JP6670110B2 - Image processing apparatus, imaging apparatus, control method, and program - Google Patents

Description

  The present invention relates to an image processing apparatus, an image capturing apparatus, a control method, and a program, and more particularly to a technique for changing the dynamic range and performing photographing with different gradation expressions.

  2. Description of the Related Art In an imaging apparatus such as a digital camera that performs image capturing by exposing an image capturing element, electric charge accumulated in a photoelectric conversion element of the image capturing element in one imaging operation is saturated due to brightness of an object and exposure setting. This can lead to a result in which gradation expression such as so-called overexposure is lost in the region. On the other hand, in recent years, by using an image signal captured with a low exposure amount, a dynamic range (DR) for precisely reproducing the brightness distribution of a subject to a signal level while leaving a gradation expression in a high luminance area. Extended technologies exist. Since the image signal obtained in this manner has a low exposure amount and is entirely dark, by applying gamma correction, the overall luminance is raised so that the gradation expression in the high luminance region is secured. Patent Literature 1 discloses a gamma characteristic in which a low-to-medium luminance region where a main subject is present is adjusted so as to have the same luminance expression as when DR is not extended, and a compression ratio is increased for a high luminance region. Is used for gamma correction, and an image in which DR is extended is output.

JP 2004-120511 A

  On the other hand, a plurality of selectable DRs are provided, and in an imaging apparatus that performs imaging with an imaging setting corresponding to the selected DR, an output image signal having saturated pixels can be generated. For example, when imaging is performed with the imaging setting related to the DR selected by the user, the brightness (may be brightness, photometric value, or the like) of the subject existing in the imaging range is not included in the selected DR. If this is the case, the gradation expression relating to the subject is lost (high cut state).

  However, even if the output image signal after the gamma correction is presented using a display device and the user can make a configuration that can be confirmed before shooting, for example, it is determined whether or not the gradation expression in the high-luminance area is performed in the DR. It was difficult to visually confirm.

  SUMMARY An advantage of some aspects of the invention is to provide an image processing device, an imaging device, a control method, and a program that enable a user to set a suitable dynamic range.

In order to achieve the above object, an image processing apparatus according to the present invention includes: a selection unit that selects one exposure setting from a plurality of exposure settings each corresponding to a different dynamic range; and an exposure unit that is selected by the selection unit. Based on an image signal obtained by imaging with an exposure setting corresponding to a second dynamic range having a range wider than the first dynamic range corresponding to the setting, brightness of a predetermined area of the image signal is obtained. When the brightness of the predetermined area acquired by the acquiring means is not included in the first dynamic range, the presenting means presents information for recognizing the user to that effect. I do.

  According to the present invention having such a configuration, it becomes possible for a user to set a suitable dynamic range.

External view of digital video camera 100 according to an embodiment of the present invention FIG. 1 is a block diagram showing a functional configuration of a digital video camera 100 according to an embodiment of the present invention. 9 is a flowchart illustrating a presentation process performed by the digital video camera 100 according to the first embodiment of the present invention. FIG. 4 is a diagram for explaining a gamma characteristic for generating a display image signal in the DR assist function according to the embodiment of the present invention. FIG. 4 is a diagram for explaining photometric values acquired according to the first embodiment of the present invention. Screen configuration example of information presentation according to the first embodiment of the present invention 9 is a flowchart illustrating a presentation process according to the second embodiment of the present invention. Screen configuration example of information presentation according to Embodiment 2 and Modification 1 of the present invention

[Embodiment]
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. Note that an embodiment described below is an example of an image processing apparatus that includes a digital video camera capable of performing imaging using a plurality of exposure settings each corresponding to a different dynamic range (hereinafter, DR). An example to which the invention is applied will be described. However, the present invention is applicable to any device capable of presenting information that can be a reference when selecting the plurality of exposure settings.

<< Configuration of Digital Video Camera 100 >>
FIG. 1 is a diagram showing an appearance of a digital video camera 100 according to an embodiment of the present invention.

  In FIG. 1, a display unit 28 is a display device provided to display image signals and various kinds of information captured and recorded in a plurality of photographing modes. Further, the digital video camera 100 is provided with a recording switch 61 for giving a shooting instruction, a mode switch 60 for switching various modes, and a power switch 72 for switching power on / off. In addition, an operation member that receives various operations from the user, such as various buttons and a cross key, is provided as the operation unit 70.

