Imaging device

Abstract

To suppress deterioration of image quality due to image processing performed to suppress deterioration of a luminance in a low luminance region, in exposure control for making the luminance in a high luminance region close to a target luminance.SOLUTION: An imaging apparatus comprises: first exposure control means which performs first exposure control for suppressing halation of a captured image; image processing means which on the basis of a control amount of the first exposure control, performs image processing for suppressing deterioration of a luminance in a low luminance region of the image; and second exposure control means which performs second exposure control for making a luminance in a high luminance region of a captured image close to a target luminance set by a user. When the second exposure control is performed, the first exposure control means does not perform the first exposure control.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image pickup apparatus. [Background Art]

[0002] Patent Document 1 discloses a technique of reducing exposure so as to suppress blown-out highlights in a captured image, and compensating for luminance reduction in a low-luminance region caused by the reduced exposure through gamma processing. Patent Document 2 discloses a technique that uses highlight-weighted photometry, which performs photometry on a high-luminance region of an image, to bring the luminance of the high-luminance region close to a target luminance set by a user. By combining these two techniques, it is possible to bring the luminance of a high-luminance region close to the target luminance while suppressing luminance reduction in a low-luminance region. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2010-193098 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2015-166767 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] However, simply combining the two techniques described above may result in a reduction in image quality. For example, gamma processing (image processing) that compensates for (suppresses) luminance reduction in a low-luminance region, and exposure reduction (exposure control) that brings the luminance of a high-luminance region close to the target luminance may cause the luminance of the low-luminance region and the luminance of the high-luminance region to become close to each other. As a result, an image with low contrast (a hazy image with poor visibility) may be obtained.

[0005] The present invention aims to provide a technology that can suppress the degradation of image quality caused by image processing that suppresses the decrease in brightness in low-brightness areas when performing exposure control to bring the brightness of high-brightness areas closer to the target brightness. [Means for solving the problem]

[0006] A first aspect of the present invention is an imaging device comprising: a first exposure control means for performing a first exposure control to suppress overexposure in an image; an image processing means for performing image processing to suppress a decrease in brightness in low-brightness regions of the image based on the control amount of the first exposure control; and a second exposure control means for performing a second exposure control to bring the brightness of high-brightness regions of an image closer to a target brightness set by the user, wherein when the second exposure control is performed, the first exposure control means does not perform the first exposure control.

[0007] A second aspect of the present invention includes a first exposure control means for performing a first exposure control to suppress overexposure in an captured image, an image processing means for performing image processing to suppress a decrease in brightness in low-brightness regions of the image based on the control amount of the first exposure control, and a second exposure control means for performing a second exposure control to bring the brightness of high-brightness regions of the captured image closer to a target brightness set by the user, wherein when the second exposure control is performed, before The first exposure control means controls the amount of the first exposure control when the second exposure control is not performed. The first exposure control This imaging device is characterized by determining the control amount by reducing it according to the target brightness.

[0008] A third aspect of the present invention is a first setting means for setting whether or not to perform a first exposure control to suppress overexposure in an captured image, and the luminance of the high-luminance region of the captured image by the user The imaging device includes a second setting means for setting whether or not to perform a second exposure control to approach a set target brightness, and a recording means for recording a captured image on a recording medium, wherein the first brightness, which is the brightness of the low-brightness region of a captured image recorded without the first and second exposure controls, and the second brightness, which is the brightness of the low-brightness region of a captured image recorded with the first exposure control but without the second exposure control, are approximately equal, and the third brightness, which is the brightness of the low-brightness region of a captured image recorded with the first and second exposure controls, is lower than the first and second brightness.

[0009] A fourth aspect of the present invention is a control method for an imaging device, comprising the steps of: performing a first exposure control to suppress overexposure in an image; and performing image processing to suppress a decrease in brightness in low-brightness regions of the image based on the control amount of the first exposure control, wherein a second exposure control can be performed to bring the brightness of high-brightness regions of the image closer to a target brightness set by the user, and the first exposure control is not performed when the second exposure control is performed.

