Abstract:
The present invention is a system and method for increasing the value of the audio-visual entertainment systems, such as karaoke, by simulating a virtual stage environment and enhancing the user&#39;s facial image in a continuous video input, automatically, dynamically and in real-time. The present invention is named Enhanced Virtual Karaoke (EVIKA). The EVIKA system consists of two major modules, the facial image enhancement module and the virtual stage simulation module. The facial image enhancement module augments the user&#39;s image using the embedded Facial Enhancement Technology (F.E.T.) in real-time. The virtual stage simulation module constructs a virtual stage in the display by augmenting the environmental image. The EVIKA puts the user&#39;s enhanced body image into the dynamic background, which changes according to the user&#39;s arbitrary motion. During the entire process, the user can interact with the system and select and interact with the virtual objects on the screen. The capability of real-time execution of the EVIKA system even with complex backgrounds enables the user to experience a whole new live virtual entertainment environment experience, which was not possible before.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is entitled to the benefit of Provisional Patent Application Ser. No. 60/399,542, filed Jul. 30, 2002. 

   BACKGROUND OF THE INVENTION—FIELD OF THE INVENTION 
   The present invention relates to a system and method for enhancing the audio-visual entertainment environment, such as karaoke, by simulating a virtual stage environment and enhancing facial images by superimposing virtual objects on top of the continuous  2 D human face image automatically, dynamically and in real-time, using a facial feature enhancement technology (FET). This invention provides a dynamic and virtual background where the user&#39;s body image can be placed and changed according to the user&#39;s arbitrary movement. 
   BACKGROUND OF THE INVENTION 
   Karaoke, noraebang, (a kind of Korean sing-along entertainment system similar to karaoke), and other sing-along systems are a few examples of popular audio-visual entertainment systems. Although there are various types of karaoke systems, they traditionally consist of a microphone, music/sound system, video display system, controlling system, lighting, and several other peripherals. In a traditional karaoke system, a user selects the song he/she wants to sing by pressing buttons on the controlling device. The video display system usually has a looping video screen and the lyrics of the song at the bottom of the screen to help the user follow the music. Although the karaoke system is an interesting entertainment source, especially for its fascinating sound and music, this looping video screen is a boring part of the system to some people. 
   In order to make the video screen more interesting, there have been attempts to apply some image processing techniques, such as putting the singer&#39;s face image into a specific section of a background image. There have also been attempts to put the user&#39;s face image into printed materials. 
   European Patent Application EP0782338 of Sawa-gun, Gunma-ken et al. disclosed an approach to display a video image of a singer on the monitor of the system, in order to improve the quality of a “karaoke” system. 
   U.S. Pat. No. 6,400,374 of Lanier disclosed a system for superimposing a foreground image like a human head with face to the background image. 
   However, in the previous attempts, most approaches used a predefined static background or designated region, such as rectangular bounding box, in a video loop. In the case of using a predefined static background, the background cannot be interactively controlled by the user in real-time. Although the user moves, the background image is not able to respond to the user&#39;s arbitrary motion. On the other hand, in the case of using the rectangular bounding box, although it might be possible to make the bounding box move along with the user&#39;s head motion, the user does not seem to appear to be fully immersed into the background image. The superimposition of images is also limited by the granularity of face size rather than facial feature level. In these approaches, the human face image essentially becomes the superimposing object to the background templates or pre-handled video image sequences. However, we can also superimpose other virtual objects onto the human face image, thus further increasing the level of amusement. Human facial features can provide the useful local coordinate information within the face image in order to augment the human facial image. 
   Thus it is possible to greatly enhance the users&#39; experience by using various computer vision and image processing technologies with the help of a video camera. 
   Advantage of the Invention 
   Unlike these previous attempts, our system, Enhanced Virtual Karaoke (EVIKA), uses a dynamic background, which can change in real-time according to the user&#39;s arbitrary motion. The user&#39;s image also appears to be fully immersed into the background, and the position of the user&#39;s image changes in any part of the background image as the user moves or dances while singing. 
   Another interesting feature of the dynamic background in the EVIKA system is that the user&#39;s image disappears behind the background if the user stands still. This adds an interesting and amusing value to the system, in which the user has to dance as long as the person wants to see himself on the screen. This feature can be utilized as a method to entice the user to participate in dancing. This also helps to encourage a group of users to participate. 
   In prior attempts at simulating the virtual reality environment, a blue background was frequently used. However, in the EVIKA system, any arbitrary background can be used, and no specific control of the actual environment is required. This means that the EVIKA system can be installed in any pre-existing commercial environment without destroying the pre-existing environment and re-installing a new expensive physical environment. The only condition might be that the environment should have enough lighting so that the image-capturing system and processing system in EVIKA can detect the face and facial features. 
