JPH04257831A - Photometric calculation device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 the optimum exposure value of a camera.

0002

2. Description of the Related Art Conventionally, as a method of obtaining photometric values within a photographic screen, the frames within the photographic screen are sequentially made smaller as shown in FIG. The photometric value was determined by calculating the average of the photometric values within the range.

0003

[Problems to be Solved by the Invention] However, in such conventional devices, photometry is performed using a reduced photometry frame that simply reduces the size of the photometry screen, so the shape of the photometry area to be grouped is not determined from the beginning. Therefore, there was a problem in that it was not possible to measure the accurate brightness distribution of the subject. This device is designed to reliably measure the brightness of each subject even when there are multiple subjects.

0004

[Means for Solving the Problems] In order to solve such problems, a first invention provides a photometry means for dividing a field into a plurality of regions and transmitting a photometry output for each region, and a photometry means for dividing a field into a plurality of regions and transmitting a photometry output for each region. The photometric area grouping means compares the output values of the means and processes areas in which the photometric areas are adjacent and have similar luminance as the same group.

[0005] The second invention includes a photometric means that divides the field into a plurality of areas and sends a photometric output for each area, and compares the output values of the photometric means to determine whether the photometric areas are adjacent. photometric area grouping means for processing areas with similar brightness as the same group; group number calculation means for calculating the number of groups grouped by the grouping means; and calculating an average brightness value within the group. The apparatus is equipped with a group brightness calculation means, a center of gravity calculation means for calculating the center of gravity in the area of each group, and an exposure calculation means for calculating the optimum exposure value from the photometric value at the determined position of the center of gravity.

[0006]

[Operation] Portions of the subject that have similar brightness and are close to each other are divided into blocks, and photometry is performed for each block. For this reason, the photometry value is known for each block, and if it is determined that the object with a high center of gravity and brightness is the sky, the photometry will not be carried out in the direction of brightness.

[0007]

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention, in which 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. Ru. The information detected by the light-receiving element 5 is supplied to a photometry circuit 6, a group number calculation means 8, a group brightness calculation means 9, and a center of gravity position calculation means 10, where predetermined processing is performed on each of them, and the information is supplied to an exposure calculation means 11 to determine the optimum value. The exposure amount is calculated, and the shutter 13 is controlled via the exposure control means 12.
and controls the aperture 14.

When photographing a subject as shown in FIG. 2(a), this device focuses the image on the surface of the light-receiving element 5, which is composed of a plurality of matrices, as shown in FIG. The part is treated as one group, the brightness of each group is measured, and the exposure amount is determined. In this case, the symbol 20 is treated as group 1, the symbol 21 as group 2, and the symbol 22 as group 3. Since group 1 is bright and located at a high position, it is determined that it is empty and is usually excluded from the exposure target. The dark thing at the bottom is a person. Normally, we often photograph objects at the bottom of the screen, so it is best to determine the exposure amount according to the object at the bottom in this way.

The circuit shown in FIG. 1 is a circuit for performing such processing, and the photometry circuit 6 measures the absolute value luminance (B) of the received light.
The circuit for measuring the V value) and the grouping means 7 are shown in FIG. 2(b).
A group number calculating means 8 is a means for counting the number of groups, and a group brightness calculating means 9 is a means for grouping together parts of adjacent cells having similar brightness among a plurality of light receiving cells shown in FIG. The means for measuring the luminance of the group and the center of gravity position calculation means 10 are means for calculating the center of gravity position of each group.

The operation of this device will be explained below using flowcharts. Since many variables appear in each flowchart, the variables will be defined below. (a) x, y... Variables indicating the address of the light receiving element. In Fig. 2(b), x has a value from 0 to 19, and y has a value from 0 to 1.
Takes values up to 3. (b) BV (x, y)...Brightness value output by 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 (e)n...Value representing the number of groups incremented in the group update subroutine (f)gn...Group that became invalid from n minus the number (total number of valid groups) (g) Bmin... Minimum value of B (x, y) (ch) B
max... Maximum value (li) of B(x, y) FLG(n
)...is a flag, and if the nth group is valid, "
1", if invalid, take 0 (nu) K(n)...Number of elements belonging to the group with group number n (ru) KN...Variable passed to the group number correction subroutine. Invalid group number (W) RN... Valid group number (W) Sx (i) in the variable passed to the group number correction subroutine... Coordinates of the center of gravity of the group in the group with group number i (x) (f) Sy(i)...Coordinate of the center of gravity of the group in the group with group number i (y) (y) BVG(i)...Average brightness value in the group with group number i (location in group i) BV(x,y)
average value)

