Patent Publication Number: US-2016234415-A1

Title: Image capturing device and method for image processing

Description:
RELATED APPLICATIONS 
     This application claims priority to China Application Serial Number 201510063341.8, filed Feb. 6, 2015, which is herein incorporated by reference. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an image capturing device and methods for image processing. 
     2. Description of Related Art 
     Surveillance cameras are often used to monitor areas such as banks, casinos, airports, military bases, police stations and convenience stores. Surveillance camera systems can monitor different areas from a central control room. For some places are not suitable for monitoring by people, surveillance cameras can be installed to continuously monitor these places or monitor such areas for some specific conditions. 
     For low-light environment monitoring (e.g., night surveillance), surveillance cameras are typically used with infrared light sources. Because infrared light is invisible to the human eye, such monitoring with surveillance cameras can be performed without interfering the environment. Due to the fact, it is necessary to include cameras and light sources in such surveillance camera systems, the overall system becomes more complex than a usual camera. 
     SUMMARY 
     This disclosure provides an image capturing device to simplify he overall structure of the image capturing device. 
     In one aspect of the disclosure, an image capturing device is provided. The image capturing device includes a case, a lens cover, a light source, an image capturing module, and a controller. The case and the lens cover integrally form an accommodating space. The light source is disposed in the accommodating space. The image capturing module is disposed in the accommodating space and configured to capture an image through the lens cover. The controller is electrically connected to the light source and the image capturing module. The controller obtains a result image by subtracting the brightness distribution of a built-in ghost image from the brightness distribution of the image. 
     In one or more embodiments, the light source is an infrared light source. 
     In another aspect of the disclosure, a method for image processing is provided. The method includes providing lighting by a light source disposed in an accommodating space formed by a case and a lens cover. Next, an image is captured by an image capturing module disposed in the accommodating space through the lens cover. Finally, a result image is obtained by subtracting the brightness distribution of a built-in ghost image from the brightness distribution of the image. 
     In one or more embodiments, the ghost image is obtained by multiplying the brightness distribution of a primitive ghost image by a specific number, and the specific number is determined by the exposure time, the film speed, and the aperture size of the image capturing module when the image capturing module is capturing the image. 
     In one or ore embodiments, the brightness contrast of the result image is increased after the result image is obtained. 
     In another aspect of the disclosure, a method for image processing is provided. The method includes providing an image capturing device is provided, in which a light source and an image capturing module of the image capturing device are disposed in an accommodating space formed by a case and a lens cover. Next, the image capturing device is moved, such that the lens cover faces a scene without reflectivity. Subsequently, the light source is turned on, after which a primitive ghost image is captured by the image capturing module through the lens cover. Finally, the primitive ghost image is saved in the image capturing device. 
     In one or more embodiments, the method further includes orienting the image capturing device to face an object. Next, an image is captured by the image capturing module through the lens cover. Finally, a result image is obtained by subtracting the brightness distribution of the primitive ghost image multiplied by a specific number from the brightness distribution of the image, in which the specific number is determined by the exposure time, the film speed, and the aperture size of the image capturing module when the image capturing module is capturing the image. 
     In one or more embodiments, the primitive ghost image is captured by the image capturing module when the light source is turned on and the lens cover faces a scene without reflectivity. 
     By the method for image processing of this disclosure, the light source and the image capturing module can be disposed in the same accommodating space. Therefore, the overall structure of the image capturing device becomes simple, and the light source can be fully protected by the case. 
     It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows: 
         FIG. 1  is a schematic perspective view of an image capturing device and an object according to one embodiment of this invention; 
         FIG. 2  is a flowchart of a method for image processing according to one embodiment of this invention; 
         FIG. 3A  is a schematic view of an image according to one embodiment of this invention; 
         FIG. 3B  is a schematic view of a ghost image according to one embodiment of this invention; 
         FIG. 3C  is a schematic view of a result image according to one embodiment of this invention; 
         FIG. 4  is a flowchart of another method for image processing according to one embodiment of this invention; and 
         FIG. 5  is a schematic block diagram of a controller according to one embodiment of this invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically depicted in order to simplify the drawings. 