[0010] A fifth aspect of the present invention includes the steps of performing a first exposure control to suppress overexposure in an captured image, and performing an image processing to suppress a decrease in brightness in low-brightness regions of the image based on the control amount of the first exposure control, wherein a second exposure control can be performed to bring the brightness of high-brightness regions of the captured image closer to a target brightness set by the user, and when the second exposure control is performed ,before The control amount for the first exposure control is the amount when the second exposure control is not performed. The first exposure control This is a control method for an imaging device, characterized in that the control amount is determined by reducing it according to the target brightness.

[0011] A sixth aspect of the present invention is a program for causing a computer to function as one of the means of the imaging apparatus described above. A seventh aspect of the present invention is a computer-readable storage medium that stores a program for causing a computer to function as one of the means of the imaging apparatus described above. Effects of the Invention

[0012] According to the present invention, when performing exposure control that brings the luminance of a high-luminance region close to a target luminance, it is possible to suppress degradation in image quality caused by performing image processing that suppresses a decrease in luminance in a low-luminance region. Brief Description of the Drawings

[0013] [Figure 1] It is a block diagram showing the configuration of the digital camera according to the present embodiment. [Figure 2] It is a diagram showing a selection screen according to the present embodiment. [Figure 3] It is a diagram showing a plurality of blocks of an image according to the present embodiment. [Figure 4] It is a diagram showing an image according to the present embodiment. [Figure 5] It is a schematic diagram showing a luminance histogram of an image according to the present embodiment. [Figure 6] It is a flowchart showing processing according to the present embodiment. [Figure 7] It is a diagram showing the correspondence between target luminance and correction coefficients according to the present embodiment. Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0015] <Configuration of Digital Camera> FIG. 1 is a block diagram showing the configuration of a digital camera 100, which is an example of an imaging device according to the present embodiment. As an imaging mechanism, the digital camera 100 includes a photographing lens 101, an aperture and shutter 102, an automatic exposure (AE) processing unit 103, a focus lens 104, an auto f ocus (AF) processing unit 105, an image sensor 106, and an A / D conversion unit 107.

[0016] The photographing lens 101 has a zoom mechanism. The aperture and shutter 102 control the amount of incident light, which is reflected light from a subject, entering the image sensor 106 and the charge accumulation time in accordance with instructions from the AE processing unit 103. The AE processing unit 103 controls exposure by controlling the operations of the aperture and shutter 102. The AE processing unit 103 also controls the A / D conversion unit 107. The focus lens 104 forms an optical image focused on the light-receiving surface of the image sensor 106 in accordance with a control signal from the AF processing unit 105. The AF processing unit 105 also calculates distance information from the digital camera 100 to the subject.

[0017] The image sensor 106 converts an optical image formed on the light-receiving surface into an electrical signal by a photoelectric conversion element such as a CCD element or a CMOS element, and outputs the electrical signal to the A / D conversion unit 107. The A / D conversion unit 107 converts the received electrical signal (analog signal) into a digital signal (RAW signal). The A / D conversion unit 107 includes a CDS circuit that removes noise from the received electrical signal and a non-linear amplification circuit that performs non-linear amplification on the received electrical signal before converting it into a digital signal.

[0018] The digital camera 100 further includes an image processing unit 108, an image recognition unit 109, a format conversion unit 110, and a DRAM (Dynamic RAM) 111.

[0019] The image processing unit 108 performs development processing. In development processing, for example, predetermined image processing (such as resizing processing including pixel interpolation or image reduction, and color conversion processing) is performed on the digital signal input from the A / D conversion unit 107. The image processing unit 108 also adjusts image quality by performing white balance (WB) adjustment and gradation correction for increasing or decreasing the brightness (brightness level) of an image on the digital signal input from the A / D conversion unit 107. For example, the image processing unit 108 increases or decreases the brightness with a uniform amplification factor over the entire image, or converts the brightness according to the level of the original brightness. The image processing unit 108 can also perform gradation correction processing corresponding to a scene based on the recognition result obtained by the image recognition unit 109.

[0020] The image recognition unit 109 can receive image data processed by the image processing unit 108. The image recognition unit 109 can recognize the brightness of the input image by performing photometry (photometric processing). For example, the image recognition unit 109 can set multiple regions in the image and perform photometry for each region. This allows the image recognition unit 109 to obtain photometric results for each region and determine high-brightness regions. The photometric results (including the results of determining high-brightness regions) are output to the AE processing unit 103.

