Abstract:
Apparatuses and methods related to a display apparatus and a control method thereof, are provided. More particularly, the apparatuses and methods relate to a display apparatus and a control method thereof, in which brightness of an area of a screen is adjusted in consideration of an external light source reflected on the screen.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Korean Patent Application No. 10-2013-0118074, filed on Oct. 2, 2013 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Apparatuses and methods consistent with exemplary embodiments relate to a display apparatus and a control method thereof, and more particularly, to a display apparatus and a control method thereof, in which the brightness of a screen is adjusted in consideration of an external light source reflected on the screen. 
         [0004]    2. Description of the Related Art 
         [0005]    With development of technology, a television (TV), a monitor, a portable terminal and/or other similar display apparatuses now support various functions such as Web surfing, games, photographing of a still image or a moving image, etc. as well as a basic function of displaying an image. In particular, functions such as photographing, video calling, games, etc. are available in a display apparatus with a detachable camera or a built-in camera. 
         [0006]    Besides the foregoing functions, the camera provided in the display apparatus senses ambient light of the display apparatus in order to adjust the brightness of an image displayed on a display. For example, if the ambient light of the display apparatus is bright, the image displayed on the display may be brightened so that a viewer can view a more vivid image. On the other hand, if there is little ambient light, the image displayed on the display may be dimmed so that power consumption of the display apparatus can be reduced to conserve energy. 
         [0007]    However, if a fluorescent lamp, a desk lamp, the sun and/or other external light source are regularly reflected from a screen of the display, that is, if the external light source appears on the screen, an image on the screen may be blurred. In this case, the display apparatus with the foregoing function takes only its ambient brightness into account without considering the light of the external light source reflected from a certain region of the screen of the display in order to adjust the brightness of the entire image displayed on the display. This reflected light appears at the certain region of the screen in accordance with a viewing position of a user, and thus obscures the image displayed at that region, thereby deteriorating visibility. Further, if the intensity of light from the external light source is very strong, a user may be dazzled by the reflected light. To address this problem, a user has to inconveniently and manually adjust the brightness or change the settings of the image displayed on the display. 
       SUMMARY 
       [0008]    One or more exemplary embodiments provide a display apparatus and a control method thereof, in which reflection of an external light source from a screen of a display is taken into account to adjust a setting of an image in a certain region on the screen, thereby improving visibility of a user. 
         [0009]    According to an aspect of an exemplary embodiment, there is provided a display apparatus including: a display which comprises a screen for displaying an image thereon; a camera which captures an image of a region in front of the display; and a controller which determines a reflection region of the screen where a degree of reflecting light of an external light source at a viewing position of a user is greater than or equal to a predetermined value based on the image of the region in front of the display, and controls a brightness of the image in the reflection region of the screen to be greater than a brightness of the image in another region of the screen. 
         [0010]    The controller may be configured to determine the reflection region by measuring a distance between the user and the display based on the image of the region in front of the display. 
         [0011]    The controller may be configured to control a contrast value of the image in the reflection region of the screen to be greater than a contrast value of the image in the other region of the screen. 
         [0012]    The controller may be configured to control an edge enhancement value of the image in the reflection region of the screen to be greater than an edge enhancement value of the image in the other region of the screen. 
         [0013]    The camera may be configured to measure an intensity of light emitted from the external light source, and the controller may be configured to control a brightness of the image in the reflection region of the screen in accordance with the measured intensity of the light. 
         [0014]    The controller may be configured to control a contrast value of the image in the reflection region of the screen to be greater than a contrast value of the image in the other region of the screen if the measured intensity of light is greater than or equal to a predetermined value. 
         [0015]    The controller may be configured to control an edge enhancement value of the image in the reflection region of the screen to be greater than an edge enhancement value of the image in the other region of the screen if the measured intensity of light is greater than or equal to a predetermined value. 
         [0016]    The controller may be configured to control brightness of an entire area of the image of the screen to be greater than a brightness of a setup image if both the user and the external light source are reflected on the image of the region in front of the display. 
         [0017]    According to an aspect of another exemplary embodiment, there is provided a method of controlling a display apparatus comprising: capturing an image of a region in front of a display by using a camera; determining a reflection region of a screen of the display where a degree of reflecting light of an external light source at a viewing position of a user is greater than or equal to a predetermined value based on the image of the region in the front of the display; and controlling a brightness of the image in the reflection region of the screen to be greater than a brightness of the image in another region of the screen. 
