Patent Publication Number: US-10334697-B2

Title: Method and device for displaying illumination

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 USC 119(a) of Korean Patent Application No. 10-2015-0139766, filed on Oct. 5, 2015 in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes. 
     BACKGROUND 
     1. Field 
     The following description relates to a device and method for displaying an illumination. 
     2. Description of Related Art 
     As a result of development in mobile graphic processing unit (GPU) technology, a content provider may provide virtual environment content by utilizing three-dimensional (3D) graphics technology of a mobile device. 
     In addition, the 3D graphics technology of the mobile device may generate a virtual object to maximize realism and immersion in an augmented reality (AR) and a virtual reality (VR), thereby providing a user with the virtual object. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     The disclosure relates to a device and method for displaying an illumination. For example, the illumination may be a visual representation, in a vurtual space, of light projected from a light source. For example, the device and method may be applicable to displaying an illumination in 3D graphics technology, and, more particularly, to displaying an illumination in augmented reality (AR) and virtual reality (VR) applications. The device and method may enable an illumination effect to be visualized and displayed with minimum overhead. In one general aspect, a method of displaying an illumination includes: based on illumination information, determining, using a least one processor, an illumination area to which an illumination assigned in a virtual space is projected; and visualizing, using the at least one processor, an illumination effect produced by the illumination with respect to a determined boundary area in the illumination area, the determined boundary area including a boundary and a portion of the determined illumination area that is less than all of the determined illumination area. 
     The determining of the illumination area may include: based on the illumination information, determining, as the illumination area, a space between coordinates of an origin of the illumination and coordinates of nodes that define a base surface of the illumination. 
     The determining of the illumination area may include: based on the illumination information, determining, as the illumination area, an area between two nodes that define a base line of the illumination area and coordinates of an origin of the illumination on a layer corresponding to a viewpoint with respect to the virtual space. 
     The determining of the illumination area may include: determining the illumination area based on at least one of a position, a threshold angle, a direction, an intensity, or a color included in the illumination information. 
     The visualizing may include increasing a brightness of a pixel in the boundary area compared to a brightness of a pixel outside the boundary area in the illumination area. 
     The visualizing may include determining incremental levels of brightness for pixels in the boundary area, based on respective distances between the pixels and an origin of the illumination, and respective distances between the pixels and the boundary. 
     The visualizing may include fitting, to the illumination area, a brightness adjustment map to define incremental levels of brightness for pixels in the boundary area in a predetermined form. 
     The visualizing may include extending the boundary area in response to an overlap between the boundary area and another boundary area of another illumination. 
     The visualizing may include: in response to an overlap between the boundary area and another boundary area of another illumination, visualizing a brightness and a color of the boundary area by overlapping a brightness and a color of the another boundary area in an overlapping area of the boundary area and the another boundary area. 
     The visualizing may include: in response to an overlap between the boundary area and another boundary area of another illumination, assigning a weight to respective incremented levels of brightness for pixels in an overlapping area of the boundary area and the another boundary area. 
     A non-transitory computer readable medium may include programmed instructions configured to control a processor to perform the method of displaying the light source. 
     In another general aspect, a device for displaying an illumination includes: a processor configured to determine, based on illumination information, an illumination area to which an illumination assigned in a virtual space is projected, and define a boundary area comprising a boundary and a portion of the determined illumination area that is less than all of the illumination area; and a display configured to display an illumination effect produced by the illumination with respect to the boundary area. 
     The processor may be further configured to determine, as the illumination area, a space between coordinates of an origin of the illumination and coordinates of nodes that define a base surface of the illumination, based on the illumination information. 
     The processor may be further configured to determine, as the illumination area, an area between two nodes that define a base line of the illumination and coordinates of an origin of the illumination on a layer corresponding to a viewpoint with respect to the virtual space, based on the illumination information. 
     The processor may be further configured to increase a brightness of a pixel in the boundary area compared to a brightness of a pixel outside the boundary area in the illumination area. 
     The processor may be further configured to determine incremental levels of brightness for pixels in the boundary area based on respective distances between the pixels and an origin of the illumination, and respective distances between the pixels and the boundary. 
     The processor may be further configured to fit, to the illumination area, a brightness adjustment map to define incremental levels of brightness for pixels in the boundary area in a predetermined form. 
     The processor may be further configured to extend the boundary area in response to an overlap between the boundary area and another boundary area of another illumination. 
     The processor may be further configured to control the display to display a brightness and a color of the boundary area by overlapping a brightness and a color of another boundary area of another illumination in an overlapping area of the boundary and the another boundary area, in response to an overlap between the boundary area and the another boundary area. 
     The processor may be further configured to assign a weight to respective incremented levels of brightness for pixels in an overlapping area of the boundary area and another boundary area of another illumination, in response to an overlap between the boundary area and the another boundary area. 
