JP3024231B2 - Photometric calculation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photometric calculation device for calculating an optimum exposure value of a camera.

[0002]

2. Description of the Related Art Conventionally, as a method of obtaining a photometric value in a photographing screen, as shown by a dashed line, a two-dot chain line, a three-dot chain line, and a dotted line in FIG. The average of the photometric values in the image is obtained and used as the photometric value.

[0003]

However, in such a conventional apparatus, photometry is performed in a reduced photometry frame in which the photometry screen is simply reduced in size, so that the shape of the photometry areas to be grouped is determined from the beginning. Therefore, there is a problem that it is not possible to accurately measure the luminance distribution of the subject. The present apparatus is designed to reliably measure the luminance of each subject even when there are a plurality of subjects.

[0004]

According to a first aspect of the present invention, there is provided a photometric device which divides an object field into a plurality of regions and sends out a photometric output for each of the regions, and a photometric device therefor. A photometric area grouping means for comparing the output values of the means and processing areas in which the photometric areas are adjacent to each other and which have similar luminance.

According to a second aspect of the present invention, a photometric unit for dividing a scene into a plurality of regions and transmitting a photometric output for each region, and comparing the output values of the photometric units, the photometric regions are adjacent to each other. Photometric area grouping means for processing areas having similar luminance as the same group, group number calculating means for calculating the number of groups grouped by the grouping means, and calculating an average luminance value within the group The apparatus comprises a group luminance calculating means, a center of gravity calculating means for calculating a center of gravity in a region for each group, and an exposure calculating means for calculating an optimum exposure value from a photometric value at the obtained position of the center of gravity.

[0006]

The portion of the object scene having similar luminance and close to each other is divided into a set of blocks, and photometry is performed for each block. For this reason, the photometric value is known for each block, and if it is determined that a bright object having a high center of gravity and a bright one is the sky, photometry shifted to the brighter side will not be performed.

[0007]

FIG. 1 is a block diagram showing an embodiment of the present invention. Light taken in through an objective lens 1 is detected by a light receiving element 5 through a main mirror 2, a screen 3, and a pentaprism 4. You. The information detected by the light receiving element 5 is supplied to a photometric circuit 6, a group number calculating unit 8, a group luminance calculating unit 9, and a center-of-gravity position calculating unit 10, where predetermined processing is performed, and the information is supplied to an exposure calculating unit 11 to be optimized. The exposure amount is calculated, and the shutter 13 is
And the aperture 14 is controlled.

This device, when photographing a subject as shown in FIG. 2A, forms an image on the surface of a light receiving element 5 composed of a plurality of matrices as shown in FIG. Are treated as one group, the luminance of each group is measured, and the exposure amount is determined. In this case, symbol 20 is group 1, symbol 21 is group 2,
The symbol 22 is treated as a group 3, and the group 1 is determined to be empty because it is bright and at a high position, and is usually excluded from exposure targets. And the one that is below and dark is a person. Usually, an object below the screen is often photographed, and thus the exposure amount may be determined in accordance with the lower object.

The circuit shown in FIG. 1 is a circuit for performing such processing, and the photometric circuit 6 operates to detect the absolute value luminance (BV) of the received light.
2), a circuit for measuring the value), grouping means 7 for grouping similar parts of luminance in adjacent cells among a plurality of light receiving cells shown in FIG. 2 (b) into one group, and group number calculating means 8 for grouping. The group luminance calculating means 9 measures the luminance of each group, and the center-of-gravity position calculating means 10 calculates the center-of-gravity position of each group.

