Abstract:
A projection system that prevents projection light on a presenter and provides a gesture based interface for visual enhancements is disclosed. The system may include a projector camera system comprising a computer communicating an image to a projector, the projector projecting the image on a screen, a stereo camera unit mounted approximately in the plane of the screen or at the projector and directed toward the presenter and communicating with the computer, and software that interprets the stereo camera data to distinguish and manipulate foreground and background features. The foreground feature may be the presenter relative to the screen or to the audience and room, or the presenter&#39;s hand relative to the presenter. The invention employs imaging stereo camera algorithms and techniques developed for foreground/background segmentation, image manipulation, and gesture recognition.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a projection presentation system, and more particularly, to a projection presentation system which allows a presenter to perform a presentation with minimized projection on the speaker when he is in front of the screen. 
     2. Introduction 
     In a presentation where a presenter shows an audience presentation materials by displaying the materials on a monitor screen or projecting screen, the presenter explains the material by gesturing at the presentation materials being displayed using his hands or a pointer bar or laser pointer or the like. Whether using a rear-projection system or a front projector system, the presenter interacts with a computer by directly operating the computer in order to display or operate an object like a video or file contained in the presentation materials. Generally, presentations are problematic in that there is a restriction on the interaction the presenter can perform and the procedure or interaction is not natural as compared to a presentation without a computer. An additional problem with front projection systems is that part of the projection can land on the presenter, causing discomfort and disorientation. Being in the projection beam, the presenter is blinded by the projector and cannot see the audience. From the observer&#39;s point of view, text and graphics projected onto the speaker are quite distracting to an audience. Rear-projection systems, while not suffering the projection on the presenter problem, are expensive and require specialized projection surfaces and space behind the screen for projectors. 
     For the reasons stated above, and for other reasons stated below which would become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for controlling the projecting beam impinging on the presenter. Further, there is a need in the art for a presentation system by which a presenter can interact with the presentation material in real time using gesture commands and manipulate the entire presentation from a natural position standing near a screen. 
     SUMMARY OF THE INVENTION 
     A projection system that prevents projection light on a presenter and provides a gesture based interface for visual enhancements is disclosed. The system may include a projector camera system comprising a computer communicating an image to a projector, the projector projecting the image on a screen, a stereo camera unit mounted approximately in the plane of the screen or at the projector and directed toward the presenter and communicating with the computer, and software that interprets the stereo camera data to distinguish and manipulate foreground and background features. The foreground feature may be the presenter relative to the screen or to the audience and room, or the presenter&#39;s hand relative to the presenter. The invention employs imaging stereo camera algorithms and techniques known in the art for foreground/background segmentation, image manipulation, and gesture recognition. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to describe the manner in which the above-recited and other advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1  illustrates an exemplary diagram of a projector system employing stereo cameras for detecting a speaker&#39;s position and gestures in accordance with a possible embodiment of the invention; 
         FIG. 2  illustrates an exemplary diagram of a projector system employing stereo cameras mounted at the viewing surface for detecting a speaker&#39;s position and gestures in accordance with a possible embodiment of the invention; 
         FIG. 3  illustrates an image of an object/speaker isolated from the background in accordance with a possible embodiment of the invention; 
         FIG. 4  illustrates an image of a speaker&#39;s gesture isolated from the background in accordance with a possible embodiment of the invention; 
         FIG. 5  shows a front projection image being displayed on a presenter and how such an image can affect the overall presentation; 
         FIG. 6  illustrates a dynamic mask image created by isolating the presenter from the background in accordance with a possible embodiment of the invention; 
         FIG. 7  illustrates a dynamic mask image merged into an image being displayed on a viewing surface in accordance with an embodiment of the invention; 
         FIG. 8  is an illustration of the manipulation of a presentation through gestures in accordance with an embodiment; 
         FIG. 9  is an exemplary flowchart illustrating one possible process in accordance with one possible embodiment of the invention; 
         FIG. 10  is an exemplary flowchart illustrating one possible gesturing command identification process in accordance with one possible embodiment of the invention; and 
         FIG. 11  is an exemplary flowchart illustrating one possible position identification process in accordance with one possible embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Additional features and 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. The features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth herein. 