  The connector 112 is a connector for a connection cable for connecting the digital video camera 100 to an external device. The recording medium 200 is a detachably connected recording medium such as a memory card or a hard disk. The recording medium 200 is connected to the digital video camera 100 by being stored in the recording medium slot 201, so that information can be transmitted and received.

  Next, the functional configuration of the digital video camera 100 will be described with reference to the block diagram of FIG. As illustrated, in the digital video camera 100 of the present embodiment, light from a subject is guided to the imaging unit 22 through the barrier 102, the imaging lens 103, the aperture 101, and the ND 104 to obtain an imaging signal. The photographing lens 103 is a lens group including, for example, a zoom lens and a focus lens, and forms a subject image. The diaphragm 101 is a diaphragm used for adjusting the amount of light. The ND 104 is a filter used for dimming. The imaging unit 22 is an imaging device including a CCD, a CMOS device, or the like that converts the formed optical image into an electric signal (analog image signal). The imaging unit 22 also has functions such as control of the amount / time of charge storage by the electronic shutter, control of application of analog gain, and change of readout speed. The A / D converter 23 converts an analog signal output from the imaging unit 22 into a digital signal. The barrier 102 covers the imaging optical system including the imaging lens 103 to prevent the imaging lens including the imaging lens 103, the diaphragm 101, and the imaging unit 22 from being stained or damaged.

  The image processing unit 24 performs a color conversion process and a gamma correction process on the digital image signal (hereinafter simply referred to as an image signal or image data) output from the A / D converter 23 or the image data obtained by the memory control unit 15. And processing such as addition of digital gain. Further, the image processing unit 24 performs a predetermined calculation process related to exposure control or the like using the captured image signal, and transmits the calculation result to the system control unit 50. The system control unit 50 performs exposure control, distance measurement control, white balance control, and the like based on the calculation result. By operating in this manner, TTL (through the lens) type AF (auto focus) processing, AE (auto exposure) processing, AWB (auto white balance) processing, and the like are realized.

  The image processing unit 24 also generates an image signal (image signal for display) to be displayed on the display unit 28 described later. The image signal for display is not limited to an image signal obtained by imaging (including a signal to which various processes are applied), and is further determined in advance or generated according to the state of the digital video camera 100. One or more GUIs may be superimposed and configured. In the digital video camera 100 of the present embodiment, the image processing unit 24 converts an image signal obtained by superimposing, for example, iris information, STOP information, focus information, and the like at the time of imaging onto an image signal obtained by imaging as an image signal for display. Output.

  The digital video camera 100 according to the present embodiment is configured to be able to output a plurality of types of DR image signals, and a user changes an imaging setting (exposure setting) so that a desired DR image signal is output. be able to. The DR of the output image may be changed according to the selected shooting mode, or may be selected according to various types of change operations related to the exposure setting by the user. That is, the exposure settings that can be set in the digital video camera 100 include a plurality of exposure settings each corresponding to a different DR. Here, the plurality of exposure settings need not all correspond to different DRs, and does not exclude that there are a plurality of exposure settings corresponding to the same DR.

  By the way, whether or not the gradation desired by the user is performed in the DR selected as described above, that is, saturation occurs in the photoelectric conversion element and a part of brightness (photometric value) is expressed as a saturation value. It is difficult to confirm whether or not it will happen. Accordingly, the digital video camera 100 of the present embodiment has a DR setting assist function for presenting information for facilitating the determination of the imaging setting / exposure setting (or DR setting) for obtaining a desired imaging result to the user. Have. The DR setting assist function may be a function that can be additionally selected in a shooting mode such as a manual mode in which various settings relating to imaging can be changed.

  In the DR setting assist function, the image processing unit 24 includes the information in the display image signal as superimposed data in order to present the user with information for facilitating the DR setting of the image signal obtained by the imaging to the user. This is achieved by: That is, in the digital video camera 100 of the present embodiment, the information is presented to the user via the display unit 28 together with the image signal obtained by imaging. However, in the practice of the present invention, presentation of information for facilitating DR setting to the user need not be performed together with an image signal obtained by imaging, and if the information can be presented to the user. The medium used for display is not limited to the display unit 28. For example, the presentation of the information need not be performed by a GUI as described later, but may be performed by simply presenting a necessary numerical value. The information presentation is not limited to the display performed by the display device including the display unit 28 provided in the digital video camera 100, but may be performed using an external display device connected to the digital video camera 100. Needless to say, this may be done.

