JP2005191985A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein it is difficult to estimate to what extent and to which direction an index (EV value) for exposure correction is to be changed from the distribution of a histogram when luminance data outputted from an imaging device is represented as the histogram as it is. <P>SOLUTION: This digital camera is provided with: a first histogram preparation means 9<SB>-1</SB>for preparing the histogram data of absolute luminance distribution corresponding to the luminance distribution of light which is inputted in a CCD 4 and photoelectrically converted in photographing or monitoring; and a display means 10 for displaying the histogram data of the absolute luminance distribution. In this way, the exposure correction is easily performed since absolute luminance corresponds to the EV value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a digital camera capable of displaying a luminance distribution during photographing or monitoring.

  A digital camera such as an electronic still camera is basically controlled so that a proper exposure is always obtained at the time of photographing by adjusting the aperture and the shutter, like a camera using a silver salt film. For this reason, it is common to have a function of automatic exposure control (program AE), but it is difficult to always obtain an appropriate exposure in any shooting environment, and there is a degree of freedom according to the photographer's preference. Since necessary, the exposure control switch can be switched between automatic and manual. Normally, a through image (monitor image) is displayed on the liquid crystal monitor when the power is turned on. At this time, if the result of automatic exposure control can be confirmed on the monitor screen before pressing the release switch for actually operating the shutter mechanism, it is easy to determine whether to switch automatically or manually, and it is possible to take a favorite image without failure.

For the purpose of meeting such demands, the luminance level is counted for each pixel based on the video signal from the solid-state imaging device, and a histogram indicating the luminance distribution is displayed on the liquid crystal monitor together with the monitor image, thereby taking an image. There is known a digital camera that can confirm whether or not the exposure of the monitor image is appropriate (see, for example, Patent Document 1).
In the digital camera described in Patent Document 1, the video signal from the solid-state image sensor is subjected to analog signal processing, AD conversion, and histogram data is generated from the luminance signal after digital signal processing. A graph indicating a luminance distribution is generated from, for example, data for one frame of the histogram data by a display circuit, and is displayed on the monitor image by the display device.

  Display data of such brightness is obtained from various analog signal processing, AD conversion processing, and tone conversion processing (gamma conversion) and resizing of the video signal output from the solid-state imaging device for gain adjustment and noise reduction. It is generated using a signal in the middle of being sent to a display monitor or recording medium through digital signal processing. Since the dynamic range of the solid-state imaging device, that is, the exposure allowable range (latitude) is narrower than that of the silver halide film, even if automatic exposure adjustment is performed, a subject outside the pattern of the program AE does not have proper exposure. In this case, due to overexposure or underexposure, details of highlight or shadow portions of the subject may not be reproduced, so-called white or black blur may occur.

  In order to confirm the result of the exposure adjustment on the monitor, the histogram display method described in Patent Document 1 displays the luminance level of the video signal from the solid-state imaging device as a bar graph or the like. By observing the luminance distribution shape using a bar graph on the liquid crystal display panel, the photographer can easily grasp the situation about the brightness of the screen of the captured image so that the appropriate exposure is obtained as necessary. In addition, manual brightness correction can be performed.

In manual brightness correction, the shutter speed and aperture are adjusted, but it is difficult to grasp how the exposure changes if these parameters are changed. Therefore, these parameters are integrated to display an EV value representing the exposure. There is a digital camera. In this case, the photographer adjusts the shutter speed and aperture using the EV value as an index.
However, since the histogram display described in Patent Document 1 is a display of the luminance level of the video signal, the histogram display does not directly correspond to the EV value. In particular, the luminance distribution shape by the histogram does not shift linearly with respect to the EV value adjustment amount due to the influence of gamma conversion, which is nonlinear conversion processing. For this reason, it is difficult to sensuously know how much the EV value is changed to obtain a desired luminance distribution, and there has been a disadvantage that it takes time for exposure correction.
Japanese Unexamined Patent Publication No. 7-38801

  The problem to be solved is that when the luminance data output from the image sensor is displayed as a histogram as it is, how much and in what direction the index (EV value) for exposure correction should be changed from the distribution. It is difficult to put on.