FIG. 3 is a flowchart showing the operation of the main routine of this device. In step 80, a process of setting n=0 is performed, and in step 100, B(
x, y) substitution subroutine, grouping subroutine in step 150, group number gn calculation subroutine in step 200, centroid (S
x, Sy) calculation, brightness calculation for each group in step 300, and exposure calculation in step 350 are performed in this subroutine, and then exposure control is performed in step 81. Details of each subroutine will be described later.

FIG. 4 shows B(x
, y) is a flowchart for explaining the substitution subroutine, and this process is performed by calculating the brightness value BV(
The integer luminance value B(x, y) is rounded to an integer.
, y), and its maximum and minimum values. This process sets x=1, y=1 in step 101, and in step 102, the integer luminance value is set to B(x, y
)=Int{BV(x,y)+0.5}. The process in step 102 involves rounding off the brightness output value BV (x, y) of the light receiving element at the x, y coordinates, and then
It is converted into an integer. Next, in step 102, the value of x is incremented in step 104 until it is determined in step 103 that x has reached 19, which is the maximum value of the x coordinate in this embodiment. x,
Find y).

[0013] When all the integer luminance values in the x direction have been determined, a decision is made in step 105, but at this point, the y
= 1, the coordinate in the y direction is incremented by one in step 106, and the coordinate is incremented by 1 from step 102 again.
04 is performed to obtain the integer luminance value of the x coordinate at the y coordinate. If this process is repeated, it will eventually be determined in step 105 that y>13, so step 1
In 07, the integer luminance value B(x, y) obtained so far
The maximum values of Bmax and Bmin are determined, and the B(x,y) assignment subroutine in step 100 of FIG. 3 is completed.

FIG. 5 shows a subroutine for realizing the grouping of step 150 in FIG. First, in step 151, a determination brightness value B, which is a criterion for determination, is determined.
is set to Bmin determined in step 107 of FIG. 4, and x=1, y=1 are set in step 152. Then, in step 153, it is determined whether the brightness value B (x.y) output by the light receiving element at this coordinate is equal to the determination reference value B set in step 151. The criterion value at this point is set to the lowest luminance value output by the light-receiving element measured earlier, so the probability of matching is low at this stage, but for ease of understanding, it is assumed that they match. Let's proceed with the explanation.

[0015] In step 153, B(x, y) is
, here, if it is equal to Bmin set in step 151, it is determined in step 154 whether y=1, and since y=1 at this point, x is set in step 155.
It is determined whether x = 1, but since x = 1,
In this case, the group update subroutine process of step 156 is performed (details of this process will be described later, but if x=1, that is, this process is performed only at the lower left corner of the screen). Then, in step 157, it is determined that x>19 is not satisfied, so the x coordinate is incremented in step 158, and the flow continues to step 15.
Return to 3.

Here, in step 153, B(x, y
)=B, that is, it is assumed that Bmin 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 is not 1, and the process of group determination 1 in step 159 is performed (details of this process will be described later, but this process is only performed at the bottom edge of the screen).

After this, step 157, 1 is performed in the same manner as described above.
After the x coordinate is incremented by 58,
The flow returns to step 153 and the same processing as described above is performed, so that it is eventually determined in step 157 that x>19. However, in step 165 y>13
Since it is determined that x=
1, y=y+1 processing is performed, and the flow goes to step 15.
Return to 3.

At this stage, in step 154, y=
1, and in step 167 it is determined that x=1, so the process of group determination 2 in step 168 is performed (
This process will be described later, but it is a process for the left edge of the screen excluding the lower left edge). Thereafter, in step 157, x
Since the process of increasing the x coordinate is performed in step 158 until the determination of >19 is made, step 167 then
It is determined that it is not 1, and the group determination 3 in step 169 is performed.
(This process will be explained later, but the left edge of the screen,
(This is processing of the area excluding the bottom edge).

