JP2010213220A - Imaging apparatus, and imaging control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To pick up an image free of exposure unevenness even in a scene affected by flash light emission from other person, in a rolling shutter system imaging apparatus. <P>SOLUTION: Exposure starts with a delay in exposure start timing for each line for a CMOS sensor without using a mechanical shutter, and imaging with the rolling shutter system is performed to read information on each line sequentially, starting from a line where a predetermined exposure time has passed, so that an image of one frame of an object to be recorded is acquired (at step S10). Existence or non-existence of exposure unevenness due to other person's flash light emission contained in the acquired image of the object to be recorded is detected (at step S12). When exposure unevenness is detected, a warning indicating the exposure unevenness is issued (at step S16), and recording processing is performed or is canceled dependent on recording/cancel instruction input from a photographer (at steps S18 and S20). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus and an imaging control method, and more particularly to a technique applied to a rolling shutter imaging apparatus.

  In a camera equipped with a focal plane shutter, there has been proposed an imaging apparatus that avoids in-plane exposure unevenness by matching flash emission and exposure timing (Patent Document 1).

  In addition, in an imaging apparatus using a CMOS sensor, exposure is started by shifting the exposure start timing for each line as a method of electronically realizing a shutter similar to the focal plane shutter without using the focal plane shutter. In addition, a rolling shutter system is known in which information on a line is sequentially read from a line where a predetermined exposure time has elapsed.

  This rolling shutter system is characterized in that there is a time difference between the exposure timing and the readout timing for each line. Therefore, when strong light with a short light emission period such as a flash is incident during the exposure period of some lines, the rolling shutter system is one of the features. There is a problem that the area of the part line becomes brighter than other line areas (in-plane luminance unevenness occurs).

  In order to reduce luminance unevenness due to the rolling shutter system, Patent Document 2 discloses an imaging apparatus that always emits flash from the exposure timing of the first line to the end of exposure of the last line.

JP 2006-64974 A JP 2007-324649 A

  However, the inventions described in Patent Documents 1 and 2 are techniques for reducing luminance unevenness when a flash is emitted from a flash device provided in the imaging device itself. If it is a flash device provided in the imaging device itself, the light emission timing can be controlled, but the flash light emission timing of the camera owned by another person cannot be controlled.

  For example, in a scene where many cameras, such as weddings and press conferences, simultaneously emit flash, when shooting with a rolling shutter type imaging device, the screen is exposed to the flash light emitted by the camera owned by another person. Although unevenness occurs, this problem cannot be solved by the inventions described in Patent Documents 1 and 2.

  The present invention has been made in view of such circumstances, and in a rolling shutter type imaging apparatus, an imaging apparatus capable of capturing an image without exposure unevenness even in a scene where there is flash emission by another person, and imaging control It aims to provide a method.

  In order to achieve the above object, according to the first aspect of the present invention, an image sensor having a plurality of light receiving areas starts exposure by shifting the exposure start timing for each line, and a predetermined exposure time elapses. In a rolling shutter type imaging apparatus that sequentially reads out information on a line from a line that has been recorded, the image is a single frame that includes information of a plurality of lines that are sequentially read from the imaging element, and is one frame to be recorded in synchronization with a shutter release operation. An image acquisition means for acquiring an image of a plurality of frames including an image of the image or an image of an adjacent frame, and exposure resulting from flash emission of another person included in the acquired image of one frame to be recorded Exposure unevenness detecting means for detecting the presence or absence of unevenness, and when exposure unevenness is detected by the exposure unevenness detecting means, exposure Is characterized with uneven exposure warning means for issuing a warning indicating La, further comprising a.

  That is, the presence / absence of exposure unevenness (exposure unevenness caused by flash emission of others) in one frame image to be recorded is detected, and if exposure unevenness is detected, a warning indicating the exposure unevenness is issued. I have to. Re-imaging is triggered by this warning, and the photographer can capture an image without uneven exposure by performing re-imaging.

  According to a second aspect of the present invention, in the imaging apparatus according to the first aspect, a warning is issued by the internal memory in which the image acquired by the image acquisition unit is temporarily recorded, the image display unit, and the exposure unevenness warning unit. When issued, a display control means for displaying the image recorded in the internal memory on the image display means, a recording instruction means for inputting recording of the image, and the image unevenness warning is issued by the recording instruction means The image processing apparatus further includes recording means for recording the image recorded in the internal memory on a non-volatile recording medium when a recording instruction for the image is input.

  That is, when exposure unevenness is detected in the image to be recorded, the image to be recorded is temporarily stored in the internal memory and displayed on the image display means. You can get confirmation. When the exposure unevenness is erroneously detected or when the exposure unevenness is acceptable, when a recording instruction is input from the photographer, the image recorded in the internal memory is recorded on a non-volatile recording medium. .

  According to a third aspect of the present invention, in the imaging apparatus according to the second aspect, the exposure unevenness detection unit detects a line position indicating at least a boundary of exposure unevenness parallel to the line direction, and the exposure unevenness warning unit includes the exposure unevenness warning unit. A marker indicating the detected line position is displayed on the image displayed on the image display means. Thereby, the photographer can easily check the presence or absence of exposure unevenness.

  According to a fourth aspect of the present invention, an image sensor having a plurality of light-receiving areas starts exposure by shifting the exposure start timing for each line, and information on the lines sequentially from a line where a predetermined exposure time has passed. In a rolling shutter type imaging apparatus that reads out image data, a 1-frame image composed of information of a plurality of lines read out from the imaging device, and a 1-frame image to be recorded synchronized with a shutter release operation, are adjacent to the image. Image acquisition means for acquiring images of a plurality of frames including a frame image, and exposure unevenness detection for detecting presence or absence of exposure unevenness caused by flash emission of another person included in the acquired image of one frame to be recorded And when the exposure unevenness is detected by the exposure unevenness detection means, the exposure unevenness of the image to be recorded is detected. High information of the luminance area is characterized by comprising an exposure unevenness correcting means for correcting, based on the information corresponding to the high luminance region in the image of the adjacent frames.

