JP2006084863A - Electronic camera and image processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic camera and an image processing program in which an image of suitable brightness can be simply obtained without increasing the capacity of a memory. <P>SOLUTION: The electronic camera comprises an image pickup part for picking up a subject field and generating an image; an operation part for calculating a correction value to be used for correcting the image on the basis of the ratio of a luminance value of a part corresponding to a prescribed area of the subject field out of the picked-up image to a target luminance value of the prescribed area; and a correction part for correcting the image on the basis of the correction value calculated by the operation part. The operation part calculates the correction value so that the degree of correction by the correction part is reduced in inverse proportion to the number of image data having reached a saturation level in a part corresponding to the prescribed area of the subject field. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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, whiteout or blackout occurs in the obtained image.

In the invention of Patent Document 1, in order to solve such a problem, an error amount is measured and stored in advance for each assumed aperture value, and the error amount for each aperture value is read during control, and the error amount is obtained. Accordingly, the shutter speed and the gain in the image sensor are corrected.
JP 2002-330334 A

However, as described above, in order to store the error amount for each aperture value, it takes time to measure the error amount in advance, and a memory for storing it is also necessary. Further, in this case, since each part of the diaphragm mechanism part changes with time due to wear or the like, the stored error amount also changes and becomes meaningless.
In addition, when applying the above-described invention of Patent Document 1 to an interchangeable lens electronic camera, an error amount must be measured and stored in advance for each lens and each aperture value. In this case, in order to measure and store all possible interchangeable lenses in advance, the above-described effort is further required, and the capacity of the memory to be stored increases. Further, when the interchangeable lens does not include a CPU, the electronic camera cannot recognize what interchangeable lens is mounted.

  The present invention has been made in view of the above problems, and an object thereof is to provide an electronic camera and an image processing program capable of easily obtaining an image with appropriate brightness without increasing the capacity of a memory. To do.

  The electronic camera according to claim 1, an imaging unit that images an object scene to generate an image, a luminance value of a portion corresponding to a predetermined region of the object scene, of the captured image, A calculation unit that calculates a correction value used when correcting the image based on a ratio to a target luminance value of a predetermined area, and a correction unit that corrects the image based on the correction value calculated by the calculation unit The calculation unit reduces the degree of correction by the correction unit as the number of image data that reaches a saturation level increases in a portion of the image corresponding to the predetermined area of the object scene. Thus, the correction value is calculated as described above.

  The electronic camera according to claim 2, an imaging unit that images an object scene to generate an image, a luminance value of a portion corresponding to a predetermined area of the object scene, of the captured image, A calculation unit that calculates a correction value used when correcting the image based on a ratio to a target luminance value of a predetermined area, and a correction unit that corrects the image based on the correction value calculated by the calculation unit And the calculation unit corrects the correction so that the degree of correction decreases as the difference between the maximum luminance value and the minimum luminance value of the portion corresponding to the predetermined area of the object field increases. A value is calculated.

  The electronic camera according to claim 3 is determined according to a selection unit that selects one shooting scene from a plurality of predetermined shooting scenes, and the one shooting scene selected by the selection unit. An imaging unit that captures an image of the scene according to the shooting conditions and generates an image; a luminance value of a portion of the captured image corresponding to a predetermined area of the scene; and a target luminance of the predetermined area Based on the ratio to the value and the one shooting scene selected by the selection unit, a calculation unit that calculates a correction value used when correcting the image, and the correction value calculated by the calculation unit And a correction unit for correcting the image.

An electronic camera according to a fourth aspect of the invention is the electronic camera according to any one of the first to third aspects, further comprising a photometric unit that detects luminance related to the first area and the second area of the object scene. The calculation unit calculates the target luminance value based on the luminance of the first region and the luminance of the second region.
The electronic camera according to claim 5, an imaging unit that captures an image of the scene and generates an image, a photometric unit that detects luminance of the scene, and the scene of the captured image A calculation unit that calculates a correction value to be used when correcting the image based on a ratio between a luminance value of a portion corresponding to the predetermined region and a target luminance value of the predetermined region, and is calculated by the calculation unit A correction unit that corrects the image based on the correction value, and the calculation unit includes the luminance detected by the photometry unit such that the lower the luminance in a predetermined region, the smaller the correction degree. A correction value is calculated.

  The electronic camera according to claim 6, an imaging unit that captures an image of the scene and generates an image, a photometric unit that divides a predetermined area of the scene into a plurality of areas, and detects luminance, and Based on the ratio between the luminance value of the portion corresponding to the predetermined area of the object scene in the captured image and the target luminance value of the predetermined area, a correction value used when correcting the image is calculated. And a correction unit that corrects the image based on the correction value calculated by the calculation unit, wherein the calculation unit includes the luminance for each of the plurality of areas detected by the photometry unit. The correction value is calculated so that the degree of correction decreases as the difference between the maximum luminance value and the minimum luminance value increases.

