Patent Publication Number: US-2018046254-A1

Title: Information display device and information display method

Description:
TECHNICAL FIELD 
     The present invention relates to an information display device and an information display method in which a command from an operator (user) is inputted by a gesture made by the operator. 
     BACKGROUND ART 
     Gesture UIs (User Interfaces) are beginning to be employed in recent years as user interfaces of television sets (broadcast receivers), PCs (Personal Computers), car navigation systems, digital signage systems and so forth. The gesture UI enables an operator to operate a device by gesture, such as body motion or body shape of the operator (e.g., hand motion, hand shape, finger motion, finger shape, etc.). For example, with a gesture UI employing the hand pointing and moving a pointer on the screen of a display unit (display) according to a hand motion, when the operator makes a gesture of pointing at a pointer position with a hand, the pointer on the screen is moved according to the gesture. 
     The gesture UI detects (captures images of) the operator&#39;s gesture by using a gesture detection unit (sensor unit) such as an image capturing device like an RGB (Red, Green, Blue) camera or a ToF (Time of Flight) sensor. The gesture UI identifies (determines) the gesture by analyzing image data obtained by capturing images of the operator and outputs a signal representing command content meant by the gesture. However, as the operator gets farther from the gesture detection unit (sensor unit), the size of the operator in the image of each frame generated by the image capturing decreases and the moving amount of a body part by the operator&#39;s gesture also decreases. As above, when the operator is situated at a position far from the gesture detection unit, the gesture UI has to identify (determine) the gesture based on the small movement of the body part and output the signal representing the command content indicated by the gesture. Therefore, a problem occurs with the gesture UI in that the gesture is erroneously identified (determined) or the gesture cannot be identified when the operator is far from the gesture detection unit. 
     Patent Reference 1 proposes an image processing device that sets an operation target region based on the position and the size of a detection object in an image generated by an image capturing device as the gesture detection unit. In the image processing device, by setting the operator&#39;s hand or face as the detection object, the ratio between the size of the operation target region that is set and the size of the operator&#39;s hand or face included in the operation target region is maintained constant. Accordingly, the operability for the operator improves. 
     PRIOR ART REFERENCE 
     Patent Reference 
     
         
         Patent Reference 1: Japanese Patent Application Publication No. 2013-257762 
       
    
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     However, even with each conventional technology described above, as the operator gets farther from the gesture detection unit, the size of the operator in the image of each frame generated by the image capturing decreases, and thus there is a problem in that erroneous gesture identification by the gesture UI becomes likely to occur. 
     It is therefore an object of the present invention, which has been made to resolve the above-described problem with the conventional technologies, to provide an information display device and an information display method with which the erroneous identification of the operator&#39;s gesture is unlikely to occur even when the operator is situated at a position far from the information display device. 
     Means for Solving the Problem 
     An information display device according to the present invention includes a display control unit that makes a display unit display information, a gesture detection unit that generates gesture information based on a gesture made by an operator, a gesture identification unit that makes identification of the gesture based on the gesture information generated by the gesture detection unit and outputs a signal based on a result of the identification, a distance estimation unit that estimates distance between the operator and the display unit, and an identification function setting unit that stores a first set distance previously determined and sets gestures identifiable by the gesture identification unit so that the number of gestures identifiable by the gesture identification unit when the distance is over the first set distance is smaller than the number of gestures identifiable by the gesture identification unit when the distance is less than or equal to the first set distance. 
     An information display method according to the present invention is an information display method executed by an information display device that makes a display unit display information, including a gesture detection step of generating gesture information based on a gesture made by an operator, a gesture identification step of making identification of the gesture based on the gesture information generated in the gesture detection step and generating a signal based on a result of the identification, a distance estimation step of estimating distance between the operator and the display unit, and an identification function setting step of setting gestures identifiable in the gesture identification step so that the number of gestures identifiable in the gesture identification step when the distance is over a first set distance predetermined is smaller than the number of gestures identifiable in the gesture identification step when the distance is less than or equal to the first set distance. 
     Effects of the Invention 
     In the present invention, the identifiable gestures are set so that the number of the identifiable gestures decreases when the operator is situated at a position far from the display unit of the information display device. As above, by the present invention, when the operator is situated at a position far from the display unit, an erroneous identification of the operator&#39;s gesture can be made unlikely to occur by excluding gestures with a small body movement from the identifiable gestures, for example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram showing usage status of an information display device according to a first embodiment of the present invention. 
         FIG. 2  is a block diagram schematically showing the configuration of the information display device according to the first embodiment. 
         FIG. 3  is a diagram showing an example of an image acquired by the information display device according to the first embodiment by capturing an image of an operator. 
         FIG. 4  is a schematic diagram showing operational states of the info/notion display device according to the first embodiment. 
         FIG. 5  is a diagram showing an example of an image displayed on a display unit of the information display device according to the first embodiment. 
         FIG. 6  is a diagram showing another example of the image displayed on the display unit of the information display device according to the first embodiment. 
         FIG. 7  is a diagram showing another example of the image displayed on the display unit of the information display device according to the first embodiment. 
         FIG. 8  is a diagram showing another example of the image displayed on the display unit of the information display device according to the first embodiment. 
         FIG. 9  is a diagram showing another example of the image displayed on the display unit of the information display device according to the first embodiment. 
         FIGS. 10( a ) and 10( b )  are diagrams showing transition of the image displayed on the display unit of the information display device according to the first embodiment (in a case where the operator is situated at a position close to the display unit). 
         FIGS. 11( a ) and 11( b )  are diagrams showing transition of the image displayed on the display unit of the information display device according to the first embodiment (in a case where the operator is situated at a position far from the display unit). 
         FIGS. 12( a ) to 12( c )  are schematic diagrams showing usage status of the information display device according to the first embodiment. 
         FIG. 13  is a flowchart showing an initial setting of the information display device according to the first embodiment. 
         FIG. 14  is a flowchart showing the operation of the information display device according to the first embodiment. 
         FIG. 15  is a flowchart showing the operation of an information display device according to a second embodiment of the present invention. 
         FIG. 16  is a schematic diagram showing usage status of an information display device according to a third embodiment of the present invention. 
         FIG. 17  is a block diagram schematically showing the configuration of the information display device according to the third embodiment. 
         FIG. 18  is a schematic diagram showing usage status of an information display device according to a fourth embodiment of the present invention. 
         FIG. 19  is a block diagram schematically showing the configuration of the information display device according to the fourth embodiment. 
         FIG. 20  is a block diagram schematically showing the configuration of an information display device according to a fifth embodiment of the present invention. 
         FIG. 21  is a block diagram schematically showing the configuration of an information display device according to a modification of the fifth embodiment. 
         FIG. 22  is a flowchart showing the operation of the information display device according to the fifth embodiment. 
         FIG. 23  is a block diagram schematically showing the configuration of an information display device according to a sixth embodiment of the present invention. 
         FIG. 24  is a flowchart showing the operation of the information display device according to the sixth embodiment. 
         FIG. 25  is a schematic diagram showing usage status of an information display device according to a seventh embodiment of the present invention. 
         FIG. 26  is a block diagram schematically showing the configuration of the information display device according to the seventh embodiment. 
         FIG. 27  is a flowchart showing the operation of the information display device according to the seventh embodiment. 
         FIG. 28  is a hardware configuration diagram showing the configuration of a modification of the information display devices according to the first to seventh embodiments. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     &lt;1&gt; First Embodiment 
     &lt;1-1&gt; Configuration 
       FIG. 1  is a schematic diagram showing usage status of an information display device  1  according to a first embodiment of the present invention. As shown in  FIG. 1 , the information display device  1  includes a display unit  30  as a display and a gesture detection unit (sensor unit)  10  as an image capturing unit such as an image capturing device (camera) or a ToF. The information display device  1  includes a gesture UI that operates the information display device  1  according to a gesture made by an operator (user)  2 . In the first embodiment, the gesture detection unit  10  is attached to a top part of a main body of the information display device  1 . However, the gesture detection unit  10  may be stored in the main body of the information display device  1  or provided in the vicinity of the main body of the information display device  1 . In cases where the information display device  1  holds information indicating the positional relationship between the gesture detection unit  10  and the main body of the information display device  1 , the gesture detection unit  10  may be provided at a position apart from the main body of the information display device  1 . The operator  2  inputs command information to the information display device  1  by a gesture as a motion and shape of the operator  2 &#39;s body (e.g., predetermined motion and pose of a hand  2 A and a finger  2 B, expression of the face  2 C, or the like). For example, the operator  2 &#39;s motion of moving the hand  2 A to right direction, motion of moving the hand  2 A to left direction, motion of moving the hand  2 A to the upward direction, motion of moving the hand  2 A to the downward direction, motion of pointing with the finger  2 B, motion of forming a peace sign with the hand  2 A and fingers  2 B, etc. can be taken as examples of the gesture. 
