JP2006319901A - Electronic camera and image processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable correction for obtaining an image to be subjected to proper exposure even if there is a portion reaching a saturation level in an image generated by image capturing. <P>SOLUTION: An electronic camera comprises: a photometric section for performing photometry upon a subject field; an imaging section for generating an image by imaging the subject field after determining an exposure based on a photometric value of the photometric section; an arithmetic section for calculating a correction value to be used for correcting the image on the basis of a ratio of an image output value of a portion corresponding to a predetermined area of the subject field in the image generated by the imaging section and a target image output value of the predetermined area, and of a difference between a photometric value detected by the photometric section and determining the exposure and a maximum luminance value of the predetermined area; and a correction section for correcting the image on the basis of the correction value operated by the arithmetic section. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electronic camera that captures an object scene and generates an image, and an image processing program for performing image processing on an image to be processed.

Conventionally, in an electronic camera, the luminance of the object scene is detected by a photometric element or the like, and conditions such as exposure and aperture at the time of shooting are determined based on the result. And each part of an electronic camera is controlled so that the determined conditions are implement | achieved. However, such control may cause an error and may not be controlled according to the determined condition.
If it is not controlled according to the conditions, an image with proper exposure cannot be obtained.

In the invention of Patent Document 1, in order to solve such a problem, the image is corrected based on the ratio between the luminance value of the portion corresponding to the photometric area and the predetermined target luminance value in the captured image. is doing.
JP 2005-57358 A

However, in the above-described method, when there is a portion that has reached a saturation level in an image generated by imaging, an accurate correction value cannot be obtained because the exact luminance of that portion is unknown.
The present invention has been made in view of the above problems, and an electronic camera that enables correction to obtain an image with an appropriate exposure even when an image generated by imaging has a portion reaching a saturation level. An object of the present invention is to provide an image processing program.

  An electronic camera according to the present invention includes a photometric unit that performs photometry of an object scene, an imaging unit that determines an exposure amount based on a photometric value obtained by the photometric unit, images the object field, and generates an image, and the imaging A ratio between an image output value of a portion corresponding to a predetermined area of the object scene and a target image output value of the predetermined area, and the exposure amount detected by the photometry section. Based on the difference between the determined photometric value and the maximum luminance value of the predetermined area, a calculation unit for calculating a correction value used when correcting the image, and the correction value calculated by the calculation unit based on the correction value. A correction unit that corrects the image.

Preferably, the calculation unit calculates the correction value such that the degree of correction by the correction unit decreases as the difference between the photometric value for determining the exposure amount and the maximum luminance value increases. May be.
In addition, the image processing program of the present invention includes an image to be processed, information on a partial area of the image, an acquisition procedure for obtaining a photometric value of the object scene when the image is captured, The ratio between the image output value of the partial area of the image and the target image output value of the partial area, and among the photometric values, a photometric value for determining an exposure amount at the time of capturing the image, A calculation procedure for calculating a correction value used when correcting the image based on a difference from a maximum luminance value of a portion corresponding to the partial region, and the processing based on the correction value calculated in the calculation procedure And causing the computer to execute a correction procedure for correcting the target image.

  Preferably, in the calculation procedure, the correction value is calculated so that the degree of correction decreases as the difference between the photometric value for determining the exposure amount and the maximum luminance value increases. good.

  According to the electronic camera and the image processing apparatus of the present invention, it is possible to perform correction for obtaining an image with appropriate exposure even when an image generated by imaging includes a portion that has reached a saturation level.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an electronic camera 100 according to the first embodiment.
The electronic camera 100 includes a camera body 101 and a photographing lens 102. The taking lens 102 is detachable from the camera body 101 and includes a lens 1 and an aperture stop 2 therein. The camera body 101 can also be attached and detached with a photographic lens other than the photographic lens 102.