Hereinafter, the operation of the apparatus will be described with reference to flowcharts. Since a number of variables appear in each flowchart, the variables are defined below. (A) x, y... Are variables indicating the address of the light receiving element, and are variables shown in FIG.
In (b), x takes a value from 0 to 19, and y takes a value from 0 to 13. (B) BV (x, y) ・ ・ ・ Brightness value output from the light receiving element (c) B (x, y) ・ ・ ・ ・ Value obtained by rounding BV to an integer (d) N (x, y) ···························· Group number to which the light receiving element belongs. Subtract the number (total number of valid groups). (G) B _min ··· B (x, y) minimum value (h) B _max ··· B (x, y) maximum value ( (1) FLG (n): a flag that takes “1” if the nth group is valid, and “0” if it is invalid (nu) K (n): belongs to the group with group number n Number of elements (R) KN: Group number invalid for variable passed to group number correction subroutine (ヲ) RN: Group valid for variable passed to group number correction subroutine Number (W) S _x (i) ・ ・ ・ Glue Coordinates of the center of gravity of the group in the group of the group number i (x) (f) S _y (i) ・ ・ ・ coordinates of the center of gravity of the group in the group of the group number i (y) (Y) BVG (i) ・ ・ ・ group number i Average luminance value in group (average value of BV (x, y) in group i)

FIG. 3 is a flow chart showing the operation of the main routine of this apparatus. In step 80, a process for setting n = 0 is performed, a subroutine B (x, y) substitution in step 100, and grouping in step 150 Subroutine, group number gn calculation subroutine in step 200, centroid (S _x , Sy) calculation for each group in step 250, step 3
The luminance calculation for each group of 00 and the subroutine processing of the exposure calculation in step 350 are sequentially performed, and then the exposure control in step 81 is performed. Details of each subroutine will be described later.

FIG. 4 shows B (x, y) shown in step 100 of FIG.
It is a flowchart for explaining the substitution subroutine, this processing is obtained by rounding the brightness value BV (x, y) output from the light receiving element to obtain an integer brightness value B (x, y), the maximum value thereof And the minimum value. In this process, x = 1 and y = 1 are set in step 101, and in step 102, an integer luminance value is obtained by performing an operation of B (x, y) = Int {BV (x, y) +0.5}. . The process of step 102 rounds off the brightness output value BV (x, y) of the light receiving element at the x, y coordinates,
It has been converted to an integer. Next, until it is determined in step 103 that x has reached 19, which is the maximum value of the x-coordinate in this embodiment, the value of x is incremented in step 104, and in each case in step 102, the integer luminance value B ( x, y)
Ask for.

When all of the integer luminance values in the x direction are obtained, the determination in step 105 is performed.
Since it is 1, the coordinate in the y direction is incremented by one in step 106, and again in steps 102 to 104.
Is performed, and an integer luminance value of the x coordinate at the y coordinate is obtained. When this process is repeated, step 105 will soon follow.
In step 107, it is determined that y> 13. In step 107, B, which is the maximum value of the integer luminance values B (x, y) obtained so far,
_max and B _min, and B (x, y) in step 100 of FIG.
The assignment subroutine ends.

FIG. 5 is a subroutine for realizing the grouping of step 150 in FIG. First, in step 151, a determination brightness value B serving as a reference for determination is set.
_Is set to B _min obtained in step 107 of FIG. 4, and in step 152, x = 1 and y = 1 are set. And step 153
, The luminance value output by the light receiving element at this coordinate
It is determined whether B (xy) is equal to the determination reference value B set in step 151. At this point, the judgment reference value is set to the lowest luminance value output from the light-receiving element measured earlier, so the probability of coincidence is low at this stage, but it is assumed that the coincidence is easy to understand. The explanation will proceed.

If B (x, y) is equal to B in step 153, here B _min set in step 151, it is determined in step 154 whether or not y = 1, and at this time y = 1 In step 155, it is determined whether or not x = 1. However, since x = 1, in this case, step 1 is performed.
A group update subroutine process of 56 is performed (details of this process will be described later, but this process is performed only when x = 1, that is, only at the lower left end of the screen). Since it is determined in step 157 that x> 19 is not satisfied, the x coordinate is incremented in step 158, and the flow returns to step 153.

