JPH04251230A - Exposure computing device of camera - Google Patents

Abstract

PURPOSE:To provide the exposure computing means of a camera which can photograph a black subject black and a white subject white regardless of the distances of the subjects. CONSTITUTION:This device has photometric means 6, 7 which make photometry of plural regions in the subject field and respectively output the photometric signals contg. the information associated with the colors of the subjects positioned in the respective regions, a 1st discriminating means 12 for discriminating whether the subjects in the respective regions are chromatic or colorless in accordance with the photometric signals, a 2nd discriminating means 13 for discriminating whether the white or black subject exists in the prescribed colorless region or not in accordance with the photometric signal corresponding to the colorless region discriminated to be colorless and the photometric signal corresponding to the chromatic region discriminated to be chromatic, and exposure value computing means 11, 14 which compute the exposure values from the photometric signals according to the results of the discrimination of the 1st and 2nd discriminating means 12, 13.

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 for a camera that can obtain accurate exposure for black or white objects.

0002

2. Description of the Related Art Generally, exposure calculations in conventional automatic exposure cameras are performed on the assumption that the light reflectance of the subject is approximately constant. Specifically, exposure calculation is performed on the assumption that the reflectance is around 18%, which is the geometric mean of the highest reflectance of 90% and the lowest reflectance of 3% seen in general subjects. For this reason, conventional cameras have the disadvantage that both white and black subjects appear gray.

[0003] In order to eliminate such inconveniences, a camera disclosed in, for example, Japanese Patent Application Laid-Open No. 63-256934 is known. This device is equipped with a projector that emits light towards the subject and a receiver that receives the reflected light from the subject.The intensity of the reflected light from the subject is detected from the output of the receiver, and the intensity is calculated based on the distance to the subject. Based on this, the level of reflectance of the subject is determined, and the exposure value is calculated based on the determination result. In other words, if the reflectance of the subject is high, it is determined that the subject is white and the exposure value is set to a higher value than usual; conversely, if the reflectance is high, the subject is determined to be black and the exposure value is set to an undervalue. side. This allows black objects to appear black and white objects to appear white.

0004

[Problem to be Solved by the Invention] However, when the subject is located far away, such as in landscape photography, the light from the projector is not reflected and is not received by the receiver, so it is difficult to calculate the reflectance of the subject. I can't. In other words, with the above-mentioned conventional camera, when the subject distance is far, it is not possible to distinguish between black and white subjects, and black or white subjects may appear gray.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exposure calculation device for a camera that can make a black subject appear black and a white subject appear white regardless of the distance to the subject.

[0006]

[Means for Solving the Problems] To explain with reference to FIG. 1 showing one embodiment, an exposure calculation device according to the present invention measures the light of a plurality of areas in a field, and measures the light of a subject located in each area. photometric means 6, 7 each outputting a photometric signal containing information related to the color of the image; and a first determining means 12 that determines whether the subject in each area is chromatic or achromatic based on the photometric signal; Whether a white or black object exists in a predetermined achromatic area based on a photometric signal corresponding to an achromatic area determined to be an achromatic color and a photometric signal corresponding to a chromatic area determined to be a chromatic color. Second discriminating means 1 for discriminating whether
3, and exposure value calculating means 11 and 14 for calculating an exposure value from the photometric signal according to the determination results of the first and second determining means 12 and 13, thereby solving the above problem.

[0007]

[Operation] The photometering means 6 and 7 perform photometry on a plurality of areas in the field, and output photometry signals containing information related to the color of the subject located in each area. First discrimination means 1
2 determines whether the subject in each area is chromatic or achromatic based on the photometric signal, and the second determining unit 13 determines whether the subject in each area is chromatic or achromatic, and the second determining unit 13 uses a photometric signal corresponding to the achromatic area determined to be achromatic, Based on the photometric signal corresponding to the chromatic color area determined to be chromatic, it is determined whether a white or black object exists in a predetermined achromatic color area. And exposure calculation means 11,1
4 calculates an exposure value from the photometric signal according to the discrimination results of the first and second discrimination means 12 and 13. According to this, it is possible to distinguish between black and white even if the object is at an infinite distance, and if the object is black, it can be photographed as black, and if the object is white, it can be photographed as white. In the above section of means and effects for explaining the configuration of the present invention, figures of embodiments are used to make the present invention easier to understand, but the present invention is not limited to the embodiments.