  The digital camera according to the present invention includes an imaging device, a histogram generation unit that generates histogram data of an absolute luminance distribution corresponding to the luminance distribution of light that is input to the imaging device and can be photoelectrically converted at the time of shooting or monitoring, and a histogram generation unit And a display means for displaying histogram data of the absolute luminance distribution generated in (1).

  The present invention preferably provides second histogram generation means for generating histogram data of relative luminance distribution based on an output signal of the image sensor, and selection means for selecting display of absolute luminance distribution and display of relative luminance distribution. The display means switches between the display of the absolute luminance distribution and the display of the relative luminance distribution according to the selection by the selection means.

In the present invention, preferably, the histogram generation means adds a difference obtained by subtracting an appropriate luminance level from a relative luminance of an output signal of the image sensor to an EV value set at the time of imaging or monitoring, and the absolute luminance Distribution histogram data is generated.
The present invention preferably further includes an EV value detecting means for detecting an EV value representing an exposure amount of the digital camera at the time of photographing or monitoring, and the display means displays the absolute luminance distribution on the display of the absolute luminance distribution. An index for the EV value is displayed.
Furthermore, the present invention preferably further comprises absolute luminance detecting means for detecting the absolute luminance of a specific area in the imaging screen at the time of shooting or monitoring from the histogram data of the absolute luminance distribution, and the display means includes the absolute luminance. An indicator corresponding to the distribution range of the EV value in the specific area is displayed on the distribution display.

  The present invention preferably further comprises mode selection means for selecting various modes by operation, and mode detection means for detecting the mode selected by the mode selection means, wherein the display means is exposure correction by the mode detection means. When it is detected that a mode has been selected, a histogram is displayed on the display unit together with a captured image or a monitor image, and the mode detection unit detects that a mode different from the exposure correction mode has been selected by the mode selection unit. In this case, the histogram in the display screen of the display means is hidden.

  Another digital camera according to the present invention includes a means for generating a histogram of luminance distribution, a display means for displaying the photographed image, a mode selection means for selecting various modes by operation, and a mode selected by the mode selection means. Mode detecting means for detecting the exposure, and when the mode detecting means detects that the exposure correction mode is selected, the histogram is displayed together with the photographed image on the display means, and exposure correction is performed by the mode detecting means. When the mode detection unit detects that a mode different from the mode is selected, the histogram in the display screen of the display unit is hidden.

The digital camera according to the present invention creates histogram data of an absolute luminance distribution corresponding to the luminance distribution of light that can be input to the image sensor and can be photoelectrically converted, and displays the absolute luminance based on the histogram data. There is an advantage that information on the brightness of the subject can be grasped more directly as compared with the case where the histogram data of the luminance distribution is created based on the received signal. In addition, when an EV value is used as an index for exposure correction, the luminance distribution changes linearly with respect to a change in the EV value. Therefore, it is necessary to determine how much the EV value needs to be raised or lowered next. There is an advantage that it can be easily grasped by operation.
In addition, the other digital camera according to the present invention has an advantage that the entire subject can be easily seen since the histogram in the display screen is set in an emergency when the exposure correction mode is switched to another mode.

FIG. 1 is a block diagram showing a schematic configuration of a digital camera according to an embodiment of the present invention. FIG. 2 is a diagram showing an arrangement of switches on the back and top surfaces of the digital camera and an electronic viewfinder as display means.
A digital camera 1 shown in FIG. 1 includes a lens 2, an aperture mechanism 3, a CCD 4 as an image sensor, an analog signal processing circuit 5 including a correlated double sampling (CDS) circuit and a variable gain amplifier, and an analog-digital conversion circuit (ADC). 6, an image memory 7 such as an SDRAM (Synchronous DRAM), an image processing unit 8, a first histogram generation unit 9 ₋₁ as a histogram generation unit, a second histogram generation unit 9 ₋₁ as a second histogram generation unit, a display It has a display unit 10 as a means, a recording medium 11 such as a flash memory, an exposure control mechanism 12 and a gradation conversion processing (gamma conversion) unit 13.

