Abstract:
A presentation device comprises an image capture portion for capturing an image of a subject and generating a raw image thereof; a detection portion adapted to analyze whether a first marker is present in the raw image, and if the first marker is present in the raw image, to detect an existing position of the first marker within the raw image; a storage portion for storing a positional relationship of a synthesis position at which a mask image for masking at least a portion of the raw image is synthesized with the raw image relative to the existing position of the first marker; a synthesized image generation portion adapted to determine the synthesis position according to the positional relationship with the detected existing position, and to synthesize the mask image at the determined synthesis position within the raw image to generate a synthesized image; and an output portion for outputting the synthesized image.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the priority based on Japanese Patent Application No. 2009-174855 filed on Jul. 28, 2009, the disclosure of which is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a presentation device adapted to capture and generate an image of a document, and to display the image on an external display device. 
     2. Related Art 
     Certain conventional presentation devices, such as those disclosed in JP-A-2005-72744, JP-A-2004-20889, and JP-A-2002-94856, have a function for masking portions of a captured image. This function can be utilized, for example in the course of a lecture in a classroom, for the purpose of presenting an exam sheet to students while concealing the correct answers. 
     According to the prior art however, each time that the mask function is to be used, it is necessary to select an area for masking by operating a remote control or a control console on the unit, which makes operation cumbersome. Moreover, because the selected mask area is fixed over the image, if the document to be captured is moved, portions of the document may be masked or exposed unintentionally. 
     SUMMARY 
     An object of the present invention is to provide a presentation device that affords a more convenient masking process. 
     A first aspect of the invention is directed to a presentation device. The device includes an image capture portion for capturing an image of a subject and generating a raw image thereof; a detection portion adapted to analyze whether a first marker is present in the raw image, and if the first marker is present in the raw image, to detect an existing position of the first marker within the raw image; a storage portion for storing a positional relationship of a synthesis position at which a mask image for masking at least a portion of the raw image is synthesized with the raw image relative to the existing position of the first marker; a synthesized image generation portion adapted to determine the synthesis position according to the positional relationship with the detected existing position, and to synthesize the mask image at the determined synthesis position within the raw image to generate a synthesized image; and an output portion for outputting the synthesized image. 
     According to this aspect, if the first marker is present within the raw image, the mask image for masking at least a portion of the raw image is synthesized at the synthesis position having a predetermined relative positional relationship to the position of the first marker. Thus, even if the first marker shifts position within the raw image, the mask image in the output synthesized image shifts in association with this shift in position. As a result, it is possible for the user to accurately mask the desired portion, and to provide a presentation device that affords a more convenient masking process. 
     A second aspect of the invention is the presentation device according to the above aspect, wherein if the first marker is present in the raw image, the detection portion further detects the inclination of the first marker; and the synthesized image generation portion adjusts the synthesis position and the inclination of the mask image according to the detected inclination. According to this aspect, even if the subject is captured at a tilted angle, it is possible for the user to nevertheless accurately mask the desired portion. 
     A third aspect of the invention is the presentation device according to the above aspect, wherein if the first marker is present in the raw image, the detection portion further detects a size of the first marker; and the synthesized image generation portion adjusts the synthesis position and a size of the mask image according to the detected size. According to this aspect, if the subject is captured at enlarged or reduced magnification through optical zoom or the like, it is possible for the user to nevertheless accurately mask the desired portion. 
     A fourth aspect of the invention is the presentation device according to the above aspect, wherein the detection portion further analyzes whether a second marker different from the first marker is present in the raw image; and if the second marker is present in the raw image, the synthesized image generation portion executes a prescribed process in relation to the synthesis. According to this aspect, it is possible to carry out various different processes in relation to synthesis, according to whether the second marker is present on the subject. 
     A fifth aspect of the invention is the presentation device according to the above aspect, wherein if the second marker is present in the raw image, the synthesized image generation portion executes as the prescribed process a process to erase the mask image from the synthesized image. According to this aspect, if the first marker is present on the subject, the mask image can be easily erased by positioning the second marker on the subject. 
