JP4479843B2 - Imaging apparatus and exposure control method - Google Patents

Description

  The present invention relates to an imaging apparatus and an exposure control method. Specifically, when a presentation image presented by the presentation device is detected from the captured image, a detection region is set at a position different from the detected presentation image. By performing exposure control according to the detection value calculated from the image signal in the detection region, it is possible to obtain a captured image in which the presented image has an appropriate brightness.

  The conventional imaging apparatus performs brightness detection with a large weight on the center of the imaging range, assuming that a desired subject is at the center of the imaging range. For this reason, when the desired subject is at the center of the imaging range, the imaging device can obtain a captured image in which the desired subject is controlled to an optimal brightness.

  However, when brightness detection is performed with a large weight at the center of the imaging range, when the desired subject deviates from the center of the imaging range, a captured image in which the desired subject is controlled to the optimum brightness is obtained. The case where it cannot be obtained will arise.

  As described above, the phenomenon that the desired subject is not controlled to the optimum brightness is caused by photographing a presentation image presented by the presentation device, for example, an image displayed on the television device or an image projected on the screen by the projector. It is a problem that sometimes occurs.

  FIG. 20 shows a case where, for example, a presentation is imaged by the imaging apparatus. In this case, as shown in FIG. 20A, the composition of the captured image is often set so that the presentation image projected on the screen and the presenter are included in the imaging range, and the screen is not necessarily in the imaging range. It is not necessarily the center of Here, when the screen is not at the center of the imaging range, the imaging device performs brightness control so that the subject located at the center of the imaging range has appropriate brightness, unlike the presented image projected on the screen. . For this reason, as shown in FIG. 20B, the captured image may be an image in which the projected presentation image is overexposed.

  Further, when brightness detection is performed with a large weight at the center of the imaging range, a captured image in which the desired subject is controlled to the optimum brightness is obtained even if the desired subject is the center of the imaging range. The case where it cannot be obtained will arise. As described above, the phenomenon that the desired subject is not controlled to the optimum brightness may occur even when the desired subject is based on a low-luminance color such as black or dark blue. For example, materials used in presentations and the like vary in design depending on the presenter, and materials with designs based on blue or black are often projected. FIG. 21 illustrates a case where a presentation image projected onto a screen, for example, is captured by the imaging apparatus. Here, as shown in FIG. 21A, when the presented image is an image based on a low-luminance color such as black, the imaging device performs brightness control so that a dark image becomes bright. Done. For this reason, as shown in FIG. 21B, in the captured image, dark portions such as black in the presented image are lifted, and bright portions such as white characters and pictures in the presented image are too bright, and white In some cases, a skipped image results.

  In addition, when the presented image is dark, strobe light emission may be performed so that the presented image can be captured with appropriate brightness. However, when the strobe light is reflected and enters the imaging device, it becomes impossible to obtain a captured image in which the presented image has an appropriate brightness due to the influence of the reflected light.

  FIG. 22 shows a case where a presentation image displayed on a screen of a television device, for example, is captured by the imaging device. Here, as shown in FIG. 22A, when the presented image is a dark image such as black, strobe light emission is performed so that the presented image has an appropriate brightness. When the strobe light is reflected on the display screen of the television device, the captured image is a reflection of the reflected strobe light as shown in FIG. 22B, making it difficult to read the contents of the presented image. It may become.

  In addition, when the design of the presentation image changes dynamically due to a moving image or a slide show, the imaging apparatus performs brightness control following the change of the scene. Therefore, the captured image is very difficult to see due to brightness fluctuations and the like.

  For this reason, the imaging apparatus of Patent Document 1 is provided with a presentation imaging mode that can reliably capture a presentation material, and in the presentation imaging mode, strobe light emission is limited.

JP 2007-195029 A

  By the way, even when strobe light emission is limited as a presentation imaging mode, when a desired subject is based on a low-luminance color such as black or dark blue, a dark portion in a presentation image is lifted as described above. For this reason, bright portions such as white characters and pictures in the presented image may become too bright, resulting in an overexposed image.

  Further, when the presented image has a desired brightness, if the user fixes brightness control in the imaging device, a captured image in which the presented image has an appropriate brightness can be obtained. However, when the illumination state changes during imaging, the user must reset the brightness control each time the illumination state changes. Furthermore, since the user cannot accurately predict under what kind of illumination, it is difficult to fix the brightness control in an optimum state.

  Therefore, the present invention provides an imaging device and an exposure control method that can easily obtain a captured image in which the presented image has an optimal brightness when an image presented by the presentation device is captured. is there.

  The concept of the present invention is to detect a presentation image presented by a presentation device from an imaging device, for example, an image projected on a screen by a projector or an image displayed on a screen of a television device, and detect the presentation image. Sometimes the detection area is switched, and exposure control is performed so that a captured image in which the presented image has an optimum brightness can be obtained.

  An imaging apparatus according to a first aspect of the present invention includes an imaging unit that captures an image of a subject and obtains an image signal, and a detection region is set for a captured image based on the image signal obtained by the imaging unit, and an image signal in the detection region Based on the difference in luminance in the captured image, a detection unit that calculates a detection value from the exposure unit, an exposure adjustment unit that performs exposure adjustment, a control unit that controls the exposure adjustment unit so that the detection value becomes a predetermined value, A presentation image detection unit for detecting a presentation image presented by the image presentation device, and when the presentation image detection unit detects the presentation image, the detection unit sets a detection region at a position different from the detected presentation image. To do.

  The exposure control method according to the first aspect of the invention includes an imaging step of capturing an image of a subject by an imaging unit to obtain an image signal, and setting a detection region for the captured image based on the obtained image signal, A detection step of calculating a detection value from the image signal, a presentation image detection step of detecting a presentation image presented by the image presentation device from the captured image based on a difference in luminance in the captured image, and a detection value of a predetermined value An exposure adjustment step for adjusting exposure as a value, and when a presentation image is detected in the presentation image detection step, a detection region is set in a position different from the detected presentation image in the detection step.

  In the first invention, when a presentation image is detected from a captured image, a detection region is provided at a position different from the detected presentation image. Further, as a detection of the presented image, it is detected whether or not the captured image is included in the captured image, and when it is detected that the captured image is included in the captured image, detection is performed on at least one side of the captured image. An area is provided. When an image signal is generated in which the captured image has a horizontally long aspect ratio rather than the aspect ratio of the presented image, the detection region is provided in a region that is not the presented image generated in the captured image due to a difference in aspect ratio. In addition, when an imaging mode selection operation for capturing a presentation image is performed, a detection region is provided on at least one side of the captured image. A detection value is calculated from the image signal in the detection region set in this way, and exposure adjustment is performed so that the calculated detection value becomes a predetermined value. For example, at least one of the amount of light incident on the imaging unit, the image gain output from the imaging unit, and the exposure time when an image signal is obtained by the imaging unit is adjusted so that the calculated detection value becomes a predetermined value.