  The electronic camera according to claim 7, an imaging unit that captures an image of the scene and generates an image, a photometric unit that divides a predetermined area of the scene into a plurality of areas, and detects luminance, Based on the ratio between the luminance value of the portion corresponding to the predetermined area of the object scene in the captured image and the target luminance value of the predetermined area, a correction value used when correcting the image is calculated. And a correction unit that corrects the image based on the correction value calculated by the calculation unit, wherein the calculation unit detects the maximum luminance of the plurality of areas detected by the photometry unit. The correction value is calculated so that the degree of correction decreases as the value increases.

The electronic camera according to claim 8 is the electronic camera according to any one of claims 5 to 7, wherein the photometry unit detects luminance related to the first region and the second region of the object scene. The calculation unit calculates the target luminance value based on the luminance of the first region and the luminance of the second region.
The electronic camera according to claim 9 is the electronic camera according to claim 4 or claim 8, wherein the photometry unit divides the first area of the object scene into a plurality of areas and performs photometry. The luminance for each region is detected, and the calculation unit calculates the target luminance value based on a representative value based on the luminance for each of the plurality of regions detected by the photometry unit and the luminance of the second region. It is characterized by that.

  The image processing program according to claim 10 includes an acquisition procedure for acquiring an image to be processed, a luminance value of a portion corresponding to a predetermined area of the image to be processed, and a target luminance value of the predetermined area. A calculation procedure for calculating a correction value used when correcting the image based on the ratio; and a correction procedure for correcting the image based on the correction value calculated in the calculation procedure. In the image processing program, in the calculation procedure, the degree of correction is reduced as the number of image data that has reached a saturation level in the portion corresponding to the predetermined area of the object field increases. And calculating the correction value.

  The image processing program according to claim 11 includes an acquisition procedure for acquiring an image to be processed, a luminance value of a portion corresponding to a predetermined area of the image to be processed, and a target luminance value of the predetermined area. A calculation procedure for calculating a correction value used when correcting the image based on the ratio; and a correction procedure for correcting the image based on the correction value calculated in the calculation procedure. In the image processing program, in the calculation procedure, the degree of correction decreases as the difference between the maximum luminance value and the minimum luminance value of a portion of the image corresponding to the predetermined area of the object scene increases. And calculating the correction value.

  The image processing program according to claim 12 is determined according to a selection unit that selects one shooting scene from a plurality of predetermined shooting scenes, and the one shooting scene selected by the selection unit. An image processing program for causing a computer to perform image processing on an image generated by an imaging device including an imaging unit that captures an image of a scene in accordance with a captured imaging condition and generates an image. The acquisition procedure for acquiring the one shooting scene selected by the selection unit and the photometric area in the object scene and the luminance relating to the photometric area as an imaging condition when the image is captured together with the image, and the processing target The ratio between the luminance value of the portion corresponding to the predetermined area and the target luminance value of the predetermined area and the 1 selected by the selection unit The computer executes a calculation procedure for calculating a correction value used when correcting the image based on the shooting scene and a correction procedure for correcting the image based on the correction value calculated in the calculation procedure. It is characterized by that.

  An image processing program according to a thirteenth aspect of the present invention is the image processing program according to any one of the tenth to twelfth aspects, in the acquisition procedure, when the image is captured together with an image to be processed. The luminance relating to the photometry area and the photometry area in the object scene is acquired as an imaging condition, and in the calculation procedure, the target brightness value is determined based on the brightness of the first area and the brightness of the second area of the photometry area. It is characterized by calculating.

  The image processing program according to claim 14, an acquisition procedure for acquiring a photometric area in a subject field and a luminance relating to the photometric area as an imaging condition when the image is captured together with an image to be processed; A calculation procedure for calculating a correction value used when correcting the image based on a ratio between a luminance value of a portion corresponding to the predetermined area of the image and a target luminance value of the predetermined area; and An image processing program for causing a computer to execute a correction procedure for correcting the image based on the calculated correction value. In the calculation procedure, in the luminance region acquired in the acquisition procedure, in a predetermined region The correction value is calculated so that the degree of correction decreases as the luminance decreases.