       FIG. 1  is a schematic perspective view of an image capturing device  100  and an object  910  according to one embodiment of this invention. An image capturing device  100  is provided, and the image capturing device  100  can be a surveillance camera. Specifically, the image capturing device  100  can be a night surveillance camera to monitor specific areas at night (or to monitor low-light environments). 
     As shown in  FIG. 1 , the image capturing device  100  includes a case  110 , a lens cover  120 , a light source  130 , an image capturing module  140 , and a controller  150 . The case  110  and the lens cover  120  integrally form an accommodating space  200 . The light source  130  is disposed in the accommodating space  200 . The image capturing module  140  is disposed in the accommodating space  200  and configured to capture an image through the lens cover  120 . The controller  150  is electrically connected to the light source  130  and the image capturing module  140 . The controller  150  obtains a result image by subtracting the brightness distribution of a built-in ghost image from the brightness distribution of the image captured by the image capturing module  140 . 
     In a typical surveillance camera, the image capturing module and the light source are disposed in different accommodating spaces. For example, the image capturing module may be disposed in the accommodating space formed by the case and the lens cover, and the light source may be disposed outside the case. In another example, the image capturing module may be disposed in the accommodating space formed by the case and lens cover, and the light source may be disposed in another accommodating space formed by another case and another lens cover. In contrast to the aforementioned examples, the light source  130  and the image capturing module  140  of the image capturing device  100  of this disclosure are both disposed in the accommodating space  200 . Therefore, the overall structure of the image capturing device  100  becomes simple, and the light source  130  can be fully protected by the case  110 . 
     Specifically, because the light source  130  and the image capturing module  140  are both disposed in the accommodating space  200  instead of in two different accommodating spaces, a more integral and aesthetically pleasing external appearance for the image capturing device  100  is achieved. In addition, because the image capturing device  100  does not need an additional case and lens cover to form another accommodating space, the structure of the image capturing device  100  can be simplified and the material needed for manufacture of the image capturing device  100  is minimized. Therefore, the manufacturing cost of the image capturing device  100  is reduced. 
     The light source  130  can be an infrared light source. People having ordinary skill in the art can make proper modifications to the light source  130  depending on the actual application. 
     The image capturing module  140  can include a lens, a shutter, and a sensor. The detailed structure of the image capturing module  140  will not be described herein. The sensor can be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS). 
     Since the structure of the image capturing device  100  is different from that of typical surveillance cameras, the image capturing device  100  needs to be operated using a special method for image processing. The method for image processing is described below. 
       FIG. 2  is a flowchart of a method for image processing according to one embodiment of this invention. As shown in  FIG. 1  and  FIG. 2 , at operation  410 , lighting is provided by the light source  130  disposed in the accommodating space  200  formed by the case  110  and the lens cover  120 . 
     At operation  420 , an image is captured by the image capturing module  140  disposed in the accommodating space  200  through the lens cover  120 . 
     At operation  430 , a result image is obtained by subtracting the brightness distribution of a built-in ghost image from the brightness distribution of the image captured by the image capturing module  140 . 
     Detailed information of the aforementioned operations is described below. 
       FIG. 3A  is a schematic view of the image  310  captured by the image capturing module  140  according to one embodiment of this invention. As shown in  FIG. 1  and  FIG. 3A , at operation  420 , specifically, the image capturing device  100  is facing an object  910 . Next, the image capturing module  140  captures the image  310  through the lens cover  120 . Because the image capturing device  100  faces the object  910  the image of the object  920  will be in the image  310 . However, because the light source  130  and the image capturing module  140  are both disposed in the accommodating space  200 , part of the light emitted by the light source  130  to the lens cover  120  will be reflected to the light capturing module  140 , and thus at least one ghost  312  is formed in the image  310 . Therefore, some regions in the image  310  are interfered with the ghost  312  and do not seem clear. 