  An image pickup apparatus according to a second aspect of the present invention includes an image pickup unit that picks up an image of a subject and obtains an image signal, and sets a detection region for a picked-up image based on the image signal obtained by the image pickup unit. A detection unit that calculates a detection value from the image, an exposure adjustment unit that performs exposure adjustment, a control unit that controls the exposure adjustment unit so that the detection value becomes a predetermined value, and imaging of the presentation image presented by the image presentation device. In the presentation image capturing mode to be performed, the detection unit provides the detection region on at least one side excluding the central portion of the captured image.

  The exposure control method according to the second invention includes an imaging step of capturing an image of a subject by an imaging unit to obtain an image signal, and setting a detection region for the captured image based on the obtained image signal, A detection step for calculating a detection value from the image signal, an exposure adjustment step for performing exposure adjustment using the detection value as a predetermined value, and a presentation image imaging mode for imaging a presentation image presented by the image presentation device A mode selection step, and when the presentation image capturing mode is selected in the mode selection step, the detection step provides the detection region on at least one side excluding the central portion of the captured image.

  In 2nd invention, it has the presentation image imaging mode which images the presentation image shown by the image presentation apparatus. For example, when an operation signal from a user interface unit that generates an operation signal according to a user operation indicates a selection operation of the presentation image imaging mode, the detection unit provides a detection region on at least one side of the captured image. Thereby, brightness control can be performed without being influenced by the presented image even when the presented image is not detected by the detection unit.

  According to the first invention, when the presentation image is detected from the captured image, the detection area is provided at a position different from the detected presentation image, and the detection value calculated from the image signal of the detection area is obtained. Exposure adjustment is performed based on this. For this reason, when exposure control is performed, the influence of the presented image is reduced, and a captured image in which the presented image has an optimum brightness can be obtained.

  According to the second invention, in the presentation image imaging mode in which the presentation image presented by the image presentation device is captured, the detection unit sets the detection region on at least one side excluding the central portion of the captured image. Provide. For this reason, when exposure control is performed, the influence of the presented image is reduced, and a captured image in which the presented image has an optimum brightness can be obtained. Furthermore, brightness control can be performed without being affected by the presented image even when the presented image is not detected by the detection unit.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The description will be given in the following order.
1. First embodiment (control for automatically switching to the presentation image capturing mode)
2. Second embodiment (control to switch to the presentation image capturing mode by user operation)

<1. First Embodiment>
[Automatic switching of presentation image capture mode]
FIG. 1 shows the configuration of the imaging apparatus. The subject light is incident on the imaging element 211 of the imaging unit 21, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor via the lens unit 11 and the aperture mechanism 12.

  The imaging element 211 converts the imaging light of the subject image formed on the light receiving surface into an electrical signal for each pixel to generate an image signal of three primary colors. Further, the generated image signal is supplied to a CDS (Correlated Double Sampling circuit) unit 212.

  The CDS unit 212 removes noise from the image signal supplied from the image sensor 211 and supplies the image signal after the noise removal to the amplification unit 213. The amplification unit 213 adjusts the gain of the image signal supplied from the CDS unit 212 and supplies the image signal Sa after gain adjustment to the A / D (Analog / Digital) conversion unit 23.

  The timing signal generator 22 generates a drive signal TD for generating an image signal by the image sensor 211 and supplies the drive signal TD to the image sensor 211. The timing signal generation unit 22 controls the exposure time (effective charge accumulation time obtained by photoelectric conversion) in the image sensor 211 by the drive signal TD.

  The A / D converter 23 converts the analog image signal Sa into a digital image signal DVa and supplies the digital image signal DVa to the presentation image detector 31, the detector 32, and the image processor 35.

  The presentation image detection unit 31 performs a process of detecting a presentation image from a captured image based on the image signal DVa, generates a detection signal JA indicating a detection result, and supplies the detection signal JA to the control unit 51.

  FIG. 2 shows the configuration of the presentation image detection unit 31. The conversion processing unit 311 of the presentation image detection unit 31 converts the image signal DVa of the three primary colors into a luminance signal DY and a color difference signal DC, the luminance signal DY is converted into a binarization processing unit 312, and the color difference signal DC is converted into a binarization processing unit. 313.

  The binarization processing unit 312 performs processing for binarizing the luminance signal DY, and supplies the obtained luminance binarized signal BY to the signal selection unit 314. In addition, the binarization processing unit 313 performs processing for binarizing the color difference signal DC and supplies the obtained color difference binarized signal BC to the signal selection unit 314. The binarization processing unit 312 binarizes the luminance signal DY by comparing the luminance signal DY with a threshold value, and generates a luminance binarized signal BY. The binarization processing unit 313 binarizes the color difference signal DC by comparing the color difference signal DC with a threshold value, and generates a color difference binarized signal BC. In addition, the binarization processing units 312 and 313 may set the threshold to a fixed level in advance, and set the threshold according to the captured image so that the presented image can be detected from the captured image with high accuracy. It may be a thing.

  The signal selection unit 314 selects the luminance binarized signal BY or the color difference binarized signal BC, and supplies the selected binarized signal to the horizontal distribution acquisition unit 315 and the vertical distribution acquisition unit 316.

  When the binarized signal is the luminance binarized signal BY, the horizontal distribution acquisition unit 315 counts pixels in which the signal level of the luminance binarized signal BY is higher than a threshold value for each line, thereby calculating the horizontal distribution. Then, a horizontal distribution signal DSh indicating this distribution is supplied to the detection processing unit 317. In addition, when the binarized signal is the color difference binarized signal BC, the horizontal distribution acquisition unit 315 counts pixels in which the signal level of the color difference binarized signal BC is higher than a threshold value for each line. A distribution is obtained, and a horizontal distribution signal DSh indicating this distribution is supplied to the detection processing unit 317.

  When the binarized signal is the luminance binarized signal BY, the vertical distribution acquisition unit 316 counts pixels in which the signal level of the luminance binarized signal BY is higher than the threshold value in the vertical direction. Then, the vertical distribution acquisition unit 316 obtains a distribution in the vertical direction orthogonal to the above-described horizontal direction, and supplies a vertical distribution signal DSv indicating this distribution to the detection processing unit 317. Further, when the binarized signal is the color difference binarized signal BC, the vertical distribution acquisition unit 316 obtains a vertical distribution by counting pixels whose signal level of the color difference binarized signal BC is higher than a threshold value. The vertical distribution signal DSv indicating this distribution is supplied to the detection processing unit 317.