The camera body 101 is a single-lens reflex camera, and includes a quick return mirror 3, a diffusion screen (focus plate) 4, a condenser lens 5, a pentaprism 6, an eyepiece lens 7, a photometric prism 8, a photometric lens 9, and a photometric element 10. A shutter 11 and an image sensor 12.
When not photographing, that is, when photographing is not performed, the quick return mirror 3 is disposed at an angle of 45 ° with respect to the optical axis, as shown in FIG. The light beam that has passed through the lens 1 and the aperture stop 2 with the photographing lens 102 mounted on the camera body 101 is reflected by the quick return mirror 3 and passes through the diffusion screen 4, the condenser lens 5, and the pentaprism 6. Guided to eyepiece 7. A part of the light beam diffused by the diffusing screen 4 is guided to the photometric element 10 through the condenser lens 5, the pentaprism 6, the photometric prism 8, and the photometric lens 9.

On the other hand, at the time of photographing, the quick return mirror 3 is retracted to the position indicated by the broken line, the shutter 11 is opened, and the light flux from the photographing lens 102 is guided to the image sensor 12. The imaging element 12 is a light receiving element whose sensitivity is variable, such as a CCD (Charge Coupled Device).
FIG. 2 is a functional block diagram of the electronic camera 100.
The electronic camera 100 includes a photometry unit 13, a calculation unit 14, a control unit 15, an operation unit 16, an imaging unit 17, an image correction unit 18, and a memory unit 19.

  The photometric unit 13 includes the photometric prism 8, the photometric lens 9, and the photometric element 10 shown in FIG. The calculation unit 14 calculates parameters and the like for controlling each unit based on outputs from the photometry unit 13 and an imaging unit 17 described later (details will be described later), and the photometry unit 13, the control unit 15, and the image correction unit. The calculation result is output to 18. The calculation unit 14 also determines whether there is image data that has reached the dynamic range (saturation level) in the image to be corrected (details will be described later).

  Further, the control unit 15 drives the aperture stop 2, the quick return mirror 3, and the shutter 11 according to the calculation result of the calculation unit 14. The operation unit 16 includes a release button (not shown), a setting button (such as an exposure correction button and an AE lock button for fixing the exposure value) for setting an exposure correction value by a user (details will be described later), and the like. The output of the operation unit 16 is connected to the calculation unit 14.

  Further, the imaging unit 17 includes the imaging element 12 of FIG. 1, images the object scene via the photographing lens 102, and outputs image data to the image correction unit 18. The imaging unit 17 also outputs image data obtained by imaging to the calculation unit 14. The image correction unit 18 corrects the image data output from the imaging unit 17 according to the calculation result of the calculation unit 14 (details will be described later), and outputs the corrected image data to the memory unit 19.

The memory unit 19 is a recording medium such as a memory card (card-shaped removable memory), and records the image data corrected by the image correcting unit 18. The memory unit 19 may be a built-in memory.
Incidentally, the photometric element 10 included in the photometric unit 13 is a light receiving element such as an SPD (Silicon Photo Diode) or a CCD, and is a divided photometric sensor shown in FIG. The photometric element 10 divides substantially the entire surface of the object scene into 25 areas and performs photometry, and detects the luminance values BV (1) to BV (25) of the respective areas. The electronic camera 100 has three photometry modes for photometry using such a photometry element 10. The three metering modes are a central partial metering mode, a spot metering mode, and a multi-segment metering mode. These metering modes are set by the user via the operation unit 16.

The operation at the time of shooting of the electronic camera 100 having the above-described configuration will be described with reference to the flowchart shown in FIG. The series of operations in the flowchart of FIG. 4 is started when a release button (not shown) is half-pressed (pressed halfway).
When the release button (not shown) is half-pressed by the user, in step S1, the electronic camera 100 turns on the power of the photometry element 10 of the photometry unit 13 and performs a predetermined initialization operation.

