JP2000050153A - Exposure control method, medium storing exposure control program and exposure controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure controller which obtains an appropriate correction value at the time of back light and over-direct light and appropriately controls exposure by means of controlling the exposure in accordance with the correction value. SOLUTION: An exposure control circuit as this device is provided with a block generation circuit 18 dividing a part of or the whole of a screen into plural blocks, a state detection circuit 19 making a luminance level obtained from the prescribed block to a prescribed reference level and judging whether the average luminance values of the whole blocks are within the range of the prescribed reference level or not, a representative luminance calculation circuit 20 calculating the luminance in an arbitrary area consisting of the prescribed block as representative luminance in accordance with the distances to objects and relation between the objects, a rate detection circuit 21 obtaining the rate of the blocks satisfying a threshold condition in the arbitrary area, a correction quantity generation circuit 22 generating correction quantity from the rate and an exposure control circuit 23 deciding an exposure controlled quantity based on the correction quantity and controlling exposure based on the exposure controlled quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure control method, a medium storing an exposure control program, and an exposure control device, and more particularly to a method of controlling a luminance ratio occupying a screen in an exposure control of a digital still video camera using a CCD image pickup device. The present invention relates to exposure control that determines a correction amount in backlight or over-direct light based on a ratio and a change thereof.

[0002]

2. Description of the Related Art Conventionally, in a video camera or a silver halide camera, as a method of judging the state of backlight or over-sequential light and controlling exposure, the luminance of the central area and the central area are focused on the center of the screen. In some cases, the state of backlight or over-directed light is determined by comparing the luminance of the peripheral area excluding the area, and exposure control is performed by performing correction for each of backlight or forward light in accordance with the determination result. For example, there is one disclosed in JP-A-6-225205. In this conventional example, a two-dimensional image is divided into blocks, luminance data is accumulated for each block to obtain accumulated data, and it is determined from the accumulated data of the blocks whether the central portion of the screen is in a backlight state or an over-direct light state. The iris is controlled to an appropriate state by changing the photometric reference value. A typical backlight state as shown in FIG. 8 is 4 × as shown in FIG.
When divided into four blocks, blocks f, g, j, k,
Judgment is made by comparing n, o with the accumulated data of each of the other blocks, and is corrected to the reference at the time of backlight.

[0003]

However, in this conventional method, the backlight is corrected by changing the correction reference value at the time of backlight or over-direct light. However, depending on the position or size of the subject, as shown in FIG. There is a problem that the difference in accuracy between the subject in the backlight state and the other parts is not accurately reflected, and an accurate correction value cannot be obtained, so that accurate exposure control cannot be performed.

The present invention has been made to solve these problems, and it is possible to perform appropriate exposure control by obtaining an appropriate correction value even in the case of backlight or over-directed light and performing exposure control in accordance with the correction value. It is an object of the present invention to provide an exposure control method that can be performed.

[0005]

In order to solve the above-mentioned problems, the present invention converts the luminance of a subject into an electric signal using a solid-state imaging device, and records and / or reproduces the image information based on the electric signal. A digital still video camera for performing an exposure control device for automatically adjusting an exposure state of a screen including a subject, a background, and the like, wherein a block generation unit that divides a part or the whole of the screen into a plurality of blocks; A brightness level obtained from a block is set as a predetermined reference level, and means for determining whether or not the average brightness value of each block is within a range of the predetermined reference level, and according to a distance between the objects and a relationship between the objects. A representative luminance calculating means for calculating luminance in an arbitrary area composed of a predetermined block as a representative luminance; The ratio detecting means for determining the rate of click,
It is characterized in that it includes a correction amount generating means for generating a correction amount from the ratio, and an exposure control means for determining an exposure control amount based on the correction amount and performing exposure control based on the exposure control amount. Therefore, it is possible to perform more appropriate exposure control for the backlight and the over-directed light and for the degree thereof.

Further, the representative luminance calculating means excludes each block having high luminance equal to or higher than a predetermined upper threshold and low luminance equal to or lower than a predetermined lower threshold in an arbitrary area, and averages the remaining blocks to obtain the representative luminance. By calculating, the luminance information excluding the peculiar information can be obtained, and an appropriate luminance ratio can be obtained.

