Abstract:
A color signal processing circuit comprising an amplification circuit having three gains for amplifying a color signal of red, green and blue color signals and amplifying the red, green and blue color signals, the red, green and blue color signals being generated from an image signal taken by a solid-state imaging device by a color separation; a pull-in determination circuit for judging whether or not the color signal in a two dimensional coordinates for defining the color is positioned within a first pull-in limit region showing a color adjustment region and a second pull-in limit region defined in the first pull-in limit region and contained an origin of the two dimensional coordinates, and determinating the pull-in of a color shown by the color signal into a white color defined as the origin of the two dimensional coordinates; and a gain adjustment circuit for adjusting the gain of the amplification circuit, to thereby pull-in the color shown by the color signal determined the pull-in into the origin of the two dimensional coordinates.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a color signal processing apparatus, a method of the same and a camera apparatus which perform a white balance processing of a color signal of an image taken by a solid-state imaging device such as a.charge coupled device (CCD). 
     2. Description of the Related Art 
     When taking an image by using a solid-state imaging device such as a CCD, a white color in an objective image becomes reddish in results of the image taken under an environment of low color temperature like at indoors, while it becomes bluish in results of the image taken under an environment of high color temperature like at outdoors. 
     The color temperature here is defined as a temperature of blackbody (K) having the same chrominance as a light source for a test. 
     When using a camera apparatus employing such a solid-state imaging device to reproduce a white color from the objective image to appear as an achromatic color in the reproduced image, if the color temperature of the light source changes, the input color white moves along a blackbody emission curve (blackbody locus  2 ) in accordance with changes of a color temperature as shown in FIG.  1 A. In this case, an automatic white balance (AWB) processing is performed to match a white portion of the objective image, that appears to be colored because of the color temperature changes of the light source, to an achromatic white color of a reproduced image. 
     In the automatic white balance processing, in order to remain the colors as they are for the portions originally not being white, it is necessary to prevent erroneously performing white balance processing to any color that was not white in the original objective image. Therefore, a camera apparatus sets a pull-in limit region  3 , shown in FIG. 1B, which limits a range the white balance operation is performed. The white balance processing is performed only when white color is positioned within the pull-in limit region  3 , while the white balance operation is not performed when it is positioned outside the region  3 . 
     Conventionally, the pull-in limit region  3  is set to be a simple rectangular shape, as shown in FIG.  1 B. As a result, a program volume for processing the white balance can be reduced compared with a case with a complex shape. 
     However, when using the rectangular pull-in limit region  3  as shown in FIG. 1B for the automatic white balance processing in the same way as the above camera apparatus, the automatic white balance processing is performed with respect to colors outside the changing direction of the color temperature being along with the blackbody emission curve  2 , as shown in FIG. 1C, and the colors are made to be different from the original. In an example shown in FIG. 1C, the automatic white balance processing is performed to magenta (Mg). 
     To overcome the disadvantage, when using a pull-in limit region  5  which is combination of a plurality of rectangles to be along with the blackbody emission curve  2 , as shown in FIG. 2A, the automatic white balance processing is not performed to colors outside the change direction of the color temperature along with the blackbody emission curve  2 , and, for example, magenta can be remained as it is, as shown in FIG.  2 B. 
     However, in the methods shown in FIGS. 2A to  2 C, the pull-in limit region  5  has six boundary lines, as shown in FIG. 2C, so that when judging if the objective color is inside the pull-in limit region  5  or outside, it is necessary to judge that on which side the objective color is positioned with respect to six boundary lines. Therefore, there is a disadvantage that a volume of the program to perform the automatic white balance processing becomes large and the processing time becomes long. 
     Another methods can be considered which stores all the combinations of R gain and B gain being positioned at predetermined intervals on the blackbody emission curve, judges if an objective color is one of the stored combinations or not, and determines whether or not to perform the automatic white balance processing. In this methods, more highly precise automatic white balance processing can be realized, however, as same as the case in FIGS. 2A to  2 C, there is a disadvantage that the program volume is large and the processing time is long. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a color signal processing circuit, a method of the same and a camera apparatus, which can perform a highly precise automatic white balance processing with a small program volume. 