  That is, in addition to an image of a recording target frame synchronized with the shutter release operation, an image of a frame adjacent to the image is also acquired, and when exposure unevenness is detected in the recording target image, The image of the frame adjacent to the image to be recorded is used, and the information of the high brightness area corresponding to the exposure unevenness is corrected based on the information corresponding to the high brightness area in the image of the adjacent frame. Thereby, exposure unevenness can be automatically corrected, and an image without exposure unevenness can be recorded.

  5. The imaging apparatus according to claim 4, wherein the exposure unevenness correction unit is configured to display information on a high brightness area corresponding to the exposure unevenness of the image to be recorded in the image of the adjacent frame. It replaces with the information corresponding to the said high-intensity area | region, It is characterized by the above-mentioned.

  According to a sixth aspect of the present invention, in the imaging device according to the fourth aspect, the exposure unevenness correcting unit converts the brightness value of a line corresponding to a high brightness area corresponding to the exposure unevenness of the image to be recorded into the high brightness area. The correction is performed so that the average luminance value of the line corresponding to the luminance region matches the average luminance value of the same line in the image of the adjacent frame.

  That is, the invention according to claim 5 replaces the information of the high luminance area corresponding to the exposure unevenness of the image to be recorded with the information corresponding to the high luminance area in the image of the adjacent frame, thereby obtaining the high luminance area. However, in the invention according to claim 6, the information of the high luminance region is corrected for each line so as to match the average luminance of the same line in the image of the adjacent frame. The information on the brightness area is corrected.

  In the imaging apparatus according to any one of claims 4 to 6, as described in claim 7, when exposure unevenness is detected by the exposure unevenness detection means, an exposure unevenness warning unit that issues a warning indicating exposure unevenness, and an image A display means, a display control means for displaying the image to be recorded on the image display means when the warning is issued by the exposure unevenness warning means, a correction instruction means for inputting an instruction for correcting exposure unevenness, and the exposure The unevenness correcting means corrects exposure unevenness of the image to be recorded when a correction instruction for an image for which the image unevenness warning has been issued is input by the correction instruction means.

  That is, when exposure unevenness is detected in an image to be recorded, the exposure unevenness is not corrected immediately, a warning indicating exposure unevenness is issued, and the image to be recorded is displayed on the image display means. When an exposure unevenness correction instruction is input from the photographer, exposure unevenness correction is performed. Thereby, it is possible to prevent erroneous correction when exposure unevenness is erroneously detected.

  The imaging apparatus according to any one of claims 1 to 7, wherein the exposure unevenness detection unit is configured to obtain an average luminance for each line or for each of a plurality of lines from the acquired image of one frame to be recorded. A luminance value calculating means for calculating a value, and a luminance change detecting means for detecting a luminance change exceeding a predetermined threshold between lines in the front-rear direction based on the calculated average luminance value, and the luminance change detecting means It is characterized in that the presence or absence of the exposure unevenness is detected based on the presence or absence of the detected luminance change.

  The in-plane exposure unevenness caused by the flash emission of others is that the brightness of the first half or the second half of a certain line (the line receiving the flash light and the line not receiving the light) is higher than the other parts. The brightness is high. Accordingly, the average luminance value for each line or a plurality of lines is calculated from the image to be recorded, and the presence or absence of exposure unevenness is detected by detecting a portion where the average luminance value changes significantly in the front-rear direction of the line. I have to.

  The imaging apparatus according to any one of claims 1 to 8, wherein the exposure unevenness detection unit is configured to detect each line or each line from a plurality of frames of images acquired by the image acquisition unit. A luminance value calculating means for calculating an average luminance value; and an average luminance value of lines of the image to be recorded based on an average luminance value calculated for the same line of the images of the plurality of frames is an average of lines of adjacent images High luminance line detecting means for detecting a line larger than the luminance value, and detecting the presence or absence of the exposure unevenness based on the presence or absence of the high luminance line detected by the high luminance line detecting means. Yes.

  When another person's flash light is incident on a certain line of the image to be recorded, it is considered that the rush light is not incident on the same line of the image of the frame adjacent to the image to be recorded. This is because the emission time of flash light (flash light from a general xenon tube) is extremely short. Therefore, when the average luminance value of an arbitrary line of the image to be recorded is larger than the average luminance value of the same line of the adjacent image, it is considered that flash light is incident on that line. In this way, the presence or absence of exposure unevenness is detected from the presence or absence of a line (high luminance line) having higher brightness than the image of the adjacent frame.

  The imaging apparatus according to any one of claims 4 to 7, wherein the image acquisition unit includes one frame image to be recorded and images of frames immediately before and after the image. The three-frame image is acquired, and the exposure unevenness correcting unit is configured to select one of the immediately preceding and immediately following frame images as the adjacent frame image used for correcting the exposure unevenness of the image to be recorded. It has the selection means to select.

  The imaging device according to claim 10, wherein the selection unit is the same in the images of the immediately preceding and following frames corresponding to the high-intensity region corresponding to the exposure unevenness of the image to be recorded. Calculation means for calculating the average luminance value of each region is provided, and an image having a low average luminance value is selected from the calculated average luminance values.

  As a result, it is possible to select an image that is not partly flash exposed as a correction image.

  The imaging device according to claim 10, wherein the selection unit determines whether a high brightness area corresponding to the exposure unevenness of the image to be recorded is a first half or a second half of the image. It has a determination means, and when it is determined that it is the first half, the image of the immediately following frame is selected, and when it is determined that it is the second half, it selects the image of the immediately preceding frame.

