Patent Publication Number: US-8537155-B2

Title: Image processing apparatus and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2009-0057264, filed on Jun. 25, 2009, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     One or more embodiments relate to a three-dimensional (3D) image processing, and more particularly, to an image processing apparatus and method that may perform 3D modeling for a face of a human being. 
     2. Description of the Related Art 
     Currently, with the developments in image processing technologies, many people have interest in three dimensional (3D) modeling a face of a human being. 3D modeling of the human face may be used for a virtual reality, a computer graphic in a movie and a game, and the like. 
     For 3D modeling of the human face, a scheme of scanning spatial information associated with the human face using a laser scanner, a scheme of synthesizing color images obtained using a plurality of color cameras, and the like are generally used in the art. 
     However, the above schemes generally need a particular photographing environment or a relatively long processing time for 3D modeling, and thus there are constraints on utilization of the above schemes. 
     Accordingly, there is a need for a method that may outperform the above limitations to perform 3D modeling for a face of a human being. 
     SUMMARY 
     One or more embodiments may provide an image processing apparatus and method that may generate a three dimensional (3D) facial model of a human being in a relatively quick period of time, without a need for a particular photographing environment, and thereby enhance an efficiency of 3D modeling. 
     One or more embodiments may also provide an image processing apparatus and method that may apply characteristics such as a hair and a skin tone for 3D modeling of a human face and thereby enhance a quality of 3D modeling. 
     According to an aspect of one or more embodiments, there may be provided an image processing apparatus, including a first processor to generate a first texture by synthesizing a template texture and a facial area extracted from an input color image, a second processor to generate a first mesh model by matching both a template mesh model corresponding to the template texture and a depth image corresponding to the input color image, and a 3D model generator to generate a 3D facial model based on the first texture and the first mesh model. 
     The first processor may include an extractor to extract a characteristic point of the input color image identifying the facial area within the input color image, a first calculator to calculate a first transform function between the characteristic point of the input color image and a characteristic point of the template texture, and a texture synthesizer to generate the first texture by synthesizing the facial area and the template texture through an application of the first transform function to pixels of the facial area of the input color image. 
     The extractor may extract the characteristic point of the input color image using an active shape model. The first calculator may calculate the first transform function using a radial basis function network. 
     The texture synthesizer may adjust a color tone of the template texture using a color tone of the facial area of the input color image. 
     The second processor may include a second calculator to calculate a second transform function between a characteristic point of the template mesh model corresponding to the template texture and a characteristic point of the depth image corresponding to the input color image, and a mesh matching unit to generate the first mesh model by matching the template mesh model and the depth image through an application of the second transform function to an entire set of vertexes of the template mesh model. 
     In this case, the second calculator may calculate the second transform function using a radial basis function network. 
     The 3D model generator may extract a hair portion from the input color image, select, from a plurality of pre-stored hair models, a hair model having a hair portion similar to the extracted hair portion, and synthesize the selected hair model with the 3D facial model. 
     According to another aspect of one or more embodiments, there may be provided an image processing apparatus including a first processor to generate a first texture by synthesizing a template texture and a facial area extracted from an input color image, a second processor to transform, to a first mesh model, a template mesh model corresponding to the template texture, and a 3D model generator to generate a 3D facial model based on the first mesh model and the template texture. 
     According to still another aspect of one or more embodiments, there may be provided an image processing method, including generating a first texture by synthesizing a template texture and a facial area extracted from an input color image, generating a first mesh model by matching both a template mesh model corresponding to the template texture and a depth image corresponding to the input color image, and generating a 3D facial model based on the first texture and the first mesh model. 
     The generating of the first texture may include extracting a characteristic point of the input color image identifying the facial area within the input color image, calculating a first transform function between the characteristic point of the input color image and a characteristic point of the template texture, and generating the first texture by synthesizing the facial area and the template texture through an application of the first transform function to pixels of the facial area of the input color image. 
     The characteristic point of the input color image may be extracted using an active shape model. 
     The first transform function may be calculated using a radial basis function network. 