         [0018]    The determining the reflection region of the screen may comprise: measuring a distance between the user and the display based on the image of the region in front of the display; and determining the reflection region of the screen based on the measured distance. 
         [0019]    The method may be provided further comprising: controlling a contrast value of the image in the reflection region of the screen to be greater than a contrast value of the image in the other region of the screen. 
         [0020]    The method may be provided further comprising: controlling an edge enhancement value of the image in the reflection region of the screen to be greater than an edge enhancement value of the image in the other region of the screen. 
         [0021]    The method may be provided further comprising: measuring intensity of light emitted from the external light source by using the camera; and controlling a brightness of the image in the reflection region of the screen in accordance with the measured intensity of the light. 
         [0022]    The method may be provided further comprising: controlling a contrast value of the image in the reflection region of the screen to be greater than a contrast value of the image in the other region of the screen if the measured intensity of the light is greater than or equal to a predetermined value. 
         [0023]    The method may be provided further comprising: controlling an edge enhancement value of the image in the reflection region of the screen to be greater than an edge enhancement value of the image in the other region of the screen if the measured intensity of the light is greater than or equal to a predetermined value. 
         [0024]    The method may be provided further comprising: controlling a brightness of an entire area of the image of the screen to be greater than a brightness of a setup image if both the user and the external light source are reflected on the image of the region in front of the display. 
         [0025]    According to an aspect of another exemplary embodiment, there is provided a non-transitory computer readable medium comprising computer executable instructions that cause a computer to perform: capturing an image of an area in front of a display; determining a region of the display where a light reflected by the display at a viewing position of a user is greater than or equal to a predetermined value based on the captured image; and increasing a brightness of the determined region of the display to be greater than a brightness of another region of the display. 
         [0026]    The non-transitory computer readable medium may further include computer executable instructions that cause the computer to perform: measuring a distance between the user and the display using the captured image. The region of the display where the light reflected by the display at the viewing position of the user is greater than or equal to the predetermined value may be determined based on the measured distance. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The above and/or other aspects will become apparent and more readily appreciated from the following description of exemplary embodiments, taken in conjunction with the accompanying drawings, in which: 
           [0028]      FIG. 1  is a block diagram schematically showing a display apparatus according to an exemplary embodiment; 
           [0029]      FIG. 2  illustrates a use state schematically showing a display apparatus according to an exemplary embodiment; 
           [0030]      FIGS. 3 to 6  schematically show methods of determining a reflection region in the display apparatus according to exemplary embodiments; and 
           [0031]      FIGS. 7 and 8  are schematic flowcharts of controlling the display apparatus according to exemplary embodiments. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0032]    Below, a display apparatus and a control method thereof according to exemplary embodiments will be described in detail with reference to accompanying drawings. 
         [0033]      FIG. 1  is a block diagram schematically showing a display apparatus  1  according to an exemplary embodiment; 
         [0034]    As shown in  FIG. 1 , a display apparatus  1  in this exemplary embodiment includes a camera  10  which photographs or captures a moving image/a still image of an external environment, a communicator  20  which transmits and receives data or the like to and from an exterior, an image processor  30  which processes an image signal to display a received image, a display  40  which displays an image, a controller  50  which controls operations of the display apparatus  1 , and a storage  60  which stores predetermined data. 
         [0035]    In this exemplary embodiment, the display apparatus may include any device, which can process an image signal/image data and display it, such as a TV, a monitor for a computer, a portable multimedia player, a mobile phone, etc. to which the camera  10  is detachably connected or internally provided. However, the exemplary embodiments are not limited thereto. 
         [0036]    The camera  10  may be detachably connected to or internally provided in the display apparatus  1 . Further, the camera  10  senses and photographs external environments of the display apparatus  1 . 
         [0037]    The camera  10  may monitor the external environments for a predetermined period of time or at predetermined time intervals, and acquire an image by photographing a front region of the display  40  (hereinafter, referred to as a ‘photographed image’). For example, if it is sensed that a user and an external light source are located in front of the display apparatus  1 , the camera  10  informs the controller  50  that the user and the external light source are sensed, and photographs the sensed user and external light source, thereby transmitting the photographed image to the controller  50 . Also, the camera  10  senses an intensity of light from the external light source and transmits it to the controller  50 . 