  The image processing program according to claim 15, together with an image to be processed, an acquisition procedure for acquiring a plurality of photometric areas obtained by dividing an object scene and luminance for each of the plurality of areas as an imaging condition when the image is captured A calculation procedure for calculating a correction value to be used when correcting the image based on a ratio between a luminance value of a portion corresponding to a predetermined area of the image to be processed and a target luminance value of the predetermined area; An image processing program for causing a computer to execute a correction procedure for correcting the image based on the correction value calculated in the calculation procedure, wherein the calculation procedure includes obtaining the plural The correction value is calculated so that the degree of correction becomes smaller as the difference between the maximum luminance value and the minimum luminance value in the luminance for each region increases.

  The image processing program according to claim 16, an acquisition procedure for acquiring a plurality of photometric areas obtained by dividing the object scene and luminance for each of the plurality of areas as an imaging condition when the image is captured together with an image to be processed; A calculation procedure for calculating a correction value to be used when correcting the image based on a ratio between a luminance value of a portion corresponding to a predetermined area of the image to be processed and a target luminance value of the predetermined area; An image processing program for causing a computer to execute a correction procedure for correcting the image based on the correction value calculated in the calculation procedure, wherein the calculation procedure includes obtaining the plural The correction value is calculated so that the degree of correction decreases as the maximum luminance value of the luminance for each region increases.

The image processing program according to claim 17 is the image processing program according to any one of claims 14 to 16, wherein, in the calculation procedure, the luminance of the first region of the photometric region, The target brightness value is calculated based on the brightness of the two areas.
The image processing program according to claim 18 is the image processing program according to claim 13 or claim 17, wherein, in the obtaining step, the luminance for each of the plurality of areas obtained by dividing and metering the first area into a plurality of areas. In the calculation procedure, the target luminance value is calculated based on the representative value based on the luminance for each of the plurality of regions and the luminance of the second region.

  According to the electronic camera and the image processing apparatus of the present invention, an image with appropriate brightness can be easily obtained without increasing the capacity of the memory.

<< 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, photometric lens 9, and photometric element 10 of FIG. 1, detects the luminance of the object field, and outputs it to the computing unit 14. 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.
In addition, 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 lens 1, the aperture stop 2, the quick return mirror 3, the shutter 11, the image sensor 12, and the control unit 15 correspond to “imaging unit” in the claims. The calculation unit 14 corresponds to a “calculation unit” in the claims, and the image correction unit 18 corresponds to a “correction unit” in the claims. The photometric prism 8, the photometric lens 9, the photometric element 10, and the photometric unit 13 correspond to the “photometric unit” in the claims, and the calculation unit 14 and the operation unit 16 correspond to the “selecting unit” in the claims. To do.

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. The area to be measured in each photometry mode corresponds to the “predetermined area of the object scene” in the claims.

In step S <b> 3, the calculation unit 14 calculates a representative luminance value BVexp based on the luminance value detected according to the photometric mode by the photometric unit 13. The representative luminance value BVexp is a value obtained as a value representative of all the photometric areas in consideration of each luminance value detected by the photometric unit 13.
That is, when the central partial photometry mode is set by the user, the calculation unit 14 calculates the representative 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 the representative 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 a representative 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 photometry mode is set by the user, the representative luminance value BVexp = BVcw is set, and when the spot photometry mode is set, the representative luminance value BVexp = BVsp is set, and the multi-division photometry mode is set. In this case, the representative luminance value BVexp = BVa.

Specific calculation methods for these representative luminance values (BVcw, BVsp, BVa) are the same as the methods disclosed in, for example, JP-A-9-281543 and JP-A-63-170628. Detailed description will be omitted.
In step S <b> 4, the calculation unit 14 calculates an average luminance value BVsht based on the 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 calculation unit 14 calculates an exposure control parameter based on the representative luminance value BVexp calculated in step S3 and the exposure correction value and the bracketing value set by the operation unit 16. The calculation unit 14 is provided with calculation formulas for calculating the shutter speed, the aperture value, and the sensitivity of the image sensor 12 based on the representative luminance value BVexp, the exposure correction value, and the bracketing value. 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 photometry unit control parameter indicates an amplifier gain when the photometry element 10 of the photometry unit 13 is SPD, and an amplifier gain and an accumulation time when it is a CCD, and is a photometric condition in the photometry unit 13. 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 the average luminance value BVsht based on the luminance value of the corrected reference area detected by the photometry unit 13, as in step S4. When the average luminance value BVsht 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 average luminance value in the corrected reference area until the release button is fully pressed (YES in step S6). The calculation of BVsht 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), photometry, calculation of the representative luminance value BVexp, and average luminance value until the release button is fully pressed (YES in step S6). The calculation of BVsht, 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.
When the digital gain process is performed, in step S13, the memory unit 19 records the image data corrected by the image correction unit 18, and ends the series of processes.