     The generating of the first texture may further include adjusting a color tone of the template texture using a color tone of the facial area of the input color image. 
     The generating of the first mesh model may include calculating a second transform function between a characteristic point of the template mesh model corresponding to the template texture and a characteristic point of the depth image corresponding to the input color image, and generating the first mesh model by matching the template mesh model and the depth image through an application of the second transform function to an entire set of vertexes of the template mesh model. 
     The second transform function may be calculated using a radial basis function network. 
     The generating of the 3D facial model may include extracting a hair portion from the input color image, selecting, from a plurality of pre-stored hair models, a hair model having a hair portion similar to the extracted hair portion, and synthesizing the selected hair model with the 3D facial model. 
     According to yet another aspect of one or more embodiments, there may be provided an image processing method, including generating a first texture by synthesizing a template texture and a facial area extracted from an input color image, and generating a 3D facial model based on the first texture and a template mesh model corresponding to the template texture. 
     The generating of the 3D facial model may include transforming, to a first mesh model, the template mesh model corresponding to the template texture, and generating the 3D facial model based on the first mesh model and the template texture. 
     Additional aspects, features, and/or advantages of embodiments will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. 
       These and/or other aspects and advantages will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  illustrates a configuration of an image processing apparatus according to an embodiment; 
         FIG. 2  illustrates an input color image input into an image processing apparatus according to an embodiment; 
         FIG. 3  illustrates a template texture used in an image processing apparatus according to an embodiment; 
         FIG. 4  illustrates an image with extracted characteristic points to identify a facial area in the input color image of  FIG. 2  according to an embodiment; 
         FIG. 5  illustrates an image indicating characteristic points to identify a facial area in the template texture of  FIG. 3  according to an embodiment; 
         FIG. 6  illustrates a first texture generated by synthesizing a face portion extracted from the input color image of  FIG. 2  and the template texture of  FIG. 3  according to an embodiment; 
         FIG. 7  illustrates an example of a template mesh model used in an image processing apparatus according to an embodiment; 
         FIG. 8  illustrates an example of an image of indicating characteristic points to identify a facial area in the template mesh model of  FIG. 7  according to an embodiment; 
         FIG. 9  illustrates an example of a depth image input into an image processing apparatus according to an embodiment; 
         FIG. 10  illustrates an image indicating characteristic points to identify a facial area in the depth image of  FIG. 9  according to an embodiment; 
         FIG. 11  illustrates a first mesh model generated by applying a second transform function to an entire set of vertexes of the template mesh model of  FIG. 7 , and by matching the template mesh model of  FIG. 7  and the depth image of  FIG. 9  according to an embodiment; 
         FIG. 12  illustrates an image of extracting a hair portion from the input color image of  FIG. 12  according to an embodiment; 
         FIG. 13  illustrates an example of selecting, from a hair model database, a hair model having a hair portion similar to the extracted hair portion of  FIG. 12  according to an embodiment; 
         FIG. 14  illustrates an example of an image rendered from a generated 3D facial model in a front view according to an embodiment; 
         FIG. 15  illustrates an example of an image of rendered from a generated 3D facial model in a side view according to an embodiment; and 
         FIG. 16  illustrates an image processing method according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. Embodiments are described below to explain the present disclosure by referring to the figures. 
       FIG. 1  illustrates a configuration of an image processing apparatus  100  according to an embodiment. 
     The image processing apparatus  100  may include a first processor  110 , a second processor  120 , and a three dimensional (3D) model generator  130 . 
     The first processor  110  may generate a first texture by synthesizing a template texture and a facial area extracted from an input color image. 
     According to an embodiment, the first processor  110  may include an extractor  111 , a first calculator  112 , and a texture synthesizer  113 . The extractor  111  may extract a characteristic point of the input color image identifying the facial area within the input color image. The first calculator  112  may calculate a first transform function between the characteristic point of the input color image and a characteristic point of the template texture. The texture synthesizer  113  may generate the first texture by synthesizing the facial area and the template texture through an application of the first transform function to pixels of the facial area of the input color image. 