The exposure control mechanism 12 includes a motor driver 20 that controls opening and closing of the aperture mechanism, a timing generation circuit (TG) 21 that generates a pulse that defines the opening time of the electronic shutter of the CCD 4, that is, the shutter speed, an exposure control unit 22, an exposure calculation. Section 23 and exposure correction setting section 24. The exposure calculation unit 23 also functions as means for executing calculation at the time of generating a histogram of an absolute luminance distribution, which will be described later, in addition to performing calculation in the automatic exposure correction mode (program AE).
The exposure control unit 22, the exposure calculation unit 23, and the exposure correction setting unit 24 can be constituted by, for example, a microcomputer (μC) 25. In this case, each unit operates according to an exposure control program held in a built-in memory. Note that each of the exposure control unit 22, the exposure calculation unit 23, and the exposure correction setting unit 24 can be configured by hardware, but the functions of the units 22 to 24 are realized by the description of a program that operates the microcomputer 25 below. Explain the case.

  An external switch 30 is connected to the microcomputer 25. As shown in FIG. 2, the external switch 30 includes, for example, a release switch (SW) 32 disposed on the upper surface of the camera body 31, a display switching SW 33 and an exposure correction SW 34, and various setting switches 35 disposed on the rear surface. including. Note that an electronic viewfinder as the display unit 10 is disposed on the back surface.

  When a power switch (not shown) is operated, the CCD 4 captures an image, and the monitor image in which the pixel data is thinned out by the image processing unit 8 to reduce the data amount is automatically displayed on the electronic viewfinder. When a desired automatic exposure correction mode or manual exposure correction mode selected from several prepared by operating the display switching SW 33 during the display period, the AE program stored in the exposure control unit 12 is stored. A diaphragm by the motor driver 20, a shutter speed by the TG 21 and the like are set so that the predetermined exposure value (EV value) is read out. Further, when the release SW 32 is operated, the image sensor 4 controls the signal charge accumulation time according to the shutter speed instructed from the microcomputer 25, thereby realizing an electronic shutter and imaging in the set exposure mode. Is done. Accumulated charges are output from the CCD 4 to the analog signal processing circuit 5 as video signals, where predetermined analog signal processing such as signal inversion, removal of random noise by CDS and setting of clamp level, removal of high frequency noise, signal amplification, etc. Is executed. The processed video signal is sent to the ADC 6, converted into a digital signal expressed by, for example, 8-bit gradation for each pixel of each color of RGB, and stored in the SDRAM 7 for each screen, for example. The gamma conversion unit 13 has a gradation conversion characteristic defined by a predetermined correction curve. The video digital data read from the SDRAM 7 is sent to the image processing unit 8 after the luminance level is corrected by the gamma conversion unit 13. The image processing unit 8 performs various processes other than the gradation correction, for example, various processes such as resizing by thinning or interpolation processing, and displays them on the display unit 10 and also stores them in a built-in or portable flash memory. It is stored in the medium 11. These processes are executed under the control of the microcomputer 25 that also serves as an exposure control means.

In this embodiment, the video signal after the image processing can be inputted two histogram generator 9 _-1 and 9 _-2 are provided. The first histogram generation unit _9-1 is means for generating histogram data of an absolute luminance distribution corresponding to the absolute luminance together with the exposure calculation unit 23, and the second histogram generation unit _9-2 is a relative luminance distribution corresponding to the relative luminance. Means for generating the histogram data. Here, the “absolute luminance distribution” refers to a luminance distribution of light that can be input from the subject to the image sensor (CCD here) 4 and subjected to photoelectric conversion. The “relative luminance distribution” means a luminance distribution obtained through photoelectric conversion by the CCD 4 and other signal processing. As information on the brightness of the subject, the absolute luminance distribution is more direct than the relative luminance distribution.

Here, in the present example, two readout paths for histogram processing from the SDRAM 7 are provided. The second path is for normal relative brightness distribution display is a path to send data to the second histogram generator 9 _-2 through the gamma conversion unit 13 and image processing unit 8 from the SDRAM 7. First path, for the absolute luminance distribution display is a path for sending sends the data to the image processing unit 8 without going through the gamma conversion unit 13 from the SDRAM 7, the data in the first histogram generator 9 _-1 after treatment . In the case where a part of the image processing unit 8 a gamma conversion unit 13, a gamma converting whether to perform gamma conversion is controlled by a microcomputer 25, to the data to be sent to the first histogram generator 9 _-1 You may make it not do.

