JP4554094B2 - Imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus capable of reproducing an image having a substantially wide dynamic range.
[0002]
[Prior art]
Various image pickup apparatuses that electrically pick up subject images have been proposed, and a digital still camera (DSC) as an image pickup apparatus forms an image on an image pickup surface of a solid-state image pickup device via a lens. The optical image is converted into electrical information by the solid-state imaging device to generate an image.
[0003]
Since the solid-state image sensor of such a digital still camera is currently designed to increase the number of pixels, an image with higher resolution than before is generated, but on the other hand, the dynamic range of the element itself Therefore, there is a problem that the resulting image has a narrow latitude (reproduction range from a bright part to a dark part).
[0004]
What is important for properly reproducing images within such a narrow dynamic range is an AE (automatic exposure setting) function that sets appropriate exposure conditions (exposure time, aperture, etc.) according to the shooting scene. There have been some proposals using the AE function.
[0005]
As an example of such a technique, Japanese Patent Laid-Open No. 6-38092 describes a technique relating to a video camera for setting an appropriate exposure condition and a photometric method thereof, and more specifically, in a horizontal scanning period. It is a technique for performing photometry using an integral value obtained by integrating luminance information from video information over a photometric period, which is determined to be within a predetermined range. Further, the publication describes a technique for changing the exposure condition when the number of times that the integrated value of the luminance information is determined not to be within the predetermined range exceeds a predetermined number.
[0006]
On the other hand, in order to acquire image information with a wide dynamic range from a solid-state imaging device with a narrow dynamic range, a technique for performing a plurality of exposure operations with different exposure amounts is conventionally known.
[0007]
Such a technique will be described with reference to FIG. FIG. 8 is a diagram showing a state in which a subject having a luminance difference is exposed multiple times with different exposure amounts.
[0008]
FIG. 8A shows a shooting scene in which a person who is a dark main subject is located almost in the center with a bright outdoor landscape or the like as a background. When such a landscape is imaged with a solid-state imaging device with a narrow dynamic range, a low exposure amount exposure in which the background becomes clearer as shown in FIG. 8B, and FIG. The background is obtained by combining the background portion in the image of FIG. 8B and the portion of the person in the image of FIG. 8C. A wide dynamic range image in which both the person and the person are projected more clearly is generated.
[0009]
Even when a wide dynamic range image is generated using such a multiple exposure technique, a dynamic range in which a dark main subject (person) and a bright background are mixed in a backlight state as shown in FIG. When shooting a wide scene, the AE function is important in order to reproduce an optimal image.
[0010]
Several techniques for controlling photographing so that both the main subject and the background are appropriately exposed in accordance with such a photographing scene with a wide dynamic range have been proposed, for example, Japanese Patent Laid-Open No. 7-298142. Describes an imaging apparatus having a gradation control function for appropriately exposing both a main subject and a background in a shooting scene such as backlight. More specifically, the technology described in the publication includes gradation control means for switching and controlling timing information for setting the optical information storage time corresponding to the high luminance portion and the low luminance portion based on the luminance information of the video information. It has become.
[0011]
[Problems to be solved by the invention]
However, in the one described in Japanese Patent Laid-Open No. 6-38092, when the exposure condition is changed when the number of times that the integrated value of the luminance information is determined to be outside the predetermined range exceeds the predetermined value, the same method is used thereafter. However, in the scene as shown in FIG. 8, it is necessary to determine whether the light metering is performed for the bright part or the dark part for the metering after the first exposure condition is changed. Further, with this means, the exposure condition for only one of the bright part and the dark part is made appropriate, and the other becomes an inappropriate exposure condition.
[0012]
Moreover, in the thing of the said Unexamined-Japanese-Patent No. 7-298142, the exposure amount is varied and multiple exposure operation | movement is performed, About discrimination | determination of the high-intensity part and low-intensity part at this time, Although the corresponding part is manually specified for each block obtained by dividing the screen, it is not clear how to automatically specify the high luminance part and the low luminance part. In addition, it is not clarified how to deal with the discrimination between the high luminance portion and the low luminance portion when the shooting scene is switched and changed. Furthermore, since it is necessary to constantly read information relating to the shooting scene from a solid-state imaging device or the like, there is a problem that power consumption increases as a result.
[0013]
On the other hand, there may be a means to prepare a plurality of exposure settings according to the situation of the shooting scene in advance so that the user can select as desired from these exposure settings. However, if there is no experience or knowledge to some extent, Since it is difficult for the user to subjectively determine whether the setting is optimal for the actual shooting scene while taking into account the difference in brightness and the like, it is not sufficiently practical.
[0014]
The present invention has been made in view of the above circumstances, and can automatically shoot by setting exposure conditions suitable for the dynamic range that the shooting scene can have, and as a result, adapted to the dynamic range of the shooting scene. An object of the present invention is to provide an imaging apparatus capable of reproducing an image.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the image pickup apparatus according to the first invention is set prior to performing the main shooting. Information on multiple exposures with different exposures Information acquisition means for acquiring information on the dynamic range of the shooting scene based on the information acquisition means, and the information acquisition means Regarding the dynamic range of shooting scenes Based on information analysis means for analyzing information and results analyzed by the information analysis means Multiple exposures with different exposures Shooting setting means for setting conditions, and actual shooting set by the shooting setting means Multiple exposures with different exposures Imaging means for performing actual imaging according to conditions.
[0018]
First 2 An imaging apparatus according to the invention is the above-mentioned first. 1 In the imaging apparatus according to the invention, the imaging setting unit determines whether or not the exposure condition when the information acquisition unit obtains information from the analysis result of the information analysis unit, and determines that the exposure condition is not appropriate. In this case, the exposure condition is changed, and the information acquisition means has control means for controlling to acquire information again.