  The detection processing unit 317 detects the upper side and the lower side based on the horizontal distribution signal DSh supplied from the horizontal distribution acquisition unit 315, and detects the left side and the right side based on the vertical distribution signal DSv supplied from the vertical distribution acquisition unit 316. Perform the process. Further, when the detection processing unit 317 determines that the detected upper side, lower side, left side, and right side correspond to each side of the presented image, the image surrounded by the detected upper side, lower side, left side, and right side Is determined as a presentation image. Then, the detection processing unit 317 generates a detection signal JA indicating that the position of the presentation image or the presentation image has been detected, and supplies the detection signal JA to the control unit 51.

  Further, the detection processing unit 317 controls the signal selection operation of the signal selection unit 314 by the control signal CN, and first selects the luminance binarized signal BY. When the detected image cannot be detected from the luminance binarized signal BY, the detection processing unit 317 causes the signal selection unit 314 to select the color difference binarized signal BC, thereby not only the luminance binarized signal BY but also the color difference binary. The process which detects a presentation image from the digitization signal BC is performed.

  The detection unit 32 generates a detection signal JB indicating the brightness of the captured image from the supplied image signal DVa and supplies the detection signal JB to the control unit 51. For example, the detection unit 32 divides the captured image into m × n blocks, and calculates the sum of signals indicating the brightness of each pixel in each block. Further, the detection unit 32 weights the calculated sum for each block, and supplies the detection signal JB indicating the detection value to the control unit 51 using the addition value of the weighted sum as a detection value. Further, the detection unit 32 changes the detection region based on the control signal CTe from the control unit 51. That is, a block with a weight of “0” is not used for calculation of a detection value, and a block with a high weight has a higher contribution to the detection value. Therefore, the detection area is changed by switching the weighting.

  FIG. 3 shows the configuration of the detection unit 32. The block processing unit 321 of the detection unit 32 performs processing for dividing the captured image into m × n blocks, and supplies the image signal DVa to the block-by-block luminance calculation unit 322 as the image signal DBV for each block.

  The block-by-block luminance calculation unit 322 generates a block-by-block luminance value signal BT in which the luminance of each pixel in the block is totaled based on the image signal DBV and supplies the block-by-block luminance value signal BT to the multiplier 324.

  The weighting factor setting unit 323 sets a weighting factor W for each of the blocks based on the control signal CTe supplied from the control unit 51 and supplies the set weighting factor W to the multiplier 324.

  The multiplier 324 multiplies the block-by-block luminance value signal BT supplied from the block-by-block luminance calculation unit 322 by the weighting factor W set by the weighting factor setting unit 323 and supplies the result to the detection value calculation unit 325.

  The detection value calculation unit 325 adds the multiplication result of the block-specific luminance value signal BT and the weighting coefficient W in the captured image, and supplies the addition result to the control unit 51 as the detection signal JB. The detection value calculation unit 325 generates a detection signal JB for each captured image.

  The image processing unit 35 performs various image processing, such as white balance adjustment and gamma correction, on the image signal DVa supplied from the A / D conversion unit 23. Further, the image processing unit 35 converts, for example, an image signal of three primary colors subjected to white balance adjustment, gamma correction, and the like into an image signal such as a luminance signal or a color difference signal according to an image encoding technique of a still image or a moving image. The compression / decompression process is performed. The image processing unit 35 outputs the obtained still image or moving image compression-encoded signal GDa to the recording / reproducing unit 37. Furthermore, a process of outputting an image signal and / or a compression-coded signal of a still image or a moving image that has not been subjected to compression / decompression processing to an external device (not shown) is performed. When the compressed encoded signal GDb is supplied from the recording / reproducing unit 37, the image processing unit 35 performs processing to return the compressed encoded signal GDb to the image signal before the compression encoding process. Further, the image processing unit 35 generates a display image signal HG from the image signal DVa and supplies it to the display unit 38. The image processing unit 35 also generates a display image signal HG in which information indicating that the presentation image capturing mode is set is displayed on the screen based on the display signal HE supplied from the control unit 51. .

  The recording / reproducing unit 37 records the compressed encoded signal GDa supplied from the image processing unit 35 on a recording medium such as a semiconductor memory, an optical disk, or a magnetic tape. Further, the compressed encoded signal GDb recorded on the recording medium is read and supplied to the image processing unit 35.

  The display unit 38 is configured using, for example, a liquid crystal display element or the like, and performs image display based on the display image signal HG supplied from the image processing unit 35.

  The lens driving unit 41 drives a focus lens (not shown) of the lens unit 11 so that the subject image is focused on the light receiving surface of the image sensor 211. Further, the zoom lens (not shown) of the lens unit 11 is driven so that the size of the subject image formed on the light receiving surface of the image sensor 211 becomes a desired size.

The aperture driving unit 42 drives the aperture mechanism 12 to adjust the amount of light of the subject image formed on the light receiving surface of the image sensor 211.
The strobe 45 emits strobe light so that a captured image with a desired brightness can be obtained.

  A user interface unit 52 is connected to the control unit 51. The user interface unit 52 includes an operation key and an interface for inputting a remote operation signal from the outside. The user interface unit 52 generates an operation signal PS corresponding to a user operation and supplies the operation signal PS to the control unit 51.

  The control unit 51 includes a CPU (Central Processing Unit) 511, a ROM (Read Only Memory) 512, a RAM (Random Access Memory) 513, and the like. The CPU 511 executes a program stored in the ROM 512, generates a control signal corresponding to the operation signal PS, and supplies the control signal to each unit so that the operation of the imaging device 10A becomes an operation according to a user operation. Control. The RAM is used as a working area for temporarily storing information when performing various controls.

  Further, the control unit 51 generates a control signal so that the detection value indicated by the detection signal JB supplied from the detection unit 32 becomes a preset reference value, and supplies the control signal to the exposure adjustment unit. A desired subject in the captured image is set to an optimal brightness. The exposure adjustment unit adjusts at least one of the amount of light incident on the imaging unit 21, the gain of the image signal Sa output from the imaging unit 21, and the exposure time when the imaging unit 21 obtains the image signal Sa. The aperture mechanism 12, the aperture drive unit 42, the timing signal generation unit 22, and the amplification unit 213 correspond to an exposure adjustment unit. For example, the control unit 51 generates a control signal CTb based on the detection signal JB and supplies the control signal CTb to the aperture driving unit 42, so that the amount of light incident on the imaging unit 21 so that a desired subject in the captured image has optimum brightness. Adjust. In addition, the control unit 51 generates a control signal CTc based on the detection signal JB and supplies the control signal CTc to the timing signal generation unit 22, thereby adjusting the exposure time so that a desired subject in the captured image has optimum brightness. In addition, the control unit 51 generates the control signal CTd based on the detection signal JB and supplies the control signal CTd to the amplification unit 213, thereby adjusting the gain of the image signal Sa so that a desired subject in the captured image has an optimal brightness. .