     In another general aspect, a method of displaying an illumination includes: determining, using a processor, a first illumination area corresponding to light projected by a first light source, a second illumination area corresponding to light projected by a second light source, a first boundary area of the first light source, wherein the first boundary area includes a first boundary and a portion of the first illumination area that is less than all of the first illumination area, a second boundary area of the second light source, wherein the second boundary area includes a second boundary and a portion of the second illumination area that is less than all of the second illumination area, and an extended boundary area based on an overlap area in which the first boundary area and the second boundary area overlap; and visualizing, using the processor, an illumination effect produced by the first and second light sources with respect to the first boundary area, the second boundary area and the extended boundary area. 
     The visualizing may include: increasing brightness for a pixel in the first boundary area compared to a brightness adjustment for a pixel in a remainder of the first illumination area; and increasing brightness for a pixel in the second boundary area compared to a brightness adjustment for a pixel in remainder of the second illumination area. 
     The visualizing may further include adding, in the overlap area, a brightness adjustment for a pixel in the first boundary area and a brightness adjustment for a pixel the second boundary area. 
     The visualizing may include overlapping, in the overlap area, a color of the first boundary area and a color of the second boundary area. 
     Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flowchart illustrating an example of a method of displaying an illumination. 
         FIG. 2  is a flowchart illustrating another example of a method of displaying an illumination. 
         FIG. 3  illustrates an example of a process of determining an illumination area. 
         FIG. 4  is a flowchart illustrating yet another example of a method of displaying an illumination. 
         FIGS. 5 and 6  illustrate other examples of processes of determining an illumination area. 
         FIGS. 7 through 11  illustrate examples of visualizing a boundary area. 
         FIGS. 12 through 15  are block diagrams illustrating examples of a device for displaying an illumination. 
     
    
    
     Throughout the drawings and the detailed description, unless otherwise described or provided, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience. 
     DETAILED DESCRIPTION 
     The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent to one of ordinary skill in the art. The sequences of operations described herein are merely examples, and are not limited to those set forth herein, but may be changed as will be apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Also, descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted for increased clarity and conciseness. 
     The features described herein may be embodied in different forms, and are not to be construed as being limited to the examples described herein. Rather, the examples described herein have been provided so that this disclosure will be thorough and complete, and will convey the full scope of the disclosure to one of ordinary skill in the art. 
     The terminology used herein is for the purpose of describing particular examples only and is not to be limiting of the examples. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “include/comprise” and/or “have” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and/or groups thereof. 
     Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which examples belong. It will be further understood that terms, such as those defined in commonly-used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     When describing examples with reference to the accompanying drawings, like reference numerals refer to like constituent elements and a repeated description related thereto will be omitted. When it is determined detailed descriptions related to a related known function or configuration may make the purpose of the examples unnecessarily ambiguous, such detailed descriptions will be omitted here. 
       FIG. 1  is a flowchart illustrating an example of a method of displaying an illumination. 
     Referring to  FIG. 1 , in operation S 110 , a processor of a device for displaying an illumination determines an illumination area to which a light or illumination produced by a light source assigned in a virtual space is projected based on illumination information. Although the illumination or light source assigned and used in the virtual space is described as a spotlight, the light source assigned in the virtual space is not limited thereto. 
     The illumination information may include information on a position, a threshold angle, a direction, an intensity, and a color of the illumination in the virtual space. The position of the light source may be referenced using two-dimensional (2D) coordinates or three-dimensional (3D) coordinates of the light source in the virtual space. The direction of the illumination may denote a progress direction of a light projected from the light source, such as from a spotlight. The threshold angle may denote an angle defining a range in which the light projected from the spotlight is represented in the virtual space. The intensity may denote an intensity of the light projected from the light source. The color may denote a color of the illumination. 
     The illumination area may be referred to as a 2D area or a 3D area in which the light produced by the light source is projected in the virtual space. In an example, the processor determines the illumination area based on at least one of the position, the threshold angle, the direction, the intensity, or the color of the illumination included in the illumination information. For example, the processor may determine the illumination area based on the position of the light source by limiting an area to which a light is projected by the light source in the direction of the illumination to the threshold angle. Detailed descriptions of how the illumination area may be determined will be provided with reference to  FIGS. 3, 5, and 6 . 
     In operation S 120 , the processor controls a display to visualize an illumination effect by the illumination with respect to a boundary area including a boundary and a portion of the determined illumination area. The boundary area may be referred to as an area in which the illumination effect produced by the illumination is visualized in the virtual space. The boundary of the illumination area may be an outline excluding a base line or a base surface of the illumination area, and the boundary of the illumination area may be determined based on the position, the direction, and the threshold angle of the illumination. 
     The illumination effect denotes a visual representation of the light projected from the light source. Detailed descriptions of the illumination effect will be provided with reference to  FIGS. 7 through 10 . 
     A method of displaying an illumination may represent a spotlight by minimally covering a background and a target object in a virtual space, so that the method of displaying the illumination can be applied to an application in which a predetermined target object is desired to be highlighted. 