[0019]
First 3 An imaging apparatus according to the invention is the above-mentioned first. 2 In the imaging apparatus according to the invention, when the control means changes the exposure condition determined to be inappropriate from the analysis result of the information analysis means, the exposure condition is darker than the current exposure condition or brighter than the current exposure condition. The condition is changed to either one or both.
[0021]
First 4 An imaging apparatus according to the invention is the above-mentioned first. 1 In the imaging apparatus according to the invention, the photographing setting means includes an adjusting means for adjusting the ratio of the different exposure conditions in the main photographing conditions in which the exposure is performed a plurality of times under different exposure conditions obtained from the analysis result of the information analyzing means. Is included.
[0022]
First 5 An imaging apparatus according to the invention is the above-mentioned first. 4 In the imaging apparatus according to the invention, the adjusting means adjusts the main photographing condition according to the dynamic range of the photographing scene obtained as an analysis result of the information analyzing means.
[0023]
First 6 An imaging apparatus according to the invention is the above-mentioned first. 4 In the imaging apparatus according to the invention, the adjusting means refers to the actual photographing condition obtained from the analysis result of the information analyzing means, and adjusts the actual photographing condition when it is determined that adjustment is necessary.
[0024]
First 7 An imaging apparatus according to the invention is the above-mentioned first. 6 In the image pickup apparatus according to the invention, the main photographing condition referred to by the adjusting means includes at least one of information relating to the exposure amount and aperture information.
[0025]
First 8 An imaging apparatus according to the invention is the above-mentioned first. 4 The image pickup apparatus according to the present invention further includes flash light emitting means for irradiating light toward the object to be photographed, and the adjusting means adjusts the main photographing condition according to the use state of the flash light emitting means.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
1 to 4 show a first embodiment of the present invention, and FIG. 1 is a block diagram showing a basic configuration of an electronic camera.
[0027]
This electronic camera is composed of a single-plate color CCD or the like having an electronic shutter function, and forms an image of the subject on the image pickup device 1 as a photographing means for photoelectrically converting a subject image and outputting it as image information. Noise components are removed by the lens 2, a diaphragm / shutter mechanism 3 that controls the passage range and passage time of the light beam that has passed through the lens 2, and a correlated double sampling circuit (not shown) after being output from the imaging device 1. An amplifier 4 that amplifies the image information performed, an A / D converter 5 that converts analog information amplified by the amplifier 4 into digital information, and various types of information digitized by the A / D converter 5 The camera information processing circuit 6 that performs the above processing and the digital output from the A / D converter 5 receive AF (auto focus) information and AE (auto exposure). Information, AF, AE, AWB detection circuit 7 for detecting AWB (auto white balance) information, a compression circuit (JPEG) 9 for compressing image data from the camera information processing circuit 6, and compression by the compression circuit 9 A memory card I / F 14 that performs control for recording the recorded image data in a memory card 15 to be described later, and a memory card 15 that includes a nonvolatile recording medium that records image data under the control of the memory card I / F 14 A DRAM 11 used as a working memory when performing color processing of image data, a memory controller 10 for controlling the DRAM 11, and image data recorded on the memory card 15 as a personal computer (PC) 17. PCI / F16 which is an interface for transferring to the A display circuit 12 that controls the display 13, and an LCD 13 that reproduces and displays the image data recorded on the memory card 15 under the control of the display circuit 12, and displays various shooting states of the electronic camera, and the like. In order to set various photographing modes, a strobe 19 as a flash light emitting means for emitting illumination light for illuminating a subject, a timing generator (TG) 18 for generating a timing pulse for driving the image pickup device 1, and the like. And an input key 20 having a trigger switch for inputting a shooting operation instruction and the like, and exposure in the main shooting in a wide dynamic range shooting mode to be described later upon receiving a digital output from the A / D converter 5. A shutter control information circuit 21 for setting the conditions and outputting information related to the exposure amount such as the exposure time; A switch 22 for controlling the input of information relating to the exposure amount according to the mode, the camera information processing circuit 6, the compression circuit 9, the memory controller 10, the display circuit 12, the memory card I / F 14, the PCI / F 16, and the bus line 23. And receiving the detection result of the AF, AE, AWB detection circuit 7, the input by the input key 20, the control information of the shutter control information circuit 21, or the light emission information by the strobe 19, etc. A CPU 8 for controlling the entire electronic camera including the lens 2, the aperture / shutter mechanism 3, the switch 22, the camera information processing circuit 6, the strobe 19, the input key 20, and the circuits connected to the bus line 23; It is configured.
[0028]
In this electronic camera, one image is shot with a single exposure and the image is used as image data, and multiple images with different exposure amounts are exposed close in time, and these images are combined. And a wide dynamic range shooting mode for obtaining a single wide dynamic range image.
[0029]
The setting of these shooting modes is automatically determined by the user manually selecting by operating the input key 20 or by the CPU 8 detecting overexposure of image information output from the image sensor 1. The CPU 8 controls the shooting operation in accordance with the selected shooting mode.
[0030]
That is, when the normal shooting mode is selected, image information for one screen is acquired from the image sensor 1 by one exposure by the shooting operation, while when the wide dynamic range shooting mode is selected. The image information for a plurality of screens (for example, two screens) having different exposure amounts is acquired from the image sensor 1 by a plurality of exposures for one subject, and image data corresponding to the shooting mode is acquired by the camera information processing circuit 6. Processing is to be performed.
[0031]
The exposure is performed by an electronic shutter function of the image sensor 1 or by a known means that combines the electronic shutter function and the aperture / shutter mechanism 3.
[0032]
Further, when the normal photographing mode is selected, the CPU 8 calculates shutter control information for performing exposure of one image based on the detection result by the AF, AE, and AWB detection circuit 7 and uses the result as the timing generator 18. The switch 22 is driven so as to transmit to the terminal.
