JP2017126958A - Image processing unit, imaging apparatus, control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To present an index of brightness of a subject that enables a proper dynamic range to be set.SOLUTION: An image processing unit selects one exposure setting out of a plurality of exposure settings, measures brightness of a predetermined subject based upon an image signal generated by imaging with the selected exposure setting, and presents information associated with the brightness of the predetermined subject. The unit performs control to change the exposure setting to be selected to an exposure setting for imaging of an image signal in a dynamic range in which brightness of the predetermined subject of the measurement result is based upon the measurement result. The plurality of exposure settings include a first kind of exposure setting predetermined such that imaging of an image signal for recording is performed and a second kind of exposure setting predetermined such that the imaging of the image signal for recording is not performed.SELECTED DRAWING: Figure 3

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. Patent Document 1 discloses that the distribution of minimum and maximum luminance levels is measured, and the camera state is controlled so that a wider DR image can be obtained in which the range of luminance levels determined based on the distribution falls. ing. 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.

JP 2000-278600 A

  However, in the method described in Patent Document 1, since the minimum luminance level and the maximum luminance level are measured from the imaging signal output by imaging, the measurable luminance level is limited to the maximum DR provided for imaging. Is done. That is, even if a subject having a luminance exceeding the DR is included, the luminance of the subject is saturated in the imaging signal, and thus cannot be measured, and an image in which the DR is suitably extended cannot always be generated. .

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an image processing apparatus, an imaging apparatus, a control method, and a program for presenting a brightness indicator of a subject, which enables setting of a suitable dynamic range. And

  In order to achieve the above-described object, an image processing apparatus according to the present invention includes a selection unit that selects one exposure setting from among a plurality of exposure settings, and an image signal that is captured with the exposure setting selected by the selection unit. Based on the measurement means for measuring information on the brightness of the predetermined subject, a presentation means for presenting the brightness of the predetermined subject, and the selection of the exposure setting by the selection means based on the measurement result by the measurement means Control means, and the control means causes the selection means to select an exposure setting for capturing an image signal having a dynamic range in which the brightness of a predetermined subject in the measurement result falls, and the plurality of exposure settings are images for recording. Including a first type of exposure setting that is predetermined for performing signal imaging, and a second type of exposure setting that is predetermined for not capturing an image signal for recording. It is characterized in.

  With such a configuration, according to the present invention, it is possible to present an index of the brightness of a subject that makes it possible 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. Screen configuration example of information presentation according to the first modification of the present invention The figure for demonstrating the gamma characteristic which produces | generates the image signal for a display in DR measurement mode based on the modification 1 of this invention. Screen configuration example of information presentation according to the second modification 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 an index 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 Accordingly, the digital video camera 100 according to the present embodiment includes not only a recording use but also a brightness distribution of a subject and this in addition to a recording mode for recording a captured image output from the imaging unit 22 as a settable mode. It has a DR measurement mode for measuring DR. In the DR measurement mode, the user can easily determine the imaging setting / exposure setting (or DR setting) for obtaining a desired imaging result, or can inform the user of the brightness indicator of the subject. Is presented.

  In the DR measurement mode, in order to present the information to the user, the image processing unit 24 includes the information as superimposed data in the display image signal. 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 these information 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 the display unit 28. It is not limited to. For example, the presentation of information does not need to be performed by a GUI as described later, but may be performed by presenting a necessary numerical value. 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.

  In order to enable suitable information presentation, the plurality of exposure settings are a first type exposure setting that is determined in advance in consideration of the image quality of the captured image and the like, and is used for recording the captured image. And a second type of exposure setting that is not used for image recording. In the shooting mode, only the first type exposure setting is used, but in the DR measurement mode, the first type exposure setting and the second type exposure setting are used. This is because the brightness of the subject does not fit in the DR that can be handled with the first type of exposure setting (the maximum brightness exceeds the maximum value of DR that can be handled, the minimum brightness of the DR that can handle the minimum brightness) It is assumed that the value is below the value. That is, in the first type of exposure setting, the subject that causes overexposure cannot be measured accurately, but the digital video camera 100 of the present embodiment can perform this DR measurement. The use of the second type of exposure setting is allowed only in the mode. While the second type of exposure setting is based on the premise that the output of an imaging signal with a suitable image quality is not guaranteed and is not recorded, it is basically more extended than the exposure setting of the first type. Enables imaging in DR. Therefore, the DR measurement mode can obtain a captured image related to a wider DR than the imaging mode, reduces the possibility of measurement being impossible due to the saturation value, and presents a more accurate index of the brightness of the subject to the user. Can do.

  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 changeover 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 (shooting mode), a measurement mode, a reproduction mode, and the like. The modes included in the shooting mode include the above-described normal mode and high brightness priority mode. 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 a brightness index of a subject that enables a suitable dynamic range to be set, which is executed by the digital video camera 100 of the present embodiment having the above-described configuration, will be described with reference to the flowchart of FIG. A typical 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 it in the memory 32, and executing it. This presenting process will be described as being started when an operation input for setting the mode of the digital video camera 100 to the DR measurement mode is made via the mode changeover switch 60, for example. In the following description, the brightness value which is the signal level of the brightness component of the image pickup signal is used as the value for evaluating the brightness of the subject. However, the brightness evaluation value may be other values such as an EV value. It goes without saying that values of types may be used.

  In S301, the image processing unit 24 specifies a signal level indicating the maximum brightness for the image signal (imaging signal) obtained by imaging. Specifically, the image processing unit 24 acquires an imaging signal, converts the imaging signal into a luminance signal, and specifies a maximum luminance value. The luminance signal is obtained by performing a predetermined conversion calculation based on the signal level of each color component of the acquired imaging signal. In order to measure the luminance of the subject, the luminance signal is generated based on the image signal before the gamma correction processing or the like is applied.

  In S302, the image processing unit 24 sets the DR (selected DR) corresponding to the current exposure setting (selected exposure setting), which is the exposure setting set in the shooting mode before the DR measurement mode is set, to S301. It is determined whether or not the maximum luminance value specified in step 1 is included. The information on the selection DR may be determined in advance as described above and stored in the memory 32, for example, and the image processing unit 24 determines this step by referring to the information. The determination in this step is to determine whether or not a pixel signal whose luminance is saturated is included in the imaging signal, that is, whether or not there is a subject whose gradation is lost in the imaging by the selective exposure setting. is there. If the image processing unit 24 determines that the specified maximum luminance value is included in the selected DR, it moves the process to S303, and if it determines that it is not included, moves the process to S305. In the present embodiment, the description will be made assuming that the selected exposure setting is one of the first type exposure settings so that the change of the presentation mode can be easily grasped.

  In S303, the image processing unit 24 specifies a range of luminance values (luminance range) of the imaged subject based on the luminance signal related to the imaging signal. In the presentation process of the present embodiment, the brightness range defined by the maximum value and the minimum value of the brightness value indicated by the brightness signal related to the imaging signal will be described as an index of the brightness of the subject. Implementation need not be limited to this. For example, the brightness indicator of the subject may indicate only the maximum value of the luminance value, only the minimum value, or a pixel distribution related to the luminance.

  In S304, the image processing unit 24 generates a notification image that shows the selected DR and the luminance range information of the subject obtained in S303 in a manner that can be compared, displays the notification image on the display unit 28, and presents it to the user. The notification image may indicate the luminance range of the subject and the selection DR on a scale indicating the luminance value included in the selection DR, for example, so that the user can indicate that the selection DR covers the luminance range of the subject. I can grasp it.

On the other hand, when it is determined in S302 that the maximum luminance value is not included in the selection DR, the system control unit 50 changes the exposure setting in S305. The change of the exposure setting in this step relates to the maximum DR that can be handled by the exposure setting of the first type (DR including the maximum brightness or DR including the maximum brightness range: maximum DR for recording). This is a change to the exposure setting (maximum exposure setting for recording). That is, the system control unit 50 changes the exposure setting to the maximum DR among the exposure settings that can be used in the shooting mode (a mode in which the imaging signal can be recorded). Here, the exposure setting change stage number D _change related to the recording maximum DR is set so that the selected DR is D _now (unit%) and the recording maximum DR is D _max (unit%).
D _change = log ₂ (D _max / D _now )
Can be calculated as For example, when the selected DR is D _now = 400% and the DR after changing the exposure setting is D _change = 800%, the number of change steps is one. When the selected DR is 300%, the number of change stages is about 1.52. The system control unit 50 changes the exposure setting based on the calculated number of change steps. For example, when the exposure setting is changed by adjusting the shutter speed of the electronic shutter, if the selective exposure setting is 1/60, the change step number of 1 corresponds to changing it to 1/120. The exposure setting changing method 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, or operation of the analog gain.

  In S <b> 306, the image processing unit 24 specifies a signal level indicating the maximum brightness for the imaging signal newly obtained by imaging with the changed exposure setting (maximum recording exposure setting). Similar to S301, the image processing unit 24 converts the imaging signal into a luminance signal and specifies the maximum luminance value.

  In S307, the image processing unit 24 determines whether or not the maximum luminance value specified in S306 is included in the DR (maximum recording DR) corresponding to the recording maximum exposure setting. If the image processing unit 24 determines that the specified maximum luminance value is included in the maximum recording DR, the image processing unit 24 shifts the processing to S308, and determines that it is not included, shifts the processing to S310.

  In S308, the image processing unit 24 specifies the luminance range of the imaged subject based on the luminance signal related to the imaging signal. The luminance range specified in this step indicates a range different from the luminance range specified in S303 because the exposure setting in which the image is taken is different even for the same subject.

  In S309, the image processing unit 24 generates a notification image that can be compared with the recording maximum DR and information on the luminance range of the subject obtained in S308, displays the notification image on the display unit 28, and presents it to the user. . For example, the notification image may indicate the luminance range of the subject, the selection DR, and the maximum recording DR on a scale indicating the luminance value included in the maximum recording DR. By such presentation, the user can grasp that the luminance range of the subject is not covered by the selected DR, but the luminance range of the subject is covered by the maximum recording DR. In addition, it is possible to grasp how much the exposure setting that extends the DR from the selected exposure setting.

  On the other hand, if it is determined in S307 that the maximum luminance value is not included in the maximum recording DR, the system control unit 50 changes the exposure setting in S310. The exposure setting change in this step is a change to the second type exposure setting, that is, a change to the exposure setting used only in the DR measurement mode. As described above, the exposure type of the second type does not consider the image quality in the imaging signal, and is an exposure setting provided for the purpose of measuring the brightness, and measuring the luminance value exceeding the maximum recording DR. Is possible. The process of this step is repeatedly executed until the luminance value of the subject is included in the corresponding DR. For example, after the change to the exposure setting related to the DR having the next highest maximum value for the recording maximum DR, It is changed to the exposure setting related to DR in which the maximum luminance value is sequentially increased every time it is executed. That is, the system control unit 50 sequentially selects exposure settings included in the second type of exposure setting in the repeated execution of this step so as to sequentially include higher luminance values in the DR.

  In S <b> 311, the image processing unit 24 identifies a signal level indicating the maximum brightness for the imaging signal obtained by imaging with the changed exposure setting (measurement exposure setting). Similar to S301 and S306, the image processing unit 24 converts the imaging signal into a luminance signal and specifies the maximum luminance value.

  In S312, the image processing unit 24 determines whether or not the DR corresponding to the measurement exposure setting (measurement DR) includes the maximum luminance value specified in S311. If the image processing unit 24 determines that the specified maximum luminance value is included in the measurement DR, it moves the process to S313, and if it determines that it is not included, returns the process to S310. That is, when the imaging signal has a saturation signal, the gradation of the subject corresponding to the saturation signal is lost, and the brightness of the subject cannot be evaluated favorably. The processes of S310 to S312 are repeated until a signal is obtained.

  In step S313, the image processing unit 24 specifies the luminance range of the imaged subject based on the luminance signal related to the imaging signal. The luminance range specified in this step is a value obtained by suitably evaluating the maximum luminance value that is not included in the maximum recording DR.

  In S314, the image processing unit 24 generates a notification image that can be compared with the measurement DR and the information on the luminance range of the subject obtained in S313, displays the notification image on the display unit 28, and presents it to the user. For example, the notification image may indicate the luminance range of the subject, the selection DR, the maximum recording DR, and the measurement DR on a scale indicating the luminance value included in the measurement DR. With such presentation, the user cannot perform shooting (image recording) that covers the luminance range of the subject, but can grasp how much the luminance range of the subject is. In addition, it is possible to grasp how much the shooting conditions can be changed to perform shooting while ensuring gradation expression in a high-luminance subject.

  As described above, according to the image processing apparatus of the present embodiment, it is possible to present an index of the brightness of a subject that makes it possible to set a suitable dynamic range. The presentation process of the present embodiment can provide effective information even in the following scenes in which the exposure setting is adjusted, for example.

  For example, when shooting is performed by constructing a shooting environment using an illumination device or the like such as movie shooting, shooting is performed by using a luminance meter so that the luminance value of all subjects is included in the DR set in the digital video camera 100. It is common to build an environment. At this time, when the subject brightness is not included in the DR, it is necessary to construct a final photographing environment by adjusting the light amount, the irradiation angle, and the like of the illumination device. However, it is common to use a so-called incident luminance meter for measuring the light emitted to the subject, and it is necessary to perform measurement at a plurality of locations for each subject, and adjust the environment of the illumination device. This is repeated each time. In addition, the specifications of the target value and the like of the digital video camera 100 used and the luminance meter are often different. In order to match the measurement result of the luminance meter with the characteristics of the digital video camera 100 used, a setting corresponding to the measurement result is set. It is necessary to find out.