Further, the ratio detecting means calculates the difference between the representative luminance and the luminance of a block in an arbitrary area composed of blocks other than an arbitrary area composed of predetermined blocks determined according to the distance between the objects and the relationship between the objects. By comparing the ratios and calculating the ratio of blocks satisfying the threshold condition in an arbitrary area composed of predetermined blocks, the accuracy of backlight or over-direct light can be accurately determined.

Further, the correction amount generating means generates a correction amount according to each ratio in an arbitrary area composed of predetermined blocks from a ratio of blocks satisfying the threshold condition in an arbitrary area composed of predetermined blocks. Various back light and over-order light can be handled.

Further, the correction amount generating means changes the correction amount according to the comparison result by comparing the ratio of blocks satisfying the threshold condition in an arbitrary area composed of the predetermined block with a predetermined reference value, thereby providing backlight. And the degree of over-direct light.

The correction amount generating means generates a correction amount based on a change in a ratio in an arbitrary area composed of blocks satisfying each of the threshold conditions using a plurality of predetermined threshold conditions. It can correspond to the degree of direct light,
Appropriate exposure control can be performed.

An arbitrary area consisting of a predetermined block is:
When the brightness is equal to or greater than a predetermined threshold, it is considered that there is no difference between the distances of the subjects and that the distance is single, and when the distance of the subjects is far, the area is set smaller than a predetermined value, and the When the subject is regarded as a single object without being located on the near side, and when the subject is mixed on the far side and the near side, the area is set to a predetermined size larger than a predetermined value. This can be reflected by the size of the subject, and the accuracy of backlight or over-direct light can be accurately determined.

According to another aspect of the present invention, an exposure control method divides a part or the whole of a screen into a plurality of blocks, sets a luminance level obtained from a predetermined block as a predetermined reference level, and sets an average luminance value of each block as a whole. Is determined to be within a range of a predetermined reference level, and in accordance with the distance between the objects and the relationship between the objects, the luminance in an arbitrary area composed of the predetermined blocks is calculated as the representative luminance. A ratio of blocks satisfying the threshold condition is obtained, a correction amount is generated from the ratio, an exposure control amount is determined based on the correction amount, and exposure control is performed based on the exposure control amount. Therefore, according to the present invention, it is possible to perform more appropriate exposure control for backlight or over-directed light.

Further, a medium according to another invention has a function of dividing a part or the whole of a screen into a plurality of blocks, a brightness level obtained from a predetermined block as a predetermined reference level, and A function of determining whether or not the average luminance value is within a predetermined reference level range, and calculating the luminance in an arbitrary area including a predetermined block as a representative luminance according to the distance between the objects and the relationship between the objects. A function, a function of calculating a ratio of blocks satisfying a threshold condition in an arbitrary area, a function of generating a correction amount from the ratio, and an exposure control amount determined based on the correction amount and based on the exposure control amount. An exposure control program including a function of performing exposure control is recorded. Therefore, by executing the exposure control program recorded on the medium of the present invention by a computer, it becomes possible to perform more appropriate exposure control for backlight or over-direct light.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A digital still video camera which converts the brightness of a subject into an electric signal using a CCD and records and / or reproduces the image information based on the electric signal, comprising a screen including a subject and a background. An exposure control device that automatically adjusts the exposure state of a block, a block generation circuit that divides a part or the whole of the screen into a plurality of blocks, and a brightness level obtained from a predetermined block as a predetermined reference level, A state detection circuit that determines whether or not the entire average luminance value is within a predetermined reference level range; and a luminance detection circuit that represents the luminance in an arbitrary area composed of predetermined blocks according to the distance between the objects and the relationship between the objects. A representative luminance calculating circuit for calculating as luminance, a ratio detecting circuit for calculating a ratio of blocks satisfying a threshold condition in an arbitrary area, and a correction amount based on the ratio Including a product to the correction amount generating circuit, the exposure control circuit the correction amount determines the amount of exposure control on the basis of the exposure control is performed based on the amount of exposure control.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the exposure control device according to the first embodiment of the present invention. In the figure, the exposure control device of the first embodiment includes a lens 11, an aperture 12,
CCD 13, CDS 14, AGC 15, A / D conversion circuit 16, image signal processing circuit 17, block generation circuit 18, state detection circuit 19, representative luminance calculation circuit 2
0, a ratio detection circuit 21, a correction amount generation circuit 22, an exposure control circuit 23, a focus control circuit 24, and a focus drive circuit 25. Aperture 12
Adjusts the amount of light incident from the lens 11. CCD13
Converts incident light into electrical signals. CDS14 is CC
This is a double correlation sampling circuit that removes noise components included in D13 and amplifies signal components. AGC1
Reference numeral 5 denotes an automatic gain control circuit for automatically adjusting the gain of the CCD 13. The A / D conversion circuit 16 converts an analog signal into a digital signal. The image signal processing circuit 17 mixes the A / D converted image pickup signal into a luminance signal and a color difference signal based on the NTSC system, and changes the image signal into a divided video signal. The block generation circuit 18 accumulates the luminance signal output from the image signal processing circuit 17 in each block to generate a block.
The state detection circuit 19 determines from the block generation circuit 18 whether or not the luminance level is within a certain reference luminance level range. The representative luminance calculation circuit 20 obtains a luminance signal representing a representative area in an arbitrary area. The ratio detecting circuit 21 obtains the ratio of those satisfying the condition of the threshold in an arbitrary area and the change thereof. Correction amount generation circuit 2
2 generates a correction amount based on the ratio obtained by the ratio detection circuit 21. The exposure control circuit 23 determines a control amount based on the correction amount in the correction amount generation circuit 22, and controls each of the aperture, the shutter speed, and the AGC. The focus control circuit 24 generates focus information and obtains a subject distance and a relationship therebetween. The focus drive circuit 25 drives the lens based on the subject distance and its relationship.