[0033]
On the other hand, when the wide dynamic range shooting mode is selected, the shutter control information circuit 21 calculates shutter control information for exposing a plurality of images having different exposure amounts, and transmits the result to the timing generator 18. The switch 22 is driven.
[0034]
Next, FIG. 2 is a block diagram showing a detailed configuration of the shutter control information circuit 21.
[0035]
In this embodiment, when the wide dynamic range shooting mode is selected, the shutter control is performed on the premise that the exposure is performed twice under different exposure conditions.
[0036]
When setting the main shooting conditions, luminance information of the shooting scene is used as information regarding the dynamic range of the shooting scene.
[0037]
First, a pre-shooting operation is performed based on exposure conditions set by a normal AE operation or the like, and luminance information relating to a shooting scene is acquired. As a result, the A / D converter 5 outputs luminance information aa relating to the shooting scene.
[0038]
The scene information distribution calculation circuit 31 as information acquisition means inputs the luminance information aa, calculates the distribution (histogram) of luminance information, and outputs this as luminance distribution information bb.
[0039]
The scene information analysis circuit 32 serving as information analysis means inputs the luminance distribution information bb, and calculates a histogram frequency in the luminance part indicating the dark part (blackout) and the luminance part indicating the bright part (overexposure). And information on the analysis result is output as luminance analysis information cc.
[0040]
The exposure condition determination circuit 33, which is a photographing setting means and a control means, inputs this luminance analysis information cc, and determines whether or not the currently set exposure condition is appropriate.
For this determination, “change the current exposure condition and perform the pre-shooting operation again” (“exposure condition change”) or “set the current exposure condition as the main shooting condition” (“determine exposure condition”) Is determined as the determination result, and control is performed to change the output destination of the information indicating the exposure condition in accordance with the contents, and at the same time, the determination result is output as the appropriate exposure information dd and transmitted to the CPU 8. To do.
[0041]
First, when the determination result of the exposure condition is “determination of exposure condition”, the exposure condition determination circuit 33 outputs the main photographing exposure information ff as the exposure condition information in the main photographing. A main photographing shutter control information generation circuit 35 as photographing setting means inputs the main photographing exposure information ff, generates shutter control information when performing main photographing, and outputs the shutter control information as main photographing shutter control information hh.
[0042]
On the other hand, when the determination result of the exposure condition is “exposure condition change”, the exposure condition determination circuit 33 outputs the changed exposure information ee as the changed exposure condition information. The exposure condition change circuit 34, which is a photographing setting means and a control means, receives the changed exposure information ee, and after changing the current exposure condition, the shutter corresponding to the changed exposure condition for performing the pre-photographing operation again. Control information is generated and output as pre-shooting shutter control information gg.
[0043]
The shutter control information changeover switch 36 performs switch driving so as to switch the information to be input based on the control information ii output from the CPU 8 that has received the appropriate exposure information dd from the exposure condition determination circuit 33. Thus, by switching the shutter control information changeover switch 36, the pre-shooting shutter control information gg or the main shooting shutter control information hh is output as the shutter control information kk and transmitted to the switch 22.
[0044]
Further, the CPU 8 determines whether to perform the pre-shooting operation again or to enter the main shooting standby state based on the determination result indicated by the appropriate exposure information dd.
[0045]
That is, if the exposure appropriate information dd indicates “exposure condition change”, the CPU 8 causes the pre-shooting operation to be performed again based on the shutter control information kk set through the exposure condition change circuit 34. Thus, the luminance information related to the shooting scene is acquired, and the luminance control aa obtained from the A / D converter 5 is caused to cause the shutter control information circuit 21 to perform the above-described process again.
[0046]
On the other hand, when the appropriate exposure information dd indicates “determining exposure conditions”, the CPU 8 performs wide dynamic range shooting based on the shutter control information kk set through the main shooting shutter control information generation circuit 35. A transition is made to the actual photographing standby state in which the standby is possible.
[0047]
FIG. 3 is a flowchart showing processing in the shutter control information circuit 21.
[0048]
3 will be described with reference to each piece of information shown in FIG.
[0049]
When the operation starts, first, the scene information distribution calculation circuit 31 calculates a histogram of the luminance information aa relating to the shooting scene (step S1). Here, the calculated histogram corresponds to the luminance distribution information bb shown in FIG.
[0050]
Next, the scene information analysis circuit 32 refers to the calculated histogram and calculates the frequency of the luminance portion indicating the dark portion and the luminance portion indicating the bright portion (step S2). Here, the calculated frequency and the corresponding luminance correspond to the luminance analysis information cc shown in FIG.
[0051]
Subsequently, the frequency corresponding to the brightness of the bright portion (dark portion) is compared with a predetermined value (for example, 10% of the total number of histogram frequencies, etc.) (step S3).
[0052]
In this step S3, when it is determined that the frequency corresponding to the brightness of the bright part (dark part) is equal to or greater than a predetermined value, it is determined that overexposure (blackout) occurs in shooting under the current exposure conditions. The exposure condition is changed and set to be darker (brighter) by 1 EV than the current exposure condition (step S4). Here, the exposure condition processed in step S4 corresponds to the changed exposure information ee shown in FIG.
[0053]
Next, the exposure condition changing circuit 34 generates pre-shooting shutter control information gg for performing pre-shooting again based on the changed exposure condition (step S5).
[0054]
Then, the generated pre-shooting shutter control information gg is output from the shutter control information changeover switch 36 as shutter control information kk, and the CPU 8 is instructed to execute the pre-shooting operation using the shutter control information kk again ( Step S6). Here, the instruction to the CPU 8 in step S6 corresponds to the appropriate exposure information dd shown in FIG.
