JPH04310930A - Exposure arithmetic device for camera - Google Patents

Abstract

PURPOSE:To offer the exposure arithmetic device for a camera which can always obtain proper exposure. CONSTITUTION:A photometry means 6 which divides a field to be photographed into plural areas, executes the photometry thereof and outputs a photometry signal including information related on the color of an object existing in the respective areas, a grouping means 11 which groups the plural areas on condition that the objects which are mutually adjacent and whose colors are similar exist based on the photometry signal from the photometry means 6, a position arithmetic means for the centroid 14 which respectively obtains the positions of the centroid of the respective grouped groups in the field to be photographed, a brightness value arithmetic means 13 which calculates the brightness values of the respective groups based on the respective photometry signals from the photometry means 6 and an exposure value arithmetic means 15 which excepts the high-brightness group which has the centroid whose position is comparatively high and calculates an exposure value based on the brightness values of the groups other than the high-brightness group are provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure calculation device used in an AE camera.

0002

2. Description of the Related Art A conventional exposure calculation method is disclosed, for example, in Japanese Patent Laid-Open No. 1-231034. To explain this method using FIG. 22, first, a substantially dogleg-shaped region 51 including three corners is cut (excluded) from the photographic screen (field) 50. Two dogleg-shaped areas can be set for the photographing screen 50, and the brighter of the two is set as the target for cutting. Next, the brighter doglegged region 53 is similarly cut from the remaining region 52, and this process is repeated thereafter. As a result, the remaining rectangular areas gradually become smaller, leaving the darkest area 56 at the end. Then, an exposure value is calculated based on the brightness of this darkest area 56.

[0003] In other words, in a general outdoor shooting scene, the main subject is relatively dark and the background (for example, the sky) is considered to be bright, so the above processing is used to grasp the approximate position of the main subject and extract the area corresponding to the sky. The exposure value is determined only by the brightness of the main subject. This increases the possibility that the main subject will be properly exposed.

0004

[Problems to be Solved by the Invention] However, in the above-mentioned conventional method, the shape of the last remaining area 56 is always rectangular, while the main subject is not necessarily rectangular. This cannot be said to be a calculation, and there is a risk that the exposure will be inappropriate. Also, if the main subject exists in both shadow and sunlight, the sunlight part will be cut out when calculating the exposure.
In this case as well, inappropriate exposure occurs as described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exposure calculation device for a camera that can always obtain proper exposure.

[0006]

[Means for Solving the Problems] To explain this in conjunction with FIG. 1 showing an embodiment, the present invention measures light by dividing a field into a plurality of regions, and calculates the color of the object existing in each region. Photometric means 6 each outputting a photometric signal including related information
a grouping means 11 for dividing a plurality of areas into groups based on the photometric signal from the photometry means 6 on the condition that there are objects that are adjacent to each other and have similar colors; A center of gravity calculation means 14 for calculating the position of the center of gravity within the field, a brightness value calculation means 13 for calculating the brightness value of each group from each photometric signal of the photometry means 6, The exposure value calculating means 15 excludes the brightness group and calculates the exposure value based on the brightness values of the remaining groups, thereby solving the above problem.

[0007]

[Operation] The photometering means 6 divides the field into a plurality of regions and measures the light, and outputs a photometry signal containing information related to the color of the object present in each region. Grouping means 1
1 divides a plurality of regions into groups based on a photometric signal from the photometric means 6 on the condition that there are objects that are adjacent to each other and have similar colors. The center of gravity position calculation means 14 is
The position of the center of gravity in the field of view of each of the divided groups is determined, and the brightness value calculation means 13 calculates the brightness value of each group from each photometry signal from the photometry means 6. Then, the exposure value calculation means 15 excludes groups having relatively high centers of gravity and high brightness, and calculates exposure values based on the brightness values of the remaining groups. According to this method, the subject is divided into multiple areas and grouped based on whether they have similar colors, so the main subject can be reliably recognized even if it straddles the shadow and the sunlight. The shape of the subject can be accurately determined, and exposure calculations are performed by cutting out areas other than the main subject, so images can always be taken with the correct exposure.