  Accordingly, it is possible to select an image side far from the flash emission point, and it is possible to select an image not subjected to flash exposure as a correction image.

  According to the thirteenth aspect of the present invention, the image sensor having a plurality of light-receiving regions starts exposure by shifting the exposure start timing for each line, and information on the lines sequentially from a line where a predetermined exposure time has passed. In the imaging control method in the rolling shutter type imaging apparatus that reads out the image, a one-frame image including information of a plurality of lines sequentially read from the imaging device, and a one-frame image to be recorded in synchronization with the shutter release operation, or Obtaining an image of a plurality of frames including the image and an image of an adjacent frame, detecting presence / absence of exposure unevenness caused by flash emission of another person included in the obtained image of one frame to be recorded, When exposure unevenness is detected, a warning indicating exposure unevenness is issued.

  In the imaging control method according to claim 13, when the exposure unevenness is detected, an image to be recorded on which the exposure unevenness is detected is displayed on an image display unit, and the display result is displayed. When there is an instruction input for instructing recording of an image from the confirmed photographer, the image to be recorded is recorded on a non-volatile recording medium.

  According to the fifteenth aspect of the present invention, an image sensor having a plurality of light-receiving regions starts exposure by shifting the exposure start timing for each line, and information on the lines sequentially from a line where a predetermined exposure time has elapsed. In the imaging control method in the rolling shutter type imaging apparatus for reading out the image, a 1-frame image composed of information of a plurality of lines read from the imaging device, the 1-frame image to be recorded synchronized with the shutter release operation, Obtaining an image of a plurality of frames including an image and an image of an adjacent frame, detecting presence or absence of exposure unevenness caused by flash emission of another person included in the obtained image of one frame to be recorded; When unevenness is detected, the information on the high brightness area corresponding to the exposure unevenness of the image to be recorded is Is characterized in that corrected based on the information corresponding to the high luminance region in the frame image.

  16. The imaging control method according to claim 15, wherein the correction of the information on the high brightness area corresponding to the exposure unevenness is information on the high brightness area corresponding to the exposure unevenness of the image to be recorded. Is replaced with information corresponding to the high-intensity region in the image of the adjacent frame.

  17. The imaging control method according to claim 15, wherein the correction of the information on the high brightness area corresponding to the exposure unevenness corresponds to the high brightness area corresponding to the exposure unevenness of the image to be recorded. In this case, the luminance value of the line to be corrected is corrected so that the average luminance value of the line corresponding to the high luminance area matches the average luminance value of the same line in the image of the adjacent frame.

  In the imaging control method according to any one of claims 13 to 17, as described in claim 18, when the exposure unevenness is detected, information on a high-luminance area corresponding to the exposure unevenness of the image to be recorded is recorded. Before the correction, a warning indicating exposure unevenness is generated and the image to be recorded is displayed on the image display means. After that, when an instruction to correct the exposure unevenness is input, a high brightness area corresponding to the exposure unevenness It is characterized by correcting the information.

  According to the present invention, in a rolling shutter type imaging device, it is possible to detect exposure unevenness due to flash emission of others, and when exposure unevenness is detected, a warning is issued to prompt re-imaging, Alternatively, since the information of the high luminance area corresponding to the exposure unevenness is corrected using the image of the adjacent frame, it is possible to capture an image without the exposure unevenness even in the scene where the flash emission of the other person exists.

FIG. 1 is a block diagram showing an internal configuration of an imaging apparatus according to the present invention. FIG. 2 is a flowchart showing the first embodiment of the imaging control method according to the present invention. FIG. 3 is a timing chart showing how in-plane exposure unevenness occurs due to the flash light of the camera of another person. FIG. 4 is a flowchart showing a first embodiment of a method for detecting a line-like luminance change. FIG. 5 is a diagram showing a state in which the exposure unevenness due to the flash light of the camera of another person changes in the line direction. FIG. 6 is a diagram showing a luminance difference between lines due to flash light of another person's camera. FIG. 7 is a diagram showing an example of an LCD screen that displays a warning of uneven brightness. FIG. 8 is a flowchart showing a second embodiment of the method for detecting a line-like luminance change. FIG. 9 is a timing chart showing the exposure and readout timings of the three images stored when the shutter release switch is fully pressed, and shows a state in which flash light is incident in the first half of the exposure period of the image to be recorded. FIG. 10 is a timing chart showing the exposure and readout timings of three images stored when the shutter release switch is fully pressed, and shows a state in which flash light is incident in the second half of the exposure period of the image to be recorded. FIG. 11 is a flowchart showing a second embodiment of the imaging control method according to the present invention. FIG. 12 is a flowchart showing a third embodiment of the imaging control method according to the present invention. FIG. 13 is a flowchart showing a fourth embodiment of the imaging control method according to the present invention.

  Embodiments of an imaging apparatus and an imaging control method according to the present invention will be described below with reference to the accompanying drawings.

[Imaging device]
FIG. 1 is a block diagram showing an internal configuration of an imaging apparatus according to the present invention.

  As shown in the figure, the image pickup apparatus (digital camera) 1 mainly includes a central processing unit (CPU) 10, an operation unit 12, a flash light emitting unit 20, a lens unit 22, a CMOS sensor 26, a timing generator (TG) 28, an AGC. The circuit 30 includes an A / D converter 32, an image signal processing circuit 34, a compression / decompression processing circuit 36, an LCD driver 38, a liquid crystal display (LCD) 40, an AE / WB detection circuit 42, a memory card 44, and a media controller 46. ing.

  The CPU 10 performs overall control of the entire digital camera 1 according to a predetermined control program based on an operation signal input from the operation unit 12. In the ROM 16 connected to the CPU 10, a control program for operating the digital camera 1 and various setting information are written, and the CPU 10 controls each unit according to this program.

  Further, the CPU 10 cuts out signals in the AF area (for example, the center of the screen) and integrates absolute value data in the AF area.

