Abstract:
A control device for an image input apparatus which is equipped with an optical system having a magnification varying lens, includes a monitor for displaying input images, an input device which enables an arbitrary position on a display screen of the monitor to be designated, a calculation device for calculating the distance between a predetermined position on the display screen and the arbitrary position on the basis of zooming information of the optical system, and a controller for controlling the image input apparatus in accordance with the calculation results obtained by the calculation device.

Description:
This is a continuation application under 37 CFR 1.62 of prior application Ser. No. 08/278,750, filed Jul. 22, 1994, abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a control device for an image input apparatus and, more specifically, to a control device which is suitable for remotely operating a camera as in the case of a video conference system. 
     2. Description of the Related Art 
     With the improvement of computers in terms of image processing capability, there have been proposed various techniques in which camera operations, such as zooming, panning and tilting, are performed by operating a computer while the photographic image is being displayed on a monitor screen of the computer. In particular, in a video conference system, it is desirable that the orientation (pan, tilt), magnification, etc., of the camera at the other end of the communications line be remotely controllable. For that purpose, there has been proposed, for example, a system in which camera operation factors, which are to be controlled by using a mouse or the like, are displayed on a part of the monitor screen. 
     However, in the above system, it is rather difficult to perform fine adjustment. Moreover, it is by no means easy to determine which factor is to be controlled, and to what degree, so that the operator has to depend on trial-and-error methods. When a camera is to be remotely controlled as in the case of a video conference system, the time lag involved in transmitting the control signal must also be taken into account. In addition, the image is subjected to high-efficiency coding before being transmitted. Thus, the image quality is generally rather poor when the image information changes fast as in the case of panning, thereby making the camera operation still more difficult. In other words, a fine adjustment is impossible. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an image-input-apparatus control device improved in operability. 
     In accordance with an embodiment of the present invention, there is provided a control device for an image input apparatus which is equipped with an optical system having a magnification varying lens, the control device comprising display means for displaying input images, input means which enables an arbitrary position on a display screen of the display means to be designated; calculation means for calculating the distance between a predetermined position on the display screen and the arbitrary position on the basis of zooming information of the optical system, and control means for controlling the image input apparatus in accordance with calculation results obtained by the calculation means. 
     Other objects and features of the present invention will become apparent from the following detailed description of the invention and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic block diagram showing an embodiment of the present invention; 
     FIG. 2 is a schematic diagram of the embodiment connected to a communications network; 
     FIG. 3 is a flowchart illustrating a first operation of this embodiment; 
     FIG. 4 is a diagram illustrating how distances as displayed on a monitor screen are related to the corresponding angles of view; 
     FIG. 5 is a flowchart illustrating a second operation of this embodiments; 
     FIG. 6 is a flowchart illustrating a third operation of this embodiment; and 
     FIG. 7 is a flowchart illustrating a fourth operation of this embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment of the present invention will now be described with reference to the drawings. 
     FIG. 1 is a schematic block diagram showing an embodiment of the present invention as applied to a terminal in a video conference system. Numeral  10  indicates a camera for photographing a user of the system; numeral  12  indicates a photographing zoom lens unit; numeral  14  indicates a zoom control circuit for moving a zooming lens  12   a  of the lens unit  12  in the direction of the optical axis; numeral  16  indicates a focus control circuit for moving a focusing lens  12   b  of the lens unit  12  in the direction of the optical axis; numeral  20  indicates an image sensor which converts optical images obtained by the lens unit  12  and an aperture  18  to electric signals; and numeral  22  indicates a camera signal processing circuit for converting the electric signals obtained by the image sensor  20  to video signals. 
     Numeral  24  indicates a pan control circuit which is on a pan head  23  and which moves the photographic optical axis of the camera  10  to the right and left; numeral  26  indicates a tilt control circuit which is on the panhead  23  and which moves the photographic optical axis of the camera  10  up and down; and numeral  28  indicates a camera control circuit for controlling the camera  10  as a whole. 
     Numeral  30  indicates a computer constructed in the same way as ordinary computers; numeral  32  indicates a CPU for overall control; numeral  34  indicates a ROM; numeral  36  indicates a RAM; numeral  38  indicates a video interface to which output video signals from the camera  10  are input; and numeral  40  indicates a communications interface which transmits and receives data and control signals to and from an external communications network and transmits and receives control signals to and from the camera  10 . 
     Numeral  42  indicates a coordinate input device consisting of a digitizer, a mouse or the like; numeral  44  indicates an interface for the coordinate input device  42 ; numeral  46  indicates a video memory (VRAM); and numeral  48  indicates a display control device for controlling the image display of a monitor  50  consisting of a CRT, a liquid crystal display or the like. 
     As shown in FIG. 2, a number of terminals as shown in FIG. 1 are connected to each other through the intermediation of a communications network. 
     Next, the operation of this embodiment will be described with reference to FIGS. 1 and 3. This embodiment functions in a particularly effective manner when applied to a case where it is used to remotely control a camera at an image transmission end terminal from an image reception end terminal in a video conference which is being executed between terminals. However, for convenience of description, the operation of this embodiment will be explained with reference to a case where the camera  10  is operated within the system shown in FIG.  1 . The features of this embodiment as utilized in the above two cases are the same except for the fact that the processes of image coding and decoding are omitted in the latter case. 
     A photographic image obtained by the camera  10  is written to the memory  46  through the video interface  38 . The display control circuit  48  successively reads image data stored in the video memory  46 , whereby the monitor  50  is controlled to display the image. 
     The user designates an arbitrary position (x, y), which he or she intends to be the center, through the coordinate input device  42  (S 1 ). The CPU  32  calculates the disparity (ΔX, ΔY) between the designated position (x, y) and the coordinates (a, b) of the center of the photographic image displayed on the screen (when no window display system is adopted, it is the center of the screen of the monitor  50  and, when a window display system is adopted, it is the center of the display window of the photographic image) (S 2 ). That is, the CPU  32  calculates the following values: 
     