       FIG. 2  is a block diagram schematically showing the configuration of the information display device  1  according to the first embodiment. The information display device  1  is a device capable of executing an information display method according to the first embodiment. As shown in  FIG. 2 , the information display device  1  includes the gesture detection unit  10  as the image capturing unit and a control unit  20 . The information display device  1  may further include the display unit  30  as the display and a storage unit  40  such as a memory. The control unit  20  includes a distance estimation unit  21 , an identification function setting unit  22 , a gesture identification unit (gesture judgment unit)  23 , and a display control unit  25 . The information display device  1  may further include a function execution unit  24 . 
     The gesture detection unit  10  generates gesture information G 1  based on a gesture GE performed by the operator  2 . For example, the gesture detection unit  10  captures images of the operator  2 &#39;s gesture GE and generates the gesture information G 1  including image data corresponding to the gesture GE. The image data is, for example, still image data of a plurality of frames arranged in the order of time or video image data. Incidentally, while a case where the gesture detection unit  10  is an image capturing unit is described in the first embodiment, the gesture detection unit  10  may be a different type of device such as an operating device (described in a fourth embodiment) attached to a part of the operator  2 &#39;s body as long as the device is capable of generating gesture information corresponding to the operator  2 &#39;s gesture. 
     The gesture identification unit  23  makes the identification (determination) of the gesture based on the gesture information G 1  generated by the gesture detection unit  10  and outputs a signal G 2  based on the result of the identification. Here, the identification of the gesture means a process of identifying or determining what kind of command content is indicated by the gesture made by the operator  2 . 
     The gesture identification unit  23  detects a motion pattern of the gesture from the image data generated by the gesture detection unit  10 . In this case, the gesture identification unit  23  detects the motion pattern of the gesture by analyzing displacement of a detection region including a part of the operator  2 &#39;s body based on still image data of a plurality of frames arranged in the order of time or video image data. 
     In cases where the gesture detection unit  10  is a stereo camera capable of acquiring information on the depth of the subject, the gesture identification unit  23  detects the motion pattern of the gesture by estimating the three-dimensional position of the detection region including a part of the operator  2 &#39;s body. 
     In cases where the gesture detection unit  10  is a monocular camera having one lens, the gesture identification unit  23  detects the motion pattern of the gesture based on a distance D 0  estimated by the distance estimation unit  21  and the image data of the detection region. 
     The storage unit  40  stores a gesture database (DB)  40   a  in which each of a plurality of reference gestures is associated with command content corresponding to the plurality of reference gesture. The gesture identification unit  23  compares the detected motion pattern with each of the plurality of reference gestures stored as the gesture DB  40   a  and determines a reference gesture corresponding to the detected motion pattern from the stored the plurality of reference gestures. The gesture identification unit  23  judges that the command content associated with the determined reference gesture is the command content by the operator  2 . Incidentally, the gestures and the command contents stored in the storage unit  40  as the gesture DB  40   a  have been stored in the storage unit  40  previously. It is also possible to allow the operator  2  to determine the gestures and the command contents corresponding to the gestures and store the determined gestures and command contents in the storage unit  40  as the gesture DB  40   a.    
     The distance estimation unit  21  estimates the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) based on the gesture information G 1  outputted from the gesture detection unit  10 , and supplies distance information G 3  representing the distance D 0  to the identification function setting unit  22  and the display control unit  25 . As shown in  FIG. 1 , in the first embodiment, the distance between the operator  2  and the display unit  30  equals the distance between the operator  2  and the gesture detection unit  10 , or has a certain relationship with the distance between the operator  2  and the gesture detection unit  10 , and is calculable. For example, the distance estimation unit  21  detects a particular part of the operator  2 &#39;s body included in the image data as the detection region and estimates (calculates) the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) based on the size of the detection region in the image of each frame. Incidentally, the distance estimation unit  21  may calculate the distance D 0  by a different method. 
       FIG. 3  is a diagram showing an example of an image  200  acquired by the gesture detection unit  10  of the information display device  1  according to the first embodiment by capturing an image of the operator  2 . The distance estimation unit  21  detects the hand  2 A of the operator  2  included in the image  200  as a detection region  201 . Here, the distance estimation unit  21  detects the operator&#39;s skin color from information on colors included in the image and specifies a particular part of the operator  2 &#39;s body as the detection region. In cases where the detection region is the face, it is also possible to judge the region of the entire face after judging parts (eyes, nose, mouth, etc.) of the face. The distance estimation unit  21  may employ a different method, such as judging the face by a method of setting a search window in the image and judging whether each region is a face region or not by use of a classifier. For example, it is possible to set both the face and the hand  2 A of the operator  2  as the detection regions. The distance estimation unit  21  estimates (calculates) the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) based on the size of the detection region  201  in the image  200 . 
     In the estimation of the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) by the distance estimation unit  21 , there are cases where the distance D 0  is estimated and cases where it is judged whether the operator  2  is situated at a position closer to the display unit  30  than a predetermined reference distance or at a position farther from the display unit  30  than the predetermined reference distance. 
     In cases where the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) is estimated (calculated), the distance estimation unit  21  previously stores correlation data between the size of the detection region  201  in the image  200  and the distance D 0 . The distance estimation unit  21  estimates (calculates) the distance D 0  based on the correlation data and the size of the detection region  201  in the generated image  200 . The size of the detection region  201  can be derived from the area of the detection region  201  or at least one of the vertical length Lv and the horizontal length Lh of the detection region  201 . 
     In cases of judging whether the operator  2  is situated at a position closer to the display unit  30  than the predetermined reference distance or at a position farther from the display unit  30  than the predetermined reference distance, the distance estimation unit  21  previously stores a reference position, as a position where the operator  2  is supposed to perform a gesture, and the size of the detection region  201  at the reference position in the image  200  as the correlation data. The distance estimation unit  21  judges whether the operator  2  is situated at a position closer than the reference position or at a position farther than the reference position based on the correlation data and the size of the detection region  201  in the generated image  200 . In this case, the number of calculations by the control unit  20  is reduced. 
     The identification function setting unit  22  stores a predetermined first set distance D 1 , and sets gestures identifiable by the gesture identification unit  23  so that the number of gestures identifiable by the gesture identification unit  23  when the distance D 0  is over the first set distance D 1  is smaller than the number of gestures identifiable by the gesture identification unit  23  when the distance D 0  is less than or equal to the first set distance D 1 . The first set distance D 1  is previously set when the use of the information display device  1  is started. 
     The identification function setting unit  22  does not limit the gestures identifiable by the gesture identification unit  23  when the distance D 0  is less than or equal to the first set distance D 1 . In this case, the operational state of the information display device  1  is referred to as a full-function mode. The identification function setting unit  22  notifies the gesture identification unit  23  of the identifiable gestures and notifies the display control unit  25  of the operational state of the information display device  1 . 
     The identification function setting unit  22  limits the gestures identifiable by the gesture identification unit  23  when the distance D 0  is greater than the first set distance D 1  and less than or equal to a second set distance D 2 . Here, the limited identifiable gestures are gestures for functions of a high frequency of use by the operator  2 . In this case, the operational state of the information display device  1  is referred to as a limited function mode. 
     The identification function setting unit  22  further limits the gestures identifiable by the gesture identification unit  23  when the distance D 0  is greater than the second set distance D 2 . Here, the further limited identifiable gestures are gestures for functions of a still higher frequency of use by the operator  2 . In this case, the operational state of the information display device  1  is referred to as a specified function mode. 