Thereafter, while repeating the increase in the x coordinate in step 158 and the increase in the y coordinate in step 166, group determination 2 in step 168 and group determination 3 in step 169 are performed, and when y exceeds 13, At this point, it is determined in step 175 whether B=Bmax, but the brightness B is determined in step 151 as B=Bmax.
Since the brightness is set to min, the brightness is set to 1 in step 176.
Step increment processing is performed, and the flow proceeds to step 152.
The process returns to , and the processes described above are performed in the same way. When the above-described processing is completed for all luminances, the grouping processing is ended.

FIG. 6 shows the details of the group update process shown in step 156 of FIG.
In step 6a, the number of groups n is incremented, and
In order to indicate that group number n is valid, the flag FLG(n) is set to 1. Flag FLG(n) is a variable indicating whether group number n is valid or not, and is 1
If , it is valid, and if it is 0, it is invalid. Variable FL
The reason why G is necessary is to prevent two groups from merging while scanning X and Y in the grouping subroutine shown in FIG. 5. For this specific example, see Figure 9.
This will be explained in the group determination 3 subroutine in FIG. 10 and the group number correction subroutine in FIG.

Step 156b includes a process of assigning a group number n to a variable N(x,y) representing which group the pixel at address x, y belongs to, and determining the number of elements in group n, that is, the group belonging to group number n. A process K(n) of substituting the number of elements is performed. Here, since the group has just been created, the number of elements is 1, and K(n)=
Set to 1. This completes the group update process.

FIG. 7 shows the details of the group determination 1 process shown in step 159 of FIG.
Brightness value B obtained by rounding the brightness value BV to a positive number in step 59a
The brightness of the pixel to the left of a pixel (x, y) is B{(x-
1), y}. If so, in step 159b, the group number N(x,y) of the pixel to the left of the group number N(x,y) to which the light receiving element belongs is set.
(x-1), y} is substituted, and the number of elements K{N(x, y)} belonging to the group with group number n is incremented. 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 group determination 2 process shown in step 168 of FIG.
Brightness value B obtained by rounding the brightness value BV to a positive number in step 68a
The brightness of the pixel one below the pixel (x, y) is B{x, (
y-1)}. If so, in step 168b, the group number N(x, y) to which the light receiving element belongs is set to the group number N of the pixel immediately below it.
x, (y-1)}, and the number of elements K{N(x, y)} belonging to the group with group number n is incremented. 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 group determination 3 process shown in step 169 of FIG. Step 1
Brightness value B obtained by rounding the brightness value BV to a positive number in step 69a
The brightness of the pixel to the left of a pixel (x, y) is B{(x-
1), y}. If not, the process of step 169b is performed, and if that is the case, the process of step 169d is performed.

In step 169b, it is determined whether the brightness of a certain pixel is the same as the brightness B{x, (y-1)} of the pixel immediately below it. If not, the group update process shown in step 156 (the process shown in FIG. 6) is performed, and if so, in step 169c, the group number N(x, y) to which the light receiving element belongs is updated. The group number N{x, (y-1)} of the next pixel below is assigned, and the number of elements K{N(x, y)} belonging to the group with the group number n is incremented.

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

Step 169e determines whether the group number at address (x-1, y) and the group number at address (x, y-1) are the same. If so, the process of step 169q described above is performed, and if not, the process of step 169f is performed.

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

[0029] This is due to 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 and groups them. Therefore, when x=5 and y=5 are reached, the number of groups is incremented as subjects with different brightness. Then, when y=5 and x=9 are reached, an object with different brightness is encountered again, and the group number is incremented again. However, the subject at y=5, x=5 and the subject at y=5, x=9 are the same (connected at the top). However, this is only noticeable when y=9 and x=9, so until then it is counted as a different subject. Therefore, when y=9 and x=9 are reached, the groups are combined and the group number etc. are corrected.

In step 169f, N{(x−1
), y} is smaller than N{x, (y-1)}, N is substituted and K is incremented in step 169g. Then, in step 169h (x, y
-1) Address group valid flag FLG (x, y-1)
In step 169i, the group number that merges and disappears with the invalid group number KN is assigned to the variable passed to the group number correction subroutine to be described later, and the variable passed to the group number correction subroutine is substituted. After combining, the group number is assigned to the valid group number RN. Then, the group number correction subroutine shown in step 169n is executed.