Next, when the block generating circuit 18 generates the accumulated luminance of 8 × 6 blocks, that is, the accumulated luminance of the 8 × 6 blocks as shown in FIG. 2 is calculated as Y (i, j) (i =
1 to 8, j = 1 to 6) as an example, and FIG.
The processing flow of the state detection circuit 19 will be described with reference to FIG. The area 5 in FIG. 2 does not include the area 6. In the initial state, it is assumed that the luminance level is not within the range of the reference luminance level.

First, the state detection circuit 19 shown in FIG.
The exposed block generation circuit 18 supplies the cumulative luminance of 8 × 6 blocks (step 31). It is determined whether or not the average luminance value obtained from the accumulated luminance is within the range of the reference luminance level (step 32). This judgment is Y
It corresponds to 1t <Yc <Yut. Yc uses, for example, the average value of all blocks in areas 5 and 6 in FIG. That is, Yc = ΣY (i, j) / 16 (i = 3 to 6, j = 2
To 5). Y1t and Yut are lower and upper thresholds for determining the range of the reference luminance level. If the average luminance value obtained from the accumulated luminance is not within the range of the reference luminance level, qEV exposure is performed (step 34). next,
A correction amount CV is obtained (step 33). This correction amount CV
Is a correction amount up to a reference value T, which is a reference luminance level, and is expressed as, for example, CV = −log ₂ (T / Yc). When implementing, the correction amount CV may be obtained by performing linear interpolation or the like. Then, EV by p + CV (q + CV)
Exposure is performed (step 35). pEV and qEV are arbitrary E such that the entire photometry range can be covered during photometry.
V may be specified.

In a general scene, the subject of each luminance included in the screen has a range of about 5 EV. Therefore, for example, when the photometric range is 9 to 17 EV, if p = 13 and q = 16, the entire area can be covered. If it is determined that the brightness is within the range of the reference luminance level,
The distance between the subjects and the relationship between the subjects are obtained by the focus control circuit 24 and the focus drive circuit 25 in FIG.
The focus control circuit 24 extracts and obtains a high-frequency component of the luminance signal using a bandpass filter or the like while driving the focus information from the distance measurement sensor or the focus drive circuit 25 as a lens.