     According to the present invention, there is provided a color signal processing circuit comprising: an amplification circuit having three gains for amplifying a color signal of red, green and blue color signals and amplifying the red, green and blue color signals, the red green and blue color signals being generated from an image signal taken by a solid-state imaging device by a color separation; a pull-in determination circuit for judging whether or not the color signal in a two dimensional coordinates for defining the color is positioned within a first pull-in limit region showing a color adjustment region and a second pull-in limit region defined in the first pull-in limit region and contained an origin of the two dimensional coordinates, and determinating the pull-in of a color shown by the signal into a white color defined as the origin of the two dimensional coordinates; and a gain adjustment circuit for adjusting the gain of the amplification circuit, to thereby pull-in the color shown by the color signal determined the pull-in into the origin of the two dimensional coordinates. 
     Preferably, the color signal processing circuit further comprises an integration circuit for integrating the color signal to generate an integrated color signal. 
     The pull-in determination circuit judges whether or not the integrated color signal in the two dimensional coordinates is positioned within the first pull-in limit region and the second pull-in limit region, and determines the pull-in of a color shown by the integrated color signal into the white color defined as the origin of the two dimensional coordinates. The gain adjustment circuit adjusts the gain of the amplification circuit, to thereby pull-in the color shown by the integrated color signal determined the pull-in into the origin of the two dimensional coordinates. 
     Preferably, the integration circuit integrates the color signal, every field to generate the integrated color signal. 
     The two dimensional coordinates may be defined by a first axis showing (R+B−2G), where R represents red, B represents blue and G represents green, and a second axis showing (R-B). 
     Preferably the integration :circuit integrates an (R-G) color signal and a (B-G) color signal every field to generate an (R-G) integrated color signal every field and a (B-G) integrated color signal. The pull-in determination circuit calculates the (R-G) integrated color signal and the (B-G) integrated color signal to obtain an (R-B) integrated color signal and an (R+B−2G) integrated color signal, and judges whether or not the (R-B) integrated color signal and the (R+B−2G) integrated color signal in the two dimensional coordinates for defining the color is positioned within the first pull-in limit region and the second pull-in limit region, and determines the pull-in of a color shown by the integrated color signal into the white color defined as the origin of the two dimensional coordinates. The gain adjustment circuit adjusts the gain of the amplification circuit to thereby pull-in the color shown by the integrated color signal into the origin of the two dimensional coordinates. 
     The first pull-in limit region is defined as a first rectangular shape which are defined by first to fourth lines, the first and second lines being parallel to each other and being positioned both sides of a blackbody emission curve in the two dimensional coordinates and passing the origin, and the third and fourth lines being parallel to each other and perpendicular to the first and second lines, and the second pull-in limit region is defined as a second rectangular shape and is smaller than the first pull-in limit region, the second rectangular shape being defined by fifth to eighth lines, the fifth and sixth lines being parallel to each other and to the first and second lines of the first pull-in limit region, and being respectively positioned between the first line and the blackbody emission curve and between the blackbody emission curve and the second line, the seventh and eighth lines being parallel to each other and perpendicular to the fifth and sixth lines, the fifth line of a upper position being defined as a first reference line and the sixth line of a lower position being defined as a second reference line. 
     The color shown by the color signal may be varied to another color shifted from the white color along a blackbody emission curve in the two dimensional coordinates in response to the change of a color temperature. 
     Alternatively, the color shown by the integrated color signal may be varied to another color shifted from the white color along the blackbody emission curve in the two dimensional coordinates in response to the change of a color temperature. The first and second lines defining the first pull-in limit region are parallel to a tangential line of the blackbody emission curve at the origin. 
     Preferably, the solid-state imaging device is a charge coupled device. 