  Furthermore, when the control unit 51 determines that the presentation image has been detected based on the detection signal JA supplied from the presentation image detection unit 31, the control unit 51 switches to the imaging mode in which the presentation image in the captured image has the optimum brightness. Further, the control unit 51 supplies a control signal CTe to the detection unit 32 and switches the operation of the detection unit 32 according to the imaging mode.

  The control unit 51 generates a control signal CTa and supplies the control signal CTa to the lens driving unit 41 to drive the focus lens so that the subject image is focused on the light receiving surface of the image sensor 211. Causes processing to be performed. The control unit 51 also generates a control signal CTh and supplies it to the strobe 45 to control strobe light emission.

  Next, the operation of the imaging device 10A will be described. FIG. 4 is a flowchart showing an exposure control operation in the imaging apparatus 10A. In step ST <b> 1, the control unit 51 causes the presentation image detection unit 31 to perform presentation image detection.

  FIG. 5 is a flowchart showing the presentation image detection operation. In step ST101, the presentation image detection unit 31 performs a conversion process. The presentation image detection unit 31 generates a luminance signal DY and a color difference signal DC from the three primary color image signals DVa, and proceeds to step ST102.

  In step ST102, the presentation image detection unit 31 performs binarization processing. The presented image detection unit 31 binarizes the luminance signal DY and the color difference signal DC, generates a luminance binarized signal and a color difference binarized signal, and proceeds to step ST103.

  In the binarization process, as described above, the luminance signal DY and the color difference signal DC are binarized by comparing the luminance signal DY and the color difference signal DC with the threshold value, and the luminance binarized signal BY and the color difference binarization are performed. A signal BC is generated. The threshold used for the binarization process may be set at a fixed level in advance, or may be set according to the captured image so that the presented image can be detected from the captured image with high accuracy.

  Here, when setting a threshold value according to a captured image, for example, the threshold value is set using a statistical method. As a statistical method, a mode method, a discriminant analysis method, or the like is used. In the mode method, the brightness level histogram of the captured image has bimodality, and when the portion of the presented image is separated from the portion of another image (hereinafter referred to as “background image”), the valley position is set as a threshold value. It is a method to set as. The discriminant analysis method is a method in which the histogram is divided into two groups according to the luminance level, and the division level that maximizes the variance between the groups is set as a threshold value.

  In step ST103, the presented image detection unit 31 selects the luminance binarized signal BY and proceeds to step ST104.

  In step ST104, the presentation image detection unit 31 acquires a horizontal distribution and proceeds to step ST105. In step ST105, the presentation image detection unit 31 acquires the vertical distribution and proceeds to step ST106.

  FIG. 6 shows a process for acquiring a horizontal distribution and a vertical distribution. 6A shows a captured image, and FIG. 6B shows a captured image after binarization processing. The presentation image detection unit 31 obtains a horizontal distribution shown in FIG. 6C by counting pixels in which the signal level of the luminance signal DY is higher than the threshold value for each line. Further, by counting pixels in which the signal level of the luminance signal DY is higher than the threshold value in the vertical direction, as shown in FIG. 6D, a distribution in the vertical direction perpendicular to the horizontal direction is obtained.

  In step ST <b> 106, the presented image detection unit 31 performs processing for detecting the upper side and the lower side of the presented image, and proceeds to step ST <b> 107.

  7 and 8 show the detection processing of the upper side and the lower side of the presented image. FIG. 7A shows a captured image after binarization processing, and FIG. 7B shows the horizontal distribution acquired in step ST104. Here, the presentation image detection unit 31 divides the horizontal distribution into a plurality of regions, and obtains the sum of target pixels for each region. For example, the region is divided into regions REh1, REh2, REh3, REh4, and REh5, and the sum of target pixels is obtained for each region. Next, the presented image detection unit 31 sequentially selects areas from the upper end to the lower end of the captured image, compares the sum of the target pixels in the selected area with a threshold value, and detects an area where the sum exceeds the threshold value. By performing such processing, it is possible to detect a region including the upper side of the presented image. Similarly, the presented image detection unit 31 sequentially selects areas from the lower end to the upper end of the captured image, compares the sum of the target pixels in the selected area with the threshold, and detects an area where the sum exceeds the threshold. By performing such processing, it is possible to detect a region including the lower side of the presented image.

  By the way, when the side of the presentation image is close to the boundary of the region, the sum of the target pixels in the region is greatly different, and it may be difficult to detect the region including the side of the presentation image. For example, if the upper side of the presentation image is in the region REh (n) and close to the region REh (n + 1), the sum of the target pixels in the region does not become a large value. Here, if a region where the sum exceeds the threshold value is detected, there is a possibility that the upper side of the presented image is erroneously determined to be included in the region REh (n + 1). Therefore, when the horizontal distribution is divided into a plurality of regions, the regions are provided so as to have portions overlapping with other regions. For example, regions are provided as shown in regions REh1 to REh5 and REh1s to REh4s. In this case, even if the upper side of the presented image is near the boundary between the region REh1 and the region REh2, and the position is in either the region REh1 or the region REh2, the total sum of the target pixels in the region REh1s does not vary greatly. Therefore, if the threshold is set so that the upper side of the presentation image is included in the region REh1s when the total sum of the target pixels in the region REh1s at this time is compared with the threshold, the region including the side of the presentation image Can be detected correctly. The threshold value may be fixed in advance, or may be set from the sum of target pixels in each region using a statistical method as described above.

  Next, in the region REh1s including the side of the detected presentation image, for example, the region REh1s including the upper side, the presented image detection unit 31 sequentially calculates the sum of the target pixels for each line in the horizontal distribution for each line from the upper end to the lower end of the captured image. Use to compare with threshold. The presentation image detection unit 31 sets a line whose sum exceeds a threshold as the upper side La of the presentation image. Similarly, in the region REh4s including the lower side, the presented image detection unit 31 sequentially uses the sum of the target pixels for each line in the horizontal distribution from the lower end to the upper end of the captured image for each line and compares it with the threshold value. A line exceeding the threshold is set as the lower side Lb of the presentation image. FIG. 8A shows a captured image after binarization processing, and FIG. 8B shows a horizontal distribution. Here, when the region REh1s is determined as the region including the upper side, the sum of the target pixels for each line in the region REh1s is sequentially used for each line from the upper end to the lower end of the captured image and compared with the threshold value. A line exceeding the upper limit La is set as the upper side La of the presentation image. Similarly, when the region REh4s is determined as the region including the lower side, the sum of the target pixels for each line in the region REh4s is sequentially used for each line from the lower end to the upper end of the captured image and compared with the threshold value. A line that exceeds is set as the lower side Lb of the presentation image.

  In this way, even if the total of one line becomes large due to noise or the like by detecting the area including the upper side and the lower side and detecting the upper side and the lower side of the presentation image from the detected area, this line Can be prevented from being erroneously determined as the upper side of the presented image.

  In step ST107, the presentation image detection unit 31 performs detection processing of the left side and the right side of the presentation image, and proceeds to step ST108.