In step 169f, N{(x-1)
, y} is larger than N{x, (y-1)}, after steps 169j to 169m are performed, the group number correction subroutine of step 169n is executed; From 169
The only difference between the processing of i and the variables of x and y is that the processing contents are the same, so a description thereof will be omitted.

FIG. 11 shows the details of the group number correction subroutine shown in step 169n in FIG. Step 169n1 calculates the number of elements K(n) of the group by adding together the groups to be combined (here, the number RN remaining after addition is the variable n, so K(RN
). The elements of the group that will disappear are cleared to 0 just in case.

Step 169n2 is a process of setting the coordinates Kx and Ky used only in this subroutine to an initial value of 1, and then as shown in step 169n3 (
It is determined whether the pixel at the address (Kx, Ky) is KN (the group number that will disappear when combined). If so, in step 169n4, the group number is rewritten to RN (the group number of the group that remains after the combination). If not, the process of step 169n4 is skipped.

Step 169n5 determines whether Ky has become y, and if not, step 169n5
6, and if yes, step 169
Perform the process shown in n9.

In step 169n6, it is determined whether Kx has reached 19, that is, has reached the rightmost end of the screen. x=
In the case of 19, Ky is incremented in step 169n8 and Kx is set to 1; otherwise, Kx is incremented in step 169n7.

Step 169n9 determines whether Kx has progressed to X, and if not, step 16
Increment Kx at 9n10 and step 169n
Return to step 3, and if so, end this subroutine.

FIG. 12 is a subroutine showing the details of calculating the effective number of groups gn in step 200 in FIG. In this case, the exact number of groups cannot be determined from the variable n alone, so
A separate variable gn is provided. Step 2 in Figure 12
01 is a process of setting the group number i to 1 and setting the number of valid groups gn to 0.

Step 202 determines whether FLG(i)=1, that is, whether group number i is valid. If it is valid, step 203 increments gn; if not, gn is incremented. is step 203
Skip. Step 204 determines whether i=n, that is, group number i has reached the end. If not, increment i in step 205 and return to step 202. If so, this subroutine is executed. finish.

FIG. 13 shows the detailed contents of the subroutine shown in step 250 in FIG. 3 for determining the center of gravity positions Sx(i) and Sy(i) for each group. First, in step 251, i=1 is set, and in step 252, it is determined whether FLG(i) is 1, that is, group number i is valid. If it is valid, x=1 as shown in step 253.
, y=1, xadd=0, yadd=0, and the process of step 254 is performed.

Step 254 determines whether the group number of the pixel at address (x, y) is i, and if so, the process of step 255 is performed; otherwise, the process of step 256 is performed. Skip to. Step 255
is a process of adding x and y to xadd and yadd. Then, when x=19 in step 256, it is determined whether y=13 in step 258,
If not, x is incremented in step 257 and the process returns to step 254.

If y=13 in step 258, set x=1 in step 259, increment y, and return to step 254; if so, step 2
As shown in 60, the center of gravity position coordinate S of the i-th group
x(i) and Sy(i) are determined, and it is determined in step 261 whether or not i=n.

If i=n is not true in step 261, i is incremented in step 262 and the process returns to step 252, and if i=n, the process of this subroutine is ended.

FIG. 14 shows the detailed contents of the subroutine for determining the brightness BVG(i) for each group shown in step 300 of FIG. First, in step 301, i=1 is set, and in step 302, it is determined whether FLG(i) is 1, that is, group number i is valid. If it is valid, x=1, as shown in step 303. y=1, BV
Set add=0 and perform the process of step 304.

In step 304, it is determined whether the group number of the pixel at address (x, y) is i, and if so, the process of step 305 is performed, and if not, the process of step 306 is performed. Skip to. Step 305
is a process of adding BV(x,y) to BVadd. Then, when x=19 in step 306, it is determined whether y=13 in step 308,
If not, x is incremented in step 307 and the process returns to step 304.

If y=13 in step 308, set x=1 in step 309, increment y, and return to step 304; if so, step 3
As shown in 10, the center of gravity position coordinate S of the i-th group
x(i) and Sy(i) are obtained, and it is determined in step 311 whether or not i=n.