     In the color signal processing circuit of the present invention, only when two dimensional coordinates of the color signal is positioned inside the first pull-in limit region in the two dimensional coordinates and also is positioned inside the second pull-in limit region, the processing for pulling in the color indicated by the color signal to the origin is performed. 
     The second pull-in limit region is closer to the blackbody emission curve compared with the first pull-in limit region. Therefore, compared with the case only using the first pull-in limit region, it can prevented to pull in colors other than white to white more correctly. 
     According to the present invention, there is also provided a method for processing a color signal, including the steps of: amplifying a color signal of red, green and blue color signals by an amplification circuit having three gains for amplifying the red, green and blue color signals, the red, green and blue color signals being generated from an image signal taken by a solid-state imaging device by a color separation; judging whether or not the color signal in a two dimensional coordinates for defining the color is positioned within a first pull-in limit region showing a color adjustment region and a second pull-in limit region defined in the first pull-in limit region and contained an origin of the two dimensional coordinates, and determinating the pull-in of a color shown by the color signal into a white color defined as the origin of the two dimensional coordinates; and adjusting the gain of the amplification circuit, to thereby pull-in the color shown by the color signal determined the pull-in into the origin of the two dimensional coordinates. 
     According to the present invention, there is further provided a camera apparatus comprising: an imaging means including a plurality of solid-state imaging devices for generating an analog image signal of an object; an A/D converter converting the analog image signal to a digital image signal; a primary-color separation circuit for separating the digital converted image signal to a red (R) color signal, a green (G) color signal and a blue (B) color signal; an amplification circuit having three gains for amplifying a color signal of red, green and blue color signals and amplifying the red, green and blue color signals; a pull-in determination circuit for judging whether or not the color signal in a two dimensional coordinates for defining the color is positioned within a first pull-in limit region showing a color adjustment region and a second pull-in limit region defined in the first pull-in limit region and contained an origin of the two dimensional coordinates, and determinating the pull-in of a color shown by the color signal into a white color defined as the origin of the two dimensional coordinates; and a gain adjustment circuit for adjusting the gain of the amplification circuit, to thereby pull-in the color shown by the color signal determined the pull-in into the origin of the two dimensional coordinates. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the accompanying drawings, in which: 
     FIGS. 1A to  1 C are views for explaining a pull-in limit region in a camera apparatus of the related art; 
     FIGS. 2A to  2 C are views for explaining another pull-in limit region in a camera apparatus of the related art; 
     FIG. 3 is a diagram of a system configuration of a camera apparatus of an embodiment of the present invention; 
     FIG. 4 is a diagram of a circuit configuration of an optical detector shown in FIG. 3; 
     FIG. 5 is a graph of an image signal processed by an integrating circuit shown in FIG. 4; 
     FIG. 6 is a block diagram of controller functions shown in FIG. 3; 
     FIGS. 7A and 7B are views for explaining a processing in a comparator shown in FIG. 6; 
     FIGS. 8A to  8 C are graphs for explaining a processing in a pull-in determining circuit shown in FIG. 6; 
     FIG. 9 is a view for explaining relationships between coordinates of (B-Y, R-Y) and coordinates of (R+B−2G, R-B); 
     FIG. 10 is a flow chart for explaining a processing in the camera apparatus shown in FIG. 3; 
     FIGS. 11A to  11 B are views for explaining a case when one reference line is used in other embodiments of the present invention; and 
     FIG. 12 is a view for explaining a case when a pull-in limit region which is combination of a plurality of rectangles is used in another embodiments of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Below, a camera apparatus according to a preferred embodiments of the present invention will be explained with reference to the accompanying drawings. 
     FIG. 3 is a configuration diagram of a system of a camera apparatus  10  of the present embodiment. 
     As shown in FIG. 3, the camera apparatus  10  comprises, for example, a lens  11 , an imaging device  12 , a preamplifier  13 , an analog to digital (A/D) converter  14 , a digital signal processing circuit  25 , an optical detector  27 , a controller  28  and a digital to analog (D/A) converter  36 . 
