Abstract:
An image processing method includes creating a three-dimensional proto-model of a subject, creating a three-dimensional model of the subject by projecting to map a photographed image of the subject on the surface of the three-dimensional proto-model, displaying the three-dimensional model on the display, transforming or modifying the shape of the three-dimensional model, creating a two-dimensional modified subject image of the transformed or modified three-dimensional model, combining the two-dimensional modified subject image with the photographed image, and displaying the combined image as the modified photographed image on the display.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2004-179568, filed Jun. 17, 2004, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to image processing technology, and more particularly to the technique for modifying the image of a subject&#39;s face naturally. 
     2. Description of the Related Art 
     Various techniques for modifying the image of a person&#39;s face by image-processing have been known. Jpn. Pat. Appln. KOKAI Publication No. 9-62865 has disclosed a method of producing a natural, comfortable image of a child&#39;s face by combining the image of a man&#39;s face and the image of a woman&#39;s face. In addition, Jpn. Pat. Appln. KOKAI Publication No. 10-255066 has disclosed a method of modifying the image of a woman&#39;s face to obtain the image of a beautiful woman&#39;s face. 
     BRIEF SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention, there is provided an image processing method used in an image processing apparatus which has a display for displaying an image and modifies a photo-graphed image, the image processing method comprising: creating a three-dimensional proto-model of a subject; creating a three-dimensional model of the subject by projecting the subject portion of a photographed image on the surface of the three-dimensional proto-model and mapping the subject image onto the surface of the three-dimensional proto-model; displaying the three-dimensional model of the subject obtained by mapping on the display; transforming or modifying the shape of the three-dimensional model of the subject displayed on the display; creating a two-dimensional modified subject image by projecting the image of the transformed or modified three-dimensional model of the subject in the direction opposite to the direction in which the photographed image is projected; combining the two-dimensional modified subject image obtained by projecting the image in the opposite direction with the photographed image; and displaying the combined image as the modified photographed image on the display. 
     According to a second aspect of the present invention, there is provided an image processing apparatus which has a display for displaying an image and modifies a photographed image, the image processing apparatus comprising: a three-dimensional model creating section which creates a three-dimensional proto-model of a subject; a projection section which projects the subject portion of a photographed image to map the image onto the surface of the three-dimensional proto-model of the subject; a display section which displays on the display a three-dimensional model of the subject obtained by mapping; a transforming section which transforms or modifies the shape of the three-dimensional model of the subject displayed on the display; an inverse projection section which creates a two-dimensional modified subject image by projecting the image of the three-dimensional model of the subject transformed or modified at the transforming section in the direction opposite to the direction in which the photographed image is projected at the projection section; an image combining section which combines the two-dimensional modified subject image obtained at the inverse projection section with the photographed image; and a result-of-process display section which displays the combined image at the image combining section on the display. 
     According to a third aspect of the present invention, there is provided an image processing program which is executed on an image processing apparatus that has a display for displaying an image and modifies a photographed image, the image processing program comprising: a three-dimensional model creating step of creating a three-dimensional proto-model of a subject; a projection step of projecting the subject portion of a photographed image to map the subject image onto the surface of the three-dimensional proto-model of the subject; a displaying step of displaying on the display a three-dimensional model of the subject obtained by mapping; a transforming step of transforming or modifying the shape of the three-dimensional model of the subject displayed on the display; an inverse projection step of creating a two-dimensional modified subject image by projecting the image of the three-dimensional model of the subject transformed or modified at the transforming step in the direction opposite to the direction in which the photographed image is projected; an image combining step of combining the two-dimensional modified subject image obtained in the inverse projection step with the photographed image; and a result-of-process displaying step of displaying the image combined in the image combining step on the display. 