[0008] In the section of the means and effects for solving the above-mentioned problems that explains the structure of the present invention, figures of embodiments are used to make the present invention easier to understand. It is not limited to.

[0009]

[Embodiment] An embodiment of the present invention will be explained with reference to FIGS. 1 to 21. FIG. 1 is a block diagram showing the overall configuration of an exposure calculation device for a camera according to the present invention. Part of the subject light that passes through the photographic lens 1 and is guided into the camera body is reflected upward by the main mirror 2, and the reflected light passes through the focusing plate 3 and pentaprism 4 that constitute the finder optical system. A part of the light is observed through an eyepiece (not shown), and the other part is received by the photometric element 6 via the photometric lens 5. The photometric element 6 has three photometric outputs R and G, as will be described in detail later.
, B, and these are input to the photometry circuit 7. The photometric circuit 7 calculates and outputs a brightness value according to the input signal.

FIG. 2 is an enlarged view of the photometric element 6. This photometric element 6 is divided into a total of 247 divided elements 6A, 13 vertically and 19 horizontally, and each divided element 6A corresponds to each divided photometric area obtained by similarly dividing the field of view into 247. As shown in FIG. 3, each dividing element 6A further includes 6a and 6b.
, 6c, each of which is equipped with a filter having wavelength characteristics R, G, and B as shown in FIG. 4(a). This is similar to the sensitivity characteristics of three primary color filters used in color televisions, for example. The photometry circuit 7 uses the outputs R, G, and B (this corresponds to the photometry signal) of each dividing element 6A, and calculates BV=0.30R+0.59G+0.11.
B...Due to (1), Figure 4
A sensitivity distribution BV as shown in (b) is obtained. This BV corresponds to the brightness value.

FIG. 5 shows a generally known xy chromaticity diagram, in which three points GP (Gx, Gy), BP
(Bx, By) RP (Rx, Ry) is set in advance according to the filter characteristics of the photometric element 6, and from the photometric signals R, G, B, x=R/(R+G+B)
...
・(2) y=G/(R+G+B)

...If you find x and y using (3), this x,
The subject color of the area corresponding to each dividing element 6A can be known by where in the triangle connecting the above three points y exists.

In other words, this triangle is defined as a point (0.33,0
．． The XY coordinate system rotated by θ around 33) (Fig. 6
), the interior of the triangle is divided into seven areas (white area E1, yellow area E2, yellow-green area E3, green area E4, blue area E5, purple area E6, and red area E7) as shown in Figure 6. can. Here, the circle that partitions the white area E1 is X2+Y2=r2 (for example,
r=1.15), and the straight lines L1 and L2 are obtained by the formula, for example, Y=√(3), and the straight lines L3 and L4
are obtained by Y=-√(3). Further, the numbers in each area are color numbers, which are used in the processing described later.

[0013] On the other hand, the X and Y coordinates in this XY coordinate system are calculated as follows using the above x and y:
sinθ...(4) Y=-(x-0.33
) sin θ + (y-0.33) cos θ (5)
(However, sin θ=(Ry-By)/√{(Rx-B
x)2+(Ry-By)2}), and if the calculated coordinates (X, Y) are included in the yellow area E2, for example, it can be determined that the subject color is yellow. Note that in this specification, the square root of any formula is expressed as √(
(formula) or √{formula}.

Further, in FIG. 6, the triangles are shown as equilateral triangles for convenience, but they may not be equilateral triangles depending on the characteristics of the filter. Furthermore, the above-mentioned dividing element 6A is divided into 6a, 6b, and 6c from the left as shown in FIG. do not have. However, since the division of the photometric elements is very fine as shown in FIG. 2, the amount of deviation in the positions of 6a, 6b, and 6c is very small, and there is no problem even if it is assumed that the same portion is being photometered. Furthermore, if the divided shape of the element 6A is made into a houndstooth pattern as shown by 6A' in FIG. 3(B),
It is possible to further reduce deviations in the photometric portion due to color differences.