     For example, the method of displaying the illumination may minimally cover an object by centrally representing a boundary portion of a path of a light projected by a light source, and represent an effect of blurring overlapping areas of illumination so that an overlapping portion of paths of lights produced by different light sources are realistically represented. The processor that performs the method of  FIG. 1  may visualize a path of the spotlight in real time by minimally covering or applying illumination to the object, and the visualized path may represent a background without changing or obscuring the background since a sense of incompatibility is reduced even when the background is relatively bright by minimizing such obscuring or illumination application to portions of the illumination path, as only examples. 
       FIG. 2  is a flowchart illustrating another example of a method of displaying an illumination. 
     Referring to  FIG. 2 , in operation S 210 , the processor receives the illumination information. In an example, the processor receives an input of the illumination information from the user through an input receiver. In another example, the processor receives the illumination information from an outside source through wired and wireless communication by a communicator. However, the illumination information is not limited to the aforementioned examples, and may be preset by the processor. 
     In operation S 220 , the processor three-dimensionally defines the illumination area based on the illumination information. For example, the processor determines, as the illumination area, a space between coordinates of the illumination and coordinates of nodes to define a base surface by the light projected from the light source based on the illumination information in the virtual space. The three-dimensionally defined illumination area will be described with reference to  FIG. 3 . 
     In operation S 230 , the processor visualizes a boundary area in the illumination area based on viewpoint information. For example, the processor may project the three-dimensionally defined illumination area to a layer corresponding to a viewpoint based on the viewpoint information on a viewpoint represented on the display at the device for displaying the illumination, and determine a portion and a boundary of the projected illumination area as a boundary area. The boundary area will be described with reference to  FIG. 3 . Examples of methods of visualizing the boundary area will be described with reference to  FIGS. 7 through 11 . 
     The viewpoint information may be information associated with a viewpoint of a predetermined scene. The processor projects the boundary area and the illumination area to the layer corresponding to the viewpoint. The processor may define an increment level of a brightness required in each pixel in the boundary area projected to the corresponding layer, overlay the layer with a scene corresponding to the viewpoint, and increase a brightness of each pixel to represent a scene by the defined increment level. 
       FIG. 3  illustrates an example of a process of determining an illumination area, according to an embodiment. 
     As illustrated in  FIG. 3 , a processor of a device for displaying the illumination, for example, may determine an illumination area  320  produced by a light source  310  in a virtual space as described in operation  220  of  FIG. 2 . For example, the processor may determine the illumination area  320  based on coordinates, a direction, and a threshold angle of the light source  310  in the virtual space. The processor may calculate coordinates of nodes  321  to define a base surface by a light projected from the light source  310  based on the coordinates, the direction, and the threshold angle of the light source  310 . The base surface may be referred to as a bottom or destination at which the light projected from the light source  310  reaches. For example, the processor may define the illumination area  320  in a form of a circular cone, so that an illumination effect may be visualized with a minimum overhead in a mobile environment. The processor may visualize the illumination effect at high speed by simplifying the illumination area  320  in the form of the circular cone. In this example, the processor defines an illumination area using illumination light source and a number of nodes to define a base surface having a circular form in a form of a circular cone. 
     To visualize a boundary area  340  in operation  230  of  FIG. 2 , the processor may determine the boundary area  340  including a portion of the illumination area  320  and a boundary of the illumination area  320 . The boundary area  340  includes an area corresponding to an outline of the illumination area  320 . The processor may determine an incrementing level of a brightness in a pixel in the boundary area  340  based on a distance between this pixel and the light source  310  and a distance between the pixel  329  and the boundary. The incrementing level of the brightness of the pixel  329  indicates a level of which the brightness increases in a pixel representing a scene, in response to a layer  300  corresponding to a viewpoint overlaid on the scene. 
     In an example, in response to the pixel  329  being relatively close to the boundary of the illumination area  320  and the light source  310 , the processor may determine an incremented level of the brightness for that pixel to have a value relatively close to a maximum brightness set based on an intensity of the illumination  310 . In another example, the processor may determine the incremented level of the brightness of a pixel that is in the boundary area  340  but relatively distant from the boundary of the illumination area  320  and the light source  310  to have a decreased value in comparison to the incremented level of brightness of a pixel that is relatively close to the boundary of the illumination area  320  and the light source  310 . Thus, the boundary of the illumination area  320  by the light source  310  may be represented with a maximum brightness, and a pixel that is relatively distant from the boundary of the illumination area  320  and the illumination  310  may be represented with minimized brightness change, or as relatively dark with respect to illumination from the light source  310 . A scattering effect of a light is inversely represented, so that the processor may minimize a cover of an object by a visualization of a path of the light and a user may recognize the illumination area  320  as the path of the light. Thus, the user may recognize a corresponding boundary area as the path of the light due to a similarity in a style of which a brightness gradually changes. 
     In this example, the processor projects the boundary area  340  to the layer  300  corresponding to a viewpoint to visualize the boundary area  340 . A viewpoint  390  may denote a point from which a scene represented on a display of a device is observed. The layer  300  corresponding to the viewpoint  390  may denote a layer to which the illumination area  320  is projected in the virtual space to be seen at the predetermined viewpoint  390 . The processor visualizes the illumination effect with respect to the boundary area  340  by overlaying the layer  300  on the scene to be seen at the viewpoint  390 . 