Hereinafter, digital gain processing, which is a feature of the present invention, will be described with reference to the flowchart of FIG.
In step S21, the calculation unit 14 first obtains an exposure error amount ExpErr.
FIG. 6 is a diagram illustrating the imaging element 12 of the imaging unit 17. Each square in FIG. 6 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 ^ (BVsht−BVexp + BVec + BVbkt) (Formula 2)
In Expression 2, 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. In Expression 2, 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." As described in Equation 2, by determining the target luminance output correction coefficient HT in consideration of the manual exposure correction value BVec and the bracketing value BVbkt, the user's intention can be reflected in correction described later.

Note that the target luminance output correction coefficient HT corresponds to the “target luminance value” in the claims, and, as is clear from Equation 2, the representative luminance value BVexp (corresponding to “the luminance of the first region” in the claims) and the average It is calculated based on the luminance value BVsht (corresponding to “luminance of the second region” in the claims).
Next, the calculation unit 14 obtains the target luminance output TgY during shooting using the following equation.
TgY = TgS × HT (Formula 3)
In Expression 3, the shooting target luminance output 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 portion of image data to be processed. TgS is a reference target luminance output that is set in advance so that a uniform gray (halftone) subject is imaged in advance, and image data obtained by this imaging becomes preferable gray (reproduced as halftone). It is. However, the reference target luminance output TgS is free from a control error of the aperture stop 2 and the shutter 11 by the control unit 15, and is a gray subject under the conditions of manual exposure correction value BVec = 0 and representative luminance value BVexp = average luminance value BVsht. And the image data obtained when the digital gain correction according to the present invention is not performed is determined to be a preferable gray. That is, the reference target luminance output TgS is determined so that the average photometric photographing result in a state where there is no control error and digital gain correction is not performed is gray.

And 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. The reference target luminance output TgS described above is equal to the average luminance output AveYref when there is no control error of the aperture stop 2 and the shutter 11 by the control unit 15.

Next, the calculating part 14 calculates | requires digital gain correction coefficient CT using following Formula in step S22.
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). The digital gain correction coefficient CT corresponds to the “correction value used when correcting the image” in the claims, and as is clear from the equations 4 and 6, the average luminance output AveYref (the “object field” in the claims) And a target luminance output TgY during shooting (corresponding to “target luminance value of predetermined region” in the claims).

And the calculating part 14 correct | amends the image data output from the imaging part 17 using following Formula in step S23.
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. When this image data is corrected based on an exposure error amount ExpErr smaller than 1, all the corrected image data Dr, Dg, and Db have values that are 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, for example, when the image to be corrected includes image data reaching the dynamic range and the exposure error amount ExpErr is smaller than 1, the correction contribution ratio AP = 0 may be set. 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.

Hereinafter, a method for setting the value of the correction contribution rate AP will be described. Note that the value of the correction contribution rate AP may be set by combining the methods described below. Thus, the optimum digital gain process can be performed by setting the correction contribution rate AP in accordance with the shooting situation.
When there is image data that has reached the dynamic range in the corrected reference area, the average luminance output AveYref is 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 a function of the image data that has reached the dynamic range in the correction reference area, as shown in the following equation.

AP = 1−β × countDY (Equation 8)
In Equation 8, countDY is the number of image data that has reached the dynamic range in the corrected reference area. Β is a positive decimal number obtained in advance through experiments or the like. However, when 1 <β × countDY, the correction contribution ratio AP = 0. By setting the correction contribution ratio AP using Equation 8, the image data that has reached the dynamic range (image data that has reached the saturation level) within the correction reference region (the portion corresponding to the predetermined region of the object scene) is obtained. The digital gain correction coefficient CT can be obtained so that the degree of correction decreases as the number increases.

In addition, when subjects with a large luminance difference are mixed in the same screen, the image data of a portion with a large luminance value often exceeds the dynamic range even when shooting is performed with the optimum exposure. Therefore, for example, the correction contribution rate AP may be a function of the difference between the maximum value and the minimum value of the image data in the correction reference area as shown in the following equation.
AP = 1−γ × difY (Equation 9)
In Expression 9, difY is a difference between the maximum value and the minimum value of the image data in the correction reference area. Further, γ is a positive decimal number obtained in advance through experiments or the like. However, when 1 <γ × difY, the correction contribution ratio AP = 0. By setting the correction contribution rate AP using Equation 9, the degree of correction increases as the difference between the maximum luminance value and the minimum luminance value in the correction reference area (the part corresponding to the predetermined area of the object scene) increases. The digital gain correction coefficient CT can be obtained so as to decrease.