         [0038]    The communicator  20  may not only include elements for receiving a signal/data from an external input, but also further include various additional elements such as a wireless communication module (not shown) for wireless communication, a tuner (not shown) for tuning to a broadcasting signal, etc. in accordance with designs of the display apparatus  1 . In addition to receiving a signal from an external device, the communicator  20  may transmit information/data/signals of an image processing apparatus to the external device. That is, the communicator  20  is not limited to receiving a signal from the external device, and may be an interface for interactive communication. Further, the communicator  20  may include a communication module for short range wireless communication such as Bluetooth, infrared (IR), ultra wideband (UWB), Zigbee, etc., and may further include a communication port for wired communication. 
         [0039]    The communicator  20  may transmit image data photographed by the camera  10  to the controller  50 , and send a command signal for controlling the camera  10  from the controller  50  to the camera  10 , if the camera  10  is detachably provided in the display apparatus  1 . 
         [0040]    The image processor  30  processes an image signal, received through the communicator  20 , to be displayed as an image. The image processor  30  may perform demodulation, analog-to-digital (A/D) conversion, decoding, de-multiplexing, etc. in order to extract an image from the image signal. Also, the image processor  30  may perform scaling so that an image can be displayed with a predetermined size on the display  40 ; adjustment of characteristics such as brightness, color, contrast, etc. of an image; and various image enhancement processes for enhancing quality of an image. 
         [0041]    The image processor  30  applies various imaging processes previously set up with regard to a source image which includes a broadcasting signal and an image signal received from an image source (not shown), such as an image signal received from the communicator  20 , an image signal photographed by the camera  10 , and an image signal stored in the storage  60 . The image processor  30  outputs the image signal subjected to such processes to the display  40  so that a processed source image can be displayed on the display  40 . 
         [0042]    The display  40  may display an image based on an image signal output from the image processor  30 . There is no limit to the type of the display  40 . For example, the display may be one of various types of displays such as liquid crystal, plasma, a light-emitting diode, an organic light-emitting diode, a carbon nano-tube, nano-crystal, etc. 
         [0043]    The display  40  may include an additional element in accordance with its type. For example, if the display  40  is achieved by the liquid crystal, the display  40  may include a liquid crystal display panel (not shown), a backlight unit (not shown) emitting light to the display panel, and a panel driving substrate (not shown) for driving the display panel. 
         [0044]    Further, the display  40  displays an image of an external environment photographed by the camera  10 , so that a user can check it. 
         [0045]    The storage  60  is provided as a nonvolatile memory (i.e., writable read only memory (ROM)) such as a flash memory, a hard disk drive, etc., and stores information and a program needed for operating the display apparatus  1 . The information needed for operating the display apparatus  1  may include all the information to be referred to while performing various functions, for example, information display, brightness control for an image, volume control, etc. The display apparatus  1  performs operations by executing a program stored in the storage  60 . Here, the program includes an operating system (OS), an application program, etc. 
         [0046]    The storage  60  stores data about a face size, a distance between eyes, etc. of an average human. This data will be used in calculating an actual distance between the display apparatus  1  and a user by measuring a human&#39;s face size or the like within an image photographed by the camera  10 . 
         [0047]    The controller  50  generally controls the display apparatus  1 . The controller  50  may include a control program, a nonvolatile memory such as a flash memory or the like for storing the control program, a volatile memory such as a random access memory for loading at least a part of the control program, a microprocessor for executing the loaded control program. 
         [0048]    The controller  50  receives a photographed image involving a user and an external light source located in front of the display  40  from the camera  10 ; determines a reflection region from which light of the external light source is reflected with respect to a viewing position of the user within the region of the screen on the display  40 , based on the photographed image; and controls the brightness of the image in the reflection region of the screen to be greater than the brightness of the image in the other region. 
         [0049]      FIG. 2  illustrates a use state schematically showing the display apparatus  1  according to an exemplary embodiment. 
         [0050]    Referring to  FIG. 2 , a user  70  is located at a right side and an external light source  80  is located at a left side in front of the display apparatus  1 . Here, the external light source  80  may be any light source that can emit light, such as a lighting device, the sun, etc. If the display  40  is viewed at the location of the user  70 , the light emitted from the external light source  80  is regularly reflected from the screen of the display  40  and appears in the screen of the display  40 . At this time, the user  70  views an external light source  41  reflected in a reflection region  42  of the screen on the display  40 . Like this, if an image is displayed in the screen on the display  40 , the image in the reflection region where external light is regularly reflected from the screen is more blurred than the image in the other region, thereby deteriorating visibility. 