  Note that the various processes executed in the image processing unit 24 may be divided into arbitrary units, and the image processing unit 24 is configured by providing a dedicated arithmetic circuit or processor for each division unit process. May be used. In this case, each circuit or chip included in the image processing unit 24 is configured not to be under the control of the system control unit 50 but to start a predetermined operation according to a signal input and to output a signal as an operation result. It may be something.

  As described above, various output signals generated by the image processing unit 24 are directly written to the memory 32 via the memory control unit 15. The memory 32 is a storage area for temporarily storing a digital image signal captured by the imaging unit 22 and converted by the A / D converter 23. The memory 32 has a sufficient storage capacity to store moving images and sounds for a predetermined time. The memory 32 also serves as a storage device (video memory) for storing image signals for display relating to the display unit 28. In this case, the D / A converter 13 converts the display image signal stored in the memory 32 into an analog signal and supplies the analog signal to the display unit 28. In this way, the display image signal written in the memory 32 is displayed on the display unit 28.

  The display unit 28 is a display device such as an LCD, for example, and performs display according to the analog image signal output from the D / A converter 13. Further, the image signal once A / D converted by the A / D converter 23 and stored in the memory 32 is analog-converted in the D / A converter 13 and sequentially transferred to the display unit 28 for display. Reference numeral 28 functions as an electronic viewfinder, and can realize through image display.

  The nonvolatile memory 56 is, for example, an electrically erasable / recordable memory, and for example, an EEPROM is used. The nonvolatile memory 56 stores constants for operation of the system control unit 50, operation programs of each block of the digital video camera 100, and the like.

  The system control unit 50 is a control circuit such as a CPU, for example, and controls the operation of each block of the digital video camera 100. The system control unit 50 controls the operation of each block by reading, for example, the operation program of each block recorded in the non-volatile memory 56, and developing and executing the program in the system memory 52. The system memory 52 is, for example, a RAM or the like, and functions not only as a development area for an operation program but also as a storage area for storing intermediate data and the like output by the operation of each block. The system control unit 50 also performs display control by controlling the memory 32, the D / A converter 13, the display unit 28, and the like. The system timer 53 is used for a timekeeping function for measuring the time used for various controls and the time related to the built-in clock, and the system control unit 50 controls various processes using the timekeeping function as needed.

  The mode switch 60 receives an operation input for switching the operation mode of the system control unit 50 to any one of a moving image recording mode, a still image recording mode, a reproduction mode, and the like. The modes included in the moving image recording mode and the still image recording mode include the above-described normal mode and high brightness priority mode. In addition, it may include an auto shooting mode, an auto scene discrimination mode, a manual mode, various scene modes for setting shooting for each shooting scene, a program AE mode, a custom mode, and the like. Information on the mode change made by the mode changeover switch 60 is transmitted to the system control unit 50 as a predetermined control signal. The recording switch 61 receives an operation input for switching between a shooting standby state and a shooting state. The system control unit 50 starts a series of operations from signal reading from the imaging unit 22 to writing of moving image data to the recording medium 200 in response to receiving a control signal related to an operation input made to the recording switch 61.

  Each operation member of the operation unit 70 is appropriately assigned a function for each scene by, for example, selecting and operating various function icons displayed on the display unit 28, and receives operation inputs related to various functions. The various functions to which the buttons are assigned may include, for example, end, return, image advance, jump, refinement, attribute change, and the like. For example, when an operation input related to the menu button is performed, a menu screen on which various settings can be made is displayed on the display unit 28, and the assignment of the operation input received for each operation member of the operation unit 70 is changed. The user can intuitively perform various settings based on the menu screen displayed on the display unit 28 using the four-way up / down / left / right cross keys and the SET button. In the digital video camera 100 of the present embodiment, the user can move the pointer displayed on the display unit 28 with the cross key in a predetermined state. For example, by further operating the SET button while displaying the image signal, The area corresponding to the pointer can be selected.