[0021] Furthermore, the image recognition unit 109 can recognize (identify) scenes using known techniques. The image recognition unit 109 can detect faces, upper bodies, or entire bodies of animals such as people, dogs, cats, or birds from an image, or detect vehicles such as cars or motorcycles, and recognize a scene based on the detected subjects. For example, if the image recognition unit 109 detects a person's face, it can recognize that it is a scene in which a person is being photographed. Also, if the image recognition unit 109 detects multiple cars driving side by side, it can recognize that it is a scene of motorsport. The scene information recognized by the image recognition unit 109 is output to the AE processing unit 103.

[0022] The user can select a metering mode by operating the control unit 116. The control unit 116 notifies the AE processing unit 103 of the metering mode selected by the user. The AE processing unit 103 performs automatic exposure (AE) processing based on the metering results acquired by the image recognition unit 109, the scene information recognized by the image recognition unit 109, and the metering mode selected by the user. .

[0023] Furthermore, the image recognition unit 109 can recognize the focus status of the input image. The AF processing unit 105 performs autofocus (AF) processing based on the recognition result of the focus status. The image recognition unit 109 can also generate a luminance histogram of the input image. The image processing unit 108 performs gradation correction processing corresponding to the scene based on the generated luminance histogram.

[0024] The format conversion unit 110 converts the format of the image data generated by the image processing unit 108 in order to store the image data in the DRAM 111. The DRAM 111 is an internal memory and is used, for example, as a buffer for temporarily storing image data or as working memory in image data compression / decompression processing.

[0025] The digital camera 100 also includes an image recording unit 112, a system control unit 113, a VRAM (Video RAM) 114, a display unit 115, an operation unit 116, a main switch (main SW) 117, and a shooting switch (shooting SW) 118.

[0026] The image recording unit 112 has a recording medium (e.g., a memory card) for storing captured images (still images or videos) and an interface thereto.

[0027] The system control unit 113 includes a CPU (processor), ROM, and RAM. The CPU controls the overall operation of the digital camera 100 by loading and executing programs stored in ROM into the RAM's work area. For example, the system control unit 113 switches the mode of the image sensor 106 between a predetermined number of imaging drive modes. VRAM 114 is memory for image display.

[0028] The display unit 115 is, for example, an LCD (Liquid Crystal Display). The display unit 115 can display images, provide operational assistance, and display the status of the digital camera 100. During shooting, the display unit 115 displays the shooting screen and the distance measurement area on the shooting screen. The display unit 115 can also display a selection screen for the user to select (specify) a target brightness in the high-brightness area. Figure 2 shows an example of a selection screen. The method by which the user selects a target brightness using the selection screen will be described later.

[0029] The control unit 116 is a component for the user to operate the digital camera 100. By operating the control unit 116, the user can perform various settings, such as exposure compensation, aperture value setting, and image playback settings. The control unit 116 has a menu switch, a zoom lever for instructing the zoom operation of the shooting lens, and an operation mode switch for switching the operation mode between shooting mode and playback mode.

[0030] As described above, the user can select a metering mode by operating the control unit 116. The metering modes selectable by the user include, for example, evaluative metering mode, partial metering mode, and highlight-weighted metering mode.

[0031] Evaluative metering mode measures light in each of several predefined areas of the captured image and determines the final exposure based on information about the subject's brightness distribution, color, distance, and composition. Evaluative metering mode is suitable for general shooting, including backlit shots. Partial metering mode measures light in the central part of the image. Partial metering mode is effective when there is strong light around the subject (for example, a backlit scene). Highlight-weighted metering mode measures light in the high-brightness areas of the image. Generally, based on the metering results in highlight-weighted metering mode, the exposure is adjusted so that the high-brightness areas are at the correct brightness. When this control is applied, the resulting image will be darker than when exposure control is performed based on the metering results of the evaluative metering mode.

[0032] Furthermore, the user can select a target brightness for the high-brightness region by operating the control unit 116. The target brightness selected by the user is output to the AE processing unit 103 and used for exposure control. The target brightness is also output to the image processing unit 108 and used for image processing control.

[0033] The main switch 117 is a switch for turning on the power supply to the digital camera 100. The shooting switch 118 is a switch that allows two-stage operation depending on the depth of pressing. When a half-press operation (SW1 operation, shooting preparation instruction) that presses the shooting switch 118 halfway is performed, the system control unit 113 performs a shooting preparation operation including AE processing and AF processing. When a full-press operation (SW2 operation, shooting instruction) that presses the shooting switch 118 all the way down is performed, the system control unit 113 performs shooting processing.