     Various embodiments of the invention are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the invention. 
     The invention comprises a variety of embodiments, such as a method and apparatus and other embodiments that relate to the basic concepts of the invention. 
     The term “gesture” as used herein includes positions or shapes made using one or more hands or other body parts or other devices and also motions or motion patterns made using one or more hands, static symbols, or other body parts or other devices. These gestures may be correlated to various actions, as described in more detail below. 
     The term “projection screen”, “viewing surface”, or “screen” as used herein includes white, beaded, metallic, or metallic coated lenticular surfaces, or any surface suitable for viewing a projected image. 
     This invention concerns a projection system that eliminates projections on a speaker. As a corollary benefit this invention can also provide a gesture based interface for controlling a projected image. 
       FIG. 1  illustrates an exemplary diagram of a projection system  100  in accordance with a possible embodiment of the invention. In particular, the projection system includes a first camera  120 , a second camera  125 , and a projection device  180  that includes a processor  140 , a storage device  150 , an input/output device  160 , a data bus  170 , a driver  130 , and a projected image  110 . Data bus  170  may permit communication among the components of the projection device  180  and cameras ( 120 , 125 ). Processor  140  may include at least one conventional processor or microprocessor that interprets and executes instructions. Memory or storage  150  may be a read only memory (ROM, a random access memory (RAM, or another type of dynamic storage device that stores information and instructions for execution by processor  140 . Storage  150  may also store temporary variables or other intermediate information used during execution of instructions by processor  140 . ROM may include a conventional ROM device or another type of static storage device that stores static information and instructions for processor  140 . Storage device  150  may include any type of media, such as, for example, magnetic or optical recording media and its corresponding drive. 
     Input/output device  160  may include one or more conventional mechanisms that permit a user to input information to projection device  180 , such as a keyboard, a mouse, a pen, a voice recognition device, etcetera. An output device may include one or more conventional mechanisms that output information to the user, including a display, a printer, one or more speakers, or a medium, such as a memory or a magnetic or optical disk and a corresponding disk drive. An input/output device  160  may also be a communication interface that includes any transceiver-like mechanism that enables the projection system  100  to communicate via a network such as a modem or an Ethernet interface for communicating via a local area network (LAN). 
     First camera  120  and second camera  125  are for capturing a left and right image for developing a stereoscopic view of the scene. If the fields of view of each camera overlap at least in part, one or more objects of the scene can be seen in both images. The first camera  120  and second camera  125  are a stereo camera or system comprising two or more monocular cameras for tracking the motion of the presenter  170 . The presenter  170  is able to remotely interact with the projection device  180  by gesturing commands with part of his body. 
     When the first camera  120  and the second camera  125  are oriented towards the viewing surface or presentation screen  115  as shown, the speaker or presenter  170  is in the foreground relative to the screen  115 . The stereo camera system consisting of first camera  120  and second camera  125  captures images of a foreground object (image of presenter  170 ) and a background object (image of presentation screen  115 ) and outputs these images to processor  140  so as to perform a depth imaging analysis. The depth imaging analysis separates the foreground image from the background image and determines the position of one or more foreground objects such as presenter  170 , or the presenter&#39;s hand or arm, and uses this determination to modify a projected at least one image based on the position of the foreground object. A suitable modification in the projection environment is limiting the projected image to only the viewing surface, or limiting the projection on the presenter by reducing the intensity of the projected light or by shining a non-image light that illuminates the presenter at a brightness level that is comfortable for both the presenter and the audience. In another embodiment, a suitable modification in the projection environment is limiting the projected image to only the foreground object. This embodiment enables novel presentation schemes, such as the projection of text and graphics on the presenter&#39;s shirt or body, or on one or more static or mobile foreground objects, including objects held by the presenter. The projection may also be modified so different image contents are projected on the viewing surface and on the presenter&#39;s shirt or body or on one or more static or mobile foreground objects, including objects held by the presenter. The depth imaging analysis is also able to segment the scene into more than two foreground/background segments, for example to isolate a foreground object from background and further to isolate one or more parts of the foreground object from the foreground object. In the preferred embodiment, the isolated part of the foreground object is a gesturing hand that can be used to invoke enhanced presentation features such as highlighting text, highlighting objects, invoking a magnifying glass visual effect, selecting a slide from a slide show, controlling the projection device, and other visual enhancements or presentation aids. 