In step S <b> 2, the photometric element 10 of the photometric unit 13 measures the object field via the photometric prism 8 and the photometric lens 9 to detect luminance. At this time, the photometry unit 13 performs photometry in an area corresponding to the photometry mode set by the user and a correction reference area described later.
When the central partial metering mode is set by the user, the metering element 10 of the metering unit 13 detects the luminance values BV (1) to BV (9) with the regions 1 to 9 corresponding to the substantially center in FIG. To do. When the spot metering mode is set by the user, the metering unit 13 detects the brightness value BV (5) with the center spot region 5 in FIG. Further, when the multi-division photometry mode is set by the user, the photometry element 10 of the photometry unit 13 sets the luminance values BV (1) to BV (25) as the photometry targets in the areas 1 to 25 on the entire surface of FIG. To detect.

  Further, the photometric element 10 of the photometric unit 13 uses the areas 1 to 9, 13, 14, 17, 18, 21, and 22 in FIG. 3 as photometric objects as the above-described correction reference areas, and luminance values BV (1) to BV. (9), BV (13), BV (14), BV (17), BV (18), BV (21), BV (22) are detected. In addition, when each photometry mode is set, which area is set as a photometric target and which correction correction area is set is not limited to this example.

In step S <b> 3, the calculation unit 14 calculates the exposure control luminance value BVexp based on the luminance value detected by the photometric unit 13 according to the photometric mode and the exposure correction value or bracketing value set in the operation unit 16 by the user. calculate.
That is, when the central partial photometry mode is set by the user, the calculation unit 14 calculates the exposure control luminance value BVcw in the central partial photometry mode based on the luminance values BV (1) to BV (9). When the spot photometry mode is set, the calculation unit 14 calculates an exposure control luminance value BVsp in the spot photometry mode based on the luminance value BV (5). Further, when the multi-division photometry mode is set, the calculation unit 14 calculates an exposure control luminance value BVa in the multi-division photometry mode based on the luminance values BV (1) to BV (25). That is, when the central partial metering mode is set by the user, the exposure control luminance value BVexp = BVcw− (BVec + BVbkt), and when the spot metering mode is set, the exposure control luminance value BVexp = BVsp− (BVec + BVbkt). Thus, when the multi-segment photometry mode is set, the exposure control luminance value BVexp = BVa− (BVec + BVbkt).

  BVec is a manual exposure correction value set by the user via the operation unit 16. By setting the manual exposure correction value BVec to +1, -2, for example, the user can perform exposure correction that is intentionally shifted from appropriate exposure, such as brightening and darkening. BVbkt is a bracketing value set by the user via the operation unit 16. The user sets the bracketing value BVbkt to, for example, “3 shots per step”, and executes continuous shooting, so that “appropriate”, “predetermined amount of darkness”, and “predetermined amount of brightening” "You can shoot with different exposures step by step."

The specific calculation method of these exposure control luminance values (BVcw, BVsp, BVa) is the same as the method disclosed in, for example, JP-A-9-281543 and JP-A-11-12556. Detailed description will be omitted.
In step S4, the calculation unit 14 calculates a corrected reference area luminance value BVref that is an average luminance value of the corrected reference area detected by the photometry unit 13.

  In step S5, the calculation unit 14 calculates an exposure control parameter. The exposure control parameter refers to the shutter speed, the aperture value, and the sensitivity of the image sensor 12. The computing unit 14 calculates an exposure control parameter based on the exposure control luminance value BVexp calculated in step S3. The computing unit 14 is provided with an arithmetic expression for calculating the shutter speed, the aperture value, and the sensitivity of the image sensor 12 based on the exposure control luminance value BVexp. Then, the calculation unit 14 outputs the calculated shutter speed, aperture value, and sensitivity of the image sensor 12 to the control unit 15 as exposure control parameters.

In step S6, the calculation unit 14 determines whether or not a release button (not shown) has been fully pressed (completely pressed) by the user. If not, the process proceeds to step S7. If so, the process proceeds to step S11.
When the release button (not shown) is not fully pressed by the user, in step S7, the calculation unit 14 calculates a photometry unit control parameter.