[0055]
On the other hand, if it is determined in step S3 that the frequency corresponding to the brightness of the bright part (dark part) is less than a predetermined value, the shooting under the current exposure condition is appropriate for a relatively bright (dark) subject. Based on the current exposure condition (that is, the main photographing exposure information ff shown in FIG. 2 above), the main photographing shutter control information generation circuit 35 performs the main photographing shutter control for performing the main photographing. Information hh is generated (step S7).
[0056]
Then, the CPU 8 indicates that the actual photographing shutter control information hh thus generated is output as shutter control information kk from the shutter control information changeover switch 36, and that the main photographing can be performed with this shutter control information kk (the standby state). (Step S8). Here, the instruction to the CPU 8 in step S8 corresponds to the appropriate exposure information dd shown in FIG. 2 as in step S6.
[0057]
Thus, when the process of step S6 or step S8 is performed, this process is terminated.
[0058]
Here, in the case of performing exposure twice under different exposure conditions as in the present embodiment, the photographing operation incorporating the processing of FIG. 3 proceeds as follows.
[0059]
As described above, first, the first exposure condition is set by normal AE information or the like, and the pre-shooting operation is performed.
[0060]
After that, as shown in FIG. 3, both the process related to the bright part and the process related to the dark part are performed.
[0061]
Here, when both the bright portion and the dark portion are in the main shooting standby state, it is useless to shoot twice under the same exposure condition, so that only one shooting is performed. (This is the same shooting as the normal shooting mode).
[0062]
Further, when the exposure condition is changed as shown in step S4 in both the bright part and the dark part, the exposure condition is darker by 1 EV than the first exposure condition (-1 EV exposure condition) and the same 1 EV. After changing to the exposure condition (+1 EV exposure condition), the pre-photographing operation is performed again for each.
[0063]
Thereafter, the process as shown in FIG. 3 is performed. In the case of the -1 EV exposure condition, the process is performed only for the bright part, and the change of the exposure condition as shown in step S4 is performed here. In this case, the pre-shooting operation is performed again by changing the exposure condition to darker by 1 EV (that is, −2 EV exposure condition), and thereafter, the process shown in FIG. 3 is performed only for the bright part.
[0064]
On the other hand, in the case of the +1 EV exposure condition, only the dark portion is processed. Here, when the change of the exposure condition as shown in step S4 is executed, the exposure condition brighter by 1 EV (that is, +2 EV exposure condition). And the pre-photographing operation is performed again, and thereafter, the process as shown in FIG. 3 is performed only for the dark part.
[0065]
Further, when the change of the exposure condition as shown in step S4 is executed only in one of the bright part and the dark part, if the change is related to the bright part, the exposure condition is darker by 1 EV than the first exposure condition. (-1EV exposure condition), and if it is a change related to a dark part, it is changed to an exposure condition (+ 1EV exposure condition) brighter by 1 EV than the first exposure condition, and thereafter, the corresponding part is processed. It has come to go.
[0066]
Next, FIG. 4 is a diagram showing an image of processing performed in the shutter control information circuit 21.
[0067]
First, by pre-shooting operation based on the first exposure condition (for example, exposure time 1/250 seconds), luminance information related to the shooting scene as shown in FIG. The luminance information histogram at this time has a distribution as shown in FIG. 4B, for example. In this example, the dark portion DK (the portion on the left of the left dotted line) and the bright portion BR (the right dotted line). In the right part), the frequency is large and exceeds the frequency threshold level Th for determining the exposure condition as indicated by the alternate long and short dash line, so it is necessary to change the exposure condition for both the bright part BR and the dark part DK. .
[0068]
Next, the exposure condition is changed for each of the bright part BR and the dark part DK, and pre-photographing is performed again to obtain luminance information.
[0069]
First, the dark portion DK is changed to an exposure condition that is 1 EV brighter than the initial exposure condition (+1 EV exposure condition, that is, the exposure time of 1/125 seconds in the above example). The luminance information as shown in FIG. 4 is acquired, and the corresponding luminance histogram is as shown in FIG. Although the exposure condition determination at this time is performed only for the dark part DK, in this example, since the frequency of the histogram of the dark part DK still exceeds the frequency threshold level Th, further change of the exposure condition is required. Therefore, the exposure condition is changed to an exposure condition that is brighter by 2 EV than the first exposure condition (+2 EV exposure condition, ie, exposure time 1/60 seconds in the above example), pre-photographing is performed again, and luminance information is acquired. The luminance information under the + 2EV exposure condition is as shown in FIG. 4G, for example, and the corresponding luminance histogram is as shown in FIG. 4H. As shown in the drawing, since the frequency of the histogram of the dark portion DK is smaller than the frequency threshold level Th, the exposure condition (exposure time 1/60 seconds) at this time is set as the main photographing condition. As a result, in the shooting scene as shown in FIG. 4, main shooting conditions are set so that a person is shot with proper exposure.
[0070]
On the other hand, the bright portion BR is changed to an exposure condition that is darker by 1 EV than the initial exposure condition (-1 EV exposure condition, that is, exposure time 1/500 seconds in the above example). Luminance information as shown in (E) is acquired, and the corresponding luminance histogram is as shown in FIG. Although the exposure condition determination at this time is performed only for the bright portion BR, in this example, since the frequency of the histogram of the bright portion BR still exceeds the frequency threshold level Th, as in the case of the dark portion DK described above, further It is required to change the exposure conditions. Therefore, the exposure condition is changed to an exposure condition that is darker by 2 EV than the first exposure condition (-2 EV exposure condition, that is, the exposure time of 1/1000 seconds in the above example), and pre-photographing is performed again to obtain luminance information. .