       FIG. 3B  is a schematic view of the ghost image  320  according to one embodiment of this invention. As shown in  FIG. 3B , only the ghost  322  appears in the ghost image  320 , and there are no other images of objects in the ghost image  320 . In other words, the ghost image  320  is a superimposed image of a black image and the ghost  322 . The ghost  322  in the ghost image  320  corresponds to the ghost  312  in the image  310  in  FIG. 3A . 
       FIG. 3C  is a schematic view of the result image  330  according to one embodiment of this invention. As shown in  FIG. 3A  to  FIG. 3C , because the image  310  is interfered with the ghost  312  and becomes unclear, the method of image processing of this disclosure performs operation  430 , which involves obtaining the result image  330  by subtracting the brightness distribution of the built-in ghost image  320  from the brightness distribution of the image  310 . Because the ghost  322  in the ghost image  320  corresponds to the ghost  312  in the image  310 , after the brightness distribution of the ghost image  320  is subtracted from the brightness distribution of the image  310 , the result image  330  with only the image of the object  920  and without the interference of the ghost is obtained. 
     The ghost  322  in the ghost image  320  must correspond to the ghost  312  in the image  310 , such that the result image  330  without the interference of the ghost can be obtained after image processing. Therefore, the ghost image  320  must be generated by a special method, which is described below. 
       FIG. 4  is a flowchart of another method for image processing according to one embodiment of this invention. As shown in Fig,  1  and  FIG. 4 , at operation  510 , the image capturing device  100  in  FIG. 1  is provided, in which the light source  130  and the image capturing module  140  of the image capturing device  100  are both disposed in the accommodating space  200  formed by the case  110  and the lens cover  20 . 
     At operation  520 , the image capturing device  100  is moved, such that the lens cover  120  faces a scene without reflectivity. Specifically, a scene without reflectivity can be the night sky or a black curtain without reflectivity (the lens cover  120  faces the black curtain). 
     At operation  530 , the light source  130  is turned on. Because the lens cover  120  faces a scene without reflectivity at this time, the light emitted by the light source  130  and passing through the lens cover  120  is not reflected back to the image capturing module  140 , and only the light that is reflected by the lens cover  120  and which is also emitted by the light source  130  is emitted back to the image capturing module  140 . 
     At operation  540 , a primitive ghost image is captured by the image capturing module  140  through the lens cover  120 . Related to the aforementioned description, the light reflected back to the image capturing module  140  by the lens cover  120  will form the ghost in the primitive ghost image, and there is no other light to form any other image in the primitive ghost image. Therefore, the primitive ghost image is a superimposed image of a black image and the ghost. 
     At operation  550 , the primitive ghost image is saved in the image capturing device  100  for subsequent image processing. 
     As shown in  FIG. 3A  and  FIG. 4 , the primitive ghost image is captured by the image capturing module  140  when the light source  130  is turned on, and the image  310  is also captured by the image capturing module  140  when the light source  130  is turned on. Therefore, the optical states of the internal space of the image capturing device  100  (or the accommodating space  200 ) when the primitive ghost image is captured and when the image  310  is captured are approximately the same (compared with the optical state of the internal space of the image capturing device  100  when the primitive ghost image is captured, when the image  310  is captured, not only is there the light reflected by the lens cover  120 , but there is also the light reflected from the ambient environment to form the image of the ambient environment such as the image of the object  920 ). Therefore, the ghost in the primitive ghost image corresponds to the ghost  312  in the image  310 . 
     As shown in  FIG. 1 , after the primitive ghost image is generated, the image capturing device  100  can capture the image of the ambient environment such as the object  910  and perform the method for image processing as shown  FIG. 2 . 