  Further, the correction contribution ratio AP may be obtained based on the data detected by the photometry unit 13 in order to simplify the processing, reduce the load on the control unit 15 and the calculation unit 14 and reduce the processing time. In general, since the photometry unit 13 has a smaller number of data than the imaging unit 17, the load on the calculation unit 14 is small, and as a result, the processing time can be shortened. A specific method will be described below.

  For example, the correction contribution rate AP is a function of the representative luminance value BVexp when obtaining the exposure control parameter. For example, when shooting a night view, the image data of a light source such as a streetlight often far exceeds the dynamic range even when shooting at an optimal exposure. When shooting a night scene, the representative luminance value BVexp is generally small (dark). Therefore, a function that reduces the correction contribution rate AP when the representative luminance value BVexp becomes smaller may be used. By setting the correction contribution rate AP in this way, the digital gain correction coefficient is set such that the lower the representative luminance value BVexp (the luminance in the predetermined area out of the luminance detected by the photometry unit 13) is, the smaller the degree of correction is. CT can be determined.

  Further, for example, the correction contribution ratio AP is set to the brightness values BV (1) to BV (9), BV (13), BV (14), BV (17), BV (in the correction reference area detected by the photometry unit 13. 18), and a function of the difference between the maximum value and the minimum value of BV (21) and BV (22). When a subject with a large luminance difference is mixed in the same screen, the image data of a portion with a large luminance value often exceeds the dynamic range even if shooting is performed with an optimal exposure. Therefore, the maximum values of the luminance values BV (1) to BV (9), BV (13), BV (14), BV (17), BV (18), BV (21), and BV (22) in the correction reference area. When the difference between the minimum value and the minimum value increases, the correction contribution ratio AP may be reduced. That is, in the same manner as the correction contribution rate AP described using Expression 9 is a function of the difference between the maximum value and the minimum value of the image data in the correction reference region, the maximum luminance value in the correction reference region A function of the difference from the minimum value may be used. By setting the correction contribution rate AP in this way, the difference between the maximum value and the minimum value of the luminance values in the correction reference region (the maximum luminance value and the minimum luminance among the luminances of the plurality of regions detected by the photometry unit). The digital gain correction coefficient CT can be obtained so that the degree of correction decreases as the difference between the values increases.

  Further, 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 in the correction reference area detected by the photometry unit 13. (18) The maximum value of BV (21) and BV (22) may be used. When a high-luminance subject such as the sun is reflected, the image data of the high-luminance subject portion often far exceeds the dynamic range even when shooting is performed with the optimum exposure. Since the luminance value of the photometry area corresponding to such a high-luminance subject is very large, the luminance values BV (1) to BV (9), BV (13), BV (14), and BV (17) in the correction reference area. ), BV (18), BV (21), and BV (22) may be a function such that the correction contribution ratio AP decreases as the maximum value increases. By setting the correction contribution rate AP in this way, the degree of correction decreases as the maximum value of the luminance value in the correction reference region (the maximum luminance value of the luminance for each of the plurality of regions detected by the photometry unit) increases. Thus, the digital gain correction coefficient CT can be obtained.

  In addition, by selecting one of the shooting scenes prepared in advance in the electronic camera, such as a portrait or landscape, the electronic camera automatically selects the optimal exposure control parameter combination for that shooting scene. When the present invention is applied to an electronic camera having a so-called scene mode, the value of the correction contribution rate AP may be set according to the shooting scene selected by the user. That is, by setting the correction contribution rate AP according to the shooting scene, the digital gain correction coefficient CT is obtained based on the ratio (exposure error amount ExpErr) between the average luminance output AveYref and the shooting target luminance output TgY and the shooting scene. (See Equation 5).

For example, when the night view or the fireworks mode is selected, the correction contribution ratio AP = 0 may be set for the same reason as described above. One shooting scene described above may be selected by a user operation via the operation unit 16, or may be automatically selected by an electronic camera performing frequency analysis.
When shooting using a flash device, the representative brightness value BVexp and the average brightness value BVsht are acquired with the flash device turned off before shooting, and the flash device is emitting light at the time of shooting. The average luminance output AveYref is acquired. Therefore, an appropriate exposure error amount ExpErr may not be obtained. In consideration of such a case, the correction contribution ratio AP = 0 may be used when the flash device is used.