       
         Δ X=x−a   
       
     
     
       
         Δ Y=y−b   
       
     
     Then, the CPU  32  transfers a movement command, e.g., a command Mov (ΔX, ΔY), to effect movement through a distance corresponding to the disparity (ΔX, ΔY) to the camera control circuit  28  of the camera  10  through the communications interface  40  (S 3 ). 
     Upon receiving this movement command (S 4 ), the camera control circuit  28  first obtains zooming position information of the zooming lens  12   a  from the zoom control circuit  14  (S 5 ), and determines the conversion factor k of the amount of movement from the zooming position information thus obtained (S 6 ). That is, the photographic image is displayed in a size corresponding to the variable magnification of the lens unit  12 . For example, as shown in FIG. 4, distances which appear the same when displayed on the screen of the monitor  50  are different from each other in the actual field depending upon the magnification, i.e., the angle of view. In view of this, it is necessary to convert a distance on the monitor screen to an amount of movement corresponding to the angle of view (the pan angle and the tilt angle). For this purpose, the camera control circuit  28  is equipped with a conversion table for determining the conversion factor k. 
     The determined conversion factor k is multiplied by the parameters ΔX and ΔY of the movement command Mov (ΔX, ΔY) from the computer  30  to calculate the actual amount of movement (ΔXr, ΔYr) (S 7 ). That is, the following values are calculated: 
     
       
         Δ Xr=kΔX   
       
     
     
       
         Δ Yr=kΔY   
       
     
     The camera control circuit  28  determines the pan and tilt angles of rotation in accordance with the actual amount of movement (ΔXr, ΔYr) (S 8 ) to control the pan control circuit  24  and the tilt control circuit  26 , thereby pointing the photographic optical axis of the camera  10  in the designated direction (S 9 ). 
     While in FIG. 3 the camera control circuit  28  of the camera  10  calculates an amount of movement of the camera  10  with respect to the amount of movement as designated on the monitor screen, it is naturally also possible for this calculation to be performed by the CPU  32  of the computer  30 . FIG. 5 shows a flowchart for the latter case which differs from the above-described case in that the zooming position information of the zooming lens  12   a  is transferred from the camera  10  to the computer  30 , which calculates the pan and tilt angles of movement and transfers them to the camera  10 . 
     That is, the user designates an arbitrary position (x, y), which he or she intends to be the center of the photographic image displayed on the monitor  50 , by using the coordinate input device  42  (S 11 ). The CPU  32  calculates the disparity (ΔX, ΔY) between the designated position (x, y) and the coordinates (a, b) of the center of the photographic image as displayed on the screen (when no window display system is adopted, it is the center of the screen of the monitor  50  and, when a window display system is adopted, it is the center of the display window of the photographic image) (S 12 ). Then, the CPU  32  requires the camera  10  to provide zooming position information (S 13 ). 
     Upon the request of zooming position information from the computer  30 , the camera control circuit  28  of the camera  10  obtains zooming position information from the zoom control circuit  14  (S 14 ), and transfers it to the computer  30  (S 15 ). 
     The CPU  32  determines the conversion factor k from the zooming position information from the camera  10  (S 16 , S 17 ). In this example, the CPU  32  is equipped with a conversion factor table for converting a distance on the screen of the monitor  50  to an amount of movement corresponding to the angles of view (the pan and tilt angles), and determines the conversion factor k. 
     The CPU  32  multiplies the determined conversion factor k by the previously calculated ΔX and ΔY to calculate the actual amount of movement (ΔXr, ΔYr) (S 18 ), and determines the pan and tilt angles of rotation corresponding to the calculated actual amount of movement (ΔXr, ΔYr), transmitting a movement command of that angle of rotation to the camera  10  (S 20 ). 
     The camera control circuit  28  of the camera  10  receives the movement command from the computer  30  (S 21 ), and controls the pan control circuit  24  and the tilt control circuit  26  in accordance with the command to point the photographic optical axis of the camera  10  in the designated direction (S 22 ). 
     Next, a case in which a photographic range is designated by two points on the screen of the monitor  50  will be described with reference to FIG.  6 . The user designates two points (x 1 , y 1 ) and (x 2 , y 2 ) in the photographic image plane, which is displayed on the monitor  50 , by the coordinate input device  42  (S 31 ). The CPU  32  calculates a middle point (x 0 , y 0 ) thereof from the designated two points (x 1 , y 1 ) and (x 2 , y 2 ) (S 32 ). The CPU 32  calculates the difference (ΔX, ΔY) between the middle point (x 0 , y 0 ) and the coordinates (a, b) of the center of the photographic-image displaying portion of the monitor  50  (when no window display system is adopted, it is the center of the entire screen of the monitor  50 , and when a window display system is adopted, it is the center of the photographic image display window) (S 33 ). That is, the CPU  32  calculates the following values: 
      Δ X=x   0 − a   
     