     According to a fourth aspect of the present invention, there is provided a recording medium with an image processing program which is executed on an image processing apparatus that has a display for displaying an image and modifies a photographed image, the recording medium with an image processing program comprising: a three-dimensional model creating step of creating a three-dimensional proto-model of a subject; a projection step of projecting the subject portion of a photographed image to map the subject image onto the surface of the three-dimensional proto-model of the subject; a displaying step of displaying on the display a three-dimensional model of the subject obtained by mapping; a transforming step of transforming or modifying the shape of the three-dimensional model of the subject displayed on the display; an inverse. projection step of creating a two-dimensional modified subject image by projecting the image of the three-dimensional model of the subject transformed or modified at the transforming step in the direction opposite to the direction in which the photographed image is projected; an image combining step of combining the two-dimensional modified subject image obtained in the inverse projection step with the photographed image; and a result-of-process displaying step of displaying the image combined in the image combining step on the display. 
     Advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
         FIG. 1  shows the configuration of an image processing apparatus to which an image processing method according to a first embodiment of the present invention is applied; 
         FIG. 2  is a flowchart to give an outline of the procedure for image processing; 
         FIG. 3  is a flowchart to help explain the procedure for a 3D model creating process; 
         FIG. 4  is a diagram to help explain the clipping of a face part of the image to be modified; 
         FIG. 5  is a diagram to help explain a pattern matching method; 
         FIG. 6  is a diagram to help explain a pattern matching method; 
         FIG. 7A  is a diagram to help explain texture mapping; 
         FIG. 7B  is a diagram to help explain texture mapping; 
         FIG. 8  is a flowchart to help explain the procedure for a modifying process; 
         FIG. 9  shows a 3D model and its copy; 
         FIG. 10  shows a lighting position adjusting screen; 
         FIG. 11  shows a 3D-model modifying screen; 
         FIG. 12  is a flowchart to help explain the procedure for a 3D-model creating process; 
         FIG. 13  shows the positional relationship between reference points, a subject, and image-taking devices; and 
         FIG. 14  shows an image photographed by the image-taking device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First Embodiment 
     In an image processing method according to a first embodiment of the present invention, a three-dimensional face image model is produced when a two-dimensional face image is modified. Then, the three-dimensional model is modified, thereby producing a two-dimensional modified face image. Hereinafter, the image processing method of the first embodiment will be explained. 
       FIG. 1  shows the configuration of an image processing apparatus  10  to which the image processing method of the first embodiment is applied. 
     The image processing apparatus  10  comprises a display section  11 , an operation input section  12 , a communication interface  13 , a temporary memory  14 , an image memory  15 , a program memory  16 , a processing section  17 , and a 3D-model memory  18 . 
     The display section  11  is a CRT or TFT liquid-crystal display which displays an image processing screen. The operation input section  12  is an input device, such as a keyboard or a mouse, which receives an operation input from the user. The communication interface  13  exchanges information, such as image data, with an external device. 
     The temporary memory  14  is a buffer memory which stores intermediate data and the like in image processing. The image memory  15  stores original images. The program memory  16  stores programs which control each function of the image processing apparatus  10 . The processing section  17  supervises the entire operation of the image processing apparatus  10 . The 3D-model memory  18  stores three-dimensional models (hereinafter, referred to as 3D models) used in image processing. 
       FIG. 2  is a flowchart to give an outline of the procedure for image processing related to the first embodiment. 
     To prepare for image processing, the user carries out a 3D-model creating process (see  FIG. 3 ) in step S 01  of  FIG. 2  for a person to be processed. 
     In step T 01  of  FIG. 3 , a person serving as an object of a 3D model is photographed from around the person, for example, the front, back, right, and left. The photographed image is stored in the temporary memory  14 . 
