Abstract:
A method and apparatus for preventing image blur due to camera motion, and more particularly, to a method and apparatus for sensing a camera motion, calculating an amount of the camera motion based on the sensed camera motion, and expressing the calculated amount of the camera motion to a user so that the user can prevent image blur. The method includes: sensing the camera motion; calculating an amount of the camera motion based on the sensed camera motion; and expressing the calculated amount of the camera motion.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority of Korean Patent Application No. 10-2005-0010858, filed on Feb. 4, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and apparatus for preventing image blur due to camera motion, and more particularly, to a method and apparatus for sensing camera motion, calculating an amount of the camera motion based on the sensed camera motion, and expressing the calculated amount of the camera motion so that a user can take steps to prevent image blur. 
     2. Description of Related Art 
     When photographing an image using a camera, a motion, such as the tremble or movement of the hand or the body, is transmitted to the camera, and the transmitted motion causes image blur. 
     Generally, there are two types of camera motion. The first type concerns vertically moving on a lens axis of the camera, and the second type concerns horizontally moving on the lens axis of the camera. The first type is a vertical motion referred to as pitching, and the second type is a horizontal motion referred to as yawing. Whenever a user presses a shutter button of the camera to photograph an image, the camera pitches or yaws. 
       FIG. 1  illustrates a camera when a beam of light from an object A to be photographed reaches a surface of a film  20  after passing through a lens  10  of the camera. When no motion is transmitted to the camera as shown in  FIG. 1A , the beam of light from the object A is accurately focused on a point B of the surface of the film  20 . When the camera pitches as shown in  FIG. 1B , the beam of light from the object A is focused on a point B′ of the surface of the film  20 . While a shutter of the camera is open, the beam of light from the object A moves between the points B and B′. 
     Methods and apparatuses for compensating for sensed camera motion or opening a shutter when the amount of the camera motion does not exceed a predetermined threshold value have been studied to photograph images unaffected by even a little camera motion. 
     However, conventional image photographing methods and apparatuses do not feed back the amount of the camera motion to a user. Thus, since the user does not know the amount of the camera motion, the user cannot forcibly close the shutter when the amount of the camera motion exceeds a predetermined threshold value, and prevent images photographed from blurring. 
     BRIEF SUMMARY 
     An aspect of the present invention provides a method of sensing the motion of a camera, calculating an amount of the motion of the camera, and expressing the motion of the camera based on the calculated amount of the motion of the camera. 
     An aspect of the present invention also provides an apparatus for sensing the motion of a camera, calculating an amount of the motion of the camera, and expressing the motion of the camera based on the calculated amount of the motion of the camera. 
     An aspect of the present invention also provides a method of continuously photographing images a predetermined number of times, comparing amounts of the motion of the camera for the photographed images, and displaying the photographed images based on the comparison result. 
     An aspect of the present invention also provides an apparatus for continuously photographing images a predetermined number of times, comparing amounts of the motion of the camera for the photographed images, and displaying the photographed images based on the comparison result. 
     According to an aspect of the present invention, there is provided a method of expressing camera motion. The method includes: sensing the camera motion; calculating an amount of the camera motion based on the sensed camera motion; and expressing the calculated amount of the camera motion. 
     The method may further include opening a shutter when the calculated amount of the camera motion does not exceed a first threshold value and photographing an image. 
     The first threshold value may be set in any one of a default setting mode, a manual setting mode, and an automatic setting mode. 
     The method may further include displaying the images continuously photographed. The displaying of the images may include: comparing the amounts of the camera motion corresponding to the images continuously photographed; and displaying the images continuously photographed in an order of the amount of the camera motion based on the comparison result. 
     According to another aspect of the present invention, there is provided an apparatus for expressing camera motion, including: a motion sensing unit sensing the camera motion; a motion calculation unit calculating an amount of the camera motion based on the sensed camera motion; and a motion expression unit expressing the amount of the camera motion calculated by the motion calculation unit. 
     The apparatus may further include a photographing unit opening a shutter when the amount of the camera motion expressed by the motion expression unit does not exceed a first threshold value and photographing an image. 