[0034] A series of processes performed by the digital camera 100 will be described. When the digital camera 100 is powered on by pressing the main switch 117, the digital camera 100 enters a shooting standby state (a state in which imaging processing is performed at a predetermined cycle (for example, a 33 ms cycle) by the image sensor 106, and captured images are sequentially displayed on the display unit 115). When the shooting switch 118 is pressed (SW2 operation), main imaging processing is performed by the image sensor 106, and an image (image data) obtained by the main imaging processing is subjected to image processing by the image processing unit 108 and then recorded in the image recording unit 112. Thereafter, the digital camera 100 returns to the shooting standby state again. When the main switch 117 is pressed again, the power of the digital camera 100 is turned off.

[0035] <D+ correction> The digital camera 100 is capable of executing exposure control that suppresses (reduces) blown-out highlights in a captured image, and image processing (gradation correction) that suppresses a decrease in luminance in low-luminance regions of the image based on the control amount. Hereinafter, the combination of this exposure control and image processing is referred to as D+ correction. Known techniques, for example, the technique disclosed in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2010-193098) can be used for D+ correction. By performing D+ correction, in a scene where a low-luminance subject and a high-luminance subject coexist, blown-out highlights (saturation) of the high-luminance subject can be suppressed while maintaining the brightness of the low-luminance subject. Although the low-luminance region is not particularly limited, it is, for example, a region composed of one or more pixels whose luminance is equal to or less than a threshold value. The threshold value is, for example, the luminance at the center of the possible range of luminance (dynamic range), or a luminance lower than that.

[0036] Normally, before shooting, shooting conditions such as aperture value, shutter speed, and gain are set (determined) to ensure that the image is taken with appropriate exposure, depending on the brightness information of the subject and whether or not there is a person's face. However, the dynamic range of the captured image is not wide, and for example, in a backlit scene where the subject is photographed with the sun behind it, the brightness of the bright background will saturate and overexposure will occur, regardless of the shooting conditions set.

[0037] In D+ correction, the system control unit 113 uses the AE processing unit 103 to set (change) the exposure value to an underexposed value to prevent overexposure. Furthermore, the system control unit 113 uses the image processing unit 108 to perform image processing to increase the brightness of the low-luminance areas of the captured image. This image processing is, for example, gamma processing using a gamma curve. Generally, the decrease in brightness of the low-luminance areas due to the reduced exposure is compensated for, and image processing is performed so that the brightness of the low-luminance areas becomes equivalent to that of when the exposure is correct. This makes it possible to maintain the brightness of low-luminance subjects while suppressing (reducing) overexposure of the background.

[0038] The system control unit 113 determines, for example, the amount of exposure change in D+ compensation (the amount of exposure control and the amount of D+ compensation) according to the brightness of the scene. An example is described below.

[0039] First, the system control unit 113 sets multiple regions (multiple blocks) in the image (through image) obtained by periodic imaging processing in the shooting standby state, and acquires a representative brightness for each block. Here, it is assumed that the through image is obtained while exposure control (normal exposure control) is being performed to bring the average brightness of the entire image closer to a predetermined brightness. Figure 3 shows an example of multiple blocks. In Figure 3, multiple blocks are set in a part of the image, but the entire area of ​​the image may be divided into multiple blocks. The representative brightness of a block is, for example, the average brightness, maximum brightness, minimum brightness, intermediate brightness, or most frequent brightness of that block. In this embodiment, the representative brightness is assumed to be the average brightness.

[0040] Next, the system control unit 113 counts the number of blocks (saturated blocks) where the average brightness has reached the saturation value (upper limit) of 255. The system control unit 113 lowers the exposure according to the number of saturated blocks. For example, the system control unit 113 lowers the exposure by a larger amount the more saturated blocks there are. At this time, the system control unit 113 changes the setting of the gamma curve according to the amount of exposure reduction so that the brightness of the low-brightness region of the through image does not change.

[0041] Then, the system control unit 113 counts the number of saturated blocks in the captured through image again.