  The operation unit 12 includes a shutter release button, a power / mode switch, a mode dial, a zoom key, a cross key, a menu / OK key, a BACK key, and the like.

  The shutter release button instructs various shooting preparation processes such as automatic exposure control (AE control) and automatic focus control (AF control) at the time of half-pressing operation, and in this state the main imaging is performed at the time of full-pressing operation. Is instructed.

  The power / mode switch is operated when the power of the digital camera 1 is switched on / off.

  The mode dial is operated when the operation mode of the digital camera 1 is switched. The operation mode includes a still image (single shooting) shooting mode in which shooting is performed only once, a continuous shooting mode in which a plurality of shootings are continuously performed, and a playback mode in which an image obtained by shooting is played back and displayed on the LCD 40. is there.

  The zoom key is operated when zooming the zoom lens.

  The cross key moves the cursor in the menu screen displayed on the LCD 40.

  The menu / OK key is operated when a menu screen is displayed on the LCD 40 or when a selection content is determined. A desired shooting scene can be set from various shooting scenes (indoor, person, night view, etc.) by operating the menu / OK key, the cross key, and the like. The shooting scene function is a function for automatically setting various shooting conditions according to the set shooting scene. The CPU 10 automatically sets shooting conditions such as an exposure value, shooting sensitivity, white balance control parameters, flash emission, and the like to values suitable for the shooting scene in accordance with the set shooting scene. The setting of the shooting scene may be performed by a function in which the CPU 10 automatically determines the shooting scene and sets the optimum shooting scene (automatic scene recognition).

  The BACK key is operated when returning the menu screen displayed on the LCD 40. The RAM 14 is used as a calculation work area for the CPU 10 and a temporary storage area for image data. The ROM 16 stores a control program executed by the CPU 10, various data necessary for control, various setting information related to the operation of the digital camera 1, and the like. The VRAM 18 temporarily stores image data for displaying a through image.

  The flash light emitting unit 20 irradiates a flash according to the subject brightness when performing shooting.

  The lens unit 22 mainly includes a zoom mechanism and a focus mechanism, and a diaphragm. In response to the operation of the zoom operation key, the zoom mechanism moves the photographing lens 22a to perform zooming. The focus mechanism performs focusing by moving a focus lens incorporated in the photographic lens 22a. The aperture device 22b adjusts the amount of subject light incident on the CMOS image sensor 26 (hereinafter referred to as the CMOS sensor 26) by adjusting the aperture opening. The diaphragm device 22 b is controlled in operation by the CPU 10 via the motor 23.

  The CMOS sensor 26 has a plurality of lines of light-receiving surfaces in which a large number of photosensors are arranged in a matrix, and the subject image formed on the light-receiving surface is an amount corresponding to the amount of incident light by each photosensor. Is converted into a signal charge.

  The electric charge accumulated in each photosensor is converted into a voltage signal by an amplifier for each photosensor, and is output as an analog image signal by a timing signal input from a timing generator (TG) 28.

  Specifically, in the CMOS sensor 26, read lines are sequentially selected by a vertical scanning signal applied from the TG 28 via a vertical scanning circuit. The selected signal for one line is read out to the CDS circuit, where it is held based on the timing signal input from the TG 28 and noise is removed. A signal for one line held in the CDS circuit is sequentially read out to an output line by a horizontal scanning signal applied via a horizontal scanning circuit.

  For the lines selected by the vertical scanning circuit, a reset signal is sequentially applied after signal transfer to reset the charge of the photosensor, and thereafter charge accumulation is started again.

  When the vertical scanning circuit scans from the first line to the last line of the CMOS sensor 26, it returns to the first line again, thereby forming a rolling shutter with a period of one frame. Further, by appropriately setting the readout timing and reset timing of each line, it is possible to set the time (shutter speed) from when the photosensor is reset to when it is read out.

  An AGC (Automatic Gain Control) circuit 30 amplifies the image signal with a gain corresponding to the imaging sensitivity set by the CPU 10 with respect to the image signal output from the CMOS sensor 26 and outputs the amplified image signal to the A / D converter 32. .

  The A / D converter 32 converts the analog signal output from the AGC circuit 30 into, for example, a 12-bit digital signal and outputs it. The digital signal output from the A / D converter 32 is sent to the image signal processing circuit 34.

  The image signal processing circuit 34 includes a synchronization circuit (a processing circuit that converts a color signal into a simultaneous expression by interpolating a spatial shift of the color signal associated with the color filter array of the single-chip CMOS sensor), a white balance correction circuit, a gamma A correction circuit, a contour correction circuit, a luminance / color difference signal generation circuit, and the like are included, and in accordance with a command from the CPU 10, the input image signal is subjected to necessary signal processing to obtain luminance data (Y data) and color difference data (Cr, Cb). Image data (YUV data).

  The compression / decompression processing circuit 36 performs compression processing in a predetermined format on the input image data in accordance with a command from the CPU 10 to generate compressed image data. Further, in accordance with a command from the CPU 10, the input compressed image data is subjected to a decompression process in a predetermined format to generate uncompressed image data.

  The LCD driver 38 performs predetermined signal processing on the image signal generated by the image signal processing circuit 34 and held in the VRAM 18, generates an image display signal, and outputs the signal to the LCD 40 at a fixed timing.

  The LCD 40 is configured by a liquid crystal display capable of color display, and is used as an image display for displaying a photographed image in the reproduction mode and a user interface for performing various setting operations. In the shooting mode, a through image is displayed and used as an electronic viewfinder for checking the angle of view.

  The AE / WB detection circuit 42 divides one screen into a plurality of areas (for example, 16 × 16) as physical quantities necessary for AE control, and R, G, B for each divided area (hereinafter referred to as a photometric division area). The integrated value of the image signal is calculated. The calculated value is output to the image signal processing circuit 34 and used in the white balance correction circuit in the image signal processing circuit 34.