     In an example, as illustrated in  FIG. 3 , the processor determines an illumination area  330  projected to the layer  300  corresponding to the viewpoint  390  and a boundary area  350  projected to the layer  300  based on viewpoint information. For example, as described above, the processor determines the incremented level of the brightness in the projected boundary area  350  by projecting, to the layer  300 , the increment level of the brightness determined based on the distance between the example pixel  329  and the light source  310  and the distance between the example pixel  329  and the boundary in the boundary area  340 . However, the processor may make additional determinations. For example, the processor may determine the incremented level of the brightness in a pixel  339  on the layer  300  based on a position with respect to the boundary, a position of the light source  310 , and the position of the pixel  339  on the layer  300  with respect to the pixel  339  in the boundary area  350  projected to the layer  300  corresponding to the viewpoint  390 . 
     According to one or more embodiments, the processor overlays, on a scene corresponding to the viewpoint  390 , the layer  300  indicating the incremental levels of the brightness in pixels in the projected boundary area  350 . For example, the processor may visualize the illumination effect in the boundary area  340  by increasing a brightness of the pixel  329  corresponding to a scene by the corresponding incremented level of the brightness in the pixel  339  of the layer  300  overlaid on the scene. The processor may change colors of pixels of a scene to which the boundary area  340  is overlaid by reflecting a color of the light source  310  in response to the light source  310  having the color. 
     In an example, in response to the illumination area  320  being defined as a circular cone, the processor may calculate a distance from a predetermined pixel to an illumination, a distance from the pixel to a boundary, and a brightness value in the pixel to determine the extent that the illumination from the light source  310  is represented in the scene. 
       FIG. 4  is a flowchart illustrating an example of still another example of a method of displaying an illumination. 
     In operation S 410 , the processor receives illumination information. The processor may receive the illumination information in a way similar to that of operation S 210  illustrated in  FIG. 2 . 
     In operation S 420 , the processor two-dimensionally defines an illumination area based on illumination information and viewpoint information. For example, differently from the process illustrated in  FIG. 2 , the processor may define the illumination area as a 2D area on a layer corresponding to a viewpoint. Based on the illumination area, the processor may determine, as the illumination area, an area between two nodes to define a base line of the 2D area by a light projected from the light source, and may determine coordinates of the light source on a layer corresponding to the viewpoint with respect to a virtual space. In an example, based on the viewpoint information and the illumination information, the processor may use a predefined function to calculate coordinates of two nodes to define the base line by the light projected from the light source, and to define the coordinates of the light source. The two-dimensionally defined illumination area is described in more detail with reference to  FIGS. 5 and 6 . 
     In operation S 430 , the processor visualizes a boundary area in the illumination area. For example, the processor may determine, as the boundary area, an area including a portion of the illumination area and a boundary of the defined illumination area. Detailed descriptions of the boundary area are provided below with reference to  FIGS. 5 and 6 . Example visualizations of the boundary area are described below with reference to  FIGS. 7 through 11 . 
       FIGS. 5 and 6  illustrate other examples of a process of determining an illumination area. 
       FIG. 5  illustrates an example of an illumination area  520  and a boundary area  540  represented on a layer  500  corresponding to a viewpoint. The processor may determine the illumination area  520  produced by illumination light source  510  in a virtual space, as described above in operation S 420  of  FIG. 4 . In an example, the processor may calculate coordinates, for example, (x 1 , y 1 , z 1 ) illustrated in  FIG. 5 , of the illumination  510  on the layer  500  corresponding to the viewpoint based on illumination information and viewpoint information. The processor may further calculate coordinates, for example, (x 2 , y 2 , z 2 ) and (x 3 , y 3 , z 3 ) illustrated in  FIG. 5 , of each of nodes  521  and  522  to define a base line by a light projected from the light source  510  on the layer  500  corresponding to the viewpoint, based on the illumination information and the viewpoint information. The base line may be referred to as a bottom of the layer  500  corresponding to the viewpoint, and the light projected from the light source  510  reaches the bottom. The processor may determine, as the illumination area  520 , an area between a position of the light source  510  and positions of the two nodes  521  and  522  to define the base line. For example, the processor may determine the illumination area  520  in a form of a triangle based on 3D coordinates of nodes or vertices of the triangle, so that an illumination effect may be visualized with a minimum computational or memory overhead in a mobile environment. The processor may visualize the illumination effect at high speed by simplifying the calculating of the illumination area  520  in the form of the triangle. In this example, to define an illumination area, the processor may manage three nodes including two nodes to define a base surface and a node corresponding to an illumination. 
