Abstract:
An endoscope is provided having an imaging sensor, a focusing lens, and an image processor. The imaging sensor converts an optical image to an output image signal. The focusing lens focuses on an object. The image processor calculates a contrast value based on the image signal while the focusing lens moves to focus on an object, and in the case where the image processor detects a region in which the amount of variation in the contrast value is within a predetermined range, while the focusing lens moves in a close range around a focusing point the image processor processes at least one output image in which either the image has been cropped to exclude the region, an ornament has been added to the region, or the region has been softened.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an imager that captures an image and processes the captured image. 
     2. Description of the Related Art 
     Japanese Unexamined Patent Application Publication No. H05-95501 discloses an imager that indicates a warning when an unwanted object, i.e. a finger, is in the angle of view. In such construction, however, an object may move while a user moves a finger out of the angle of view or changes the composition of the picture. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an imager that reduces the influence of an unwanted object in a photograph and releases a shutter at the right moment. 
     An endoscope is provided having an imaging sensor, a focusing lens, and an image processor. The imaging sensor converts an optical image to an output image signal. The focusing lens focuses on an object. The image processor calculates a contrast value based on the image signal while the focusing lens moves to focus on an object, and in the case where the image processor detects a region in which the amount of variation in the contrast value is within a predetermined range, while the focusing lens moves in a close range around a focusing point the image processor processes at least one output image in which either the image has been cropped to exclude the region, an ornament has been added to the region, or the region has been softened. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and advantages of the present invention will be better understood from the following description, with references to the accompanying drawings in which: 
         FIG. 1  is a schematic view of an imager according to the present embodiment; 
         FIG. 2  shows a display that displays a through image in which an unwanted object exists; 
         FIG. 3  shows a display that displays a still image that has been cropped to exclude the region in which an unwanted object exists; 
         FIG. 4  is a flowchart of a cropping process; 
         FIG. 5  shows an AF search region and an unwanted object search region; and 
         FIG. 6  shows another pattern of an AF search region and an unwanted object search region. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is described below with references to the embodiments shown in the drawings. An imager  10  according to the embodiment shown in  FIG. 1  comprises an imaging sensor  11 , a focusing lens  12 , an image processor  13 , a release button  14 , a display  15 , a storage medium  16 , and a controller  17 . 
     Light reflected from an object strikes the imaging sensor  11  after passing through the focusing lens  12 , so that the imaging sensor  11  captures an optical image and converts it to an electric image signal. The image processor  13  creates image data by processing the image signal. The image data is then sent to the display  15 . The display  15  displays an image based on the image data. In the case the digital camera carries out such procedures for only one frame, the display  15  displays a through image. This is called as live view. The controller  17  controls each part of the digital camera  10 , i.e., the image processor. 
     When the release button  14  is depressed halfway, the image processor  13  brings an object into focus by controlling the focusing lens  12 , and calculates exposure conditions, e.g. aperture value, exposure time, etc., based on a brightness signal included in the image signal. While the focusing lens  12  is focused on an object, the image processor  13  directs the movement of the focusing lens  12  along its axis while calculating contrast values based on the brightness signal from a predetermined period. Then, when the image processor  13  determines that an object is in focus of the focusing lens  12  and the contrast value is at its maximum, the focusing lens  12  is fixed in its current position that is focused on an object. 
     The focusing lens  12  can focus on an object at close range from the digital camera  10 , and the range in which the focusing lens  12  moves to bring the object into focus is the close focusing range. While the focusing lens  12  moves in the close focusing range, the image processor  13  determines whether or not a region exists that has a contrast value with a variation that is within a predetermined range. In other words, the image processor  13  detects whether or not a region exists in which the amount of variation in its contrast value is less than or equal to a predetermined range. The detected region, which contains an unwanted object, is described hereinafter. 
     A plurality of virtual AF search regions is provided on a captured image, as shown in  FIG. 5 . The image processor  13  detects the contrast values of all of these AF search regions. That is, the image processor  13  determines whether or not any of the AF search regions have a contrast value that varies within a predetermined range. 
     The image processor  13  detects the hue of the unwanted object region based on its contrast value and determines whether the detected hue is a predetermined hue. The predetermined hue is, for example, a flesh color or a color in the range of black to brown. 
     In the case that the hue of the unwanted object region is a flesh color, the image processor  13  determines that an unwanted object is in the angle of view of the focusing lens  12 . For example, when a finger of a user is in front of the focusing lens  12 , a finger captured in an image creates an unwanted object region because a finger is flesh-colored. In a captured image, a region in which an unwanted object exists is an unwanted object region. In the case that the hue of the unwanted object region is a color in the range from black to brown, the image processor  13  determines that an unwanted object is in the angle of view of the focusing lens  12 . For example, when the back of a person&#39;s head is in front of the focusing lens  12 , a head captured in an image creates an unwanted object region because the back of a head has a color in the range from black to brown. 
     In the case that the image processor  13  determines that a finger is in front of the focusing lens  12 , the close focusing range is a relatively short distance away from the digital camera  10  that is measured in centimeters. In the case that the image processor  13  determines that the back of a person&#39;s head is in front of the focusing lens  12 , the close focusing range is a relatively short distance away from the digital camera  10  that is measured in meters. 
     When the release button  14  is fully depressed, the focusing lens  12  remains focused on an object while the imaging sensor  11  captures an image under the calculated exposure conditions. Then, the image processor  13  creates image data by processing the image signal, and a still image based on the image data is displayed on the display  15 . The image file including the image data is stored in the storage medium. 
