JP5515795B2 - Imaging apparatus and imaging method - Google Patents

Description

  The present invention relates to an imaging apparatus such as a digital still camera and an imaging method.

  Conventionally, by combining multiple captured images obtained by shooting the same subject with dark and bright areas under different exposure conditions, one composition where the dark areas are not crushed black and the bright areas are not flying white A high dynamic range (hereinafter, referred to as “HDR”) imaging technique capable of generating an image is known (see, for example, Patent Document 1).

JP 2003-319240 A

  By the way, in the conventional HDR imaging technique, for example, when two captured images with different exposure conditions are obtained, the exposure on the high exposure side in which the number of exposure stages is different from the normal exposure condition by a certain number of stages on the high exposure side and the low exposure side. One synthesized image is generated by synthesizing two captured images taken under the condition and the exposure condition on the low exposure side. That is, the exposure conditions on the high exposure side and the low exposure side are uniquely determined regardless of the actual contrast ratio between the dark part and the bright part in the subject. For this reason, it has been difficult to say that a composite image obtained by such a conventional HDR photography technique was photographed under an optimum exposure condition corresponding to the contrast ratio between the dark part and the bright part of the subject.

  The present invention has been made in view of such circumstances, and an object of the present invention is to shoot an object having a dark part and a bright part under a high dynamic range under an optimum exposure condition corresponding to the contrast ratio between the dark part and the bright part. It is an object to provide an imaging apparatus and an imaging method capable of performing the above.

In order to achieve the above object, an imaging apparatus of the present invention includes a luminance value detection unit that measures a subject image formed on a light receiving surface of an imaging element for each of a plurality of divided areas and detects a luminance value for each area; The first exposure condition is determined based on the first luminance value, with the maximum luminance value or the high luminance value according to the maximum luminance value among the luminance values detected by the luminance value detecting means as the first luminance value. And the exposure condition determining means for determining the second exposure condition based on the second brightness value using the minimum brightness value of the brightness values or a low brightness value corresponding to the minimum brightness value as the second brightness value. And composite image generating means for generating a composite image by combining the captured images respectively captured according to the first exposure condition and the second exposure condition determined by the exposure condition determining means , the exposure The condition determining means is the first luminance value When the step number difference between the exposure step number corresponding to the exposure step calculated based on the exposure level calculated based on the second luminance value and the exposure step number corresponding to the exposure condition calculated based on the second luminance value exceeds a preset step number threshold value, the step number difference becomes the step number threshold value. Summary of the invention is to adjust the number of exposure steps corresponding to the exposure condition calculated based on the second luminance value, and to determine the exposure condition corresponding to the number of exposure steps after the adjustment as the second exposure condition, as described below. And

  In the imaging apparatus according to the aspect of the invention, the exposure condition determination unit may have a numerical difference between an average value of the luminance values among the luminance values detected by the luminance value detection unit exceeds a preset abnormality threshold value. When there is a luminance value, the first exposure condition and the second exposure condition are determined based on the first luminance value and the second luminance value in the remaining luminance values excluding the luminance value exceeding the abnormal value. This is the gist.

In the imaging apparatus of the present invention, the first luminance value is pre Symbol maximum luminance value, and summarized in that the second luminance value is pre SL minimum luminance value.

In addition, the imaging method of the present invention includes a luminance value detection step for measuring a subject image formed on a light receiving surface of an imaging element for each of a plurality of divided regions and detecting a luminance value for each region, and the luminance value detection step. The first exposure condition is determined based on the first luminance value, with the maximum luminance value of the detected luminance values or the high luminance value according to the maximum luminance value as the first luminance value, An exposure condition determination step for determining a second exposure condition based on the second brightness value, with the minimum brightness value of the brightness values or a low brightness value corresponding to the minimum brightness value as the second brightness value; and the exposure condition A composite image generation step of generating a single composite image by combining the captured images captured according to the first exposure condition and the second exposure condition determined in the determination step, and in the exposure condition determination step, The first luminance value When the step number difference between the exposure step number corresponding to the exposure step calculated based on the exposure level calculated based on the second luminance value and the exposure step number corresponding to the exposure condition calculated based on the second luminance value exceeds a preset step number threshold value, the step number difference becomes the step number threshold value. Summary of the invention is to adjust the number of exposure steps corresponding to the exposure condition calculated based on the second luminance value, and to determine the exposure condition corresponding to the number of exposure steps after the adjustment as the second exposure condition, as described below. And

  According to the present invention, a subject having a dark part and a bright part can be photographed with a high dynamic range under an optimum exposure condition corresponding to the contrast ratio between the dark part and the bright part.