     As described in operation S 430  of  FIG. 4 , the processor may determine the boundary area  540  including a portion of the illumination area  520  and a boundary of the illumination area  520  to visualize the boundary area  540 . The boundary area  540  includes an area corresponding to an outline or contour of the illumination area  520 . The processor may determine an incremented level of a brightness for a pixel in the boundary area  540  based on a distance between the pixel and the light source  510  and a distance between the pixel and the boundary. For example, the processor may determine the incremented level of the brightness in this pixel to be inversely proportional to the distance between the pixel and the light source  510 , and the distance between the pixel and the boundary of the illumination area  520 . The processor may determine the incremented level of the brightness for respective pixels to be a relatively large values in response to the pixels being relatively close to the light source  510  and/or the boundary of the illumination area  520 . As examples, the processor may determine the incremented level of the brightness of the example pixel  529  to be a relatively small value or zero in response to the pixel  529  being relatively distant from the light source  510  and the boundary of the illumination area  520 , such as shown in  FIG. 5 . 
     To visualize the boundary area  540 , the processor may overlay, to a scene corresponding to the viewpoint, the layer  500  corresponding to the viewpoint and including the boundary area  540  in which incremented levels of the brightness have been determined for pixels of the boundary area  540  and optionally additional pixels in other areas of the illumination area  520  beyond the boundary area  540 . For example, the processor may visualize an illumination effect in the boundary area  540  by increasing a brightness of pixels corresponding to the scene by the incremented levels of brightness for the pixels of the layer  500  overlaid to the scene. The processor may change a color of a pixel of a scene corresponding to the boundary area  540  by reflecting a color of the light source  510 . The effects of the color of the light source  510  may also be incrementally represented. 
     In an example, the processor may calculate a distance from a predetermined pixel to an illumination, a distance from the pixel to a boundary, and a brightness value in the pixel in response to the illumination area  520  being defined as a triangle. 
       FIG. 6  illustrates an example of an illumination area  620  and a boundary area  640  represented on a layer  600  corresponding to a viewpoint. In an example, a memory of a device for displaying an illumination may store a brightness adjustment map to define incremented levels of brightness of pixels in the boundary area  640  in a predetermined form. For example, a form of the brightness adjustment map may be identical to a form of the boundary area  640  and may be a triangular form with respect to an light source  610  of a spotlight type. For example, the brightness adjustment map may define an incremented level having a relatively small value in response to a pixel being relatively distant from the light source  610  and a boundary of the illumination area. The brightness adjustment map may define the incremented level of the brightness with respect to pixels of the boundary area  640 , while maintaining a preset or existing brightness with respect to remaining areas, e.g., without incremented brightness. For example, the processor may visualize an illumination effect with a minimum overhead using the brightness adjustment map defined in a form of a triangle. In this example, the processor may manage three nodes including two nodes corresponding to a base line and a node corresponding to an illumination. The processor may visualize the illumination effect at high speed based on the brightness adjustment map having a simplified form. 
     To visualize the boundary area  640  as described above in operation  430  of  FIG. 4 , the processor may fit, to the illumination area  620 , e.g., defined by the nodes of the triangle, the brightness adjustment map to define the incremented levels of brightness in pixels in the boundary area  640  in a predetermined form. For example, based on the illumination information, the processor may match a node corresponding to the light source  610  in the brightness adjustment map to a position of the illumination on the layer  600  corresponding to the viewpoint. The processor may match two nodes corresponding to a base line of the brightness adjustment map to coordinates of the nodes  621  and  622  corresponding to a base line of the illumination area  620 , respectively. Thus, the brightness adjustment map may be stretched, reduced, or otherwise changed based on a size and a form of the illumination area  620 . 
     In an example, the memory may pre-store the brightness adjustment map to define the incremented levels of brightness for the pixels in the boundary area  640 , so that the device for displaying the illumination may not calculate the increment level of the brightness based on a pixel, an illumination, and a distance between boundaries. Thus, an amount of operations performed by the processor may be reduced when rendering the scene, according to one or more embodiments. In response to the reduced amount of operations, an amount of time and power required for displaying the illumination may be reduced in the device for displaying the illumination. 
     Since the memory stores the brightness adjustment map in advance instead of calculating distance between a pixel and the illumination and between the pixel and a boundary, the processor may perform a low-overhead loading operation of the brightness adjustment map, thereby largely reducing the amount of operations to be performed on each pixel. 
       FIGS. 7 through 11  illustrate examples of visualizing a boundary area. 
       FIG. 7  illustrates visualization of a boundary area  740  in a case in which a single light source  710  is provided in a virtual space. The processor may determine an illumination area and the boundary area  740 , which includes a boundary of an illumination area  720  and a portion of the illumination area  720 , such as discussed above with regard to in  FIGS. 1 through 6 . Although  FIG. 7  only illustrates the light source  710  in the virtual space for ease of description,  FIG. 7  is merely a non-limiting example. For example, a background and an object may exist in the virtual space, in addition to the illumination represented as originating from the light source  710 . 
     The processor may visualize, through a display  700 , an illumination effect with respect to a scene based on a viewpoint in response to incremented levels of brightness for pixels in the boundary area  740 . For example, the processor may increase (with respect to a remainder of the illumination area  720 ) the brightness of the pixel in the boundary area  740  of the scene corresponding to the viewpoint in response to the corresponding incremented level of brightness of that pixel defined in the boundary area  740 . As illustrated in  FIG. 7 , the processor may visualize the illumination effect so that the changed or adjusted brightness of a pixel that is relatively distant from the light source  710  and the boundary in the boundary area  740  is relatively low or zero. 