   The background can also be aesthetically augmented for decoration by the virtual objects. Virtual musical instrument images, such as guitars, pianos, and drums, can be added to the background. The individual instrument images can be attached to the user&#39;s image, and the instrument images can move along with the user&#39;s movement. The user can also play the virtual instrument by watching the instrument on screen and moving his hands around the position of the virtual instrument. This allows the user to participate further in the experience and therefore increases enjoyment. 
   The EVIKA system uses the embedded FET system, which not only detects the face and facial features efficiently, but also superimposes virtual objects on top of the user&#39;s face and facial features in real-time. This facial enhancement is another valuable feature addition to the audio-visual entertainment system along with the fully immersed body image into the dynamic virtual background. The superimposed objects move along with the user&#39;s arbitrary motion in real-time. The user can change the virtual objects through a touch-free selection process. This process is achieved through tracking the user&#39;s hand motion in real-time. The virtual objects can be fanciful sunglasses, hat, hair wear, necklace, rings, beard, mustache, or anything else that can be attached to the human facial image. This whole process can transfigure the singer/dancer into a famous rock-star or celebrity on a stage and provides the user a new and exciting experience. 
   SUMMARY 
   The present invention processes a sequence of images received from an image-capturing device, such as a camera, and simulates a virtual environment through a display device. The implementation steps in the EVIKA system are as follows. 
   The EVIKA system is composed of two main modules, the facial image enhancement module and the virtual stage simulation module. The facial image enhancement module passes the captured continuous input video images to the embedded FET system in order to enhance the user&#39;s facial image, such as superimposing an image of a pair of sunglasses onto the image of the user&#39;s eyes. The FET system is a system for enhancing facial images in a continuous video by superimposing virtual objects onto the facial images automatically, dynamically and in real-time. The details of the FET system can be found in the following provisional patent application, R. Sharma and N. Jung, Method and System for Real-time Facial Image Enhancement, U.S. Provisional Patent. Application No. 60/394,324, Jul. 8, 2002. The superimposed objects move along with the user&#39;s arbitrary motion dynamically in real-time. The FET system detects and tracks the face and facial features, such as eyes, nose, and mouth, and finally it superimposes the face image with the selected virtual objects. 
   The virtual objects are selected by the user in real-time through the touch-free user interaction interface during the entire session. In a provisional patent application filed by R. Sharma, N. Krahnstoever, and E. Schapira, Method and System for Detecting Conscious Hand Movement Patterns and Computer-generated Visual Feedback for Facilitating Human-computer Interaction, U.S. Provisional Patent filed. Apr. 2, 2002, the authors describe a method and system for touch-free user interaction. After the FET system superimposes the virtual object, which is selected by the user in real-time on to the facial image, the facial image is enhanced and is ready to be combined with the simulated virtual background images. The enhanced facial image provides an interesting and entertaining view to the user and surrounding people. 
   The virtual stage simulation module is concerned about constructing the virtual stage. Customized virtual background images are created and prepared offline. The music clips are also stored in the digital music box. They are loaded at the beginning of the session and can be selected by the touch-free user interaction in real-time. A touch-free user interaction tool enables the user to select the music and the virtual background. When a new background and a new song are selected, they are combined to simulate the virtual stage. By adding the virtual objects images to the background the system produces an interesting and exciting environment. Through this virtual environment, the user is able to experience what was not possible before. 
   During or after the selection process, if the user moves, the background also changes dynamically. This dynamically changing background also contributes to the simulation of the virtual stage. 
   After the facial image enhancement module and the virtual stage simulation module finish the process, the images are combined. This creates the final virtual audio-visual entertainment system environment. 

   
     DRAWINGS—FIGURES 
     FIG.  1 —Figure of the EVIKA System and User Interaction 
     FIG.  2 —Block Diagram for Overall View and Modules of the EVIKA system 
     FIG.  3 —Block Diagram for Facial Image Enhancement Module 
     FIG.  4 —Block Diagram for Virtual Stage Simulation Module 
     FIG.  5 —Virtual Stage Simulation by Composing Multiple Augmented Images 
     FIG.  6 —Dynamic Background of Virtual Stage Simulation Modules 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows the overall system that provides the hardware and application context for the present invention. In the exemplary embodiment shown in  FIG. 1 , the hardware components of the system consist of an image capturing device  100 , means for displaying output  101 , means for processing and controlling  102 , a sound system  103 , a microphone  105 , and an optional lighting system  106 . The image of the user is superimposed with a hat image  107 , sunglasses image  108 , or any other predefined virtual object images. The background is also augmented to provide a virtual reality environment for the user. For this embodiment, a virtual platform image  112  and spotlight image  109  were added to the background. Musical instrument type virtual objects, such as a virtual piano image or a virtual guitar image  111 , can also be added to the scene in order to simulate a stage environment. The user&#39;s body blends into the background, and the background dynamically changes according to the user&#39;s motion in real-time. The user can select different virtual objects by a motion-based, touch-free interaction  115  process. The image-capturing devices automatically adjust to the height of the viewing volume according to the height of the user. The user&#39;s face is being tracked in real-time and augmented by virtual object superimposition  204 . 