  The power control unit 80 includes a battery detection circuit, a DC-DC converter, a switch circuit for switching a block to be energized, and the like, and detects whether or not a battery is mounted, the type of the battery, and the remaining battery level. Further, the power control unit 80 controls the DC-DC converter based on the detection result and the instruction of the system control unit 50, and supplies a necessary voltage to each unit including the recording medium 200 for a necessary period. The power supply unit 30 includes a primary battery such as an alkaline battery and a lithium battery, a secondary battery such as a NiCd battery, a NiMH battery, and a Li-ion battery, and an AC adapter.

  The recording medium I / F 18 is an interface with a recording medium 200 such as a memory card or a hard disk. The recording medium 200 is a recording medium such as a memory card for recording a captured image, and includes a semiconductor memory, a magnetic disk, and the like. In the present embodiment, the image signal output from the image processing unit 24 is recorded on the recording medium 200 in relation to the imaging operation performed in the photographing mode.

  In the present embodiment, a description will be given assuming that processing is realized by a circuit or processor corresponding to each block included in the digital video camera 100 as hardware. However, the embodiment of the present invention is not limited to this, and the processing of each block may be realized by a program that performs the same processing as that of each block.

《Presentation processing》
A presentation process performed by the digital video camera 100 according to the present embodiment having the above-described configuration to present information for facilitating the DR setting of an image signal obtained by imaging to a user will be described with reference to the flowchart of FIG. A specific process will be described. The processing corresponding to the flowchart can be realized by the system control unit 50 reading out a corresponding processing program stored in, for example, the non-volatile memory 56, developing the program in the memory 32, and executing the program. The present presentation process will be described as being started, for example, when an operation input related to an instruction to use the DR assist function is performed.

  In S301, the system control unit 50 specifies a corresponding DR (selected DR) based on the current exposure setting (selected exposure setting). The information of the selected DR may indicate, for example, a boundary value (maximum value, minimum value) of the brightness related to the DR and the number of corresponding STOPs. The information on the selected DR may be stored in advance for the selected exposure setting, or may be calculated by the system control unit 50 performing a predetermined calculation based on the selected exposure setting.

  In step S <b> 302, the system control unit 50 specifies the amount of change to the maximum DR related to the image signal that can be output by the digital video camera 100 (the number of steps per change / the number of STOPs). In the digital video camera 100 according to the present embodiment, in order to more accurately evaluate the brightness distribution of the subject, an image is captured with an exposure setting corresponding to the maximum DR that can be expressed in an image signal obtained by imaging the digital video camera 100. The obtained image signal is used. That is, when the subject has a brightness outside the range that can be represented by the selected DR, the brightness becomes a saturated value in the image signal represented by the selected DR and cannot be accurately evaluated. The evaluation is performed based on the image signal captured at the exposure setting corresponding to. In the present embodiment, a description will be given assuming that the maximum DR that can be supported by the digital video camera 100 is used as a DR having a wider range than the selected DR, but it is easily understood that the present invention is not limited to this. Let's do it. That is, the embodiment of the present invention only needs to present information based on an image signal that can be evaluated instead of at least a part of the brightness not included in the selected DR as a saturation value. Need not be the maximum DR if it has a wider range than the selected DR. Therefore, in the present presentation process, when using the DR assist function, the amount of change to a DR temporarily having a wider range than the selected DR (hereinafter referred to as “temporary DR”) is specified and obtained by the temporary exposure setting corresponding to the temporary DR. Subsequent processing is performed so that the brightness evaluation is performed on the image signal obtained.

Assuming that the change amount D _change to the temporary DR is D _now and the temporary DR (the maximum DR that can be set in the digital video camera 100) is D _max , the number of stages of the change amount to the temporary DR is as follows:
D _change = log ₂ (D _max / D _now )
Can be calculated as For example, when the maximum DR is 800% and the selected DR is 400%, the amount of change to the temporary DR is one step. When the selection DR is 300%, the change amount is about 1.52 steps.

  In S303, the system control unit 50 changes the exposure setting (changes to the temporary exposure setting) based on the change amount to the temporary DR calculated in S302. The change of the exposure setting may be performed by an existing method such as changing the aperture 101, the ND 104, the electronic shutter in the imaging unit 22, the state, value, and operation of the analog gain. For example, when the exposure setting is changed by the electronic shutter, if the shutter speed of the electronic shutter is 1/60 and the change amount is one step in the selected exposure setting, the system controller 50 sets the shutter speed of the electronic shutter to 1/60. Change to 120.