       FIG. 8  illustrates an example in which three light sources  811 ,  812  and  813  exist at a left, center and right side, respectively, in a virtual space. For ease of description, the light source  811 , the light source  812  and the light source  813  are referred to hereinafter as a first light source, a second light source and a third light source, respectively. 
     In an example, the processor may visualize, on a display  800 , a brightness and a color of a first boundary area by overlapping a brightness and a color of a second boundary area in a corresponding overlapping area in response to an overlap between the first boundary area of the illumination, e.g., produced by the light source, and the second boundary area of the illumination, e.g., produced by the second light source. 
     As illustrated in  FIG. 8 , respective boundary areas in which illumination effects by each light source  811 - 813  are visualized may overlap, and the processor may additionally reflect a brightness increment produced by another light source in addition to a brightness increment produced by a corresponding light source in an overlapping area. For example, in an area in which the first boundary area of the first light source  811  overlaps the second boundary area of the second light source  812 , the processor may increase the brightness of a pixel corresponding to boundary areas in a scene corresponding to a viewpoint by adding an incremental level of brightness produced by the first light source  811  and an incremental level of brightness produced by the second light source  812  with respect to pixels in the overlapping area. 
     The processor may additionally reflect a color change caused by another illumination produced by another light source, e.g., the third light source in addition to a color change caused by the corresponding illumination. For example, in response to the illumination produced by light source  811  being set as red and the illumination produced by the second light source  812  being set as green, the processor may also display a yellow color in the area in which the illumination produced by the first light source  811  overlaps the illumination produced by the second light source  812 . 
       FIG. 9  illustrates an example in which an object  990  is disposed in an illumination area  920  produced by illumination light source  910  in a virtual space. 
     A boundary area  940  illustrated in  FIG. 9  is a partial area of the illumination area  920  including a boundary of the illumination area  920 . For example, the processor may determine the boundary area  940  based on a position, a direction, and a threshold angle of the light source  910  as described above. 
     As illustrated in  FIG. 9 , even when the object  990  is positioned in the illumination area  920 , an illumination effect may be visualized through the boundary area  940 . Thus, a device for displaying an illumination may specifically visualize the illumination effect in lieu of interrupting representation of the object  990  on a display  900 , e.g., without adjusting a brightness of pixels of the object  550 . 
     In an example, the device for displaying the illumination may specifically visualize a background, an object, and a path of a light produced by a light source in lieu of interrupting a highlighting effect to be applied to the object. The device for displaying the illumination may be, or be included in, a mobile device, for example, a smartphone or a tablet, and may visualize a path of a spotlight, without a complex physical operation, using a central processing unit (CPU), a graphic processing unit (GPU), and standard graphics software included in the mobile device. 
       FIG. 10  illustrates an example in which an extended boundary area is formed in response to two light sources  1011  and  1012  arranged at a right side and a left side, respectively, of a virtual space. For ease of description, in a display  1000 , the light source  1011  at the left side is referred to hereinafter as a first light source, and the light source  1012  at the right side is referred to hereinafter as a second light source. A boundary area of the first light source  1011  is referred to hereinafter as a first boundary area  1021 , and a boundary area of the second light source  1012  is referred to hereinafter as a second boundary area  1022 . 
     The processor may generate an extended boundary area in response to an overlap between the first boundary area and the second boundary area. For example, as illustrated in  FIG. 10 , the processor may extend the first boundary area  1021  and the second boundary area  1022  based on overlapping areas therebetween. More specifically, the processor may determine a range of an extended boundary area  1030  based on intensity of the first light source  1011  and the second light source  1012 , a length of a boundary of each of the first light source  1011  and the second light source  1012 , and distances from the first light source  1011  and the second light source  1012 . For example, the processor may determine the range of the extended boundary area  1030  to be relatively wide in response to the intensity of the illuminations produced by the first light source  1011  and the second light source  1012  being high. In another example, the processor may determine the range of the extended boundary area  1030  to be relatively wide in response to a close relative distance, for example, a distance between a boundary of a first illumination area (produced by the first illumination  1011 ) and a boundary of a second illumination area (produced by the second illumination  1012 ), between boundaries of each illumination area (produced by the respective illuminations  1011  and  1012 ). Even when a predetermined pixel does not correspond to a boundary area in the first illumination area, the predetermined pixel may correspond to an extended boundary area due to the overlap between the first illumination area and the second illumination area. 
     The processor may assign a weight to the incremental levels of brightness for pixels in an overlapping area in response to an overlap between the first boundary area and the second boundary area. For example, the processor may add an incremented level of the first boundary area  1021  to an incremented level of the second boundary area  1022  with respect to a pixel in an overlapping area, and assign a weight to the incremental level of the brightness resulting from the addition, in response to an overlap between the first boundary area  1021  of the first light source  1011  and the second boundary area  1022  of the second light source  1012 . In an example, the processor may assign a weight to an increment level of a brightness in a boundary area of a light source, such that the overlapping areas may be represented to be brighter. 