The luminance information under the −2EV exposure condition is as shown in FIG. 4I, for example, and the corresponding luminance histogram is as shown in FIG. 4J. As shown in the drawing, since the frequency of the histogram of the bright part BR is smaller than the frequency threshold level Th, the exposure condition (exposure time 1/1000 second) at this time is set as another main photographing condition. . As a result, in the photographing scene as shown in FIG. 4, main photographing conditions are set such that the background is appropriately exposed.
[0071]
As a result, when shooting a shooting scene as shown in FIG. 4 in the wide dynamic range shooting mode, exposure with shooting conditions of exposure time 1/60 seconds and exposure with shooting conditions of exposure time 1/1000 seconds. Are obtained in succession, and by acquiring both appropriate image information relating to the person and appropriate image information relating to the background, and subsequently combining these image information, It is possible to obtain a wide dynamic range image in which both the backgrounds are displayed in an appropriate exposure state.
[0072]
According to the first embodiment as described above, prior to performing the main shooting, information on the dynamic range of the shooting scene is acquired and analyzed, and the main shooting conditions are set based on the analysis result. Since shooting with multiple exposures or shooting with multiple exposures with different exposure conditions is possible, it is possible to automatically set exposure conditions suitable for the dynamic range of the shooting scene. It is possible to generate and reproduce an image adapted to the dynamic range of the shooting scene.
In particular, in the case of shooting with multiple exposures under different exposure conditions, even if the shooting scene has a wide dynamic range, shooting suitable for the scene can be performed and the dynamic range is substantially wide. An image can be generated and reproduced.
[0073]
5 to 7 show a second embodiment of the present invention, and FIG. 5 is a block diagram showing a detailed configuration of the shutter control information circuit 21. As shown in FIG. In the second embodiment, the names, reference numerals, etc. of the first embodiment described above are cited as necessary, and descriptions of the same parts as the first embodiment are omitted, and are mainly different. Only the point will be described.
[0074]
Similarly to the first embodiment described above, the second embodiment also applies the imaging device of the present invention to an electronic camera, and the configuration thereof is as shown in FIG.
[0075]
Further, the electronic camera according to the present embodiment also performs shutter control on the assumption that two exposures are performed under different exposure conditions when the wide dynamic range shooting mode is selected, as described above. .
[0076]
In the configuration shown in FIG. 5, the pre-shooting operation for acquiring the luminance information related to the shooting scene is performed, and the luminance information aa related to the shooting scene is output from the A / D converter 5, and thus the scene information distribution calculation is performed. The process until the luminance distribution information bb is output through the scene information distribution calculation circuit 41, which is an information acquisition unit configured similarly to the circuit 31, is the same as that shown in FIG. 2 of the first embodiment.
[0077]
In the subsequent scene information analysis circuit 42 as information analysis means, the luminance distribution information (histogram) bb is input from the scene information distribution calculation circuit 41 and the strobe setting information mm is input from the CPU 8 to analyze the histogram. That is, in the second embodiment, the strobe setting information mm is acquired to estimate the brightness range in which the main subject exists, and the subsequent processing is performed so that the main subject has proper exposure. It has become. At this time, the exposure condition is set so that proper exposure is performed only for the bright part when the main subject is present on the bright part side, and only for the dark part when the main subject is present on the dark part side.
[0078]
For example, when the strobe setting information mm indicates the content of “use strobe”, a photographing scene of “person photographing under backlight in the daytime” or “person photographing at night” is assumed. At this time, the luminance distribution information (histogram) bb obtained under the first exposure condition is referred to.
[0079]
As a result of referring to this luminance distribution information (histogram) bb, if the histogram frequency in the luminance portion indicating the bright portion (out-of-brightness) is larger than a predetermined value, it is assumed that there are many portions corresponding to over-exposure. It can be assumed that “photographing a person under backlight in the daytime” in the scene corresponds, and it can be estimated that the main subject is present in a relatively dark area in photography using a strobe. Therefore, the subsequent processing is performed so that the exposure conditions relating to the dark part where the main subject exists are appropriate.
[0080]
In addition, when the histogram frequency in the luminance portion indicating the bright portion (out-of-brightness) is equal to or less than a predetermined value, it is assumed that there are not many portions corresponding to over-exposure, and “night-time person shooting” in the assumed shooting scene. Therefore, it can be estimated that the main subject is present in a relatively bright area in photographing using a strobe. Therefore, the subsequent processing is performed so that the exposure conditions relating to the bright part where the main subject exists are appropriate.
[0081]
On the other hand, when the strobe setting information mm indicates the content of “do not use strobe”, the subsequent processing is performed so that the exposure condition regarding the dark portion is appropriate.
[0082]
Then, the scene information analysis circuit 42 calculates a histogram frequency or the like in the luminance part indicating the bright part or the dark part, and outputs information regarding the analysis result as the luminance analysis information nn.
[0083]
The exposure condition determination circuit 43, which is a photographing setting means and a control means, receives the luminance analysis information nn and performs the same processing as the exposure condition determination circuit 33 in the first embodiment described above.
[0084]
If the exposure condition determination result is “exposure condition change”, the exposure condition determination circuit 43 outputs the changed exposure information pp as the changed exposure condition information. The exposure condition changing circuit 44, which is a photographing setting means and a control means, inputs this changed exposure information pp, performs the same processing as the exposure condition changing circuit 34 in the first embodiment described above, and sets the changed exposure conditions. Corresponding pre-shoot shutter control information qq is output.
[0085]
On the other hand, if the determination result of the exposure condition is “determination of exposure condition”, the exposure condition determination circuit 43 outputs the main photographing exposure information oo as the exposure condition information in the main photographing, and an exposure ratio adjusting circuit 45 described later. Then, it is transmitted to the main photographing shutter control information generation circuit 46.
[0086]
An exposure ratio adjusting circuit 45, which is a photographing setting means and an adjusting means, inputs the main photographing exposure information oo and camera setting information rr such as photometric area information and strobe information output from the CPU 8, and performs different exposures. To calculate the exposure ratio when photographing twice.