  In addition, the system control unit 50 also changes the gamma characteristic of the image signal obtained by imaging in the gamma correction process applied in the image processing unit 24. The gamma characteristic is a conversion characteristic when converting a signal level of an input signal (image signal) into a bit value of a corrected output signal. In general, the gamma characteristic assigns a signal level from a minimum value to a maximum value of DR expressed in an input signal to a bit value from the minimum value to the maximum value of the output signal. However, in the present presentation process, since the input signal is an image signal having a temporarily extended DR (temporary DR), the system control unit 50 determines that the image signal is the same as when the image signal is captured with the selected exposure setting. Change the gamma characteristic so that it becomes “visible”. That is, even if the image signal having the temporary DR is not included in the selected DR, the image signal having the temporary DR is not included in the selected DR so that the user can easily understand that the gradation is not expressed and the change of the exposure setting is preferable. The gamma characteristic is changed so that the image signal is converted into an image signal expressed by the brightness of the image.

It is assumed that a signal level (output level) Y output after gamma correction is Y with respect to a signal level (input signal level) X of an image signal obtained by capturing with the temporary exposure setting. In this case, normally, as shown by a solid line 401 in FIG. 4, the gamma is set so that the maximum value X _max of the input signal level corresponding to the maximum value of the temporary DR is assigned to the maximum value Y _max of the output signal level. Properties are determined. However, in the presentation processing of the present embodiment, as described above, the gamma characteristic is changed to a different characteristic in order to bring the “appearance” of the image signal closer to the image signal when the image is captured with the selected exposure setting. For example, as described above, when the selected DR is 400% and the temporary DR is 800%, the maximum value of the input signal level corresponding to the maximum value of the selected DR is:
(D _now / D _max ) · X _max = X _max / 2
Becomes That is, in the case of an image signal when the image is captured with the selected exposure setting, the signal level of X _max / 2 becomes the maximum value Y _max of the output signal level.
The system control unit 50 sets the gamma characteristic of the conversion characteristic indicated by the following in the image processing unit 24. Here, γ _assist (X) is a function (corresponding to the alternate long and short dash line 402) related to the gamma characteristic for converting the image signal having the temporary DR into an image signal expressed by the brightness included in the selected DR. Γ _normal (X) is a function (corresponding to the solid line 401) relating to gamma correction normally performed on an image signal having a temporary DR, and indicates X = X _max and Y = Y _max .

  In the present embodiment, a description will be given assuming that such a change in the gamma characteristic is performed in order to unify the “appearance” of the image signal before and after using the DR assist function. However, in the temporary DR, in order to make it easy to determine the area in which the brightness is expressed, the image signal obtained by performing the gamma correction process using the normally used gamma characteristic on the image signal captured in the temporary exposure setting is obtained. The gamma characteristic need not be changed so that the image is displayed.

  In step S304, the system control unit 50 controls each block to perform imaging with the changed exposure setting in step S303, that is, the temporary exposure setting, and causes the imaging unit 22 to output an image signal. That is, in the digital video camera 100 according to the present embodiment, while the DR assist function is used, an image obtained by imaging with the temporary exposure setting is used instead of the exposure setting (selection exposure setting) before the use of the function is started. The following various processes are performed based on the signal.

  In step S305, based on the image signal before the gamma correction process is applied, the image processing unit 24 acquires a photometric value indicating the brightness of the predetermined region in the image signal, for the region. The predetermined area is divided into, for example, an 8 × 8 frame (photometry frame) as shown in FIG. 5B with respect to an image signal obtained by imaging with the temporary exposure setting shown in FIG. May be an area selected by the user from an area defined in advance, or a predetermined area. The image processing unit 24 obtains an average luminance value of an image signal in a predetermined area and stores the average luminance value in the memory 32 via the memory control unit 15 as a photometric value of the area. In the present embodiment, an explanation is given assuming that an average luminance value in a region is used as a photometric value indicating the brightness of a predetermined region. However, the present invention is not limited to this. As the value indicating the brightness of the predetermined area, any value may be used as long as it is a value that serves as an index of the brightness, such as an integrated value of the brightness value in the area or an EV value. Further, in the present embodiment, a description will be given assuming that the photometric value of one area selected by the pointer is acquired in this step, but the present invention is not limited to this, and photometric values of one or more predetermined areas are acquired. Needless to say, it may be something.

