JPH0399585A - Automatic exposure adjustor - Google Patents

Abstract

PURPOSE:To adjust an major object existing areas to have an optimum exposure by placing the highest priority to the major area in the center of a screen when the brightness of an area other than the center area is not normal among plural areas resulting from dividing a picked-up screen into plural areas. CONSTITUTION:A picked-up screen is divided into areas A1-A6, in which the area A1 is located in the center of the screen, the area A2 is located around the area A1 and further the areas A2-A6 are placed around the area A2. The priority is decided based on normalized brightness evaluation values V1-V6 of the areas and the area A1 has normally the highest priority, in which the major object exists with the highest possibility normally. When the brightness of the area other than the area A1 is not normal and other low brightness object exists in the area A1, rear light exists, the maximum value of the evaluation value V is large and the other areas than the area whose brightness is not normal are dark, the simple mean value is small and the priority of the area A1 is placed larger. Thus, the exposure is adjusted so that the effect of the abnormal brightness is reduced and the major object in the area A1 has an optimum exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an automatic exposure adjustment device used in an imaging device such as a video camera.

(B) Conventional Technology In video cameras, control of the brightness level of a captured video signal using aperture, gain, etc., or so-called exposure adjustment, is a very important issue along with focus control.

Conventionally, as this automatic exposure adjustment mechanism, a method of detecting the average brightness level, peak value, etc. of the brightness level of the image capturing screen, and controlling the aperture and the gain for the captured image signal based on these levels has been popular.

In this method, if there is a high-brightness part such as a light source in the screen, or if the background is dark, the main subject may not be properly exposed due to the surroundings.

Therefore, the present applicant previously filed Japanese Patent Application No. 63-4344.
We propose countermeasures for these problems.

This measure involves dividing the imaging screen into multiple areas, making the area in the center of the screen where the main subject is likely to be the main area the main area, and making the other areas non-main areas. In the state, after weighting the brightness level of the main area compared to the brightness level of the non-main area, a representative value of the brightness level of the entire screen is calculated from these brightness levels, and by keeping this constant, the main area is After configuring the system so that the exposure adjustment is carried out with emphasis, check whether the brightness level of each area is extremely high or extremely low, that is, whether an abnormally high brightness area or an abnormally low brightness area falls into any area. By adding a function that constantly monitors whether there is an abnormal brightness area and prevents this area from contributing to the representative value of the brightness level if there is an area where an abnormal brightness area exists, the influence of abnormal brightness areas such as light sources can be reduced. Preventing it from happening all over the place.

(C) Problems to be Solved by the Invention The above-mentioned prior art exhibits excellent effects in backlighting or direction lighting conditions, but problems arise when intentionally photographing an abnormally bright area such as a light source. For example, when photographing a light source, the position of the imaging device is naturally fixed so that the light source is located in the main area at the center of the screen, but in this case, the brightness level of the main area becomes significantly large. The brightness level of the main area cannot be involved in calculating the representative value, and the exposure is adjusted so that the area other than the main area is in the optimal exposure state, and the main area becomes extremely bright, making it difficult to photograph the light source itself. .

(d) Means for Solving the Problems The present invention, when an abnormal brightness part exists in any area of the image capture screen, increases the weighting amount of the main area compared to other areas, and It is characterized by increasing the degree of influence of major areas on calculation.

(E) Function Since the present invention is configured as described above, when an abnormally bright part exists in the main area, the optimum exposure state is maintained for this abnormally bright part, and it becomes possible to photograph the abnormally bright part. Further, when an abnormal brightness portion exists in an area other than the main area, it is possible to reduce the influence of this abnormal brightness portion in exposure adjustment.

(f) Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram of the device of this embodiment.

The incident light passes through a lens (1), the amount of light is adjusted by an aperture mechanism (2), and then photoelectrically converted by an imaging circuit (3) and output as a captured video signal. This captured video signal is amplified by a variable gain amplifier (4) and sent to a video circuit, and is also amplified by a variable gain amplifier (4) and sent to a video circuit.
It is fed to an integrator (80).