1 is a block diagram showing a schematic configuration of a digital still camera according to an embodiment. The screen figure of the to-be-photographed image divided | segmented into the several area | region for every area | region photometry. The flowchart of a HDR imaging | photography process routine.

  FIG. 1 shows an embodiment in which the present invention is embodied in a digital still camera (hereinafter referred to as “camera”) as an imaging apparatus and an imaging method in the case of photographing a subject with high dynamic range (HDR) using the camera. Description will be made with reference to FIG.

  As shown in FIG. 1, the camera 11 includes a lens unit 12 composed of a plurality of lenses such as a zoom lens (only one lens is shown in FIG. 1 for simplification of the drawing), and object light that has passed through the lens unit 12. A diaphragm 13 that adjusts the amount of light and an imaging element 14 that forms an image of subject light that has passed through the diaphragm 13 on an incident-side light-receiving surface 14a that serves as an imaging surface. An AFE (Analog Front End) 15 and an image processing circuit 16 are connected in series on the output side of the image sensor 14, and an MPU (Micro Processing Unit) 17 is connected to the image processing circuit 16 by a data bus 18. Connected through.

  In addition, a nonvolatile memory 19 that stores a control program for the camera 11, a RAM 20 that functions as a buffer memory, a liquid crystal display monitor 21 that functions as a display unit, and a memory card 22 that is a recording medium can be inserted into and removed from the MPU 17. A card I / F (Inter-Face) 23 is connected via a data bus 18. Further, on the camera body, an operation member 24 such as a mode switching button or a release button operated by the user of the camera 11 sends each operation signal (mode switching signal, half-press operation signal, etc.) to the MPU 17. Provided for data communication.

  The imaging element 14 is composed of a complementary metal oxide semiconductor (CMOS) image sensor or a charge coupled device (CCD) image sensor, has an electronic shutter function, and has a large number of light receiving elements (not shown) on its light receiving surface 14a. Dimensionally arranged. The image sensor 14 accumulates signal charges corresponding to the subject image formed on the light receiving surface 14a, and outputs the accumulated signal charges to the AFE 15 as analog signals called pixel signals that are the source of image data.

  The AFE 15 samples a pixel signal of an analog signal input from the image sensor 14 at a predetermined timing (correlated double sampling), and amplifies the signal to a predetermined signal level based on ISO sensitivity, for example. And an A / D converter (not shown) for converting the amplified pixel signal into a digital signal. The AFE 15 outputs image data generated by digitizing the pixel signal of the analog signal by the A / D conversion unit to the image processing circuit 16.

  The image processing circuit 16 performs various types of image processing (for example, image generation processing for combining captured images in HDR imaging) on the image data input from the AFE 15 based on a control signal from the MPU 17. Then, the image processing circuit 16 temporarily stores the image data subjected to such image processing in the RAM 20 and displays it on the monitor 21 as a through image. When the release button is fully pressed, the image corresponding to the image data at that time is displayed on the monitor 21 as a confirmation image, and on the other hand, predetermined image processing such as format processing for JPEG compression is performed. After that, it is recorded as an image file in the memory card 22.

  The MPU 17 comprehensively controls various processing operations (for example, HDR imaging processing) in the camera 11 based on a control program stored in the nonvolatile memory 19. The data bus 18 functions as a transmission path for various data accompanying the control of the MPU 17. The mode switching button on the operation member 24 is a button that is operated when switching the operation mode of the camera 11. For example, the mode switching button is operated when the shooting mode is switched between the normal shooting mode and the HDR shooting mode. Similarly, the release button is pressed down when the subject is photographed when the operation mode of the camera 11 is the photographing mode.