   In this exemplary embodiment shown in  FIG. 1 , a camera, such as the Sony EVI-D30, and frame grabber, such as the Matrox Meteor II frame grabber, may be used as the image-capturing device  100  if dynamic control is needed. A firewire camera, such as the Pyro 1394 web cam by ADS technologies or iBOT FireWire Desktop Video Camera by OrangeMicro, or a USB camera, such as the QuickCam Pro 3000 by Logitech, may be used as the image capturing devices if dynamic control of the field of view is not needed. A large display screen, such as the Sony LCD projection data monitor model number KL-X9200U, may be used for the means for displaying output  101  in the exemplary embodiment. A computer system, such as the Dell Precision 420, with processors, such as the dual Pentium 864 Mhz microprocessors, and with memory, such as the Samsung 512 MB DRAM, may be used as the means for processing and controlling  102  in the exemplary embodiment. Any appropriate sound system and wired or wireless microphone can be used for the invention. In the exemplary embodiment, the Harman/Kardon multimedia speaker system may be used as the sounding system  103  and audio-technica model ATW-R03 as the microphone  105 . Any appropriate lighting  106 , in which the user&#39;s face image is recognizable by the image capturing device  100  and means for processing and controlling  102 , can be used for the invention. The processing software may be written in a high level programming language, such as C++, and a compiler, such as Microsoft Visual C++, may be used for the compilation in the exemplary embodiment. Image creation and modification software, such as Adobe Photoshop, may be used for the virtual object and stage creation and preparation in the exemplary embodiment. 
     FIG. 2  shows the two main modules in the EVIKA system and block diagram and how the invention simulates the virtual audio-visual entertainment system environment. 
   The facial image enhancement module  200  uses the embedded FET system  203  in order to enhance the participant&#39;s facial image. The FET system  203  is a system for enhancing facial images in a continuous video stream by superimposing virtual objects onto the facial images automatically, dynamically and in real-time. The details of the FET system  203  can be found in the R. Sharma and N. Jung, Method and System for Real-time Facial Image Enhancement, U.S. Provisional Patent. Application No. 60/394,324, Jul. 8, 2002. The image-capturing device captures the video input images  202  and feeds them into the FET system  203 . After the FET system  203  superimposes  204  the virtual object, which is selected  206  by the user in real-time, onto the facial image, such as the image for eyes, nose, and mouth, the facial image is enhanced. For example, the image of the user&#39;s eyes can be superimposed by a pair of sunglasses image  108 , as described in the FET system. Thus, the facial image enhancement by the facial image enhancement module  200  can be accomplished at the level of facial features in the exemplary embodiment. The enhanced facial image  205  provides an interesting and entertaining spectacle to the user and surrounding people. 
   The virtual stage simulation module  201  is concerned with constructing the virtual stage  208 . A touch-free user interaction  115  tool enables the user to select the music  207  and the virtual background  401 . In the exemplary embodiment shown in  FIG. 2 , the method and system as described in a provisional patent application by R. Sharma, N. Krahnstoever, and E. Schapira, Method and System for Detecting Conscious Hand Movement Patterns and Computer-generated Visual Feedback for Facilitating Human-computer Interaction, U.S. Provisional Patent filed. Apr. 2, 2002, may be used for the touch-free user interaction. Depending on the user selection, the virtual stage is simulated  208  to provide an interesting and exciting environment. Through this virtual environment, the user is able to experience what was not possible in the normal life before. 
   After the facial image enhancement module  200  and the virtual stage simulation module  201  finish the process, the images are combined and create the final virtual audio-visual entertainment environment  209 . 
     FIG. 3  shows the details of the facial image enhancement module. The image-capturing device captures the input video images in the beginning of this module. The primary input is the video input images  202  in the EVIKA system. 
   Below is the list of the performance requirements for the FET system  203  for the continuous real-time input video images.
         a. The face detection, facial feature detection, face tracking, hand tracking, and superimposition of the objects must run together in such a way that real-time processing is possible.   b. The system has to be adaptive to the variation in continuous images from frame to frame, where the image conditions from frame to frame could be different.   c. The user has to be able to use the system naturally without any cumbersome initializing of the system manually. In another words, the system has to automatically initialize itself.   d. The usage of threshold and fixed size templates has to be avoided.   e. The system has to work with not only high-resolution images but also low-resolution images and adapt to changes in resolution.   f. The system has to be tolerant to noise and lighting variation.   g. The system has to be user independent and work with different people of varying facial features, such as different skin colors, shapes, and sizes.       