     Besides the aspect of a presentation device described above, the present invention in additional aspects thereof may be embodied as a method of control or a method of use of a presentation device; a computer program; or a recording medium having such a program recorded thereon. 
     These and other objects, features, aspects, and advantages of the invention will become more apparent from the following detailed description of the preferred embodiments with the accompanying drawings 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exterior view of a presentation device according to an embodiment of the invention; 
         FIG. 2  is a block diagram depicting internal configuration of the presentation device; 
         FIG. 3  is an illustration depicting an example of mask information; 
         FIG. 4  is a flowchart of a masking process; 
         FIG. 5  is an illustration depicting an example of a synthesized image displayed on a liquid crystal display; 
         FIG. 6  is an illustration depicting a display example in an instance in which a Create Mask marker is inclined at an angle; 
         FIGS. 7(   a ) and  7 ( b ) are drawings depicting a display method in an instance in which Create Mask marker size differs from the original size; and 
         FIG. 8  is a drawing depicting a display example in an instance in which an Erase Mask marker is detected in raw image data. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The aspects of the invention are described below based on the preferred embodiment, in the following order. 
     A. Presentation device Features: 
     B. Masking Process: 
     C. Modification: 
     A. Presentation Device Features 
       FIG. 1  is an exterior view of a presentation device  100  according to an embodiment of the invention. The presentation device  100  includes a base  102  adapted to be placed on a surface such as a desktop; a control console  103  provided on the base  102 ; an articulable support post  104  that extends upward from the base  102 ; and a camera head  106  mounted on the distal end of the support post  104 . The camera head  106  houses a CCD camera, and captures an image of a document ST (subject) that has been positioned on the desktop. A video output terminal  190  and a USB interface  195  are provided on the back face of the base  102 . The video output terminal  190  is used to connect a device such as a liquid crystal display  200 , a projector, or a television. A computer (not shown) is connected to the USB interface  195 . The video output terminal  190  and the USB interface  195  output the image of the document ST captured by the camera head  106 . 
     The presentation device  100  of the present embodiment has a function for synthesizing a prescribed mask image MI in the output image, according to whether a masking process marker MK is placed on the captured image ST. The features and process for carrying out this function are described in detail below. 
       FIG. 2  is a block diagram depicting internal configuration of the presentation device. The presentation device  100  includes an image capture module  120 , a frame memory  130 , a marker detection module  140 , a mask image generation module  150 , a synthesized image generation module  160 , an image output module  170 , an image encoding module  180 , a mask registration module  182 , and a flash memory  184 . Of these, the marker detection module  140 , the mask image generation module  150 , the synthesized image generation module  160 , the image output module  170 , the image encoding module  180 , and the mask registration module  182  are implemented through hardware, using ASICs (Application Specific Integrated Circuits). 
     The image capture module  120  includes a CCD camera housed inside the camera head  106 , and an analog front end circuit adapted to convert the analog signal output by the CCD camera to a digital signal. The image capture module  120  has an optical zoom function, and the magnification factor can be adjusted through operation of the control console  103 . The image capture module  120  takes a 15-frame image every second, and sequentially records the images as raw image data N 1  in the flash memory  130 . 
     The marker detection module  140  analyzes the raw image data N 1  recorded in the frame memory  130 , and ascertains whether an image representing a masking process marker MK is present therein. If a masking process marker MK is present, it then further identifies that class of the masking process marker MK. Classes of masking process markers MK are recorded in masking information INF that is recorded in the flash memory  184 . 
       FIG. 3  is an illustration depicting an example of masking information INF. In the present embodiment, several different types (three types in the present embodiment) of Create Mask markers MKa, MKb, MKc (first markers) and one type of Erase Mask marker (second marker) are included as classes of masking process markers MK. The masking information INF associates with each of the Create Mask markers MKa, MKb, MKc masking range data that indicates a range for masking to be performed when each Create Mask marker MKa, MKb, or MKc is placed on the document ST. This masking range data represents, in terms of relative coordinates from the current position of the Create Mask marker MKa, MKb, or MKc, a range over which masking is to be carried out.  FIG. 3  depicts an example in which the data representing rectangular areas is recorded as masking range data, but masking ranges could be other polygonal shapes besides rectangular, such as circular, triangular, or pentagonal. Also, several sets of masking range data may be associated with a single Create Mask marker. 