Here, in step 153, B (x, y) = B,
That is, description will be made assuming that B _min is determined. In this case, it is determined in step 154 that y = 1, but since the x coordinate has been incremented in step 158, it is determined in step 155 that x = 1 is not satisfied, and the processing of group determination 1 in step 159 is performed. (Details of this processing will be described later, but this processing is performed only at the lower end of the screen).

Thereafter, steps 157 and 1 are performed in the same manner as described above.
After the x coordinate increment process is performed by 58,
The flow returns to step 153, and the same processing as described above is performed. Therefore, it is determined in step 157 that x> 19. However, since it is determined in step 165 that y> 13 is not satisfied, the processing of x = 1, y = y + 1 is performed in step 166, and the flow returns to step 153.

At this stage, in step 154, y = 1
Is determined, and x = 1 is determined in step 167, so that the processing of group determination 2 in step 168 is performed (this processing will be described later, but is the processing of the left end excluding the lower left end of the screen). Thereafter, similarly to the above, the process of increasing the x coordinate is performed in step 158 until the determination of x> 19 is performed in step 157. Therefore, it is determined that step 167 is not x = 1. The processing of determination 3 is performed (this processing is processing of an area excluding the left end and the lower end of the screen, which will be described later).

Thereafter, while repeating the increase in the x coordinate in step 158 and the increase in the y coordinate in step 166, the processing of group determination 2 in step 168 and group determination 3 in step 169 are performed, and y exceeds 13. At step 175, it is determined whether or not B = B _max. However, since the brightness B is set to B = B _min in step 151, a process of increasing the brightness by one step is performed in step 176. The flow returns to step 152, and the processing up to the above is performed in the same manner. When the above-described processing is completed for all the luminances, the grouping processing ends.

FIG. 6 shows the details of the group update process shown in step 156 of FIG.
6a, while incrementing the number n of groups,
A flag is displayed to indicate that group number n is valid.
Set FLG (n) = 1. Flag FLG (n) is group number n
Is a variable indicating whether or not it is valid. When it is 1, it is valid, and when it is 0, it is invalid. The reason why the variable FLG is necessary is a countermeasure when two groups are united while scanning X and Y in the grouping subroutine shown in FIG. This specific example is described in FIG.
The subroutine and the group number correction subroutine of FIG. 10 will be described.

In step 156b, a process of substituting the group number n into a variable N (x, y) representing which group the pixel at address x, y belongs to, and the number of elements of the group n, that is, belonging to the group of group number n A process K (n) for substituting the number of elements to be performed is performed. Here, since the group has just been formed, the number of elements is 1, and K (n) = 1 is set. This ends the group update processing.

FIG. 7 shows the details of the processing of the group determination 1 shown in step 159 of FIG.
At 59a, the luminance value B (x,
It is determined whether or not y) is the same as the luminance B {(x−1), y} of the pixel to the left of a certain pixel. If so, step 159b
Substituting the group number N {(x-1), y} of the pixel to the left of that into the group number N (x, y) to which the light receiving element belongs, and the number of elements belonging to the group with the group number n Increment K {N (x, y)}. If not, the group update process shown in step 156 (the process shown in FIG. 6) is performed.

FIG. 8 shows the details of the processing of the group discrimination 2 shown in step 168 of FIG.
In 68a, the brightness value B (x,
It is determined whether or not y) is the same as the luminance B {x, (y-1)} of a pixel immediately below a certain pixel. If so, step 168b
Substituting the group number N {x, (y-1)} of the next lower pixel into the group number N (x, y) to which the light receiving element belongs, and the number of elements belonging to the group with the group number n Increment K {N (x, y)}. If not, the group update process shown in step 156 (the process shown in FIG. 6) is performed.

FIG. 9 shows the details of the processing of the group determination 3 shown in step 169 of FIG. Step 1
In 69a, the brightness value B (x,
It is determined whether or not y) is the same as the luminance B {(x−1), y} of the pixel to the left of a certain pixel. Otherwise, step 169
b), and if so, step 169d.
Is performed.