  In the camera 11, AF (Auto Focus) processing for focusing on the subject and AE (Auto Exposure) processing for exposure adjustment when the release button of the operation member 24 is half-pressed in the normal shooting mode. After that, the composite image generation process is executed when the release button is fully pressed. On the other hand, in this camera 11, when the release button of the operation member 24 is half-pressed in the HDR shooting mode, the AE processing and synthesis for HDR shooting different from the AE processing and the combined image generation processing in the normal shooting mode are performed. Image generation processing is executed.

  That is, in the HDR shooting mode, the first exposure condition on the high exposure side and the first exposure condition on the low exposure side necessary for HDR shooting of a subject having a dark part and a bright part like the subject in the photograph 25 shown in FIG. 2 AE processing for determining exposure conditions is executed. Incidentally, the photograph 25 in FIG. 2 is a subject in which the sun 26 is located on the upper left side of the mountain 27 and the surface of the lake 28 at the foot of the mountain is shaded by the trees 29 on the lakeside and becomes dark. It is. Therefore, in the subject image of the landscape photograph 25, the area A and the area E in which the bright sun 26 is located in the area are bright areas, while the area P and the sun 26 in which the lake 28 with the shaded surface is located in the area. A region L where the standing tree 29 is located in the region is a dark part.

  When the light from the subject of the photograph 25 shown in FIG. 2 is measured for each of the areas A to P and the luminance value for each of the areas A to P is detected, most of the sun 26 is located in the area A in the upper left corner. Therefore, the luminance value of the area A in the upper left corner is the maximum luminance value. Since a part of the sun 26 is located in the region E immediately below the region A, the luminance value of the region E becomes a high luminance value according to the maximum luminance value. Therefore, in the subject in the photograph 25, a group of high luminance values including the maximum luminance value is constituted by the luminance value of the region A and the luminance value of the region E.

  On the other hand, since the lake 28 with a dark lake surface is located in the area P in the lower right corner, the luminance value of the area P in the lower right corner becomes the minimum luminance value. In the region L immediately above the region P, the standing tree 29 on the lakeside is located with the light from the sun 26 in the back (specifically, received from the rear left side). Is a low-brightness luminance value according to the minimum luminance value. Accordingly, in the subject in the photograph 25, a group of low luminance values including the minimum luminance value is constituted by the luminance value of the region P and the luminance value of the region L.

  In the case of the present embodiment, when the first exposure condition and the second exposure condition are determined based on the luminance value for each of the areas A to P in the subject image having the dark part and the bright part, the dark part (areas P and L) is determined. ) And a bright part (areas A and E) are continuously shot under the first exposure condition and the second exposure condition. Incidentally, in the case of the present embodiment, the AE process for HDR imaging is executed by adjusting the electronic shutter speed of the image sensor 14. Specifically, as the electronic shutter speed for continuous shooting, the first shutter speed on the high speed side that is the first exposure condition and the second shutter speed on the low speed side that is the second exposure condition are set. ing.

  After that, when the release button is fully pressed, the same subject having the dark part (areas P and L) and the bright part (areas A and E) is set to the first shutter speed (first exposure condition) and the second shutter. A composite image is generated by combining two captured images obtained by continuous shooting at a speed (second exposure condition).

  Next, an outline of the HDR imaging processing routine executed by the MPU 17 when HDR imaging of a subject having a dark part and a bright part using the camera 11 will be described below with reference to the flowchart of FIG.

  When the shooting mode is switched from the normal shooting mode to the HDR shooting mode by operating the mode switching button of the operation member 24 when the operation mode of the camera 11 is the shooting mode, the MPU 17 in FIG. The HDR imaging processing routine shown in the flowchart is started.

  First, in step S11, the MPU 17 determines whether or not the release button of the operation member 24 is half-pressed. When the determination result in step S11 is negative (step S11 = NO), the MPU 17 periodically repeats the determination in step S11. And if the determination result of this step S11 becomes affirmation determination (step S11 = YES), MPU17 will transfer the process to the following step S12.