Reference numeral 10 in FIG. 1 is a control circuit, and this control circuit 10 controls the above-mentioned plurality of objects based on the photometry signal from the photometry circuit 7 on the condition that there are objects adjacent to each other and of similar colors. A grouping unit 11 that divides the dividing element 6A, that is, a photometric area into groups, and a group number calculation unit 1 that calculates the number of groups from the output of the grouping unit 11.
2, a brightness value calculation unit 13 that calculates the average brightness value of each group based on the output of the photometry circuit 7, a barycenter position calculation unit 14 that calculates the center of gravity position in the field of each group, and The exposure value calculating section 15 calculates an exposure value based on outputs from each section. Reference numeral 8 denotes an exposure control circuit, which drives the aperture 21 and shutter 22 based on the exposure value calculated by the exposure calculation section 14 to perform photographing.

Next, the procedure of exposure calculation control by the control circuit 10 will be explained based on the flowcharts shown in FIGS. 7 to 19. 7 shows the main program, and FIGS. 8 to 19 show subroutine programs showing details of each process in FIG. 7. When a release button (not shown) is operated, the program in FIG. 7 is started. Ru. First, in step S1, a variable n for counting the number of groups is reset to zero, followed by color number assignment processing (step S2), grouping processing (step S3), group number calculation processing (step S4), and gravity center position calculation. processing (step S5), brightness value calculation processing (step S6), exposure value calculation processing (step S
7), the exposure control process (step S8) is performed in order, and then the process ends.

FIGS. 8 and 9 are subroutine flowcharts showing details of the color number assignment process in step S2, and this process and the next grouping process are controlled by the grouping section 11. The processing details are as described in 2 above.
The object color (color number) corresponding to each of the 47 divided photometric elements 6A is substituted into the variable C (h, v),
First, in step S201 of FIG. 8, the variables h and v are set to "
1”. Next, in step S202, the photometric signals R(h,v), G(h,v), B(h,v) corresponding to h and v among the photometric signals of the plurality of photometric elements 6A are sent via the photometric circuit 7. Read and calculate X and Y using equations (2) to (4) above.

Here, h indicates the address in the horizontal direction of the divided photometric element 6A in FIG.
Similarly, v indicates the address in the vertical direction, from bottom to top, 1, 2, . . . , 13. That is, for example, the photometric signal corresponding to the lower left photometric element 6A is R(1,1
), G(1,1), B(1,1), and the photometric signal corresponding to the upper right photometric element 6A is R(19,13), G
(19, 13), B(19, 13).

Next, in step S203, X2+Y2<
It is determined whether or not r2. This determination is a determination as to whether or not the above-mentioned X and Y are within the circle shown in FIG. 6, that is, the white area E1. If step S203 is affirmed, step S20
In step 4, the color number "1" indicating white is assigned to C(h,v). If step S203 is negative, the process proceeds to step S205, and it is determined whether Y<√(3)X and X≧0. This is a determination as to whether or not X and Y are included in the yellow area E2. If it is affirmative, step S206
The color number "2" indicating yellow is assigned to (h, v), and if the result is negative, the process advances to step S207.

In step S207, it is determined whether or not X and Y are included in the yellow-green area E3 based on whether Y≧√(3)X and Y≧−√(3)X, and the result is affirmative. In step S208, C(h,v) is assigned a color number "yellow-green".
3'' is substituted, and if the result is negative, the process advances to step S209. In step S209, it is determined whether or not X and Y are included in the green area E4 based on whether Y<-√(3)X and X≧0. If affirmative, C(h
, v) is substituted with the color number "4" indicating yellow-green, and if the result is negative, the process advances to step S211.

[0021] In step S211, X<0 and Y≧√
(3) Determine whether or not X and Y are included in the blue area E5 based on whether or not
In step 2, assign the color number "5" indicating blue to C(h,v),
If negative, the process advances to step S213. Step S21
3, it is determined whether or not X and Y are included in the purple area E6 depending on whether Y<√(3)X and Y<−√(3)X, and if it is affirmative, C is (h,v)
The color number "6" indicating purple is assigned to , and if the answer is negative, the process advances to step S215. In step S215, C(h,
Assign the color number "7" indicating red to v). Then, steps S204, S206, S208, S210, S2
12, S214, and S215 are followed by step S21 in FIG.
Proceed to step 6.