     The distance D 2  used by the identification function setting unit  22  as a reference is assumed to be a distance at which the gesture recognition by the gesture identification unit  23  is difficult. This distance D 2  is set based on one or more or all of sensor performance such as the resolution of the camera used for the gesture detection unit  10 , spectral filter information, lens performance such as MTF (Modulation Transfer Function), information on illumination environment such as color and illuminance of illuminating light, and size and color information on the detection object. 
     The function execution unit  24  executes a function based on the signal G 2  outputted from the gesture identification unit  23 . Further, the function execution unit  24  notifies the display control unit  25  of the result of executing the function. 
     The display control unit  25  controls the display operation of the display unit  30 . For example, the display control unit  25  generates an operation menu and makes the display unit  30  display the operation menu. The display control unit  25  sets display layout and display content on the display unit  30  based on which of the full-function mode, the limited function mode or the specified function mode the operational state set by the identification function setting unit  22  is. Further, the display control unit  25  may adjust sizes of characters, icons and a pointer displayed on the display unit  30  based on the distance D 0  estimated (calculated) by the distance estimation unit  21 . For example, the display control unit  25  decreases the sizes of the displayed characters, icons and pointer when the distance D 0  is short and increases the sizes of the displayed characters, icons and pointer with the increase in the distance D 0 . With such adjustment, visibility of icons, characters, pointer, etc. is maintained. Furthermore, the display control unit  25  makes the display unit  30  display the result supplied from the function execution unit  24 . 
     &lt;1-2&gt; Operation 
       FIG. 4  is a schematic diagram showing the operational states of the information display device  1  according to the first embodiment.  FIG. 4  shows relationship among the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ), types of gestures identifiable (usable) by the information display device  1  when the operator  2  operates the information display device  1  by gesture, and the state of the information display device  1 . In the example of  FIG. 4 , the gestures identifiable (usable) when the operator  2  operates the information display device  1  by gesture are classified into three types of gestures GE 1 , GE 2  and GE 3 . The three types of gestures differ from each other in the easiness of the identification by the information display device  1 . For example, the first type of gesture GE 1  is a swipe as the operator  2 &#39;s motion of waving a hand, the second type of gesture GE 2  is pointing as the operator  2 &#39;s motion of pointing a direction or position with a finger, and the third type of gesture GE 3  is the operator  2 &#39;s pose of making a particular shape with a hand. The first type of gesture GE 1  is a gesture that can be judged just by the moving direction of a particular part of the body such as the hand  2 A. In contrast, the third type of gesture GE 3  cannot be judged just by the moving direction of a particular part of the body such as the hand  2 A, and cannot be judged without analyzing displacement of the particular part of the body. As above, the second type of gesture GE 2  is a gesture that is slightly hard to recognize, and the third type of gesture GE 3  is a gesture that is the most hard to recognize. 
     When the distance D 0  is less than or equal to the first set distance D 1  (i.e., when the information display device  1  is in the full-function mode), the operator  2  can use any type of gesture GE 1 , GE 2  or GE 3  for operating the information display device  1  by gesture. When the distance D 0  is greater than the first set distance D 1  and less than or equal to the second set distance D 2  (i.e., when the state of the information display device  1  is the limited function mode), the operator  2  can use the first type of gesture GE 1  and the second type of gesture GE 2  but cannot use the third type of gesture GE 3 . When the distance D 0  is over the second set distance D 2  (i.e., when the state of the information display device  1  is the specified function mode), the operator  2  can use the first type of gesture GE 1  but cannot use the second type of gesture GE 2  or the third type of gesture GE 3 . 
       FIG. 5  is a diagram showing an example of the image displayed on a screen  31  of the display unit  30  of the information display device  1  according to the first embodiment.  FIG. 5  shows an example of the display content when the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) is less than or equal to the first set distance D 1 . In this case, currently viewed program images  301  based on video content are displayed on the entire screen  31  of the display unit  30 . Further, a “MENU” icon  302  is displayed in a lower left part of the screen  31 . Here, the display shown in  FIG. 5  shifts to display content including an operation menu ( FIG. 6 ) when the information display device  1  identifies a predetermined gesture performed by the operator  2  (gesture as a command to shift to the display content including the operation menu) or when the operator  2  performs an operation for selecting the “MENU” icon  302 . 
       FIG. 6  is a diagram showing another example of the image displayed on the screen  31  of the display unit  30  of the information display device  1  according to the first embodiment.  FIG. 6  shows an example of the display content when the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) is less than or equal to the first set distance D 1 .  FIG. 6  shows the display content after shifting from the display content of  FIG. 5 . In  FIG. 6 , the screen  31  is divided into four regions. In an upper left region of the screen  31 , the currently viewed program images  301  based on video content are displayed. In an upper right region of the screen  31 , content information  303  indicating information on the currently viewed program images  301  is displayed. In a lower left region of the screen  31 , content setting information  304  as an operation menu is displayed. In a central lower right region of the screen  31 , application menu information  305  as an operation menu is displayed. The content setting information  304  includes operation information regarding the currently viewed program images  301 , that is, information on channel switching, volume control, recording/playback, image quality/tone control, communication method, and so forth. The application menu information  305  indicates information including icons for making a selection from applications the information display device  1  has. A “RETURN TO PROGRAM” icon  306  is an icon for shifting from the display content of  FIG. 6  to the display content of  FIG. 5 . 
     When the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) is less than or equal to the first set distance D 1 , the information display device  1  is in the full-function mode. The content setting information  304  and the application menu information  305 , as the operation menus shown in  FIG. 6 , are information regarding functions that the operator  2  can operate in the full-function mode. 
     The icons, characters and pointer displayed on the screen  31  of the display unit  30  can be configured so as be small in size when the distance D 0  is short and increase in size with the increase in the distance D 0 . This configuration allows the operator  2  to recognize that the information display device  1  currently grasps the distance between the operator  2  and the information display device  1 . In other words, the fact that the information display device  1  currently recognizes the distance D 0  can be fed back to the operator  2  through the sizes of the icons, characters, pointer, etc. 
     Incidentally, optimum sizes of the icons, characters and pointer on the screen  31  have previously been set on the information display device  1 . Thus, settings have been made on the information display device  1  so that changing these sizes will not cause a change impairing visibility such as collapsed layout of multiple pieces of information on the screen  31  or an icon, character or pointer sticking out from the display region on the screen  31 . 
       FIG. 7  is a diagram showing another example of the image displayed on the screen  31  of the display unit  30  of the information display device  1  according to the first embodiment.  FIG. 7  shows an example of the display when the distance D 0  is greater than the first set distance D 1  and less than or equal to the second set distance D 2 . In this case, the region of the screen  31  is not divided. The currently viewed program images  301  based on video content are displayed in the entire region of the screen  31  as background images. The application menu information  305  is displayed in the entire region of the screen  31  on the currently viewed program images  301  displayed as the background. 
     When the distance D 0  is greater than the first set distance D 1  and less than or equal to the second set distance D 2 , the information display device  1  is in the function limitation mode. In the function limitation mode, the functions the operator  2  can operate by gesture are limited to functions of a high frequency of use. The operation information regarding the currently viewed program images  301  is about functions of a low frequency of use by the operator  2 . Thus, the content setting information  304  shown in  FIG. 6  is not displayed in the function limitation mode as shown in  FIG. 7 . Further, the content information  303  shown in  FIG. 6  is also not displayed in the function limitation mode as shown in  FIG. 7  since the content information  303  is not necessarily information of a high frequency of use by the operator  2 . Incidentally, the “MOVIE” icon  305 A in  FIG. 7  is an icon for making the information display device  1  display video content of a movie.  FIG. 7  shows a state in which the “MOVIE” icon  305 A has been selected with an arrow as a pointer. 
     As above, in the function limitation mode, information of a low frequency of use by the operator  2  is not displayed on the display unit  30  and the application menu information  305  of a high frequency of use by the operator  2  is displayed large on the entire screen  31  of the display unit  30 . Thus, the operator  2  can visually recognize the display content on the display unit  30  even when the operator  2  is far from the display unit  30 . Further, since information of a high frequency of use is displayed, operability of the information display device  1  can be maintained when the operator  2  operates the information display device  1 . 
     Incidentally, the display content on the display unit  30  in the function limitation mode is not limited to the application menu information  305 . For example, the operator  2  may be allowed to previously select items to be used frequently and assign ranks to the selected items, and the information display device  1  may determine the display content on the display unit  30  based on information on the ranks. 