  The media controller 46 controls reading / writing of data with respect to a nonvolatile memory card 44 such as a flash memory loaded in the media slot.

  The operation of the digital camera 1 configured as described above will be described.

[First Embodiment (Exposure unevenness warning)]
FIG. 2 is a flowchart showing the first embodiment of the imaging control method according to the present invention.

  When the shutter release button is fully pressed and the CPU 10 is instructed to take an image for recording, the aperture device 22b and the electronic shutter are controlled to perform exposure control for the main image taking, and from the CMOS sensor 26 the image signal is received. Rolling reading is performed (step S10).

  Subsequently, when the rolling reading of the image signal for one frame for recording is completed, the line-like luminance change in the image of the one frame is detected (step S12).

  FIGS. 3A to 3C show states in which in-plane exposure unevenness occurs due to the flash light of the camera of the other person entering during the exposure of the main imaging.

  In the case of the rolling shutter method, the exposure start time is shifted line by line, and when the flash light of the other person's camera is incident during exposure, the first half, second half, or Exposure unevenness in which the central portion becomes a high luminance region occurs (FIGS. 3A to 3C).

  Note that the uneven exposure shown in FIG. 3C does not occur when the exposure time for one line is longer than the time from the start of reading the first line to the start of reading the last line.

<First Example of Method for Detecting Line-shaped Luminance Change>
FIG. 4 is a flowchart showing a first embodiment of a method for detecting a line-like luminance change.

  Now, assuming that the total number of lines of the CMOS sensor 26 is n, first, a variable i indicating the position of the line is set to 1 (step S100).

Subsequently, the average luminance values E _i and E _{i + 1} of the lines i and _{i + 1} are acquired (step S102). The average luminance value can be obtained by integrating and averaging the image signals for one line that are read out from the CMOS sensor 26 for each line.

Next, the difference between the average luminance values E _i and E _{i + 1} of the preceding and following lines is obtained, and when this difference (E _{i + 1} −E _i ) is larger than the upper threshold value Th1 (E _{i + 1} −E _i > Th1), or the lower limit If it is smaller than the threshold value Th1 (E _{i + 1} −E _i <Th2), the position (line number) of the line i is stored (step S104 to step S110).

  Now, as shown in FIGS. 3A and 3B, when flash light is incident on the first half or the first half of the exposure period of one frame, the luminance average value of each line read by rolling is shown in FIG. As shown in A) and (B), it changes according to the line position, and as shown in FIGS. 6A and 6B, the boundary (between lines) between the line where the flash light is incident and the line where it is not incident is as follows. A large luminance difference occurs.

  Therefore, by detecting the luminance difference exceeding the upper limit threshold Th1 or the lower limit threshold Th2 as described above, it is determined that exposure unevenness due to the flash of the camera of the other party has occurred. If the position of line i is stored in step S108, it is determined that flash light has been received in the latter half of the line position (see FIGS. 5B and 6B), and in step S110. When the position of line i is stored, it is determined that flash light has been received in the first half of the line position (see FIGS. 5A and 6A).

  Subsequently, the variable i is incremented by 1 (step S112), and it is determined whether or not i = n (n: position of the last line) (step S114). If i <n (in the case of “No”), the process returns to step S102, and if i = n (in the case of “Yes”), the process ends.

  Returning to FIG. 2, when the line-like luminance change detection process is completed, whether or not a line-like luminance change has occurred (that is, whether or not the line position where the average luminance between the lines has greatly changed is stored). (Step S14), and if it is determined that a line-like luminance change has occurred, an exposure unevenness warning is issued (step S16).

  For example, as shown in FIG. 7, the exposure unevenness warning displays an image taken on the LCD 40 on the back of the digital camera 1 and a message such as “Exposure unevenness occurred!” On the LCD 40 screen. In addition, a marker M (in this embodiment, a broken line) indicating the line position where the average luminance between the lines has greatly changed is displayed.

  When the exposure unevenness warning is issued, the photographer confirms whether or not the exposure unevenness actually occurs on the screen of the LCD 40, and when the exposure unevenness is detected erroneously or when the exposure unevenness is acceptable. A recording instruction is issued, and if the uneven exposure is not acceptable, a canceling instruction is issued to cancel the image recording process (step S18). The recording instruction can be performed by pressing the menu / OK key of the operation unit 12, and the cancel instruction can be performed by pressing the BACK key of the operation unit 12. These key operation methods are displayed on the screen of the LCD 40.

  If it is determined in step S14 that a line-like luminance change has not occurred, and if a recording instruction is issued in step S18, compression processing of the captured image temporarily held in the RAM 14, Recording processing such as recording on the memory card 44 is performed (step S20).

  The photographer can retake the image by the exposure unevenness warning, thereby recording only an image having no exposure unevenness or an image in which exposure unevenness is acceptable.

  In this embodiment, when the exposure unevenness is warned, the photographer can select image recording / cancellation. However, the present invention is not limited to this, and recording may be performed unconditionally.

<Second Embodiment of Method for Detecting Line-like Luminance Change>
FIG. 8 is a flowchart showing a second embodiment of the method for detecting a line-like luminance change.

  Now, assuming that the total number of lines of the CMOS sensor 26 is n, first, a variable i indicating the position of the line is set to 1 (step S120).

  When this detection method is applied, images of adjacent frames (front and back frames) of one frame image to be recorded are simultaneously acquired, and three images are stored in the RAM 14.

  That is, when the shutter release switch is pressed halfway, exposure and reading are performed by the rolling shutter, and the image held in the RAM 14 is updated with the latest frame image. When the shutter release switch is fully depressed, the frame image is not updated, and the one frame image to be recorded and the next frame image captured immediately after the shutter release are stored in the RAM 14. Thus, the three images are temporarily stored in the RAM 14.