     The lens  11  projects an image of an object to be imaged (not illustrated) on an image surface of the imaging device  12 . 
     The imaging device  12  comprises, for example, a CCD, converts an image passed through the lens  11  to an electric signal and applies it to the preamplifier  13  as an image signal. 
     The preamplifier  13  sample-holds the image signal from the imaging device  12  and extracts necessary data, and carries out a gain control to adjust it to an appropriate level. The output signal of the preamplifier  13  is output to the A/D converter  14 . 
     The A/D converter  14  converts the output signal form the preamplifier  13  from an analog signal to a digital signal and outputs the digital signal to the digital signal processing circuit  25 . 
     The digital signal processing circuit  25  comprises, for example as shown in FIG. 3, a primary-colors separator  26 , white balance amplifiers  22 R,  22 G and  22 B, a gamma (γ) corrector  23  and a color difference matrix device  24 . 
     The primary-colors separator  26  separates the digital signal from the A/D converter  14  to an R signal S 26   a , G signal S 26   b  and B signal S 26   c  which are primary-colors signals of red (R), green (G) and blue (B), and outputs these signals to the white balance amplifiers  22 R,  22 G and  22 B, respectively. 
     The white balance amplifier  22 R adjusts the gain of the R signal S 26   a  from the primary-colors separator  26  based on an R gain signal S 28   a  from the controller  28  and outputs it as an R signal S 22   a  to the gamma (γ) corrector  23 . 
     The white balance amplifier  22 G adjusts the gain of the G signal S 26   b  from the primary-colors separator  26  based on a G gain signal S 28   b  from the controller  28  and outputs is as a G signal S 22   b  to the gamma (γ) corrector  23 . 
     The white balance amplifier  22 B adjusts the gain of the B signal S 26   c  from the primary-colors separator  26  based on a B gain signal S 28   c  from the controller  28  and outputs it as a B signal S 22   c  to the gamma (γ) corrector  23 . 
     Namely, the amplifying rates (gains) of the white balance amplifiers  22 R,  22 G and  22 B are adjusted in order that the ratio of the R signal S 22   a , G signal S 22   b  and B signal S 22   c  becomes equal based on the R gain signal S 28   a , G gain signal S 28   b  and B gain signal S 28   c  from the controller  28  and the white balance processing is performed in the white balance amplifiers  22 R,  22 G and  22 B. 
     The γ corrector  23  corrects gamma (γ) based on the R signal S 22   a , G signal S 22   b  and B signal S 22   c . A color difference matrix processing is then carried out in the color difference matrix device  24  and a picture image signal S 23  is generated by combining it with a luminance (Y) signal which is not illustrated. 
     The picture image signal S 23  is, through a compressing processing, etc., recorded/stored in a recording medium such as a magnetic recording tape and an magneto-optical tape, or transferred in a wired or wireless form/method. 
     FIG. 4 is a diagram of a circuit configuration of an optical detector  27 . 
     As shown in FIG. 4, the optical detector  27  comprises, for example, subtractors  71  and  72  and an integrating circuit  73 . 
     The subtractor  71  subtracts the G signal S 22   b  from the R signal S 22   a  and outputs an (R-G) signal S 71  to the integrating circuit  73 . 
     The subtractor  72  subtracts the G signal S 22   b  from the B signal S 22   c  and outputs a (B-G) signal S 72  to the integrating circuit  73 . 
     The integrating circuit  73  has, as shown in FIG. 5, a different integration range which is divided into a high luminance portion  41  and a normal luminance portion  42  by an integration slice level  40  based on a luminance level. In the high luminance portion  41 , only (R-G) signal S 71  and (B-G) signal S 72  having higher luminance than the integration slice level  40  are integrated, while only the (R-G) signal S 71  and (B-G) signal S 72  having a lower integration slice level  40  are integrated in the normal luminance portion  42 . 