  In step S306, the image processing unit 24 applies a gamma correction process to the image signal obtained by the temporary exposure setting, converts the image signal into a display image signal to be displayed on the display unit 28, and displays the converted display image signal. The signal is stored in the memory 32 via the memory control unit 15. As described above, the gamma correction process performed in this step is performed using the gamma characteristic changed in S303, and the display image signal is not a temporary DR but a brightness included in the selected DR. The image signal is represented.

  In step S307, the image processing unit 24 uses the display unit 28 to present information for facilitating DR setting of the image signal obtained by imaging to the user. Specifically, the image processing unit 24 includes a temporary DR 602, a selected DR 603, a pointer 604, and an area (a predetermined area) indicated by the pointer 604 in addition to the display image 601 based on the display image signal as shown in FIG. A screen in which the photometric values 605 of the (area) are arranged is generated. The temporary DR 602, the selected DR 603, and the photometric value 605 are arranged on a uniform scale using a scale that indicates the brightness (the number of STOPs) included in the temporary DR so that comparison is easy. In the example of FIG. 6, a temporary DR 602, a selected DR 603, and a photometric value 605 are arranged in an area different from the area where the display image 601 is presented, as information for facilitating DR setting for the user. However, information presentation is not limited to this, and may be performed, for example, by superimposing on the display image 601. After the processing of S307 is completed, the system control unit 50 returns the processing to S304. By doing so, by the present presentation process, while the DR assist function is used, information for facilitating the DR setting for the user can be presented to the user together with the through image.

  In the presentation processing of the present embodiment, the boundary value (maximum value, minimum value) of the selected DR 603 and the photometric value 605 of a predetermined area are described on the scale related to the temporary DR 602, but the present invention is not limited to this. The implementation is not limited to this. For example, in the case of a high-luminance area, if it is possible to determine whether or not the photometric value of the area is included in the selected DR and how much the photometric value deviates from the maximum value of the selected DR, the user can determine the desired floor. It is possible to grasp the exposure setting at which the tonal expression is made. Therefore, in the embodiment of the present invention, not only the display mode as shown in FIG. 6 but also information indicating quantitatively the difference between the value indicating the brightness of the predetermined area and the maximum value of the selected DR is presented. If this is the case, it is possible to allow the user to make a suitable DR setting. In the present embodiment, the photometric value and the maximum value of the selected DR are presented so as to be comparable in order to mainly ensure the gradation expression in the high-luminance area. However, the present invention is not limited to this. It is easy to understand that it is not limited. That is, the present invention can be applied to avoid blackout in a low-luminance area, and whether or not the photometric value is included in the selected DR is displayed so that the photometric value and the minimum value of the selected DR can be compared. May be presented. Of course, whether or not the selected DR is included does not need to be a comparison between the photometric value and either the maximum value or the minimum value of the selected DR, and the comparison between both the maximum value and the minimum value of the selected DR and the photometric value. It may be done by presenting the result.

  As described above, according to the presentation processing of the present embodiment, even if a subject having a brightness that is not included in the DR corresponding to the currently set exposure setting is included in the imaging range, the subject is preferably It is possible to present information that enables a user to make a proper DR setting.

[Embodiment 2]
In the first embodiment described above, the mode in which the user can determine whether or not the photometric value at the specified position (predetermined area) is included in the selection DR has been described. That is, in the mode of the first embodiment, the user selects an area in which the desired gradation expression is not likely to be performed, so that it is determined whether or not the photometry value is included in the selected DR for the area. Even if there are other areas that show higher photometric values, they may be overlooked by the user. In the present embodiment, a description will be given of an information presentation mode that allows a user to more easily understand whether or not the brightness distribution of a subject present in an imaging range is included in a selected DR when the DR assist function is used. Note that the configuration of the digital video camera 100 of the present embodiment is the same as that of the digital video camera 100 of the first embodiment, and a description thereof will be omitted.

《Presentation processing》
Hereinafter, a specific process of the presentation process executed in the digital video camera 100 of the present embodiment will be described with reference to the flowchart of FIG. The processing corresponding to the flowchart can be realized by the system control unit 50 reading out a corresponding processing program stored in, for example, the non-volatile memory 56, developing the program in the memory 32, and executing the program. Similar to the first embodiment, the present presentation process will be described as being started, for example, when an operation input related to an instruction to use the DR assist function is performed. In the presentation processing of the present embodiment, steps for performing the same processing as in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Hereinafter, steps for performing processing characteristic of the present embodiment will be described. .