     In the case that the image processor  13  determines that a finger of a user or the back of a head is in front of the focusing lens  12 , the operation mode of the digital camera  10  is set to a cropping mode. In the cropping mode, the image processor  13  crops an image to exclude the unwanted object region from the captured image, displays the cropped image on the display  15  (refer to  FIG. 3 ), and stores the cropped image in the storage medium  16 . For example, the unwanted object region is the hatched region shown in  FIG. 2 , and the cropped region is the upper right section of the captured image that is framed by dashed lines. Note that the image processor  13  may crop the center of a captured image so as to exclude the unwanted object region. This cropping method corresponds to a zoom-up technique. 
     The unwanted object region and the hue is determined after the release button  14  is depressed halfway but before it is depressed completely. Image cropping can be carried out only after an image has been captured. 
     The cropping process is described with reference to  FIG. 4 . When the digital camera is powered on, the controller  17  determines whether or not the release button  14  is depressed halfway in Step S 11 . In the case that the release button  14  is not depressed halfway, Step S 11  is repeated. Otherwise, the process continues to Step S 12 . 
     In Step S 12 , the image processor  13  calculates exposure conditions and directs the focusing lens  12  to focus on an object. While the focusing lens  12  is focused on an object, the image processor  13  directs the movement of the focusing lens  12  along its axis and calculates a contrast value based on the brightness signal for a predetermined period so that a hue can be determined based on the calculated contrast value. 
     In Step S 13 , while the focusing lens  12  moves in the close focusing range, the image processor  13  determines whether or not an unwanted object region with a contrast value that varies within a predetermined range exists. In the case that the unwanted object region exists, the process continues on to Step S 14 . Otherwise, the process jumps to Step S 16 . 
     In Step S 14 , the image processor  13  detects the hue of the unwanted object region based on the contrast value and determines whether the detected hue is a predetermined hue, such as a flesh color or a color in the range from black to brown, for example. In the case that the hue of the unwanted object region is a predetermined hue, the process continues on to Step S 15 . Otherwise, the process proceeds to Step S 16 . 
     In Step S 15 , the image process  13  sets the operation mode of the digital camera  10  to the cropping mode. In Step S 16 , the image process  13  sets the operation mode of the digital camera  10  to the normal mode that is different from the cropping mode. 
     In Step S 17 , the camera controller  17  determines whether or not the release button  14  is depressed completely. In the case that the release button  14  is not depressed completely, Step S 17  is repeated. Otherwise, the process continues on to Step S 18 . 
     In Step S 18 , while the focusing lens  12  is focused on an object the imaging sensor  11  captures an image under the calculated exposure conditions. Then, image data is created when the processor  13  processes the image signal, and a still image based on the image data is displayed on the screen  15 . The image file including the image data is stored in the storage medium. In the case that the operation mode of the digital camera  10  is set to a cropping mode, the image processor  13  crops an image to exclude an unwanted object region from the captured image, displays the cropped image on the display  15  (refer to  FIG. 3 ), and stores the cropped image in the storage medium  16 . 
     Therefore, a still image excluding the unwanted object region is created. Note that, as a substitute for cropping, the image processor  13  may add an ornament to the unwanted object region in the process of creating a still image. The ornament may be, for example, the symbol of a heart. According to this construction, a still image is created in which a user cannot recognize the unwanted object region. As another substitute for cropping, the image processor  13  may soften an unwanted object region in the process of creating a still image. 
     Cropping, adding an ornament, and softening are all processes that are carried out after an image has been captured, so that the elapsed time between the moment when the release button is depressed completely and the moment of capture does not increase. Therefore, the digital camera  10  reduces the influence of an unwanted object in a photograph and releases the shutter at the right moment. Note that only one process of cropping, adding an ornament, or softening may be carried out, but two or more of these processes may also be executed for the same image. 
     Virtual AF search regions and unwanted object search regions may be simultaneously indicated on a captured image, as shown in  FIG. 6 . The image processor  13  detects the focusing point of the focusing lens  12  based on the AF search region at the center of a captured image, because the focusing point is detected at or near the center of an image. The image processor  13  detects contrast values for each of the unwanted object search regions that are provided on the periphery of a captured image, because an unwanted object is detected at or near a periphery of a captured image. The unwanted object search regions are indicated differently from the AF search regions so that an unwanted object can be rapidly detected in a short amount of time. 
     Steps S 12  to S 16  may be carried out repeatedly during each period, e.g. every millisecond until the release button  14  is completely depressed, and then the appropriate operation mode of the camera  10  may be set. In the embodiment described hereinbefore, when an unwanted object disappears from the angle of view during the period between Step S 15  and S 17 , the operation mode of the digital camera  10  does not change to the normal mode. On the other hand, when an unwanted object appears in the angle of view between Steps S 16  and S 17  the operation mode of the digital camera  10  is not changed to the cropping mode. Repeating Step S 12  to S 16  effectively resolves such problems. 
     Although the embodiment of the present invention has been described herein with references to the accompanying drawings, obviously many modifications and changes may be made by those skilled in the art without departing from the scope of the invention. 
     The present disclosure relates to subject matter contained in Japanese Patent Application No. 2009-224147 (filed on Sep. 29, 2009), which is expressly incorporated herein, by reference, in its entirety.