     If through analysis of the raw image data N 1 , the marker detection module  140  depicted in  FIG. 2  decides that the raw image data N 1  contains a Create Mask marker MKa, MKb, or MKc, it then identifies the class of the Create Mask marker (MKa-MKc), and detects the current position, inclination, and size of the Create Mask marker in the raw image data N 1 . Also, if through analysis of the raw image data N 1 , the marker detection module  140  decides that the raw image data N 1  contains the Erase Mask marker MKe, it outputs a signal to erase the mask image MI (hereinafter termed “erase signal”) to the synthesized image generation module  160 , discussed later. 
     In response to the class of Create Mask marker detected by the marker detection module  140 , the mask image generation module  150  reads the corresponding mask range data from the mask information INF. On the basis of the read mask range data, it then generates a mask image MI for hiding a portion of the raw image data N 1 . 
     The synthesized image generation module  160  then synthesizes the mask image MI that was generated by the mask image generation module  150  with the raw image data N 1  that was recorded to the frame memory  130 , to generate synthesized image data. The synthesized image data is then sent on to the image output module  170  and the image encoding module  180 . If an erase signal was received from the marker detection module  140 , the synthesized image generation module  160  does not carry out synthesis of the mask image with the raw image data N 1 , but instead sends the unmodified raw image data N 1  to the image output module  170  and the image encoding module  180 . 
     The image output module  170  performs D/A conversion and frame rate conversion of the synthesized image data or raw image data N 1  that was forwarded to it by the synthesized image generation module  160 , and outputs the data as an analog RGB signal from the video output terminal  190 . 
     The image encoding module  180  encodes to data of JPEG format the synthesized image data or raw image data N 1  that was sent to it by the synthesized image generation module  160 , and outputs the data from the USB interface  195 . The image encoding module  180  may be set up to perform encoding to JPEG data and output of JPEG data only when a computer is connected to the USB interface  195 . 
     Prior to execution of the masking process, described later, the mask registration module  182  receives mask range data entered by user through the control console  103 , and records the data in the masking information INF in the flash memory  184 . Specifically, using the control console  103  the user may for example specify a mask image MI range corresponding to a Create Mask marker, while verifying the position of the marker on the document ST which is displayed on the liquid crystal display  200 . The mask image MI range (mask range data) so specified is then associated with a class of Create Mask marker displayed on the liquid crystal display  200 , and is recorded to the masking information INF in the flash memory. 
     B. Masking Process 
       FIG. 4  is a flowchart of a masking process that is executed cooperatively by the blocks shown in  FIG. 2 . This masking process is executed repeatedly during the time that the presentation device  100  is powered on. When the masking process is executed, the image capture module  120  captures an image of the document ST and generates raw image data N 1  which is then recorded to the frame memory  130  (Step S 10 ). 
     Once the raw image data N 1  is recorded to the frame memory  130 , the marker detection module  140 , using a known pattern matching process, analyzes whether a masking process marker MK is present in the raw image data N 1  (Step S 12 ). On the basis of the analysis, it is then determined whether a Create Mask marker MKa-MKc was detected as a masking process marker MK (Step S 14 ), and if a Create Mask marker MKa-MKc was not detected, the unmodified raw image data N 1  captured by the image capture module  120  continues to be output by the image output module  170  and the image encoding module  180  (Step S 16 ). 
     If in Step S 14  it is decided that a Create Mask marker MKa-MKc was detected, the marker detection module  140  now determines if an Erase Mask marker MKe was detected in the raw image data N 1  (Step S 18 ). If an Erase Mask marker MKe was not detected, the marker detection module  140  now detects the class of the Create Mask marker that was detected in Step S 14 , as well as the position of the Create Mask marker within the raw image, its size, and inclination (Step S 20 ). If multiple classes of Create Mask markers are detected at this time, position, size, and inclination of each Create Mask marker is detected. 