     The first threshold value may be automatically set based on at least one of a shutter speed, a focal distance, an angle of view, a motion frequency, an amount of motion, a threshold value of a number of blurred pixels, and a degree of openness of an aperture. 
     The apparatus may further include a continuous photographing control unit controlling the photographing unit to continuously photograph images a predetermined number of times, and the display unit may display the images continuously photographed. 
     The apparatus may further include a comparison unit comparing the amounts of the camera motion corresponding to the images continuously photographed. 
     According to another aspect of the present invention, there is provided a method of displaying images photographed by a camera. The method includes: continuously photograph the images a predetermined number of times; sensing camera motion when the images are continuously photographed and calculating an amount of the camera motion based on the sensed camera motion; comparing the amounts of the camera motion corresponding to the images continuously photographed; and displaying the images based on the comparison result. 
     According to another aspect of the present invention, there is provided an apparatus for displaying images photographed by a camera. The apparatus includes: a continuous photographing control unit controlling a photographing unit to continuously photograph the images a predetermined number of times; a motion sensing unit sensing camera motion when the images are continuously photographed; a motion calculation unit calculating an amount of the camera motion based on the sensed camera motion; a comparison unit comparing the amounts of the camera motion corresponding to the images continuously photographed; and a display unit displaying the images based on the comparison result. 
     Additional and/or other aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following detailed description, taken in conjunction with the accompanying drawings of which: 
         FIGS. 1A-1B  illustrate a camera when a beam of light from an object to be photographed reaches a surface of a film after passing through a lens of the camera; 
         FIG. 2  is a block diagram of an apparatus for expressing camera motion according to an embodiment of the present invention; 
         FIG. 3  is a block diagram of an apparatus for expressing camera motion according to another embodiment of the present invention; 
         FIG. 4  is a block diagram of an apparatus for expressing camera motion according to another embodiment of the present invention; 
         FIG. 5  is a block diagram of an apparatus for displaying an image based on amounts of camera motion when images are continuously photographed according to an embodiment of the present invention; 
         FIG. 6  is a flowchart illustrating a method of expressing camera motion according to an embodiment of the present invention; 
         FIGS. 7A-7C  illustrate a calculated amount of camera motion according to an embodiment of the present invention; 
         FIG. 8  is a flowchart illustrating a method of expressing camera motion according to another embodiment of the present invention; and 
         FIG. 9  is a flowchart illustrating a method of displaying an image based on amounts of camera motion when images are continuously photographed according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
       FIG. 2  is a block diagram of an apparatus for expressing camera motion according to an embodiment of the present invention. Referring to  FIG. 2 , the apparatus includes a motion sensing unit  210 , a motion calculation unit  220 , a motion expression unit  230 , and a photographing unit  240 . 
     The motion sensing unit  210  senses a camera motion and generates an electrical signal corresponding to the sensed camera motion. The motion sensing unit  210  may be an accelerometer, an angular velocity sensor, an angular accelerometer, and an impact sensor for measuring the acceleration, angular velocity, and angular acceleration of the camera. 
     The motion sensing unit  210  may sense the camera motion with respect to one, two, or three axes of a lens of the camera. 
     The motion calculation unit  220  calculates an amount of the camera motion based on the camera motion sensed by the motion sensing unit  210 . Specifically, the motion calculation unit  220  calculates the amount of the camera motion using at least one of a standard deviation, variance, mean, maximum value, minimum value, and norm of a signal indicating the sensed camera motion with respect to at least one of the first through third axes for a predetermined period of time. 
     Then, the motion calculation unit  220  differentiates or integrates the signal indicating the sensed camera motion at least once and calculates the amount of the camera motion using at least one of the standard deviation, variance, mean, maximum value, minimum value, and norm of the differentiated or integrated signal. 
     The motion expression unit  230  expresses the amount of the camera motion calculated by the motion calculation unit  220 . The motion expression unit  230  expresses the amount of the camera motion using at least one of numerical information, diagrams, icons, changes in color, intensity of sound or different types of sound, intensity of vibration, on/off frequency of light, and intensity of light. 