L P F (22) extracts the low frequency component of the luminance signal in the captured video signal and outputs it to the subsequent switching circuit (26).

The synchronization separation circuit (23) extracts vertical and horizontal synchronization signals from the captured video signal, and the subsequent switching control circuit (25) extracts the vertical and horizontal synchronization signals from the CO of the imaging circuit (3).
Based on the fixed oscillator output used to drive D, the third
A switching signal is issued for screen division over six areas (AI) to (A6) in the figure.

The switching circuit (26) receives the switching signal and switches each region (
Switches sequentially according to A1) to (A6), L P F
(22) The output is time-divided for each region by this switching circuit (26) and supplied to integration circuits (31) to (36), respectively.

The integrating circuits (31) to (36) each include an A/D converter (27) that A/D converts the output of the switching circuit (26) as shown in FIG. circuit(
28) A digital integrator consisting of an adder 4B (29) that adds the output and a latch circuit (28) that latches the added output, and the low frequency component of the luminance signal within the corresponding area is sampled at a predetermined sampling rate. A/D conversion is performed at regular intervals, and this A/D conversion data is integrated over one field period. Here, the integrating circuit (31) outputs the integrated value for one field of the low frequency component of the luminance signal within the area (A1) to the memory (41), and similarly thereafter
A 2 ) (A 3 ) (A4) (A5) (A6)
The integrated value for one field of the luminance signal within the range is calculated from the memory (42) (43) (44) (45) (46) from the integration circuit (32) (33) (34) (35) (36), respectively. ) will be output. Incidentally, the latch circuit (28) is 1
It is reset for each field, and each memory holds the data of each latch circuit immediately before being reset, and the data is updated for every l field.

By the way, the areas (A1) to (86) are respectively (Sl) to (S6), and the area (A1) is located at the center of the screen as shown in FIG. 3, and the area (A2) is located at the area (S1) to (S6). It is located on the outer periphery of AI). Furthermore, an area (A2) is formed around this area (A2).
3) to (A6) are arranged.

When the integration for one field, which is one screen, is completed, the latest integrated value for one field in each area held in the memory (41) to (46) is the brightness evaluation value of each area. (Y
l) to (Y6) are the subsequent simple average circuits (68),
It is output to each normalization circuit and each weighting circuit.

The normalization circuits (5 steps) to (56) convert the luminance evaluation values (Yl) to (Y6) in each region into respective areas (Sl) to (S6
), and the brightness evaluation value per unit area of each region is normalized brightness evaluation value (vl) to (V6) (however, V1=
Y1/Sl, V 2 =Y 2/S2, . . . ).

The priority determination circuit (57) determines each normalized luminance evaluation value (Vl
) to (v6), the priority (weight) of each area is determined. The priority determination process in this priority determination circuit (57) is executed according to the flowchart shown in FIG.
This priority determination process uses so-called fuzzy inference, which treats information with ambiguous boundaries as ambiguous, and specifically uses the following six rules.

[Rule (1)] rif Vl and V2 are close and V 1 and v3 are not close then area (A 1 ) (A 2 ) priority.'' [Rule (2) rif Vl and V2 are not close and V 1 and V3 are close then area (A1), (A3) priority” [Rule (3)
] rif Vl and V2 are not close, and V 1 and v3 are not close, then area (A1) is given priority.'' [Rule (4)] rif Vl and V2 are close and, V 1 and v3 are close then area (A1), (A2) ), (A3) Priority" [Rule (5)] rif tnax (Vi) (i=1 to 6) is small then all areas have the same priority" [Rule (6)] rif max (V i ) is not small and Prioritize then area (A1) with small simple average value.'' These rules are as shown in Figures 6 to 11.
Conditions such as “close” and “small” are “V2/VIJ
rmax (Vi)'' and is defined by a membership function for each input variable, and has the priority (wik) of each area as a conclusion part. In addition, the inference is the usual min
-max method is used.