     It is also possible for the information display device  1  to count operation items used in gestures by the operator  2 , store the result of the counting, and thereby determine the content displayed in the function limitation mode. 
       FIG. 8  is a diagram showing another example of the image displayed on the screen  31  of the display unit  30  of the information display device  1  according to the first embodiment. The “MOVIE” icon  305 B in the selected state in  FIG. 8  is displayed with a thick frame instead of being selected with the pointer (arrow). As in this example, the display of the selected icon can be changed depending on the distance D 0 . It is also possible to employ a configuration in which the size of the “MOVIE” icon  305 A ( 305 B) or other icons, characters, etc. included in the application menu information  305  is changed depending on the distance D 0 . 
       FIG. 9  is a diagram showing another example of the image displayed on the screen  31  of the display unit  30  of the information display device  1  according to the first embodiment.  FIG. 9  shows an example of the image displayed on the screen  31  of the display unit  30  when the distance D 0  is over the second set distance D 2 . In the example shown in  FIG. 9 , the currently viewed program images  301  based on video content are displayed on the entire screen  31  of the display unit  30 . 
     When the distance D 0  is over the second set distance D 2 , the information display device  1  is in the specified function mode. In the specified function mode, the functions that the operator  2  can operate by gesture are limited to functions of a still higher frequency of use, such as channel switching, volume change, etc. in regard to the video content currently viewed by the operator  2 . Thus, in the specified function mode, the “MENU” icon  302  ( FIG. 5 ) for shifting to the display content including the operation menu is not displayed on the screen  31  of the display unit  30 . As above, the functions of the information display device  1  are limited to functions of a high frequency of use by the operator  2  and information of a low frequency of use by the operator  2  is not displayed on the display unit  30 . As explained above, even when the operator  2  is situated still farther from the display unit  30 , unnecessary information is not displayed and thus it is possible to avoid a situation in which it is hard for the operator to visually recognize the display content on the display unit  30 . 
       FIGS. 10( a ) and 10( b )  are diagrams showing transition of the display content by the information display device  1  according to the first embodiment.  FIGS. 10( a ) and 10( b )  show the transition of the display content on the display unit  30  of the information display device  1  when the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) is less than or equal to the first set distance D 1 . The display content on the display unit  30  in  FIG. 10( a )  is identical with the display content on the display unit  30  shown in  FIG. 5 . The display content on the display unit  30  shown in  FIG. 10( b )  is identical with the display content on the display unit  30  shown in  FIG. 6 . When the operator  2  selects the “MENU” icon  302  on the display unit  30  in  FIG. 10( a )  by making a gesture, the display content on the display unit  30  shifts from the display content in  FIG. 10( a )  to the display content in  FIG. 10( b ) . When the operator  2  selects the “RETURN TO PROGRAM” icon  306  ( FIG. 6 ) by making a gesture, the display content on the display unit  30  shown in  FIG. 10( b )  shifts to the display content on the display unit  30  shown in  FIG. 10( a ) . 
       FIGS. 11( a ) and 11( b )  are diagrams showing transition of the display content by the information display device  1  according to the first embodiment.  FIGS. 11( a ) and 11( b )  show the transition of the display content on the display unit  30  of the information display device  1  when the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) is greater than the first set distance D 1  and less than or equal to the second set distance D 2 . The display content on the display unit  30  in  FIG. 11( a )  is identical with the display content on the display unit  30  shown in  FIG. 5 . The display content on the display unit  30  shown in  FIG. 11( b )  is identical with the display content on the display unit  30  shown in  FIG. 7 . When the operator  2  selects the “MENU” icon  302  shown in  FIG. 5  by making a gesture, the display content on the display unit  30  shown in  FIG. 11( a )  shifts to the display content on the display unit  30  shown in  FIG. 11( b ) . When the operator  2  selects the “RETURN TO PROGRAM” icon  306  shown in  FIG. 7  by making a gesture, the display content on the display unit  30  shown in  FIG. 13( b )  shifts to the display content on the display unit  30  shown in  FIG. 11( a ) . 
       FIGS. 12( a ) to 12( c )  are schematic diagrams showing usage status of the information display device  1  according to the first embodiment.  FIG. 12( a )  shows the display content on the display unit  30  of the information display device  1  when the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) is over the second set distance D 2 .  FIGS. 12( b ) and 12( c )  show an example of gestures made by the operator  2 . The display content on the display unit  30  in  FIG. 12( a )  is identical with the display content on the display unit  30  in  FIG. 9 . As shown in  FIG. 11( b ) , to switch the channel, the operator  2  performs a left/right swipe (moves the hand  2 A to the left or right in an arrow direction). To adjust the sound volume, the operator  2  performs an up/down swipe (moves the hand  2 A upward or downward in an arrow direction). 
     As above, it becomes possible for the operator  2  to operate the functions of a high frequency of use, channel switching and volume control, by just making a gesture without using an operation menu displayed on the display unit  30 . Further, the swipe, as the gesture used in this case, is a gesture easily identified by the information display device  1 . Thus, even when the distance between the operator  2  and the information display device  1  is long, the possibility of erroneous identification by the information display device  1  can be reduced. 
     Incidentally, when the distance D 0  is over the second set distance D 2 , the functions the operator  2  can operate are not limited to channel switching and volume control. However, the functions the operator  2  can operate are desired to be not those identified by the displacement of the operator  2 &#39;s particular body part such as the hand  2 A but those identified by the moving direction. 
       FIG. 13  is a flowchart showing an initial setting of the information display device  1  according to the first embodiment. The information display device  1  sets the first set distance D 1  (step S 1 ). The information display device  1  captures an image of the hand  2 A, the fingers  2 B, the face  2 C, etc. of the operator  2  situated at a position the first set distance D 1  from the gesture detection unit  10  (or the display unit  30 ) by use of the gesture detection unit  10  and stores the sizes of the hand  2 A, the fingers  2 B, the face  2 C, etc. included in the captured image. Here, the data the information display device  1  stores are the area, the vertical length Lv, the horizontal length Lh, etc. of each of the detection regions, when the hand  2 A, the fingers  2 B and the face  2 C are determined as the detection regions as shown as the detection region  201  in  FIG. 3 . Subsequently, the information display device  1  sets the second set distance D 2  (step S 2 ). Similarly to the step S 1 , the information display device  1  captures an image of the operator  2  situated at a position the second set distance D 2  from the gesture detection unit  10  (or the display unit  30 ) and stores the area of the detection region and the like. 
       FIG. 14  is a flowchart showing the operation of the information display device  1  according to the first embodiment. The gesture detection unit  10  starts the gesture image capturing (detection) triggered by a predetermined gesture performed by the operator  2  (step S 10 ). The predetermined gesture may be either a pose by the hand  2 A or a motion by the hand  2 A. The gesture detection unit  10  captures images of the operator  2 &#39;s gesture and generates image data. Incidentally, while it is assumed in the following explanation that only the operator is image-captured in the generated image data, the present invention is not restricted to this example. The present invention is applicable also to cases where multiple people are included in the image data. In cases where multiple people are included in the image data, it is possible to employ a method of carrying out the gesture recognition for a person whose predetermined body part is detected first among the people or a method of carrying out the gesture recognition for all of the people, for example. 
     Subsequently, the information display device  1  judges whether the initial setting shown in  FIG. 13 , that is, the setting of the first set distance D 1  and the second set distance D 2  (steps S 1  and S 2 ), has been completed (step S 11 ). If the initial setting has not been made, the information display device  1  makes the initial setting shown in  FIG. 13  (step S 12 ). 
     Subsequently, the distance estimation unit  21  estimates the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) (step S 13 ). The information display device  1  advances the process to step S 15  if the distance D 0  is less than or equal to the first set distance D 1 , advances the process to step S 16  if the distance D 0  is greater than the first set distance D 1  and less than or equal to the second set distance D 2 , or advances the process to step S 17  if the distance D 0  is over the second set distance D 2  (step S 14 ). 