Substitution of this color number is performed in step S2 of FIG.
17, h is incremented by 1, and h=1 in step S216.
9 is determined, that is, first for one column of dividing elements 6A, and when step S216 is affirmed, h=
1 and increments v by 1, and the same process is performed for the next column of dividing elements 6A. Then, in step S218, v=1
3 is determined, that is, all 247 divided elements 6A
When the color number is assigned to , the process returns to the process of FIG. 7, and the grouping process of step S3 is performed.

FIGS. 10 to 15 are subroutine flowcharts showing details of the grouping process. In FIG. 10, in step S21, the color number "1" is set as an initial value in the variable C, and then in step S22, h and v are reset to the initial value "1". In step S23, C
It is determined whether (h, v)=C or not. If negative, the process proceeds to step S31, and if affirmative, the process proceeds to step S24. v=1 is determined in step S24, and then in step S2
If h=1 is determined in step S26, that is, in the case of processing for the leftmost photometric element 6A at the bottom stage, step S26
Proceed to group update processing.

If it is determined in step S25 that h≠1, that is, if the process is for the photometric element 6A that is at the bottom but not the leftmost, the process proceeds to group discrimination process 1 in step S27. Furthermore, if v≠1 is determined in step S24, and then h=1 is determined in step S28, that is, in the case of processing for the leftmost photometric element 6A other than the bottom row, the process proceeds to group discrimination processing 2 of step S29. , if h≠1 is determined in step S28, that is, the photometric element 6 that is not on the bottom row and is not on the leftmost side
In the case of processing for A, the process advances to group discrimination processing 3 in step S30.

Here, in the process shown in FIG. 10, it is determined whether the subjects in the photometric areas to the left and directly below have similar colors to the subjects in the area, and if they are similar in color, they are grouped into the same group. Is going. However, for example, if it is the leftmost element on the bottom row, there is nothing to compare it to, and if it is on the bottom row but not the leftmost element, it can only be compared with its neighbor on the left.
Furthermore, if it is the leftmost position other than the bottom row, it can only be compared with the one directly below, and only when it is not the bottom row and the leftmost row, it can be compared with the adjacent left side and directly below. Therefore, as described above, the group discrimination processing differs depending on the position of the divided photometric element 6A.

FIG. 11 shows details of the group update process in step S26. First, in step S41, a variable n for counting the number of groups is incremented by "1", and a flag FLG(n) is set to 1. Next, in step S42, n is assigned to the variable N(h,v), and "1" is assigned to the variable K(n), and then the process returns to FIG. 10. Here, the flag FLG(n) is a variable for determining whether group number n is valid or invalid; when it is 1, it is valid; when it is 0, it is invalid. The reason for using this flag will be explained in detail later. Also N(h
, v) are variables (hereinafter referred to as group numbers) representing which group the divided photometric elements 6A at addresses h and v belong to,
K(n) is a variable representing the number of elements in group n, that is, the number of elements constituting the group.

FIG. 12 shows details of the group discrimination processing 1 in step S27 (FIG. 10). As described above, this process is performed when the photometric element is at the lowest level and not at the leftmost position (comparison is possible only with the adjacent left side). First, in step S51, the color number C (h, y
) is the color number C (h-
1, y). Step S5
If 1 is affirmed, N(h,v)=N(
h-1,v). This is a process in which the element and the element to the left of it are given the same group number. In addition, in this step S53, the number of elements in group n is K(N(h,
v)) is incremented by "1", and then returns to the process of FIG. On the other hand, if step S51 is negative, the group update process of FIG. 11 described above is performed in step S52, and the process returns to the process of FIG. 10.

FIG. 13 shows details of the group discrimination processing 2 in step S29 (FIG. 10). This is a process when the divided photometric element 6A is not at the bottom and is at the leftmost position (comparison is possible only with the one directly below). First, in step S61, the color number C (h, v) regarding the element 6A is It is determined whether the color number is the same as the color number C (h, v-1) of the element 6A one below. If step S61 is affirmed, N(h,v)=N(h,v-1) is set in step S63. This is a process in which the subject color for the element 6A is the same as that of the element 6A directly below. Also, in this step S63, the number of elements in group n is K(N(h, v
)) by "1", and then returns to the process of FIG. On the other hand, if step S61 is negative, the group update process of FIG. 11 described above is performed in step S62, and the process returns to the process of FIG. 10.