  In the next step S12, the MPU 17 detects the luminance value for each of the areas A to P in the subject image displayed as a through image on the monitor 21 at that time. Specifically, the luminance signal Y and the color difference signals Cr and Cb are separated from the R, G, and B image data obtained by the image sensor 14, and the luminance signal Y is integrated for each of the regions A to P. Thus, the luminance value for each of the areas A to P is detected. In this respect, the MPU 17 functions as a luminance value detecting unit that executes a luminance value detecting step. When the luminance values in all the areas A to P are detected, the MPU 17 temporarily stores the detected luminance values in the RAM 20 in association with the areas A to P, and then proceeds to the next step S13. To do.

  In the next step S13, the MPU 17 determines whether or not there is an abnormal value in each luminance value for each of the areas A to P detected in the previous step S12. Specifically, an average value of all the detected luminance values is calculated, and it is determined whether there is a luminance value (abnormal value) in which a numerical difference from the average value exceeds a preset abnormality threshold value. And when the determination result of step S13 is affirmation determination (step S13 = YES), MPU17 transfers the process to the following step S14.

  Then, in the next step S14, the MPU 17 excludes the luminance values determined as abnormal values in step S13 from the luminance values for each of the areas A to P detected in the previous step S12, and leaves the remaining luminance values. A first luminance value and a second luminance value, which are luminance values for determining the first exposure condition and the second exposure condition, are selected. In the case of the present embodiment, one high luminance value having the maximum luminance is selected as the first luminance value among the remaining luminance values after the abnormal value is excluded, and the luminance among the remaining luminance values. Is selected as the second luminance value. Then, after temporarily storing the first luminance value and the second luminance value in the RAM 20, the MPU 17 proceeds to the next step S15. On the other hand, when the determination result of step S13 is negative (step S13 = NO), the MPU 17 directly shifts the process to step S15 without going through step S14.

  In the next step S15, the MPU 17 determines the first exposure step number and the second luminance value (for example, the region) corresponding to the first exposure condition calculated based on the first luminance value (for example, the maximum luminance value of the region A). It is determined whether or not the difference in the number of steps from the second number of exposure steps corresponding to the second exposure condition calculated based on the minimum brightness value of P exceeds a preset step number threshold (for example, five steps). And when the determination result of this step S15 is affirmation determination (step S15 = YES), MPU17 transfers the process to the following step S16.

  Then, in the next step S16, the MPU 17 determines at least one of the first exposure step number and the second exposure step number so that the step number difference between the first exposure step number and the second exposure step number is not more than the step number threshold value (5 steps). Adjust the number of exposure steps. The reason for adjusting the difference in the number of steps between the first exposure step number and the second exposure step number to be equal to or less than the step number threshold value (five steps) is as follows. This is because the combined image obtained by combining the two captured images captured under the exposure condition has no sense of incongruity.

  Incidentally, in the case of the present embodiment, the first exposure level corresponding to the first exposure condition calculated based on the first luminance value remains unchanged, and the second exposure condition calculated based on the second luminance value corresponds to the second exposure condition. 2 The number of exposure steps is adjusted (that is, the number of steps is made closer to the first exposure step number). Then, after temporarily storing each exposure step number in the RAM 20 after the step number difference is adjusted to be equal to or less than the step number threshold value (five steps), the MPU 17 proceeds to the next step S17. On the other hand, if the determination result of the previous step S15 is negative (step S15 = NO), the MPU 17 proceeds directly to step S17 without going through step S16.

  In the next step S17, the MPU 17 sets the first shutter speed and the second shutter speed as the first exposure condition based on the first exposure step number and the second exposure step number in which the step number difference is equal to or less than the step number threshold value (5 steps). The second shutter speed as an exposure condition is determined as the electronic shutter speed in the image sensor 14 during continuous shooting. In this respect, the MPU 17 functions as an exposure condition determination unit that executes an exposure condition determination step. Then, when the process of step S17 ends, the MPU 17 proceeds to the next step S18.

  In the next step S18, the MPU 17 determines whether or not the release button of the operation member 24 has been fully pressed. When the determination result in step S18 is negative (step S18 = NO), the MPU 17 periodically repeats the determination in step S18. And if the determination result of step S18 becomes affirmation determination (step S18 = YES), MPU17 will transfer the process to the following step S19.