If i=n is not true in step 311, i is incremented in step 312 and the process returns to step 302, and if i=n, the process of this subroutine is ended.

FIG. 15 shows the exposure calculation subroutine 35 of FIG.
This is the detailed content of 0. First, if the number of effective groups gn is 1 in step 351, the exposure value B is determined in step 352.
BVG (1) is given as Va. Effective number of groups gn
If is not 1, set i in step 353,
j, BVadd is reset, and the process of step 354 is performed. Note that i is the number of groups (number of loops), and j is the number of groups contributing to the exposure calculation.

In step 354, it is determined whether FLG(i)=1, that is, the i-th group is valid. If it is valid, the process of step 355 is performed, and if it is not valid, it is skipped to step 358. Step 355
determines whether Sy(i) is the maximum value of {Sy(1)...Sy(n)}, that is, whether the center of gravity of Sy(i) is at the top of the screen.

[0049] If it is the top, then BVG(i) becomes {B
VG(i)...BVG(n)}, and if so, proceed directly to step 3.
Step 58 is performed, and if not, step 357 is performed. In step 357, j is incremented and BVadd plus BVG(i) is set as a new BVadd.

In step 358, it is determined whether or not i has become n. If not, i is incremented in step 359, and the process returns to step 354. If so, the exposure value BVa is determined in step 360. In this case, as can be seen in steps 355 and 356, the group whose center of gravity is at the top and which provides the maximum brightness is considered to be the background such as the sky and is excluded from the exposure value calculation.

As a result, when the subject shown in FIG. 2(a) is photometered, it is divided into three groups: group 1, which is the background, and groups 2 and 3, which are the objects, as shown in FIG. 2(b), and the background is are excluded, and photometry calculations are performed only on the subject.

[0052]

As explained above, the present invention provides a photometric calculation device that calculates the optimal exposure value of a photographic subject, which divides the photographic field into a plurality of areas, measures the light for each area, and calculates the photometric output value. In comparison, areas with adjacent photometric areas and similar brightness are processed as the same group, unlike conventional methods where the shape of the photometric areas to be grouped is determined from the beginning. This has the effect that accurate brightness distribution can be photometered regardless of the shape of the object.

[Brief explanation of the drawing]

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

[Figure 2]
Diagram showing an example of a subject and the brightness distribution on the screen

[Figure 3] General flowchart showing the operation of the device in Figure 1

4 is a flowchart of a subroutine showing details of B(x,y) assignment (a value obtained by rounding off the brightness value BV to an integer) shown in step 100 of FIG. 3; FIG.

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;

[Figure 8] Step 16 in Figure 5
Flowchart of a subroutine showing details of group determination 2 shown in 8.

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

[Figure 10] Diagram for explaining the reason for group number correction

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

[Figure 1
2] Flowchart of a subroutine showing details of calculating the number of groups gn shown in step 200 of FIG. 3

13] Center of gravity Sx, Sy for each group shown in step 250 of FIG. 3
Subroutine flowchart showing calculation details

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

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

[Figure 16] Diagram for explaining conventional problems

[Explanation of symbols]

1 Objective lens 2 Main mirror 3 Screen 4 Pentaprism 5 Photo receiving element 6 Photometry circuit 6 8 Group number 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)

[Claims] Claim 1: A photometric calculation device that calculates the optimal exposure value of a photographic subject, comprising a photometric means that divides a field into a plurality of regions and sends out a photometric output for each region, and an output value of the photometric means. 1. A photometric calculation device comprising photometric area grouping means for comparing and processing areas with adjacent photometric areas and similar brightness as the same group. 2. A photometric calculation device that calculates the optimum exposure value of a photographic subject, comprising: a photometry means that divides a field into a plurality of areas and sends out a photometry output for each area; photometric area grouping means for comparing and processing areas with adjacent photometric areas and similar brightness as the same group; group number calculation means for calculating the number of groups grouped by the grouping means;
A group brightness calculation means for calculating an average brightness value within a group, a center of gravity calculation means for calculating the center of gravity in each group area, and an exposure calculation means for calculating an optimum exposure value from a photometric value at the determined position of the center of gravity. A photometric calculation device characterized by: