JP2017123575A - Image processing device, imaging device, control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a user to set a proper dynamic range.SOLUTION: An image processing device selects one exposure setting from plural exposure settings corresponding to respective different dynamic ranges. The device selects the brightness in a predetermined area of the image signal based on an image signal which is obtained by imaging with the exposure setting corresponding to a second dynamic range having a range wider than the first dynamic range corresponding to the selected exposure setting. Further, the device presents information representing whether the acquired brightness of the predetermined region is contained in the first dynamic range.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an image processing apparatus, an imaging apparatus, a control method, and a program, and more particularly, to a technique for performing imaging by changing a dynamic range and changing gradation expression.

  In an imaging apparatus such as a digital camera that performs imaging by exposing an imaging element, the charge accumulated in the photoelectric conversion element of the imaging element is saturated due to the brightness and exposure setting of the subject, for example, a high-luminance subject This can lead to a result of loss of gradation expression such as so-called whiteout in a region. On the other hand, in recent years, by using an image signal imaged with a low exposure amount, the dynamic range (DR) of the brightness distribution of the subject is precisely reproduced at the signal level while leaving the gradation expression in the high luminance region. Extended technology exists. Since the image signal obtained in this way has a low exposure amount and is generally dark, by applying gamma correction, the overall luminance is raised so as to ensure gradation expression in the high luminance region. Patent Document 1 discloses a gamma characteristic in which a low-to-medium luminance region in which a main subject exists is adjusted to have a luminance expression equivalent to that when DR is not expanded, 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 an output image signal having saturated pixels can be generated in an imaging device that performs imaging with imaging settings corresponding to the selected DR. For example, when imaging is performed with the imaging setting related to the DR selected by the user, the luminance (brightness, photometric value, etc.) of the subject existing in the imaging range may not be included in the selected DR. Naturally, the gradation expression related 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 check the image before shooting, for example, whether or not the gradation expression in the high luminance region is expressed in the DR. It was difficult to confirm visually.

  SUMMARY An advantage of some aspects of the invention is that it provides an image processing apparatus, an imaging apparatus, 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 of the present invention includes a selection unit that selects one exposure setting from a plurality of exposure settings corresponding to different dynamic ranges, and an exposure selected by the selection unit. Based on the image signal obtained by imaging with the exposure setting corresponding to the second dynamic range having a range wider than the first dynamic range corresponding to the setting, the brightness of a predetermined region of the image signal is acquired. It has an acquisition means, and a presentation means for presenting information indicating whether or not the brightness of the predetermined area acquired by the acquisition means is included in the first dynamic range.

  With such a configuration, according to the present invention, it is possible to allow the user to set a suitable dynamic range.

1 is an external view of a digital video camera 100 according to an embodiment of the present invention. 1 is a block diagram showing a functional configuration of a digital video camera 100 according to an embodiment of the present invention. The flowchart which illustrated the presentation processing performed with the digital video camera 100 which concerns on Embodiment 1 of this invention. The figure for demonstrating the gamma characteristic which produces | generates the image signal for a display in DR assist function based on embodiment of this invention. The figure for demonstrating the photometric value acquired according to Embodiment 1 of this invention Screen configuration example of information presentation according to Embodiment 1 of the present invention The flowchart which illustrated the presentation processing which concerns on Embodiment 2 of this invention Example of screen configuration for 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, which is a digital video camera capable of performing imaging using a plurality of exposure settings corresponding to different dynamic ranges (hereinafter referred to as 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 serve as 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, the display unit 28 is a display device provided to display image signals and various types of information that are shot and recorded in a plurality of shooting modes. Further, the digital video camera 100 is provided with a recording switch 61 for instructing photographing, a mode switching switch 60 for switching various modes, and a power switch 72 for switching power on / off. In addition, an operation member for receiving various operations from the user such as various buttons and cross keys is provided as the operation unit 70.

  The connector 112 is a connector for a connection cable when connecting the digital video camera 100 and an external device. The recording medium 200 is a detachably connected recording medium such as a memory card or a hard disk. When the recording medium 200 is stored in the recording medium slot 201, the recording medium 200 is connected to the digital video camera 100 and can transmit and receive information.

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

  The image processing unit 24 performs color conversion processing and gamma correction processing on the digital image signal (hereinafter simply referred to as image signal or image data) output from the A / D converter 23 or the image data acquired by the memory control unit 15. And processing such as addition of digital gain. Further, the image processing unit 24 performs predetermined calculation processing related to exposure control and 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 way, TTL (through the lens) AF (autofocus) processing, AE (automatic exposure) processing, AWB (auto white balance) processing, and the like are realized.

  The image processing unit 24 also generates an image signal (display image signal) to be displayed on the display unit 28 described later. The image signal for display is not limited to the image signal obtained by imaging (including those to which various processes are applied), and is further generated according to a predetermined condition or the state of the digital video camera 100. One or more GUIs may be superimposed on each other. In the digital video camera 100 according to the present embodiment, the image processing unit 24 uses, as an image signal for display, an image signal obtained by superimposing, for example, iris information, STOP information, and focus information at the time of imaging on the image signal obtained by imaging. 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 the user changes imaging settings (exposure settings) so that desired DR image signals are 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 changing 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 corresponding to different DRs. Here, the plurality of exposure settings need not all correspond to different DRs, and does not exclude the presence of a plurality of exposure settings corresponding to the same DR.

  By the way, whether or not the gradation desired by the user is expressed in the selected DR 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 visually check whether or not Therefore, the digital video camera 100 according to the present embodiment has a DR setting assist function for presenting information for facilitating the user to determine imaging setting / exposure setting (or DR setting) for obtaining a desired imaging result. Have. The DR setting assist function may be a function that can be additionally selected in a shooting mode in which various settings relating to imaging, such as a manual mode, can be changed.

  In the DR setting assist function, the image processing unit 24 includes the information as superimposed data in the image signal for display in order to present the user with information for facilitating the DR setting of the image signal obtained by imaging. Is realized. That is, in the digital video camera 100 of the present embodiment, the information is presented to the user through the display unit 28 together with the image signal obtained by imaging. However, in the implementation of the present invention, the presentation of information for facilitating the DR setting to the user does not have to be performed together with the 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 information does not have to be performed by a GUI as will be described later, but may be performed by simply presenting necessary numerical values. In addition, the information presentation is not limited to that performed in the display device including the display unit 28 provided in the digital video camera 100, but an external display device connected to the digital video camera 100 is used. Needless to say.

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

  As described above, various output signals generated by the image processing unit 24 are directly written in the memory 32 via the memory control unit 15. The memory 32 is a storage area for temporarily storing a digital image signal imaged by the imaging unit 22 and converted by the A / D converter 23. The memory 32 has a storage capacity sufficient to store a moving image and sound for a predetermined time. The memory 32 also serves as a storage device (video memory) for storing display image signals related 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 converted into an analog signal by 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 display a through image.

  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 for 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 included in the digital video camera 100. The system control unit 50 reads the operation program for each block recorded in, for example, the non-volatile memory 56, develops it in the system memory 52 and executes it, thereby controlling the operation of each block. The system memory 52 is a RAM or the like, for example, and functions not only as an operation program expansion area but also as a storage area for storing intermediate data 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 time measuring 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 time measuring function as necessary.

  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. As the modes included in the moving image recording mode and the still image recording mode, the above-described normal mode and high luminance priority mode are included. In addition to this, an auto shooting mode, an auto scene discrimination mode, a manual mode, various scene modes serving as shooting settings for each shooting scene, a program AE mode, a custom mode, and the like may be included. Information on the mode change made to the mode switch 60 is transmitted to the system control unit 50 as a predetermined control signal. The recording switch 61 accepts 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 reading a signal from the imaging unit 22 to writing moving image data to the recording medium 200 in response to reception of 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 selecting and operating various function icons displayed on the display unit 28, and receives operation inputs related to various functions. Various functions to which buttons are assigned may include, for example, end, return, image advance, jump, narrowing, attribute change, and the like. For example, when an operation input related to the menu button is performed, various settable menu screens are displayed on the display unit 28, and the assignment of operation inputs received for each operation member of the operation unit 70 is changed. Based on the menu screen displayed on the display unit 28, the user can make various settings intuitively by using the four-way cross key and the SET button. In the digital video camera 100 according to 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 the image signal is displayed, 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 that switches a block to be energized, and the like, and detects whether or not a battery is installed, the type of battery, and the remaining battery level. Further, the power control unit 80 controls the DC-DC converter based on the detection result and an instruction from 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 or a lithium battery, a secondary battery such as a NiCd battery, a NiMH battery, or a Li ion battery, an AC adapter, or the like.

  The recording medium I / F 18 is an interface with the 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, or the like. In the present embodiment, the image signal output from the image processing unit 24 is recorded on the recording medium 200 in connection with the imaging operation performed in the shooting mode.

  In the present embodiment, description will be made assuming that processing is realized by a circuit and a processor corresponding to each block included in the digital video camera 100 as hardware. However, the implementation 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 each block.

《Presentation processing》
A presentation process for presenting information for facilitating the user to perform DR setting of an image signal obtained by imaging, which is executed by the digital video camera 100 of the present embodiment having such a configuration, will be described with reference to the flowchart of FIG. Specific processing 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 it in the memory 32, and executing it. This presenting process will be described as being started when an operation input related to a DR assist function usage instruction is made, for example.

  In S301, the system control unit 50 identifies the corresponding DR (selected DR) based on the current exposure setting (selected exposure setting). The information on the selected DR may indicate, for example, the brightness boundary value (maximum value, minimum value) and the corresponding number of STOPs related to the DR. 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 identifies the maximum DR change amount (the number of stages related to the change / the number of STOPs) related to the image signal that can be output by the digital video camera 100. In the digital video camera 100 of the present embodiment, in order to more accurately evaluate the brightness distribution of the subject, imaging is performed with an exposure setting corresponding to the maximum DR that can be expressed in the image signal obtained by imaging of the digital video camera 100. The image signal is used. That is, when the subject has brightness outside the range that can be expressed by the selected DR, the brightness becomes a saturated value in the image signal expressed by the selected DR, and cannot be accurately evaluated. Therefore, the DR has a wider range. The evaluation is performed based on the image signal captured with the exposure setting corresponding to. In the present embodiment, it is assumed that the maximum DR that can be handled by the digital video camera 100 is used as a DR having a wider range than the selected DR. However, it is easily understood that the present invention is not limited to this. Let's be done. That is, the embodiment of the present invention is not limited as long as it presents information based on an image signal that can be evaluated instead of a saturation value that is not included in at least the selected DR, and is used for evaluation. If the DR has a wider range than the selected DR, it does not need to be the maximum DR. Therefore, in this presentation process, when using the DR assist function, a change amount to a DR having a wider range than the selected DR (hereinafter referred to as a temporary DR) is temporarily specified, and acquired by a temporary exposure setting corresponding to the temporary DR. Subsequent processing is performed so that the brightness evaluation is performed using the image signal.

The change amount D _change to the temporary DR is that the selected DR is D _now and the temporary DR (the maximum DR that can be set in the digital video camera 100) is D _max .
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 stage. When the selected DR is 300%, the amount of change is about 1.52.

  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 exposure setting may be changed by an existing method such as changing the aperture 101, the ND 104, the electronic shutter in the imaging unit 22, the state, value, or operation of the analog gain. For example, when changing the exposure setting with the electronic shutter, if the shutter speed of the electronic shutter is 1/60 and the amount of change is 1 in the selected exposure setting, the system control unit 50 sets the shutter speed of the electronic shutter to 1/60. Change to 120.

  The system control unit 50 also changes the gamma characteristic related to the gamma correction processing applied in the image processing unit 24 for the image signal obtained by imaging. The gamma characteristic is a conversion characteristic when the signal level of the input signal (image signal) is converted into the bit value of the corrected output signal. Usually, the gamma characteristic is to assign the signal level from the minimum value to the maximum value of DR expressed in the input signal to the bit value from the minimum value to the maximum value of the output signal. However, in this presentation process, the input signal becomes an image signal having a temporarily expanded DR (temporary DR). Therefore, the system control unit 50 is equivalent to the case where the image signal is captured with the selected exposure setting. Change the gamma characteristic so that it is “visible”. That is, even if an image signal having a temporary DR is included in the selected DR so that the user can easily understand that the gradation representation is not made in the image signal having the selected DR and the change of the exposure setting is preferable. The gamma characteristic is changed so that it is converted into an image signal expressed in brightness.

It is assumed that the signal level (output level) Y is output after gamma correction with respect to the signal level (input signal level) X of the image signal obtained by imaging with the temporary exposure setting. In this case, normally, as indicated 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. Characteristics are defined. However, in the presentation process according to the present embodiment, as described above, the “appearance” of the image signal is brought close to the image signal when the image is captured with the selected exposure setting, so that the gamma characteristic is changed to a different characteristic. 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
It becomes. That is, in the case of an image signal when the image is picked up 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 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 the image signal expressed by the brightness included in the selected DR. Γ _normal (X) is a function (corresponding to the solid line 401) related to gamma correction that is normally performed on an image signal having a temporary DR, and indicates Y = Y _max when X = X _max .

  In this embodiment, it is assumed that such a change in gamma characteristics is performed in order to unify the “appearance” of the image signal before and after using the DR assist function. However, in order to make it easy to discriminate the area where the brightness is expressed in the temporary DR, it is obtained by performing a gamma correction process using a normally used gamma characteristic on the image signal captured with the temporary exposure setting. It is not necessary to change the gamma characteristic so as to display an image.

  In step S304, the system control unit 50 controls each block to perform imaging with the exposure setting after the change 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 of the present embodiment, while using the DR assist function, an image obtained by imaging with the temporary exposure setting 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 S <b> 305, the image processing unit 24 acquires a photometric value indicating the brightness of a predetermined area in the image signal based on the image signal before the gamma correction process is applied. For example, the predetermined area is divided by an 8 × 8 frame (photometric frame) as shown in FIG. 5B with respect to an image signal obtained by imaging with the temporary exposure setting shown in FIG. 5A. May be a region selected by the user or a predetermined region. The image processing unit 24 acquires an average luminance value related to an image signal in a predetermined area, and stores it in the memory 32 via the memory control unit 15 as a photometric value of the area. In the present embodiment, it is assumed that the luminance average value in the area is used as the photometric value indicating the brightness of the predetermined area, but the embodiment of 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 serving as an index of brightness, such as an integral value or an EV value of luminance values in the area. In the present embodiment, a photometric value related to one area selected by the pointer is described as being acquired in this step. However, 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.

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

  In step S <b> 307, the image processing unit 24 uses the display unit 28 to present information for facilitating the user to perform DR setting of an image signal obtained by imaging. Specifically, the image processing unit 24, as shown in FIG. 6, in addition to the display image 601 based on the display image signal, the temporary DR 602, the selection DR 603, the pointer 604, and the area indicated by the pointer 604 (predetermined A screen on which the photometric values 605 of (region) are arranged is generated. The temporary DR 602, the selected DR 603, and the photometric value 605 are arranged in a uniform scale on a scale indicating the brightness (the number of STOPs) included in the temporary DR so that the comparison is easy. In the example of FIG. 6, a temporary DR 602, a selected DR 603, and a photometric value 605 are arranged as information for facilitating DR setting for the user in a region different from the region where the display image 601 is presented. However, the information presentation is not limited to this, and may be performed by superimposing the information on the display image 601, for example. After the process of S307 is completed, the system control unit 50 returns the process to S304. By doing in this way, this presentation process can present to the user information for making the DR setting easy for the user together with the through image while the DR assist function is used.

  Further, in the presentation process of the present embodiment, the boundary value (maximum value, minimum value) of the selected DR 603 and the photometric value 605 of a predetermined region have been described on the scale related to the temporary DR 602. Implementation is not limited to this. For example, for a high-luminance area, the user can 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. It is possible to grasp the exposure setting at which the key expression is made. Therefore, the embodiment of the present invention is not limited to the display mode as shown in FIG. 6. For example, information that quantitatively indicates the difference between the value indicating the brightness of the predetermined region and the maximum value of the selected DR can be presented. For example, a suitable DR setting can be made available to the user. In the present embodiment, the description has been made mainly on the assumption that the photometric value and the maximum value of the selected DR are presented in order to ensure the gradation expression of the high-luminance region. It will be readily understood that it is not limited. That is, the present invention is also applicable to avoid blackout in a low luminance region, 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. It may be presented. Of course, whether or not it is included in the selected DR 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 is a comparison between the photometric value and both the maximum value and the minimum value of the selected DR. It may be made by presenting the result.

  As described above, according to the presentation process of the present embodiment, even if a subject whose brightness is not included in the DR corresponding to the currently set exposure setting is included in the imaging range, it is preferable for the subject. It is possible to present information that makes it possible for the user to make a proper DR setting.

[Embodiment 2]
In the first embodiment described above, a mode has been described in which information that allows the user to determine whether or not a photometric value at a specified position (predetermined region) is included in the selection DR is presented. That is, in the aspect of the first embodiment, since the user selects a region where the desired gradation expression will not be made, it is determined whether or not the photometric value is included in the selection DR for the region. Even if there are other regions showing higher photometric values, they can be overlooked by the user. In the present embodiment, a description will be given of an information presenting mode that allows the user to understand whether or not the brightness distribution of the subject existing in the imaging range is included in the selected DR when using the DR assist function. 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, specific processing of the presentation processing 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 it in the memory 32, and executing it. As in the first embodiment, the present presentation process is described as being started when an operation input related to a usage instruction for the DR assist function is made, for example. In the presentation process of the present embodiment, the same reference numerals are assigned to the steps for performing the same processes as those of the first embodiment, and the description thereof will be omitted. The steps for performing the processes characteristic of the present embodiment will be described below. .

  After the image signal captured with the temporary exposure setting is acquired in S304, the image processing unit 24 acquires 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) that counts the number of pixels having the corresponding photometric value for each predetermined value range indicated by the scale related to the temporary DR. And stored in the memory 32 via the memory control unit 15. The process performed in this step corresponds to performing the process executed in S305 of the presentation process of the first embodiment for a plurality of areas by changing the predetermined area to the pixel size. In the present embodiment, it is assumed that photometric values are acquired in units of pixels to generate photometric value distribution information. However, the unit for acquiring the photometric value is not limited to this in the practice of the present invention, and the entire image signal is divided into regions having an arbitrary size and shape, and is generated with a 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 to present information for facilitating the user to perform DR setting of the image signal obtained by imaging in S702. Do. As shown in FIG. 8A, the information presentation in the present embodiment is an image based on the distribution information of the photometric value without the presentation mode of the first embodiment and the photometric value 605 of the pointer 604 and the corresponding area of the pointer 604. 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 and the selected DR, and as a result, it is possible for the user to perform a suitable DR setting that covers the distribution. be able to.

[Modification 1]
In the second embodiment described above, it has been described that a histogram related to the distribution of the brightness of the subject is presented to indicate to the user whether or not the distribution is included in the selection DR. However, the user may not always desire that all gradation representations be made in the captured image signal. That is, even if the selected exposure setting corresponds to the selected DR, if the brightness distribution of the subject is covered to some extent in the obtained image signal, the user determines that there is no need to change the exposure setting. There is also a possibility to do.

  Therefore, in addition to or instead 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 do so. Alternatively, on the contrary, the image processing unit 24 may configure the screen so as to present the number of pixels whose brightness is not included in the selection DR and the ratio thereof. FIG. 8B is a screen configuration example in which, in addition to the histogram, the ratio 802 of the pixels included in the selection DR among the pixel groups included in the image signal obtained by imaging with the temporary exposure setting is presented numerically. . By doing so, it is possible to present information that makes it possible for the user to make suitable DR settings, including not changing the exposure settings.

[Modification 2]
By the way, when extending DR, gamma correction is applied to reduce the amount of light due to underexposure (exposure amount is reduced), thereby ensuring uniform subject brightness regardless of DR in the output signal. Like to do. That is, the gamma correction performed when the DR is expanded is equivalent to increasing the amplification factor (gain) of the signal level, and as a result, image quality deterioration associated with a decrease in the S / N ratio in the output signal can be induced. In other words, in order to reduce image quality degradation while ensuring a desired gradation expression, it is desirable to select a DR that indicates a narrow range as much as possible from among the DRs including the brightness range of the desired subject.

  Therefore, the image processing unit 24 further indicates the boundary value (maximum value and minimum value) of each DR that the digital video camera 100 can handle in presenting information for making the DR setting easy for the user. It may be. In this way, even if there are exposure settings corresponding to a plurality of types of DR, the user can include the distribution in the range according to the brightness distribution of the subject, and further increase the amplification factor of the signal level. Easy to understand exposure settings that can be minimized. At this time, a dynamic range that satisfies a predetermined condition such as a dynamic range that can minimize the amplification factor of the signal level is displayed in a selectable manner, 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 that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  15: Memory control unit, 22: Imaging unit, 24: Image processing unit, 32: Memory, 56: Non-volatile memory, 50: System control unit, 100: Digital video camera

Claims (15)

A selection means for selecting one exposure setting from a plurality of exposure settings corresponding to different dynamic ranges;
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 means, a predetermined value of the image signal is determined. Acquisition means for acquiring the brightness of the area of
Presenting means for presenting information indicating whether or not the brightness of the predetermined area acquired by the acquiring means is included in the first dynamic range;
An image processing apparatus comprising:   The presenting means presents the brightness value of the predetermined area and at least one of the maximum value and the minimum value of the first dynamic range as information indicating whether or not they are included in the first dynamic range. The image processing apparatus according to claim 1, wherein:   The presenting means presents a brightness value of the predetermined region and a boundary value of the first dynamic range on a scale indicating the second dynamic range. Image processing apparatus.   The image processing apparatus according to claim 3, wherein the presenting unit further presents a boundary value of the dynamic range for the dynamic range corresponding to each of the plurality of exposure settings.   5. The presenting means further presents a dynamic range that includes a brightness of the predetermined area and satisfies a predetermined condition among the dynamic ranges of the plurality of exposure settings, so as to be selectable. An image processing apparatus according to 1.   The presenting means uses the brightness distribution of the pixel group included in the predetermined area and the brightness boundary value related to the first dynamic range as information indicating whether or not it is included in the first dynamic range. The image processing apparatus according to claim 1, wherein:   The presenting means, as information indicating whether or not it is included in the first dynamic range, out of the pixel group included in the predetermined region, the brightness value of the pixel included in the first dynamic range The image processing apparatus according to claim 1, wherein at least one of a ratio and a ratio of brightness that is not included in the first dynamic range is presented.   The said presentation means performs the said presentation by displaying the information which shows whether it is contained in the said 1st dynamic range with the image based on the said image signal on a display apparatus. The image processing apparatus according to any one of the above. Conversion means for converting the image signal into an image signal expressed in the first dynamic range;
The said presentation means displays the information which shows whether it is contained in a said 1st dynamic range with the image based on the image signal after the conversion by the said conversion means on the said display apparatus. Image processing apparatus.   The second dynamic range is a dynamic range including a maximum brightness in a dynamic range corresponding to the plurality of exposure settings. Image processing apparatus.   The image processing apparatus according to claim 1, wherein the second dynamic range is a dynamic range having a maximum range in an imaging apparatus that captures the image signal. Imaging means;
An image processing apparatus according to any one of claims 1 to 11,
An imaging device comprising: A selection step of selecting one exposure setting from a plurality of exposure settings corresponding to different dynamic ranges;
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 in the selection step, a predetermined value of the image signal is determined. An acquisition step of acquiring the brightness of the area of
A presentation step of presenting information indicating whether or not the brightness of the predetermined area acquired in the acquisition step is included in the first dynamic range;
A control method for an image processing apparatus, comprising: A selection step of selecting one exposure setting from a plurality of exposure settings corresponding to different dynamic ranges;
An imaging step of 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, and outputting an image signal;
An acquisition step of acquiring the brightness of a predetermined region of the image signal based on the image signal output in the imaging step;
A presentation step of presenting information indicating whether or not the brightness of the predetermined area acquired in the acquisition step is included in the first dynamic range;
A method for controlling an imaging apparatus, comprising:   The program for functioning a computer as each means of the image processing apparatus of any one of Claims 1 thru | or 11.