     Once the class, position, size, and inclination of Create Mask marker is detected in Step S 20 , the mask image generation module  150  then reads the mask range data that corresponds to the class of the detected Create Mask marker, from the mask information INF that was saved to the flash memory  184  (Step S 22 ), and generates a mask image MI (Step S 24 ). At this time, using a known coordinate transformation process (e.g. affine transformation) the mask image generation module  150  adjusts the position, inclination, and size of the mask image MI according to the position, inclination, and size of the Create Mask marker detected in Step S 20 . 
     Once the mask image MI is generated by the mask image generation module  150 , the synthesized image generation module  160  reads the raw image data N 1  from the frame memory  130 . The mask image MI that was generated by the mask image generation module  150  is then synthesized with the raw image data N 1  to generate a synthesized image (Step S 26 ). Once a synthesized image is generated in this way, the synthesized image is then output by the image output module  170  and the image encoding module  180  (Step S 28 ). 
       FIG. 5  is an illustration depicting an example of a synthesized image N 2  displayed on the liquid crystal display  200 .  FIG. 5  shows a display example of the synthesized image N 2  in an instance in which the raw image data N 1  contains two Create Mask markers MKa, MKb. Where two Create Mask markers MKa, MKb are positioned in the raw image data N 1  in this way, respective mask range data sets for the two Create Mask markers MKa, MKb are read from the mask information INF, and a mask image MI is displayed at each single position of the Create Mask markers MKa, MKb. 
       FIG. 6  is an illustration depicting a display example in an instance in which the Create Mask marker is inclined at an angle. Where the Create Mask marker is inclined at an angle θ within the raw image data N 1 , the coordinates of the mask range data are adjusted according to this angle θ. As a result, the position and inclination of the mask image MI within the raw image data N 1  are adjusted as shown in  FIG. 6 . 
       FIG. 7  is a drawing depicting a display method in an instance in which the size of a Create Mask marker detected in raw image data differs from the original size.  FIG. 7  ( a ) depicts the original size of the Create Mask marker, and  FIG. 7  ( b ) depicts an example in which a Create Mask marker enlarged 2× through optical zoom is detected in the raw image data. In instances such as this in which Create Mask marker size different from the original size is detected, the display position and size of the mask image MI are adjusted according to the magnification factor (2× in the case of  FIG. 7 ). 
     If the Create Mask marker is inclined within the raw image data, and if moreover the Create Mask marker is different from its original size, the processes illustrated in  FIG. 6  and  FIG. 7  are performed simultaneously on the mask image MI. 
       FIG. 8  is a drawing depicting a display example in an instance in which an Erase Mask marker MKe is detected in raw image data. In Step S 18  above, if an Erase Mask marker MKe is detected in the raw image data N 1 , an erase signal is output from the marker detection module  140  to the synthesized image generation module  160 . As a result, even if the Create Mask markers MKa, MKb are present in the raw image data N 1  as shown in  FIG. 8 , mask images MI are not synthesized with the raw image data N 1 , m and the unmodified raw image data N 1  is output from the image output module  170  or the image encoding module  180  (Step S 16 ). Thus, if for example the Erase Mask marker MKe is positioned on the document ST subsequent to display of mask images MI thereon, the previously displayed mask images MI are erased, and the content of the document ST is displayed on the liquid crystal display  200 . 
     According to the presentation device  100  of the present embodiment described above, mask images registered beforehand in mask information INF may be synthesized with the raw image data for display, simply by positioning Create Mask markers on the document ST. Thus, the user can easily mask a desired range on the document. Masking ranges are registered in mask information INF that is looked up during generation of mask images MI, in the form of relative coordinates from the position of the Create Mask marker. Thus, even if the document ST shifts, the mask image MI also shifts on the display screen in response to shifting of the document ST. As a result, it is possible for the user to accurately mask the desired section. Additionally, according to the present embodiment, the inclination and size of mask images MI are adjusted according to the inclination and size of the Create Mask markers, so the user is able to accurately mask the desired section regardless of the orientation in which the document ST is captured. 