When the focus information is a high-frequency component of the luminance signal, the maximum value of the distance to the subject is set as the in-focus position. Determined based on the effect of the so-called hill climbing method. For example, bandpass filters A with different cutoff frequencies,
When the focus information is obtained while driving the lens and climbing the hill using B, when the brightness is equal to or more than a predetermined threshold (EV), generally, when there is no predetermined difference in the distance between the subjects, FIG. As shown in FIG. 4A, the position where the maximum value occurs is substantially the same, and when there is a predetermined difference in the distance between the subjects, the position where the maximum value occurs differs greatly as shown in FIG. In some cases, a plurality of maximum values may occur as shown in FIG. In addition, (a) of FIG.
In (b) and (c), the vertical axis represents the focus information, the horizontal axis represents the focus lens position, and the left side is the infinity direction and the right side is the near point direction. The characteristic A means the band pass filter A, and the characteristic B means the band pass filter B. In FIG. 4C,
No particular filter is specified, and any single bandpass filter is used. In FIG. 4B, the position where the maximum value occurs in the bandpass filter A indicates the position of the subject on the short distance side, and the position where the maximum value occurs in the bandpass filter B indicates the position of the subject on the long distance side. In FIG. 4C, the position where the local maximum value 1 occurs represents the position of the subject on the long distance side, and the position where the local maximum value 2 occurs represents the position of the subject on the short distance side. The relationship between the objects is obtained based on the distribution as shown in FIGS. 4 (a), 4 (b) and 4 (c).

Next, the calculation of the representative luminance in an arbitrary area will be described. When the brightness of an arbitrary area is equal to or more than a predetermined threshold (EV), the size of the area is changed according to the distance between the objects and the relationship between the objects. For example, when there is no difference between subjects, it is regarded as a single subject, and when the subject is on the short distance side, and when the subjects are mixed at a long distance and a short distance, the subject on the short distance side is prioritized. , The size of the area is made larger, for example, all blocks in areas 5 and 6 in FIG. When there is no difference in the distance between the subjects and it is regarded as a single object, and when the distance between the subjects is far, the size of the area is made smaller, for example, all blocks in the area 6 in FIG. In all these blocks, Lt <Y (i, j)
<Ht that satisfies Ht, YM (i, j)
And Here, Lt and Ht are predetermined thresholds for excluding low-luminance blocks and high-luminance blocks. When Ym is equal to or less than a predetermined threshold value, the representative luminance RY is RY = ΣY (i, j) / 16 when the subject distance is closer.
(I = 3-6, j = 2-5), and in the case of the far side,
RY = ΣY (i, j) / 4 (i = 4 to 5, j = 3 to
4). Otherwise, RY = ΣYM (i,
j) / Ym.

Next, the ratio detection processing will be described.
RY is compared with the block Y (i, j) in area 1.
That is, the ratio of the blocks satisfying the following conditions to all the blocks in the area 1 is obtained. RY × BLt1 <Y
BLr1 is the ratio of those satisfying (i, j) (the backlight ratio).
(%), RY> Y (i, j) × OLt1 The ratio (over-direct light ratio) is OLr1 (%), the other ratio (forward light ratio) is NLr1 (%), and BLt1 is a predetermined value against backlight. The threshold OLt1 is a predetermined threshold for over-ordered light, and BLt1 ≧ 1 and OLt1 ≧ 1. BLr1, O
Lr1 and NLr1 are compared, and the one with the highest ratio is the ratio (representative ratio) of area 1 as Rr1. Also, backlight,
Similarly, with respect to the predetermined threshold values BLt2 and OLt2 for over-ordered light, the ratio of the one satisfying RY × BLt2 <Y (i, j) (the backlight ratio) is BL2r1 (%), and RY> Y.
The ratio of (i, j) × OLt2 is satisfied (over-forward light ratio) is OL2r1 (%), and the other ratio (forward light ratio) is NL2r1 (%), BL2t1, OL2r1, and NL2r.
1 and the one with the highest ratio is defined as the ratio (representative ratio) R2r1 of the area 1. Note that BLt1 <BLt2,
OLt1 <OLt2, and BLt2 ≧ 1 and OLt2 ≧ 1.

Next, a coefficient for a change in the ratio due to a difference in a predetermined threshold value is obtained. BLr1, OLr1, NLr1, BL2r1, which occupy CT1 with Rr1 and R2r1 when a predetermined threshold value for back light and over-order light is changed
The coefficient is determined by a change in OL2r1 and NL2r1.