  As described above, according to the first embodiment, the luminance value (average luminance output AveYref) of the portion corresponding to the predetermined area of the object scene in the image generated by imaging the object scene and the predetermined area Based on the ratio to the target brightness value (shooting target brightness output TgY), a correction value (digital gain correction coefficient CT) used for correcting the image is calculated and corrected, and the image obtained by imaging is corrected. Of these, the correction value (digital gain correction coefficient CT) is such that the greater the number of image data that has reached the saturation level in the portion corresponding to the predetermined area of the object scene (in the correction reference area), the smaller the degree of correction. Is calculated. Therefore, there is no need to measure and store the amount of error in advance, so that an image with appropriate brightness can be easily obtained without increasing the memory capacity. In particular, in the image data of the image obtained by imaging, the correction value is calculated so that the degree of correction becomes smaller as the number of image data that has reached the saturation level is larger. Therefore, the average luminance output AveYref is the original value of the subject. It can be prevented that the value becomes smaller than the luminance. Therefore, it is possible to suppress the occurrence of false colors in the corrected image when, for example, whiteout occurs in part of the image due to overexposure.

  Further, according to the first embodiment, the correction value is calculated so that the degree of correction becomes smaller as the difference between the maximum luminance value and the minimum luminance value of the portion corresponding to the predetermined area of the object scene increases. Therefore, even if a subject with a large luminance difference is mixed on the same screen, even if an image exceeding the dynamic range is obtained as a result of shooting with the optimum exposure, the corrected image is false. The generation of color can be suppressed.

Further, according to the first embodiment, the correction value is calculated based on the ratio between the luminance value of the portion corresponding to the predetermined area of the object scene and the target luminance value of the predetermined area and the selected one shooting scene. To do. Therefore, it is possible to easily obtain an image with appropriate brightness according to the shooting scene.
Further, according to the first embodiment, the correction value is calculated so that the degree of correction becomes smaller as the luminance in the predetermined area is lower among the luminance detected by the photometry unit. Therefore, for example, when shooting a night scene, even if an image with some image data far exceeding the dynamic range is obtained as a result of shooting with an optimal exposure, the corrected image is also displayed. Generation of false colors can be suppressed.

  Further, according to the first embodiment, the correction value is calculated so that the degree of correction decreases as the difference between the maximum luminance value and the minimum luminance value among the luminances of the plurality of areas detected by the photometry unit increases. To do. Therefore, even if a subject with a large luminance difference is mixed on the same screen, even if an image exceeding the dynamic range is obtained as a result of shooting with the optimum exposure, the corrected image is false. The generation of color can be suppressed.

  Further, according to the first embodiment, the correction value is calculated so that the degree of correction becomes smaller as the maximum luminance value of each of the plurality of areas detected by the photometry unit increases. Therefore, when a high-brightness subject is captured, even when an image in which the image data of the high-brightness subject part far exceeds the dynamic range is obtained as a result of shooting with an optimal exposure, It is possible to suppress the occurrence of false colors in the corrected image.

Further, as described in the first embodiment, even an interchangeable lens camera can easily obtain an image with appropriate brightness without increasing the memory capacity.
Further, according to the first embodiment, the luminance related to the first area and the second area of the object scene is detected, and the luminance of the first area (representative luminance value BVexp) and the luminance of the second area (average luminance value BVsht) are detected. ) To calculate a target luminance value (target luminance output correction coefficient HT). Therefore, the correction value is calculated based on the target luminance value suitable for the image and the correction is performed, so that an image with appropriate brightness can be obtained.

Further, according to the first embodiment, in the multi-division metering mode, the target luminance value is calculated based on the representative value based on the luminance detected for each of the plurality of areas. An image can be obtained.
In the first embodiment, an example in which the fixed reference target luminance output TgS is used has been described. However, for example, the reference target luminance output TgS may be appropriately changed according to the white balance mode. In this way, more appropriate correction can be performed by appropriately changing the reference target luminance output 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 the user performs exposure setting. Can be applied. In the case of the manual exposure mode, the representative 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 imaging selected by the user. What is necessary is just to calculate from the sensitivity of the element 12. By calculating the representative 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, the representative brightness value BVexp cannot be calculated because the shutter speed is not known in advance. 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, and the image correction unit 20 corrects the image data according to the procedure described with reference to FIGS. 4 and 5 and displays it 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 includes the image data (processing target image) obtained by the imaging, and the photometric area in the object scene as the imaging conditions when the image is captured, such as FIGS. 4 and 5 of the first embodiment. An imaging condition capable of performing correction similar to the correction described in the above 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 in which correction similar to the flowcharts of FIGS. 4 and 5 of the first embodiment is performed has been described. However, only a part of each step of the flowcharts of FIGS. You may make it do.