     For example, the motion expression unit  230  may express the amount of the camera motion calculated by the motion calculation unit  220  using numbers or diagrams such as bars. The motion expression unit  230  may include a sound generator (not shown), which increases the intensity or frequency of sound according to the calculated amount of the camera motion. In addition, the motion expression unit  230  may include a light emitter (not shown), which may increase the intensity or frequency of light or change the color of light according to the calculated amount of the camera motion. 
     The motion expression unit  230  may express whether the camera has moved according to whether the calculated amount of the camera motion exceeds a first threshold value. If the calculated amount of the camera motion exceeds the first threshold value and thus it is impossible to take a photograph, the motion expression unit  230  may express this state using a red finger-shaped icon. If the calculated amount of the camera motion does not exceed the first threshold value, the motion expression unit  230  may express this state using a blue finger-shaped icon. 
     In an embodiment of the present invention, the motion expression unit  230  expresses the amount of camera motion to a photographer. In another embodiment of the present invention, the motion expression unit  230  expresses the amount of the camera motion to a subject to be photographed. In another embodiment of the present invention, the motion expression unit  230  expresses the amount of the camera motion to both the photographer and the subject. 
     The photographing unit  240  opens a shutter when the amount of the camera motion does not exceed the first threshold value and photographs an image. Specifically, the photographing unit  240  opens the shutter for a predetermined period of time when the amount of the camera motion does not exceed the first threshold value expressed by the motion expression unit  230  and photographs an image. 
     In an embodiment of the present invention, the first threshold value may be set to a default value (hereinafter referred to as a default setting mode) or may be set manually by a user (hereinafter referred to as a manual setting mode). In another embodiment of the present invention, the first threshold value may be automatically set based on at least one of a shutter speed, focal distance, angle of view, motion frequency, amount of motion, threshold value of the number of blurred pixels, and the degree of openness of an aperture (hereinafter referred to as an automatic setting mode). 
     For example, the greater the focal distance between a lens of the camera and a charge coupled device (CCD), the narrower the angle of view through the lens, the slower the shutter speed, the greater the effects of the camera motion. In addition, in the case of the same amount of camera motion, an image photographed in a dark place is more blurred than when photographed in a bright place. The first threshold value is automatically set to a value in consideration of at least one of a shutter speed, focal distance, angle of view, motion frequency, amount of motion, threshold value of the number of blurred pixels, and the degree of openness of the aperture. 
     The threshold value of the number of blurred pixels may be automatically set to a default value or manually set by the user. In addition, the threshold value of the number of the blurred pixels may be set to a value obtained after calculating an average motion of the camera for a predetermined period of time. For example, the threshold value of the number of the blurred pixels may be set according to an amount of hand trembles of the user for a predetermined period of time. 
     Although the boundary of an actual image is clear, the boundary of the image enlarged on a monitor after being photographed is blurred. It is assumed that the user is satisfied with an image photographed by a 5 mega-pixel camera when 5 or fewer pixels are blurred. In this case, the threshold value of the number of blurred pixels refers to a maximum number of blurred pixels that the user can allow. 
     If the threshold value of the number of the blurred pixels is set low, the first threshold value is also set low. If the threshold value of the number of blurred pixels is set high, the first threshold value is also set high. Therefore, when the user&#39;s hand trembles badly, the user may set the threshold value of the number of blurred pixels high and then take a photograph. 
       FIG. 3  is a block diagram of an apparatus for expressing camera motion according to another embodiment of the present invention. Referring to  FIG. 3 , the apparatus includes a motion sensing unit  310 , a motion calculation unit  320 , a continuous photographing control unit  330 , a photographing unit  340 , and a display unit  350 . The motion sensing unit  310  and the motion calculation unit  320  are respectively identical to the motion sensing unit  210  and the motion calculation unit  220  illustrated in  FIG. 2 , and thus their descriptions will be omitted. 
     The continuous photographing control unit  330  controls the photographing unit  340  to continuously photograph images a predetermined number of times when the amount of the camera motion calculated by the motion calculation unit  320  does not exceed a first threshold value. Specifically, when the amount of the camera motion calculated by the motion calculation unit  320  does not exceed the first threshold value, the continuous photographing control unit  330  activates the photographing unit  340  the predetermined number of times to continuously photograph images and controls the motion calculation unit  320  to provide to the display unit  350  the amount of the camera motion calculated by the motion calculation unit  320  when the images are photographed. 