[0042] The system control unit 113 repeatedly counts the saturation blocks and reduces the exposure until the number of saturation blocks becomes 0. When the number of saturation blocks becomes 0, the system control unit 113 determines the total amount of exposure reduction as the D+ compensation amount for the current scene (a provisional D+ compensation amount, described later).

[0043] <Highlight-focused exposure control> The digital camera 100 is also capable of performing highlight-weighted exposure control. Highlight-weighted exposure control is an exposure control that brings the brightness of the high-brightness areas of the captured image closer to a target brightness set by the user, and is performed in highlight-weighted metering mode. Known techniques, such as the technique disclosed in Patent Document 2 (Japanese Patent Application Publication No. 2015-166767), can be used for highlight-weighted exposure control. An example is described below.

[0044] For example, the system control unit 113 displays the selection screen (user interface) shown in Figure 2 on the display unit 115, allowing the user to select a target brightness for the high-brightness area from the options TH1, TH2, and TH3. By selecting (specifying) a target brightness, the user can adjust the brightness of the high-brightness area in the captured image to match their intended brightness. The number of options may be more or less than three.

[0045] When the photography switch 118 is pressed (SW2 operation), the system control unit 113 sets a plurality of blocks for the through image obtained at that time, and acquires representative luminance for each block. As described above, in the present embodiment, it is assumed that the representative luminance is average luminance.

[0046] Next, the system control unit 113 selects, from among the plurality of blocks, the block having the highest average luminance as a high-luminance region (highlight portion).

[0047] Then, the system control unit 113 converts the target luminance and the luminance of the high-luminance region into signal values before gamma processing by performing inverse gamma processing (inverse transformation of gamma processing), and calculates an exposure step between the two obtained signal values. As the exposure step, for example, an APEX value (Additi ve system of Photographic EXposure) difference is calculated. Assuming that a linear signal value of the target luminance before gamma processing is a signal value Ya, and a linear signal value of the luminance of the high-luminance region before gamma processing is a signal value Yb, the exposure step between the signal value Ya and the signal value Yb can be calculated by Log(Ya / Yb).

[0048] Here, it is assumed that 200 is selected as the JPEG luminance (tone value of a JPEG image) which is the target luminance, and the luminance of the high-luminance region is 240. Assuming that the signal value Ya corresponding to the target luminance 200 is 5000, and the signal value Yb corresponding to the luminance 240 of the high-luminance region is 10000, Log(Ya / Yb) = -1. Therefore, the system control unit 113 can bring the luminance of the high-luminance region closer to the target luminance by increasing the exposure value of the aperture and shutter 102 by one step from the current value. In this way, the system control unit 113 can control exposure such that the luminance of the high-luminance region substantially matches the target luminance specified by the user in accordance with the exposure step between the signal value Ya and the signal value Yb (the exposure step between the target luminance and the luminance of the highlight portion).

[0049] <Problems Caused by the Combination of D+ Correction and Highlight-Priority Exposure Control> By combining D+ compensation and highlight-weighted exposure control, it is possible to maintain the brightness of low-light areas at the same level as normal exposure control while bringing the brightness of high-light areas closer to the target brightness specified by the user. However, simply combining D+ compensation and highlight-weighted exposure control can sometimes result in a decrease in image quality. An example is explained below using Figures 4(A), 4(B), and 5(A) to 5(C).

[0050] Figure 4(A) shows an example of an image taken with normal exposure control applied. The image in Figure 4(A) is a scene in which the sky and a tree backlit by the light are included in the field of view. Figure 5(A) shows the luminance histogram (luminance distribution) of the image in Figure 4(A). In Figure 5(A), by applying normal exposure control based on the average luminance of the entire image, the luminance of the sky area (an area with relatively high luminance) reaches the saturation value of 255.

[0051] By applying D+ correction, as shown in Figure 5(B), it is possible to reduce overexposure in the sky area while maintaining the brightness of the tree area (low-luminance area).

[0052] When highlight-weighted exposure control is performed in the state shown in Figure 5(B), the brightness of the high-brightness area (maximum brightness) can be reduced to a target brightness of 200 specified by the user, as shown in Figure 5(C).

[0053] However, in Figure 5(C), the brightness of the tree region and the brightness of the sky region are close. As a result, as shown in Figure 4(B), a low-contrast image (a hazy image with poor visibility) is obtained. The larger the D+ correction amount, or the lower the target brightness, the closer the brightness of the low-brightness region and the high-brightness region become, and the more pronounced the decrease in contrast becomes.