In this embodiment, the absolute luminance distribution is generated using the EV value set at the time of shooting or monitoring. To illustrate a more detailed and preferable method, it is assumed that the imaging screen is composed of an area of an arbitrary size, for example, each area when divided into N pieces in the horizontal direction and M pieces in the vertical direction. Further, the average relative luminance data of an arbitrary i-th region at this time is Y [i]. The EV value (Bv) is uniquely determined from the aperture value (Av) when the relative luminance data Y [i] is obtained, the shutter control value (Tv), and the sensitivity (Sv) corresponding to the conversion efficiency of the image sensor. Further, in exposure correction, an appropriate exposure level is determined according to the type of exposure mode or the type of optical lens. For example, when the relative luminance data is expressed by an 8-bit gradation of 0 to 255, normally, the central 128 luminance level is set as an appropriate correction level, and the appropriate level is set from the center of the gradation D range as necessary. Use a shifted setting.
Under these assumptions, first, an EV conversion is performed in which a difference obtained by subtracting the value of the appropriate correction level from the average relative luminance data Y [i] of the i-th region is correlated with the EV value. I do. Assuming that the value after EV conversion is ΔY [i], this is an EV value reflecting a variation in luminance from when the image is captured until the relative luminance data Y [i] is extracted. Therefore, the absolute luminance Bv [i] of an arbitrary i-th region can be obtained by the following equation.

[Formula 1]
Bv [i] = Bv + ΔY [i] (1)

Here, Bv = Tv + Av−Sv, and as is well known, the shutter control value (Tv) has a relationship of shutter speed (T) and T = 2 ^Tv , and the aperture value (Av) is the F value. F ² = 2 ^Av .

Next, the histogram data of the absolute luminance distribution is generated by sequentially performing the calculation according to the equation (1) for all the N × M regions. This calculation is executed by the exposure calculation unit 23 shown in FIG. At this time, the exposure calculation unit 23 uses, for example, relative luminance data for each screen through a first path in which gamma conversion is skipped from the SDRAM 7 for calculation. The EV value is the value at the time of exposure from which the relative luminance data was obtained. Exposure calculation unit 23 outputs the absolute which is the result of the operation luminance Bv [i] in the first histogram generator _{9 -1.} The first histogram generator 9 _-1 generates histogram data from the data of the absolute luminance Bv [i] received, a predetermined display format, generates a display image of the absolute luminance distribution, for example, a bar chart or form of a line graph. The generated absolute luminance distribution display screen data is sent to the display unit 10.

On the other hand, the second histogram generator 9 _-2 receives the relative luminance data from the second path through the gamma conversion unit 13 and image processing unit 8 from the SDRAM 7, the display screen of the conventional relative brightness distribution based on Is generated and output to the display unit 10.
Under the control of the microcomputer 25, the display unit 10 superimposes and displays the display image of the input absolute luminance distribution or relative luminance distribution on the monitor image or the captured image. In this case, it is necessary to provide the display unit 10 with a simple image composition function. However, the display images of the absolute luminance distribution and the relative luminance distribution from the first and second histogram generation units _9-1 and _9-2. May be output to the image synthesizing unit 8, and a display image with any luminance distribution may be synthesized with the monitor image or the captured image.

Display unit 10 (or the image synthesis unit 8) has a function of switching the first and second histogram generator 9 _-1 and 9 _-2 under the control of the microcomputer 25.
Details of this switching control will be described below with reference to the flowchart shown in FIG. Although the case where the display unit 10 has a display switching function will be described here, the image processing unit 8 may execute the function.