     In the case where the distance D 0  is less than or equal to the first set distance D 1 , the identification function setting unit  22  sets the operational state of the information display device  1  in the full-function mode (step S 15 ). In the case where the distance D 0  is greater than the first set distance D 1  and less than or equal to the second set distance D 2 , the identification function setting unit  22  sets the operational state of the information display device  1  in the function limitation mode (step S 16 ). In the case where the distance D 0  is over the second set distance D 2 , the identification function setting unit  22  sets the operational state of the information display device  1  in the specified function mode (step S 17 ). 
     Subsequently, the display control unit  25  changes the layout of displaying the video content and the operation menu based on the operational state of the information display unit  1   a  and has the display unit  30  make the display. Further, the display control unit  25  adjusts the sizes of the characters, icons and pointer displayed on the display unit  30  based on the distance D 0  (step S 18 ). 
     The gesture identification unit  23  makes the gesture identification based on the motion pattern the operator  2 &#39;s gesture shows and the identifiable gestures limited by the identification function setting unit  22  (step S 19 ). The gesture identification unit  23  judges the operator  2 &#39;s command content by referring to the gesture DB  40   a . In this case, when the time necessary for the gesture identification exceeds a time limit or the operator  2  operates the information display device  1  by using a remote control or the like, the gesture identification unit  23  stops the gesture identification process (step S 22 ). 
     When the command content of the operator  2 &#39;s gesture has been judged, the function execution unit  24  executes a function based on the command content (step S 20 ). 
     The information display device  1  judges whether the operator  2 &#39;s operation by gesture ends or not (step S 21 ). If the operator  2 &#39;s operation exists (NO in the step S 21 ), the gesture identification unit  23  makes the identification of the operator  2 &#39;s gesture. 
     &lt;1-3&gt; Effect 
     As described above, in the information display device  1  according to the first embodiment, the identifiable gestures are set so that the number of the identifiable gestures becomes small when the operator  2  is situated at a position far from the display unit  30  of the information display device  1  (e.g., position farther than the first set distance D 1 ). As above, by the information display device  1  according to the first embodiment, when the operator  2  is situated at a position far from the display unit  30 , erroneous identification of the operator  2 &#39;s gesture can be made unlikely to occur by excluding gestures with a small body movement from the identifiable gestures, for example. 
     Further, in the information display device  1  according to the first embodiment, when the operator  2  is situated at a position far from the display unit  30  of the information display device  1  (e.g., position farther than the first set distance D 1 ), the identifiable gestures are limited to gestures for functions of a high frequency of use. As above, by the information display device  1  according to the first embodiment, when the operator  2  is situated at a position far from the display unit  30 , the identifiable gestures are reduced in number (e.g., limited to gestures regarding functions of a high frequency of use by the operator), by which erroneous identification of the operator  2 &#39;s gesture can be made unlikely to occur. 
     Furthermore, in the information display device  1  according to the first embodiment, when the operator  2  is situated at a position far from the display unit  30  of the information display device  1  (e.g., position farther than the first set distance D 1 ), the layout of the image displayed on the display unit  30  is changed and the operation menu including icons, characters, pointer, etc. is displayed in an enlarged view. As above, by the information display device  1  according to the first embodiment, even when the operator  2  is situated at a position far from the display unit  30 , the operation menu is displayed in an enlarged view, which inhibits deterioration in viewability of the display content on the display unit  30  (visibility) for the operator  2  and easiness of operation (operability) for the operator  2 . 
     In the above explanation, an example of switching the operational state by using the first set distance D 1  and the second set distance D 2  has been described. However, the information display device  1  may also employ a method using only one of the first and second set distances D 1  and D 2  or a method using three or more set distances. 
     &lt;2&gt; Second Embodiment 
     In the first embodiment, when the operator  2 &#39;s gesture is not identified (judged) by the information display device  1 , the gesture identification process by the information display device  1  stops (the step S 22  in  FIG. 14 ) and the operation by gesture is performed again. In contrast, in the second embodiment, the fact that the gesture is not identified is displayed on the display unit  30 . Incidentally, the configuration of the information display device in the second embodiment is the same as the configuration of the information display device  1  according to the first embodiment. Thus,  FIG. 1  is also referred to in the following description of the second embodiment. 
       FIG. 15  is a flowchart showing the operation of the information display device according to the second embodiment of the present invention. In  FIG. 15 , processing steps identical with those shown in  FIG. 14  are assigned the same reference characters as in  FIG. 14 . 
     The gesture identification unit  23  performs the gesture identification based on the motion pattern the operator  2 &#39;s gesture shows and the identifiable gestures limited by the identification function setting unit  22  (step S 19 ). In the second embodiment, when it is impossible to judge the command content from the operator  2 &#39;s gesture, a process corresponding to the cause of the impossibility is performed. When the gesture performed by the operator  2  is judged to have no corresponding reference gesture included in the reference gestures stored in the gesture DB  40   a , the gesture identification unit  23  notifies the display control unit  25  via the function execution unit  24  that the operator  2 &#39;s gesture is unidentifiable. The display control unit  25  makes the display unit  30  display that the gesture is unidentifiable (step S 23 ). When the time necessary for the identification of the gesture exceeds the time limit or when the operator  2  operates the information display device  1  by using the remote control or the like, the gesture identification unit  23  stops the gesture identification process (step S 22 ). 
     As described above, in the second embodiment, when the gesture is not identified, the fact that the gesture is unidentifiable is displayed on the display unit  30 . The display by the display unit  30  allows the operator  2  to grasp that the gesture was not identified. Accordingly, the operator  2  can select performing the gesture again or operating the information display device  1  by using a device such as the remote control. Consequently, even when the operator  2 &#39;s gesture is not identified by the information display device  1 , the information display device  1  can be prevented from being recognized by the operator  2  to have significantly deteriorated in operability. 
     Incidentally, except for the features described above, the information display device and information display method according to the second embodiment are equivalent to the device and method according to the first embodiment. 
     &lt;3&gt; Third Embodiment 
     In the first embodiment, the gesture detection unit  10  was mounted on the main body of the information display device  1  (top part of the display unit  30 ). In a third embodiment, a description will be given of a case where the gesture detection unit is arranged at a position apart from an information display unit equipped with the display unit (display)  30 . 
       FIG. 16  is a schematic diagram showing usage status of an information display device  100  according to the third embodiment of the present invention. In  FIG. 16 , components identical or corresponding to those shown in  FIG. 1  (first embodiment) are assigned the same reference characters as in  FIG. 1 . As shown in  FIG. 16 , the information display device  100  includes an information display unit  1   a , having the display unit  30 , and a gesture detection unit  10   a . The operator  2  operates the information display unit  1   a  by making a gesture. In the third embodiment, the gesture detection unit  10   a  is arranged at a position apart from the information display unit  1   a , such as on a wall of a room. 
       FIG. 17  is a block diagram schematically showing the configuration of the information display device  100  according to the third embodiment. In  FIG. 17 , components identical or corresponding to those shown in  FIG. 2  (first embodiment) are assigned the same reference characters as in  FIG. 2 . As shown in  FIG. 17 , the information display device  100  includes the gesture detection unit  10   a  and the information display unit  1   a.    
     The gesture detection unit  10   a  includes an image capturing unit  13  and a transmission unit  11 . The image capturing unit  13  captures images of the operator  2 &#39;s gesture GE and generates image data. The transmission unit  11  transmits the image data generated by the image capturing unit  13  to a reception unit  12  of the information display unit  1   a.    
     The reception unit  12  of the information display unit  1   a  receives the image data transmitted from the transmission unit  11  of the gesture detection unit  10   a  and sends the received image data to the control unit  20 . The method of communication between the transmission unit  11  and the reception unit  12  may be either wired communication or wireless communication such as Bluetooth (registered trademark), infrared data communication or Wi-Fi communication, for example. 
     In the third embodiment, the gesture detection unit  10   a  is fixed at a position where the operator  2 &#39;s gesture can be detected. The information display unit  1   a  holds position information indicating the position where the gesture detection unit  10   a  is fixed (represented by XYZ coordinates, for example) and position information indicating the position of the display unit  30  of the information display unit  1   a  (represented by XYZ coordinates, for example). Therefore, the distance estimation unit  21  is capable of estimating (calculating) the distance between the operator  2  and the display unit  30  based on the aforementioned position information and the image data received from the reception unit  12 . The gesture identification unit  23  is capable of detecting the motion pattern by analyzing the displacement of a part of the operator  2 &#39;s body (detection region) included in the image data received from the reception unit  12 . 