  After the image signal captured with the temporary exposure setting is obtained in S304, the image processing unit 24 obtains a photometric value for each pixel group included in the image signal in S701. Then, the image processing unit 24 generates photometric value distribution information used for generating a histogram (frequency map) in which the number of pixels having the corresponding photometric value is counted for each predetermined value range indicated by the scale relating to the temporary DR. Is stored in the memory 32 via the memory control unit 15. The processing performed in this step corresponds to performing the processing executed in S305 of the presentation processing of the first embodiment on a plurality of areas by changing a predetermined area to a pixel size. In the present embodiment, a description will be given assuming that a photometric value is acquired for each pixel and distribution information of the photometric value is generated. However, in the embodiment of the present invention, the unit for acquiring the photometric value need not be limited to this, and the entire image signal is divided into regions having an arbitrary size and shape, and the image signal is generated with reduced resolution. Needless to say, it may be.

  After the conversion into the display image signal in S306, the image processing unit 24 uses the display unit 28 in S702 to present information for facilitating the DR setting of the image signal obtained by imaging to the user. Do. As shown in FIG. 8A, the information presentation in the present embodiment is based on the presentation mode of the first embodiment, and there is no pointer 604 and the photometric value 605 of the corresponding area of the pointer 604, and the image is displayed based on the photometric value distribution information. The difference is that the histogram 801 generated by the processing unit 24 is included. By doing so, it is possible to present information capable of comparing the distribution of the photometric value related to the subject with the selected DR, and as a result, it is possible for the user to make a suitable DR setting that covers the distribution. be able to.

[Modification 1]
In the above-described second embodiment, it has been described that the histogram relating to the brightness distribution of the subject is presented, so that the user is presented with whether or not the selected DR includes the distribution. However, there is a possibility that the user does not necessarily want to perform all the gradation expressions in the captured image signal. That is, even with the selected exposure setting corresponding to the selected DR, if the brightness distribution of the subject is covered to some extent in the obtained image signal, it is determined that the user does not need to change the exposure setting. May be done.

  Therefore, in addition to or in place of the histogram, the image processing unit 24 presents the number of pixels including the photometric value in the selected DR and the ratio of the pixel to the total number of pixels based on the photometric value distribution information. The screen may be configured to perform the operation. Alternatively, on the contrary, the image processing unit 24 may configure the screen to present the number and the ratio of the pixels whose brightness is not included in the selected DR. FIG. 8B is an example of a screen configuration in which, in addition to the histogram, the ratio 802 of the pixels included in the selected DR among the pixel groups included in the image signal obtained by capturing the image with the temporary exposure setting is indicated by a numerical value. . By doing so, it is possible to present information that enables the user to make a suitable DR setting, including not changing the exposure setting.

[Modification 2]
By the way, when the DR is extended, the reduction in the amount of light caused by setting the exposure to under (decreasing the amount of exposure) is used to apply gamma correction to ensure uniform subject brightness in the output signal regardless of the DR. I am trying to do it. That is, the gamma correction performed when the DR is extended is equivalent to increasing the amplification factor (gain) of the signal level, and as a result, image quality deterioration due to a decrease in the S / N ratio of the output signal can be led. In other words, in order to reduce the image quality degradation while ensuring the desired gradation expression, it is desirable to select a DR that indicates the narrowest possible range from the DRs including the brightness range of the desired subject.

  Therefore, when presenting information for facilitating the DR setting to the user, the image processing unit 24 further indicates the boundary values (maximum value and minimum value) of each of the DRs that the digital video camera 100 can support. It may be. By doing so, even if there are exposure settings corresponding to a plurality of types of DRs, the user includes the distribution according to the distribution of the brightness of the subject, and further sets the amplification factor of the signal level. Exposure settings that can be minimized can be easily understood. At this time, a dynamic range satisfying a predetermined condition, such as a dynamic range capable of minimizing the amplification factor of the signal level, is displayed so as to be selectable, and when there is an operation input related to the selection, the system control unit 50. May be configured to change to the corresponding exposure setting.