  In the next step S19, the MPU 17 uses the image processing circuit 16 to obtain image data of two captured images obtained by continuously shooting the subject at the first shutter speed and the second shutter speed by the electronic shutter function of the image sensor 14. One synthesized image is generated by synthesizing. In this respect, the MPU 17 and the image processing circuit 16 function as a composite image generation unit that executes a composite image generation step. Then, after the composite image generated by such image processing is displayed on the monitor 21 as a confirmation image, the image data of the image is filed and stored in the memory card 22, and the MPU 17 performs the above HDR imaging processing. End the routine.

Next, the operation of the camera 11 according to the present embodiment configured as described above will be described below, particularly focusing on an imaging method in the case of subjecting a subject having a dark part and a bright part to HDR imaging.
As a premise of the description, the photograph taken by the camera 11 in this case is the landscape photograph 25 shown in FIG. 2, and as described above, the subject image in the photograph 25 has a dark part and a bright part. Shall. And about the brightness | luminance value for every area | region AP in the case where the to-be-photographed image is divided | segmented into 16 area | region AP, the brightness | luminance value of the area | region A of the upper left corner where most of the sun 26 is located in an area | region is maximum brightness | luminance. On the other hand, it is assumed that the luminance value of the area P in the lower right corner where the lake 28 with a dark lake surface is located in the area is the minimum luminance value. Furthermore, it is assumed that the shooting mode is switched from the normal shooting mode to the HDR shooting mode by operating the mode switching button on the operation member 24.

  Under the above premise, when the lens unit 12 of the camera 11 is directed toward the mountain 27 as a subject, the sun 26 rises above the left side of the ridgeline of the mountain 27 where the lake 28 and the standing tree 29 are located at the foot of the mountain. The landscape image in the state is displayed on the monitor 21 as a through image. In this state, when the user of the camera 11 presses the release button halfway, the AF process is automatically executed, and the image sensor 14 having an electronic shutter function as the AE process for HDR shooting is used. The shutter speed during shooting is determined.

  That is, the first shutter speed on the high speed side (first exposure condition on the high exposure side) is determined based on the maximum luminance value that is the luminance value of the area A among the luminance values of the areas A to P in the subject image. Further, the second shutter speed on the low speed side (second exposure condition on the low exposure side) is determined based on the minimum luminance value that is the luminance value of the area P among the luminance values of the areas A to P in the subject image.

  In this case, if the difference in the number of steps between the number of exposure steps at the first shutter speed and the number of exposure steps at the second shutter speed exceeds the step number threshold (five steps), the difference in the number of steps is less than the step number threshold. The number of exposure steps at the two shutter speeds is brought closer to the number of exposure steps at the first shutter speed. Then, each shutter speed corresponding to the exposure stage number after such adjustment of the stage number difference is determined as the first shutter speed and the second shutter speed for continuous shooting.

  In addition, regarding the luminance value of each of the areas A to P, which is the basis for calculating the shutter speed (exposure condition), when a luminance value with a numerical difference from the average luminance value of all areas exceeding the abnormal threshold is detected, the luminance value of that area Are excluded as abnormal values that are inappropriate for the basis of calculation of the shutter speed used for HDR imaging. Then, the first shutter speed and the second shutter speed are determined based on the remaining luminance values excluding such abnormal values.

  Then, after the first shutter speed and the second shutter speed are determined in this way, when the release button of the camera 11 is fully pressed, the subject image is continuously shot at the first shutter speed and the second shutter speed. . At that time, since the first shutter speed is a shutter speed that is an exposure condition suitable for the luminance value (maximum luminance value) of the area A that is a bright portion in the subject image, the first shutter speed is the first shutter speed. There is almost no occurrence of overexposure in one captured image. Similarly, since the second shutter speed is a shutter speed that is an exposure condition suitable for the luminance value (minimum luminance value) of the dark area P in the subject image, the second shutter speed photographed at the second shutter speed is used. There is almost no blackening in the captured image.