     In an example, a blurring effect of a light may be applied to assigning a weight with respect to a brightness in the extended boundary area  1030  and the overlapping areas, so that a user may easily recognize each path of light even when paths of lights by each illumination overlap. 
       FIG. 11  illustrates an example in which an extended boundary area is formed in based on three light sources arranged in a virtual space. For ease of description, in a display  1100 , a light source  1111  at a left side is referred to hereinafter as a first light source, an illumination  1112  at a center is referred to hereinafter as a second light source, and an illumination  1113  at a right side is referred to hereinafter as a third light source. 
     The processor may form an extended boundary area in response to an overlap between a boundary area of the first light source  1111 , a boundary area of the second light source  1112 , and a boundary area of the third light source  1113 . Based on a similar method as illustrated in  FIG. 10 , the processor may extend the boundary areas of the first light source  1111 , the second light source  1112  and the third light source  1113 . Since boundary areas overlap due to the first light source  1111 , the second light source  1112 , and the third light source  1113  in  FIG. 11 , the processor may determine the extended boundary area resulting from the overlap to be relatively wide or determine an increment level of a brightness in a pixel in the boundary area to be relatively high, in comparison to the extended boundary area of  FIG. 10 . A color of the first light source  1111 , a color of the second light source  1112 , and a color of the third light source  1113  may be combined and visualized in an area in which boundary areas of each of the first light source  1111 , the second illumination  1112 , and the third illumination  1113  overlap. The foregoing is a representation in which a blurring effect and an adding effect of a brightness are mutually applied in response to an overlap of lights, and a user may recognize an overlapping illumination area as a path of a light. 
       FIGS. 12 through 15  are block diagrams illustrating examples of a device for displaying an illumination. 
     As illustrated in  FIG. 12 , a device  1200  for displaying an illumination includes a processor  1210  and an image display apparatus (or “display”)  1220 . For example, the device  1200  for displaying the illumination may be a smartphone or a tablet personal computer (PC). 
     The processor  1210  determines, based on illumination information, an illumination area to which a light produced by illumination light source assigned in a virtual space is projected, and defines a boundary area including a boundary and a portion of the determined illumination area. The processor  1210  controls the display  1220  to visualize an illumination effect with respect to the boundary area. According to one or more embodiments, the processor  1210  may determine the illumination area and the boundary area by implementing any, or any combination, of the methods of  FIGS. 1 through 11 . 
     The display  1220  visualizes the illumination effect by the illumination with respect to the boundary area. The display  1220  may represent a scene corresponding to a predetermined viewpoint based on viewpoint information. For example, the display  1220  may represent a background and an object arranged in the virtual space as a scene at the predetermined viewpoint. 
     As illustrated in  FIG. 13 , a device  2200  for displaying an illumination is similar to the device  1200  of  FIG. 12 , but further includes a memory  1330 . The memory  1330  stores a brightness adjustment map to define an increment level of a brightness in a pixel in a boundary area in a predetermined form. The memory  1330 , or another non-transitory medium, stores a program including a command for controlling one or more processing devices to execute any, or any combination, of the methods of displaying the illumination illustrated in  FIGS. 1 through 11 , for example. The memory  1330  temporarily or semi-permanently stores data required for executing the method of displaying the illumination, for example, illumination information and information associated with an illumination area, a boundary area, and an increment level of a brightness. 
     As illustrated in  FIG. 14 , a device  3200  for displaying an illumination is similar to the device  2200  of  FIG. 13 , but further includes a communicator  1440 . The communicator  1440 , via a wired connection or wirelessly, receives data required for executing the method of displaying the illumination, such as any, or any combination, of the methods of  FIGS. 1-11 . For example, the communicator  1440  receives the illumination information to define an illumination in a virtual space from an external source. 
     As illustrated in  FIG. 15 , a device  4200  for displaying an illumination is similar to the device further includes an input receiver  1550 . The input receiver  1550  receives the data required for executing the method of displaying the illumination from the user. For example, the input receiver  1550  receives the illumination information to define the illumination from the user. 
     Although specific examples of devices  1200 ,  2200 ,  3200  and  4200  are described above, a configuration of a device for displaying an illumination is not limited to the described examples. For example, a device for displaying an illumination may include the processor  1210  and the display  1220  illustrated in  FIG. 11 , and may further include one or more of the memory  1330 , the communicator  1440 , and the input receiver  1550 . 
     The image display apparatus described herein may be implemented using a liquid crystal display (LCD), a light-emitting diode (LED) display, a plasma display panel (PDP), a screen, a terminal, or any other type of display known to one of ordinary skill in the art. A screen may be a physical structure that includes one or more hardware components that provide the ability to render a user interface and receive user input. The screen may include any combination of a display region, a gesture capture region, a touch-sensitive display, and a configurable area. The screen may be part of an apparatus, or may be an external peripheral device that is attachable to and detachable from the apparatus. The display may be a single-screen display or a multi-screen display. A single physical screen may include multiple displays that are managed as separate logical displays permitting different content to be displayed on separate displays even though they are part of the same physical screen. 