     The extractor  111  may extract the characteristic point of the input color image using an active shape model, which is described later with reference to  FIG. 4 . 
     The first calculator  112  may calculate the first transform function using a radial basis function network, which is described later with reference to  FIGS. 5 and 6 . 
     The texture synthesizer  113  may apply the first transform function calculated by the first calculator  112  to the facial area of the input color image extracted by the extractor  111 , and synthesize the template texture and the facial area, and thereby generate the first texture. 
     In synthesizing of the first texture, a color tone of the template texture may be adjusted using information associated with a color tone of the extracted facial area and the like. 
     The second processor  120  may generate a first mesh model by matching both a template mesh model corresponding to the template texture, and a depth image corresponding to the input color image. 
     According to an embodiment, the second processor  120  may include a second calculator  121  and a mesh matching unit  122 . The second calculator  121  may calculate a second transform function between a characteristic point of the template mesh model corresponding to the template texture and a characteristic point of the depth image corresponding to the input color image. The mesh matching unit  122  may generate the first mesh model by matching the template mesh model and the depth image through an application of the second transform function to the entire set of vertexes of the template mesh model. 
     The second calculator  121  may calculate the second transform function using a radial basis function network. The mesh matching unit  122  may generate the first mesh model by applying the calculated second transform function to the entire set of vertexes of the template mesh model, which is further described in detail later with reference to  FIGS. 7 through 11 . 
     The 3D model generator  130  may generate a 3D facial model based on the first texture and the first mesh model. 
     According to an embodiment, the 3D model generator  130  may extract a hair portion from the input color image, select, from a plurality of hair models pre-stored in a storage unit  140 , a hair model having a hair portion similar to the extracted hair portion, and synthesize the selected hair model with the 3D facial model. The above process is further described in detail later with reference to  FIGS. 12 through 13 . 
     As described above, the second processor  120  may generate the first mesh model by matching the template mesh model and the depth image corresponding to the input color image. However, such a generation of the first mesh model is only an example, and thus various embodiments may be applicable. 
     For example, the template mesh model may be generated as a first mesh model having a predetermined shape. 
       FIG. 2  illustrates an input color image  200  input into an image processing apparatus according to an embodiment. 
     The input color image  200  may include a face portion  210  of a human being and a background portion  220 . A 3D facial model reflecting the face portion  210  may be generated using information associated with the face portion  210 . 
       FIG. 3  illustrates a template texture  300  used in an image processing apparatus according to an embodiment. 
     A texture may indicate information excluding geometry information from information used to generate a 3D model. For example, the texture may include surface information, color information, and the like. The texture may be used to generate the 3D model together with the geometry information, for example, a mesh model. 
     According to an embodiment, the template texture  300  used for 3D modeling of a face of a human being may be given in advance. The template texture  300  may be different from the face of the human being to be modeled. 
     For example, a facial shape, locations or shapes of eyes, eyebrows, a nose, a lip, and the like are different between the template texture  300  and an actual face of the human being. When accurately performing 3D modeling using a conventional laser scanning scheme, ears and a neck as well as the facial shape, the locations or the shapes of the eyes, the eyebrows, the nose, the lip, and the like may be accurately expressed. In one implementation embodiment, there may be a need to accurately perform modeling for the head and the face of the human being. 
     However, in one implementation embodiment, there may exist non-critical fields with respect to accurate modeling of entire head portion, for example, an avatar in a virtual reality, a character in a video game, and the like. To perform complex image processing using a special equipment, for example, a laser scanner in the above fields may waste resources. 
     According to an embodiment, a new first texture may be generated by synthesizing the face portion  210  ( FIG. 2 ) of the input color image  200  ( FIG. 2 ) and the given template texture  300 . A first mesh model may be generated by transforming a mesh model corresponding to the template texture  300  to be suitable for a depth image corresponding to the face portion  210  ( FIG. 2 ) of the input color image  200  ( FIG. 2 ). A 3D color model may be generated by mapping the first texture and the transformed first mesh model. Hereinafter, it will be further described in detail with reference to  FIG. 4 . 