In step 169b, it is determined whether or not the brightness is the same as the brightness B {x, (y-1)} of the pixel immediately below the certain pixel. If not, the group update processing shown in step 156 (the processing shown in FIG. 6) is performed, and if so, in step 169c, the group number N (x,
y) is substituted with the group number N {x, (y-1)} of the immediately lower pixel, and the number K {N of elements belonging to the group of group number n
(x, y)}.

In step 169d, it is determined whether or not the luminance is the same as the luminance B {x, (y-1)} of the pixel immediately below the certain pixel. Otherwise, in step 169q, the group number N {(x-1), y} of the pixel to the left of the light receiving element is substituted for the group number N (x, y) to which the light receiving element belongs, and the group number The number K {N (x, y)} of elements belonging to the group n is incremented. If so, the processing of step 169e is performed.

In step 169e, it is determined whether or not the group number of the address (x-1, y) is the same as the group number of the address (x, y-1). If so, the processing in step 169q described above is performed; otherwise, the processing in step 169f is performed.

In step 169f, it is determined which of the group number of the address (x-1, y) and the group number of the address (x, y-1) is larger. In this case, the addresses (x-1, y) and (x, y-1) are combined into the same group, so the group numbers are unified to the smaller number.

This is for the following reason. For example, even if there is a subject as shown in FIG. 10, the grouping subroutine scans in the x-axis direction from x = 1, y = 1 to perform grouping. Therefore, when x = 5 and y = 5, the number of groups is incremented as subjects having different luminances. Then, when y = 5 and x = 9 are reached, a subject having a different luminance is again encountered, and the number of groups is incremented. However, the subject of y = 5, x = 5 and the subject of y = 5, x = 9 are the same (connected at the upper side). But it is y =
Since it can be understood only when 9, x = 9, it has been counted as a different subject until then. For this reason, when y = 9 and x = 9, the groups are united and the group number and the like are corrected.

If N {(x−1), y} is smaller than N {x, (y−1)} in step 169f, N is substituted in step 169g and K is incremented. In step 169h, 0 is substituted for the group valid flag FLG (x, y-1) at the address (x, y-1), and in step 169i, the invalid group number is passed to a group number correction subroutine described later. Substitute the group number that will be merged and disappear with KN, and substitute the group number after merging with the effective group number RN in the variable passed to the group number correction subroutine. Then, a group number correction subroutine shown in step 169n is executed.

If N {(x-1), y} is larger than N {x, (y-1)} in step 169f, the processing of steps 169j to 169m is performed, and then the group number correction of step 169n is performed. A subroutine is executed, but these processes are different from the processes of steps 169g to 169i only in the variables of x and y, and the details of the processes are the same, so that the description will be omitted.

FIG. 11 shows the details of the group number correction subroutine shown in step 169n of FIG. In step 169n1, the number of elements K (n) of the group is obtained by adding the groups to be combined (here, the number RN that is added and remaining is represented as K (RN) because the variable n is the variable n). The elements of the missing group are cleared to 0 just in case.

Step 169n2 is a process for setting the coordinates Kx and Ky used only in this subroutine to the initial value 1. Then, as shown in step 169n3, (Kx, K
y) The pixel at the address is KN (the group number of the one that merges and disappears)
Is determined. If so, in step 169n4, the group number is rewritten to RN (the group number that remains after combining). If not, the process of step 169n4 is skipped.

Step 169n5 determines whether Ky has become y, and if not, step 169n6.
Is performed, and if so, step 169n
9 is performed.

In step 169n6, it is determined whether or not Kx is 19, that is, whether the operation has been performed to the rightmost end of the screen. If x = 19, Ky is incremented in step 169n8, and then Kx = 1 is set. If not, step 169
In step n7, Kx is incremented.

Step 169n9 determines whether or not Kx has advanced to X, and if not, step 169n9.
In step 10, Kx is incremented, and the process returns to step 169n3. If so, the subroutine ends.