The threshold is changed from BLt1 → BLt2, OLt1 → O
When Lt2 is changed, the change from Rr1 to R2r1 is represented by cb11, Bb, the coefficient when BLr1 → BL2r1.
The coefficient at the time of Lr1 → NL2r1 is cb12, NLr1
→ The coefficient at the time of NL2r1 is cn1, OLr1 → NL2
The coefficient at the time of r1 is co12, and the coefficient at the time of OLr1 → OL2r1 is co11 (cb11>cb12> cnl, co11>co12>
cnl), and a coefficient corresponding to each change is selected and set as a coefficient CT1.

That is, the change from Rr1 to R2r1 is
When BLr1 → BL2r1, the coefficient CT1 = cb11,
When BLr1 → NL2r1, the coefficient CT1 = cb12,
When NLr1 → NL2r1, the coefficient CT1 = cn1, O
When Lr1 → NL2r1, the coefficient CT1 = co12, O
When Lr1 → OL2r1, the coefficient CT1 = co11. As described above, the area 1 in FIG. 2 has been described, but the same processing is performed for the areas 2 to 4.

In the correction amount generation circuit 22 shown in FIG. 1, the correction amount mEV is calculated based on the result of the ratio detection circuit 21 as follows.
Decide.

MEV = W (Rr1) × CT1 × NL1 +
W (Rr2) × CT2 × NL2 + W (Rr3) × CT3
× NL3 + W (Rr4) × CT4 × NL4

NL1 to NL4 are existing correction amounts of the areas 1 to 4. W (Rr1) to W (Rr4) are area 1
A weight of ~ 4 means that the weight is arbitrarily changed according to the ratio in each area. Rr1 to Rr4 are areas 1 to
4 is the representative ratio.

Here, taking area 1 as an example, when Rr1 is BLr1, W (Rr1) is a weight for correcting the reference value T in the over direction. Also, if Rr1 is O
In the case of Lr1, W (Rr1) is a weight for correcting the reference value T in the under direction. Further, if Rr1 is NL
In the case of r1, W (Rr1) is a weight independent of the ratio for performing correction in the over or under direction with respect to the reference value T. The same applies to the areas 2 to 4.

FIG. 5 shows an example of the weight W (Rr1). In the figure, the vertical axis is W (Rr1), the horizontal axis is Rr1 (%),
BL, OL, and NL are a backlight ratio, an over-forward light ratio, and a forward light ratio, respectively, and represent the case where Rr1 is BLr1, OLr1, and NLr1. CT1 to CT4 are coefficients based on the change in the backlight ratio, the excessive light ratio, and the normal light ratio occupied by the representative ratio when the predetermined threshold value for the backlight 1 and the area 4 is changed.

FIG. 6 shows a specific image. (A) and (b) in the same figure are for BLt1 and OLt1, and (c) and (d) in the same figure are for BLt2 and OLt2. (A) and (c) in the same figure are for the same scene, but with different thresholds. The same applies to (b) and (d) of FIG. Numerals in the figure, 100, 85, 80 and 50, represent the representative ratios (%) of Rr1 to Rr4 and R2r1 to R2r4.
It is. When the threshold value is changed from (a) to (c) in FIG. 6, the representative ratio of the areas 1 to 4 hardly changes, and the backlight ratio, the over-forward light ratio, and the forward light ratio selected by the representative ratio are changed. Since the type does not change, the weight of the representative ratio and the coefficient C
T1 to CT4 are increased. That is, since the degree of backlight is high, the direction of correction is increased. When the threshold is changed from (b) to (d) in FIG. 6, the representative ratio of the areas 1 to 4 and the backlight ratio, the over-direct light ratio, and
Since the type of forward light ratio changes, compared to the above case,
The weight of the representative ratio and the coefficients CT3 and CT4 are reduced.
That is, since the degree of backlight is smaller than that in the above case, the direction is not so much corrected.

The exposure control circuit 23 of FIG. 1 performs exposure control by arbitrarily determining the aperture, shutter speed, and AGC exposure control amount based on the mEV output from the correction amount generation circuit 22 with respect to the reference value T.