     The user interface may provide the capability of inputting and outputting information regarding a user and an image. The user interface may include a network module for connecting to a network and a universal serial bus (USB) host module for forming a data transfer channel with a mobile storage medium. In addition, the user interface may include one or more input/output devices, such as a mouse, a keyboard, a touch screen, a monitor, a speaker, a screen, or a software module for controlling the input/output device. 
     The apparatuses, units, modules, devices, and other components illustrated in  FIGS. 12-15  (e.g., the processor  1200 , display  1220 , memory  1330 , communicator  1440  and input receiver  1550 ) that perform the operations described herein with respect to  FIGS. 1-11  are implemented by hardware components. Examples of hardware components include controllers, sensors, generators, drivers, memories, comparators, arithmetic logic units, adders, subtractors, multipliers, dividers, integrators, and any other electronic components known to one of ordinary skill in the art. In one example, the hardware components are implemented by computing hardware, for example, by one or more processors or computers. A processor or computer is implemented by one or more processing elements, such as an array of logic gates, a controller and an arithmetic logic unit, a digital signal processor, a microcomputer, a programmable logic controller, a field-programmable gate array, a programmable logic array, a microprocessor, or any other device or combination of devices known to one of ordinary skill in the art that is capable of responding to and executing instructions in a defined manner to achieve a desired result. In one example, a processor or computer includes, or is connected to, one or more memories storing instructions or software that are executed by the processor or computer. Hardware components implemented by a processor or computer execute instructions or software, such as an operating system (OS) and one or more software applications that run on the OS, to perform the operations described herein with respect to  FIGS. 1-11 . The hardware components also access, manipulate, process, create, and store data in response to execution of the instructions or software. For simplicity, the singular term “processor” or “computer” may be used in the description of the examples described herein, but in other examples multiple processors or computers are used, or a processor or computer includes multiple processing elements, or multiple types of processing elements, or both. In one example, a hardware component includes multiple processors, and in another example, a hardware component includes a processor and a controller. A hardware component has any one or more of different processing configurations, examples of which include a single processor, independent processors, parallel processors, single-instruction single-data (SISD) multiprocessing, single-instruction multiple-data (SIMD) multiprocessing, multiple-instruction single-data (MISD) multiprocessing, and multiple-instruction multiple-data (MIMD) multiprocessing. 
     The methods illustrated in  FIGS. 1, 2 and 4  that perform the operations described herein with respect to  FIGS. 3 and 5-15  are performed by computing hardware, for example, by one or more processors or computers, as described above executing instructions or software to perform the operations described herein. 
     Instructions or software to control a processor or computer to implement the hardware components and perform the methods as described above are written as computer programs, code segments, instructions or any combination thereof, for individually or collectively instructing or configuring the processor or computer to operate as a machine or special-purpose computer to perform the operations performed by the hardware components and the methods as described above. In one example, the instructions or software include machine code that is directly executed by the processor or computer, such as machine code produced by a compiler. In another example, the instructions or software include higher-level code that is executed by the processor or computer using an interpreter. Programmers of ordinary skill in the art can readily write the instructions or software based on the block diagrams and the flow charts illustrated in the drawings and the corresponding descriptions in the specification, which disclose algorithms for performing the operations performed by the hardware components and the methods as described above. 
     The instructions or software to control a processor or computer to implement the hardware components and perform the methods as described above, and any associated data, data files, and data structures, are recorded, stored, or fixed in or on one or more non-transitory computer-readable storage media. Examples of a non-transitory computer-readable storage medium include read-only memory (ROM), random-access memory (RAM), flash memory, CD-ROMs, CD-Rs, CD+Rs, CD-RWs, CD+RWs, DVD-ROMs, DVD-Rs, DVD+Rs, DVD-RWs, DVD+RWs, DVD-RAMs, BD-ROMs, BD-Rs, BD-R LTHs, BD-REs, magnetic tapes, floppy disks, magneto-optical data storage devices, optical data storage devices, hard disks, solid-state disks, and any device known to one of ordinary skill in the art that is capable of storing the instructions or software and any associated data, data files, and data structures in a non-transitory manner and providing the instructions or software and any associated data, data files, and data structures to a processor or computer so that the processor or computer can execute the instructions. In one example, the instructions or software and any associated data, data files, and data structures are distributed over network-coupled computer systems so that the instructions and software and any associated data, data files, and data structures are stored, accessed, and executed in a distributed fashion by the processor or computer. 
     While this disclosure includes specific examples, it will be apparent to one of ordinary skill in the art that various changes in form and details may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered in a descriptive sense only, and not for purposes of limitation. Descriptions of features or aspects in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if the described techniques are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined in a different manner, and/or replaced or supplemented by other components or their equivalents. Therefore, the scope of the disclosure is defined not by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be construed as being included in the disclosure.