Next, each rule will be explained in detail.

[Rule (1)] is defined by membership functions as shown in FIGS. 6(a) and (b). FIG. 6(a) shows the membership function for the input variable (V2/Vl), which indicates the degree to which condition (1) of rule (1) "rVl and V2 are close" is satisfied. That is, in order to determine the degree of closeness indicating how close the normalized brightness evaluation value (Vl) of area (A1) and the normalized brightness evaluation value (v2) of area (A2) are, the input variable is set to V2. /Vl, and the membership value (u,,) is obtained by substituting the input variable (V2/Vl) in the latest field into the chevron-shaped membership function that takes the maximum value when V2/V1=1. Seek. Furthermore, V2/V1
When =1, the membership value (u,,) is maximum.

Figure 6(b) shows the input variable (V3/
is a membership function for Vl). That is, in order to determine the degree to which the normalized brightness evaluation value (Vl) of the area (A1) and the normalized brightness evaluation value (U3) of the area (A3) are not close, the input variable is set to V3. /Vl
Then, the input variable in the latest field (
V3/Vl) by substituting the membership value (
u, , ) can be found. Incidentally, when V3/V1=1, the membership value (u, ,) becomes the minimum. In this way, Figure 6 (
Conditions (1) and (2) of rule (1) are satisfied by a) and (b).
The membership value of (u,,)(u.

, ) will be calculated. Note that this calculation is based on the second
This corresponds to S T E P (100) in the flowchart in the figure.

The membership value (u, ,) (u, ,) is ST
In E P (101), the minimum value of both, that is, the smaller membership value is selected as the degree of fulfillment (Ul) of rule (1). In the example of FIG. 6, since u, , <u, , it is set to U 1 '' u 1+.

The operations of S T E P (100) and (101) described above are also executed for the remaining five rules.

[Rule (2)] is defined by valley-shaped and mountain-shaped membership functions as shown in Fig. 77a and (b), and as in the case of Fig. 6, the rule (2) is that rVl and U2 are not close. )
For condition (1), the membership value (u, ,) is closer than (a), and rVl and U3 are closer.''
2) Membership value (U,) for condition (2)
is found from (b), and in 5TEP (101), the smaller membership value (u, ,) (u, ,) is the rule (
2) is selected as the degree of establishment (U2). In the example of Figure 7, u! Since I>uxt, IJ2=uss is set.

[Rule (3)] is defined by a valley-shaped membership function as shown in Figure 88a) and (b), and as in the case of Figure 6, the condition of rule (3) is that rVl and U2 are not close. The membership value (Ul,) for (1) is (a
), and the rule that rVl and U3 are not close (
Membership value (us,
) is determined from (b), and in S T E P (101), the smaller membership value (u=, )(u-) is selected as the degree of fulfillment (U3) of rule (3). In the example of Fig. 8, u, , < u, , so U 3- u s
Set to 1.

[Rule (4)] is defined by a mountain-shaped membership function as shown in Figures 99a and (b), and the membership value (u , ,) is closer than (a), and rVl and U3 are closer to each other.''For condition (2) of rule (4), the membership value (U , ,) is found from (b), and S T E
Membership value (u+,)(u
, , ) is selected as the degree of fulfillment of rule (4) (U4). In the example of FIG. 9, U41>U41, so U4=u*t is set.

[Rule (5)] As shown in FIG. 10, the maximum value (max (Vi)
) (where i=1 to 6) is the input variable, and this max(
It is defined by a membership function shown by a simple decreasing straight line indicating the degree to which Vi) is small, and once max(Vi) is determined, the membership value (U, , ) is uniquely determined. Note that this membership value (u,,) becomes smaller as max(Vi) becomes larger. S T E P (101
), there is only one membership value for rule (5), so after rule (5) is established (U5) becomes U5
;u, is set.