     Note that it determines that the level is saturated when the luminance is extremely high, accordingly it does not integrate signals having a high luminance limit level of  43  or more. Also, signals having too low luminance is regarded as noise and signals having luminance of less than a low luminance limit level  44  are not integrated. 
     As explained above, there are a variety of limiters and special processings are performed in the optical detector  27  in order that the automatic white balance processing is not erroneously operated in the cases with special conditions (for example, condition of complete mono-color). The optical detector  27  then outputs the (R-G) integrated value signal S 73   a  and the (B-G) integrated value signal S 73   b  obtained by integrating in different integration range of the high luminance portion/normal luminance portion for every field to the controller  28 . 
     Note that although integration was carried out after generating the (R-G) signal S 71  and the (B-G) signal S 72  from the R signal S 22   a , the G signal S 22   b  and B signal S 22   c  in the present example, integration of the R signal S 22   a , the G signal S 22   b  and B signal S 22   c  can be carried out before generating the (R-G) signal S 71  and the (B-G) signal S 72  from the R signal S 22   a , the G signal S 22   b  and B signal S 22   c.    
     FIG. 6 is a block diagram of the controller  28 . 
     The controller  28  comprises, for example as shown in FIG. 6, a comparator  81 , an adder  82 , a subtractor  83 , a pull-in determining circuit  84  and a gain setting circuit  85 . 
     The comparator  81  compares the (R-G) integrated value signal S 73   a  and the (B-G) integrated value signal S 73   b  of the high luminance portions with the (R-G) integrated value signal S 73   a  and the (B-G) integrated value signal S 73   b  in the normal luminance portions input from the optical detector  27 , and outputs the signals closer to 0 as the (R-G) integrated value signal S 81   a  and the (B-G) integrated value signal S 81   b  to the adder  82  and the subtractor  83 . 
     For example in the case shown in FIG. 7A, the (R-G) integrated value signal and the (B-G) integrated value signal of the high luminance portions are output respectively as an (R-G) integrated value signal S 81   a  and (B-G) integrated value signal S 81   b  to the adder  82  and subtractor  83 . 
     The adder  82  adds the (R-G) integrated value signal S 81   a  and (B-G) integrated value signal S 81   b  to generate an (R+B−2G) integrated value signal S 82   a  and outputs the same to the pull-in determining circuit  84 . 
     The subtractor  83  subtracts the (B-G) integrated value signal S 81   b  from the (R-G) integrated value signal S 81   a  to generate an (R-B) integrated value signal S 82   b  and outputs the same to the pull-in determining circuit  84 . 
     The pull-in determining circuit  84  determines whether the position (color) in the (R+B−2G, R-B) coordinates indicated by the (R+B−2G) integrated value signal S 82   a  and (R-B) integrated value signal S 82   b  exists between two reference levels which are defined inside the pull-in limit region. When determined that it exists in the region, a pull-in instruction signal S 84  indicating within the pull-in region is output to a gain setting circuit  85 , while when determined that it does not exist in the region, an pull-in instruction signal S 84  indicating the outside of the pull-in region is output to the gain setting circuit  85 . 
     The gain setting circuit  85  performs the automatic white balance processing when the pull-in instruction signal S 84  indicating within the pull-in region is input and generates an R gain signal S 28   a , G gain signal S 28   b  and B gain signal S 28   c  for pulling in a color indicated by the (R+B−2G) integrated value signal S 82   a  and the (R-B) integrated value signal S 82   b  to the origin “0” shown in FIGS. 8A,  8 B and  8 C. 
     Note that the (B-Y, R-Y) coordinates is used for the illustration in FIGS. 8A,  8 B and  8 C. Here, there is a relationship as shown in FIG. 9 between the (B-Y, R-Y) coordinates and the (R+B−2G, R-B) coordinates. That is, the (R+B−2G, R-B) coordinates is the same as the (B-Y, R-Y) coordinates being rotated around the origin “0” by 45° in the counterclockwise. To express it by a vector, there are relationships of [vector(R-B)=vector(R-Y)−vector(B-Y)]and [vector(R+B−2G)=119×vector(R-Y)+81×vector(B-Y)]. 