     As above, even in cases where the gesture detection unit  10   a  is arranged at a position apart from the information display unit  1   a , the distance between the operator  2  and the display unit  30  can be estimated. Since the display content on the display unit  30  is changed depending on the estimated distance, the information display device  100  can maintain excellent operability when the operator  2  operates the information display unit  1   a.    
     Further, even in cases where the information display unit  1   a  is not equipped with the gesture detection unit  10 , the information display device according to the third embodiment can be formed by combining the information display unit  1   a  with the gesture detection unit  10  by updating the software of the information display unit  1   a . As above, the information display device according to the third embodiment is applicable also to conventional information display devices. 
     Incidentally, except for the features described above, the information display device and information display method according to the third embodiment are equivalent to the device and method according to the first or second embodiment. 
     &lt;4&gt; Fourth Embodiment 
     In the third embodiment, the description was given of a case where the gesture detection unit  10   a  is fixed at a predetermined position and the object of detection (image capturing) by the gesture detection unit  10   a  is the operator  2 . In the fourth embodiment, a description will be given of a case where an operating device as a gesture detection unit is attached to the body of the operator  2  performing the gesture (e.g., the operator holds the operating device in hand) and the object of the detection (image capturing) by the operating device as the gesture detection unit is the display unit of the information display device, for example. 
       FIG. 18  is a schematic diagram showing usage status of an information display device  100   a  according to the fourth embodiment of the present invention. In  FIG. 18 , components identical or corresponding to those shown in  FIG. 16  (third embodiment) are assigned the same reference characters as in  FIG. 16 . As shown in  FIG. 18 , the information display device  100   a  includes an information display unit  1   b , having the display unit  30 , and an operating device  10   b  as the gesture detection unit. The operator  2  inputs an operation signal to the reception unit  12  (shown in  FIG. 19  which will be explained later) of the information display unit  1   b  by performing a gesture with the operating device  10   b  attached to the operator  2 &#39;s body (e.g., held in hand). The operator  2  inputs the operation signal to the information display unit  1   b  by a gesture such as moving (swinging) the operating device  10   b  leftward, rightward, upward or downward or drawing a character or mark in the air with the operating device  10   b , for example. The shape and size of the operating device  10   b  are not limited to those shown in  FIG. 18 ; the operating device  10   b  may be in a different shape. 
       FIG. 19  is a block diagram schematically showing the configuration of the information display device  100   a  according to the fourth embodiment. In  FIG. 19 , components identical or corresponding to those shown in  FIG. 17  (third embodiment) are assigned the same reference characters as in  FIG. 17 . 
     The operating device  10   b  includes an image capturing unit  15  as a recognition sensor, a feature extraction unit  14 , and the transmission unit  11 . The image capturing unit  15  generates image data by capturing images of a region as the subject including the information display unit  1   b  while the operator  2  performs a gesture. The image capturing unit  15  is an RGB camera or a ToF sensor, for example. The RGB camera can be a camera mounted on a personal digital assistant or a mobile information terminal such as a smartphone in which software for implementing the function of communicating with the information display unit  1   b  has been installed. 
     The feature extraction unit  14  extracts features of the gesture performed by the operator  2  from the image data generated by the image capturing unit  15 . The features of the gesture are extracted as motion vectors of the operating device  10   b  (locus of the motion of the operating device  10   b ) by analyzing the displacement of an object, as a certain image-captured object included in the image data, in multiple pieces of still image data arranged in the order of time or video image data. The feature extraction unit  14  can use the display unit  30  of the information display unit  1   b  as the object included in the image data generated by the image capturing unit  15 . The feature extraction unit  14  sends information regarding the generated image data, the features of the gesture and the region of the display unit  30  to the transmission unit  11 . 
     The transmission unit  11  transmits the information regarding the generated image data, the features of the gesture and the region of the display unit  30  of the information display unit  1   b  towards the reception unit  12  of the information display unit  1   b.    
     As described above, the information display device  100   a  according to the fourth embodiment is capable of estimating the distance between the operator  2  and the display unit  30  when the operator  2  performs a gesture while holding the operating device  10   b  in hand. Since the display content is changed depending on the estimated distance, the information display device  100   a  can maintain operability for the operator operating the information display device. 
     Further, similarly to the third embodiment, even in cases where the information display unit  1   b  is not equipped with the image capturing unit  15 , the information display device according to the fourth embodiment can be formed by combining the information display unit  1   b  with the image capturing unit  15  and updating the software of the information display unit  1   b . As above, the information display device according to the fourth embodiment is applicable to conventional information display devices. 
     Incidentally, except for the features described above, the information display device and information display method according to the fourth embodiment are equivalent to the device and method according to the third embodiment. 
     &lt;5&gt; Fifth Embodiment 
     In the first to fourth embodiments, when the image data generated by the information display device  1  is influenced by external disturbance such as vibration, illumination and natural light (external light) due to the environment of the place where the operator  2  performs the gesture operation (e.g., condition of illumination and condition of natural light) and the environment of the place where the information display device  1  (or the information display unit  1   a  or  1   b ) is installed (e.g., condition of illumination and condition of natural light), the possibility of erroneous recognition of the operator  2 &#39;s gesture operation by the information display device  1  increases. In contrast, an information display device  1   c  according to a fifth embodiment includes an external disturbance detection unit  26 , thereby inhibits the erroneous recognition due to the influence of external disturbance, and improves the operability of the information display device  1   c  operated by the gesture operation. In the following, the information display device  1   c  according to the fifth embodiment and an information display device  1   d  according to a modification of the fifth embodiment will be described with reference to  FIGS. 20 and 21 . 
       FIG. 20  is a block diagram schematically showing the configuration of the information display device  1   c  according to the fifth embodiment of the present invention. In  FIG. 20 , components identical or corresponding to those shown in  FIG. 2  (first embodiment) are assigned the same reference characters as in  FIG. 2 . As shown in  FIG. 20 , the information display device  1   c  according to the fifth embodiment differs from the information display device  1  according to the first embodiment in that a control unit  20   c  includes the external disturbance detection unit  26  and in the processing performed by a distance estimation unit  21   c  of the control unit  20   c.    
     The external disturbance detection unit  26  detects a movement in the multiple frames of images (multiple pieces of image data) G 1  generated by the image capturing by the gesture detection unit  10 , and when a regular movement in a certain predetermined period is included in the detected movement, judges the regular movement as the external disturbance (e.g., vibration, change in the condition of illumination, change in the condition of natural light, or the like) and generates filter information G 5  based on the judgment (information to be used for a process for removing the influence of the external disturbance). 
     The filter information G 5  generated by the external disturbance detection unit  26  is sent to the distance estimation unit  21   c . The distance estimation unit  21   c  compensates for the movement in the multiple frames of images (multiple pieces of image data) G 1  based on the filter information G 5  received from the gesture detection unit  10 . More specifically, the distance estimation unit  21   c  generates multiple frames of images (multiple pieces of image data) G 3  with no influence of the external disturbance (or with reduced influence of the external disturbance) by removing components of the regular movement as the influence of the external disturbance from the multiple frames of images (multiple pieces of image data) G 1 . 
       FIG. 21  is a block diagram schematically showing the configuration of the information display device  1   d  according to the modification of the fifth embodiment. In  FIG. 21 , components identical or corresponding to those shown in  FIG. 20  are assigned the same reference characters as in  FIG. 20 . As shown in  FIG. 21 , the information display device  1   d  differs from the information display device  1   c  according to the fifth embodiment in including an external disturbance detection unit  26   d  as a component outside a control unit  20   d . The control unit  20   d  of the information display device  1   d  performs the same control as the control unit  20   c  of the information display device  1   c.    
     The external disturbance detection unit  26   d  detects a movement in the multiple frames of images (multiple pieces of image data) G 1  generated by the image capturing by the gesture detection unit  10 , and when a regular movement in a certain predetermined period is included in the detected movement, judges the regular movement as the external disturbance (e.g., acceleration, vibration, inclination, change in the condition of illumination, change in the condition of natural light, or the like) and generates filter information G 5  based on the judgment (information to be used for the process for removing the influence of the external disturbance). As above, the external disturbance detection unit  26   d  is a unit newly provided outside the control unit  20   d , and can be, for example, an acceleration sensor, a vibration sensor, an inclination sensor, an optical sensor or the like capable of detecting the external disturbance such as acceleration, vibration, inclination, the condition of illumination, the condition of natural light, or the like. 