[Rule (6)], as shown in Figures 11(a) and (b), is a membership function with a simple increasing straight line with max (Vi) as an input variable, as in rule (5), and a total normalized luminance evaluation. It is defined by a membership function of a simple decreasing straight line with values (Vl) to (U6) as input variables. That is, in the membership function of FIG. 11(a), rmax(V
In order to judge the degree to which max(Vi) is not small under condition (1) of rule (6) that ``i) is not small,'' once max(Vi) is determined as an input variable, the membership value (U, , ) is determined. can be determined. Note that this membership value (u,,) becomes smaller as max(Vi) becomes smaller. In addition, in the membership function in Figure 11(b), the rule that "the simple average value is small" (
If the simple average value is determined as an input variable in order to determine the degree to which the simple average value (Z, ) is small in condition (2) of 6), the membership value (u, 2) can be determined.

Note that this membership value (u at) becomes smaller as the simple average value becomes larger. S T E P (1
,01,), the membership value (us+) and (u
, , ) to determine the degree of establishment of rule (6) (
U6) is set as U6=u1.

As described above, it is determined in S T E P (102) that the calculation of the degree of establishment (Ui) (i = 1 to 6) for all rules in S T E P (100) (101) has been completed. Then, in STE P (103), the priority (Wk) (k; 1 to 6) for each area is calculated. This priority (Wk) is calculated by weighted averaging of the conclusions based on the degree of establishment of each rule, as shown in the following equation.

In this formula (A), wik is the priority for each area regarding each rule, and is determined individually for each rule.

For example, regarding rule (1), “area (AI), (
In order to numerically indicate "prioritize A2)," the priorities of areas (A1) to (A6) (w++) to (
w,,) is the Wth = w,, = 3 W+ 2 = W14 = W IH= W I6 =
It is preset to 1. That is, the priority of area (AI) (A2) for rule (1) with respect to other areas is set to three times. Note that this priority setting is based on experiments conducted in advance.

Regarding rule (2), in order to indicate "give priority to areas (A1) and (A3)" as the conclusion part, the priority of each area (W, , ) to (wo) is W亥1:V/23 = 3 w z t = W X 4 = W Mayuts = W
It is set in advance as s s = 1.

Regarding rule (3), "give priority to area (A1)"
In order to show the conclusion part, the priority of each area (Ws+)
〜(W,) is w,,=3 W s * = W s s = W s 4 = W
It is set in advance that s s = W s a = 1.

Regarding rule (4), “area (Al), (A2),
In order to show "Prioritize (A3)" as the conclusion part, the priority of each area (W,,) to (W,,) is W (l = W
4! = W 4 B = 3W44 = V/4
It is set in advance that g = W 4 @ = 1.

Regarding rule (5), [all areas have the same priority]
In order to show as a conclusion, the priority of each area (w, ,
, ) to (Wss) are W @ 1 = W ■ = W
13 = W @ 4 = Wg 3 = Wg g
= 1 in advance.

Regarding rule (6), "give priority to area (A1)"
In order to show as a conclusion, the priority of each area (W,,)
〜(W,) is w,,=3 W @*= W *s= W a4= W *s= W
14=1 is set in advance. In addition, the simple average value (
Z, ) is calculated by a simple average circuit (68) as described later.

Considering the priority (Wk) considering all rules using the priority of each area in each rule set in this way using the examples of FIGS. 6 to 11, for area (A1),
The formula (A,) becomes. In this formula (B), =u11.3+tzz.3+u, +.3+u4.・3+
U1.・1+u,,・3=u ++"u 鞞+u s+"u 4-小u jl"u @1, so the priority (Wl) of the area (A1) is L = (3u+ 1 + 3ut *" 3us + +3
us g”um +”3ua s)/(u+t”ut
t+um++uat+Ijmt"11m) Similarly, the priorities (W,) to (W,) are calculated as 8.The priority (Wk) of each area determined by fuzzy inference for all rules is calculated by the weighting circuit ( 61) to (66).The weighting circuits (61) to (66) perform so-called priority processing by weighting each region with priorities (W,) to (W,).In other words, each luminance evaluation Yi-Wi (i=1
~6) is calculated. All of the luminance evaluation values weighted in this way are supplied to a weighted average circuit (67). The weighted average circuit (67) includes weighting circuits (61) to (6).
6) Divide the added value of the output by the sum of the products of each priority and area to output a weighted average value (2,). That is, calculate. Note that Si (i=1 to 6) indicates the area of each region.