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 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 functional block diagram of a computer of a 2nd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens 2 Aperture stop 3 Quick return mirror 4 Diffusion screen 5 Condenser lens 6 Penta prism 7 Eyepiece lens 8 Photometric prism 9 Photometric lens 10 Photometric element 11 Shutter 12 Imaging element 13 Photometric part 14 Calculation part 15 Control part 16 Operation part 17 Imaging unit 18, 20 Image correction unit 19 Memory unit 21 Display unit 22 Reading unit 100, 300 Electronic camera 101 Camera body 102 Shooting lens 200 Computer

Claims (18)

An imaging unit that images an object scene and generates an image;
Based on the ratio between the luminance value of the portion corresponding to the predetermined area of the object scene in the captured image and the target luminance value of the predetermined area, a correction value used when correcting the image is calculated. An arithmetic unit to perform,
A correction unit that corrects the image based on the correction value calculated by the calculation unit,
In the portion corresponding to the predetermined area of the object scene in the image, the calculation unit performs the correction so that the greater the number of image data that has reached the saturation level, the smaller the degree of correction by the correction unit. An electronic camera characterized by calculating a value. An imaging unit that images an object scene and generates an image;
Based on the ratio between the luminance value of the portion corresponding to the predetermined area of the object scene in the captured image and the target luminance value of the predetermined area, a correction value used when correcting the image is calculated. An arithmetic unit to perform,
A correction unit that corrects the image based on the correction value calculated by the calculation unit,
The calculation unit calculates the correction value such that the degree of correction becomes smaller as the difference between the maximum luminance value and the minimum luminance value of the portion corresponding to the predetermined area of the scene in the image increases. An electronic camera characterized by that. A selection unit for selecting one shooting scene from a plurality of predetermined shooting scenes;
An imaging unit that captures an image of the scene in accordance with a shooting condition determined according to the one shooting scene selected by the selection unit;
Based on the ratio of the luminance value of the portion corresponding to the predetermined area of the object scene to the target luminance value of the predetermined area in the captured image and the one shooting scene selected by the selection unit. A calculation unit for calculating a correction value used when correcting the image;
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 any one of claims 1 to 3,
A photometric unit for detecting the luminance related to the first region and the second region of the object scene;
The said calculating part calculates the said target luminance value based on the brightness | luminance of said 1st area | region, and the brightness | luminance of said 2nd area | region. The electronic camera characterized by the above-mentioned. An imaging unit that images an object scene and generates an image;
A photometric unit for detecting the brightness of the object field;
Based on the ratio between the luminance value of the portion corresponding to the predetermined area of the object scene in the captured image and the target luminance value of the predetermined area, a correction value used when correcting the image is calculated. An arithmetic unit to perform,
A correction unit that corrects the image based on the correction value calculated by the calculation unit,
The electronic camera is characterized in that the calculation unit calculates the correction value such that the lower the luminance in the predetermined region out of the luminance detected by the photometry unit, the smaller the degree of correction. An imaging unit that images an object scene and generates an image;
A photometric unit that divides a predetermined area of the object scene into a plurality of areas and performs photometry, and detects luminance;
Based on the ratio between the luminance value of the portion corresponding to the predetermined area of the object scene in the captured image and the target luminance value of the predetermined area, a correction value used when correcting the image is calculated. An arithmetic unit to perform,
A correction unit that corrects the image based on the correction value calculated by the calculation unit;
The calculation unit calculates the correction value so that the degree of correction becomes smaller as the difference between the maximum luminance value and the minimum luminance value among the luminances of the plurality of areas detected by the photometry unit increases. An electronic camera characterized by An imaging unit that images an object scene and generates an image;
A photometric unit that divides a predetermined area of the object scene into a plurality of areas and performs photometry;
Based on the ratio between the luminance value of the portion corresponding to the predetermined area of the object scene in the captured image and the target luminance value of the predetermined area, a correction value used when correcting the image is calculated. An arithmetic unit to perform,
A correction unit that corrects the image based on the correction value calculated by the calculation unit,
The electronic camera is characterized in that the calculation unit calculates the correction value so that the degree of correction becomes smaller as the maximum luminance value of the plurality of areas detected by the photometry unit increases. The electronic camera according to any one of claims 5 to 7,
The photometry unit detects the luminance related to the first region and the second region of the object scene,
The said calculating part calculates the said target luminance value based on the brightness | luminance of said 1st area | region, and the brightness | luminance of said 2nd area | region. The electronic camera characterized by the above-mentioned. The electronic camera according to claim 4 or 8,
The light metering unit divides the first region of the object scene into a plurality of regions and measures the light to detect the luminance for each of the plurality of regions,
The electronic camera characterized in that the calculation unit calculates the target luminance value based on a representative value based on the luminance for each of the plurality of regions detected by the photometry unit and the luminance of the second region. An acquisition procedure for acquiring an image to be processed;