         [0051]    To solve the foregoing problems, the camera  10  placed in an upper portion of the display apparatus  1  according to an exemplary embodiment photographs the user  70  and the external light source  80  located in front of the display apparatus  1  and transmits the photographed image to the controller  50 . Then, the controller  50  measures a distance between the display  40  and the user  70  based on the photographed image, determines a position of the reflection region  42  where the external light source  80  is reflected in the screen on the display  40  based on the measured distance, and controls the brightness of the reflection region  42  to be greater than the brightness of the other region, thereby preventing the visibility from being deteriorated. 
         [0052]    Below, a method of determining the reflection region  42  from which the external light source  80  is reflected in the screen on the display  40  will be described in more detail. 
         [0053]      FIGS. 3 to 6  schematically show methods of calculating a position of a reflection region S in the display  40  apparatus according to exemplary embodiments. 
         [0054]    First, the user  70  and the external light source  80  located in front of the display apparatus  1  are photographed by the camera  10  provided in the display apparatus  1 . Further, the camera  10  transmits the photographed image  12  to the controller  50 . 
         [0055]    The controller  50  measures a face size, a distance between eyes, etc. of a user within the photographed image  12  and compares them with data about a face size, a distance between eyes, etc. of an average human stored in the storage  60 , thereby calculating a distance d 1  between the display  40  and the user  70 . 
         [0056]    Further, the controller  50  calculates a horizontal distance f and a vertical distance d2 from the user  70  to the external light source  80 , based on the calculated distance d 1  between the display  40  and the user  70 . Here, an incident angle θ i  of incident light emitted from the external light source  80  to the display  40  is equal to a reflective angle θ, of reflecting light reflected from the display  40  to the user  70 . Thus, if the incident angle θ i  is obtained, it is possible to calculate a horizontal distance b between the user  70  and the reflection region S, thereby determining the position of the reflection region S on the display  40 . 
         [0057]    In more detail, referring to  FIG. 3 , d 1 , d 2  and f are constant values because they can be obtained by the controller through the photographed image  12 ; a is obtained from d 2 ·tan θ 1 ; and b is obtained from d 1 ·tan θ o . Here, a+2b is f and θ i  is equal to θ o , and therefore θ i  is tan −1 (f/(2d 1 +d 2 )). Thus, it is possible to obtain θ i  by substituting d 1 , d 2  and f obtained as above. 
         [0058]      FIGS. 4 to 6  are views for determining the reflection region S by calculating a horizontal position and a vertical position of the reflection region S on the display  40  through the foregoing calculating method. 
         [0059]      FIG. 4  shows an example that horizontal positions w L1  and w L2  of the reflection regions due to two external light sources L1 and L2 in the display apparatus  1  are obtained based on the photographed image  12  of the user  70  and the external light sources L1 and L2 located in front of the display apparatus  1 . 
         [0060]    To obtain the horizontal positions w L1  and w L2  of the reflection region, a horizontal direction of the photographed image  12  is arranged to be in parallel with a width direction w of the display apparatus  1 , and a horizontal directional center of the photographed image  12  is aligned with a width directional center of the display apparatus  1 . Further, if the position of the reflection region is calculated through the method shown in  FIG. 3 , at the location of the user  70 , the horizontal position of the reflection region where the first external light source L1 is reflected in the display apparatus  1  is w L1 , and the horizontal position of the reflection region where the second external light source L2 is reflected in the display apparatus  1  is w L2 . 
         [0061]      FIG. 5  shows an example that vertical positions h L1  and h L2  of the reflection regions due to two external light sources L1 and L2 in the display apparatus  1  are obtained based on the photographed image  12  of the user  70  and the external light sources L1 and L2 located in front of the display apparatus  1 . 
         [0062]    To obtain the vertical positions h L1  and h L2  of the reflection region, a vertical direction of the photographed image  12  is arranged to be in parallel with a height direction h of the display apparatus  1 , and a vertical directional center of the photographed image  12  is aligned with a height directional center of the display apparatus  1 . Further, if the position of the reflection region is calculated through the method shown in  FIG. 3 , at the location of the user  70 , the vertical position of the reflection region where the first external light source L1 is reflected in the display apparatus is h L1 , and the vertical position of the reflection region where the second external light source L2 is reflected in the display apparatus  1  is h L2 . 