     It will be understood by those of ordinary skill in the art that the internal parameters of the cameras and projector and the external geometric relationships of the cameras, the projector, or the objects in the scene relative to each other can optionally be used to improve the quality, accuracy, or both of the modification of the projection. 
     It will also be understood by those of ordinary skill in the art that the embodiments described in this disclosure can also be enabled by visual or non-visual means of acquiring a depth image other than a stereo camera or two monocular cameras. Examples of alternative means of acquiring depth images include, but are not limited to, laser, sonar, and infrared range finders, and the use of projected structured light patterns. The exemplary embodiments will be described in terms of stereo cameras or two monocular cameras only, in order to avoid obscuring the pedagogical value of the description of the embodiments. 
     Projector driver  130  may change the projected image  110  in response to information received from processor  140 . For example, processor  140  may cause projector driver  130  to modify the image in response to the current position, motion, and orientation of projector device  180 . Most importantly, processor  140  may cause projector driver  130  to modify the projected image  110  based on the position of the presenter  170  and on the commands initiated by presenter  170 . Projector driver  130  may be any type of suitable projector. In some embodiments, projector driver  130  is a small, light, battery-operated projector. 
       FIG. 2  is an illustration of an alternative projection system  200  in accordance with a possible embodiment of the invention. In particular, projection system  200  comprises a projection device  180 , an optional workstation  210 , a screen  115 , a stereo camera  220  or system comprising two or more monocular cameras positioned at presentation screen  115 . The stereo camera  220  captures images of a foreground object (image of presenter  170 ) and a background object (image of presentation device  180  or the audience or elements of the presentation room) and outputs them to processor  140  so as to perform a depth imaging analysis. In this arrangement, the processing could be performed by computer  210 . The depth imaging analysis separates the foreground image from the background image and determines the position of a foreground object such as the presenter  170  to modify a projected at least one image based on the position of the foreground object. A suitable modification in the projection environment is limiting the projected image to only the viewing surface, or limiting the projection on the presenter by reducing the intensity of the projected light or by shining a non-image light that illuminates the presenter at a brightness level that is comfortable for both the presenter and the audience. In another embodiment, a suitable modification in the projection environment is limiting the projected image to only the foreground object. The projection may also be modified so different image contents are projected on the viewing surface and on the presenter&#39;s shirt or body or on one or more static or mobile foreground objects, including objects held by the presenter. The depth imaging analysis is also able to segment the scene into more than two foreground/background segments, for example to isolate a foreground object from background and further to isolate one or more parts of the foreground object from the foreground object. In the preferred embodiment, the isolated part of the foreground object is a gesturing hand that can be used to invoke enhanced presentation features such as highlighting text, highlighting objects, invoking a magnifying glass visual effect, selecting a slide from a slide show, controlling the projection device, and other visual enhancements or presentation aids. 
       FIG. 3  is an illustration of an isolated foreground object in accordance with an embodiment. The isolation is accomplished through a depth imaging process using inexpensive stereo image sensors. The stereo depth imaging analysis produces a depth image whose pixel values represent the distance of the object to the camera  220 , or first camera  120  and second camera  125  at that pixel. A stereo depth image can provide the scene&#39;s 3-D shape information regardless of texture variations such as clothing and shadow variations. Here the presenter  170  or foreground speaker  310  is isolated from the background  320 . 
       FIG. 4  is an illustration of an isolated gesture in accordance with an embodiment of the invention. Here the presenter&#39;s gesture  410  is isolated to produce an image of the gesture. The gesture can then be used to command, control, or invoke an enhanced feature of the projection system. The gesture can be one of a variety of hand gestures of a user that are recognized by software running in processor  140 . From the gesture, processor  140  generates a command to perform an action such as highlighting text, highlighting objects, invoking a magnifying glass visual effect, selecting a slide from a slide show, controlling the projection device, or other visual enhancements or presentation aids. 