The simple averaging circuit (68) adds up all of the respective brightness evaluation values (Yi) and calculates the added value as the area (S) of the entire screen.

+S, +...S,) to obtain the simple average of the entire screen. Note that this simple average value (Zl) is calculated based on each brightness evaluation value (
Yi) is weighted by weighting circuits (61) to (66) with priorities (W, ) to (W,) all set to "1", and a weighted average circuit (67) calculates equation (C). It is the same value as the one we did.

The simple average value (2,) calculated as described above and the weighted average value (Z) are input to the divider (69), m = Z
, /Z, and this division value (m) is input to the gain control circuit (70) and the target level control circuit (71).

The gain control circuit (70) supplies a target level (P) to a comparator (5) that controls the gain of the variable gain amplifier (4). This target level (P) is the optimum level that can obtain the optimal exposure for the image capture screen when m=1, that is, when the simple average value (Z8) and the weighted average value Z,) are equal and the brightness distribution of the image capture screen is not considered. It is set at the target level (P, ) and follows the division value (m), which is a correction value, so as to always satisfy P -m P .

Therefore, as a result, the weighted average value (Z,
) becomes the optimal target level (Po).
) will change.

The comparator (5) integrates the captured video signal over a sufficiently long time constant (for example, one field period) and outputs the output of the integrator (90) indicating the brightness level of the corresponding field and the target level (P). This comparison output is supplied to the variable gain amplifier (4) so that the integrated output reaches the target level (P).
By controlling the gain so as to match , AGC is applied to the video signal in consideration of weighting processing.

The target level control circuit (71) supplies a target level (Q) to a comparator (72) that controls the aperture amount of the aperture mechanism (2), and this target level (Q) is equal to the target level (
Similarly to P), when the division value (m) satisfies the condition m==1, it is set to the optimal target level of Q = q o, and between the division value (m) and the condition Q = mq, The weighted average value (2,
The target level (Q) changes so that ) always matches the optimal target level (qo).

A comparator (72) is connected to the target level (Q) and an integrator (80).
) output, and this comparison output is compared with the aperture mechanism (
2), and based on this comparison output, the wringer i11!
(2) is driven, and the aperture amount of the aperture mechanism (2) is controlled so that the integrated output indicating the brightness level of the relevant field matches the target level (Q). Incidentally, the time constant of the integrator (80) is equal to that of the integrator (90), and the time constant of the integrator (80) is equal to that of the integrator (90).
(2> is set so as not to follow instantaneous changes in the captured video signal.

As mentioned above, the variable gain amplifier (4) and the aperture mechanism (2)
The target level (
P )(Q ) changes according to the weighted average value (2,) that has been subjected to weighting processing, so the variable gain amplifier (
4) and optical exposure adjustment using the diaphragm mechanism (2), weighting processing is fully taken into account. For example, if the simple average value (Z, ) of the entire screen is 120", , ) is 100", sufficient brightness is obtained over the entire screen, but sufficient brightness cannot be obtained if only the areas that must be prioritized according to rules (1) to (6) are focused. Therefore, the central area is dark, etc., and the division value (m) becomes m = 1 and 2, and the target levels (P) and (Q) are respectively P = mP, ,Q
:= m q , and as a result, the gain of the variable gain amplifier (4) also increases, the aperture amount of the aperture mechanism (2) also decreases, and optimal exposure adjustment is performed for the priority area.

