Abstract:
An object follow-up mechanism, installed in a camera, which allows the camera to follow movement of a main object to be photographed. The mechanism includes an image detection device for taking an image into a photographing visual field and for extracting a feature of the image; an image recognition device for recognizing a possible candidate region, on which the main object locates, on a basis of the feature; a display device for displaying the candidate region(s); a main object region selection device for selecting at least one candidate region from the displayed candidate region(s) as a main object region in which the main object is present; and a main object region storing device for storing the feature extracted by the image detection device as a feature standard with respect to the image in the main object region thus selected.

Description:
This application is based on application No. 10-168280 filed in Japan, the contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a camera, and relates to an object tracing mechanism of the camera which makes it possible to follow up an object to be photographed. 
     2. Description of the Related Arts 
     Conventionally, there has been proposed an auto-focusing camera of a type in which its focusing area (focusing region) can be switched. The auto-focusing camera of this type has a following problem. Namely, provided that a right-hand focusing area  2   c,  for example, of three focusing areas  2   a,    2   b,    2   c  is selected and an object (or a subject) M is brought into a focus as shown in FIG.  1 (A), and provided that the object M is moved in the left direction as shown in FIG.  1 (B), it is not possible to bring the object M into the focus unless a photographer switches the focusing area from the right-hand focusing area  2   c  to the left-hand focusing area  2   a.    
     On the other hand, conventionally, there has been proposed a camera of another type in which a focusing area is automatically determined by foreseeing a movement of the object from its change of contrast for example, so as to execute the focusing operation. According to this type of camera, however, in case that a plurality of objects M 1  to M 8 , to be photographed, move as shown in FIG. 2, a photographer cannot voluntarily select a main object (or a main subject), to be photographed, out of the whole objects. Therefore, which object should be followed, or traced, to be focused on, depends upon the camera itself; namely, the photographer cannot select a particular main object to be focused on. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an object of the present invention to provide a camera with an object tracing mechanism which can follow a movement of a main subject, even if the main subject moves. 
     In order to achieve the above object, according to one aspect of the present invention, there is provided a camera comprising: a detector for sensing an image of an object, for extracting a first characteristic of the image, and for outputting data of the first characteristic extracted; a selector for selecting a particular region within a visual field; and a memory for storing the data of the first characteristic, extracted by the detector, of the image which corresponds to the particular region selected by the selector, as characteristic reference data. 
     In the mechanism, the visual field, for example, can be a visual field within a finder of the camera. 
     The camera, for example, may be constructed as follows. 
     That is, the detector may further sense the image of the object, extract a second characteristic of the image, and output data of the second characteristic extracted, after the selector selects the particular region within the visual field, wherein the selector compares the data of the second characteristic with the characteristic reference data which is stored in the memory, so that a region generally coincident between the data of the second characteristic and the characteristic reference data is selected as a renewed particular region within the visual field. 
     According to the mechanism, the particular region which has once been selected by the selector, is renewed into the renewed particular region which is generally coincident mutually between the data of the second characteristic and the characteristic reference data, namely the region generally common both to the data of the second characteristic and to the characteristic reference data, within the visual field. Therefore, the object is followed up, or traced, within the visual field of the camera, when the object moves. 
     In order to achieve the above object, according to another aspect of the present invention, there is provided a camera comprising: a detector for sensing an image of at least one object, for extracting a first characteristic of the image, and for outputting data of the first characteristic extracted; a recognition means for recognizing at least one candidate region on which the image of a main object of the at least one object can locate, on a basis of the data of the first characteristic extracted by the detector; a display part for displaying the at least one candidate region which is recognized by the recognition means; a selection means for selecting one of the at least one candidate region, wherein the image of the main object is in the one thereof; and a memory for storing the data of the first characteristic, extracted by the detector, of the image which corresponds to the one, selected by the selection means, of the at least one candidate region, as characteristic reference data. 
     According to the mechanism, there is provided the memory for storing the data of the first characteristic of the image as characteristic reference data. Therefore, by using the characteristic reference data, the object is possible to be followed up, or traced, within the visual field of the camera when the object moves. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This and other objects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which: 
     FIGS.  1 (A),  1 (B) and  1 (C) are explanatory views of one type of conventional camera, showing a situation in which an object (or a subject) to be photographed moves; 
     FIG. 2 is an explanatory view of another type of conventional camera, showing a situation in which many objects (or subjects) to be photographed are present; 
     FIG. 3 is a front view showing a camera with an object tracing mechanism according to a first embodiment of the present invention; 
     FIG. 4 is a rear view showing the camera of FIG. 3; 
     FIG. 5 is an explanatory view showing a multidirectional switch of the camera of FIG. 3; 
     FIG. 6 is an explanatory view showing a finder (or finder window) of the camera of FIG. 3; 
     FIG. 7 is an explanatory view showing a construction of the camera of FIG. 3; 
     FIGS.  8 (A),  8 (B) and  8 (C) are explanatory views for explaining a scope; 
     FIGS.  9 (A),  9 (B) and  9 (C) are explanatory views for explaining a determination of photographing condition; 
     FIGS.  10 (A),  10 (B) and  10 (C) are explanatory views for explaining the determination thereof; 
     FIGS.  11 (A),  11 (B),  11 (C),  11 (D) and  11 (E) are explanatory views showing the camera with the object tracing mechanism according to a second embodiment of the present invention; 
     FIG. 12 shows a construction of the camera with the object tracing mechanism according to a modification of the embodiment; 
     FIG. 13 shows a construction of the camera with the object tracing mechanism according to another modification of the embodiment; and 
     FIG. 14 shows a construction of the camera with the object tracing mechanism according to still another modification of the embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before a description of the preferred embodiments of the present invention proceeds, it is to be noted that like or corresponding parts are designated by like reference numerals throughout the accompanying drawings. 