[0054] <Solutions to problems arising from combinations> Figure 6 is a flowchart illustrating an example of processing performed by the digital camera 100. The processing in Figure 6 includes D+ compensation and highlight-weighted exposure control, and according to the processing in Figure 6, the above-mentioned problems arising from the combination of D+ compensation and highlight-weighted exposure control can be solved. The details will be described later. For example, when the digital camera 100 is powered on and enters a shooting standby state, the processing in Figure 6 begins.

[0055] In step S601, the system control unit 113 prompts the user to specify a target brightness for the high-brightness area using the method described above, and obtains the target brightness specified by the user.

[0056] In step S602, the system control unit 113 calculates the D+ correction amount from the through image using the method described above, and determines the calculated D+ correction amount as a provisional D+ correction amount.

[0057] In step S603, the system control unit 113 determines the final D+ correction amount by reducing the provisional D+ correction amount according to the target brightness acquired in step S601. For example, the system control unit 113 reduces the provisional D+ correction amount using a correction coefficient pre-associated with the target brightness acquired in step S601. A value greater than 0 and less than 1 is used as the correction coefficient. As mentioned above, the larger the D+ correction amount or the lower the target brightness, the more pronounced the decrease in contrast becomes; therefore, a smaller correction coefficient is used for lower target brightness. The correction coefficient to be used is determined, for example, using a table or function that shows the correspondence between target brightness and correction coefficient. The ROM of the system control unit 113 may have a table (three correction coefficients corresponding to three target brightness options (three brightness levels that can be set as target brightness)) pre-stored in it, as shown in Figure 7. As mentioned above, the number of options may be more or less than three.

[0058] The method for reducing the provisional D+ correction amount is not limited to the method described above. For example, the system control unit 113 may reduce the provisional D+ correction amount using a function that takes the target brightness as the input value and the final D+ correction amount as the output value. The system control unit 113 may choose not to perform D+ correction if the target brightness is lower than a predetermined threshold. The system control unit 113 may also choose not to perform D+ correction if highlight-weighted exposure control is performed, regardless of whether the target brightness is lower than a predetermined threshold.

[0059] Furthermore, if highlight-weighted exposure control is not performed, the process of reducing the provisional D+ compensation amount is not carried out. Therefore, the provisional D+ compensation amount can be considered the final D+ compensation amount when highlight-weighted exposure control is not performed.

[0060] Furthermore, in step S603, the system control unit 113 controls the exposure and sets the gamma curve according to the final D+ compensation amount. The system control unit 113 applies the set gamma curve to the through image (the through image obtained with the exposure controlled according to the final D+ compensation amount).

[0061] In step S604, the system control unit 113 determines whether or not a shooting instruction (full press operation of the shooting switch 118, operation of SW2) has been given. If the system control unit 113 determines that there is no shooting instruction, it returns to step S601; if it determines that there is a shooting instruction, it proceeds to step S605.

[0062] In step S605, the system control unit 113 performs highlight-weighted exposure control in the manner described above. Here, highlight-weighted exposure control is performed on the through image to which D+ correction has been applied. For this reason, a gamma curve whose settings are changed according to the final D+ correction amount is used for inverse gamma processing. Since the D+ correction amount is reduced in step S603, the brightness of the high-luminance areas of the through image becomes higher compared to the case where the D+ correction amount is not reduced, and the amount of exposure reduction due to highlight-weighted exposure control becomes larger.

[0063] In step S606, the system control unit 113 acquires an image by performing the imaging process with the exposure determined in step S605 (with D+ correction and highlight-weighted exposure control applied).

[0064] In step S607, the system control unit 113 applies the gamma curve set in step S603 (a gamma curve corresponding to the final D+ correction amount) to the image acquired in step S606.

[0065] As described above, according to this embodiment, the final D+ correction amount is determined by reducing the provisional D+ correction amount according to the target brightness (or, if highlight-weighted exposure control is performed, D+ correction is omitted). This makes it possible to suppress the degradation of image quality caused by gamma processing included in D+ correction when performing highlight-weighted exposure control. For example, in the scenes of Figure 4(A) and Figure 5(A), reducing the D+ correction amount lowers the brightness of the tree area (low brightness area), and the brightness histogram of Figure 5(D) is obtained. In the brightness histogram of Figure 5(D), it can be seen that the brightness of the tree area and the brightness of the sky area are far apart, and an image with high contrast is obtained.