  Then, one composite image obtained by combining the first captured image and the second captured image obtained by such continuous shooting is generated in the image processing circuit 16 based on the control of the MPU 17. For example, the left half (areas A, B, E, F, I, J, M, and N) of the first captured image captured at the first shutter speed and the second captured image captured at the second shutter speed. The right half (regions C, D, G, H, K, L, O, P) is synthesized. Then, a single composite image is generated in which the dark portion is not blacked out and the bright portion is not overexposed, and the composite image is stored and saved in the memory card 22.

According to the present embodiment as described above, the following effects can be obtained.
(1) After detecting the luminance value for each of the plurality of divided areas A to P in the image of the subject having the dark part (area P) and the bright part (area A), the high-exposure second level is determined based on the luminance value of the bright part The first exposure condition is determined, and the second exposure condition for low exposure is determined based on the luminance value of the dark part. That is, the first shutter speed on the high speed side and the second shutter speed on the low speed side are determined as the exposure conditions for HDR shooting based on the actual brightness values (the first brightness value and the second brightness value) of the bright part and the dark part. Therefore, it is possible to perform HDR photography of an object having a dark part and a bright part under an optimum exposure condition corresponding to the contrast ratio between the dark part and the bright part.

  (2) When determining the first shutter speed (first exposure condition) and the second shutter speed (second exposure condition), the first exposure step number corresponding to the first shutter speed and the second shutter speed corresponding to the second shutter speed. When the difference in the number of steps from the two exposure steps exceeds the step number threshold (five steps), the second exposure step number is made closer to the first exposure step number so that the difference in the step number is equal to or less than the step number threshold. Then, two captured images obtained by continuously shooting the same subject having a dark portion and a bright portion under each exposure condition corresponding to each exposure step number after adjusting the step number difference are combined into one image. Since the composite image is generated, it is possible to suppress the possibility that the resulting composite image will be uncomfortable.

  (3) In particular, when adjusting the step number difference, the second exposure step number corresponding to the second exposure condition on the low exposure side is set as the adjustment target, so that the first exposure step number corresponding to the first exposure condition on the high exposure side is adjusted. Is kept as it is, so that the possibility of overexposure can be avoided.

  (4) The maximum luminance value, which is the luminance value of the brightest region A, is used as the first luminance value that is the basis for calculating the first exposure condition on the high exposure side, and is the basis for calculating the second exposure condition on the low exposure side. The minimum luminance value that is the luminance value of the darkest region P is used as the second luminance value. Therefore, it is possible to easily determine the exposure condition according to the light / dark ratio.

  (5) In the case where the luminance value for each of the areas A to P is detected, if there is an abnormal luminance value greatly deviating from the average luminance value, such abnormal luminance value is excluded, and the remaining luminance values The first and second luminance values that are the basis for calculating the first and second exposure conditions are selected. Therefore, the possibility of setting abnormal exposure conditions can be suppressed.

  (6) In the present embodiment, the number of exposure steps is set by the shutter speed among the shutter speed, aperture value, and ISO sensitivity, which are the three elements when determining the exposure value. Therefore, in contrast to the case where the exposure condition is set based on the aperture value or ISO sensitivity, the exposure condition can be easily set while suppressing the possibility that the depth of field changes or coloration occurs.

The above embodiment may be changed to another embodiment as described below.
In each of the above-described embodiments, the first luminance value and the second luminance value that are the basic values when determining the first exposure condition and the second exposure condition are high luminance values other than the maximum luminance value and the minimum luminance value, and A low luminance value may be used. For example, the luminance value of the second brightest region E (high luminance value) in the bright portion is used as the first luminance value, and the luminance value of the second darkest region L in the dark portion is used as the second luminance value. (Low luminance value) may be used. In short, one luminance value in a group of high luminance values including the maximum luminance value is set as the first luminance value, and one luminance value in the group of low luminance values including the minimum luminance value is set as the second luminance value. The first exposure condition on the high exposure side and the second exposure condition on the low exposure side may be determined.

In the above embodiment, the step of determining whether there is an abnormal brightness value among the brightness values detected for each of the regions A to P by comparison with the abnormal threshold value may be omitted.
In the above embodiment, the stage number threshold may be set to an arbitrary number of stages other than 5 (for example, 3, 4, 6, etc.).

