order to be able to produce better contrast printers often use black as color. This is the CMYK-model. Its coordinates are obtained from that of the CMY-model by K: = max (C, M, Y), C:=C-K , M:=M-K and Y:=Y-K. IV. RESULT AND DISSCUSSION The proposed methodology shows the good results. The accuracy is found to be above 90%. From the existing work the accuracy, time, number of detected face and size of the image are less than the proposed work. The retrieval of images containing human faces requires detection of human faces in such images and then recognizing the face. We implemented a method that segments skin regions out and locate. We used 32 faces to test the performance of this implementation and we got 90% of accuracy. Based on the size for 20 faces the test performance is above 95%.The misses usually included regions with a similar skin likelihood values and regions that certainly were skin regions, but corresponds to other parts of the body such as arm and legs. S.No Size Total Number Number of Number of faces Number of faces Time Accuracy of Faces faces detected Partially detected not detected (%) 1 256*256*3 20 20 1 6.474915 95 2 176*286*3 32 29 3 7.356055 90 a) Original RGB Image b) CMY Model c) Filtered Image d) Edge Detected Image © 2015, IJARCSSE All Rights Reserved Page | 148 Shanthi et al., International Journal of Advanced Research in Computer Science and Software Engineering 5 (3), March- 2015, pp. 144-151 e) Binary Image f) Resultant Image with face detected a) Original RGB Image with286*176 c) Filtered Image e) Binary Image © 2015, IJARCSSE All Rights Reserved b) CMY Model d) Edge Detected Image f)Resultant Image with face detected Page | 149 Shanthi et al., International Journal of Advanced Research in Computer Science and Software Engineering 5 (3), March- 2015, pp. 144-151 V. CONCLUSION AND FUTURE WORK This paper presents a method for the detection of human face in an image. It uses simple form Skin-color models depending on the CMY values. In addition, we choose CMY because it is fast and compatible with human color perception. The overall performance of the proposed method is fast, and become faster more when number of functions becomes less which makes it useful some real-time applications. Face detection using color information usually consists of two main steps: localization of candidate face regions and validation of the face hypothesis using some additional information about face structure. We have proposed a approach to extract efficiently candidate face regions in images with varying lighting condition and in presence of complex background, with people of different ethnicities and with several persons contained within the image. While CMY fitted skin color model and hard thresholding usually fail to extract completely skin regions in complex illumination conditions, our approach manages to detect skin regions on the entire face. The aim will be to improve the face detection time i.e. the algorithm time. Further the detection of the face irrespective of the race or if the person is wearing glasses. The accuracy can also be improved. REFERENCES [1] P. Rafael C. Gonzalez and Richard E. Woods, “Digital Image Processing”, Third Edition, Pearson Education, Asia. 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