     Below, processings in the pull-in determining circuit  84  will be explained in detail. 
     The pull-in determining circuit  84  determines where in the (B-Y, R-Y) coordinates shown in FIGS. 8A,  8 B and  8 C a position (color) in the (R+B−2G, R-B) coordinates indicated by the (R+B−2G) integrated value signal S 82   a  and (R-B) integrated value signal S 82   b  exists. When the position exists inside the pull-in limit region  87  as a first pull-in limit region and between the reference lines  88  and  89 , the pull-in instruction signal S 84  indicating within the pull-in region is output to the gain setting circuit  85 . While in other cases, the pull-in instruction signal S 84  indicating the outside of the: pull-in region is output to the gain setting circuit  85 . 
     Here, a second pull-in limit region is defined by a short side of the pull-in limit region  87  and the reference lines  88  and  89 . 
     The reason for setting the pull-in limit region  87  in this way is to prevent an erroneous operation of pulling in colors which are not originally white into white. 
     Here, the pull-in limit region  87  is a rectangular shape whose long sides are inclined by 135° to the (B-Y) axis in the counterclockwise direction. 
     Note that the blackbody emission curve is a curve passing through the origin “0” and the tangental line thereof at the origin “0” is inclined exactly by 135° to the (B-Y) axis in the counterclockwise direction. Accordingly, the tangental line of the blackbody emission curve at the origin “0” and the long side of the pull-in limit region  87  are in parallel. 
     Since the white color on the objective image changes along with the blackbody emission curve in accordance with the change of the color temperature in the sensed image, it is ideal that the automatic white balance processing is performed only to the color on the blackbody emission curve. 
     However, to determine correctly whether or not a position (color) indicated by the (R+B−2G) integrated value signal S 82   a  and (R-B) integrated value signal S 82   b  exists on the blackbody emission curve, a very large volume of program would be required. 
     Therefore, normally, the rectangular shape pull-in limit region  87  is approximately used. The automatic white balance processing is performed unconditionally to an objective color when the color is inside the pull-in limit region  87 . 
     Further, in the present embodiment, reference lines  88  and  89  in parallel with the tangental line of the blackbody emission curve at the origin “0” are provided inside the square pull-in limit region  87 , as shown in FIG. 8A, and a condition for performing the automatic white balance processing is set to the objective color to exist between the reference lines  88  and  89 . 
     Accordingly, as shown in FIG. 8B, when the objective color  150  is positioned inside the pull-in limit region  87  in the (B-Y, R-Y) coordinates and also is positioned between the reference lines  88  and  89 , the pull-in determining circuit  84  outputs the pull-in instruction signal S 84  indicating within the pull-in region to the gain setting circuit  85 . 
     On the other hand, as shown in FIG. 8C, when the objective color  151  is positioned inside the pull-in limit region  87  in the (B-Y, R-Y) coordinates but is positioned outside the space between the reference lines  88  and  89 , the pull-in determining circuit  84 , while pulling in, outputs the pull-in instruction signal S 84  indicating the outside of the pull-in region to the gain setting circuit  85  when the color comes across the reference lines  88  and  89 . 
     Here, the reference line  89  limits pulling in from the direction where, for example, a color such as magenta is positioned in the upper right quadrant. It is expressed in the formula below in the (B-Y, R-Y) coordinates. 
     
       
         ( R - Y )=−( B - Y )+α  (1) 
       
     
     Namely, the reference line  89  is a straight line in the (B-Y, R-Y) coordinates having a gradient of −1 and the point of intersection with the (R-Y) axis is (0, β). 
