Abstract:
Provided is a change degree deriving device including a receiving unit that receives an image obtained by capturing an object and a known color body, the known color body including plural color samples each of which has a known colorimetric value, and a position checking section used to check a relative position of the known color body with respect to the object, a conversion rule generating unit that generates a conversion rule used to convert a color of the image received by the receiving unit into a numerical value in a device-independent color space, based on the color samples included in the image received by the receiving unit, and a converting unit that converts a color of the object included in the image received by the receiving unit into a numerical value in the device-independent color space according to the conversion rule.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2016-092708 filed May 2, 2016. 
       BACKGROUND 
     Technical Field 
       [0002]    The present invention relates to a change degree deriving device, a change degree deriving system and a known color body. 
       SUMMARY 
       [0003]    According to an aspect of the invention, there is provided a change degree deriving device including: 
         [0004]    a receiving unit that receives an image obtained by capturing an object and a known color body, the known color body including plural color samples each of which has a known colorimetric value, and a position checking section used to check a relative position of the known color body with respect to the object; 
         [0005]    a conversion rule generating unit that generates a conversion rule used to convert a color of the image received by the receiving unit into a numerical value in a device-independent color space, based on the color samples included in the image received by the receiving unit; and a converting unit that converts a color of the object included in the image received by the receiving unit into a numerical value in the device-independent color space according to the conversion rule. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
           [0007]      FIG. 1  is a diagram illustrating a deterioration measuring system according to an exemplary embodiment of the present invention; 
           [0008]      FIG. 2  is a plan view illustrating a known color body used in the exemplary embodiment of the present invention; 
           [0009]      FIG. 3  is a diagram illustrating a relationship between the known color body and an object used in the exemplary embodiment of the present invention; 
           [0010]      FIG. 4  is a block diagram illustrating hardware of a deterioration measuring device according to the exemplary embodiment of the present invention; and 
           [0011]      FIG. 5  is a flow chart illustrating a processing flow of the deterioration measuring device according to the exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
         [0013]      FIG. 1  is a diagram illustrating a change degree derivation according to an exemplary embodiment of the present invention. Hereinafter, descriptions will be made assuming that a deterioration of an object is measured, and the change degree derivation is replaced by a “deterioration measurement” in the description. 
         [0014]    A known color body  10  is fixed to an object  12  that is, for example, a wall face of a structure through pasting or the like. The known color body  10  includes plural color samples  14 . Also, an object capturing hole  16  is formed at the center of the known color body  10 . 
         [0015]    An image capturing device  18  is a digital camera, a smartphone, a tablet PC, or the like, and captures the known color body  10 . Since the object capturing hole  16  is formed in the known color body  10 , the image capturing device  18  captures the wall face  12  through the object capturing hole  16 , together with the known color body  10 . 
         [0016]    A deterioration measuring device  20 , which is, for example, a personal computer, receives image data obtained by capturing the known color body  10  using the image capturing device  18 , and process the image data. 
         [0017]      FIG. 2  illustrates details of the known color body  10 . 
         [0018]    On the known color body  10 , plural color samples (patches)  14  as denoted by, for example, Nos. 111 to 177 are regularly arranged at predetermined positions. The color samples Nos. 111 to 177 include square color samples Nos. 111, 113, 115 . . . and rectangular color samples Nos. 112, 114, 116 . . . . The square color samples Nos. 111, 113, 115 . . . may include 100% solids of R (red), G (green), B (blue), C (cyan), M (magenta), Y (yellow), W (white), Bk (black), and the intermediate colors thereof. 
         [0019]    Also, the square color samples Nos. 111, 113, 115 . . . include plural deterioration-series color samples. The deterioration-series refer to a series of a gradually deteriorated color in an object to be measured. Here, the color sample No. 142 has a color of the object in a new product state, and the color sample No. 126 has a color in a deteriorated state. The deterioration-series color samples Nos. 142 and 126 are arranged around the object capturing hole  16 , inside peripheral edges. That is, these are placed in an environment close to the object in the vicinity of the object capturing hole  16 . 
         [0020]    The rectangular color samples Nos. 112, 114, 116 . . . are white. The reason that the plural white color samples are arranged as described above is to easily check the occurrence of an illuminance ununiformity such as shadows. 
         [0021]    The object capturing hole  16  is formed in the same shape as that of the square color samples Nos. 111, 113, and 115 . . . . 
         [0022]    The above described color samples Nos. 111 to 177 are color-measured as L*a*b* values in advance. Meanwhile, hereinafter, L*a*b* will be abbreviated as Lab. The Lab is a device-independent uniform color space. The Lab values obtained by color-measuring as described above are stored in a memory  24  of the deterioration measuring device  20  to be described later in a state of being paired with positions of the color samples Nos. 111 to 177. 
         [0023]    Meanwhile, the object capturing hole  16  (denoted by No. 144 in  FIG. 2 ) is unknown data, and thus, is not color-measured, and there is no object to be stored as colorimetric data. 
         [0024]    Also, in the margin portion of the known color body  10 , for example, three position checking holes  36   a ,  36   b , and  36   c  serving as a position checking section are formed. For example, characters, that is, “dark,” “medium,” and “pale” are marked in the vicinity of position checking holes  36   a ,  36   b , and  36   c , respectively. 
         [0025]    The position checking holes  36   a ,  36   b , and  36   c  of the known color body  10  are used when a fixed-point measurement is performed on a deterioration state of the object  12 . 
         [0026]    As illustrated in  FIG. 3 , it is assumed that, for example, the same color that is divided into “dark,” “medium,” and “pale” is painted in the row direction of the object  12 , and the paintings of the same color depth are shifted by a half cycle in the column direction. Here, when the position checking hole  36   a  of the known color body  10  is aligned with “dark” of the object  12 , the position checking hole  36   b  is aligned with “medium” of the object  12 , and the position checking hole  36   c  is aligned with “pale” of the object  12 , the object capturing hole  16  may be aligned with a “dark” portion of the object  12 , thereby performing a fixed-point measurement. 
         [0027]    Also, at least one of the position checking holes  36   a ,  36   b , and  36   c  may be sufficient, and the position checking holes may be formed according to the state of the object  12 . Also, since a portion of the object  12  is captured through the position checking holes  36   a ,  36   b , and  36   c  by the image capturing device  18 , the capturing position of the object  12  may be recorded. 
         [0028]    Also, in the exemplary embodiment, as the position checking section, the position checking holes  36   a ,  36   b , and  36   c  may be used, but the present invention is not limited thereto. For example, “dark,” “medium,” and “pale” portions may be indicated by arrows. Also, instead of characters such as “dark,” “medium,” and “pale,” the same color as that of a portion to be addressed may be formed. When a color paler than other portions is present in the “dark” portion, or a color darker than other portions is present in the “pale” portion, the position checking section may also serve as a determining unit to determine that the known color body  10  is arranged at a wrong position. 
         [0029]      FIG. 4  is a block diagram illustrating the deterioration measuring device  20 . 
         [0030]    The deterioration measuring device  20  includes a data processor  21 . The data processor  21  includes a CPU  22 , the memory  24 , an input interface  26 , and an output interface  28 , which are connected through a control bus  30 . 
         [0031]    The CPU  22  executes a predetermined processing based on a control program stored in the memory  24 . An input device  32  is connected to the input interface  26 . The input device  32  may include a connector that is directly connected to the above described image capturing device  18  to be used for input, or a device to be used for wireless input through a communication. Also, an output device  34  is connected to the output interface  28 . The output device  34  is a display or a printer, through which a result such as processed data is output. 
         [0032]      FIG. 5  is a flow chart illustrating a processing flow of the deterioration measuring device  20 . 
         [0033]    First, in step S 10 , RGB image data of the color samples  14  of the known color body  10  and the object  12  within the object capturing hole  16 , which are obtained through capturing using the image capturing device  18 , are received. 
         [0034]    Meanwhile, the image data to be adopted include an average value of each of RGB in a region near the center within the color sample  14  having the same color. 
         [0035]    In the following step S 12 , a matrix operation is performed. That is, the RGB image data of the color samples  14  received in step S 10  are set as explanatory variables, and a colorimetric value Lab of each of the color samples  14  obtained through colorimetry in advance and stored in the memory  24  is set as an object variable to obtain a matrix through multiple regression. 
         [0036]    For example, as expressed in Equation (1) below, a matrix in multiple regression is obtained, and image data RGB are converted into a colorimetric value Lab. 
         [0000]      [Equation 1] 
         [0000]        t ( L,a,b )= M   t ( R,G,B ,1)( t   : TRANSPOSED MATRIX M IS A  3×10  MATRIX )  (1)
 