The photometric unit control parameter is a photometric condition in the photometric unit 13 and indicates an amplifier gain when the photometric element 10 of the photometric unit 13 is an SPD, and an amplifier gain and an accumulation time when the photometric element is a CCD. When the calculation unit 14 calculates the photometry unit control parameter, the calculation unit 14 outputs the calculated photometry unit control parameter to the photometry unit 13.
In step S7, the calculation unit 14 determines the photometric conditions for the next photometry based on the photometric result of step S2. Therefore, the photometry unit 13 can perform optimal photometry that is more suitable for the situation.

In step S8, the calculation unit 14 determines whether or not an AE lock button (not shown) of the operation unit 16 is set to ON by the user, and proceeds to step S9 if it is set to ON. On the other hand, if the AE lock button is not set to ON, the process returns to step S2, and the processes after step S2 are performed again.
When the AE lock button (not shown) is set to ON by the user, in step S9, the photometry element 10 of the photometry unit 13 measures the object scene and detects the luminance in the same manner as in step S2. However, in step S9, the photometric element 10 of the photometric unit 13 sets the above-described correction reference region as a photometric target, and luminance values BV (1) to BV (9), BV (13), BV (14), BV ( 17), BV (18), BV (21), and BV (22) are detected.

In step S10, the calculation unit 14 calculates a corrected reference region luminance value BVref based on the luminance value of the corrected reference region detected by the photometry unit 13, as in step S4. When the corrected reference area luminance value BVref is calculated, the process returns to step S6, and the processes after step S6 are performed again.
When the AE lock button (not shown) is set to ON by the user (YES in step S8), the electronic camera 100 performs photometry and correction reference area in the correction reference area until the release button is fully pressed (YES in step S6). The calculation of the luminance value BVref and the calculation of the photometry unit control parameter are repeated. If the AE lock button (not shown) is not set to ON by the user (NO in step S8), refer to the calculation and correction of photometry and exposure control brightness value BVexp until the release button is fully pressed (YES in step S6). The calculation of the area luminance value BVref, the calculation of the exposure control parameter, and the calculation of the photometry unit control parameter are repeated. When the release button (not shown) is fully pressed by the user, the process proceeds to step S11.

When a release button (not shown) is fully pressed by the user, in step S11, the control unit 15 and the imaging unit 17 capture an image of the object scene.
The control unit 15 controls the aperture stop 2, the shutter 11, the quick return mirror 3, and the imaging unit 17 based on the shutter speed, the aperture value, and the sensitivity of the imaging device 12 calculated by the calculation unit 14, and the imaging unit 17 , Image the scene.

Here, it is considered that an error has occurred in the control of the aperture stop 2 and the shutter 11 by the control unit 15. Therefore, in order to improve this error, in step S12, the calculation unit 14 and the image correction unit 18 perform digital gain processing described later.
FIG. 5 is a diagram illustrating the imaging element 12 of the imaging unit 17. Each square in FIG. 5 corresponds to a pixel of the image sensor 12. Then, image data of a red component (R component), a green component (G component), and a blue component (B component) is output from each pixel to the image correction unit 18.

First, the calculation unit 14 obtains the luminance value Y of each pixel using the following equation.
Y [i, j] = Kr * Dr [i, j] + Kg * Dg [i, j] + Kb * Db [i, j] (Equation 1)
In Expression 1, i and j represent pixel numbers, Dr represents R component image data, Dg represents G component image data, and Db represents B component image data. Kr, Kg, and Kb are predetermined coefficients for obtaining a luminance value from the image data.