  While the monitor image or the captured image is being displayed, the microcomputer 25 shown in FIG. 1 monitors whether or not the display switching SW 33 (see FIG. 2) of the external switch 30 is operated in step ST1. When the display switching SW is not operated (the determination in step ST1 is “N”), the process is once completed and started again. Therefore, the microcomputer 25 repeatedly executes the determination in step ST1. When the operation of the display switching SW is detected in step ST1 (the determination in step ST1 is “Y”), the microcomputer 25 commands to switch the display mode depending on the operation, for example, whether the button is pressed once or twice. Is output to the display unit 10 (step ST2). The display unit 10 switches and displays the histogram display of the luminance distribution according to a command from the microcomputer 25 or turns off the histogram display of the luminance distribution. Step ST3-1 shown in FIG. 3 is a normal histogram display for displaying a relative luminance distribution, step ST3-2 is a histogram display of an absolute luminance distribution, and step ST3-0 is a histogram display OFF. The histogram display screen once displayed is maintained until the display switching SW 33 is operated in step ST1 and a display mode different from that currently displayed is instructed in step ST2.

FIG. 4A shows an example of a display image when the histogram display is OFF, FIG. 4B shows a normal relative luminance distribution histogram display, and FIG. 4C shows an absolute luminance distribution histogram display. Show.
In these figures, the shutter speed (1/60) and the F value (F2.8) are displayed as image information. This is because the various setting SW (cross key switch) 35 shown in FIG. It is an example of display information of an EV value that is set by operation or predetermined in an automatic exposure correction mode. In the absolute luminance distribution histogram display shown in FIG. 4C, the scale of the EV value is displayed on the horizontal axis, and the current EV value is indicated by an arrow. The EV value scale display and the current EV value indication display correspond to the horizontal axis of the histogram display screen of the absolute luminance distribution by the EV value detection means (in this example, one function of the microcomputer 25) detecting the EV value. It is realized by letting. This instruction of the current EV value is particularly useful for determining whether to increase or decrease the EV value in the manual exposure correction mode.

The conventional histogram display displays relative luminance distribution information from the maximum value to the minimum value of the luminance of the captured image as shown in FIG. 4B, and the absolute luminance distribution was unknown. Some cameras display a shutter control value and an aperture value at the time of shooting at the same time as the histogram. From this, absolute luminance (EV value set at the time of exposure, hereinafter referred to as EV value when this EV value is simply referred to as EV value) is calculated. But it is difficult to grasp intuitively.
In the present embodiment, as shown in FIG. 4C, the horizontal axis of the histogram of the luminance distribution is set to the absolute luminance (EV value by calculation, hereinafter referred to as the calculated EV value) to visually determine the absolute luminance level. Can be displayed. Therefore, for example, the photographer normally selects the histogram display of the relative luminance distribution, switches to the histogram display of the absolute luminance distribution for confirmation when the EV value is to be changed, and performs the change operation. It can be used.

In such absolute luminance display, there is an advantage that information on the brightness of the subject can be displayed more directly than in the conventional relative luminance display. In addition, in the calculation of absolute luminance, the relative luminance level is used as a parameter. However, since absolute luminance is basically an EV value (strictly, an calculated EV value) itself, the absolute luminance changes linearly with respect to the EV value. To do. Therefore, it is easy to predict how to shift the absolute luminance distribution when the EV value is changed. If the photographer changes the EV value in which direction and how much, the luminance display distribution becomes a desired one. There is an advantage that it can be easily and sensibly grasped by several operations. Although the relative luminance level is used for the calculation of the absolute luminance, the gamma conversion process is skipped when the relative luminance is read, and therefore the use of the relative luminance level itself is the EV value of the distribution shape shift described above. There is no loss of linearity with respect to change.
For this reason, in the present embodiment, overexposure and underexposure are effectively prevented by changing the EV value, and imaging with the intended brightness becomes easy.

Next, setting of exposure conditions will be described.
When determining exposure conditions, photometry is generally performed by a photometry unit of a digital camera, and the aperture and shutter speed are adjusted based on the photometry results. Although not shown in FIG. 1, the photometry unit is a means for obtaining a luminance average of a specific range at an angle of view in which the subject is placed in a specific range (in the target frame) in the central portion of the monitor image.
In the automatic exposure correction (program AE) mode, this photometry result, for example, aperture priority AE mode, aperture priority program AE mode (so-called landscape mode), aperture opening priority program AE mode (so-called portrait mode), high-speed shutter speed priority program The EV value is selected according to a desired AE mode selected from the AE mode (so-called sports mode) or the like. More specifically, when a desired AE mode is selected by operating the exposure correction SW 34 or various setting SW 35 shown in FIG. 2, the exposure correction setting unit 24 shown in FIG. 1 detects and holds this. A desired EV value is read from the AE program diagram, and the exposure control unit 22 executes control according to the EV value for the motor driver 20, the TG 21, and the variable gain amplifier in the analog signal processing circuit 5. At this time, the aperture is controlled by the motor driver 20, the control value such as the shutter speed is controlled by the TG 21, and the signal level is controlled by the variable gain amplifier.