FIG. 7 is a block diagram showing a configuration of an exposure control circuit according to a second embodiment of the present invention. In the figure,
The CDD camera unit 71 includes the lens 11, the aperture 12,
This corresponds to a device including the CCD 13, CDS 14, and AGC 15. Further, the A / D conversion section 72 corresponds to the A / D converter shown in FIG.
The image signal processing unit 73 corresponds to the image signal processing circuit 17 in FIG. Further, the block generation unit 75 corresponds to the block generation circuit 18, and the exposure correction unit 76 corresponds to a unit including the state detection circuit 19, the representative luminance calculation circuit 20, the ratio detection circuit 21, and the correction amount generation circuit 22. Further, the CCD camera control unit 80 includes an exposure control circuit 2
3 and the focus drive circuit 25, and the focus control unit 78 corresponds to the focus control circuit 24. The frame memory 74 and the memory card 77 store the calculated brightness, the correction amount, and the like, and a control program. A second embodiment having such a configuration is shown in FIG.
1 can be performed by digital processing such as a microprocessor, and the same processing as in FIG. 1 can be performed.

It is needless to say that the present invention is not limited to the embodiments described above, and that various modifications and replacements can be made within the scope of the claims.

[0034]

As described above, according to the present invention,
Block generation means for dividing a part or the whole of the screen into a plurality of blocks, and a luminance level obtained from the predetermined block as a predetermined reference level, and an average luminance value of each block is within a range of the predetermined reference level. Means for determining whether or not there is, a representative brightness calculating means for calculating the brightness in an arbitrary area formed of predetermined blocks as representative brightness according to the relationship between the distance of the subject and the subject, and a threshold condition in the optional area Ratio detecting means for calculating a ratio of blocks satisfying the condition, a correction amount generating means for generating a correction amount based on the ratio, an exposure control amount being determined based on the correction amount, and performing exposure control based on the exposure control amount. It is characterized by including exposure control means. Therefore, it is possible to perform more appropriate exposure control for the backlight and the over-directed light and for the degree thereof.

The representative luminance calculating means excludes each block having high luminance equal to or higher than a predetermined upper threshold and low luminance equal to or lower than a predetermined lower threshold in an arbitrary area, and averages the remaining blocks to obtain the representative luminance. By calculating, the luminance information excluding the peculiar information can be obtained, and an appropriate luminance ratio can be obtained.

Further, the ratio detecting means calculates the difference between the representative luminance and the luminance of a block in an arbitrary area composed of blocks other than an arbitrary area composed of predetermined blocks determined according to the distance between the objects and the relationship between the objects. By comparing the ratios and calculating the ratio of blocks satisfying the threshold condition in an arbitrary area composed of predetermined blocks, the accuracy of backlight or over-direct light can be accurately determined.

Further, the correction amount generation means generates a correction amount according to each ratio in an arbitrary area composed of the predetermined block from a ratio of blocks satisfying the threshold condition in an arbitrary area composed of the predetermined block. Various back light and over-order light can be handled.

Further, the correction amount generating means changes the correction amount according to the comparison result by comparing the ratio of blocks satisfying the threshold condition in an arbitrary area composed of the predetermined block with a predetermined reference value, thereby providing backlight. And the degree of over-direct light.

Further, the correction amount generating means generates a correction amount based on a change in a ratio in an arbitrary area composed of blocks satisfying the respective threshold conditions by using a plurality of predetermined threshold conditions, so that backlight or excessive light is generated. It can correspond to the degree of direct light,
Appropriate exposure control can be performed.

An arbitrary area composed of predetermined blocks is
When the brightness is equal to or greater than a predetermined threshold, it is considered that there is no difference between the distances of the subjects and that the distance is single, and when the distance of the subjects is far, the area is set smaller than a predetermined value, and the When the subject is regarded as a single object without being located on the near side, and when the subject is mixed on the far side and the near side, the area is set to a predetermined size larger than a predetermined value. This can be reflected by the size of the subject, and the accuracy of backlight or over-direct light can be accurately determined.