[0066] Here, the system control unit 113 can set whether or not to perform D+ correction and whether or not to perform highlight-weighted exposure control. For example, the system control unit 113 makes these settings in response to instructions from the user. In this case, according to this embodiment, the following relationships hold. In the following relationships, the first brightness is the brightness of the low-brightness region of the captured image recorded without D+ correction and highlight-weighted exposure control (normal exposure control is performed). The second brightness is the brightness of the low-brightness region of the captured image recorded with D+ correction but without highlight-weighted exposure control. The third brightness is the brightness of the low-brightness region of the captured image recorded with D+ correction and highlight-weighted exposure control. The first brightness and the second brightness are approximately equal. • The third brightness level is lower than the first and second brightness levels.

[0067] The above embodiments (including modified examples) are merely examples, and configurations obtained by appropriately modifying or changing the configuration of the above embodiments within the scope of the gist of the present invention are also included in the present invention. Configurations obtained by appropriately combining the configurations of the above embodiments are also included in the present invention.

[0068] <Other Embodiments> The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0069] This embodiment includes the following configurations, methods, programs, and media. (Composition 1) A first exposure control means that performs a first exposure control to suppress overexposure in the captured image, Image processing means that performs image processing to suppress brightness reduction in low-luminance areas of the image based on the control amount of the first exposure control, A second exposure control means performs a second exposure control to bring the brightness of the high-brightness areas of the captured image closer to a target brightness set by the user. It has, When the second exposure control is performed, the first exposure control means does not perform the first exposure control. An imaging device characterized by the following features. (Configuration 2) A first exposure control means that performs a first exposure control to suppress overexposure in the captured image, Image processing means that performs image processing to suppress brightness reduction in low-luminance areas of the image based on the control amount of the first exposure control, A second exposure control means performs a second exposure control to bring the brightness of the high-brightness areas of the captured image closer to a target brightness set by the user. It has, When the second exposure control is performed, The second exposure control means performs the second exposure control after the first exposure control. The first exposure control means determines the control amount of the first exposure control by reducing the control amount when the second exposure control is not performed according to the target brightness. An imaging device characterized by the following features. (Composition 3) When the second exposure control is performed, the image processing means performs the image processing on the image captured after the second exposure control is performed. The imaging apparatus according to configuration 2, characterized in that... (Composition 4) The first exposure control means reduces the amount of control when the second exposure control is not performed by a coefficient that is pre-associated with the target brightness. The imaging apparatus according to configuration 2 or 3, characterized by the features described herein. (Composition 5) A storage means that stores in advance multiple coefficients corresponding to multiple brightness levels that can be set as the target brightness level. Furthermore, it has The imaging apparatus according to configuration 4, characterized by the features described above. (Composition 6) The first exposure control means does not perform the first exposure control if the target brightness is lower than the threshold. An imaging device according to any one of configurations 2 to 5, characterized in that it is an imaging device. (Composition 7) A first setting means for setting whether or not to perform a first exposure control to suppress overexposure in the captured image, A second setting means for setting whether or not to perform a second exposure control to bring the brightness of the high-brightness areas of the captured image closer to a target brightness set by the user, A recording means for recording captured images onto a recording medium and It has, The first brightness, which is the brightness of the low-brightness region of the captured image recorded without the first exposure control and the second exposure control, and the second brightness, which is the brightness of the low-brightness region of the captured image recorded with the first exposure control but without the second exposure control, are approximately equal. The third brightness, which is the brightness of the low-brightness region of the captured image recorded after the first and second exposure controls have been performed, is lower than the first brightness and the second brightness. An imaging device characterized by the following features. (Method 1) The first step is to perform exposure control to suppress overexposure in the captured image, The steps include: performing image processing to suppress brightness reduction in low-luminance areas of the image based on the control amount of the first exposure control; It has, A second exposure control is possible to bring the brightness of the high-brightness areas of the captured image closer to a target brightness set by the user. When the second exposure control is performed, the first exposure control is not performed. A control method for an imaging device, characterized by the following: (Method 2) The first step is to perform exposure control to suppress overexposure in the captured image, The steps include: performing image processing to suppress brightness reduction in low-luminance areas of the image based on the control amount of the first exposure control; It has, A second exposure control is possible to bring the brightness of the high-brightness areas of the captured image closer to a target brightness set by the user. When the second exposure control is performed, The second exposure control is performed after the first exposure control. The amount of control for the first exposure control is determined by reducing the amount of control when the second exposure control is not performed, according to the target brightness. A control method for an imaging device, characterized by the following: (program) A program for causing a computer to function as one of the means of the imaging apparatus described in any one of configurations 1 to 7. (medium) A computer-readable storage medium containing a program for causing the computer to function as one of the means of the imaging apparatus described in any one of items 1 to 7. [Explanation of Symbols]