A calculation procedure for calculating a correction value to be used when correcting the image based on a ratio between a luminance value of a portion corresponding to a predetermined area in the image to be processed and a target luminance value of the predetermined area;
An image processing program for causing a computer to execute a correction procedure for correcting the image based on the correction value calculated in the calculation procedure,
In the calculation procedure, the correction value is calculated so that the degree of correction decreases as the number of image data that reaches a saturation level increases in a portion of the image corresponding to the predetermined area of the object scene. An image processing program characterized by that. An acquisition procedure for acquiring an image to be processed;
A calculation procedure for calculating a correction value to be used when correcting the image based on a ratio between a luminance value of a portion corresponding to a predetermined area in the image to be processed and a target luminance value of the predetermined area;
An image processing program for causing a computer to execute a correction procedure for correcting the image based on the correction value calculated in the calculation procedure,
In the calculation procedure, the correction value is calculated so that the degree of correction decreases as the difference between the maximum luminance value and the minimum luminance value of a portion of the image corresponding to the predetermined area of the object scene increases. An image processing program characterized by that. A selection unit that selects one shooting scene from a plurality of predetermined shooting scenes, and an image of the scene according to shooting conditions determined according to the one shooting scene selected by the selection unit An image processing program for causing a computer to execute image processing on an image generated by an imaging device including an imaging unit that generates an image,
An acquisition procedure for acquiring the one shooting scene selected by the selection unit and the photometric area in the object scene and the luminance relating to the photometric area as an imaging condition when the image is captured together with the image to be processed;
Of the image to be processed, the image is corrected based on a ratio between a luminance value of a portion corresponding to a predetermined area and a target luminance value of the predetermined area and the one shooting scene selected by the selection unit. A calculation procedure for calculating a correction value to be used when
An image processing program for causing a computer to execute a correction procedure for correcting the image based on the correction value calculated in the calculation procedure. The image processing program according to any one of claims 10 to 12,
In the acquisition procedure, along with the image to be processed, the luminance relating to the photometric area and the photometric area in the object scene is acquired as an imaging condition when the image is captured,
In the calculation procedure, a target luminance value is calculated based on the luminance of the first region and the luminance of the second region in the photometric region. An acquisition procedure for acquiring the luminance relating to the photometric area in the object scene and the photometric area as an imaging condition when the image is captured together with the image to be processed;
A calculation procedure for calculating a correction value to be used when correcting the image based on a ratio between a luminance value of a portion corresponding to a predetermined area in the image to be processed and a target luminance value of the predetermined area;
An image processing program for causing a computer to execute a correction procedure for correcting the image based on the correction value calculated in the calculation procedure,
In the calculation procedure, the correction value is calculated so that the degree of correction becomes smaller as the luminance in the predetermined area is lower in the luminance acquired in the acquisition procedure. An acquisition procedure for acquiring a plurality of photometric areas obtained by dividing the object scene and luminance for each of the plurality of areas as an imaging condition when the image is captured together with an image to be processed;
A calculation procedure for calculating a correction value to be used when correcting the image based on a ratio between a luminance value of a portion corresponding to a predetermined area in the image to be processed and a target luminance value of the predetermined area;
An image processing program for causing a computer to execute a correction procedure for correcting the image based on the correction value calculated in the calculation procedure,
In the calculation procedure, the correction value is calculated so that the degree of correction decreases as the difference between the maximum luminance value and the minimum luminance value among the luminances of the plurality of areas acquired in the acquisition procedure increases. An image processing program characterized by the above. An acquisition procedure for acquiring a plurality of photometric areas obtained by dividing the object scene and luminance for each of the plurality of areas as an imaging condition when the image is captured together with an image to be processed;
A calculation procedure for calculating a correction value to be used when correcting the image based on a ratio between a luminance value of a portion corresponding to a predetermined area in the image to be processed and a target luminance value of the predetermined area;
An image processing program for causing a computer to execute a correction procedure for correcting the image based on the correction value calculated in the calculation procedure,
In the calculation procedure, the correction value is calculated so that the degree of correction decreases as the maximum luminance value of the plurality of areas acquired in the acquisition procedure increases. The image processing program according to any one of claims 14 to 16,
In the calculation procedure, a target brightness value is calculated based on the brightness of the first area and the brightness of the second area in the photometric area. The image processing program according to claim 13 or 17,
In the acquisition procedure, the luminance for each of a plurality of areas obtained by dividing and metering the first area into a plurality of areas is acquired,
In the calculation procedure, the target brightness value is calculated based on a representative value based on brightness for each of the plurality of areas and brightness of the second area.

Images