  On the other hand, it is also possible to measure the luminance value of the subject during imaging using an imaging device, and the setting can be performed without considering the characteristics of the luminance meter. As described above, the digital video camera 100 The measurement is limited to the DR range set in. For this reason, measurement was not possible when the DR was not included in the set DR and was saturated. That is, for a subject that causes saturation in the imaging signal, first, how much the light amount of the illumination device should be changed or how to change the DR of the digital video camera 100 in order to keep the luminance of the subject in DR. I couldn't figure out what to do at one time.

  Therefore, such adjustment work requires knowledge of the luminance meter and the digital video camera 100 and photographing experience, which may impose complicated work for users who are inexperienced at the introduction of equipment or who have little experience. On the other hand, according to the presentation processing of the present embodiment, even if there is a subject whose brightness exceeds DR that can be handled by the exposure setting of the first type prepared for shooting, Brightness can be evaluated and presented with exposure settings. Therefore, it is possible to make it easy for the user to set a suitable DR and adjust the lighting conditions.

[Modification 1]
In the presentation process of the above-described embodiment, the aspect in which the notification image is presented on the display unit 28 has been described. However, the presentation of information capable of comparing the luminance of the subject and various DRs is not limited to the presentation of the notification image alone. For example, the notification image (401) may be presented together with the image 402 related to the imaging signal as shown in FIG. Since the exposure setting is changed according to the maximum luminance value of the subject in the presentation process, an image in which the user cannot properly grasp the state of the subject such as the entire image 402 being dark depending on the luminance value can be presented. .

  In generating an image in which DR is extended, as described above, for example, it is necessary to change the gamma characteristic of gamma correction processing applied by a gamma correction circuit (not shown) included in the image processing unit 24. This corresponds to an image signal (output signal) for recording after application of various image processing including gamma correction processing, while the resolution of gradation expression in the image pickup signal (input signal) is changed by changing the exposure setting. Based on the fact that the resolution of the bit representation does not change. That is, since a plurality of image pickup signals obtained with exposure settings related to different DRs are expressed (compressed) in the same bit range in the output signal after gamma correction, the so-called “appearance” of the image changes. .

In this modification, the “appearance” of the image related to the imaging signal displayed with such a notification image is maintained regardless of the change in the exposure setting, when the DR is changed in the presentation process (S305, S311). The system control unit 50 changes the gamma characteristic set in the gamma correction circuit. The change of the gamma characteristic is based on the signal level obtained by multiplying the input signal level X after the DR change by D _now / D _max when the output signal level with respect to the input signal level X before the change of the DR (selected DR) is Y. The output signal level is set to Y. Here, D _now is the selected DR (unit%) corresponding to the selected exposure setting set in the shooting mode before the DR measurement mode is set, and D _change is the changed DR (maximum recording DR or measurement DR, unit%). The example shown in FIG. 5 shows the gamma characteristic set when the solid line 501 is D _now = 400%, and when the DR becomes D _change = 800% due to the change in the exposure setting, the alternate long and short dash line The gamma characteristic indicated by 502 is changed. That is, in such a DR change mode, D _now / D _max is ½, so the output signal level for the input signal level X before the DR change and the output signal for the input signal level X / 2 after the DR change. Gamma characteristics with the same level are set. That is, the luminance represented by the input signal level X _max before the DR change becomes the input signal level X _max / 2 after the DR change, and is converted to the output signal level Y _max as before the change. The input signal after the DR change may include pixels having a signal level _{equal to} or higher than X _max. However, in the gamma characteristic after the change, the input signal level higher than X _max / 2 is high-cut to the output signal level Y _max . Converted.

  In this way, the user confirms the distribution of the brightness of the subject and grasps the suitable DR setting while browsing the images with the same brightness expression before and after changing the exposure setting (before and after the DR change). can do.

[Modification 2]
In the embodiment described above, a notification image in a mode in which the maximum luminance value is specified and the exposure setting is changed on a pixel basis, and the luminance range of the subject can be compared with the selected DR on the DR scale including the luminance range of the subject. An example of presenting is described. However, the contrast between the luminance range of the subject and the selected DR does not have to be limited to this, and is, for example, made by presenting a value (difference value) corresponding to the change step number described in the embodiment. There may be.

  For example, as shown in FIG. 6, the difference value is presented for each region of a predetermined size determined for the image when the image related to the imaging signal is displayed on the display unit 28. Good. FIG. 6A shows an area provided so that the changed number of stages can be presented, and FIG. 6B shows a difference value of the area indicated by A in FIG. 6A and a frame indicating the area. The aspect shown with this is shown. The selection of the area may be performed based on, for example, a touch operation on the display unit 28 or an operation on the cross key.