         [0037]    Specifically, Equation (2) below is used. 
         [0000]      [Equation 2] 
         [0000]        L =( a 11, a 12, a 13, . . . , a 110) t ( R,G,B,R   2   ,G   2   ,B   2   ,RG,GB,BR, 1) 
         [0000]        a =( a 21, a 22, a 23, . . . , a 210) 
         [0000]        b =( a 31, a 32, a 33, . . . , a 310)  (2)
 
         [0038]    In the following step S 14 , RGB data of an image within the object capturing hole  16  of the known color body  10  captured by the image capturing device  18 , that is, an image of the object  12  are put in the equation obtained in step S 12  to obtain an expected colorimetric value L t a t b t  of the object. 
         [0039]    Meanwhile, in the exemplary embodiment, as expressed in Equation (1), multiple regression is performed by a quadratic equation, but may be performed by a color conversion method such as a three-dimensional table method used in a general color management system instead of the quadratic equation. Also, instead of the multiple regression, a neural network by learning may be used. That is, any method may be used as long as the method is capable of forming color conversion using teacher data (data of explanatory variables and object variables). 
         [0040]    In the following step S 16 , a color difference ΔE between a colorimetric value L 0 a 0 b 0  on the object in a new product state and a colorimetric value L t a t b t  obtained in step S 14  is calculated. As the colorimetric value L 0 a 0 b 0  on the new product state, a value obtained through actual colorimetry in a new product state may be used, or a value of the color sample No. 142 of the known color body  10  may be used. 
         [0041]    For the calculation of the color difference ΔE, for example, Equation (3) below is used. 
         [0000]      [Equation 3] 
         [0000]      Δ E =√{square root over (( L   0   −L   t ) 2 +( a   0   −a   t ) 2 +( b   0   −b   t ) 2 )}  (3)
 
         [0042]    Meanwhile, in the example, as expressed in Equation (2), the color difference ΔE is obtained by an Euclidean distance, but, for example, ΔE00 or the like may be used. 
         [0043]    Then, in the following step S 18 , the measured result is output to the output device  34 , and the process is ended. As the measured result, ΔE calculated in step S 16  may be output as it is. Meanwhile, when ΔE exceeds a predetermined threshold, a message indicating that repairing is needed may be displayed, or a deterioration level, e.g., level 1, level 2, or the like may be output. 
         [0044]    Meanwhile, in the exemplary embodiment, the deterioration measuring device  20  includes a personal computer, but the present invention is not limited thereto. For example, the image capturing device  18  may have all or some of functions of the deterioration measuring device  20 . 
         [0045]    The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.