     For example, an outstretched hand tracking in a certain direction could indicate moving a window in that direction, a finger pointing in a particular direction could indicate invoking a magnifying glass, while moving towards or away from the screen could indicate more or less magnification, respectively. Further, pointing at a text or graphic object could highlight that object. The processor  140  may be configured to recognize various tracking patterns, such as various hand-related gestures such as a hand or finger moving from right to left, bottom to top, in and out, etcetera. Alternatively, processor  140  could be trained with an image recognition program to correlate various images or motion patterns to various control actions. In a possible implementation, image gestures received through first camera  120  and second camera  125  or stereo camera  220  are compared to at least one of a set of gestures stored in a suitable storage device, or correspond to a pre-defined motion pattern recognized by an image recognition program in processor  140 . The processor may then forward information identifying the gesture to other devices or applications to invoke an action. 
       FIG. 5  is an illustration of a presenter  170  occluding the presentation and being projected upon by the projection device. As shown, the projected light or projected image  510  is blocked by the presenter  170 . Stated differently, the projected image falls upon the presenter when the presenter enters into the projected image. This is undesirable for both presenter and audience: the presenter may be blinded by the bright projected light, while the audience is denied a clear view of the presenter and is distracted by the image and text projected onto the presenter&#39;s face and body. For these reasons it is desirable to separate the presenter  170  from the image being projected upon him. 
       FIG. 6 . is an illustration of a dynamic mask corresponding to an isolated image of a presenter in accordance with a possible embodiment. The mask is derived from a depth imaging segmentation of foreground and background. Depth imaging provides a practical method of identifying those pixels of a projected image that are occupied by the presenter or other foreground object being projected onto by the projection device. If the viewpoint of the depth image is the same (or very close) to that of the projector, the isolated image can be computed by directly identifying the foreground pixels in the depth image. If the viewpoint of the depth image is not close enough to that of the projector, the foreground pixel positions from the depth image need to be mapped to the viewpoint of the projector. Given the known relative  3 D position of the projector viewpoint with respect to the viewpoint of the depth image, and the depth information of the foreground pixels, this mapping can be done using a simple projective transformation, as is known to those of ordinary skill in the art. The identified pixels are converted to a silhouette or a dynamic mask  610  of the presenter or other foreground object. The mask  610  is dynamic in that its shape and size are modified in real time according to the presenter&#39;s movement and position. The dynamic mask  610  can then be combined with the projected image to inhibit or reduce or otherwise modify the projected image in that area occupied by the presenter. Put another way, the created dynamic mask is used so that at least one pixel of a projected image is modified according to its location with respect to the dynamic mask. 
       FIG. 7  is a modification of a projected image with a dynamic mask in accordance to an embodiment of the invention. The dynamic mask  610  has been combined with the projected image to produce a composite image. This composite image when projected by projection device  180  will have the illumination modified  710  for the pixels corresponding to the presenter&#39;s position. The modification is a reduction in illumination, a substitution of colors or textures that blend better with the presenter, shining a non-image light on the presenter, or other effect designed to improve the presenter&#39;s or the audience&#39;s presentation experience. 
       FIG. 8  is a presenter invoking enhanced features of a projection system  800  in accordance with an embodiment of the invention. In addition to inhibiting the illumination on the presenter  170 , it would be advantageous to have the presenter be able to manipulate the entire presentation from a natural position standing near a screen. Here the presenter has a presentation  830  that has enhanced features like a magnifying glass visual effect  820 . Other enhanced features are possible such as highlighting text, highlighting objects, selecting a slide from a slide show, controlling the projection device, or other visual enhancements or presentation aids. As noted above, the gestures of the presenter  170  can be isolated and a command can be identified from the acquired depth image. 
       FIG. 9  is an exemplary flowchart illustrating some of the basic steps associated with a projection process  900  in accordance with a possible embodiment of the invention. The process begins at step  910  by projecting at least one image onto a viewing surface and continues to step  920  where a depth image is acquired. The depth image can be acquired by employing a vision based input device such as a stereo camera or a system comprising two or more monocular cameras and stereoscopic depth processing. These cameras can be positioned at the projection device or at the viewing surface. 