     The filter information G 5  generated by the external disturbance detection unit  26   d  is sent to the distance estimation unit  21   d . The distance estimation unit  21   d  compensates for the movement in the multiple frames of images (multiple pieces of image data) G 1  based on the filter information G 5  received from the gesture detection unit  10 . More specifically, the distance estimation unit  21   d  generates multiple frames of images (multiple pieces of image data) G 3  with no influence of the external disturbance (or with reduced influence of the external disturbance) by removing components of the regular movement as the influence of the external disturbance from the multiple frames of images (multiple pieces of image data) G 1 . 
       FIG. 22  is a flowchart showing the operation of the information display devices  1   c  and  1   d  in the fifth embodiment. In  FIG. 22 , processing steps identical with those shown in  FIG. 14  (first embodiment) are assigned the same reference characters as in  FIG. 14 . The process shown in  FIG. 22  differs from the process shown in  FIG. 14  in including steps S 24  and S 25 . A principal part of the operation of the information display device  1   c  will be described below with reference to  FIG. 22 . 
     As shown in  FIG. 22 , the gesture detection unit  10  starts the gesture image capturing (detection) triggered by a predetermined gesture performed by the operator  2  (step S 10 ). 
     Subsequently, the external disturbance detection unit  26  performs an external disturbance detection process (step S 24 ). When external disturbance is detected by the external disturbance detection unit  26  (YES in the step S 24 ), the distance estimation unit  21   c  compensates for the influence of the external disturbance by removing components of a regular movement due to the external disturbance from the image data G 1  (step S 25 ). When no external disturbance is detected by the external disturbance detection unit  26  (NO in the step S 24 ), the distance estimation unit  21   c  advances the process to the step S 11  without performing the process of compensating for the influence of the external disturbance. The processing from the step S 11  is the same as the processing shown in  FIG. 14  (first embodiment). 
     Incidentally, while the external disturbance detection (step S 24 ) is performed after starting the gesture detection (step S 10 ) in the flowchart shown in  FIG. 22 , it is also possible to start the gesture detection (step S 10 ) after performing the external disturbance detection (step S 24 ). 
     Except for the features described above, the information display device  1   c  and information display method according to the fifth embodiment are equivalent to the devices and methods according to the first to fourth embodiments. Except for the features described above, the information display device  1   d  and information display method according to the modification of the fifth embodiment are equivalent to the devices and methods according to the first to fourth embodiments. 
     By the information display devices  1   c  and  1   d  and the information display methods according to the fifth embodiment, the influence of the external disturbance can be lessened, and thus the accuracy of the gesture recognition can be increased. 
     &lt;6&gt; Sixth Embodiment 
     In the first to fifth embodiments, the description was given of configurations for detecting the gesture with the gesture detection unit  10  and measuring the distance without identifying the operator  2 . In contrast, in a sixth embodiment, a description will be given of a case where an operator recognition unit  27  identifies (recognizes) the operator  2  performing the gesture operation from the images (image data) G 1  generated by the gesture detection unit  10  and the distance is measured by using previously registered size information on the operator  2 &#39;s body part. 
       FIG. 23  is a block diagram schematically showing the configuration of an information display device  1   e  according to the sixth embodiment of the present invention. In  FIG. 23 , components identical or corresponding to those shown in  FIG. 2  (first embodiment) are assigned the same reference characters as in  FIG. 2 . As shown in  FIG. 23 , the information display device  1   e  differs from the information display device  1  according to the first embodiment in that a control unit  20   e  includes the operator recognition unit  27  and in the processing performed by a distance estimation unit  21   e  of the control unit  20   e.    
     The operator recognition unit  27  previously stores a face image (face image data) of the operator  2  and attribute information on the operator  2  while associating (linking) them with each other when the initial setting information (the predetermined first set distance D 1  and second set distance D 2 ) is stored in the identification function setting unit  22 . The attribute information stored in the operator recognition unit  27  includes information for judging attributes of the operator  2 , such as adult or child, male or female, age range (age), and nationality. The attribute information may be either information estimated from a body part captured in an image generated by the image capturing by the gesture detection unit  10 , such as the face, physique, hand size and skin color registered at the time of initial setting, or information selected by the operator  2  at the time of setting. 
     The display content and the sizes of characters, icons and pointer controlled by the display control unit  25  can be changed according to the attribute information on the operator  2  stored in the operator recognition unit  27  and the distance information estimated by the distance estimation unit  21   e.    
       FIG. 24  is a flowchart showing the operation of the information display device  1   e  according to the sixth embodiment. In  FIG. 24 , processing steps identical with those shown in  FIG. 14  are assigned the same reference characters as in  FIG. 14 . The process shown in  FIG. 24  differs from the process shown in  FIG. 14  in including steps S 26 , S 27  and S 28 . A principal part of the operation of the information display device  1   e  will be described below with reference to  FIG. 24 . 
     As shown in  FIG. 24 , the gesture detection unit  10  starts the gesture image capturing (detection) triggered by a predetermined gesture performed by the operator  2  (step S 10 ). Subsequently, the information display device  1   e  judges whether the initial setting shown in  FIG. 13 , that is, the setting of the first set distance D 1  and the second set distance D 2  (steps S 1  and S 2 ), has been completed (step S 11 ). If the initial setting has not been made, the information display device  1   e  makes the initial setting shown in  FIG. 13  (step S 12 ). 
     Subsequently, when the gesture detection is started and the initial setting including the operator registration is confirmed to have been made (steps S 10 , S 11  and S 12 ), the operator recognition unit  27  performs the operator recognition process (step S 26 ). When the operator  2  is recognized (YES in the step S 26 ), the operator recognition unit  27  makes a setting of the operator  2  and sends display setting information G 4  based on the setting of the operator  2  and the image data G 1  to the distance estimation unit  21   e  (step S 27 ). When the operator  2  cannot be recognized (NO in the step S 26 ), the operator recognition unit  27  sets guest setting information and sends the guest setting information and the image data G 1  to the distance estimation unit  21   e  (step S 28 ). 
     Subsequently, the distance estimation unit  21   e  estimates the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) (step S 13 ). The processing after the step S 13  in  FIG. 24  is the same as the processing after the step S 13  shown in  FIG. 14  (first embodiment). 
     As above, identification information on the operator  2  can also be displayed on the display unit  30  by performing the process of identifying (determining) the operator  2  with the operator recognition unit  27  and performing the process in the distance estimation unit  21   e  based on the attribute information on the operator  2  and the image data G 1 . In this case, even when there are multiple people at positions at the same distance from the information display device  1   e , which one of the people has been recognized as the operator  2  by the information display device  1   e  can be indicated to the operator  2  himself/herself. Accordingly, the operator  2  can obtain excellent operability in the gesture operation of the information display device  1   e.    
     By the information display device  1   e  and information display method according to the sixth embodiment, even when there are multiple people, the gesture recognition can be performed while identifying the operator  2 , by which the accuracy of the gesture recognition can be increased. 
     Except for the features described above, the information display device  1   e  and information display method according to the sixth embodiment are equivalent to the devices and methods according to the first to fourth embodiments. 
     &lt;7&gt; Seventh Embodiment 
     In the first to fourth embodiments, the distance estimation unit  21  estimates the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) based on the gesture information G 1  outputted from the gesture detection unit  10 , but does not judge whether the operator  2  is situated on the left side or on the right side of the gesture detection unit  10  (or the display unit  30 ). In contrast, as shown in  FIG. 25 , an information display device  1   f  according to a seventh embodiment judges not only the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) but also whether the operator  2  is situated on the left side or on the right side of a front center position of the gesture detection unit  10  (or the display unit  30 ). Namely, the information display device  1   f  has a function of judging whether the operator  2  is situated on the left side or the right side of the front center position of the gesture detection unit  10  when there are two people (the operator  2  and another person  3 ). 