In calculating the difference value Δ, the DR corresponding to the exposure setting set for measurement is D _measure (unit%), the maximum luminance value included in the DR is L _max , and the maximum luminance included in the selected region is calculated. If the luminance value is L _area , the following equation is used.
FIG. 6B shows an example in which D _now = 400%, D _measure = 800%, L _max = 4095, and L _area = 3500, and the difference value Δ is about 0.77. That is, if the DR is changed by at least 0.77 to obtain a DR of about 680%, the DR can contain the luminance of the subject in the selected area.

  In the presentation of the difference value Δ, for example, the difference value Δ or the display color of the frame is displayed depending on whether or not the maximum luminance value of the subject in the area falls within the maximum recording DR. Display control may be performed so that they are different. Alternatively, the digital video camera 100 leaves the subject in the area and the gradation representation by indicating the difference value up to the maximum DR that can record the image signal (the number of steps changed from the selected DR to the maximum recording DR) as a reference. The user can be informed whether or not recording is possible.

  In addition, although it has been described that the maximum luminance value in the region is used as the value indicating the brightness of the subject for the region, the embodiment of the present invention is not limited to this. For example, the luminance average value in the region and the representative value Any value may be used as long as the value can evaluate brightness.

[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 a 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 (11)

A selection means for selecting one exposure setting from a plurality of exposure settings;
Measurement means for measuring the brightness of a predetermined subject based on an image signal captured with the exposure setting selected by the selection means;
Presenting means for presenting information on the brightness of the predetermined subject;
Control means for controlling selection of exposure setting by the selection means based on the measurement result by the measurement means,
The control unit causes the selection unit to select an exposure setting for capturing an image signal having a dynamic range in which the brightness of the predetermined subject in the measurement result falls.
The plurality of exposure settings are a first type of exposure setting that is predetermined to capture an image signal for recording and a second that is predetermined to not capture an image signal for recording. An image processing apparatus comprising: a type of exposure setting.   The said presentation means presents the information regarding the brightness of the predetermined subject when the brightness of the predetermined subject in the measurement result is not a saturated signal level. Image processing device.   The control means sets an exposure setting for capturing an image signal having a wider dynamic range than the exposure setting related to the measurement result when the brightness of the predetermined subject in the measurement result is a saturated signal level. The image processing apparatus according to claim 1, further comprising a selection unit that selects the image processing apparatus. A setting unit that sets either a mode for capturing an image signal for recording or a mode for not capturing an image signal for recording;
The measurement by the measurement unit, the presentation by the presentation unit, and the control by the control unit are performed when the setting unit sets the mode in which the image signal for recording is not captured. Item 4. The image processing device according to any one of Items 1 to 3.   The presenting means is selected in the mode before the change when the setting is changed from the mode for capturing the image signal for recording by the setting means to the mode for not capturing the image signal for recording. 5. The image processing apparatus according to claim 4, wherein the dynamic range corresponding to the exposure setting that has been set is presented in a manner capable of comparing the brightness of the predetermined subject.   The image processing apparatus according to claim 5, wherein the presenting unit further presents an image related to an image signal captured with the exposure setting selected by the selecting unit. The image processing apparatus further includes conversion means for converting an image signal captured with the exposure setting selected by the selection means into an image having a dynamic range corresponding to the exposure setting selected in the mode before change,
The image processing apparatus according to claim 6, wherein the presenting unit presents the image converted by the converting unit together with information on the brightness of the predetermined subject.   The presenting means presents information indicating whether or not an exposure setting for capturing an image signal having a dynamic range in which the brightness of the predetermined subject falls within is the second type exposure setting. The image processing apparatus according to claim 1. Imaging means;
An image processing apparatus comprising: the image processing apparatus according to claim 1. A selection step of selecting one exposure setting from a plurality of exposure settings;
A measurement step of measuring the brightness of a predetermined subject based on the image signal captured with the exposure setting selected in the selection step;
A presentation step of presenting information on the brightness of the predetermined subject;
A control step for controlling selection of exposure setting in the selection step based on the measurement result in the measurement step
In the control step, an exposure setting for capturing an image signal of a dynamic range in which the brightness of the predetermined subject in the measurement result falls is controlled to be selected in the selection step,
The plurality of exposure settings are a first type of exposure setting that is predetermined to capture an image signal for recording and a second that is predetermined to not capture an image signal for recording. A control method for an image processing apparatus, comprising: a type of exposure setting.   The program for functioning a computer as each means of the image processing apparatus of any one of Claims 1 thru | or 8.