     As show in  FIG. 1  and  FIG. 3A  to  FIG. 3C , when the image capturing module  140  is capturing the primitive ghost image and the image  310 , the parameters may not be the same, i.e., the exposure time, the film speed (ISO), and the aperture size of the image capturing module  140  may not be the same when the image capturing module  140  is capturing the primitive ghost image and the image  310 . Therefore, when operation  430  of  FIG. 2  is performed, the ghost image  320  is obtained by multiplying the brightness distribution of the primitive ghost image by a specific number, in which the specific number is determined by the exposure time, the film speed (ISO), and the aperture size of the image capturing module  140  when the image capturing module  140  is capturing the primitive ghost image and the image  310 . Subsequently, the result image  330  is obtained by subtracting the brightness distribution of the ghost image  320  from the brightness distribution of the image  310 . 
     For example, when the image capturing module  140  is capturing the primitive ghost image, the film speed (ISO) is 100, and the exposure time is one-fifteenth of a second. Moreover, when the image capturing module  140  is capturing the image  310 , the film speed (ISO) is 100, and the exposure time is one-thirtieth of a second. Therefore, the ghost image  320  is obtained by multiplying the brightness distribution of the primitive ghost image by two (the image capturing module  140  basically does not change aperture size, so the aperture size is assumed to be a constant). In another example, when the image capturing module  140  is capturing the primitive ghost image, the film speed (ISO) is 100, and the exposure time is one-fifteenth of a second. Moreover, when the image capturing module  140  is capturing the image  310 , the film speed (ISO) is 200, and the exposure time is one-thirtieth of a second. Therefore, the ghost image  320  is obtained by multiplying the brightness distribution of the primitive ghost image by one. 
     Furthermore, when the image capturing module  140  is capturing the primitive ghost image or the image  310 , in addition to the ghost with a specific pattern formed by the light reflected to the image capturing module  140  by the lens cover  120  and emitted from the light source  130 , a flare is also formed, which is evenly distributed in the entire primitive ghost image or the image  310 . Because the ghost image  320  is obtained by multiplying the brightness distribution of the primitive ghost mage by a specific number, the brightness of the flare  324  in the ghost image  320  may not be the same as the brightness of the flare  314  in the image  310 . After the brightness distribution of the ghost image  320  is subtracted from the brightness distribution of the image  310 , the brightness contrast of the result image  330  is usually less than the brightness contrast of the image  310 . Therefore, it is preferred to increase the brightness contrast of the result image  330  by the controller  150  (see  FIG. 1 ) after the result image  330  is obtained, such that the brightness contrasts of the result image  330  and the image  310  can be approximately the same. 
       FIG. 5  is a schematic block diagram of the controller  150  according to one embodiment of this invention. As shown in  FIG. 5 , the controller  150  includes a signal processing module  152 , a memory module  154 , an information transmission/ acquisition module  156 , and power management module  158 . Each of the memory module  154 , the information transmission/ acquisition module  156 , and power management module  158  is electrically connected to the signal processing module  152 . 
     The signal processing module  152  may be a digital signal processor (DSP). People having ordinary skill in the art can make proper modifications to the signal processing module  152  depending on the actual application. 
     The memory module  154  may be a random access memory (RAM), a flash memory, or a memory card. More specifically, the memory card may be a secure digital memory card. 
     The information transmission/ acquisition module  156  may be a wired module, such as a universal serial bus (USB) module, or a wireless module, such as a Bluetooth module or a radio module complying with a Wi-Fi standard. 
     The power management module  158  may be a power management unit. People having ordinary skill in the art can make proper modifications to the power management module  158  depending on the actual application. 
     By selecting different embodiments of the signal processing module  152 , the memory module  154 , the information transmission/ acquisition module  156  and the power management module  158 , the image capturing device  100  can be flexibly applied to different environments. 
     By the method for image processing of this disclosure, the light source  130  and the image capturing module  140  can be disposed in the same accommodating space  200 . Therefore, the overall structure of the image capturing device  100  becomes simple, and the light source  130  can be fully protected by the case  110 . 
     All the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 
     Any element in a claim that does not explicitly state “means for” performing a specified function, or “step for” performing a specific function, is not to be interpreted as a “means” or “step” clause as specified in 35 U.S.C. §112, 6th paragraph. In particular, the use of “step of” in the claims herein is not intended to invoke the provisions of 35 U.S.C. §112, 6th paragraph.