According to another exposure control method of the present invention, a part or the whole of a screen is divided into a plurality of blocks, a luminance level obtained from a predetermined block is set as a predetermined reference level, and an average luminance value of each block as a whole. Is determined to be within a range of a predetermined reference level, and in accordance with the distance between the objects and the relationship between the objects, the luminance in an arbitrary area composed of the predetermined blocks is calculated as the representative luminance. A ratio of blocks satisfying the threshold condition is obtained, a correction amount is generated from the ratio, an exposure control amount is determined based on the correction amount, and exposure control is performed based on the exposure control amount. Therefore, according to the present invention, it is possible to perform more appropriate exposure control for backlight or over-directed light.

A medium according to still another invention has a function of dividing a part or the whole of a screen into a plurality of blocks, a luminance level obtained from a predetermined block as a predetermined reference level, and an average of all blocks. A function of determining whether or not the luminance value is within a predetermined reference level range, and a function of calculating the luminance in an arbitrary area composed of a predetermined block as a representative luminance according to the distance between the objects and the relationship between the objects. And a function of calculating a ratio of blocks satisfying the threshold condition in an arbitrary area, a function of generating a correction amount from the ratio, and determining an exposure control amount based on the correction amount and performing exposure based on the exposure control amount. An exposure control program including a control function is recorded. Therefore, by executing the exposure control program recorded on the medium of the present invention by a computer, it becomes possible to perform more appropriate exposure control for backlight or over-direct light.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an exposure control circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a block division area according to the first embodiment.

FIG. 3 is a flowchart illustrating a state detection process according to the first embodiment.

FIG. 4 is a characteristic diagram illustrating a relationship between a focus lens position and focus information in the first embodiment.

FIG. 5 is a characteristic diagram showing a relationship between an area weight and a ratio.

FIG. 6 is a diagram illustrating a change in a threshold value in an image in a backlight state according to the first embodiment.

FIG. 7 is a block diagram illustrating a configuration of an exposure control circuit according to a second embodiment of the present invention.

FIG. 8 is a diagram showing an image in a backlight state in a conventional example.

FIG. 9 is a diagram showing an example of block division of a two-dimensional image according to a conventional example.

[Explanation of symbols]

 Reference Signs List 18 block generation circuit 19 state detection circuit 20 representative luminance calculation circuit 21 ratio detection circuit 22 correction amount generation circuit 23 exposure control circuit

Claims (15)