       FIG. 4  illustrates a result  400  of extracting characteristic points to identify a facial area in the input color image  200  of  FIG. 2  according to an embodiment. 
     The characteristic points may be extracted using various types of algorithms. 
     For example, the characteristic points of the input color image  200  ( FIG. 2 ) may be extracted by applying an active shape model to the input color image  200  ( FIG. 2 ). 
     The result  400  shows the characteristic points, shown as red dots in  FIG. 4 , extracted by applying the active shape model to the input color image  200  ( FIG. 2 ). 
     A face outline portion  410 , an eyebrow portion  420 , an eye portion  430 , a nose portion  440 , and a lip portion  450  may be identified by the illustrated extracted characteristic points. 
     To extract the characteristic points and identify the facial area using the active shape model is only an example. Accordingly, it is understood that it is possible to extract characteristic points and identify a facial area in an input color image using various types of schemes. 
     Hereinafter, a process of synthesizing the extracted facial area and the template texture will be described with reference to  FIG. 5 . 
       FIG. 5  illustrates a result  500  of indicating characteristic points to identify a facial area in the template texture  300  of  FIG. 3  according to an embodiment. 
     The template texture  300  ( FIG. 3 ) may be pre-stored in an image processing apparatus  100  ( FIG. 1 ). Information regarding a face outline portion  510 , an eyebrow portion  520 , an eye portion  530 , a nose portion  540 , and a lip portion  550  may be pre-stored in the image processing apparatus. Accordingly, locations of characteristic points to identify the face outline portion  510 , the eyebrow portion  520 , the eye portion  530 , the nose portion  540 , and the lip portion  550  may be known. 
     According to an embodiment, the face portion  210  ( FIG. 2 ) of the input color image  200  ( FIG. 2 ) may be different from a face portion and a size, that is, a face outline portion of the template texture  300  ( FIG. 3 ). Locations or sizes of an eyebrow portion, an eye portion, a noise portion, and a lip portion may be different between the input color image  200  ( FIG. 2 ) and the template texture  300  ( FIG. 3 ). 
     Accordingly, the face area extracted from the input color image  200  ( FIG. 2 ) may be transformed and thereby be synthesized with the template texture  300  ( FIG. 3 ). For the above transformation, a first transform function may be calculated. 
     The first transform function may represent a transformation relationship between the characteristic points extracted in the input color image  200  ( FIG. 2 ), and the characteristic points existing in the template texture  300  ( FIG. 3 ). 
     When the first transform function is calculated, the extracted face portion  210  ( FIG. 2 ) may be synthesized within the template texture  300  ( FIG. 3 ) by applying the first transform function to the entire face portion  210  ( FIG. 2 ). 
     The first transform function may be calculated using a radial basis function network. 
     A radial function denotes a function to calculate a relationship by calculating a distance from a particular center with respect to a plurality points and thus the radial function may express a circular shape such as Gaussian. 
     A network to map an input value x and an output value y by using the above radial function as a basis may be referred to as the radio basis function network, which may be expressed, for example, by the following Equation 1 below. 
     
       
         
           
             
               
                 
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                             w 
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                   Equation 
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                   1 
                 
               
             
           
         
       
     
     In the above Equation 1, w i  denotes two dimensional (2D) image coordinates and 3D vertex coordinates that are detected in deformation of a texture and a mesh. 
     Here, w i  may be calculated using a known x i  value and y i  value. Here, x i  denotes a characteristic point in a color/depth image and y i  denotes a characteristic point in the texture/mesh. 
     A y value may be obtained by inputting a distance value between xi and x into a radial basis function, and by multiplying each weight wi thereto and then calculating a total sum. 
     In the basic radial basis function network, the p(x) term of Equation 1 may not exist. The term p(x) in Equation 1, is a polynomial term which may be an added term to improve the deformation. In this case, a result of inputting the x value into a polynomial function may be used. 