Next, how the rules (1) to (6) affect exposure adjustment will be explained for each rule. Rules (1) to (4) are the basics of priority processing, and when the brightness evaluation values of areas (AI), (A2, and A3) are close to each other, they work to increase the priority of that area. do.

For example, as in the prior art, the area (A I ) (A 2 ) (A
Regarding 3), if you simply give the same priority to areas (A4, A5, and A6) and photograph the subject (S) in a backlit situation as shown in Figure 5, only area (A2) will have the same priority. Since a bright background such as the sun comes in, it is not possible to correct the subject (S) appropriately. Therefore, rules (1) to (4)
), both areas (AI) (A3) are dark and only area (A2) is bright, so the normalized brightness evaluation value (Vl)
For (V2) (V3), V1#V3≠V2 holds,
Since conditions (1) and (2) of rule (1), condition (2) of rule (3), and condition (1) of rule (4) are difficult to hold, only the probability of rule (2) being satisfied is extremely high, and the area ( AI
) (A3) has a higher priority, and these areas (A1)
Emphasis is placed on the subject (S) within (A, 3), and the optimum exposure state is established for this subject (S). These series of rules are particularly effective when backlit.

Rule (5) corresponds to the case where the entire screen is dark, and when the maximum value of the normalized brightness evaluation value is not large, priority processing is not performed and the average value of the screen is used as the representative value. In addition, as a rule when the entire screen is dark, the following rule (5)'
It is also possible to substitute rule (5).

[Rule (5)’] “The IF aperture is wide open.

Then all areas have the same priority.'' This rule (5) is based on the aperture mechanism (2) that reduces the darkness of the image capture screen.
If the aperture is quite open, that is, the aperture is quite large, the imaging screen is assumed to be dark, and the priority is set the same for all areas, making unnecessary corrections possible. It works to suppress The membership function of rule (5)' with this degree of openness as an input variable is illustrated in Figure 12, and the priority of each area is w,
, = w 1! =W s s =W s 4
= W * s = W s a = 1. At this time, to detect the degree of opening of the aperture, the drive voltage value for operating the aperture mechanism (2) is set to the A/D converter (200) as shown in FIG.
) and feeding it back to the priority determining circuit (57), or the aperture mechanism (2) is driven by a stepping motor whose rotor position can be counted, and the opening direction of this motor is Various methods are conceivable, such as making the degree of opening correspond to the number of steps, and further providing a separate sensor to detect the degree of opening. Note that the amount of aperture of the aperture mechanism (2) changes in inverse proportion to the voltage value of the comparator (72). That is, the degree of opening changes in proportion to the voltage value. In addition, as a rule for when the entire screen is dark, rule (5)
It is also possible to use both ) and (5)°.

Rule (6) corresponds to the case where an extremely bright object such as a light source, a so-called abnormal brightness area, appears in the screen, and since the abnormal brightness area is in one of the areas, the normalized brightness evaluation is The maximum value (Vi) is not small, but the simple average value (2,
) is small and the entire area other than the area where the abnormal brightness portion is present is dark, the area (AI) is given priority unconditionally.

Therefore, if the photographer positions the abnormal brightness area within the area (A1) at the center of the screen in order to photograph the abnormal brightness area under a dark background, the normalized brightness evaluation value (V
The maximum value of ′i) is (V, ), which is a large value, but
The simple average value (21) is small and the area (A I ) is prioritized. Therefore, the exposure is adjusted so that the brightness level of the area (AI) is at the optimal level, that is, the abnormal brightness part in the area (AI) is in the optimal exposure state, and as a result, it is possible to photograph the abnormal brightness part. becomes. At this time, areas (A2) to (A
In 6), the exposure adjustment described above results in a dark state with extremely low brightness, but this is unavoidable since the highest priority is given to photographing the abnormally bright part.