     Also, the point (0, β) is positioned higher than the point of intersection of the lower long side of the pull-in limit region  87  and the (R-Y) axis. Furthermore, the reference line  89  is positioned lower than the point of intersection of the blackbody emission curve  2 , a curve being positioned symmetrically with respect to the straight line of (R-Y)=−(B-Y) and the short side of the pull-in limit region  87 . 
     In the present embodiment, β is −18(h), where h represents a hexa-decimal expression. 
     The reference line  88  limits pulling in from the direction where, for example, a color such as green is positioned in the lower bottom quadrant. It is expressed by the formula below. 
     
       
         ( R - Y )=−( B - Y )+β  (2) 
       
     
     Namely, the reference line  88  is a straight line in the (B-Y, R-Y) coordinates having a gradient of −1 and the point of intersection with the (R-Y) axis is (0, β). 
     Also, the point (0, α) is positioned lower than the point of intersection of the upper long side of the pull-in limit region  87  and the (R-Y) axis. Furthermore, the reference line  88  is positioned higher than intersections  90  and  91  with the short side of the pull-in limit region  87 . 
     In the present embodiment, α is +18(h). 
     Below, the operation of the camera apparatus  10  shown in FIG. 3 will be explained. 
     FIG. 10 is a flow chart for explaining the operation of the camera apparatus shown in FIG.  3 . 
     Step S 1 : A sensed image of an object formed on the imaging device  12  via the lens  11  is gain-controlled by the preamplifier  13 , and converted to a digital signal by the A/D converter  14 . The digital signal is separated into R, G and B signals by the primary-colors separator  26  and respectively output to the white balance amplifiers  22 R,  22 G and  22 B. Then the R signal S 22   a , G signal S 22   b  and B signal S 22   c  amplified by the white balance amplifiers  22 R,  22 G and  22 B are output to the optical detector  27 . The optical detector  27  generates the (R-G) integrated value signal S 73   a  and (R-G) integrated value signal S 73   b  based on the R signal S 22   a , G signal S 22   b  and B signal S 22   c  and outputs the same to the controller  28 . 
     Step S 2 : The controller  28  shown in FIG. 6 generates the (R+B−2G) integrated value signal S 82   a  and (R-B) integrated value signal S 82   b  based on the (R-G) integrated value signal S 73   a  and (R-G) integrated value signal S 73   b , and the position of the objective color in the (R+B−2G, R-B) coordinates is specified. 
     Step S 3 : The pull-in determining circuit  84  in the controller  28  determines whether or not the position of the objective color specified in the step S 2  is inside the pull-in limit region  87  shown in FIG.  8 . When determined that it exists inside the pull-in limit region  87 , a processing of step S 4  is carried out, while when determined that it does not exists inside the pull-in limit region  87 , the pull-in instruction signal S 84  indicating the outside of the pull-in region is output to the gain setting circuit  85  shown in FIG.  6  and the pull-in processing is not carried out. 
     In this embodiment, the processing in the controller  28  is (actually) carried out using the (R+B−2G, R-B) coordinates for simplifying calculation, however, the processings are substantially the same as the processing using the pull-in limit region  87  and reference lines  88  and  89  in the (B-Y, R-Y) coordinates explained referring to FIG.  8 . 
     Step S 4 : An [R gain+B gain] with respect to the position specified in the step S 2  is obtained in the pull-in determining circuit  84 . 
     Step S 5 : An [R gain+B gain] of reference lines  88  and  89  shown in FIG. 8 are obtained in the pull-in determining circuit  84 . 
     Step S 6 : The pull-in determining circuit  84  compares the [R gain+B gain] obtained in the step S 4  with the value of [R gain+B gain] of the reference lines  88  and  89  obtained in the step S 5  being added α, and determines whether the latter value is larger or not. When the pull-in determining circuit  84  determines that the latter is larger, that is when the position specified in the step S 2  is lower than the reference line  88  shown in FIG. 8, the precessing of the step S 7  is carried out, while in other cases, the pull-in instruction signal S 84  indicating the outside of the pull-in region is output to the gain setting circuit  85  shown in FIG. 6, and the pulling in processing is not carried out. 
     Step S 7 : The pull-in determining circuit  84  compares the [R gain+B gain] obtained in the step S 4  with the value of [R gain+B gain] of the reference lines  88  and  89  obtained in the step S 5  being subtracted β, and determines whether the former is larger or not. When the pull-in determining circuit  84  determines that the former is larger, that is when the position specified in the step S 2  is higher than the reference line  89  shown in FIG. 8, the pull-in instruction signal S 84  indicating within the pull-in region is output to the gain setting circuit  85  shown in FIG.  6  and the processing of the step S 8  is carried out. While in the case when determined that the former value is not larger, the pull-in instruction signal S 84  indicating the outside of the pull-in region is output to the gain setting circuit  85  shown in FIG. 6, and the pull-in processing is not carried out. 
     Steps S 8  and S 9 : When the pull-in instruction signal S 84  indicating the outside of the pull-in region is input to the gain setting circuit  85 , the automatic white balance processing is performed. In order that the color indicated by the (R+B−2G) integrated value signal S 82   a  and (R-B) integrated value signal S 82   b  is pulled in to the origin “0” shown in FIG. 8, the R gain signal S 28   a , G gain signal S 28   b  and B gain signal S 28   c  for adjusting the R gain, G gain and B gain are generated, which are respectively output to the white balance amplifiers  22 R,  22 G and  22 B shown in FIG. 3 after being converted to a predetermined data form. Due to this, the R signal S 22   a , G signal S 22   b  and B signal S 22   c  are feedback-controlled, so that the picture image signal S 23  to which an appropriate white balance processing is performed is generated. 
     As explained above, according to the camera apparatus  10 , the objective color is pulled in to the origin “0” which indicates white of an acchromatic color only when it exists inside the pull-in limit region  87  in the (B-Y, R-Y) coordinates and exists between the reference lines  88  and  89  at the same time. Therefore, compared with the case where only the pull-in limit region  87  is used, it is possible to prevent performing the white balance processing to colors other than white more correctly. Thus, the picture quality of the sensed image can be improved. 
     Also, according to the camera apparatus  10 , since the reference lines  88  and  89  are simple straight lines, the processing can be realized with a small volume of program. 
     Further, according to the camera apparatus  10 , by adjusting α and β of the reference lines  88  and  89 , the difference of the gains due to the not unified characteristics of the imaging device  12  can be absorbed. Accordingly, a high quality sensed image can be provided steadily. 
     Note that the present invention is not limited to the above embodiments. 
     For example, the reference lines  88  and  89  are straight lines being parallel to the long side of the pull-in limit region  87  in the above embodiment, however, as long as they are defined to be inside the pull-in limit region  87 , straight lines not being parallel with the long side of the pull-in limit region, lines with curves or curves can be used. At this time, patterns of the reference lines are decided by relationships of the processing time required by the white balance processing and the required quality. 
     Also, in the above embodiment, a case of providing two reference lines was explained, however, it is possible to provide only the reference line  88  as shown in FIG. 11A or to provide only the reference line  89  as shown in FIG. 11B depending on conditions. 
     Furthermore, a shape rectangle is used as the pull-in limit region  87  in the above embodiment, however, for example as shown in FIG. 12, the reference lines  160  and  161  can be provided in the pull-in limit region  159  which is combination of a plurality of rectangles. 
     As explained, according to the color signal processing circuit, method of the same and the camera apparatus of the present invention, it is possible to correctly prevent performing the white balance processing to colors other than white. Therefore, picture quality of sensed image can be improved. 
     Also, according to the color signal processing circuit and the camera apparatus of the present invention, the processing can be realized with a small volume program by using a square shape for a first pull-in limit region and straight lines for a second pull-in limit region. 
     Also, according to the color signal processing apparatus, method of the same and the camera apparatus of the present invention, by adjusting the second pull-in limit region, difference of gains due to the not unified characteristics of the solid imaging device can be eliminated.