     Examples of the radial basis function φ may include various types of functions. Here, the radial basis function φ may be a thin plate spline function used for deformation of the image and the mesh. 
     The entire face portion  210  ( FIG. 2 ) of the input color image  200  ( FIG. 2 ) may be synthesized with the template texture  300  ( FIG. 3 ) using the first transform function ƒ(x) obtained through the above scheme. 
       FIG. 6  illustrates a first texture  600  generated by synthesizing the face portion  210  ( FIG. 2 ) extracted in the input color image  200  of  FIG. 2  and the template texture  300  of  FIG. 3  according to an embodiment. 
     In the first texture  600 , a face portion is obtained from the input color image  200  ( FIG. 2 ) and the remaining portions are obtained from the template texture  300  ( FIG. 3 ). 
     In the first texture  600 , shapes of major face portions, for example, an eyebrow portion, an eye portion, a nose portion, a lip portion, and the like may be similar to corresponding portions of the input color image  200 , however, there may exist differences in minute shapes or relative locations. 
     In this case, a color tone, a skin pattern, and the like of the face portion  210  ( FIG. 2 ) of the input color image  200  ( FIG. 2 ) may be applied to the entire skin of the template texture  300 . Through this, since the entire skin tone of the first texture  600  may look uniform, a quality of a 3D facial model may be enhanced. 
     The template texture  300  ( FIG. 3 ) may be stored together with a template mesh model corresponding to the template texture  300  ( FIG. 3 ). Hereinafter, the template mesh model will be described with reference to  FIG. 7 . 
       FIG. 7  illustrates a template mesh model  700  used in an image processing apparatus according to an embodiment. 
     3D geometry information may be classified into a mesh-based scheme and a point-based scheme. Herein, the 3D geometry information may be the mesh-based scheme. Meshes may be expressed based on a triangular unit. Each triangle may be referred to as a vertex. An example of one of the many vertexes in  FIG. 7  is shown by vertex  710 . 
     Each of vertexes may be mapped with a particular color value in the template texture  300  ( FIG. 3 ). When color values of the template texture  300  ( FIG. 3 ) are applied to the vertexes of the template mesh model  700 , a 3D facial model may be generated. 
     The 3D facial model may be generated by applying the synthesized first texture  600  ( FIG. 6 ) to the template mesh model  700 . In this case, a facial shape of a particular human being may be modeled into a head shape different from a head shape of the particular human being by providing various template mesh models. 
     Various types of applications may be used. For example, in the industry fields of a video game, a virtual reality, a plastic surgery simulation, and the like, a 3D facial model may be generated by mapping a face of a particular human being and a head shape of a different human being. 
     Another 3D facial model may be generated by transforming the template mesh model  700  to be in a random shape, and by applying the transformed template mesh model  700  to the first texture  600  ( FIG. 2 ). 
     Also, the 3D facial model may be generated to have the same head shape as the face of the color input image  200  ( FIG. 2 ) used to generate the first texture  600  ( FIG. 6 ). It will be described hereinafter with reference to  FIG. 8 . 
       FIG. 8  illustrates a result  800  of indicating characteristic points to identify a facial area in the template mesh model  700  of  FIG. 7  according to an embodiment. 
     Like the template texture  300  ( FIG. 3 ), information regarding the characteristic points to identify a face outline portion  810 , an eyebrow portion  820 , an eye portion  830 , a nose portion  840 , and a lip portion  850  may be given in the template mesh model  700  ( FIG. 7 ). 
     When transforming the template mesh model  700  ( FIG. 7 ) to be in a random face shape, that is, a head shape, or to be in a particular head shape corresponding to the input color image  200  ( FIG. 2 ), the characteristic points of the template mesh model  700  ( FIG. 7 ) may be used. 
     In this case, there is a need to calculate a second transform function to transform the characteristics points of the template mesh model  700  ( FIG. 7 ) to characteristic points of another head shape. 
     In one implementation embodiment, the second transform function may be given in advance. Here, when the template mesh model is transformed to be in the head shape corresponding to the input color image  200  ( FIG. 2 ), there is a need for a separate calculation scheme. 