[0008]

[Embodiment] - First Embodiment - A first embodiment of the present invention will be explained with reference to FIGS. 1 to 11. 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 output signal of the photometric element 6 is input to the photometric circuit 7, and the photometric circuit 7 generates three photometric signals X as described later according to the input signal.
, Y, and Z and outputs them.

Reference numeral 10 denotes a control circuit, which includes a brightness calculation unit 1 that calculates subject brightness from the photometry signal Y from the photometry circuit 7.
1, a color discrimination section 12 that discriminates whether the subject is chromatic or achromatic based on the photometric signals X, Y, and Z, and a black and white section 12 that discriminates whether the subject determined to be achromatic is black or white. Discrimination unit 13, brightness calculation unit 11, two discrimination means 12
, 13. Reference numeral 8 denotes an exposure control circuit, which drives the aperture 9 and shutter 10 based on the exposure value calculated by the exposure calculation section 14 to perform photographing.

FIG. 2 is an enlarged view of the photometric element 6. This photometric element 6 is divided into a total of 247 division elements 6A, 13 vertically and 19 horizontally, and each division element 6A corresponds to each division area obtained by similarly dividing the field into 247. As shown in FIG. 3, each dividing element 6A further includes 6a, 6b, 6
It is divided into three parts, each having wavelength characteristics x(λ), y(λ), and z(λ) as shown in FIG. 4, each of which is equipped with a filter. FIG. 4 is generally referred to as a spectral stimulus value, and represents the sensitivity distribution of three types of photoreceptor cells in the human eye. and x (λ) is red (R), y (λ)
has sensitivity to green (G), and z(λ) has sensitivity to blue-violet (B). The outputs of the divided elements 6a, 6b, and 6c equipped with filters having such sensitivity characteristics are respectively input to the photometric circuit 7, and the photometric circuit 7
- Outputs photometric signals X, Y, and Z according to the outputs of 6c.

Here, FIG. 5 is a generally known xy chromaticity diagram, and using the photometric signals X, Y, and Z, x=X
/(X+Y+Z) y=Y/(X+Y+Z)
The color can be determined by plotting (x, y) given by on this xy chromaticity diagram. The ellipse in Figure 5 is a figure drawn by the equation (y-x)2+(x-0.31)2=0.112, and its center is (x,y)=(
0.31, 0.32). This coordinate (0.31,0
．． 32) is the achromatic axis for the surface color of an object illuminated with standard light C, and when (x, y) obtained from the output of a certain dividing element 6A is (0.31, 0.32) for,
It can be said that the object in the area corresponding to the dividing element 6A is completely achromatic. In this example, the above (x
, y) is within the ellipse shown by the above formula, the chromatic color (
When it is outside the ellipse, it is considered to be an achromatic color (black and white).

[0012] Note that the formula for the ellipse is not limited to this. Further, as shown in FIG. 3, the above-mentioned dividing element 6A is 6a from the left.
, 6b, and 6c, strictly speaking, it cannot be said that 6a to 6c are photometrically measuring the same part. 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.

Next, the control procedure by the control circuit 10 will be explained with reference to flowcharts shown in FIGS. 6 to 11. FIG. 6 shows the main program, and this program is started when a release button (not shown) is pressed halfway. First, in step S1, a photometric signal is captured. That is, photometric signals X, Y, and Z based on the detection outputs of the 247 divided elements 6A described above are inputted from the photometric circuit 7, respectively. Next, in step S2, the luminance value of each area of the object scene is calculated based on Y of the input photometric signals X, Y, and Z. Details of this brightness value calculation process are shown in the subroutine of FIG. 7, and this is the control performed by the brightness calculation section 11.

In FIG. 7, first, in step S11, variables i and j are both set to 1, and then, in step S12, a photometric signal Y(i, j) is read. Here, i indicates the horizontal address of the divided photometric element 6A in FIG.
, 2, . . . , 19, and j similarly indicates the address in the vertical direction, from the bottom to the top, 1, 2, . . . , 13. That is, for example, the photometric signal Y corresponding to the lower left photometric element 6A is Y(1,1), and the photometric signal Y corresponding to the upper right photometric element 6A is Y(19,13).