         [0063]      FIG. 6  shows the reflection region on the display  40 , based on the horizontal position of the reflection region obtained as shown in  FIG. 4  and the vertical position of the reflection region obtained as shown in  FIG. 5 . When the display  40  is viewed at the location of the user  40 , the reflection region where the first external light source L1 is reflected in the display  40  is S L1  where the line w L1  corresponding to the horizontal position intersects the line h L1  corresponding to the vertical position, and the reflection region where the second external light source L2 is reflected in the display  40  is S L2  where the line w L2  corresponding to the horizontal position intersects the line h L2  corresponding to the vertical position. 
         [0064]      FIGS. 7 and 8  are schematic flowcharts of controlling the display apparatus according to exemplary embodiments. 
         [0065]    Referring to  FIG. 7 , a method of controlling the display apparatus  1  according to an exemplary embodiment includes photographing a front of the display  40  through the camera  10  (S 100 ), determining whether a user and external lighting are present in the photographed image (S 110 ), and selecting whether to control the brightness of the entire image to be greater than the brightness of a setup image (S 120 ) if the user and the external lighting are present in the photographed image (YES of S 110 ). If the user selects the brightness of the entire image to be greater than the brightness of the setup image (YES of S 120 ), the controller  50  controls the brightness of the screen on the display  40  to become brighter than the currently setup brightness. On the other hand, if the user selects the brightness of the entire image not to be greater than the brightness of the setup image (No of S 120 ), the controller  50  measures a distance between the display  40  and the user (S 130 ). After the distance between the display  40  and the user is measured (S 130 ), the controller  50  determines the reflection region, from which light emitted from the external light source is regularly reflected in the screen of the display  40 , through the calculation method shown in  FIG. 3  (S 140 ). Further, the controller  50  adjusts the brightness of the image in the reflection region where the external light source is reflected in the screen of the display  40  to be greater than the brightness of the image in the other region (S 150 ), thereby improving visibility. Also, the controller  50  determines whether the photographed image taken by the camera  10  photographing a front of the display  40  involves the user and the external light (S 100 ), and does not control the brightness of the screen on the display  40  if the photographed image does not involve the user and the external light (No of S 110 ). 
         [0066]    Referring to  FIG. 8 , in a method of controlling the display apparatus  1  according to another exemplary embodiment, the camera  10  photographs a front of the display  40  (S 200 ), and the controller  50  measures a distance between a user and the display  40  if the photographed image involves the user and external light (S 210 ). When the distance between the display and the user is measured (S 210 ), the controller  50  determines the reflection region where light emitted from the external light source is regularly reflected from the screen of the display  40 , based on the measured distance through the calculating method shown in  FIG. 3  (S 220 ). Further, the camera measures the intensity of the light emitted from the external light source (S 230 ), and the controller  50  controls the brightness of the image in the reflection region where the external light source is reflected in the screen of the display  40  to be greater than the brightness of the image in the other region (S 250 ) if the measured intensity of the light is less than or equal to a predetermined value (NO of S 240 ). On the other hand, if the measured intensity of the light is greater than or equal to a predetermined value (YES of S 240 ), the controller  50  maximizes the brightness of the image in the reflection region where the external light source is reflected in the screen of the display  40  (S 260 ), and adjusts one of a contrast value and an edge enhancement value of the image in the reflection region (S 270 ). The amount of the brightness adjustment of the image in the reflection region may be adjusted or may vary according to the measured intensity of the light emitted from the external light source. This is to improve visibility by increasing the contract value or the edge enhancement value or by increasing both the contract value and the edge enhancement value when the intensity of the light from the external light source is so strong that the visibility is deteriorated even though the brightness of the image in the reflection region is maximized. 
         [0067]    In the display apparatus and the control method according to an exemplary embodiment, the brightness of an image in a region where an external light source is reflected in a screen of the display is controlled to be greater than the brightness of an image in the other region, thereby having an effect on improving a user&#39;s visibility. 
         [0068]    Further, it is possible to increase the brightness of an image only in a certain region where an external light source is reflected in a screen of the display, thereby having an effect on reducing power consumption in the display apparatus as compared with that of when the brightness of the image of the entire screen region is increased. 
         [0069]    Although a few exemplary embodiments have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles and spirit of the inventive concept, the scope of which is defined in the appended claims and their equivalents.