[Other Embodiments]
The present invention supplies a program for realizing one or more functions of the above-described embodiments to a system or an apparatus via a network or a storage medium, and one or more processors in a computer of the system or the apparatus read and execute the program. This processing can be realized. Further, it can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

  15: memory control unit, 22: imaging unit, 24: image processing unit, 32: memory, 56: nonvolatile memory, 50: system control unit, 100: digital video camera

Claims (16)

Selecting means for selecting one exposure setting from among a plurality of exposure settings each corresponding to a different dynamic range;
Based on an image signal obtained by imaging with an exposure setting corresponding to a second dynamic range having a wider range than the first dynamic range corresponding to the exposure setting selected by the selection unit, the predetermined image signal is determined. Acquisition means for acquiring the brightness of the area of
When the brightness of the predetermined region obtained by the obtaining unit is not included in the first dynamic range, a presenting unit that presents information for recognizing the user to that effect ;
An image processing apparatus comprising: 2. The image processing apparatus according to claim 1, wherein the presenting unit presents information indicating how far the brightness of the predetermined area is separated from a boundary value of the first dynamic range. It said presenting means, the image processing apparatus according to claim 1 or 2, characterized in that presents information indicating a boundary value of the predetermined dynamic range the information indicating the brightness first region. The presenting means presents, on a scale indicating the second dynamic range, information indicating a brightness value of the predetermined area and information indicating a boundary value of the first dynamic range. The image processing apparatus according to claim 1 . Said presenting means, the dynamic range corresponding to each of the plurality of exposure settings, according to any one of claims 1 to 4, characterized in that further to present information indicating the boundary values of the dynamic range Image processing device. The said presenting means further presents a selectable dynamic range that includes the brightness of the predetermined area and that satisfies a predetermined condition among the dynamic ranges corresponding to each of the plurality of exposure settings. Item 6. The image processing apparatus according to any one of Items 1 to 5 . Said presenting means, to claim 1, characterized in that presenting a front SL information indicating predetermined information indicating the brightness distribution of a pixel group included in the region between the first boundary value dynamic range 7. The image processing device according to any one of 6 . Said presenting means, among pre-Symbol pixel group included in a predetermined region, including free ratio of pixels is, and the brightness value is the first dynamic range with brightness values of the first dynamic range The image processing apparatus according to any one of claims 1 to 7 , wherein information indicating at least one of the ratios of pixels that are not present is presented. Said presenting means, the information to recognize the user of the fact, any of claims 1 to 8, characterized in that the presentation by displaying the Viewing apparatus to the image together with based on the image signal 2. The image processing device according to claim 1. A conversion unit configured to convert the image signal into an image signal represented by the first dynamic range;
Said presenting means, the image of claim 9, wherein the information to recognize the user of the fact, and displaying before Symbol display the image together with based on the image signal converted by said converting means Processing equipment. The second dynamic range, according to any one of claims 1 to 10, characterized in that a dynamic range including the maximum brightness of the dynamic range corresponding to the plurality of exposure set in the range Image processing device. The second dynamic range, image processing apparatus according to any one of claims 1 to 11, characterized in that a dynamic range having a maximum in the range in the image pickup device for capturing the image signal. Imaging means;
An image processing apparatus according to any one of claims 1 to 1 2,
An imaging device comprising: A selection step of selecting one exposure setting from a plurality of exposure settings each corresponding to a different dynamic range;
Based on an image signal obtained by imaging with an exposure setting corresponding to a second dynamic range having a range wider than the first dynamic range corresponding to the exposure setting selected in the selection step, a predetermined value of the image signal is determined. An obtaining step of obtaining the brightness of the area of
When the brightness of the predetermined area acquired in the acquiring step is not included in the first dynamic range, a presentation step of presenting information for causing the user to recognize the fact ;
A method for controlling an image processing apparatus, comprising: A selection step of selecting one exposure setting from a plurality of exposure settings each corresponding to a different dynamic range;
An imaging step of imaging with an exposure setting corresponding to a second dynamic range having a wider range than the first dynamic range corresponding to the exposure setting selected in the selection step and outputting an image signal;
An acquisition step of acquiring brightness of a predetermined area of the image signal based on the image signal output in the imaging step;
When the brightness of the predetermined area acquired in the acquiring step is not included in the first dynamic range, a presentation step of presenting information for causing the user to recognize the fact ;
A method for controlling an imaging device, comprising: A program for a computer to function as each means of the image processing apparatus according to any one of claims 1 to 1 2.