     Next, in step T 02 , using a three-dimensional digitizer (not shown), three-dimensional data about the person to be modified is taken in. The three-dimensional digitizer is a device which takes in three-dimensional data obtained by scanning a three-dimensional object, such as a part, a model, or the human body. Known methods of taking in three-dimensional data include a method of scanning a three-dimensional object while touching its surface and a method of scanning a three-dimensional object with light while making no contact with the surface of the object. The three-dimensional data from the three-dimensional digitizer is supplied via the communication interface  13  to the image processing apparatus  10  and then is stored in the 3D-model memory  18 . 
     Then, in step T 03 , a 3D model is created from the three-dimensional data taken in. In the 3D model created as described above, only the shape of the three-dimensional object has been reproduced. Therefore, the pattern, colors, and the like have not been given. In step T 04 , the face image of the photographed person stored in the temporary memory  14  is subjected to texture mapping onto the 3D model. In step T 05 , the completed 3D model is stored in the 3D-model memory  18 . Then, control returns. 
     To return to  FIG. 2 , in step S 02 , an image to be modified is read from the image memory  15 . In step S 03 , the face part of the image to be modified is clipped. When the face part is clipped, the outline of the face need not be clipped accurately. For instance, as shown in  FIG. 4 , an area including the face part may be roughly specified with the mouse. 
     Next, in step S 04  and step S 05 , it is determined from which direction and at what distance the created 3D model was photographed to obtain the clipped face part. To do this, the pattern matching between the image of the clipped face part and the 3D model is performed. 
       FIGS. 5 and 6  are diagrams to help explain a pattern matching method. First, 3D-model projection images of a 3D model are obtained from a plurality of viewpoints. In  FIG. 5 , 3D-model projection images A′, B′, C′ are obtained from viewpoints A, B, C. As shown in  FIG. 6 , of the 3D-model projection images A′, B′, C′, the one which matches well with the image of the clipped face part is extracted by pattern matching. In  FIG. 6 , 3D-model projection image A′ matches well with the image of the clipped face part. The pattern matching is performed repeatedly. From the result of the pattern matching, the shooting direction to the face, the shooting distance from the face, and the rotation angle of the frame are determined. 
     Then, in step S 06 , the image of the clipped face part is subjected to texture mapping onto a 3D model on the basis of the shooting direction to the face, the shooting distance from the face, and the rotation angle of a frame which have been determined.  FIG. 7A  is a top view to help explain texture mapping and  FIG. 7B  is a perspective view to help explain texture mapping. 
     Next, a modifying process ( FIG. 8 ) in step S 07  is carried out. In the modifying process, as shown in  FIG. 9 , a 3D model X and a processing 3D model Y obtained by subjecting an image to be modified Z to texture mapping onto a copy of the 3D model X are used. The processing 3D model Y is transformed, interlocking with the transformation of the 3D model X. 
     In step T 11  and step T 12  of  FIG. 8 , the 3D model X and the processing 3D model Y are displayed on the display section  11 , thereby adjusting the lighting direction. 
       FIG. 10  shows a lighting position adjusting screen. On the right of the screen, the 3D model X is displayed. On the lift of the screen, an image  20  is displayed which is obtained by photographing the processing 3D model Y from the same direction as the image to be modified Z. When a lighting position button  21  displayed in the lower part of the screen is operated, a rotation frame  25  for adjusting the lighting direction of illumination is displayed together with a mark of the sun representing illumination. Illumination can be rotated in a three-dimensional space, with three axes in the frame crossing at right angles to one another as central axes. When the lighting position changes, the shadow of the model displayed on the image  20  is transformed, interlocking with the change of the lighting position. However, the direction in which the model is shot, the shooting distance, and the rotation angle of the frame do not change. 
       FIG. 11  shows a screen for modifying the 3D model. When a modify button  22  displayed in the lower part of the screen is operated, a rectangular parallelepiped frame  26  and an outline frame  27  which enclose the 3D model X are displayed. 
     In step T 13  and step T 14  of  FIG. 8 , the 3D model X can be rotated to change its direction by dragging the vertexes of the rectangular parallelepiped frame  26 . At this time, the lighting position also changes, interlocking with the movement of the frame. Moreover, dragging the outline frame  27  enables the outline of the 3D model to be transformed. At this time, the shadow of the face also changes. 