  In the present embodiment, since the exposure calculation unit 23 that calculates the absolute luminance distribution divides the image into small N × M areas and obtains the average of the respective luminances, for example, Since the luminance average of the area is obtained, there is an advantage that it is not necessary to separately provide a photometric unit. That is, the exposure calculator 23 can also function as a spot reflection photometer (photometer).

  Next, an automatic switching function for displaying and hiding the histogram display screen during exposure correction will be described. FIG. 5 is a flowchart showing this switching operation. FIGS. 6A, 6B, and 6C show a monitor image without a histogram display, a monitor image with a histogram display with a specified EV value, and an EV value after changing the shutter speed, respectively. The monitor image with a histogram display is shown.

  Assume that a predetermined program AE mode or a manual exposure correction mode is selected by operating an exposure correction SW as a mode selection unit shown in FIG. 2 and operating various setting SWs as necessary. In step ST10 shown in FIG. 5, the operation of the exposure correction SW is detected by the exposure correction setting unit 24 as the mode detecting means shown in FIG. The exposure correction setting unit 24 has a function of detecting the type of exposure mode, and reads an EV value necessary for the detected exposure mode from the AE program diagram in the built-in memory or calculates it by the exposure calculation unit 23. Let

  When the detection result in step ST10 is “Y”, the exposure correction setting unit 24 monitors whether or not exposure correction is being set in step ST11. In step ST11, for example, it is determined that the exposure correction setting has been stopped when the exposure correction SW is operated again to be turned off, or when the shutter is immediately released. Alternatively, when the exposure correction value (aperture value, shutter speed, etc.) is not changed during a certain time, it is determined that the exposure correction setting is stopped.

  If the result of determination in step ST11 is “Y”, that is, it is determined that exposure correction is being set, the display is shifted to the exposure correction setting state in exposure correction setting step ST12, and then the display mode is normal in step ST13. Is judged. Here, the normal display mode is a case where a monitor image is displayed on the display unit 10, and other setting operations are performed when the monitor image is displayed on the display unit 10 such as a setting menu. The determination in step ST13 is “N”, and the process is once completed, and the exposure correction SW re-operation waiting state in step ST10 is entered.

When the determination in step ST13 is “Y”, it is a normal display mode. Therefore, in step ST14, the microcomputer 25 gives the histogram display permission to the display unit 10, whereby the histogram display screen is superimposed on the monitor image. .
The photographer can change the EV value by operating the various operation switches 35 shown in FIG. 2 while viewing the histogram displayed as shown in FIG. Since FIG. 6 shows a case where the shutter speed is manually changed, a histogram display example of the relative luminance distribution is shown, but the same operation is also performed in the histogram display of the absolute value luminance distribution shown in FIG. Is possible. In FIG. 6, for the convenience of the photographer, the EV value when the shutter speed and the F value are changed is also displayed. In FIG. 6B, since it is before the change, the EV value is displayed as “0.0”, and after the change in FIG. 6C, the EV value is changed to “+1.0”.

  On the other hand, when the determination in step ST11 shown in FIG. 5 is “N”, it is determined that the exposure correction setting has been stopped. Therefore, after the exposure correction setting state is canceled in step ST15, the exposure correction setting unit 24 In step ST16, it is determined whether the display mode is the normal display mode as described above. When this determination is “Y”, the histogram display is turned off, and when it is “N”, the process is temporarily ended, and the process waits for the operation of the exposure correction SW in step ST10.

For the photographer, the fact that the histogram is always displayed at the time of exposure correction may interfere with framing, and it is troublesome to perform an operation for hiding the histogram each time when it is disturbed.
In this embodiment, since the display and non-display control of the histogram display screen is automatically executed, even when the histogram display remains at the stage where the exposure is corrected and the shutter is pressed, the non-display operation is performed. There is an advantage that it is easy to use without having to do it.