  9 and 10 show the exposure and readout timings of the three images stored when the shutter release switch is fully pressed.

9 and 10, time t ₁ indicates the timing of the internal synchronization signal of the rolling shutter immediately after the shutter release switch is fully pressed, and times t ₀ and t ₂ indicate the frames before and after time t _1. Timing is shown.

Returning to FIG. 8, if these three time-series images are A, B, and C, the luminance average values E _Ai , E _Bi , and E _Ci of the same line i of the images A, B, and C are respectively represented. Obtain (step S122).

Subsequently, the luminance average values E _Ai , E _Bi , and E _Ci are compared, and a line i that satisfies the condition of E _Ai <E _Bi or E _Bi > E _Ci is detected (step S124).

  That is, as shown in FIG. 9, when the flash light is incident in the first half of the exposure period of the image to be recorded, the average luminance value of the line where the exposure is started from the time t1 to the flash light incident timing is the same in the preceding and subsequent frames. It becomes larger than the average luminance value of the line.

  On the other hand, as shown in FIG. 10, when the flash light is incident in the second half of the exposure period of the image to be recorded, the average luminance value from the line at the flash light incident timing to the last line is the average luminance of the same line in the previous and subsequent frames. Larger than the value.

  By comparing the average luminance values of three identical lines as described above, a line having a higher average luminance than the image of the adjacent frame among the lines on the image B is determined as the line on which the flash light is incident, The position (line number) of the line i is stored (step S126).

  Subsequently, the variable i is incremented by 1 (step S128), and it is determined whether i = n (n: position of the last line) or not (step S130). If i <n (“No”), the process returns to step S122.

  When i = n (in the case of “Yes”), the presence / absence of exposure unevenness is determined based on the information stored in step S126, and the high-luminance area is determined when it is determined that exposure unevenness exists. (Step S132).

  For example, if the line position is stored in step S126, it is determined that there is uneven exposure. If the line position is stored continuously, the range of the continuous line position is determined. However, it can be determined as a high luminance region.

In step S124, the brightness average values E _Ai , E _Bi , and E _Ci of the same line i are compared. However, it may be determined whether or not the brightness average values are larger than a certain threshold. Further, if the line numbers stored in step S126 are not continuous, or if they are continuous and there are several lines, they may not be determined as exposure unevenness.

[Second Embodiment (Correction of Exposure Unevenness)]
FIG. 11 is a flowchart showing a second embodiment of the imaging control method according to the present invention. The same steps as those in the first embodiment shown in FIG. 2 are denoted by the same step numbers, and detailed description thereof is omitted.

  In the second embodiment, as described with reference to FIGS. 9 and 10, in synchronization with the shutter release switch being fully pressed, at least one of the image B to be recorded and the images A and C of the frames before and after that is recorded. An image is acquired and temporarily stored in the RAM 14.

  If it is determined in step S14 that a line-like luminance change has occurred, the process proceeds to step S30.

  In step S30, image processing is performed to replace the information of the high luminance area in the image B and the information of the same area of the image of the adjacent frame (in this embodiment, the image C of the immediately subsequent frame).

For example, when the flash light is incident on the exposure period the first half of the image B to be recorded as shown in FIG. 9, the area of the front half portion becomes high luminance region B _1, in the high luminance area B ₁ information and, immediately after performing image processing to replace the information in the same area C ₁ of the image C of the frame.

Similarly, when the flash light in the second half the exposure period of the image B to be recorded as shown in FIG. 10 is incident, although the area of the rear half portion has a higher luminance region B _2, and the high-luminance region B ₂ information, immediately performing image processing for replacing of the image information of the same region C ₂ of the C frames.

  When it is determined that a line-like luminance change has occurred in this way, the information of the high luminance area in the image to be recorded is replaced (corrected) with the information of the same area of the image of the immediately following frame, and the corrected An image is recorded (step S20).

  Note that the same correction as described above may be performed using the image A of the immediately preceding frame instead of the image C of the immediately following frame.

  Further, the image B to be recorded and the images A, B, and C of the images A and C of the frames before and after the image B are used, and the images A and B of the immediately preceding frame are used as images for correction. You may make it select the image C suitably.

As a first example of a selection method, (if the area of the front half portion of the image B has a higher luminance region B ₁₎ when the flash light exposure period the first half of the image B to be recorded as shown in FIG. 9 is incident selects an image C immediately after the frame, the area of the rear half portion of the case (image B flash light is incident has a higher luminance region B ₂ in the second half the exposure period of the image B to be recorded as shown in FIG. 10 In the case), the image A of the immediately preceding frame is selected.

  According to this, the image of the selected frame has no flash light in any region, and for example, it can cope with a case where the flash light emission time is long.

As the second example of the selection method, the area of the front half portion of the case (image B flash light is incident has a higher luminance region B ₁ in the exposure period the first half of the image B to be recorded as shown in FIG. 9 In the case), the average brightness of the corresponding areas A ₁ and C ₁ of the images A and C in the immediately following frame is compared, and the image with the lower average brightness is selected. Also, if the flash light in the second half the exposure period of the image B to be recorded as shown in FIG. 10 is incident (if regions of the second half portion of the image B has a higher luminance region B ₂₎ is immediately after the immediately following frame The average brightness of the corresponding areas A ₂ and C ₂ of the images A and C are compared, and the image with the lower average brightness is selected.

  Further, two corrected images are created using both the images A and C of the immediately following and immediately following frames, respectively, and these are displayed side by side on the LCD 40 or switched to be displayed, and the photographer is allowed to select one of them. You may do it.

  Furthermore, when a moving subject is imaged, rolling distortion occurs, but an image with less influence of rolling distortion may be selected.