       
         Δ Y=y   0 − b   
       
     
     Further, the CPU calculates the difference (Δx, Δy) between the two designated points, that is, the following values (S 34 ): 
     
       
         Δ x=x   1 − x   2   
       
     
     
       
         Δ y=y   1 − y   2   
       
     
     The CPU  32  transfers a movement command in which the differences (ΔX, ΔY) and (Δx, Δy) are used as parameters to the camera  10  (S 35 ). The camera control circuit  28  of the camera  10  receives this command thus transferred (S 36 ), and obtains zooming position information of the zooming lens  12   a  from the zoom control circuit  14  (S 37 ), determining the conversion factor k of the pan and tilt amounts of movement from the zooming position information thus obtained (S 38 ). 
     The camera control circuit  28  multiplies the determined conversion factor k by the parameters ΔX and ΔY of the movement command from the computer  30  to calculate the actual amount of movement (ΔXr, ΔYr), that is, the following values (S 39 ): 
     
       
         Δ Xr=kΔX   
       
     
     
       
         Δ Yr=kΔY   
       
     
     Further, the camera control circuit  28  calculates the amount of movement to a desired zooming position, Δz, from the parameters Δx and Δy from the computer  30  and the factor k (S 40 ). 
     The camera control circuit  28  calculates the actual amounts of movement corresponding to the actual amount of movement (ΔXr, ΔYr) calculated in step S 39 , and calculates the amount of zooming movement corresponding to the amount of movement Az calculated in step S 40  (S 41 ). It then controls the pan control circuit  24 , the tilt control circuit  26  and the zoom control circuit  14 , pointing the photographic optical axis of the camera  10  in the designated direction and changing the magnification of the lens unit  12  (S 42 ). 
     The above-described embodiment is not effective when the user wishes to observe ranges other than that displayed on the monitor screen. In such a case, the user has to move the zooming lens  12   a  of the camera  10  to wide-angle end through another operation, and then perform the above operation. These procedures could be simplified by the following procedures. The CPU sets imaginary screens above and below, and on the right and left-hand sides, of the display screen displaying an image that is being photographed. These imaginary screens may be adjacent to, or partly overlap, or spaced apart from, the actual display screen. FIG. 7 shows the flowchart of an operation utilizing such imaginary screens. 
     The user selects one of the imaginary screens by the coordinate input device  42  or the like (S 51 ). The CPU  32  calculates the disparity between the center (a 1 , b 1 ) of the selected imaginary screen and the coordinates (a, b) of the center of the displayed photographic image (when no window display system is adopted, it is the center of the screen of the monitor  50  and, when a window display system is adopted, it is the center of the display window of the photographic image), that is, the CPU calculates the following values (S 52 ): 
     
       
         Δ X=a   1 − a   
       
     
     
       
         Δ Y=b   1 − b   
       
     
     Then, the CPU  32  transfers a movement command corresponding to the difference (ΔX, ΔY), e.g., Mov (ΔX, ΔY), to the camera control circuit  28  of the camera  10  through the communications interface  40  (S 53 ). 
     The camera control circuit  28 , which receives this movement command (S 54 ), first obtains the zooming position information of the zooming lens  12   a  from the zoom control circuit  14  (S 55 ), and then determines the conversion factor k of the amount of movement from the obtained zooming position information, as in the above described case (S 56 ). 
     The camera control circuit  28  multiplies the determined conversion factor k by the parameters ΔX and ΔY of the movement command Mov (ΔX, ΔY) to calculate the actual amount of movement (ΔXr, ΔYr) (S 57 ). That is, 
     
       
         Δ Xr=kΔX   
       
     
     
       
         Δ Yr=kΔY   
       
     
     Further, the camera control circuit  28  determines the pan and tilt angles of rotation corresponding to the actual amount of movement (ΔXr, ΔYr), (S 58 ), and controls the pan control circuit  24  and the tilt control circuit  26  to point the photographic optical axis of the camera  10  in the designated direction. 
     As stated above, the present invention is obviously also applicable to a case where a camera at an image-transmission-end terminal is to be remotely controlled from an image-reception-end terminal in a video conference or the like. 
     As can be readily understood from the above description, in accordance with this embodiment, a visual and intuitive camera operation can be realized, thereby attaining an improvement in operability. In particular, this embodiment proves markedly effective in cases where remote control is to be performed. 
     While the above embodiment has been described as applied to optical zooming, which is effected by moving a zooming lens, it is also applicable to electronic zooming, in which captured image data is electronically processed.