[0087]
Here, the main photographing exposure information oo is information representing an appropriate exposure condition for the main subject, and unlike the first embodiment described above, is information relating to only one exposure. As an exposure condition for performing exposure on portions other than the main subject in the circuit 45, an exposure ratio with respect to the main photographing exposure information oo is calculated and output as exposure ratio information ss.
[0088]
A main photographing shutter control information generation circuit 46 as photographing setting means inputs the main photographing exposure information oo and the exposure ratio information ss, and generates shutter control information for main photographing for performing exposure twice with different exposure amounts. This is output as main photographing shutter control information tt.
[0089]
The shutter control information changeover switch 47 switches the switch based on the control information ii from the CPU 8 and outputs the pre-shooting shutter control information qq or the main shooting shutter control information tt as the shutter control information kk.
[0090]
The CPU 8 controls whether to perform the pre-photographing operation again or enter the main photographing standby state, as in the first embodiment described above, based on the determination result of the appropriate exposure information dd.
[0091]
FIG. 6 is a flowchart showing processing in the shutter control information circuit 21. Regarding the description of FIG. 6, the same steps as those of FIG. 3 described above are described, and detailed description thereof is omitted.
[0092]
Step S11 is the same as step S1 of FIG. 3 described above.
[0093]
Next, on the basis of the strobe setting information mm, a luminance part that makes the exposure condition appropriate with respect to the luminance information histogram calculated in step S11 is determined (step S12). Here, as described above, it is determined which of the bright part and the dark part is appropriate as the exposure condition.
[0094]
Subsequent steps S13 and S14 are substantially the same as steps S2 and S3 in FIG.
[0095]
Further, in step S14, steps S15, S16, and S17 related to the processing when it is determined that the frequency corresponding to the brightness of the bright part (dark part) is equal to or greater than a predetermined value (“exposure condition change”). This is the same as step S4, step S5, and step S6 in FIG.
[0096]
If it is determined in step S14 that the frequency corresponding to the brightness of the bright part (dark part) is less than a predetermined value (“determining exposure conditions”), the main photographing exposure information is based on the current exposure conditions. oo is generated and output (step S18).
[0097]
Next, an exposure ratio for performing multiple exposures with different exposure amounts is calculated based on the camera setting information rr (step S19).
[0098]
Here, as will be described in detail later, with reference to the camera setting information rr and the main photographing exposure information oo, the photographing exposure information relating to the luminance portion other than the main subject with respect to the main photographing exposure information oo for appropriately exposing the main subject. Is calculated and output as exposure ratio information ss.
[0099]
Next, based on the main photographing exposure information oo and the exposure ratio information ss, the main photographing shutter control information tt is generated and output to instruct the CPU 8 that the main photographing standby state has been entered (step S20).
[0100]
Thus, when the process of step S17 or step S20 is performed, this process is terminated.
[0101]
The processing flow of FIG. 6 in the second embodiment is basically the same as the processing flow of FIG. 3 in the first embodiment described above, but the analysis of the histogram under the first exposure condition (step S13). In this process, since only one of the bright part and the dark part is referred to, even when the pre-photographing operation is performed again thereafter, it is not necessary to refer to both the bright part and the dark part. .
[0102]
Further, in the process of FIG. 6 after performing the pre-photographing operation after changing the exposure condition, it is already known which of the bright part and the dark part is to be properly exposed, so that step S12 is not necessary. . Therefore, a flag indicating whether or not the exposure condition has been changed is set, and if the flag is set, the process of step S12 may be skipped.
[0103]
Next, FIG. 7 is a table showing an example of a look-up table used for calculating the exposure ratio information ss in the exposure ratio adjusting circuit 45.
[0104]
In order to calculate the exposure ratio information ss with reference to FIG. 7, “exposure time” in main subject appropriate exposure as main photographing exposure information oo, and “photometry level information”, “aperture value information” as camera setting information rr, And “strobe setting information mm” are used. Here, the electronic camera in this embodiment can set the exposure time in the range of 1/8000 second to 1/4 second, and can set the aperture value in the range of F2.8 to F11.0. Shall.
[0105]
The exposure ratio information ss shown in FIG. 7 is a ratio at the time of calculating the exposure time related to subjects other than the main subject with respect to the main photographing exposure information oo (exposure time related to the main subject). That is, the exposure time relating to subjects other than the main subject can be calculated by adding the corresponding ratio to the main photographing exposure information oo.
[0106]
Further, this ratio varies depending on whether the main photographing exposure information oo is information on a bright part or information on a dark part.
[0107]
For example, when the main photographing exposure information oo is information relating to a bright part, it is necessary to calculate exposure information relating to a dark part, which is a longer exposure time than a bright part. Therefore, the ratio indicating the exposure ratio is represented by 1 or more.
[0108]
On the other hand, when the main photographing exposure information oo is information related to the dark part, it is necessary to calculate the exposure information related to the bright part, which requires a shorter exposure time than the dark part. Therefore, the ratio indicating the exposure ratio is represented by 1 or less.
[0109]
These bright portions and dark portions are shown in the column of “main subject” in each column shown in the first row of FIG. 7, and “bright portion” indicates that the main photographing exposure information oo relates to the bright portion. “Dark part” represents the exposure ratio calculated when the main photographing exposure information oo relates to the dark part. However, since the range of the exposure time that can be set by the electronic camera is limited as described above, an exposure ratio that can realize the exposure time within the range is set.
[0110]
Next, each information included in the camera setting information rr used in FIG. 7 and its handling will be described.