Next, in step S13, the read photometric signal Y(i,j) is multiplied by a predetermined proportionality constant K to obtain a brightness value BV(i,j). That is, y(λ) mentioned above
The sensitivity characteristic is exactly the same as V(λ) (standard luminous efficiency) in photometry, and therefore, the luminance value can be determined by multiplying the photometry signal Y by a constant.

This brightness value calculation is performed while incrementing i by 1 in step S15 until i=19 is determined in step S14, that is, for one column of divided elements 6A,
If step S14 is affirmed, i=1, j is incremented by 1, and brightness value calculation is performed in the same manner for the next column of divided elements 6A. Then, when j=13 is determined in step S16, that is, when the luminance values have been calculated for all 247 divided elements 6A, the process returns to the process of FIG. 6.

Step S3 in FIG. 6 performs color discrimination processing. The details of this color discrimination process are shown in the subroutine of FIG.
This is control by the color discrimination section 12. In FIG. 8, in step S21, i and j are set to 1, and in the following steps S22 to S30, it is determined whether all the divided elements 6A are chromatic or achromatic. That is, in step S22, each photometric signal X(i,j), Y(i
, j) and Z(i, j) respectively, and step S
23, x=X/(X+Y+Z) y=Y/(X+Y
+Z) to find x and y. In step S24, it is determined whether or not the obtained x, y satisfy (y-x)2+(x-0.31)2>0.112, that is, x, y are in the xy chromaticity diagram of FIG. Determine whether it is included inside the indicated ellipse or on the line. If step S24 is affirmed, it is determined that the subject in the area corresponding to the dividing element 6A is achromatic, and step S26
The flag FLGW (i, j) is set to "1" in step S25, and if the result is negative, it is determined that the subject in the area corresponding to the dividing element 6A is chromatic, and the flag FLGW (i, j) is set to "0" in step S25. The process advances to step S27. Then, when FLGW (i, j) is set for all the divided elements 6A, FIG.
Return to processing. Here, if the subject in the area is achromatic, the area is called an achromatic area, and if the subject in the area is chromatic, the area is called a chromatic area.

In step S4 of FIG. 6, black and white discrimination processing is performed. The details of this process are shown in the subroutines of FIGS. 9 and 10, and this is the control performed by the black and white discriminator 13. In FIG. 9, in step S31, i=1, j=1
In step S32, Wmax=0, Wmin=
20, Cmax=0, Cmin=20. Here, Wmax is the maximum brightness (BV) of the achromatic color area, Wm
in represents the minimum brightness of the achromatic color area, Cmax represents the maximum brightness of the chromatic color area, and Cmin represents the minimum brightness of the chromatic color area. In step S33, it is determined whether the flag FLGW (i, j) set for each divided element 6A is 1 or 0, and if it is 1 (in the case of an achromatic area), step S35 is performed.
So, Wmax=Max(Wmax, BV(i,j))Wmi
Perform n=Min(Wmin, BV(i,j)) and if flag FLGW(i,j) is 0 (in case of chromatic color area)
In step S34, Cmax=Max(Cmax, BV(i,j))Cmi
Perform n=Min(Cmin, BV(i,j)). Here, Max (A, B) is the maximum value of A, B, Mi
n(A, B) indicates the minimum value of A and B, respectively. The process of step S34 or S35 is performed on all the divided elements 6A in steps S33 to S39,
This determines Wmax, Wmin, Cmax, and Cmin.

Next, the process proceeds to step S40 in FIG. 10, where it is determined whether all flags FLGW are 1. If affirmative, it is determined that the entire field is achromatic, and 1 is set to the variable WH in step S42. , assign 1 to the variable BL, respectively. Here, in this embodiment, as will be described in detail later, a black or white object is discriminated using object brightness in a chromatic color area, but as described above, when the entire object field is achromatic, Since this cannot be determined, WH=1 and BL=1 are assumed to unconditionally assume that both black and white objects exist.

If step S40 is negative, it is determined in step S41 whether all flags FLGW are 0 or not, and if affirmative, it is determined that the entire scene is chromatic, and variable WH is set in step S43. Assign 0 to , and 0 to variable BL. After steps S42 and S43, the process returns to the process of FIG. 6.