  9 and 10 show the detection processing of the left side and the right side of the presented image. 9A shows a captured image after binarization processing, and FIG. 9B shows the vertical distribution acquired in step ST105. Here, the presentation image detection unit 31 divides the vertical distribution into a plurality of regions, for example, regions REv1 to REv6 and REv1s to REv5s, and obtains the sum of the target pixels for each region. Next, the presented image detection unit 31 sequentially selects areas from the left end to the right end of the captured image, compares the sum of the target pixels in the selected area with a threshold value, and detects an area where the sum exceeds the threshold value. By performing such processing, the region REv2 including the left side of the presented image can be detected. Similarly, the presented image detection unit 31 sequentially selects regions from the right end to the left end of the captured image, compares the sum of the target pixels in the selected region with a threshold value, and detects a region where the sum exceeds the threshold value. By performing such processing, the region REv5 including the right side of the presented image can be detected. The threshold value at this time may be fixed in advance, or may be set from the sum of target pixels in each region using a statistical method as described above.

  Next, the presented image detection unit 31 sequentially uses the sum of the target pixels for each pixel position in the vertical distribution in the detected region, for example, the region REv2 including the left side, sequentially from the left end to the right end of the captured image for each pixel position. In comparison, the pixel position where the sum exceeds the threshold value is defined as the left side Lc of the presentation image. Similarly, in the region REv5 including the right side, the presented image detection unit 31 sequentially uses the sum of the target pixels for each pixel position in the vertical distribution for each pixel position in the direction from the right end to the left end of the captured image and compares it with the threshold value. The pixel position where the sum exceeds the threshold is defined as the right side Ld of the presented image.

  10A shows a captured image after binarization processing, and FIG. 10B shows a vertical distribution. Here, when the region REv2 is determined as a region including the left side, the sum of the target pixels for each pixel position in the region REv2 is sequentially used from the left end to the right end of the captured image and compared with the threshold, and the sum exceeds the threshold. Let the pixel position be the left side Lc of the presentation image. Similarly, when the region REv5 is determined as the region including the right side, the sum of the target pixels for each pixel position in the region REv5 is sequentially used for each line from the right end to the left end of the captured image and compared with the threshold value. A line exceeding the threshold is set as the right side Ld of the presentation image.

  In step ST108, the presentation image detection unit 31 determines whether or not the presentation image is present. The presented image detection unit 31 determines the aspect ratio from the upper side and the lower side and the left side and the right side detected in steps ST106 and ST107. The presented image detection unit 31 discriminates when the aspect ratio approximates the aspect ratio of the presented image, for example, the aspect ratio “4: 3”, “16: 9”, etc. used in television broadcasting. When the aspect ratio is “4: 3 ± α” and “16: 9 ± β”, the region surrounded by the sides detected in step ST106 and step ST107 is determined as the presentation image, and the presentation image detection process is terminated. Proceed to step ST2 in FIG. “Α” and “β” are constants indicating an allowable range for determining that the image is a presentation image, and are set in advance. In this way, by determining whether or not the aspect ratio approximates the desired aspect ratio, it is possible to easily determine the area of the presentation image from the captured image when a presentation image with a predetermined aspect ratio is captured. It becomes possible to do.

  In addition, when the presented image detection unit 31 cannot detect the upper and lower sides and the left and right sides of the presented image, the aspect ratio determined based on the detected upper and lower sides and the left and right sides approximates the desired aspect ratio. If not, the process proceeds to step ST109 assuming that the presented image is not detected.

  FIG. 11 is a diagram for explaining a determination operation as to whether or not the image is a presentation image. For example, as shown in FIGS. 11A and 11B, the upper side La and the lower side Lb, the left side Lc and the right side Ld are detected, and an image surrounded by the detected upper side, lower side, left side and right side is presented. When the aspect ratio of the image is not approximated, it is determined that the image is not a presentation image, and the process proceeds to step ST109.

  In step ST109, the presentation image detection unit 31 determines whether the presentation image is detected for the first time. When the presentation image is detected using the luminance binarized signal, the presentation image detection unit 31 proceeds to step ST110 because the presentation image is detected for the first time.

  In step ST110, the presentation image detection unit 31 selects the color difference binarized signal, returns to step ST104, and repeats the processing from step ST104.

  The presentation image detection unit 31 detects the presentation image based on the color difference binarized signal by repeating the processing from step ST104. The presented image detection unit 31 cannot detect the upper and lower sides and the left and right sides of the presented image, or the aspect ratio determined based on the detected upper and lower sides and the left and right sides approximates the desired aspect ratio. If not, the process proceeds from step ST108 to step ST109.

  Thus, if the presentation image is detected using not only the luminance binarization signal but also the color difference binary signal, the presentation image can be detected from the difference in color. For example, even if it is difficult to distinguish the presentation image from the background image based on the luminance binarization signal because the luminance difference between the presentation image and the background image is small, the presentation image is based on a color different from the background image. When it is an image, the presented image can be detected from the difference in color. This presented image has a feature that it has a larger luminance value and a darker color than natural scenery. Here, the color density can be expressed using the magnitude of the color difference component in the color space of the YCC space or Lab space or the magnitude of the saturation in the HSV space. Therefore, if the presentation image is detected using the intensity of the color difference component and the magnitude of the saturation, the presentation image and the background image can be detected even if it is difficult to distinguish the presentation image and the background image based on the luminance difference. It becomes possible to classify, and a presentation image can be detected with high accuracy.

  In step ST109, the presentation image detection unit 31 determines whether the presentation image is detected for the first time. The presentation image detection unit 31 detects the presentation image using the luminance binarization signal and the color difference binarization signal. Since the presentation image is not detected for the first time, the process ends and step ST2 in FIG. 4 is performed. Proceed to

  In addition, the detection of a presentation image is not restricted to the process shown in FIG. For example, by performing edge detection of the captured image, a contour indicating the boundary between the presentation image and the background image is acquired, and straight lines indicating four vertices and four sides of the presentation image are obtained from the contour information, and the presentation image is obtained. It is good also as what detects.

  In step ST2 of FIG. 4, the control unit 51 determines whether or not the condition for switching to the presentation image capturing mode is satisfied. When the control unit 51 determines that the condition for switching to the presentation image imaging mode is satisfied, the control unit 51 sets the imaging mode to the presentation image imaging mode, and proceeds to step ST3. When it is determined that the condition is not satisfied, the imaging mode is set to another imaging mode (for example, the normal imaging mode), and the process proceeds to step ST5.

  The control unit 51 determines whether or not the condition for switching to the presentation image capturing mode is satisfied according to the generation state of the frame in which the presentation image is detected. For example, the control unit 51 counts up every time a frame in which a presentation image is detected is generated, and counts down every time a frame in which a presentation image is not detected occurs. Note that the range of the count value is set to “0” to “about several tens”. Here, when the count value is equal to or greater than a threshold value set in advance for determining the imaging mode (hereinafter referred to as “mode determination threshold value”), the presentation image imaging mode is set and the count value is less than the mode determination threshold value If so, set to normal imaging mode.