       FIG. 26  is a block diagram schematically showing the configuration of the information display device  1   f  according to the seventh embodiment of the present invention. In  FIG. 26 , components identical or corresponding to those shown in  FIG. 2  (first embodiment) are assigned the same reference characters as in  FIG. 2 . As shown in  FIG. 23 , the information display device  1   e  differs from the information display device  1  according to the first embodiment in that a distance estimation unit  21   f  of a control unit  20   f  includes a left/right judgment unit  21   fa  and in the processing performed by the distance estimation unit  21   f  of the control unit  20   f.    
     The left/right judgment unit  21   fa  judges whether a detection region (where the operator  2  is detected) in each frame image captured and generated by the gesture detection unit  10 , namely, the operator  2 , is situated in a region on the left side or in a region on the right side when the image is divided into two regions on the left side and the right side. By this process, the left/right judgment unit  21   fa  can judge in which of the left-side region or the right-side region, obtained by dividing the frame image into the left side and the right side, the operator  2  is situated. 
     By using the position of the gesture detection unit  10  or the display unit  30  as the reference, the left/right judgment unit  21   fa  is capable of measuring the distance from the gesture detection unit  10  to the operator  2  and judging whether the operator  2  is situated on the left side or the right side in the case where the frame image is divided into the left side and the right side. For example, the left/right judgment unit  21   fa  is capable of judging whether the operator  2  in an in-car space is the driver seated on the driver seat (on the left side as viewed from the gesture detection unit  10  in cases of a car with the steering wheel on the right side), a person seated on the passenger seat (on the right side as viewed from the gesture detection unit  10  in cases of a car with the steering wheel on the right side), or a person seated on the rear seat (on the right side or the left side of the rear seat as viewed from the gesture detection unit  10 ). 
       FIG. 27  is a flowchart showing the operation of the information display device according to the seventh embodiment of the present invention. In  FIG. 27 , processing steps identical with those shown in  FIG. 14  are assigned the same reference characters as in  FIG. 14 . The process shown in  FIG. 27  differs from the process shown in  FIG. 14  in including steps S 29  and S 30  and in performing either a process of steps S 14 , S 15 , S 16  and S 17  or a process of steps S 14   a , S 15   a , S 16   a  and S 17   a  depending on judgment result of the step S 30 . A principal part of the operation of the information display device  1   f  will be described below with reference to  FIG. 27 . 
     As shown in  FIG. 27 , the gesture detection unit  10  starts the gesture image capturing (detection) triggered by a predetermined gesture performed by the operator  2  (step S 10 ). Subsequently, the information display device  1   f  judges whether the initial setting shown in  FIG. 13 , that is, the setting of the first set distance D 1  and the second set distance D 2  (steps S 1  and S 2 ), has been completed (step S 11 ). If the initial setting has not been made, the information display device  1  makes the initial setting shown in  FIG. 13  (step S 12 ). 
     Subsequently, the distance estimation unit  21   f  estimates the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) (step S 13 ). After the estimation of the distance D 0  (step S 13 ), the left/right judgment unit  21   fa  judges whether the operator  2  is situated on the left side or the right side as viewed from the display unit  30  based on a frame image captured and generated by the gesture detection unit  10   a  (step S 29 ). 
     When the judgment can be made on whether the operator  2  is situated on the left side or the right side as viewed from the display unit  30 , the information display device  1   f  shifts to a mode on the left side based on the distance D 0  or a mode on the right side based on the distance D 0  (step S 30 ). Incidentally, when the judgment cannot be made on whether the operator  2  is situated on the left side or the right side as viewed from the display unit  30 , a predetermined process (e.g., the steps S 14 -S 17  or the steps S 14   a -S 17   a ) may be selected and the fact that the judgment cannot be made may be reported to the display control unit  25  and displayed on the display unit  30 . Further, the fact that the operator  2  is situated on the left side or the right side as viewed from the display unit  30 , or the fact that the judgment cannot be made, may be displayed on the display unit  30 . 
     In the information display device  1   f  according to the seventh embodiment, the distance estimation unit  21   f  includes the left/right judgment unit  21   fa , and the display content controlled by the display control unit  25  can be switched by, for example, judging whether the operator  2  is an operator  2  seated on the driver seat or an operator  2  seated on the passenger seat. For example, the information display device  1   f  may display all the operations allowing for the gesture operation on the display unit  30  in the case where the operator  2  is a person seated on the driver seat, and display only functions irrelevant to safety (limited functions) among the operations allowing for the gesture operation on the display unit  30  in the case where the operator  2  is a person seated on the passenger seat. 
     Subsequently, the distance estimation unit  21   f  estimates the distance D 0  between the operator  2  and the gesture detection unit  10  (or the display unit  30 ) (step S 13 ). Subsequently, when the distance estimation unit  21   f  judges that the operator  2  is situated on the left side in the steps S 29  and S 30 , the information display device  1   f  advances the process to the step S 15  if the distance D 0  is less than or equal to the first set distance D 1 , advances the process to the step S 16  if the distance D 0  is greater than the first set distance D 1  and less than or equal to the second set distance D 2 , or advances the process to the step S 17  if the distance D 0  is over the second set distance D 2  (step S 14 ). When the distance estimation unit  21   f  judges that the operator  2  is situated on the right side in the steps S 29  and S 30 , the information display device  1   f  advances the process to the step S 15   a  if the distance D 0  is less than or equal to the first set distance D 1 , advances the process to the step S 16   a  if the distance D 0  is greater than the first set distance D 1  and less than or equal to the second set distance D 2 , or advances the process to the step S 17   a  if the distance D 0  is over the second set distance D 2  (step S 14   a ). Incidentally, the steps S 15   a , S 16   a  and S 17   a  are equivalent to the steps S 15 , S 16  and S 17  except that the operator  2  is situated on the right side. 
     By the information display device  1   f  and information display method according to the seventh embodiment, it is possible to judge in which direction the operator  2  is situated as viewed from the information display device  1   f , and the contents of the operation (the display content on the display unit  30 ) can be switched depending on the judged direction (e.g., the left side or the right side). 
     Except for the features described above, the information display device  1   f  and information display method according to the seventh embodiment are equivalent to the devices and methods according to the first to fourth embodiments. 
     &lt;8&gt; Modifications 
       FIG. 28  is a hardware configuration diagram showing the configuration of a modification of the information display devices according to the first to seventh embodiments described above. The information display device according to each of the first to seventh embodiments can be implemented by use of a memory  91  as a storage device for storing a program as software and a processor  92  as an information processing unit for executing the program stored in the memory  91  (e.g., implemented by a computer). In this case, the storage unit  40  shown in  FIG. 2 ,  FIG. 17  and  FIG. 19  correspond to the memory  91  in  FIG. 28 , and the control unit  20  shown in  FIG. 2 ,  FIG. 17  and  FIG. 19  correspond to the processor  92  in  FIG. 28  for executing the program. It is also possible to implement part of the control unit  20  shown in  FIG. 2 ,  FIG. 17  or  FIG. 19  by the memory  91  and the processor  92  in  FIG. 28 . Incidentally, the present invention can be modified within the range not departing from the content of the present invention. 
     It is possible to combine some of the configurations of the information display devices according to the first to seventh embodiments described above. For example, it is possible to freely combine the external disturbance inhibition function in the fifth embodiment, the function of determining the distance by using the operator recognition result in the sixth embodiment, and the function of switching the display content depending on the direction of the operator (on the left side or the right side as viewed from the device) in the seventh embodiment. 
     INDUSTRIAL APPLICABILITY 
     The present invention is applicable to a variety of information display devices such as television sets, PCs, car navigation systems, rear seat entertainment systems (RSEs), and digital signage systems installed in facilities like stations and airports, for example. 
     DESCRIPTION OF REFERENCE CHARACTERS 
       1 ,  1   c ,  1   d ,  1   e ,  1   f : information display device,  1   a ,  1   b : information display unit,  2 : operator,  10 ,  10   a : gesture detection unit,  10   b : operating device,  11 : transmission unit,  12 : reception unit,  14 : feature extraction unit,  20 ,  20   c ,  20   d ,  20   e ,  20   f : control unit,  21 ,  21   c ,  21   d ,  21   e ,  21   f : distance estimation unit,  21   fa : left/right judgment unit,  22 : identification function setting unit,  23 : gesture identification unit,  24 : function execution unit,  25 : display control unit,  26 : external disturbance detection unit,  27 : operator recognition unit,  30 : display unit,  31 : screen.