       FIG. 9  illustrates a depth image  900  input into an image processing apparatus according to an embodiment. 
     The depth image  900  may match the input color image  200  of  FIG. 2 . Due to a degraded hardware performance of a depth camera, a depth image obtained with respect to a particular object may have a relatively low resolution in comparison to a color image obtained with respect to the particular object. 
     There may exist minute differences in a relative location, a viewpoint, and the like, between a camera lens and the particular object. Therefore, there is a need for a process of accurately matching the minute differences using an image processing method. 
     The depth image  200  ( FIG. 2 ) may match the color input image  200  ( FIG. 2 ) through the above process. 
     When the depth image  900  and the color image  200  ( FIG. 2 ) match each other, information associated with the characteristic points extracted from the input color image  200  ( FIG. 2 ) may be applicable to the depth image  900  as is. Accordingly, there is no need to calculate the characteristic points of the depth image  900 . 
     Accordingly, the depth image  900  may be immediately separated into a face portion  910  and a background portion  920 . 
       FIG. 10  illustrates a result  1000  of indicating characteristic points to identify a facial area in the depth image  900  of  FIG. 9  according to an embodiment. 
     The characteristic points may identify a face outline portion  1010 , an eyebrow portion  1020 , an eye portion  1030 , a nose portion  1040 , and a lip portion  1050 , respectively, in the depth image  900  ( FIG. 9 ). 
     A second transform function between the characteristic points of the template mesh model  700  ( FIG. 7 ) shown in  FIG. 8 , and the characteristic points of the depth image  900  ( FIG. 9 ) shown in  FIG. 10  may be calculated. 
     In this case, the second transform function may be calculated using a radial basis function network. 
     When the calculated second transform function is applied to the entire set of vertexes of the template mesh model  700  ( FIG. 7 ), a first mesh model may be generated to have the same head shape as the depth image  900  ( FIG. 9 ) and the input color image  200  ( FIG. 2 ). 
       FIG. 11  illustrates a first mesh model  1100  generated by applying a second transform function to the entire set of vertexes of the template mesh model  700  of  FIG. 7 , and matching the template mesh model  700  ( FIG. 7 ) and the depth image  900  of  FIG. 9  according to an embodiment. 
     The first mesh model  1100  may have the same head shape as the depth image  900  ( FIG. 9 ) and the input color image  200  ( FIG. 2 ). Accordingly, when the generated first texture  600  ( FIG. 6 ) is applied to the first mesh model  1100 , a 3D facial model similar to the input color image  200  may be generated. 
     Here, a hair portion of the first texture  600  ( FIG. 6 ) reflects hair of the original template texture  300  ( FIG. 3 ) as is. Accordingly, a hair portion of the generated 3D facial model may be different from the input color image  200  ( FIG. 2 ). 
     The hair portion may be separately corrected, which will be described with reference to  FIGS. 12 and 13 . 
       FIG. 12  illustrates a result  1200  of extracting a hair portion  1210  from the input color image  200  of  FIG. 2  according to an embodiment. 
     The hair portion  1210  may be extracted from the input color image  200  ( FIG. 2 ) using various types of schemes. 
     The input color image  200  ( FIG. 2 ) may be separated into the hair portion  1210  and a background portion  1220  by performing high pass filtering (HPF) for the input color image  200  ( FIG. 2 ). 
     Also, the hair portion  1210  may be extracted using hue values of pixels constituting the input color image  200  ( FIG. 2 ). 
     A hair model having a hair portion most similar to the extracted hair portion  1210  may be retrieved from a hair model database. 
       FIG. 13  illustrates an example of selecting, from a hair model database  1300 , a hair model  1310  having a hair portion similar to the extracted hair portion  1210  of  FIG. 12  according to an embodiment. 
     The hair model database  1300  may store various 3D hair models. 
     The hair model  1310  having the hair portion most similar to the extracted hair portion  1210  may be selected from the hair model database  1300 . 