  Moreover, the control part 51 is good also as what sets the imaging mode based on the continuous number of the frames from which the presentation image was detected, or the continuous number of the frames from which the presentation image was not detected. For example, when the number of consecutive frames in which the presentation image is detected reaches a predetermined number, the imaging mode is switched from the normal imaging mode to the presentation image imaging mode. When the number of consecutive frames in which no presentation image is detected reaches a predetermined number, the imaging mode is switched from the presentation image imaging mode to the normal imaging mode. In this way, it is possible to stably switch the imaging mode according to the detection state of the presented image.

  In step ST3, the control unit 51 performs a presentation image capturing mode notification process and proceeds to step ST4. The control unit 51 notifies the user that the imaging device 10A is set to the presentation image imaging mode. For example, when the presentation image capturing mode is set, the control unit 51 generates the display signal HE and supplies the display signal HE to the image processing unit 35 to generate the display image signal HG from the image signal DVa and the display signal HE. As a result, the control unit 51 displays information indicating that the captured image and the presentation image capturing mode are set on the screen of the display unit 38. FIG. 12 shows a case where an icon display MH indicating that the presentation image imaging mode is set is provided on the captured image displayed on the display unit 38.

  In step ST4, the control unit 51 determines the position of the presentation image based on the detection signal JA, performs weighting coefficient setting processing according to the presentation image position, and proceeds to step ST7.

  FIG. 13 is a diagram for explaining the operation of the detection unit 32. The detector 32 divides the captured image into a plurality of blocks, for example (m × n), as shown in FIG. In addition, when the captured image has the composition shown in FIG. 13B and the presentation image is detected, the weight of the block that does not include the presentation image is shown so as not to be affected by the presentation image. Increase as shown in 13 (C). For example, the weight coefficient of the block including the presentation image is set to “0”, and the weight coefficient of the block of the background image is increased.

  In step ST5, the control unit 51 performs a normal imaging mode notification process and proceeds to step ST6. The control unit 51 notifies the user that the imaging apparatus 10A is set to the normal imaging mode. For example, when the presentation image imaging mode is set, the control unit 51 can identify that the normal imaging mode is set by stopping the supply of the display signal HE and erasing the icon display MH. Like that.

  In step ST6, the control unit 51 controls the detection unit 32 to perform a weighting factor setting process in which the weight of the central part is increased, and the process proceeds to step ST7. That is, when in the normal imaging mode, the control unit 51 sets the weighting coefficient so that the weight of the central block in the captured image becomes higher as shown in FIG.

  When the weighting factor is set according to the imaging mode, the detection unit 32 provides a detection area in the captured image and generates a detection signal JB from the image signal in the detection area. That is, the detection unit 32 divides the captured image into blocks, weights the sum of the signals indicating the brightness of each pixel in the block, weights the weight coefficient W, adds the sum after weighting, and detects the detected value Vjb. , And a detection signal JB indicating the detection value Vjb is generated.

  Here, the sum of the luminance signals of each pixel included in the block of coordinates (a, b) is BT (a, b), and the weighting factor for the block of coordinates (a, b) is W (a, b). At this time, the detection unit 32 generates a detection value Vjb based on the equation (1).

It should be noted that the normalized detection value Vjb can be obtained by normalizing the sum of the weight coefficients to 1.

  In step ST7, the control unit 51 performs exposure control based on the detection signal JB generated by the detection unit 32, and proceeds to step ST8. Here, in the detection part 32, the detection signal JB is produced | generated using the weighting coefficient W set by the weighting coefficient setting process of step ST4 or step ST6. The control unit 51 generates at least one of the control signals CTb, CTc, and CTd based on the detection signal JB generated by the detection unit 32. The control unit 51 supplies the generated control signal CTb to the aperture driving unit 42, the control signal CTc to the timing signal generation unit 22, and the control signal CTd to the amplification unit 213. The control unit 51 performs aperture setting of the aperture mechanism 12, adjustment of exposure time by the timing signal generation unit 22, and gain adjustment of the image signal Sa by the amplification unit 213 so as to achieve proper exposure.

  In step ST8, the control unit 51 determines whether or not the imaging operation is finished. The control unit 51 ends the brightness control when, for example, a power-off operation of the imaging apparatus 10A is performed or an operation for switching from the imaging mode to the playback mode for reproducing the recorded image is performed. When the power-off operation or the switching operation to the reproduction mode is not performed, the process returns to step ST1.

In this way, the detection area is set at a position different from the detected presentation image by detecting the position of the presentation image, that is, the weight is dynamically changed so that the presentation image is not included in the block whose weight is increased. Then, brightness control is performed without being affected by the presented image. Accordingly, it is possible to prevent the influence of the presented image and obtain a captured image in which the presented image has an appropriate brightness. In addition, even when the design of the presentation image changes dynamically due to a moving image or a slide show, brightness control that follows the change of the presentation image is not performed, preventing fluctuations in brightness, etc. An easy-to-view captured image can be obtained. In addition, when the presented image is dark, it is possible to prevent the strobe light from being emitted so that the presented image can be captured with an appropriate brightness. Therefore, it is possible to obtain a captured image in which the presented image has an appropriate brightness. Can do.
<2. Second Embodiment>
[Switching the presentation image capture mode by user operation]

  By the way, in the above-described embodiment, the process of detecting the presentation image from the captured image is performed, and when the presentation image is detected, the imaging mode is automatically switched to the presentation image imaging mode. For this reason, if a presentation image cannot be detected, brightness control cannot be performed automatically without being affected by the presentation image. If the detection accuracy of the presented image is low, the detection unit cannot correctly provide a detection region at a position different from the detected presentation image.

  Therefore, the imaging mode may be switched manually so that the brightness control can be performed without being influenced by the presented image even when the presented image is not detected. In addition, when a presented image is captured, the presented image is often located approximately at the center of the captured image, and therefore a detection region is provided on at least one side excluding the edge of the captured image, that is, the center of the captured image. It is good.

  FIG. 14 shows a configuration of an imaging apparatus 10B as the second embodiment. The same components as those of the imaging device 10A shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. The imaging device 10B illustrated in FIG. 14 manually switches the imaging mode, and does not include the presentation image detection unit 31 illustrated in FIG.

  The user interface unit 52 connected to the control unit 51 generates an operation signal PS corresponding to the user operation and supplies the operation signal PS to the control unit 51. The control unit 51 generates a control signal corresponding to the operation signal PS and supplies it to each unit, thereby controlling the operation of the imaging device 10B to be an operation corresponding to the user operation.