[0111]
The photometric level information is information relating to the dynamic range of the photographic scene obtained for each area by dividing the screen into a plurality of areas. Here, the difference between the maximum value and the minimum value for the photometric level obtained from each area is obtained, the ratio of the difference to the maximum value of the photometric level range is obtained, and exposure is performed according to the ratio. The ratio is calculated from the look-up table in FIG.
[0112]
In the example shown in FIG. 7, the ratio of the photometric level difference to the maximum range value is classified into five, and the corresponding exposure ratio is calculated depending on whether the main photographing exposure information oo relates to the bright part or the dark part. . Specifically, if the ratio is “50% or more”, the exposure ratio is, for example, “16” (16 if the main exposure information oo is bright, 1/16 if dark), and so on) Similarly, “25” to “50%” is “8”, “10 to 25%” is “4”, “5 to 10%” is “2”, and “less than 5%”. Set to “1”. When the ratio is “1”, since the exposure time is equal to the main shooting exposure information oo, shooting is performed by one shooting operation even in the wide dynamic range shooting mode.
[0113]
Next, the aperture value information is information representing the aperture value (F number) in the imaging optical system including the lens 2 and the aperture / shutter mechanism 3. Here, the exposure ratio is calculated from the look-up table shown in FIG. 7 based on the aperture value information itself obtained from the imaging optical system.
[0114]
In the example shown in FIG. 7, the corresponding exposure ratio is calculated by the same means as in the case of the photometric level described above for the aperture value information. Specifically, if the aperture value information is “2.8”, the exposure ratio is, for example, “16”, and similarly, “4.0” is “8”, and “5.6”. If it is “4” or “8.0”, it is “2”, and if it is “11.0”, it is “1”.
[0115]
Further, as described above, the strobe setting information mm is information regarding whether or not the strobe 19 is used, and the exposure ratio is calculated from the look-up table shown in FIG. 7 based on this information.
[0116]
In this example, specifically, when the strobe is used (“used”), the exposure ratio is set to “4”, for example, and when the strobe is not used (“not used”), the exposure ratio is set to “8”. To do.
[0117]
In addition, FIG. 7 shows a case where the exposure ratio is calculated using the main photographing exposure information oo.
[0118]
Here, the exposure ratio is calculated from the look-up table shown in FIG. 7 depending on whether the luminance part to be photographed by the main photographing exposure information oo relates to the bright part or the dark part. Yes.
[0119]
In this example, specifically, when the main photographing exposure information oo is information relating to a bright part (short-time exposure in the wide dynamic range photographing mode), the exposure ratio is set to “4”, for example, and information relating to a dark part (wide dynamic range). In the case of long exposure in the photographing mode, “8” is set.
[0120]
Here, the case where various types of information are used has been described. However, when actually calculating the exposure ratio, for example, the exposure ratio may be calculated from any one of the information, or the average of the exposure ratios for all information may be calculated. Alternatively, the exposure ratio may be calculated by weighted average by weighting the importance of each information, and the present invention is not limited to this and can be realized by various means. is there.
[0121]
According to the second embodiment as described above, prior to performing the main shooting, information on the dynamic range of the shooting scene is acquired and analyzed, and the main shooting conditions are set based on the analysis result. Since shooting by multiple exposures or shooting by multiple exposures under different exposure conditions is performed, the same effects as those of the first embodiment described above can be achieved. In particular, in the case of shooting with multiple exposures under different exposure conditions, the exposure ratio is adjusted so that shooting suitable for the scene is performed even if the shooting scene has a wide dynamic range. And an image having a substantially wide dynamic range can be generated and reproduced.
[0122]
In addition, this invention is not limited to embodiment mentioned above, Of course, a various deformation | transformation and application are possible within the range which does not deviate from the main point of invention.
[0123]
【The invention's effect】
As described above, according to the imaging apparatus of the first aspect of the present invention, since the main shooting is performed after the information related to the dynamic range of the shooting scene is acquired and analyzed to set the main shooting conditions, the shooting scene is changed. Shooting can be performed by automatically setting exposure conditions suitable for the dynamic range that can be obtained, and as a result, an image adapted to the dynamic range of the shooting scene can be reproduced.
[0124]
According to the image pickup apparatus of the present invention of claim 2, the same effect as that of the invention of claim 1 is obtained, and the exposure condition before the main shooting and the main shooting condition are related to a plurality of exposure amounts by different exposures. Since the information is set, it is possible to perform multiple exposures with different exposures even when the dynamic range of the shooting scene is wide, and it is possible to perform shooting suitable for the dynamic range of the shooting scene.
[0125]
Furthermore, according to the image pickup apparatus of the present invention according to claim 3, information relating to the dynamic range of the shooting scene is acquired and analyzed before the main shooting to set the main shooting conditions, and then multiple exposures are performed under different exposure conditions in the main shooting. Therefore, even when the dynamic range of the shooting scene is wide, shooting can be performed by automatically setting different exposure conditions necessary for multiple exposures so as to adapt to it. As a result, it is possible to reproduce an image adapted to the dynamic range of the shooting scene.
[0126]
According to the imaging apparatus of the present invention according to claim 4, the same effect as that of the invention according to claim 1 or claim 3 is obtained, and whether or not the exposure condition is appropriate is determined and determined to be inappropriate. In this case, since the exposure condition is changed and the information is acquired again, it is possible to adaptively determine the exposure condition suitable for the shooting scene and perform shooting.
[0127]
According to the imaging device of the present invention of claim 5, the same effect as that of the invention of claim 4 is achieved, and when changing the exposure condition, the exposure condition is darker than the current exposure condition or the current exposure condition. Since either one or both of the bright exposure conditions are changed, the exposure conditions can be changed to match the dynamic range of the shooting scene.