[Third Embodiment (Correction of Exposure Unevenness)]
FIG. 12 is a flowchart showing a third embodiment of the imaging control method according to the present invention. In addition, the same step number is attached | subjected to the part which is common in 2nd Embodiment shown in FIG. 2, and the detailed description is abbreviate | omitted.

  The third embodiment is different from the second embodiment in that the processes of step S40 and step S42 are performed instead of the process of step S30 of the second embodiment.

  In step S40, the average luminance value of the same line is calculated from the high luminance area in the image to be recorded and the same area in the image of the immediately subsequent frame.

  In step S42, the luminance value of the line corresponding to the high luminance area of the image to be recorded is corrected so that the average luminance value of the luminance value of the line matches the average luminance value of the corresponding line of the image of the immediately subsequent frame. To do. This correction is performed for each line in the high luminance region.

  When it is determined that a line-like luminance change has occurred in this way, the information of the high luminance area in the image to be recorded is corrected to match the luminance value of the information in the same area of the image of the immediately following frame, The corrected image is recorded (step S20).

  Note that as an image used for correction, which of the images of the immediately preceding and immediately following frames is to be selected can be performed as in the second embodiment.

[Fourth embodiment (warning unevenness warning and correction)]
FIG. 13 is a flowchart showing a fourth embodiment of the imaging control method according to the present invention. Note that the same step numbers are assigned to portions common to the first embodiment and the second embodiment shown in FIGS. 2 and 11, and a detailed description thereof is omitted.

  The fourth embodiment is a combination of the first embodiment and the second embodiment. If it is determined in step S14 that a line-like luminance change has occurred, the process proceeds to step S16. Thus, an exposure unevenness warning is issued as in the first embodiment.

  Then, the image to be recorded is displayed on the LCD 40, and the photographer determines whether or not the exposure unevenness needs to be corrected (step S50). When an exposure unevenness correction instruction is input by the photographer, an image in which the information on the high-intensity area in the image B to be recorded is replaced with the information on the same area in the image of the adjacent frame as in the second embodiment. Processing is performed (step S30).

  On the other hand, if the photographer inputs an instruction not to correct exposure unevenness, the process proceeds to step S20, and an image that is not subjected to correction processing is recorded.

  According to this, when exposure unevenness is erroneously detected, it is possible to prevent an image that has been erroneously corrected from being created and recorded.

  Instead of the correction process in step S30, the correction process in steps S40 and S42 of the third embodiment shown in FIG. 12 may be performed.

[Others]
The method for detecting unevenness of exposure due to flash emission of the camera of another person (detection method for line-like luminance change) is not limited to the first embodiment shown in FIG. 4 and the second embodiment shown in FIG. For example, both may be used together, and it may be determined that exposure unevenness has occurred when both are detected simultaneously, or it may be determined that exposure unevenness has occurred when either is detected.

  The exposure unevenness warning is not limited to the warning display on the LCD 40, but may be a warning by voice or a warning using both voice and characters.

  Furthermore, the present invention can also be applied to a case where an image is taken by flash emission by itself. In this case, it is necessary to control the exposure period of one frame and the light emission timing of the flash so that the flash light is uniformly incident during the exposure period of all lines. In addition, the detection of exposure unevenness by another person's flash light at the time of imaging with self-flash emission can be performed by the method shown in FIG.

  It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Imaging device (digital camera), 10 ... CPU, 12 ... Operation part, 14 ... RAM, 16 ... ROM, 20 ... Flash light emission part, 22 ... Lens unit, 26 ... CMOS sensor, 28 ... Timing generator (TG), 32 ... A / D converter, 34 ... Image signal processing circuit, 36 ... Compression / decompression processing circuit, 40 ... Liquid crystal display (LCD), 44 ... Memory card

Claims (18)