     The display unit  350  displays the images photographed continuously. The display unit  350  may display the amounts of the camera motion for the images calculated by the motion calculation unit  320 , together with the images photographed continuously. 
       FIG. 4  is a block diagram of an apparatus for expressing camera motion according to another embodiment of the present invention. Referring to  FIG. 4 , the apparatus includes a motion sensing unit  410 , a motion calculation unit  420 , a continuous photographing control unit  430 , a photographing unit  440 , a comparison unit  450 , a selection unit  460 , and a display unit  470 . The motion sensing unit  410 , the motion calculation unit  420 , the continuous photographing control unit  430 , and the photographing unit  440  are respectively identical to the motion sensing unit  310 , the motion calculation unit  320 , the continuous photographing control unit  330  and the photographing unit  340  illustrated in  FIG. 3 , and thus their descriptions will be omitted. 
     The comparison unit  450  compares the amounts of the camera motion for the images continuously photographed under the control of the continuous photographing control unit  430 . Based on the amounts of the camera motion for the images compared by the comparison unit  450 , the selection unit  460  selects an image having the least amount of camera motion. The display unit  470  displays the image selected by the selection unit  460 . 
     In an embodiment of the present invention, the display unit  470  may display the images continuously photographed in order of the amounts of the camera motion for the images compared by the comparison unit  450 . In an embodiment of the present invention, the display unit  470  may display the amounts of the motion of the camera for the images continuously photographed, together with the images, in order of the amounts of the camera motion for the images compared by the comparison unit  450 . 
       FIG. 5  is a block diagram of an apparatus for displaying an image based on amounts of camera motion corresponding to images continuously photographed according to an embodiment of the present invention. Referring to  FIG. 5 , the apparatus includes a continuous photographing control unit  510 , a photographing unit  520 , a motion sensing unit  530 , a motion calculation unit  540 , a comparison unit  550 , a selection unit  560 , and a display unit  570 . 
     When a user command for photographing an image is input via a user interface (not shown), the continuous photographing control unit  510  controls the photographing unit  520  to continuously photograph the image a predetermined number of times. Then, the continuous photographing control unit  510  controls the photographing unit  520  to open the shutter and photograph the image. The user command may be input through a key panel, voice or motion of the user, etc. 
     The motion sensing unit  530  senses the motion of the camera, such as the acceleration, angular velocity, angular acceleration, and impact of the camera, and generates an electrical signal corresponding to the sensed motion of the camera. 
     The comparison unit  550  compares the amount of the camera motion for each image calculated by the motion calculation unit  540 . Based on the comparison result of the comparison unit  550 , the selection unit  560  selects an image having the least amount of camera motion. The selection unit  560  may select a predetermined number of images having the least amount of camera motion, based on the comparison result of the comparison unit  550 . The display unit  570  displays the image selected by the selection unit  560 . 
     The display unit  570  may display the images continuously photographed in order of the amounts of the motion of the camera for the images compared by the comparison unit  550 . The display unit  570  may display the amounts of the motion of the camera for the images continuously photographed, together with the images, in order of the amounts of the motion of the camera for the images compared by the comparison unit  550 , which is within the scope of the present invention. 
       FIG. 6  is a flowchart illustrating a method of expressing camera motion according to an embodiment of the present invention. Referring to  FIG. 6 , the camera motion is sensed and an electrical signal corresponding to the sensed camera motion is generated (operation  610 ). The camera motion may be the acceleration, angular velocity, and angular acceleration of the camera. 
     The camera motion with respect to one, two, or three axes of a lens of the camera may be sensed. 
     Based on the sensed camera motion, the amount of the camera motion is calculated (operation  620 ). The amount of the camera motion is calculated using at least one of a standard deviation, variance, mean, maximum value, minimum value, and norm of a signal indicating the sensed camera motion with respect to at least one of the first through third axes for a predetermined period of time. 