     In step T 15  to step T 18  of  FIG. 8 , the processing 3D model Y is transformed, interlocking with the transformation of the 3D model X. Then, a two-dimensional face image is created by photographing the transformed processing 3D model Y from the same direction as the image to be modified Z (that is, in the direction opposite to the shooting). Thereafter, the created two-dimensional face image is combined with the image to be modified Z. The result of the combination is displayed on the image  20 . 
     If YES in step T 19 , that is, if the modification is continued, step T 13  to step T 18  are carried out repeatedly. If NO in step T 19 , that is, if the modification is ended, operating an end button  23  in step T 20  causes the modified image to be stored in the image memory  15  in step T 21 . Then, control returns. 
     To return to  FIG. 2 , in step S 08 , the modified image is created as a modified image of the original image to be modified Z and then is enlarged on the display section  11 . 
     Second Embodiment 
     An image processing method according to a second embodiment of the present invention differs from the first embodiment in that a plurality of image-taking devices are used to create a 3D model. The same parts as those in the first embodiment are indicated by the same reference numerals and a detailed explanation of them will be omitted. 
       FIG. 12  is a flowchart to help explain the procedure for a 3D-model creating process. The flowchart can be used in place of the 3D-model creating process of  FIG. 8 . 
     In step S 11  of  FIG. 12 , an image which includes a background including reference points whose positional relationship is known and the face part of a person to be photographed is photographed from a plurality of directions.  FIG. 13  shows the positional relationship between the reference points a, b, c, d, the subject, and the image-taking devices A, B, C. 
     In step S 12  to step S 14 , the photographed two-dimensional image is read and the positions of the reference points in the two-dimensional image are determined.  FIG. 14  shows an image photographed by the image-taking device. The positions of the reference points a, b, c, and d in the image and the relative distance between the reference points differ from those in an image taken by another image-taking device. This is because the position of the image-taking device which photographs the subject differs from the rest. Therefore, on the basis of the difference of the positions of the reference points between the photographed images, the position of each of the photographed images can be determined by triangulation. 
     In step S 15  to step S 17 , the positions of the eyes, nose, mouth, and the like, that is, the characterizing portions of the face of the photographed image, are determined for each of the photographed images. Then, on the difference of their positions between photographed images, the positions of the characterizing points of the face in the space coordinates are determined. Next, a 3D model is created by pasting curved surfaces constituting a face passing through the coordinates of a plurality of characterizing points of the face. Since in the 3D model created this way, only the shape of the three-dimensional object has been reproduced, the pattern, colors, and the like have not been given. Therefore, in step S 18 , the image of the photographed subject is subjected to texture mapping onto the 3D model. Then, in step S 19 , the completed 3D model is stored. 
     According to the first and second embodiments, use of a 3D model enables a plurality of two-dimensional images to be modified in the same manner, which makes it unnecessary to carry out separate image processes. Moreover, using a 3D model makes it possible to transform the outline naturally and easily. In addition, in modifying a 3D model, the modifier can view the resulting image immediately after it is modified. As a result, the modifier can make modifications as he or she wants to. 
     Furthermore, according to the second embodiment, since a 3D model is created on the basis of the image of the photographed subject, there is no need to provide a three-dimensional digitizer. 
     Each of the functions explained in the embodiments may be configured using hardware. Alternatively, each of the functions may be realized by loading, into a computer, programs in which each function has been written using software. Moreover, each of the functions may be configured by selectively using either software or hardware suitably. 
     Furthermore, each of the functions may be realized by loading, into a computer, programs stored in a recording medium (not shown). In the recording medium of the embodiments, any recording method may be used, provided that programs can be recorded on the recording medium by the method and the computer can read the programs from the recording medium. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.