In addition, when the abnormal brightness area exists in any area other than area (A1) and there is another subject in area (A1) with lower brightness than the abnormal brightness area, a backlight condition will occur, and the normalized brightness evaluation value ( The maximum value of Vi ) becomes smaller, and in this case also, the priority of area (A1) becomes higher. Therefore, the exposure adjustment is performed so that the influence of the abnormal brightness portion is reduced and the main subject in the area (AI) is brought to the optimum exposure state.

Note that the division of regions and the setting of each rule are not limited to this embodiment, and various forms can be considered. In addition, the switching circuit in Figure 1 (
It goes without saying that operations 26) to division@(69) can be processed by software using a microcomputer.

Further, in the above embodiment, the optimum target level (P, ) of the imaging screen without considering the luminance distribution is set in advance, and the division value (m ) as a correction value by the optimal target level (P, ) to indicate the brightness level of the captured video signal (90)
Optimum exposure control is achieved by comparing with the output, but as shown in Figure 13, the optimal target level (P,)
Weighted average value (Z□) and target level memory (91)
target level (PO) stored in (where P and ° are values obtained by digitizing the target level (Po))
are directly compared with the comparator (92), and based on the comparison result, the gain of the variable gain amplifier (4) is controlled, and the aperture amount of the aperture mechanism (2) is controlled to adjust electrical and optical exposure. It is also possible to do so. For example, the weighted average value (2
,) is smaller than the target level (P6'), it is assumed that the image capture screen is underexposed compared to the optimal exposure state considering the luminance distribution, and the variable gain amplifier (4 ) and increases the gain of the aperture mechanism (2).
When the weighted average value (Z,) is larger than the target level (P, °), it is assumed that the exposure is overexposed compared to the optimal exposure state, and z,=
The brightness can be reduced by lowering the gain of the variable gain amplifier (4) and increasing the aperture amount of the aperture mechanism (2) so that P0.

(G) Effects of the Invention According to the present invention as described above, when an abnormal brightness area such as a light source is selected as the main subject and the abnormal brightness area is present in the main area, the optimum exposure is set for this abnormal brightness area. is maintained, and when an abnormal brightness area is present in a non-main area when an abnormal brightness area is not selected as the main subject, exposure adjustment is performed to suppress the influence of this abnormal brightness area.

[Brief explanation of drawings]

1 to 12 relate to an embodiment of the present invention, in which FIG. 1 is an overall circuit block diagram, FIG. 2 is a flowchart, FIG. 3 is an explanatory diagram of screen division, and FIG. 4 is a main circuit. The block diagram, Figure 5 is a diagram showing an example of the imaging screen, and Figure 6 is the rule (
Figure 7 is an explanatory diagram of rule (2), Figure 8 is an explanatory diagram of rule (3), Figure 9 is an explanatory diagram of rule (4), and Figure 10 is an explanatory diagram of rule (5). FIG. 11 is an explanatory diagram of rule (6), FIG. 12 is an explanatory diagram of rule (5), and FIGS. 13 and 14 are circuit block diagrams of other embodiments of the present invention. It is. (31) (32) (33) (34) (35) (36)・
... Integration circuit, (61) (62) (63) (64) (6
5) (66)... Weighting circuit, (70)... Gain control circuit, (71)... Target level control circuit, (57
)...priority determination circuit

Claims (3)

[Claims] (1) A brightness evaluation value detection means that divides an imaging screen into at least one main area and a plurality of non-main areas and detects the brightness level of each area as a brightness evaluation value, and determines the priority of each of the areas. a priority determining means; a calculation means for weighting the brightness evaluation values of each area according to the priority to obtain a representative value of the brightness level of the entire screen; and an exposure controller for adjusting exposure according to the representative value. An automatic exposure adjustment device, comprising: an adjustment means, wherein when an abnormal brightness portion exists in any region of the imaging screen, the priority of the main region is made higher than that of the non-main region. (2) The automatic exposure adjustment device according to claim 1, wherein the main area is set at the center of the imaging screen. (3) The automatic exposure adjustment device according to claim 1, wherein fuzzy inference is used to determine whether or not an abnormal brightness portion exists in any region of the image capturing screen.