     In the present embodiment, when an Erase Mask marker is positioned on the document ST, even if a Create Mask marker was previously positioned on the document ST, the mask image MI is erased. Thus, even if for example the document ST has a Create Mask marker printed thereon, it is possible to easily erase the mask image MI. Also, according to the present embodiment, if an Erase Mask marker MKe is detected in the raw image data, the mask image MI is erased regardless of the position, inclination, and size of the Create Mask marker, so it is possible for mask images to be deleted more easily. 
     C. Modifications 
     It is to be understood that while the invention has been shown herein through certain preferred embodiments, there is no intention to limit the invention thereto, and various alternative aspects are possible within the spirit and scope of the invention. Possible modifications include the following, for example. 
     Modification 1 
     In the preceding embodiment, registration of mask range data is carried out using the control console  103  provided to the presentation device  100 . However, registration of mask range data may be carried out by some other method. For example, if the flash memory  184  shown in  FIG. 2  is provided as a detachable memory card, it is possible for mask range data to be edited beforehand by a computer or the like. Alternatively, it is possible for mask range data to be edited directly from a computer connected via the USB interface  195 . 
     Modification 2 
     Registration of mask range data may be accomplished by other methods as well. For example, the user pre-positions a Create Mask marker on the document ST, and then places over the section to be masked paper of prescribed color equal in dimensions to the section to be masked. In this condition, the document ST is captured by the image module  120  of the presentation device, whereupon the marker detection module  140  detects the Create Mask marker and the range of prescribed color mentioned above. Once the Create Mask marker and the range of prescribed color are detected in this way, the mask registration module  182  associates the detected range of prescribed color with the Create Mask marker that was detected at the same time, and records the association in the mask information INF. By registering mask range data by this method, it is possible for the user to easily register mask range data. 
     Modification 3 
     The preceding embodiment showed an example in which a prescribed gap is provided between the Create Mask marker and the mask image MI. However, the mask image MI may instead be displayed adjacently to the Create Mask marker. This makes it easy for the user to specify a position for placement of the mask image MI. In this case, the range that is masked may be established in advance according to the design of the Create Mask marker. Through selective use of the Create Mask markers the user can thus easily specify a range for masking. 
     Modification 4 
     In the preceding embodiment, the Create Mask markers have a design with a letter of the alphabet positioned within a rectangular frame, but Create Mask markers could instead be composed of a barcode or the like. Mask range data would then be recorded in the barcode. With this arrangement, the range for masking can be determined through analysis of the barcode, without having to register mask range data in the flash memory  184 . 
     Modification 5 
     In the preceding embodiment, Create Mask markers and an Erase Mask marker are provided as the masking process markers, but the masking process markers are not limited to these, and markers that enable execution of various other processes relating to mask synthesis may be provided as well. For example, markers that enable display of predetermined still images or video within mask images MI may be provided. Markers for carrying out animation that renders mask images MI progressively lighter in color, or animation that shifts mask images MI to another position or off-screen may be provided as masking process markers. 
     Modification 6 
     In the preceding embodiment, all mask images MI are erased when an Erase Mask marker is detected in the raw image data N 1 . However, alternative arrangements in which, for example, only the mask image MI that is closest to the Erase Mask marker is erased are also possible. Also, where multiple classes of Create Mask markers are provided, corresponding Erase Mask markers may be respectively provided for the Create Mask markers. This makes it possible to easily specify a mask image MI for erasure. 
     Modification 7 
     In the preceding embodiment, the masking process depicted in  FIG. 4  is carried out by ASICs constituting the marker detection module  140 , the mask image generation module  150 , the synthesized image generation module  160 , the image output module  170 , and the image encoding module  180 . However, the masking process may be carried out through software by a microcomputer furnished with a CPU, RAM and ROM. 
     Modification 8 
     In the preceding embodiment, the Create Mask markers have a design with a letter of the alphabet positioned within a rectangular frame. However, this design is arbitrary, and any design enabling detection of position, direction, and size is acceptable. Likewise, any design may be selected appropriately as the design for the Erase Mask marker.