     At step  930 , through depth imaging analysis the position of the foreground object can be determined. Alternatively or in parallel the gesture of the presenter can be determined in step  940  to identify a command. 
     At step  950 , the projection is controlled by modifying the projected at least one image based on the position of the foreground object. Alternatively or in addition, the projected at least one image is modified by performing the identified command (step  940 ) such as highlighting text, highlighting objects, invoking a magnifying glass visual effect, selecting a slide from a slide show, controlling the projection device, or other visual enhancements or presentation aids. 
     The process goes to step  960  and is repeated. 
       FIG. 10  is an exemplary flowchart illustrating some of the basic steps associated with a command gesturing process  1000  in accordance with a possible embodiment of the invention. The process begins at step  1010  with receiving a gesture from the presenter. The gesture is an isolation of the presenter&#39;s hand, arm, or other body part as described in  FIG. 4 . Once the gesture has been received, control passes to step  1020  for further processing. In step  1020 , the gesture is identified by comparison to at least one stored gesture using pattern recognition means, or other gesture identification means. The gesture, such as one of various hand gestures of a user, is recognized by software running in processor  140 . In step  1030 , the identified gesture is processed to determine a command. Processor  140  generates a command to perform an action such as highlighting text, highlighting objects, invoking a magnifying glass visual effect, selecting a slide from a slide show, controlling the projection device, or other visual enhancements or presentation aids. In step  1040 , the commanded action is performed by the projection system  100 . 
       FIG. 11  is an exemplary flowchart illustrating some of the basic steps associated with an application of a dynamic mask projection process  1100  in accordance with a possible embodiment of the invention. In step  1110 , a depth image is received. In step  1120 , the depth image is processed to identify those pixels of a projected image that are occupied by the presenter or other foreground object being projected onto by the projection device. In step  1130 , a dynamic mask is created from the pixels identified in step  1120 . In step  1140 , the dynamic mask is combined with the projected image. In a variation of step  1140 , alternative image contents may be combined with the projected image within the dynamic mask region, outside the dynamic mask region, or both within and outside the dynamic mask region. 
     The projection system may perform such functions in response to processor  140  by executing sequences of instructions contained in a computer-readable medium, such as, for example, storage  150 , a magnetic disk, or an optical disk. Such instructions may be read into storage  150  from another computer-readable medium or from a separate device via input/output device  160  communication interface. 
     The hardware illustrated in  FIG. 1  and the related discussion are intended to provide a brief, general description of a suitable computing environment in which the invention may be implemented. Although not required, the invention will be described, at least in part, in the general context of computer-executable instructions, such as program modules being executed by a computer, such as a general purpose computer. Generally, program modules include routine programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Moreover, those skilled in the art will appreciate that other embodiments of the invention may be practiced in network computing environments with many types of computer system configurations, including personal computers, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like. 
     Embodiments may also be practiced in distributed computing environments where tasks are performed by local and remote processing devices that are linked (either by hardwired links, wireless links, or by a combination thereof) through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices. 
     Embodiments within the scope of the present invention may also include computer-readable media for carrying or having computer-executable instructions or data structures stored thereon. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions or data structures. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or combination thereof) to a computer, the computer properly views the connection as a computer-readable medium. Thus, any such connection is properly termed a computer-readable medium. Combinations of the above should also be included within the scope of the computer-readable media. 
     Computer-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Computer-executable instructions also include program modules that are executed by computers in stand-alone or network environments. Generally, program modules include routines, programs, objects, components, and data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of the program code means for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps. 
     Although the above description may contain specific details, they should not be construed as limiting the claims in any way. Other configurations of the described embodiments of the invention are part of the scope of this invention. For example, the principles of the invention may be applied to each individual user where each user may individually deploy such a system. This enables each user to utilize the benefits of the invention even if any one of the large number of possible applications do not need the functionality described herein. In other words, there may be multiple instances of the projection system in  FIGS. 1-2 , each processing the content in various possible ways. It does not necessarily need to be one system used by all end users. Accordingly, only the appended claims and their legal equivalents should define the invention, rather than any specific examples given.