Furthermore, if step S41 is negative,
That is, if there are chromatic areas and achromatic areas in the scene, the process proceeds to step S44, and it is determined whether the maximum luminances Wmax and Cmax obtained above satisfy the relationship Wmax>Cmax. If step S44 is affirmed, it is determined that a white object exists in the photographic field, and WH=1 is set in step S46; if step S44 is negative, there is no white object (only black or gray objects exist).
It is determined that WH=0 in step S45, and step S
Proceed to step 47. That is, since white always has a higher luminance than the maximum luminance of the chromatic color area, it can be determined whether a white subject exists or not by the above comparison.

In step S47, it is determined whether Wmin<Cmin, and if it is affirmative, it is determined that there is a black object in the scene and BL=1 is set in step S49, and if it is negative, there is a black object in the scene. It is determined that there is no black object (only white or gray objects exist), and BL=0 is set in step S48. After that, the process returns to FIG. That is, since black always has a lower luminance than the minimum luminance of the chromatic color area, it can be determined whether or not a black subject exists by the above comparison.

In step S5 of FIG. 6, exposure calculation processing is performed. The details of this exposure calculation process are shown in the subroutine of FIG. 11, and this is controlled by the exposure calculation section 14. In FIG. 11, in step S51, WH=1 and BL=
1 or not, and if it is affirmative, that is, if both black and white objects are present in the field, in step S52, the exposure value BVa is calculated by BVa=(Wmax+Wmin)/2. Returning to the process in FIG. According to this formula, the exposure value BVa is the average of the maximum brightness value and the minimum brightness value in the achromatic color area, and this is the normal exposure value. Further, if step S51 is denied, step S5
In step S54, it is determined whether WH=1 and BL=0, and if it is affirmative, that is, if there is a white subject and no black subject in the field, then in step S54,
Exposure value B is determined by BVa=(Wmax+2Cmin)/3
After calculating Va, the process returns to the process shown in FIG. According to this formula, the exposure value BVa is a value that is weighted darker than usual, that is, a value on the overexposure side.

Furthermore, if step S53 is negative, it is determined in step S55 whether WH=0 and BL=1, and if affirmative, that is, there is a black object in the field and a white object is present. If the subject does not exist, in step S56, the exposure value B is determined by BVa=(2Cmax+Wmin)/3.
After calculating Va, the process returns to the process shown in FIG. According to this formula, the exposure value BVa is a value that is weighted brighter than usual, that is, a value that is underexposed.

If step S55 is negative, that is, if there is neither a black subject nor a white subject in the photographic scene, then in step S57, the exposure value BVa is calculated from BVa=(Cmax+Cmin)/2. The process returns to the process shown in FIG. This is also a normal exposure value.

When it is determined in step S6 of FIG. 6 that the release button is fully pressed, the process proceeds to step S7.
Exposure control (shooting) based on the exposure value BVa determined in
and terminate the process. If step S6 is negative, the process advances to step S8; if it is determined in step S8 that the release button is pressed halfway, the process returns to step S6; if it is determined that the release button is not pressed halfway, the process ends. let

The above is the control procedure by the control circuit 10. According to this procedure, when a white subject and a black subject coexist in an achromatic area, or when there is neither a white subject nor a black subject, photography is performed at the normal exposure value. . Additionally, if there is a white subject in the achromatic area and there is no black subject, the photograph will be taken with an exposure value that is higher than the normal exposure value, thereby making it possible to photograph a white subject as white. . Furthermore, if there is a black subject in the achromatic area and there is no white subject, the photograph will be taken with an exposure value that is lower than the normal exposure value, thereby making it possible to photograph a black subject as black. .

In the configuration of the above embodiment, the photometric element 6
Furthermore, the photometric circuit 7 constitutes a photometric means, the color discrimination section 12 constitutes a discrimination means, the monochrome discrimination section 13 constitutes a discrimination means 13, and the brightness calculation section 11 and the exposure calculation section 14 constitute an exposure value calculation means.

Note that the formula for determining the exposure value is not limited to the one shown in FIG. Other formulas may be used as long as the exposure value is lower than the normal exposure value when there is a black subject in the achromatic area and there is no white subject.

-Second Embodiment- Next, a second embodiment of the present invention will be described with reference to FIGS. 12 to 14. In the first embodiment described above, Wmax and Cmax and Wmin and Cm are respectively set in the process of FIG.
Black and white discrimination is performed by simply comparing the size of in.
If (x, y) corresponding to Cmax and Cmin, more specifically, (x, y) corresponding to the chromatic regions where the subject brightness is maximum and minimum, is near the boundary of the ellipse in FIG.
The size relationship between Wmax and Wmin becomes delicate. Therefore, in this embodiment, the xy chromaticity diagram is divided into three areas I, II, and III as shown in FIG.
Weighting is applied to Cmax and Cmin during comparison depending on which area (x, y) corresponding to min is included.