Next, the calculating part 14 calculates | requires target luminance output correction coefficient HT using following Formula.
HT = 2 ^ (BVref−BVexp) (Formula 2)
Next, the calculating part 14 calculates | requires imaging | photography time target value TgY using following Formula.
TgY = TgS × HT (Formula 3)
In Expression 3, the shooting target value TgY corresponds to the correction reference region of the photometry unit 13 among the image data output by the imaging unit 17 when there is no control error of the aperture stop 2 and the shutter 11 by the control unit 15. This corresponds to the average luminance output of the partial image data. Further, TgS is a reference target value that is set in advance so that a uniformly gray (halftone) subject is imaged in advance, and image data obtained by this imaging becomes preferable gray (reproduced as halftone). is there. In addition, the electronic camera 100 calculates the gray subject based on the corrected reference area luminance value BVref with no control error, the manual exposure correction value BVec = 0, the bracketing value BVbkt = 0, and the correction reference area luminance value BVref. When imaging is performed under conditions of exposure control parameters (exposure control parameters will be described later), the image sensor output without digital gain correction according to the present invention is adjusted to be the reference target value TgS.

Furthermore, the calculating part 14 calculates | requires exposure error amount ExpErr using following Formula.
ExpErr = TgY / AveYref (Formula 4)
In Equation 4, AveYref is the average luminance output of the image data of the portion corresponding to the correction reference area of the photometry unit 13 among the image data output by the imaging unit 17, and is obtained using the following equation.

AveYref = (ΣY [i, j]) / [(x2−x1 + 1) × (y2−y1 + 1)] (Formula 5)
However, in Formula 5, i = x1 to x2 and j = y1 to y2. The parts i = x1 to x2 and j = y1 to y2 are corrected reference areas (areas 1 to 9, 13, 14, 17, 18, 21, and 22 in FIG. 3) of the image data output by the imaging unit 17. The average of the luminance output of the image data of this part is calculated by Equation 5.

Next, the calculating part 14 calculates | requires digital gain correction coefficient CT using following Formula.
CT = [(ExpErr−1) × AP + 1] (Formula 6)
In Equation 6, AP indicates a correction contribution rate and takes a value of 0 to 1 (details will be described later).
And the calculating part 14 correct | amends the image data output from the imaging part 17 using following Formula.

DA = DB × CT (Expression 7)
In Expression 7, DA indicates image data after correction, and DB indicates image data output from the imaging unit 17 (before correction).
When the correction contribution rate AP is larger than 0 and correction is performed using Equation 7, when the exposure error amount ExpErr is larger than 1, that is, when the digital gain correction coefficient CT is larger than 1, the entire image is brightened. It is possible to correct in the direction (the direction in which the output level in the image is increased). On the other hand, when the exposure error amount ExpErr is smaller than 1, that is, when the digital gain correction coefficient CT is smaller than 1, the entire image can be corrected in a darkening direction (a direction in which the output level in the image is reduced).

  However, if the digital gain correction coefficient CT is too large, the noise component included in the image data DB before correction is also amplified, and as a result, the image after correction becomes an image with noticeable noise. Accordingly, a limit value α may be provided for the digital gain correction coefficient CT so that the digital gain correction coefficient CT ≦ α. The limit value α is a digital gain value that allows noise, and is obtained in advance through experiments or the like.

  Further, when the image data Dr, Dg, Db has reached the dynamic range, if correction based on the exposure error amount ExpErr smaller than 1 is performed, a false color may occur in the corrected image. For example, when a red flower is photographed as a subject and overexposure occurs in part of the image due to overexposure, all the image data Dr, Dg, Db corresponding to the overexposure part reaches the dynamic range. ing. Then, when this image data is corrected based on an exposure error amount ExpErr smaller than 1 (that is, correction in a direction to reduce the output level in the image), all the corrected image data Dr, Dg, Db are obtained. The value is as small as the dynamic range. This means that it is corrected to light gray, and a part of the red flower is corrected to light gray. Therefore, it is detected whether there is image data that has reached the dynamic range in the image to be corrected. If there is image data that has reached the dynamic range and the exposure error amount ExpErr is smaller than 1, the correction contribution rate AP = 0 may be set (that is, correction is prohibited). In addition, when the exposure error amount ExpErr is smaller than 1, the correction contribution ratio AP = 0, thereby simplifying the process, reducing the load on the control unit 15 and the calculation unit 14, and reducing the processing time. Anyway.