  The present invention can be widely applied to applications such as a digital camera and a video camera having a function of a digital electronic still camera or a portable wireless terminal.

It is a block diagram which shows schematic structure of the digital camera concerning embodiment of this invention. It is a figure which shows arrangement | positioning of the switch and electronic viewfinder of a digital camera. It is a flowchart which shows switching control of a histogram display. It is a figure which shows the example of a display image in the case of the histogram display of relative luminance distribution in the case of histogram display OFF, the case of the histogram display of absolute luminance distribution. It is a flowchart which shows the automatic switching control of the display of a histogram display screen at the time of exposure correction | amendment, and non-display. It is a figure which shows the example of a display image which shows the monitor image without a histogram display, the monitor image with a histogram display by the regulation AE value, and the monitor image with a histogram display by the AE value after shutter speed change.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Digital camera, 2 ... Lens, 3 ... Aperture mechanism, 4 ... Image sensor, 5 ... Analog signal processing circuit, 6 ... Digital-analog conversion circuit, 7 ... Image memory, 8 ... Image processing part, _9-1 ... 1st DESCRIPTION OF SYMBOLS 1 Histogram generation part, _9-2 ... 2nd histogram generation part, 10 ... Display part, 11 ... Storage medium, 12 ... Exposure control mechanism, 13 ... Gamma conversion part, 20 ... Motor driver, 21 ... Timing generation circuit, 22 ... Exposure control unit, 23 ... Exposure calculation unit, 24 ... Exposure correction setting unit, 25 ... Microcomputer, 30 ... External switch, 31 ... Camera body, 32 ... Release SW, 33 ... Display switch SW, 34 ... Exposure correction SW, 35 ... Various setting SW

Claims (7)

An image sensor;
Histogram generating means for creating histogram data of an absolute luminance distribution corresponding to the luminance distribution of light that can be input to the image sensor and photoelectrically converted at the time of shooting or monitoring;
A digital camera comprising: display means for displaying histogram data of the absolute luminance distribution generated by the histogram generation means. Second histogram generating means for generating histogram data of a relative luminance distribution based on an output signal of the image sensor;
A selection means for selecting display of absolute luminance distribution and display of relative luminance distribution;
2. The digital camera according to claim 1, wherein the display unit switches between display of an absolute luminance distribution and display of a relative luminance distribution according to the selection by the selection unit. The histogram generation means adds the difference obtained by subtracting an appropriate luminance level from the relative luminance of the output signal of the image sensor to the EV value set at the time of imaging or monitoring, and generates histogram data of the absolute luminance distribution. The digital camera according to claim 1, wherein the digital camera is a digital camera. EV value detecting means for detecting an EV value representing the exposure amount of the digital camera at the time of shooting or monitoring is further provided.
The digital camera according to claim 1, wherein the display unit displays an index with respect to the EV value on the display of the absolute luminance distribution. Absolute luminance detecting means for detecting the absolute luminance of a specific area in the imaging screen at the time of shooting or monitoring from the histogram data of the absolute luminance distribution;
The digital camera according to claim 1, wherein the display unit displays an index corresponding to a distribution range of the EV value in the specific area on the display of the absolute luminance distribution. A mode selection means for selecting various modes by operation; and a mode detection means for detecting the mode selected by the mode selection means,
The display means displays a histogram together with a photographed image or a monitor image on the display means when the mode detection means detects that the exposure correction mode is selected, and a mode different from the exposure correction mode by the mode selection means. 3. The digital camera according to claim 1, wherein when the mode detection unit detects that the button is selected, the histogram in the display screen of the display unit is hidden. Means for generating a histogram of luminance distribution;
Display means for displaying the captured image;
Mode selection means for selecting various modes by operation;
Mode detection means for detecting the mode selected by the mode selection means,
When the mode detection unit detects that the exposure correction mode is selected, the histogram is displayed together with the photographed image on the display unit, and a mode different from the exposure correction mode is selected by the mode detection unit. A digital camera characterized in that, when the mode detection means detects, the histogram in the display screen of the display means is hidden.

Images