[0128]
According to the imaging device of the present invention according to claim 6, the same effect as the invention according to claim 1 or claim 3 is achieved, and the adjusting means is adapted to the imaging condition obtained from the analysis result of the information analyzing means. Since the adjustment is further performed, shooting suitable for the dynamic range of the shooting scene can be performed under the main shooting conditions that can reproduce the image more appropriately.
[0129]
According to the image pickup apparatus of the present invention according to claim 7, the same effect as the invention of claim 2 or claim 3 is obtained, and a plurality of adjustment means are provided under different exposure conditions obtained from the analysis result of the information analysis means. Since the ratio of the different exposure conditions is adjusted in the main shooting conditions for performing multiple exposures, the shooting conditions of the shooting scene with the ratio of the different exposure conditions that can reproduce the image more appropriately are adjusted. Photography suitable for the dynamic range can be performed.
[0130]
According to the image pickup apparatus of the present invention according to claim 8, the same effect as the invention according to claim 6 or claim 7 is achieved, and the dynamic range of the photographic scene obtained by the adjusting means as the analysis result of the information analyzing means Since the main shooting conditions are adjusted according to the conditions, it is possible to set the main shooting conditions so that the image of the shooting scene can be reproduced more appropriately.
[0131]
According to the image pickup apparatus of the present invention according to claim 9, the same effect as the invention of claim 6 or claim 7 is achieved, and the adjusting means is configured to set the main photographing condition obtained from the analysis result of the information analysis means. With reference to this, since the main shooting condition is adjusted when it is determined that adjustment is necessary, the image of the shooting scene can be set to a main shooting condition that can be reproduced more appropriately.
[0132]
According to the imaging device of the present invention of claim 10, the same effect as that of the invention of claim 9 is achieved, and the imaging condition referred to in the adjusting means is at least of information relating to exposure amount and aperture information. Since one of them is included, it is possible to set the photographing conditions so that the image of the photographing scene can be reproduced more appropriately.
[0133]
According to the imaging device of the present invention according to claim 11, the effect similar to that of the invention according to claim 6 or claim 7 is achieved, and the adjusting means uses flash light emitting means for irradiating light toward the object to be photographed. Since the main shooting conditions are adjusted according to the situation, it is possible to set the main shooting conditions so that the image of the shooting scene can be reproduced more appropriately.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a basic configuration of an electronic camera according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a detailed configuration of a shutter control information circuit in the first embodiment.
FIG. 3 is a flowchart showing processing in the shutter control information circuit of the first embodiment.
FIG. 4 is a diagram showing an image of processing performed in the shutter control information circuit of the first embodiment.
FIG. 5 is a block diagram showing a detailed configuration of a shutter control information circuit according to a second embodiment of the present invention.
FIG. 6 is a flowchart showing processing in the shutter control information circuit of the second embodiment.
FIG. 7 is a table showing an example of a lookup table used for calculating exposure ratio information ss in the exposure ratio adjusting circuit according to the second embodiment.
FIG. 8 is a diagram showing a state in which a subject having a luminance difference is exposed multiple times with different exposure amounts in the related art.
[Explanation of symbols]
1 ... Image sensor (photographing means)
5 ... A / D converter
7… AF, AE, AWB detection circuit
8 ... CPU
19 ... Strobe (flash emission means)
21. Shutter control information circuit
22 ... Switch
31, 41... Scene information distribution calculation circuit (information acquisition means)
32, 42 ... Scene information analysis circuit (information analysis means)
33, 43 ... Exposure condition discrimination circuit (imaging setting means, control means)
34, 44 ... Exposure condition changing circuit (imaging setting means, control means)
35, 46 ... Real shooting shutter control information generation circuit (shooting setting means)
36, 47 ... Shutter control information switch
45. Exposure ratio adjustment circuit (imaging setting means, adjustment means)

Claims (8)

Prior to performing the main shooting, information acquisition means for acquiring information on the dynamic range of the shooting scene based on information on a plurality of exposure amounts by different set exposures ;
Information analysis means for analyzing information on the dynamic range of the shooting scene acquired by the information acquisition means;
Shooting setting means for setting conditions relating to a plurality of exposure amounts due to different exposures in the main shooting based on the result analyzed by the information analysis means;
Photographing means for performing main photographing in accordance with conditions relating to a plurality of exposure amounts due to different exposures in the main photographing set by the photographing setting means;
An imaging apparatus comprising: The imaging setting unit determines whether or not the exposure condition when the information is acquired by the information acquisition unit is appropriate from the analysis result of the information analysis unit. The imaging apparatus according to claim 1 , further comprising a control unit configured to control the information to be acquired again by the information acquisition unit after changing the conditions. The control means, when changing the exposure condition determined to be inappropriate from the analysis result of the information analysis means, either the exposure condition darker than the current exposure condition or the exposure condition brighter than the current exposure condition, The imaging apparatus according to claim 2 , wherein the imaging apparatus is changed to both. The photographing setting means includes adjusting means for adjusting the ratio of the different exposure conditions in the main photographing conditions in which exposure is performed a plurality of times under different exposure conditions obtained from the analysis result of the information analysis means. The imaging device according to claim 1 . 5. The imaging apparatus according to claim 4 , wherein the adjusting unit adjusts the main photographing condition according to a dynamic range of a photographing scene obtained as an analysis result of the information analyzing unit. Said adjustment means according to claim 4, characterized in that one which regulates the shooting condition when referring to the imaging condition obtained from the analysis result of the information analysis unit, adjustment is deemed necessary The imaging device described in 1. The imaging apparatus according to claim 6 , wherein the main photographing condition referred to in the adjusting unit includes at least one of information relating to an exposure amount and aperture information. It further comprises flash light emitting means for irradiating light toward the object to be photographed,
5. The image pickup apparatus according to claim 4 , wherein the adjusting unit adjusts the main photographing condition in accordance with a use situation of the flash light emitting unit.

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