  Furthermore, even if the exposure error amount ExpErr is larger than 1, if there is image data that has reached the dynamic range in the correction reference area, the average luminance output AveYref becomes a value smaller than the original luminance of the subject. Therefore, the digital gain correction coefficient CT becomes larger than an appropriate value. In such a case, the correction contribution rate AP may be reduced. For example, the correction contribution rate AP is set to the luminance values BV (1) to BV (9), BV (13), BV (14), BV (17), BV (18) in the correction reference area detected by the photometry unit 13. ), BV (21), BV (22) and a function of the difference between the exposure control luminance value BVexp. Therefore, the calculation unit 14 calculates the difference dBV using the following equation.

dBV = MAX {Luminance value BV (i)} in the corrected reference area} −BVexp (Expression 8)
When the difference dBV <β calculated using Equation 8 is set, the correction contribution rate AP = 1, and when dBV ≧ β, the correction contribution rate AP is calculated using the following equation.
AP = 1−dBV × γ (Equation 9)
FIG. 6 shows the relationship between the difference dBV and the correction contribution rate AP. Here, β and γ are positive predetermined values. When exposure control is performed based on the exposure control brightness value BVexp, an achromatic subject having the same brightness as the exposure control brightness value BVexp is expressed in gray (halftone). That is, the brighter the subject having the maximum luminance value in the correction reference area is brighter than the exposure control luminance value BVexp, the higher the possibility of saturation. Therefore, when the difference dBV is large, the correction contribution ratio AP may be reduced.

As described above, optimal digital gain processing can be performed by setting the correction contribution rate AP in accordance with the shooting situation.
When the digital gain processing of the image data is performed as described above, in step S13, the memory unit 19 records the image data corrected by the image correction unit 18, and ends a series of processing.

  As described above, according to the first embodiment, the object scene is photometrically measured, the exposure amount is determined based on the photometric value based on the photometry result, the object scene is imaged, and an image is generated. And the photometric value which determined the ratio of the image output value of the part corresponding to the predetermined area | region of a scene and the target image output value of a predetermined area among the images produced | generated by imaging, and the exposure amount detected by photometry A correction value used when correcting the image is calculated based on the difference between the maximum brightness value of the predetermined area and the image, and the image is corrected based on the correction value. Therefore, even when there is a portion that has reached the saturation level in the image generated by imaging, it is possible to perform correction for obtaining an image with appropriate exposure.

Further, according to the first embodiment, the correction value is calculated so that the degree of correction becomes smaller as the difference between the photometric value for which the exposure amount is determined and the maximum luminance value is larger. Therefore, it is possible to make corrections for obtaining an image with appropriate exposure according to the shooting situation.
In the first embodiment, an example in which the fixed reference target value TgS is used has been described. However, for example, the reference target value TgS may be appropriately changed according to a white balance mode or the like. Thus, more appropriate correction can be performed by appropriately changing the reference target value TgS.

  In the first embodiment, the automatic exposure mode in which the electronic camera 100 automatically performs exposure control has been described as an example. However, the present invention is similarly applied to a so-called manual exposure mode in which a user performs exposure setting. Can be applied. In the case of the manual exposure mode, the exposure control brightness value BVexp is not calculated based on the brightness values BV (1) to BV (25) obtained by the photometry unit 13, but the shutter speed, aperture value, and It may be calculated from the sensitivity of the image sensor 12. By calculating the exposure control luminance value BVexp in this way, an image with appropriate brightness can be easily obtained while reflecting the user's intention. However, in the bulb mode, since the shutter speed is not known in advance, the exposure control luminance value BVexp cannot be calculated. Therefore, the correction may be prohibited by setting the correction contribution ratio AP = 0.