  For example, when the user selects the presentation image capturing mode, the control unit 51 inputs an operation signal PS indicating the presentation image capturing mode. When the operation signal PS indicating the presentation image capturing mode is input, the control unit 51 outputs a control signal CTe for changing the detection region to the detection unit 32. For example, the control unit 51 increases the weight of a block located on at least one side of the captured image, for example, at the end of the captured image as illustrated in FIG. 17A, and sets the weight of other blocks to “0”. The control signal CTe for changing the detection region to be output is output to the detection unit 32.

  Based on the control signal CTe supplied from the control unit 51, the detection unit 32 sets a weight for each block of the captured image and obtains the detection signal JB. In this example, the block whose weight is set to “0” is not used for calculation of the detection value, and the block whose weight is increased has a high contribution ratio to the detection value. In this way, the detection area is changed by switching the weighting.

  In addition to the method of changing the detection region of the detection unit 32 by switching the weighting described above, the control unit 51 obtains the luminance value of only the block used as the detection region among the blocks of the captured image. The signal CTe may be generated. In this case, the detection unit 32 supplies the addition result of the luminance value signal for each block acquired based on the control signal CTe to the control unit 51 as the detection signal JB.

  The control unit 51 generates a control signal CTb based on the detection signal JB obtained by the detection unit 32 and supplies the control signal CTb to the aperture driving unit 42, so that a desired subject in the captured image has an optimal brightness. The amount of light incident on 21 is adjusted. In addition, the control unit 51 generates a control signal CTc based on the detection signal JB and supplies the control signal CTc to the timing signal generation unit 22, thereby adjusting the exposure time so that a desired subject in the captured image has optimum brightness. In addition, the control unit 51 generates the control signal CTd based on the detection signal JB and supplies the control signal CTd to the amplification unit 213, thereby adjusting the gain of the image signal Sa so that a desired subject in the captured image has an optimal brightness. .

  FIG. 15 shows an imaging mode selection menu display when the imaging mode is switched manually. For example, the control unit 51 controls the operation of the display unit 38 to display an imaging mode selection menu as shown in FIG. Further, for example, a touch panel is used as the user interface unit 52, and this touch panel is provided on the display screen of the display unit 38, and the display unit 38 and the user interface unit 52 constitute a GUI (Graphical User Interface). Here, when the user touches the icon display of the desired imaging mode, the user switches to the touched imaging mode. For example, as shown in FIG. 15B, when the icon display “screen & monitor” for switching to the presentation image imaging mode is touched by the user, the imaging mode is switched to the presentation image imaging mode. In addition, as a cursor display on the display unit 38, a desired imaging mode may be selected by moving the cursor according to a key operation of the user interface unit 52.

  FIG. 16 shows a flowchart for manually switching the imaging mode. The control unit 51 of the imaging device 10B determines whether or not the presentation image imaging mode is selected in step ST21. The control unit 51 proceeds to step ST22 when the user has selected the presentation image capturing mode, and proceeds to step ST24 when the user has not selected the presentation image capturing mode. It should be noted that when the user has not selected the presented image capturing mode, another capturing mode, for example, the normal capturing mode is set.

  In step ST22, the control unit 51 performs a presentation image capturing mode notification process in the same manner as in step ST3, notifies the user that the imaging device 10B is set to the presentation image capturing mode, and proceeds to step ST23.

  In step ST23, the control unit 51 controls the detection unit 32 to perform a weighting factor process with a higher end weight, and proceeds to step ST26. When a presentation image is captured, the presentation image is often located approximately at the center of the captured image as described above. Therefore, the control unit 51 controls the detection unit 32 to provide a detection region on at least one side of the captured image and generate the detection signal JB. In addition to the method of changing the detection region of the detection unit 32 by switching the weighting described above, the control unit 51 acquires the luminance value of only the block used as the detection region among the blocks of the captured image. Alternatively, the detector 32 may be controlled. In this case, the detection unit 32 supplies the addition result of the luminance value signal for each block to the control unit 51 as the detection signal JB.

  In step ST24, the control unit 51 performs normal imaging mode notification processing in the same manner as in step ST5, notifies the user that the imaging device 10B is set to the normal imaging mode, and proceeds to step ST25.

  In step ST25, the control unit 51 controls the detection unit 32 to perform a weighting factor setting process in which the weight of the central portion is increased as in step ST6, and the process proceeds to step ST26.

  In step ST26, similarly to step ST7, the control unit 51 performs exposure control based on the detection signal JB generated by the detection unit 32, and proceeds to step ST27.

  In step ST27, the control unit 51 determines whether or not the imaging operation is finished. The control unit 51 ends the brightness control when, for example, a power-off operation of the imaging device 10B is performed or an operation of switching from the imaging mode to the reproduction mode for reproducing the recorded image is performed. When the power-off operation or the switching operation to the reproduction mode is not performed, the process returns to step ST21.

  In this way, even when the presentation image cannot be detected, it is possible to switch to the presentation image imaging mode and obtain a captured image in which the presentation image has an appropriate brightness. Further, even when the detection accuracy of the presentation image is low and the position of the presentation image cannot be detected with high accuracy, the detection of the presentation image detects whether the presentation image is included in the captured image. When it is detected that the presented image is included in the captured image, the captured image is automatically switched to the presented image capturing mode, and a detection area is provided on at least one side of the captured image. A captured image having an appropriate brightness can be obtained.

  As described above, when the presentation image capturing mode is set, the weight of the block positioned at least on one side of the captured image, for example, at the end of the captured image as shown in FIG. The weighting is “0” (blocks indicated by hatching). In this case, when the presentation image is captured as shown in FIGS. 17B and 17C, the weights of the blocks located at the ends of the captured image are shown in FIGS. 17D and 17E. Is increased, and the block of the presented image is removed from the detection region. Therefore, even when the presentation image cannot be detected, for example, when the presentation image is an image based on blue or black, a dark portion such as black in the presentation image may be lifted or a white character or a picture in the presentation image may be bright It is possible to obtain a captured image in which the portion is too bright and is not crushed. Further, even when the presented image is dark, it is possible to obtain a captured image in which the strobe light emission is stopped and the presented image has an appropriate brightness.

  In addition, when capturing the presentation image projected on the screen with the room illumination turned off, when the exposure control is fixed so that the presentation image has an optimum brightness, when the room illumination is turned on, Not only does the entire room become bright, but the presented image is too bright and difficult to see as shown in FIG. However, when the presentation image capturing mode is set and weighting is performed as illustrated in FIG. 17A, the detection value is calculated from the end of the captured image as illustrated in FIG. Brightness control is performed according to the brightness of the room. Therefore, as shown in FIG. 18C, it is possible to automatically obtain a captured image whose brightness is suppressed in accordance with the illumination state of the room.