FIG. 12 is a subroutine showing details of calculating the number gn of the effective groups in step 200 in FIG. 3, and there is n as a variable representing the number of groups. If it becomes
Since the exact number of groups cannot be determined only by the variable n, a variable gn is provided separately. Step 201 in FIG.
Is a process for setting the group number i to 1 and setting the number of valid groups gn to 0.

Step 202 determines whether or not FLG (i) = 1.
That is, it is determined whether or not the group number i is valid. If the group number i is valid, gn is incremented in step 203, and if not, step 203 is skipped. In step 204, i = n, that is, it is determined whether or not the group number i has reached the end. Otherwise, i is incremented in step 205 and the process returns to step 202. If so, this subroutine is executed. finish.

FIG. 13 shows the details of the subroutine for calculating the barycentric positions S _x (i) and S _y (i) for each group shown in step 250 of FIG. First, in step 251, i = 1 is set. In step 252, it is determined whether FLG (i) is 1, that is, whether or not the group number i is valid. If it is valid, x = 1, as shown in step 253, y = 1, x _add = 0, y _add = 0 are set, and the process of step 254 is performed.

In step 254, it is determined whether or not the group number of the pixel at the address (x, y) is i. If so, the process in step 255 is performed. If not, step 256 is performed. Skip to. Step 255 is x
_add, a process for adding x, y to y _{the add.} If x = 19 in step 256, y = 13 in step 258
Is determined, and if not, x is incremented in step 257 and the process returns to step 254.

If y = 13 in step 258, x = 1 is set in step 259, y is incremented, and the process returns to step 254. If so, as shown in step 260, the position of the center of gravity of the i-th group is determined. Coordinates S _x (i), S
_y (i) is obtained, and it is determined in step 261 whether i = n.

If i = n is not satisfied in step 261, i is incremented in step 262, and the process returns to step 252. If i = n, the processing of this subroutine ends.

FIG. 14 shows the details of the subroutine for calculating the luminance BVG (i) for each group shown in step 300 of FIG. First, in step 301, i = 1 is set. In step 302, it is determined whether or not FLG (i) is 1, that is, whether or not the group number i is valid.
As shown at 03, x = 1, y = 1, and BV _add = 0 are set, and the process of step 304 is performed.

In step 304, it is determined whether or not the group number of the pixel at the address (x, y) is i. If so, the processing in step 305 is performed. If not, step 306 is performed. Skip to. Step 305 is BV
_This is the process of adding BV (x, y) to add. And step 3
If x = 19 in 06, it is determined whether or not y = 13 in step 308. If not, x is incremented in step 307 and the process returns to step 304.

If y is not 13 in step 308, x = 1 is set in step 309, y is incremented, and the process returns to step 304. If so, as shown in step 310, the position of the center of gravity of the i-th group is determined. Coordinates S _x (i), S
_y (i) is obtained, and it is determined in step 311 whether i = n.

If i = n is not satisfied in step 311, i is incremented in step 312 and the process returns to step 302. If i = n, the processing of this subroutine ends.

FIG. 15 shows the exposure calculation subroutine 35 of FIG.
0 is the detailed content. First, in step 351, if the number of effective groups gn is 1, in step 352 the exposure value BVa
As BVG (1). If the number of effective groups gn is not 1, i is set in step 353, j and BV _add are reset, and the processing in step 354 is performed. Note that i is the number of groups (the number of loops), and j is the number of groups that have contributed to the exposure calculation.

At step 354, it is determined whether FLG (i) = 1, that is, whether the i-th group is valid. If it is valid, the process at step 355 is performed. If not, the process skips to step 358. Step 355 is S _y (i)
Is the maximum value of {S _y (1)... S _y (n)}, that is,
It is determined whether or not the position of the center of gravity of S _y (i) is at the top of the screen.

If it is at the top, BVG (i) will be {BVG (i)
.., BVG (n)}, and if so, the process of step 358 is performed as it is, and
If not, the process of step 357 is performed. In step 357, j is incremented and BVG is added to BV _add .
(B) is the new BV _add .