A rolling shutter type imaging device that starts exposure by shifting the exposure start timing for each line, and sequentially reads information on the line from a line where a predetermined exposure time has elapsed, with respect to an imaging device having a plurality of light receiving areas. In
An image of one frame composed of information of a plurality of lines sequentially read out from the image sensor, including one frame image to be recorded synchronized with a shutter release operation, or an image of a frame adjacent to the image. Image acquisition means for acquiring images;
Exposure unevenness detection means for detecting the presence or absence of exposure unevenness due to flash emission of another person included in the acquired one-frame image of the recording target;
When exposure unevenness is detected by the exposure unevenness detection means, exposure unevenness warning means for issuing a warning indicating exposure unevenness,
An imaging apparatus comprising: An internal memory in which an image acquired by the image acquisition means is temporarily recorded;
Image display means;
Display control means for displaying an image recorded in the internal memory on the image display means when a warning is issued by the exposure unevenness warning means;
Recording instruction means for inputting image recording;
A recording unit that records an image recorded in the internal memory on a non-volatile recording medium when a recording instruction for an image for which the image unevenness warning has been issued is input by the recording instruction unit;
The imaging apparatus according to claim 1, further comprising: The exposure unevenness detecting means detects a line position indicating an exposure unevenness boundary parallel to at least the line direction,
The imaging apparatus according to claim 2, wherein the exposure unevenness warning unit displays a marker indicating the detected line position on an image displayed on the image display unit. A rolling shutter type imaging device that starts exposure by shifting the exposure start timing for each line, and sequentially reads information on the line from a line where a predetermined exposure time has elapsed, with respect to an imaging device having a plurality of light receiving areas. In
A one-frame image composed of information of a plurality of lines read from the image sensor, and includes a plurality of frames including a one-frame image to be recorded synchronized with a shutter release operation and an image of a frame adjacent to the image. Image acquisition means for acquiring
Exposure unevenness detection means for detecting the presence or absence of exposure unevenness due to flash emission of another person included in the acquired one-frame image of the recording target;
When exposure unevenness is detected by the exposure unevenness detection means, information on the high brightness area corresponding to the exposure unevenness of the image to be recorded is based on information corresponding to the high brightness area in the image of the adjacent frame. Exposure unevenness correcting means for correcting
An imaging apparatus comprising:   The exposure unevenness correcting unit replaces information on a high brightness area corresponding to the exposure unevenness of the image to be recorded with information corresponding to the high brightness area in the image of the adjacent frame. Item 5. The imaging device according to Item 4.   The exposure unevenness correcting unit is configured to calculate a brightness value of a line corresponding to the high brightness area corresponding to the exposure unevenness of the image to be recorded, and an image of an adjacent frame in which an average brightness value of the line corresponding to the high brightness area is The imaging apparatus according to claim 4, wherein correction is performed so as to match an average luminance value of the same line. When exposure unevenness is detected by the exposure unevenness detection means, exposure unevenness warning means for issuing a warning indicating exposure unevenness,
Image display means;
Display control means for displaying the image to be recorded on the image display means when a warning is issued by the exposure unevenness warning means;
Correction instruction means for inputting an instruction to correct exposure unevenness;
The exposure unevenness correcting means corrects exposure unevenness of the image to be recorded when a correction instruction for an image for which the image unevenness warning has been issued is input by the correction instruction means. The imaging device according to any one of 4 to 6. The exposure unevenness detection unit includes a luminance value calculation unit that calculates an average luminance value for each line or for each of a plurality of lines from the acquired image of one frame to be recorded, and a front-rear direction based on the calculated average luminance value. Luminance change detecting means for detecting a luminance change exceeding a predetermined threshold between lines,
The imaging apparatus according to claim 1, wherein the presence or absence of the exposure unevenness is detected based on the presence or absence of a brightness change detected by the brightness change detection unit. The exposure unevenness detection unit calculates a luminance value calculation unit that calculates an average luminance value for each line or each of a plurality of lines from the plurality of frames of images acquired by the image acquisition unit, and calculates the same line of the images of the plurality of frames. A high-luminance line detection means for detecting a line in which the average luminance value of the line of the image to be recorded is larger than the average luminance value of the line of the adjacent image based on the average luminance value,
9. The imaging apparatus according to claim 1, wherein the presence / absence of the uneven exposure is detected based on the presence / absence of a high luminance line detected by the high luminance line detecting means. The image acquisition means acquires a three-frame image including the one-frame image to be recorded and an image of a frame immediately before and after the image;
The exposure unevenness correction means includes selection means for selecting one of the immediately preceding and immediately following frame images as the adjacent frame image used for correcting the exposure unevenness of the image to be recorded. The imaging apparatus according to claim 4, wherein:   The selection unit includes a calculation unit that calculates an average luminance value of the same region in the immediately preceding and immediately following frame images corresponding to the high luminance region corresponding to the exposure unevenness of the image to be recorded, and the calculation The image pickup apparatus according to claim 10, wherein an image having a low average luminance value is selected from the average luminance values obtained.   The selection unit includes a determination unit that determines whether a high-intensity area corresponding to the exposure unevenness of the image to be recorded is the first half or the second half of the image. The image pickup apparatus according to claim 10, wherein an image of the immediately preceding frame is selected when it is determined that the second half image is selected. A rolling shutter type imaging device that starts exposure by shifting the exposure start timing for each line, and sequentially reads information on the line from a line where a predetermined exposure time has elapsed, with respect to an imaging device having a plurality of light receiving areas. In the imaging control method in
An image of one frame composed of information of a plurality of lines sequentially read out from the image sensor, including one frame image to be recorded synchronized with a shutter release operation, or an image of a frame adjacent to the image. Get an image,
Detecting the presence or absence of uneven exposure caused by the flash emission of the other person included in the acquired one-frame image of the recording target;
An imaging control method characterized by issuing a warning indicating exposure unevenness when the exposure unevenness is detected. When the exposure unevenness is detected, an image to be recorded is displayed on the image display means in which the exposure unevenness is detected,
14. The imaging control method according to claim 13, wherein the recording target image is recorded on a non-volatile recording medium when there is an instruction input for instructing recording of an image from a photographer confirming the display result. A rolling shutter type imaging device that starts exposure by shifting the exposure start timing for each line, and sequentially reads information on the line from a line where a predetermined exposure time has elapsed, with respect to an imaging device having a plurality of light receiving areas. In the imaging control method in
A one-frame image composed of information of a plurality of lines read from the image sensor, and includes a plurality of frames including a one-frame image to be recorded synchronized with a shutter release operation and an image of a frame adjacent to the image. Get
Detecting the presence or absence of uneven exposure caused by the flash emission of the other person included in the acquired one-frame image of the recording target;
When the exposure unevenness is detected, the information on the high brightness area corresponding to the exposure unevenness of the image to be recorded is corrected based on the information corresponding to the high brightness area in the image of the adjacent frame. A characteristic imaging control method.   The correction of the information on the high brightness area corresponding to the exposure unevenness is performed by changing the information on the high brightness area corresponding to the exposure unevenness of the image to be recorded into the information corresponding to the high brightness area in the image of the adjacent frame. The imaging control method according to claim 15, wherein the imaging control method is performed by replacement.   The correction of the information of the high brightness area corresponding to the exposure unevenness is performed by calculating the brightness value of the line corresponding to the high brightness area corresponding to the exposure unevenness of the image to be recorded as the average brightness of the line corresponding to the high brightness area. 16. The imaging control method according to claim 15, wherein the imaging control method is performed by correcting the value so as to match an average luminance value of the same line in the image of the adjacent frame. When the exposure unevenness is detected, a warning indicating the exposure unevenness is generated and the image to be recorded is displayed on the image display means before correcting the information of the high luminance area corresponding to the exposure unevenness of the image to be recorded. Displayed on the
18. The imaging control method according to claim 13, wherein when an instruction to correct exposure unevenness is input, information on a high luminance area corresponding to the exposure unevenness is corrected.

Images