  In addition, the setting process of the weighting coefficient in the presentation image capturing mode is not limited to the case where the weights of the upper, lower, left, and right edges of the captured image are increased as shown in FIG. For example, in television programs and the like, the aspect ratio of display images is often set to “16: 9”. On the other hand, the presentation image projected on the screen often has an aspect ratio of “4: 3”. For this reason, when the presentation image projected on the screen is captured from the front, the presentation image is not reflected on the left and right ends of the captured image as shown in FIG. Accordingly, as shown in FIG. 19B, by increasing the weights of the left and right end blocks and decreasing the weights of the other blocks to, for example, “0”, the influence of the projected presentation image is further increased. The brightness can be easily controlled with less.

It is a figure which shows the structure of the imaging device which concerns on 1st Embodiment. It is a figure which shows the structure of a presentation image detection part. It is a figure which shows the structure of a detection part. It is a flowchart which shows the exposure control operation | movement in an imaging device. It is a flowchart which shows a presentation image detection operation | movement. It is a figure which shows the acquisition process of a horizontal distribution and a vertical distribution. It is a figure which shows the detection process of the upper side and lower side of a presentation image. It is a figure which shows the detection process of the upper side and lower side of a presentation image. It is a figure which shows the detection process of the left side and right side of a presentation image. It is a figure which shows the detection process of the left side and right side of a presentation image. It is a figure for demonstrating the discrimination | determination operation | movement of whether it is a presentation image. It is a figure which shows the case where the icon display which shows having been set to the presentation image imaging mode is provided. It is a figure for demonstrating operation | movement of a detection part. It is a figure which shows the structure of the imaging device which concerns on 2nd Embodiment. It is a figure which shows an imaging mode selection menu display. It is a flowchart in the case of switching an imaging mode manually. It is a figure which shows operation | movement when it is set as presentation image imaging mode. It is a figure which shows operation | movement when illumination is turned on. It is a figure which shows other operation | movement of weighting. It is the figure which showed the case where the mode of a presentation is imaged with an imaging device, for example. It is the figure which showed the case where the presentation image projected, for example on the screen with an imaging device is imaged. It is the figure which showed the case where the presentation image currently displayed on the screen of a television apparatus is imaged with an imaging device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10A, 10B ... Imaging device, 11 ... Lens part, 12 ... Diaphragm mechanism, 21 ... Imaging part, 22 ... Timing signal generation part, 23 ... A / D conversion part, 31 ... presented image detection unit, 32 ... detection unit, 35 ... image processing unit, 37 ... recording / reproducing unit, 38 ... display unit, 41 ... lens drive unit, 42 ... Diaphragm drive unit, 45... Strobe, 51... Control unit, 52... User interface unit, 211... Image sensor, 212. White balance (WB) adjustment unit, 351a, white balance detection unit, 351b, white balance correction coefficient setting unit, 351c, correction processing unit, 352, gamma correction unit, 311 ... conversion processing Part, 312,313 ... binarization processing 315 ... Horizontal distribution acquisition unit, 316 ... Vertical distribution acquisition unit, 317 ... Detection processing unit, 321 ... Blocking processing unit, 322 ... Brightness calculation unit for each block, 323 ... Coefficient setting unit, 324 ... multiplier, 325 ... detection value calculation unit

Claims (10)

An imaging unit that captures an image of a subject and obtains an image signal;
A detection unit that sets a detection region for a captured image based on an image signal obtained by the imaging unit, and calculates a detection value from the image signal in the detection region;
An exposure adjustment section for adjusting the exposure;
A control unit that controls the exposure adjustment unit so that the detection value becomes a predetermined value;
A presentation image detection unit that detects a presentation image presented by the image presentation device from the captured image based on a difference in luminance in the captured image;
An imaging device that sets the detection region at a position different from the detected presentation image when the presentation image detection unit detects the presentation image.   When the presentation image detection unit only detects whether or not the presentation image is included in the captured image, the detection unit detects that the presentation image is included in the captured image The imaging apparatus according to claim 1, wherein the detection region is provided on at least one side excluding a center portion of the captured image. The imaging unit obtains an image signal of the captured image that has a horizontally long aspect ratio than the presented image;
The imaging device according to claim 2, wherein the detection unit provides the detection region in a region that is not the presentation image generated in the captured image due to the difference in the aspect ratio. A user interface unit that generates an operation signal corresponding to a user operation;
The imaging according to claim 1 or 2, wherein when the operation signal indicates an imaging mode selection operation for capturing the presented image, the detection unit provides the detection region on at least one side of the captured image. apparatus.   The exposure variable unit varies at least one of a light amount incident on the imaging unit, a gain of an image signal output from the imaging unit, and an exposure time when the image signal is obtained by the imaging unit. Imaging device. The presented image detection unit
A binarization processing unit that compares a luminance and a threshold for each pixel of the captured image and generates a binarized signal indicating the comparison result;
A distribution acquisition unit that acquires horizontal and vertical distributions of pixels exceeding the threshold from the binarized signal;
The imaging according to claim 1, further comprising: a detection unit that detects horizontal and vertical sides of the presentation image from the horizontal distribution and vertical distribution, and sets a region surrounded by the detected sides as the position of the presentation image. apparatus. An imaging step of obtaining an image signal by imaging an object by an imaging unit;
A detection step of setting a detection region for a captured image based on the obtained image signal and calculating a detection value from the image signal of the detection region;
A presentation image detection step of detecting the presentation image presented by the image presentation device from the captured image based on a difference in luminance in the captured image;
An exposure adjustment step for performing exposure adjustment with the detection value as a predetermined value;
An exposure control method for setting the detection area at a position different from the detected presentation image in the detection step when the presentation image is detected in the presentation image detection step. An imaging unit that captures an image of a subject and obtains an image signal;
A detection unit that sets a detection region for a captured image based on an image signal obtained by the imaging unit, and calculates a detection value from the image signal in the detection region;
An exposure adjustment section for adjusting the exposure;
A control unit that controls the exposure adjustment unit so that the detection value becomes a predetermined value;
An imaging apparatus in which the detection unit provides the detection area on at least one side excluding the central part of the captured image in a presentation image imaging mode in which a presentation image presented by an image presentation apparatus is captured. A user interface unit that generates an operation signal corresponding to a user operation;
The imaging apparatus according to claim 8, wherein when the operation signal indicates an operation for selecting the presentation image imaging mode, the detection unit provides the detection area on at least one side of the captured image. An imaging step of obtaining an image signal by imaging an object by an imaging unit;
A detection step of setting a detection region for a captured image based on the obtained image signal and calculating a detection value from the image signal of the detection region;
An exposure adjustment step of performing exposure adjustment with the detection value as a predetermined value;
A mode selection step of selecting a presentation image imaging mode for imaging a presentation image presented by the image presentation device;
An exposure control method for providing the detection region on at least one side excluding the center of the captured image in the detection step when the presentation image capturing mode is selected in the mode selection step.