[0070] 100: Digital camera 113: System control unit

Claims

1. A first exposure control means that performs a first exposure control to suppress overexposure in the captured image, Image processing means that performs image processing to suppress brightness reduction in low-luminance areas of the image based on the control amount of the first exposure control, A second exposure control means performs a second exposure control to bring the brightness of the high-brightness region of the captured image closer to a target brightness set by the user. It has, When the second exposure control is performed, the first exposure control means does not perform the first exposure control. An imaging device characterized by the following features.

2. A first exposure control means that performs a first exposure control to suppress overexposure in the captured image, Image processing means that performs image processing to suppress brightness reduction in low-luminance areas of the image based on the control amount of the first exposure control, A second exposure control means performs a second exposure control to bring the brightness of the high-brightness region of the captured image closer to a target brightness set by the user. It has, When the second exposure control is performed, the first exposure control means determines the control amount of the first exposure control by reducing the control amount of the first exposure control when the second exposure control is not performed according to the target brightness. An imaging device characterized by the following features.

3. When the second exposure control is performed, the image processing means performs the image processing on the image captured after the second exposure control is performed. The imaging device according to feature 2.

4. The image processing is gamma processing using a gamma curve. The imaging device according to feature 3.

5. The first exposure control means controls the second exposure using a coefficient pre-associated with the target brightness. The control amount is reduced when output control is not performed. The imaging device according to feature 2.

6. A storage means that stores in advance multiple coefficients corresponding to multiple brightness levels that can be set as the target brightness level. Furthermore, it has The imaging apparatus according to feature 5.

7. The first exposure control means does not perform the first exposure control if the target brightness is lower than the threshold. The imaging device according to feature 2.

8. A first setting means for setting whether or not to perform a first exposure control to suppress overexposure in the captured image, A second setting means for setting whether or not to perform a second exposure control to bring the brightness of the high-brightness areas of the captured image closer to a target brightness set by the user, A recording means for recording captured images onto a recording medium and It has, The first brightness, which is the brightness of the low-brightness region of the captured image recorded without the first exposure control and the second exposure control, and the second brightness, which is the brightness of the low-brightness region of the captured image recorded with the first exposure control but without the second exposure control, are approximately equal. The third brightness, which is the brightness of the low-brightness region of the captured image recorded after the first and second exposure controls are performed, is lower than the first and second brightness levels. An imaging device characterized by the following features.

9. The first step is to perform exposure control to suppress overexposure in the captured image, The steps include: performing image processing to suppress brightness reduction in low-luminance areas of the image based on the control amount of the first exposure control; It has, A second exposure control is possible to bring the brightness of the high-brightness areas of the captured image closer to a target brightness set by the user. When the second exposure control is performed, the first exposure control is not performed. A control method for an imaging device, characterized by the following:

10. The first step is to perform exposure control to suppress overexposure in the captured image, The steps include: performing image processing to suppress brightness reduction in low-luminance areas of the image based on the control amount of the first exposure control; It has, A second exposure control is possible to bring the brightness of the high-brightness areas of the captured image closer to a target brightness set by the user. When the second exposure control is performed, the control amount of the first exposure control is determined by reducing the control amount of the first exposure control when the second exposure control is not performed, according to the target brightness. A control method for an imaging device, characterized by the following:

11. A program for causing a computer to function as one of the means of an imaging apparatus according to any one of claims 1 to 8.

12. A computer-readable storage medium storing a program for causing a computer to function as one of the means of an imaging apparatus according to any one of claims 1 to 8.

Images