     The signal indicating the sensed camera motion is differentiated or integrated at least once, and the amount of the camera motion is calculated using at least one of the standard deviation, variance, mean, maximum value, minimum value, and norm of the differentiated or integrated signal. 
     The calculated amount of the camera motion is expressed (operation  630 ).  FIGS. 7A-7C  illustrate the calculated amount of the camera motion according to an embodiment of the present invention. Specifically,  FIG. 7A  shows the calculated amount of the camera motion illustrated using a bar according to an embodiment of the present invention. A portion C of the bar indicates a motion amount corresponding to the first threshold value required to photograph a clear image, and a portion D of the bar indicates the amount of camera motion in the present embodiment. 
       FIG. 7B  illustrates the calculated amount of the camera motion expressed using a bar and a number according to an embodiment of the present invention.  FIG. 7C  illustrates an amount E of camera motion using a circular graph according to an embodiment of the present invention. 
     When the amount of the camera motion does not exceed the first threshold value, the shutter is opened and an image is photographed (operation  640 ). Specifically, when the amount of the camera motion does not exceed the first threshold value, the shutter is opened for a predetermined period of time and an image can be photographed. The first threshold value is automatically set based on at least one of a shutter speed, focal distance, angle of view, motion frequency, amount of motion, and threshold value of the number of blurred pixels. 
       FIG. 8  is a flowchart illustrating a method of expressing camera motion according to another embodiment of the present invention. Referring to  FIG. 8 , the camera motion is sensed (operation  810 ) and the amount of the camera motion is calculated based on the sensed camera motion (operation  820 ). The calculated amount of the camera motion is displayed on a display unit (not shown) (operation  830 ). If the amount of the camera motion displayed on the display unit does not exceed a first threshold value, images are continuously photographed a predetermined number of times (operation  840 ). The amounts of the camera motion for the images continuously photographed are compared (operation  850 ), and an image having the least amount of camera motion is selected based on the comparison result (operation  860 ). The selected image is then displayed (operation  870 ). 
     The images continuously photographed may be displayed in order of the amounts of the camera motion based on the comparison result. The amounts of the camera motion for the images continuously photographed may be displayed together with the images photographed in order of the amounts of the camera motion based on the comparison result. 
       FIG. 9  is a flowchart illustrating a method of displaying an image based on the amounts of camera motion corresponding to images continuously photographed according to an embodiment of the present invention. Referring to  FIG. 9 , when a user command for photographing an image is input, the image is continuously photographed a predetermined number of times (operation  910 ). 
     The camera motion, such as the acceleration, angular velocity, angular acceleration, and impact of the camera, is sensed and the amount of the camera motion is calculated based on the sensed camera motion (operation  920 ). 
     The calculated amounts of the camera motion corresponding to the images are compared (operation  930 ), and an image having the least amount of camera motion is selected based on the comparison result (operation  940 ). A predetermined number of images having the least amount of camera motion may be selected based on the comparison result. The selected image is displayed (operation  950 ). 
     The images continuously photographed may be displayed in order of the amounts of the camera motion corresponding to the images based on the comparison result. The amounts of the camera motion corresponding to the images continuously photographed may be displayed together with the images photographed in order of the amounts of the camera motion based on the comparison result. 
     As described above, according to a method and apparatus for expressing camera motion according to the present invention, an amount of the camera motion is expressed so that a user can recognize the amount of the camera motion. When the amount of the camera motion does not exceed a predetermined first threshold value, a shutter is opened and an image can be photographed. In this case, the amount of the camera motion is expressed so that the user can estimate the time when the amount of the camera motion does not exceed the first threshold value. 
     Embodiments of the present invention can also be implemented as computer-readable code on a computer-readable recording medium. The computer-readable recording medium is any data storage device that can store data which can be thereafter read by a computer system. Examples of the computer-readable recording medium include magnetic storage mediums (such as read-only memory (ROM), floppy disks, and hard disks), optical reading mediums (such as CD-ROMs and DVDs), and carrier waves (such as data transmission through the Internet). 
     Although a few embodiments of the present invention have been shown and described, the present invention is not limited to the described embodiments. Instead, it would be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.