  In the above embodiment, the second exposure step number is adjusted when the step number difference between the first exposure step number corresponding to the first exposure condition and the second exposure step number corresponding to the second exposure condition is within the step number threshold. Only the first exposure step number may be adjusted, or both the first exposure step number and the second exposure step number may be adjusted. That is, if the step number difference is within the step number threshold, at least one of the first exposure step number and the second exposure step number can be adjusted.

  In the above embodiment, when determining the exposure condition, the exposure condition may be determined based on the aperture value of the aperture 13 and the ISO sensitivity in addition to the shutter speed. That is, the exposure condition can be set by at least one of the shutter speed, aperture value, and ISO sensitivity.

  In the above embodiment, the present invention is embodied in a digital still camera which is a kind of imaging apparatus, but may be embodied in other imaging apparatuses such as a digital video camera or a mobile phone with a camera function and an imaging method using them. Good.

  DESCRIPTION OF SYMBOLS 11 ... Camera (imaging apparatus), 14 ... Imaging device (luminance value detection means), 14a ... Light-receiving surface, 16 ... Image processing circuit (composite image generation means), 17 ... MPU (exposure condition determination means, composite image generation means) , AP ... regions.

Claims (4)

A luminance value detecting means for measuring a subject image formed on a light receiving surface of an image sensor for each of a plurality of divided areas and detecting a luminance value for each area;
The first exposure condition is determined based on the first luminance value, with the maximum luminance value or the high luminance value according to the maximum luminance value among the luminance values detected by the luminance value detecting means as the first luminance value. And the exposure condition determining means for determining the second exposure condition based on the second brightness value using the minimum brightness value of the brightness values or a low brightness value corresponding to the minimum brightness value as the second brightness value. When,
Combined image generation means for generating a combined image by combining the captured images respectively captured according to the first exposure condition and the second exposure condition determined by the exposure condition determination means ;
The exposure condition determining means presets a step number difference between the number of exposure steps corresponding to the exposure condition calculated based on the first luminance value and the number of exposure steps corresponding to the exposure condition calculated based on the second luminance value. When the step number threshold is exceeded, the exposure step number corresponding to the exposure condition calculated based on the second luminance value is adjusted so that the step number difference is equal to or less than the step number threshold value, and the exposure step number corresponding to the exposure step number after the adjustment is adjusted. An imaging apparatus characterized in that a condition is determined as the second exposure condition . The exposure condition determining means, when there is a brightness value in which the numerical difference between the brightness values detected by the brightness value detecting means and the average value of the brightness values exceeds a preset abnormality threshold value, to claim 1, characterized in that determining the rest of the first exposure condition and the second exposure condition based on the first luminance value and the second luminance value in the respective luminance values excluding the brightness values greater than The imaging device described. Wherein the first luminance value is pre Symbol maximum luminance value, the imaging apparatus according to claim 1 or claim 2, wherein said second luminance value is pre SL minimum luminance value. A luminance value detection step for measuring a subject image formed on a light receiving surface of an image sensor for each of a plurality of divided areas and detecting a luminance value for each area;
The maximum brightness value of each brightness value detected in the brightness value detection step or the brightness value of high brightness according to the maximum brightness value is set as the first brightness value, and the first exposure condition is set based on the first brightness value. And determining the second exposure condition based on the second luminance value, using the minimum luminance value of the luminance values or a low luminance value corresponding to the minimum luminance value as the second luminance value. An exposure condition determination step to be performed;
A combined image generating step of generating a single combined image by combining the captured images captured in accordance with the first exposure condition and the second exposure condition determined in the exposure condition determining step ;
In the exposure condition determining step, a step number difference between an exposure step number corresponding to the exposure condition calculated based on the first luminance value and an exposure step number corresponding to the exposure condition calculated based on the second luminance value is set in advance. When the step number threshold is exceeded, the exposure step number corresponding to the exposure condition calculated based on the second luminance value is adjusted so that the step number difference is equal to or less than the step number threshold value, and the exposure step number corresponding to the exposure step number after the adjustment is adjusted. An imaging method , wherein a condition is determined as the second exposure condition .

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