   The video input images  202  are passed on and processed by the FET system  203 , which efficiently handles the requirements mentioned above. The FET system  203  detects and tracks the face and facial feature images, and finally the FET system  203  superimposes  204  the face images with the selected and preprocessed virtual objects  300 . The virtual objects are selected by the user in real-time through the touch-free user interaction  115  interface. 
     FIG. 4  shows the details of the virtual stage simulation module. Customized virtual background images  400  are created and prepared offline. The music is also stored in the music box  402 . They are loaded at the beginning of the execution and can be selected using the touch-free user interaction  115  process. When a new background and a new song are selected  207 ,  401 , they are combined to simulate the virtual stage  208 . During or after the selection process, if the user moves  405 , the background also changes dynamically  403 . This dynamically changing background also contributes to the simulation of the virtual stage  208 . 
     FIG. 5  shows the virtual stage simulation by composing  505  multiple augmented images. In the exemplary embodiment shown in  FIG. 5 , the final virtual audio-visual entertainment environment  209  may be composed of multiple images, such as the original background image  500 , the image for virtual objects  502  such as musical instruments, the user&#39;s image  501  with enhanced facial images  205 , and the augmented virtual background image  503 . The touch-free interaction  115  process allows the user to select the appropriate virtual objects, such as a hat image  107  or sunglasses image  108 , to superimpose onto the user&#39;s facial image. It also allows the user to select music and the augmented virtual background image  503 , which is augmented by environmental objects, such as virtual platform images  112  and spotlight images  109  in the exemplary embodiment. The images for virtual objects  502  like musical instruments, such as a virtual guitar image  111 , may also be added to the final virtual background image in the exemplary embodiment. 
     FIG. 6  shows the dynamic background construction method in the virtual stage simulation module. When the user moves, the images change from one frame to the next. Using the differences  603  between frames, when the image-capturing device is fixed, the foreground and background image  606  can come out by the background subtraction process  600 . In the exemplary embodiment shown in  FIG. 6 , any standard background subtraction algorithm can be used. With the image-capturing device fixed, the background can be calculated by any standard model, such as the mean of the pixels from the sequence of images. The foreground  607  from this model could be defined as follows, in the exemplary embodiment shown in  FIG. 6 ;
   F   t ( x,y )=| I   i ( x,y )− B   t ( x,y )|&gt; T    
where F t  (x, y) is the foreground determination function at time t, I t  (x, y) is the target pixel at time t, B t (x, y) is the background model, and T is the threshold. The background model B t (x, y) could be represented by the mean and covariance by the Gaussian of the distribution of pixels, or the mixture of Gaussian, or any other standard background model generation method. In a paper by C. Stauffer and W. E. L Grimson, Adaptive Background Mixture Models for Real-Time Tracking, In Computer Vision and Pattern Recognition, volume 2, pages 246–253, June 1999, the authors describe a method for modeling background in more detail. The area where the user moved becomes the foreground  607  in the image.
 
   When this foreground and background image  606  is applied to the initial virtual stage image, the augmented virtual background image  503 , the foreground  607  region in the virtual stage image can be set to be transparent  601 . After the foreground  607  region is set to be transparent the boundary between the foreground and background is smoothed  602 . This smoothing process  602  allows the user to be fully immersed into the masked virtual stage image  608 . This masked virtual stage image  608  is overlapped with the user&#39;s image  501  and additional virtual object images  502 . Here the masked virtual stage image  608  is positioned in front of the user&#39;s image  501 , and the user&#39;s body image is shown through the transparency channel region of the masked virtual stage image  608 . 
   When the user does not move, the virtual stage image could hide the user&#39;s body image since the foreground and background image  606  from the background subtraction might not produce clear foreground and background images  606 . This is an interesting feature for the invention because it can be used as a method to ask the user to participate in the movement or dance as long as the user wants to see themselves. This interesting feature could be also disabled so that the user&#39;s body is always shown through the masked virtual stage image  608 . It is because the previous result of the background subtraction is still correct and can be used when there is no user&#39;s motion unless the user is totally out of the interaction. When the user is totally out of the interaction, the face detection process, in the facial image enhancement module  200 , recognizes this and terminates the execution of the system. This dynamic background construction process is repeated as long as the user moves in front of the image-capturing device. The masked virtual stage image  608  changes dynamically according to the user&#39;s arbitrary motion in real-time within this loop. The virtual objects, such as the virtual guitar image  111 , also moves along with the user&#39;s motion in real-time. This whole process makes the final virtual audio-visual entertainment environment  209  on the screen enhance the stage environment and enables the user to experience a new and active experience.