In step 358, it is determined whether or not i has become n. If not, in step 359, i is incremented and the process returns to step 354. If so, in step 360, the exposure value BVa is obtained. In this case, as can be seen in steps 355 and 356, the group having the highest position of the center of gravity of the group and giving the maximum luminance is regarded as a background such as the sky, and is excluded from the calculation of the exposure value.

As a result, when the photometry of the subject as shown in FIG. 2A is performed, as shown in FIG.
The subject is divided into three groups, ie, groups 2 and 3, the background is excluded, and photometric calculation is performed only on the subject.

[0052]

As described above, according to the present invention, in a photometric operation device for calculating an optimum exposure value of a photographing object, an object scene is divided into a plurality of regions, and photometry is performed for each region, and the photometric output value is calculated. Since the photometric areas are compared and the areas of similar luminance are processed in the same group in comparison, the shape of the photometric areas to be grouped is different from the conventional one, This has the effect that an accurate luminance distribution can be measured regardless of the shape of the subject.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of the apparatus of the present invention.

FIG. 2 is a diagram showing an example of a subject and a luminance distribution on a screen.

FIG. 3 is a general flowchart showing the operation of the apparatus of FIG. 1;

FIG. 4 is a flowchart of a subroutine showing details of B (x, y) substitution (a value obtained by rounding off a brightness value BV and converting it into an integer) shown in step 100 of FIG. 3;

FIG. 5 is a flowchart of a subroutine showing details of grouping shown in step 150 of FIG. 3;

FIG. 6 is a flowchart of a subroutine showing details of group update shown in step 156 of FIG. 5;

FIG. 7 is a flowchart of a subroutine showing details of group determination 1 shown in step 159 of FIG. 5;

FIG. 8 is a flowchart of a subroutine showing details of group determination 2 shown in step 168 of FIG. 5;

FIG. 9 is a flowchart of a subroutine showing details of group determination 3 shown in step 169 of FIG. 5;

FIG. 10 is a diagram for explaining the reason for performing group number correction;

FIG. 11 is a flowchart of a subroutine showing details of group number correction shown in step 169n of FIG. 5;

FIG. 12 is a flowchart of a subroutine showing details of a group number gn calculation shown in step 200 of FIG. 3;

FIG. 13 is a flowchart of a subroutine showing details of calculation of centroids S _x and S _{y for} each group shown in step 250 of FIG. 3;

FIG. 14 is a flowchart of a subroutine showing details of luminance calculation for each group shown in step 300 of FIG. 3;

FIG. 15 is a flowchart of a subroutine showing details of exposure calculation shown in step 350 of FIG. 3;

FIG. 16 is a diagram for explaining a conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Main mirror 3 Screen 4 Penta prism 5 Light receiving element 6 Photometric circuit 6 8 Number of groups calculation means 9 Group brightness calculation means 10 Center of gravity position calculation means 11 Exposure calculation means 12 Exposure control means 13 Shutter 14 Aperture

Claims (2)

(57) [Claims] 1. A photometric operation device for calculating an optimal exposure value of a photographing object, a photometric unit for dividing an object scene into a plurality of regions and transmitting a photometric output for each region, and an output value of the photometric unit. And a photometric area grouping means for processing areas in which photometric areas are adjacent to each other and have similar luminance as the same group. 2. A photometric operation device for calculating an optimum exposure value of an object to be photographed, comprising: a photometric means for dividing an object scene into a plurality of areas and transmitting a photometric output for each area; and an output value of the photometric means. A photometric region grouping unit that compares the photometric regions adjacent to each other and processes regions of similar luminance as the same group, and a group number calculating unit that calculates the number of groups grouped by the grouping unit, Group luminance calculating means for calculating an average luminance value in a group, centroid calculating means for calculating a centroid in a region for each group, and exposure calculating means for calculating an optimal exposure value from a photometric value at the position of the determined centroid. A photometric computing device.