     A 3D facial model with even a hair portion similar to the color input image  200  ( FIG. 2 ) may be generated by reflecting the selected hair model  1310  in the first texture  600  ( FIG. 6 ) and the first mesh model  1100  ( FIG. 11 ). 
       FIG. 14  illustrates a result  1400  of rendering a generated 3D facial model in a front view according to an embodiment. 
     Referring to  FIG. 14 , a face portion  1410  may be generated based on the first texture  600  ( FIG. 6 ) and the first mesh model  1100  ( FIG. 11 ). A hair portion  1420  may be generated based on the selected hair model  1310  of  FIG. 13 . 
       FIG. 15  illustrates a result  1500  of rendering a generated 3D facial model in a side view according to an embodiment. 
       FIG. 16  illustrates an image processing method according to an embodiment. 
     In operation S 1610 , the face portion  210  ( FIG. 2 ) may be extracted from the input color image  200  ( FIG. 2 ). A process of extracting characteristic points is described above with reference to  FIGS. 2 and 4 . 
     In operation S 1620 , referring to  FIGS. 2 ,  3 , and  6 , the first texture  600  may be generated by synthesizing the extracted face portion  210  and the template texture  300 . Here, a process of calculating the first transform function to transform the extracted face portion  210  to the face portion of the template texture  300  is described above with reference to  FIGS. 2 through 4 , and the above Equation 1. 
     In operation S 1630 , referring to  FIGS. 2 ,  3 ,  7 ,  9  and  11 , the template mesh model  700  corresponding to the template texture  300  may be transformed. 
     In this case, the template mesh model  700  may be transformed to be in a random head shape. 
     To transform the template mesh model  700  to be in the same head shape as the input color image  200 , the first mesh model  1100  may be generated by matching the template mesh model  700  and the depth image  900  that is matched with the input color image  200 . 
     According to an embodiment, while matching the template mesh model  700  and the matched depth image  900  of the input color image  200 , a process of calculating the second transform function between the characteristic points of the template mesh model  700  and the characteristic points of the depth image  900 , and applying the second transform function to the entire vertexes of the template mesh model  700  may be performed. The above process is described with reference to  FIGS. 10 and 11 . 
     Through the above process, the 3D facial model may be generated using the first texture  600  and the first mesh model  1100 . 
     According to another embodiment, in operation S 1640 , the hair portion  1210  may be extracted from the input color image  200 , and the hair model  1310  having a hair portion most similar to the extracted hair portion  1210  may be retrieved from the hair model database  1300 . The retrieved hair model  1310  may be used to generate the 3D facial model together with the first texture  600  ( FIG. 6 ) and the first mesh model  1100 . The above process is described above with reference to  FIGS. 12 and 13 . 
     In operation S 1650 , the 3D facial model may be generated. In one implementation embodiment, the generated 3D facial model may be corrected by performing post-processing. 
     In operation S 1660 , the 3D facial model generated by modeling the input color image  200  ( FIG. 2 ) may be rendered. It is described above with reference to  FIGS. 14 and 15 . 
     The image processing method according to the above-described embodiments may also be implemented through computer readable code/instructions in/on a medium, e.g., a computer readable medium, to control at least one processing element to implement any above described embodiment. The medium can correspond to medium/media permitting the storing or transmission of the computer readable code. 
     The computer readable code can be recorded or transferred on a medium in a variety of ways, with examples of the medium including recording media, such as magnetic storage media (e.g., ROM, floppy disks, hard disks, etc.) and optical recording media (e.g., CD-ROMs, or DVDs), and transmission media. The media may also be a distributed network, so that the computer readable code is stored or transferred and executed in a distributed fashion. Still further, as only an example, the processing element could include a processor or a computer processor, and processing elements may be distributed or included in a single device. 
     In addition to the above described embodiments, example embodiments can also be implemented as hardware, e.g., at least one hardware based processing unit including at least one processor capable of implementing any above described embodiment. 
     Although a few embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined by the claims and their equivalents.