[Claims] 1. A digital still video camera that converts the luminance of a subject into an electric signal using a solid-state imaging device and records and / or reproduces the image information based on the electric signal, the screen including a subject and a background. In the exposure control method for adjusting the exposure state, a part or the whole of a screen is divided into a plurality of blocks, and a luminance level obtained from a predetermined block is set as a predetermined reference level, and an average luminance value of each block as a whole is predetermined. It is determined whether or not it is within the range of the reference level, and the luminance in an arbitrary area composed of a predetermined block is calculated as the representative luminance in accordance with the distance between the objects and the relationship between the objects. Calculates the amount of block that satisfies the equation, generates a correction amount from the ratio, determines the exposure control amount based on the correction amount, and An exposure control method comprising: 2. The representative luminance is calculated by excluding each block having high luminance equal to or higher than a predetermined upper threshold and low luminance lower than or equal to a predetermined lower threshold in the arbitrary area, and averaging the remaining blocks. 2. The exposure control method according to 1. 3. A comparison is made between a ratio of the representative luminance to a luminance of a block in an arbitrary area composed of blocks other than an arbitrary area composed of predetermined blocks determined according to a distance between the objects and a relation between the objects. 2. The exposure control method according to claim 1, wherein a ratio of blocks satisfying a threshold condition in an arbitrary area including the predetermined block is calculated. 4. The exposure according to claim 1, wherein a correction amount is generated in accordance with a ratio of blocks satisfying a threshold condition in an arbitrary area composed of the predetermined blocks, in accordance with each ratio in an arbitrary area composed of the predetermined blocks. Control method. 5. The exposure control method according to claim 1, wherein a ratio of blocks satisfying a threshold condition in an arbitrary area including the predetermined block is compared with a predetermined reference value, and the correction amount is changed according to a comparison result. 6. The exposure control method according to claim 1, wherein, using a plurality of predetermined threshold conditions, a correction amount is generated based on a change in a ratio in an arbitrary area composed of blocks satisfying each threshold condition. 7. An arbitrary area composed of the predetermined block, when the brightness is equal to or more than a predetermined threshold value, there is no difference in subject distance and it is regarded as a single object, and the subject distance is on the far side. When the area is set smaller than the predetermined value, the distance between the subjects is not different and the object is regarded as a single and the subject is on the near side, and when the subject is mixed on the far side and the near side, 2. The exposure control method according to claim 1, wherein the area is set to a predetermined size larger than a predetermined value. 8. A digital still video camera that converts the luminance of a subject into an electric signal by a computer using a solid-state imaging device, and records and / or reproduces the image information based on the electric signal. A medium for recording an exposure control program for adjusting an exposure state of a screen, comprising a function of dividing a part or the whole of the screen into a plurality of blocks, and a method of dividing a luminance level obtained from a predetermined block into a predetermined reference level. And a function of determining whether or not the average luminance value of each block is within a range of a predetermined reference level, and the luminance of an arbitrary area formed of the predetermined block according to the distance between the objects and the relationship between the objects. Is calculated as a representative luminance, a function of calculating the ratio of blocks satisfying the threshold condition in an arbitrary area, and a function of calculating the ratio And generating a correction amount, a medium recording the exposure control program including the function of the correction amount determines the amount of exposure control on the basis of the exposure control is performed based on the amount of exposure control. 9. A digital still video camera that converts the luminance of a subject into an electric signal using a solid-state imaging device and records and / or reproduces the image information based on the electric signal, wherein the screen includes a subject, a background, and the like. An exposure control device that automatically adjusts an exposure state of a block; a block generation unit that divides a part or the whole of a screen into a plurality of blocks; and a luminance level obtained from a predetermined block is set as a predetermined reference level. Means for determining whether or not the entire average brightness value is within a range of a predetermined reference level; and, based on the distance between the objects and the relationship between the objects, the luminance in an arbitrary area formed of predetermined blocks is set as the representative luminance. A representative luminance calculating means for calculating; a ratio detecting means for calculating a ratio of blocks satisfying a threshold condition in an arbitrary area; And an exposure control program for determining an exposure control amount based on the correction amount and performing exposure control based on the exposure control amount. Medium. 10. The representative luminance calculating means excludes each block having a high luminance equal to or higher than a predetermined upper threshold and a low luminance equal to or lower than a predetermined lower threshold in the arbitrary area, averages the remaining blocks, and averages the remaining blocks. 10. The representative brightness is calculated.
Exposure control device as described. 11. The ratio detecting means includes: a luminance of a block in an arbitrary area including blocks other than an arbitrary area including a predetermined block determined according to a distance between objects and a relationship between objects; 10. The exposure control apparatus according to claim 9, wherein a ratio of blocks satisfying a threshold condition in an arbitrary area including the predetermined block is calculated by comparing the ratio of the predetermined block with the threshold. 12. The correction amount generating means generates a correction amount according to a ratio of blocks satisfying a threshold condition in an arbitrary area composed of the predetermined blocks according to each ratio in an arbitrary area composed of the predetermined blocks. The exposure control device according to claim 9. 13. The correction amount generation unit, wherein a ratio of blocks satisfying a threshold condition in an arbitrary area including the predetermined block is compared with a predetermined reference value, and the correction amount is changed according to a comparison result. 9. The exposure control method according to item 9. 14. The correction amount generation unit according to claim 9, wherein the correction amount generation unit generates the correction amount based on a change in a ratio in an arbitrary area including blocks satisfying the threshold conditions, using a plurality of predetermined threshold conditions. Exposure control device. 15. An arbitrary area composed of the predetermined block, when the brightness is equal to or more than a predetermined threshold value, there is no difference in subject distance and it is regarded as a single object, and the subject distance is on the far side. When the area is set smaller than the predetermined value, the distance between the subjects is not different and the object is regarded as a single and the subject is on the near side, and when the subject is mixed on the far side and the near side, 10. The exposure control apparatus according to claim 9, wherein the area is set to a predetermined size larger than a predetermined value.