<< Second Embodiment >>
The second embodiment of the present invention will be described below with reference to the drawings. In addition, about the functional block similar to 1st Embodiment, it demonstrates using the code | symbol similar to 1st Embodiment below.
FIG. 7 is a functional block diagram of a computer 200 according to the second embodiment.

As shown in FIG. 7, the computer 200 includes an image correction unit 20 and a display unit 21, and a reading unit 22 that can receive data from the outside. In the computer 200, the image processing program of the present invention is recorded in advance. The computer 200 corrects the image according to the image processing program.
In FIG. 7, a computer 200 is connected to an external electronic camera 300 via a reading unit 22.

The computer 200 acquires image data obtained by imaging from the electronic camera 300, corrects the image data in the procedure described with reference to FIG. 4 in the image correction unit 20, and displays the image data on the display unit 21. Since the specific method of correction is the same as that of the first embodiment, description thereof is omitted.
However, the computer 200 has been described with reference to FIG. 4 of the first embodiment, together with image data (image to be processed) obtained by imaging, and a photometric area in the object scene as an imaging condition when the image is captured. An imaging condition capable of performing correction similar to the correction is acquired.

Note that the imaging conditions may be recorded as incidental information of image data using a file format such as EXIF, for example. Further, the computer 200 may acquire an image to be processed not from the electronic camera 300 but from a recording medium such as a memory card.
As described above, according to the second embodiment, the same effect as that of the first embodiment can be obtained.

  In the second embodiment, an example is shown in which correction similar to that in the flowchart of FIG. 4 of the first embodiment is performed. However, only a part of each step in the flowchart of FIG. .

It is a schematic block diagram of the electronic camera of 1st Embodiment. It is a functional block diagram of the electronic camera of 1st Embodiment. It is a figure explaining a photometry element. It is a flowchart which shows operation | movement of the electronic camera of 1st Embodiment. It is a figure which shows the image pick-up element of an imaging part. It is a figure which shows the relationship between difference dBV and correction | amendment contribution rate AP. It is a functional block diagram of a computer of a 2nd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, Photometry element 12, Imaging element 13, Photometry part 14, Calculation part 15, Control part 16, Operation part 17, Imaging part 18, Image correction part 100/300, Electronic camera 101, Camera body 200, Computer

Claims (4)

A metering unit for metering the object scene;
An imaging unit that determines an exposure amount based on a photometric value obtained by the photometric unit, images the object scene, and generates an image;
Of the image generated by the imaging unit, a ratio between an image output value of a portion corresponding to a predetermined region of the object scene and a target image output value of the predetermined region, and the exposure detected by the photometric unit A calculation unit that calculates a correction value to be used when correcting the image based on a difference between the photometric value for which the amount is determined and the maximum luminance value of the predetermined area;
An electronic camera comprising: a correction unit that corrects the image based on the correction value calculated by the calculation unit. The electronic camera according to claim 1,
The calculation unit calculates the correction value so that the degree of correction by the correction unit decreases as the difference between the photometric value for determining the exposure amount and the maximum luminance value increases. . Along with the image to be processed, the acquisition procedure for acquiring the partial area information of the image and the photometric value of the object scene when the image is captured,
Photometry for determining the ratio of the image output value of the partial area to the target image output value of the partial area of the image to be processed and the exposure amount at the time of imaging of the image among the photometric values A calculation procedure for calculating a correction value to be used when correcting the image based on a difference between a value and a maximum luminance value of a portion corresponding to the partial region;
An image processing program for causing a computer to execute a correction procedure for correcting the image to be processed based on the correction value calculated in the calculation procedure. The image processing program according to claim 3.
In the calculation procedure, the correction value is calculated so that the degree of correction decreases as the difference between the photometric value for determining the exposure amount and the maximum luminance value increases.

Images