FIGS. 13 and 14 show step S44 in FIG.
A flowchart corresponding to steps S49 to S49 is shown. Figure 1
3, if step S41 (FIG. 10) is negative, that is, if the object scene contains both chromatic and achromatic regions, the process advances to step S101. In step S101, in which area of FIG. 12 does (x, y) corresponding to Cmax obtained in the process of FIG. Determine whether the When it is determined that the area is 1, it is determined in step S102 whether Wmax>Cmax×0.8, and if it is affirmative, the WH is determined in step S103.
=1, and if negative, in step S104, WH=0 is set and the process proceeds to step S105. On the other hand, step S101
If it is determined that the area is 2, step S2 in FIG. 14(a)
Proceeding to step S202, it is determined whether Wmax>Cmax×0.9, and if it is affirmative, the WH is determined in step S203.
=1, and if negative, in step S204, WH=0 is set and the process proceeds to step S105. Further, if it is determined in step S101 that the area is 3, step S30 in FIG. 14(b)
1, similarly to the first embodiment, it is determined whether Wmax>Cmax, and if it is affirmative, WH is determined in step S303.
=1, and if negative, in step S304, WH=0 is set and the process proceeds to step S105.

In step S105, it is determined in which area (x, y) corresponding to Cmin is included. If it is determined that area 1 is included, in step S106, Wmin<
It is determined whether Cmin×1.2. If step S106 is affirmed, BL=1 is set in step S107, and if negative, BL=0 is set in step S108. Further, if it is determined in step S105 that the area is area 2, step S206 in FIG. 14(c)
In step S207, it is determined whether Wmin<Cmin×1.1.
= 1, and if negative, WH = 0 in step S208. Furthermore, if it is determined in step S105 that the area is 3, the process proceeds to step S306 in FIG. 14(d), and if Wmin<
It is determined whether Cmin or not, and if it is affirmative, the WH is
= 1, and if negative, WH = 0 in step S308.

By weighting Cmax and Cmin in this way, the effect of improving the accuracy of black and white discrimination can be obtained. Note that the weighting amount is not limited to the example. Further, in the first and second embodiments described above, an example was shown in which photometry is performed for the entire object field, but photometry may be performed for a predetermined area in the object field. An example is shown in FIG.

FIG. 15 shows a photometric element in this example, and this photometric element 60 is composed of three photometric elements 60A, 60B, and 60C corresponding to three focus detection areas in the field. That is, in this example, the focus detection area and the photometry area overlap. Note that the individual divided elements 6A constituting each of the photometric elements 60A to 60C have the same configuration as described above. As a result of performing focus detection in the above three focus detection areas, the camera determines which area of the subject to focus the photographing lens on, and also determines which area of the subject to focus on, and the determined focus detection area (hereinafter referred to as the focus area). Perform photometry. In other words, each of the photometric elements 60A to 60C is operated via the photometric circuit 7 described above, and a brightness value is calculated based on the photometric signal Y obtained by the photometric element in the focusing area, and each focal point is detected in the same manner as described above. Determine whether the object in the area is chromatic or achromatic. Then, the maximum brightness Cmax and minimum brightness Cmin of the chromatic color area are compared with the maximum brightness Wmax and minimum brightness Wmin of the achromatic color area included in the determined focus area, and the achromatic color area within the focus area is determined. Determine whether a white or black object exists in the area. After that, the exposure value is determined by the same procedure as in FIG. According to this, black and white discrimination can be performed for the subject in the in-focus area, that is, the main subject, so
If the main subject is white, it will appear white, and if the main subject is black, it will appear black. Also, instead of the photometric element 60, a photometric element 6
It is also conceivable to use only the vicinity of the region that overlaps with the in-focus region.

In the above, a filter having the sensitivity characteristic shown in FIG. 4 was used, but even if a filter having the sensitivity characteristic shown in FIG. Can be distinguished.