FIG. 14 shows details of the group discrimination processing 3 in step S30. This is a process when the photometric element is not on the bottom row and is not on the leftmost side (comparable with the adjacent one on the left and directly below). First, in step S71, the color number C (h, v) for the element is set to one. It is determined whether the color number is the same as the color number C(h-1,v) of the element on the left. If step S61 is negative, the process proceeds to step S72, where the color number C(h,v) of the element one below is the color number C(
h, v-1). If step S72 is negative, group update processing (FIG. 11) is performed in step S73 and the process returns to the process of FIG. 10; if affirmative, the process advances to step S74. In step S74,
N(h,v)=N(h,v-1), and the number of elements in group n, K(N(h,v)), is incremented by "1". Further, if step S71 is affirmed, the same determination as step S72 is made in step S75, and if negative, in step S85, N(h,v)=N(h-1,v
), and the number of elements in group n is K(N(h, v
)) is incremented by "1".

Further, if step S75 is affirmed, the process proceeds to step S76, and it is determined whether the group number of the element 6A to the left of the element 6A is equal to the group number of the element 6A directly below it, that is, N(h,v). =N(h,v-1). If step S76 is affirmed, N(h,v)=N(h-1,v) is set in step S86, and K(N(h,v))=K(N(h-1,v)) +1
shall be. Further, if step S76 is denied, step S76 is denied.
The process proceeds to step 77, and it is determined whether N(h,v)>N(h,v-1).

The reason for performing the judgment process in step S77 will be explained below using FIG. 20. Now, for example, there is a roughly U-shaped object (for example, red) in the field, and as shown in FIG.
Consider the case where the color is red). In this embodiment, as described above, scanning starts from the element 6A with h=1 and v=1 toward the right side, so when the element 6A with h=5 and v=4 is reached, it first detects objects of different colors. This is determined and a new group number is assigned, and when the next element 6A with h=9 and v=4 is reached, it is determined that the object is of a different color and another group number is assigned. In other words, the subject with h=5, v=4 and the subject with h=9, v=4 are connected at the top and are actually the same subject (should be considered the same group)
However, this becomes clear only when the element 6A with h=9 and v=9 is reached, and until then it is counted as a different subject (group). therefore,
It becomes clear that h=9 and v=9 are reached (step S7
6 is denied), it is necessary to combine the groups and correct the group number.

In this embodiment, in this case, the group number is corrected to the smaller one, so the determination in step S77 is first performed. If this is denied, N(h,v)=N(h-1,v) and K(
N(h,v))=K(N(h-1,v))+1,
Next, in step S79, the flag FLG(N(h,v-1
)) is set to "0". That is, since the smaller group number N(h-1, v) is adopted, the larger group number N(h, v-1) is unnecessary and is invalidated. Next, in step S80, N(h, v
-1) and N(h, v) to the variable RN, respectively, and the process proceeds to the group number correction process of step S84. Here, the variable KN is the group number to be deleted by the group merging, and the variable RN is the group number to be left.

On the other hand, if the above step S77 is affirmative, then in step S81 N(h,v)=N(h,v−
1) and K(N(h,v))=K(N(h,v−1)
)+1, and then in step S82 the flag FLG(
N(h-1,v)) is set to "0". Then step S
In step S83, N(h-1,v) is substituted for the variable KN, and N(h,v) is substituted for the variable RN, and the process proceeds to the group number correction process of step S84.

FIG. 15 is a subroutine flowchart showing details of this group number correction process. First, in step S91, K(RN)=K(RN)+K(KN), and then K(KN)=0. That is, the current number of elements K
Number of elements K (KN) of the group newly merged into (RN)
is added to obtain a new number of elements K(RN), and since K(KN) is no longer needed after that, it is reset to zero.

Next, in step S92, the variables Kh and Kv are each reset to "1", and in step S93, N(
Kh, Kv) is the group number KN to be erased. If negative, the process proceeds to step S95, and if affirmative, the remaining group number RN is substituted into N(Kh, Kv) in step S94, and the process proceeds to step S95. Such processing is repeated through steps S95 to S100 until step S99 is affirmed, that is, up to the element 6A (Kh=h, Kv=v) currently undergoing processing. Then, if step S99 is affirmed, FIG.
The process then returns to the process in FIG. 10.

Steps S23 to S in FIG. 10 explained above
30 is performed until step S33 is affirmed through steps S31 to S34, that is, all the divided elements 6A
If step S33 is affirmative, the process advances to step S35. Then, in step S36, the color number C is incremented until step S35 is affirmed, that is, for all color numbers. After that, step S3
If 5 is affirmed, the process returns to the process of FIG.

The above is the detailed content of the grouping process. According to this process, elements 6A that are adjacent to each other and have similar colors
are grouped as one group, and a plurality of such groups are formed depending on the color of the scene (one group if the entire scene is the same color). A group number indicating which group it belongs to is given to each element, and the number of elements is given to each group. Here, the 247 divided photometric elements 6A correspond to the 247 photometric areas obtained by dividing the field as described above, so the grouping of the divided photometric elements 6A is similar to the grouping of the photometric areas. It will be equivalent.

FIG. 16 is a subroutine flowchart showing details of the group number calculation process in step S4 (FIG. 7), and this process and the gravity center position calculation process to be described later are controlled by the gravity center position calculation section 14. Here, the number of groups has been assigned to the variable n by the above process, but
This also includes groups that have become invalid. Therefore, this process calculates the true number of groups excluding invalid groups.

In FIG. 16, first, in step S101, a variable i is initialized to "1" and a variable gn for counting the true number of groups is initialized to zero. Next, in step S102, it is determined whether the flag FLG(i) is 1, that is, whether the group corresponding to i is valid. If invalid, proceed to step S104; if valid, step S103
Then, gn is incremented by "1" and the process proceeds to step S104. In step S104, it is determined whether or not i=n, and if it is negative, i is incremented in step S105, and step S102
If the answer is affirmative, the process returns to the process shown in FIG. As described above, the true number of groups is assigned to gn.

FIG. 17 is a subroutine flowchart showing details of the gravity center position calculation process in step S5 (FIG. 7). In FIG. 17, first, in step S111, i is initialized to 1, and then in step S112, flag FLG (h
) is 1 or not. If it is not 1 (if invalid), the process proceeds to step S121, and if it is 1 (if valid), the process proceeds to step S113. In step S113, h
=1, v=1, hadd=0, vadd=0, and then in step S114, N(h,v)=
i, that is, whether the group number of the element is i.

If step S114 is negative, the process proceeds to step S116; if affirmative, in step S115, h
add=hadd+h, vadd=vadd+v, and proceed to step S116. Such processing is performed until v=13 is determined in step S118, that is, for all elements, and then, in step S120, Sh(
i)=Int(hadd/K(i)+0.5)Sv(i
)=Int(vadd/K(i)+0.5), calculate the coordinates of the center of gravity position for the field of the group corresponding to i. Here, K(i) is the number of elements in the group, and Int indicates truncation.

[0042] In step S121, it is determined whether or not i=n, that is, whether or not the center of gravity positions have been calculated for all groups.If negative, i is incremented in step S122 and the process returns to step S112. If , is affirmed, the process returns to the process of FIG.

FIG. 18 is a subroutine flowchart showing details of the brightness value calculation process in step S6 (FIG. 7), which is controlled by the brightness calculation section 13. In FIG. 18, first, in step S131, i is initially reset to 1, and then in step S132, flag FLG(i)
Determine whether or not is 1. If not 1, step S141
If it is 1, the process advances to step S133. In step S133, h=1, v=1, BVadd=0, and then in step S134, N(h, v)=
Determine whether or not i.

If step S134 is negative, the process proceeds to step S136, and if affirmative, the BV is determined in step S135.
BVadd by add=BVadd+BV(h,v)
seek. Here, BV (h, v) indicates the brightness value of each photometric area, and the photometric signals B, G,
This is a value calculated by the photometry circuit 7 based on R using the above equation (1).

Such processing is performed in step S138 when v=
13, that is, for all the elements 6A, and then in step S140, BVG(i)=
Average brightness value BVG(i) of the group corresponding to i by BVadd/K(i)
Calculate. In step S141, it is determined whether or not i=n, that is, the average brightness value BVG(i) for all groups.
It is determined whether or not has been calculated, and if it is negative, step S
In step S142, i is incremented and the process returns to step S132. If affirmative, the process returns to the process of FIG.

FIG. 19 is a subroutine flowchart showing details of the exposure value calculation process in step S7 (FIG. 7), which is controlled by the exposure value calculation section 15. Figure 19
First, in step S151, it is determined whether the number of groups gn is 1 or not. gn=1 means that the entire scene has the same color, and in this case step S152
In step S153, i=1 is set.

In step S153, the flag FLG(i
) is “1” or not, and if affirmed, BVa=B
The exposure value BVa is determined using VG(i) and the process returns to the process of FIG. 7, and if negative, the process proceeds to step S155. In step S155, it is determined whether or not i=n, and if it is negative, i is incremented in step S156, and step S15
Returning to step 3, if affirmative, the process returns to the process of FIG. That is, in this case, the average brightness value of the entire field becomes the exposure value BVa.

On the other hand, if step S151 is negative, that is, if the number of groups is 2 or more, step S1
The process proceeds to step 57 and initial reset is performed to i=1, j=1, and BVadd=0. Next, in step S158, the flag FL
It is determined whether G(i) is "1" or not. If negative, the process proceeds to step S162; if affirmative, the process proceeds to step S159. In step S159, whether the v coordinate Sv(i) of the center of gravity position of the group corresponding to i is the maximum value of the v coordinates Sv(1), Sv(2), ..., Sv(n) of the center of gravity of each group. Determine whether or not. If step S159 is denied, the process proceeds to step S160, in which the variable j is incremented by "1" and the average brightness BVG(i
) is added to the current BVadd and the process proceeds to step S162 as a new BVadd.

If step S159 is affirmative, the process proceeds to step S161, where BVG(i) is determined as the average luminance value BVG(1), BVG(2), . . . , B
It is determined whether or not the maximum value of VG(n) is reached. Step S16
If 1 is negative, the process proceeds to step S160, and if affirmative, the process proceeds to step S162. In step S162, it is determined whether or not i=n, and if it is negative, step S163
Then, i is incremented and the process returns to step S158. If the answer is affirmative, the exposure value BVa is determined in step S164 as follows: BVa=BVadd/j, and the process returns to the process of FIG.

[0050] That is, the above steps S157 to S164
According to the processing, the most important position in the scene is the highest,
And if there is a group with the highest brightness, it is excluded and the average value of the average brightness of the remaining groups is the exposure value BVa.
becomes.

Thereafter, in step S8 of FIG. 7, an exposure control signal is output to the exposure control circuit 8, and the aperture 21 and shutter 22 are driven based on the exposure value BVa determined in step S7 to perform exposure control (shooting). ) and then terminate the process.

The above is the control procedure by the control circuit 10. To summarize this procedure, with the release operation, first, based on the photometric signal from each divided photometric element 6A, a plurality of divided elements 6A, that is, a plurality of photometric The regions are divided into groups, and then the center of gravity position and average brightness value within the field of view of each group are determined. If there is a group with the highest center of gravity and the highest brightness, that group is excluded and the exposure value is calculated based on the brightness values of the remaining groups. Photography will take place.

As an example, considering a field as shown in FIG. 21(a), the photometric elements 6 are divided into groups 1 to 5 as shown in FIG. 21(b). In this case, group 1, which corresponds to the sky, has the highest center of gravity and the highest brightness, so group 1 is excluded, and the exposure value is calculated from the average of the average exposure values of the remaining groups 2 to 5. is required. In this way, the subject is divided into multiple areas and grouped based on whether or not they have similar colors, making it possible to reliably recognize the main subject even if the main subject straddles the shadow and the sunlight. The shape of the subject can be accurately determined, and exposure calculations are performed by cutting out areas other than the main subject, so that images can always be taken with the correct exposure.

In the configuration of the above embodiment, the photometric element 6
is the photometric means, and the grouping section 11 is the grouping means 11.
The gravity center position calculation section 14 constitutes a gravity center position calculation means, the brightness value calculation section 13 constitutes a brightness value calculation means, and the exposure value calculation section 15 constitutes an exposure value calculation means 15.