     Referring to FIGS. 3 through 14, a detailed description is made below on a camera with an object tracing mechanism according to a first embodiment of the present invention and on the camera with the object tracing mechanism according to a second embodiment thereof. 
     First, referring to FIGS. 3 through 10, the description is made below on the camera with the object tracing mechanism according to the first embodiment thereof. 
     As shown in FIG. 3 which is a front view of the camera with the object tracing mechanism, and as shown in FIG. 4 which is a rear view thereof, the camera with the object tracing mechanism is a single-lens reflex camera which has a camera body  10  and an interchangeable lens  50  mounted thereto. The camera of the first embodiment has a construction generally similar to a construction of a conventional camera in appearance; however, the former camera is different from the latter in a display within a finder window  12 , in a multidirectional switch  20  which is provided on a rear surface of the camera body  10 , and in a selection button  24  which is also provided thereon. 
     That is, as shown in FIGS. 5 and 6, a scope “S” is displayed on the finder window  12 . The scope “S” moves in any direction “a” to “h” in compliance with a push, or press, against a desired location of a peripheral portion  22  of the multidirectional switch  20 . 
     The selection button  24  is positioned at a central portion of the multidirectional switch  20 . As will be described in detail later, when the selection button  24  is pushed or pressed, a characteristic, or a feature, of an image within a region corresponding to the scope “S” is stored, or memorized. 
     Next, referring to FIG. 7, a main internal construction of the camera is described below. 
     The camera body  10  has a control microcomputer  30 , an auxiliary light emitting part  32  connected to the control microcomputer  30 , a light emission controller  34  connected thereto, a photometric module  36  connected thereto, a focus detection module  38  connected thereto, a C-MOS sensor  40  connected thereto, an AF encoder  42  connected thereto, and an AF actuator  44  connected thereto. The control microcomputer  30  includes a CPU and a memory, and the control microcomputer  30  executes a general control over operation of the camera. 
     More specifically, the auxiliary light emitting part  32  emits an auxiliary light which is used for detecting a focus. The light emission controller  34  controls emission of the auxiliary light which is emitted from the auxiliary light emitting part  32 . The photometric module  36  measures a luminance, or brightness, of an object (or a subject) to be photographed. The focus detection module  38  detects a focusing condition of an optical system  54  in an interchangeable lens  50 . The C-MOS sensor  40  is so positioned as to pick up, or sense, an image formation position within a finder window  12  included in a finder optical system, in which the C-MOS sensor  40  takes in an image within a photographing region or area of the camera, processes the image at a high speed, and outputs to the control microcomputer  30  an image information upon a configuration, or outline, of the image and upon its movement (i.e. direction, and amount of movement). The C-MOS sensor  40  is constituted as a single element which is constituted by a MOS type of light receiving cell capable of reading data at a higher speed than a CCD (i.e. charge-coupled device) and by a processing part for extracting a characteristic, or a feature, thereof by processing the data read by the light receiving cell, at a high speed. The control microcomputer  30  processes a small amount of the data after the characteristic, or feature, thereof is extracted; therefore, the control microcomputer  30  is able to execute its control operation at a high speed. 
     The AF encoder  42  detects an amount of operation of the AF actuator  44 . The AF actuator  44  drives a focusing lens in the optical system  54  of the interchangeable lens  50  through a lens drive system of the interchangeable lens  50 . 
     The interchangeable lens  50  has a lens microcomputer  52  in addition to the optical system  54 . The lens microcomputer  52  is connected with the control microcomputer  30  of the camera body  10  so that both the lens microcomputer  52  and the control microcomputer  30  communicate with each other. 
     Next, referring to FIGS.  8 (A),  8 (B),  8 (C), FIGS.  9 (A),  9 (B),  9 (C), and FIGS.  10 (A),  10 (B),  10 (C), it is explained below about an operation of the camera. 
     First, as shown by an arrow in FIG.  8 (A), the multidirectional switch  20  (see FIG. 5) is manipulated to move the scope “S” displayed on the finder window  12 , so that the scope “S” is superimposed, or overlapped, over a desired region (or area) of an object “M” where the desired region is the region that is desired to be followed, or traced, as shown in FIG.  8 (B). 
     Then, the selection switch  24  is pressed. Thereby, the desired region over which the scope “S” is superimposed, is set as a main object region (or a main subject region). At this time, the control microcomputer  30  stores in the memory its image information (or image characteristic), extracted by the C-MOS sensor  40 , upon the main object region, as a reference of the character. 
     Then, after the main object region is set, the control microcomputer  30  compares new image information (or image character), extracted by the C-MOS sensor  40 , upon image in the photographing region, with the reference of the character which has been stored in the memory. 
     Then, when a part, or piece, of the new image information which is generally coincident with the reference of the character is detected, the control microcomputer  30  updates the part, or piece, as the main object region. 
     Then, as shown in FIG.  8 (C), the microcomputer  30  moves the scope “S” to the updated main object region. In this manner, the scope “S” is moved to follow, or trace, the movement of the object “M”. 
     A photographing condition is determined on a basis of the main object region. 
     That is, for example, when the main object region is set by superimposing the scope “S” over the object “M”, focusing areas (or focusing regions)  2   c,    2   b,  and  2   a  over which the scope “S” superimposes following the movement of the object “M” , are selected sequentially as shown in FIGS.  9 (A),  9 (B) and  9 (C), and the object “M” is brought into the focus (or is focused) in each of the focusing areas  2   c,    2   b,  and  2   a.    
     Meanwhile, as shown in FIGS.  10 (A),  10 (B) and  10 (C), photometric cells  4   e,    4   h,    4   j ;  4   e,    4   g,    4   j ; and  4   d,    4   f,    4   i  over which the scope “S” superimposes are sequentially selected from a plurality of photometric cells  4   a  to  4   n  which are included in the photometric module  36  and which are arranged in a shape of honeycomb, in accordance with the movement of the object “M”. An exposure of the camera is determined on a basis of the selected photometric cells  4   e,    4   h,    4   j ;  4   e,    4   g,    4   j ; and  4   d,    4   f,    4   i.    
     Next, referring to FIGS.  11 (A) through  11 (E), the description is made below on the camera with the object tracing mechanism according to the second embodiment. 
     The camera with the object tracing mechanism of the second embodiment is similar to the camera of the first embodiment in construction; however, the former camera is different from the latter in manner of setting the main object region. 
     That is, when there exist a plurality of objects, to be photographed, within a photographing region as shown in FIG.  11 (A), the control microcomputer  30  recognizes outlines of the objects, on a basis of image information (or image characteristic), extracted by the C-MOS sensor  40 , upon the image within the photographing region, as shown in FIG.  11 (B). And, the control microcomputer  30  seeks for the outline(s) of the object(s) which superimpose(s), or overlap(s), any one(s) of six focusing regions  3   a  to  3   f,  as shown in FIG.  11 (C). 
     Then, as shown in FIG.  11 (D), the control microcomputer  30  determines a center position of the outline of each of the object(s) which superimpose(s) any one(s) thereof. And, the control microcomputer  30  makes each of scopes T 0  to T 3 , located at each center position, be displayed on the finder window  12 , respectively. At an initial setting, for example, one scope T 0  which is centrally positioned with respect to the scopes T 0  to T 3 , is so displayed as to be the most conspicuous of all as shown in FIG.  11 (E), in order to indicate that the particular object region which the scope T 0  superimposes, or is positioned on, has been selected as a main object region. Then, similarly to the first embodiment, following the movement of the selected main object, the scope T 0  moves, and a photographing condition is set on basis of the main object region. 
     Similar to the first embodiment, it is possible to switch, or move, the above main object region to the object region which any one of the other scopes T 1  to T 3  superimposes, by operating the multidirectional switch  20  and the selection switch  24 . 
     The camera of the first and second embodiments can follow the movement of the main object when it moves. 
     The present invention is not limited to the aforementioned embodiments and modifications. 
     For example, as shown in FIG. 12, an interchangeable lens  50   a  may accommodate therein a mechanism to control driving the interchangeable lens  50   a ; namely, the interchangeable lens  50   a  may accommodate therein an AF actuator  56  which drives a focusing lens in the optical system  54 , an AF encoder  57  for detecting the driving amount of the AF actuator  56 , a PF encoder  58  for detecting the position of the focus lens, and a termination switch  59  for detecting extremities of movement of the focusing lens. And in the construction, the focus lens of the optical system may be driven by a communication between the lens microcomputer  52  installed in the interchangeable lens  50   a  and the control microcomputer  30  installed in the camera body  10   a.    
     Alternatively, instead of employing the constructions shown in FIGS. 7 and 12, a C-MOS sensor  40   a  may have a function of the photometric module  36  as shown in FIGS. 13 and 14. 
     Although the present invention has been fully described in connection with the preferred embodiments and modifications thereof with reference to the accompanying drawings, it is to be noted that other various changes and modifications are also apparent to those skilled in the art. 
     Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.