FIG. 16(a) is a diagram showing the sensitivity characteristics of a three primary color filter used, for example, in a color television. In such a filter, a sensitivity distribution as shown in Fig. 16(b) can be obtained by determining Y = 0.30R + 0.59G + 0.11B, and by multiplying this Y by a predetermined proportionality constant, the luminance can be calculated. You can find the value. In this case, since B:G:R=1:1:1 for achromatic colors, B:G:
By determining the amount of deviation of R from 1:1:1, it is possible to determine whether the color is a chromatic color or an achromatic color. For example, if B/G and R/G are both 0.8 or more and 1.2 or less, it may be determined that the color is achromatic.

In addition, for a general film, V'(λ
), it has a sensitivity characteristic with a broader range than the above-mentioned y(λ), that is, the standard luminous efficiency V(λ). Therefore, the photometric signals X, Y, Z or R, G, B in FIG.
If the sensitivity characteristic V'(λ) is determined based on this and the brightness value is calculated based on this, it is possible to obtain an accurate brightness value that matches the sensitivity characteristic of the film.

Furthermore, in the above, black and white discrimination is performed based on the brightness values of the chromatic color area and the brightness value of the achromatic color area.
Since the photometric signal Y is proportional to the brightness value, it is possible to similarly discriminate between black and white based on the photometric signal Y for the chromatic color area and the photometric signal Y for the achromatic color area.

[0039]

According to the present invention, a photometric means is provided which outputs a photometric signal containing information related to the color of a subject located in a plurality of areas in a field, and each area is determined based on the photometric signal. It determines whether the subject in the photo is chromatic or achromatic, and determines a predetermined value based on the photometric signal corresponding to the achromatic color area that is determined to be achromatic and the photometric signal that corresponds to the chromatic color area that is determined to be chromatic. It is determined whether a white or black object exists in the achromatic color area of Black and white subjects can be photographed as white.

[Brief explanation of the drawing]

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

FIG. 2 is a diagram showing the configuration of a photometric element.

FIG. 3 is a diagram showing the configuration of a divided photometric element constituting the photometric element.

FIG. 4 is a diagram showing three sensitivity characteristics of each divided photometric element.

FIG. 5 is an xy chromaticity diagram.

FIG. 6 is a main flowchart.

FIG. 7 is a flowchart showing a subroutine for calculating brightness values.

FIG. 8 is a flowchart showing a subroutine for color determination.

FIG. 9 is a flowchart showing a subroutine for black and white determination.

FIG. 10 is a flowchart following FIG. 9;

FIG. 11 is a flowchart showing a subroutine for calculating exposure values.

FIG. 12 is an xy chromaticity diagram according to a second embodiment of the present invention.

FIG. 13 is a flowchart showing part of black and white determination.

FIG. 14 is a flowchart following FIG. 13;

FIG. 15 is a diagram showing a photometric element according to another example.

FIG. 16 is a diagram showing a modified example of sensitivity characteristics of a filter.

FIG. 17 is a diagram showing the difference between standard luminous efficiency and film sensitivity characteristics.

[Explanation of symbols]

6 Photometric element 6a　Divided photometry element 7 Photometry circuit 8 Exposure control circuit 10 Control circuit 11 Brightness calculation unit 12 Color discrimination section 13 Black and white discrimination section 14 Exposure calculation section

Claims (2)

[Claims] 1. A photometer for measuring light in a plurality of areas in a photographic field and outputting a photometering signal including information related to the color of the subject located in each area; a first discriminating means for discriminating whether the subject in the photograph is chromatic or achromatic; a photometric signal corresponding to the achromatic region determined to be achromatic; and a photometric signal corresponding to the chromatic region determined to be chromatic. a second determining means for determining whether or not a white or black subject exists in a predetermined achromatic region based on the photometric signal; 1. An exposure calculation device for a camera, comprising: exposure value calculation means for calculating an exposure value from a signal. 2. The exposure value calculation means is configured to perform an exposure value calculation means when a white subject and a black subject coexist in the predetermined achromatic color area and when neither a white subject nor a black subject exists. In addition to setting the normal exposure value, if there is a white subject in the predetermined achromatic color area and there is no black subject, the exposure value is set to the side above the normal exposure value, and the predetermined achromatic color 2. The camera exposure calculation device according to claim 1, wherein when a black subject exists in the area and a white subject does not exist, the exposure value is set to be lower than the normal exposure value.