In the above, the average brightness value of each group is calculated in the brightness value calculation process shown in FIG. 18, but it is also possible to calculate a brightness value other than the average brightness value, for example, taking into account the minimum brightness value and the area of the group. It's okay. Furthermore, the exposure value is not limited to the average brightness of each group. Furthermore, the group with the highest center of gravity position and the highest brightness is excluded, but the group with the center of gravity higher than a preset predetermined position and the brightness value higher than a predetermined value is excluded. You can do it like this. Furthermore, since the example explained the case where the camera was held in the horizontal position, it was determined that the larger the v-coordinate of the element, the higher the position. However, when the camera is held in the vertical position, the element All you have to do is judge whether it is high or low. Note that whether the camera is in the vertical or horizontal position may be determined by, for example, a well-known mercury sensor. Furthermore, the method of dividing elements (photometric regions) is not limited to the embodiment.

[0056]

According to the present invention, the field is divided into a plurality of regions and photometry is performed, and based on the photometry signal that includes information related to the colors of the objects present in each region, adjacent and similar colors are detected. The multiple areas are divided into groups on the condition that there are objects in the image, and the center of gravity position and brightness value within the field of each group are determined. Since the exposure value is calculated based on the brightness values of the remaining groups, it is possible to reliably recognize the main subject and accurately determine its shape even if the main subject straddles the shadow and sunlight. By cutting out areas other than the main subject and performing exposure calculations, you can always take pictures with the correct exposure.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an exposure calculation device for a camera according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing the configuration of a photometric element.

FIG. 3 is an enlarged view showing two configuration examples of divided elements constituting the photometric element.

FIG. 4 is a diagram showing the characteristics of a filter attached to a photometric element.

FIG. 5 is an xy chromaticity diagram.

FIG. 6 is a diagram showing the positional relationship of each color area.

FIG. 7 is a main flowchart showing a processing procedure.

FIG. 8 is a subroutine flowchart showing details of color number assignment processing.

FIG. 9 is a flowchart following FIG. 8;

FIG. 10 is a subroutine flowchart showing details of grouping processing.

FIG. 11 is a subroutine flowchart showing details of group update processing.

FIG. 12 is a subroutine flowchart showing details of group discrimination processing 1;

FIG. 13 is a subroutine flowchart showing details of group discrimination processing 2;

FIG. 14 is a subroutine flowchart showing details of group discrimination processing 3;

[Figure 15] Sub-routine showing details of group number correction processing
This is a chin flow chart.

FIG. 16 is a subroutine flowchart showing details of group number calculation processing.

FIG. 17 is a subroutine flowchart showing details of gravity center position calculation processing.

FIG. 18 is a subroutine flowchart showing details of brightness value calculation processing.

FIG. 19 is a subroutine flowchart showing details of exposure value calculation processing.

FIG. 20 is an explanatory diagram illustrating an example of the above group discrimination.

FIG. 21 is an explanatory diagram illustrating an example of the operation of the embodiment.

FIG. 22 is a diagram illustrating a conventional exposure calculation method.

[Explanation of symbols]

6 Photometric element 6A split photometry element 7 Photometry circuit 8 Exposure control circuit 10 Control circuit 11 Grouping section 12 Group number calculation section 13 Brightness value calculation unit 14 Center of gravity position calculation section 15 Exposure value calculation section

Claims (1)

[Claims] 1. A photometric means for dividing a field into a plurality of regions and measuring the light, and outputting a photometric signal containing information related to the color of the subject present in each region, and a photometric signal from the photometric means. a grouping means for dividing the plurality of regions into groups based on the condition that objects adjacent to each other and having similar colors exist, and a center of gravity for determining the center of gravity position within the field of view of each of the divided groups. a position calculation means; a brightness value calculation means for calculating the brightness value of each group from each photometric signal of the photometry means; and a brightness value calculation means for calculating a brightness value of each group from each photometric signal of the photometry means, excluding a group having a relatively high center of gravity and high brightness, and calculating a brightness value of the remaining groups. 1. An exposure calculation device for a camera, comprising: exposure value calculation means for calculating an exposure value based on a luminance value.