JP2008011226A - Method and device for detecting flicker of imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for detecting a flicker of an imaging apparatus that use an imaging device having an imaging element using a CMOS and can securely detect a flicker under even any photographic condition. <P>SOLUTION: The method uses the imaging apparatus which accumulates electric charges in respective pixels arrayed in a matrix form and reads them out by scanning in pixel row units, divides one-frame image data vertically into a plurality of frames to calculate mean luminances by the frames, finds differences in mean luminance between corresponding frames of successive frame image data, and performs flicker detection for extracting a flicker component to detect whether there is a flicker included in the image data and its frequency. When the flicker detection is performed, the charge accumulation time of the imaging device is made shorter than blinking cycles of a light source which generates the flicker. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention, for example, an image in an individual imaging element, such as an imaging device in which a subject illuminated with a light source whose brightness changes due to a power supply frequency such as a fluorescent lamp is configured with a complementary metal oxide semiconductor (CMOS). The present invention relates to a flicker detection method and apparatus for an image pickup apparatus that can reliably detect flicker generated in an image when an image pickup apparatus that performs accumulation and reading of charge as data by scanning in units of pixel rows is used.

  Conventionally, CCDs (Charge Coupled Devices) and CMOSs (Complementary Metal Oxide Semiconductors) have been used as imaging elements that constitute imaging devices of video cameras and digital cameras. Of these, CMOS-based image sensors can be used in the same manufacturing process as LSIs compared to CCD-based image sensors, making them more mass-productive and providing various functions for each pixel, including amplifiers. The size of the entire circuit can be reduced, and the cost is advantageous. In addition, a single power source with a low voltage is sufficient, and there is an advantage that smear, which is a problem in the CCD, is so small that it can be ignored, and that data can be read at high speed.

  However, an image pickup device using CMOS has a lot of noise, and since the image pickup data from the image pickup device constituting each pixel is taken out separately from the CCD, the timing of performing charge exposure differs for each line at the time of image pickup. At the same time, the image data is read out in time series, and there is a drawback that the accumulation time is shifted by the time required for scanning for each scanning line. Due to this drawback, in an imaging device using CMOS, when a subject moving at high speed is imaged, an image bent in the scanning direction is output, or the illumination frequency of the subject is set to the power frequency such as a fluorescent lamp. When a light source whose brightness changes due to this is used, as shown in an exaggerated manner in FIG.

  This flicker occurs when the fluorescent lamp repeats blinking 100 times per second (in the case of 50 Hz) or 120 times (in the case of 60 Hz) depending on the power supply frequency. For example, the frame rate of the imaging device is set to 15 times / second. Then, this blinking occurs in one frame about 6.7 times at 50 Hz, and 8 times at 60 Hz. If the charge accumulation time in each image sensor is not an integral multiple of the blinking period of this light source, The stripe pattern as shown in FIG. 7 is generated in the image.

  On the other hand, in the CCD, since the charge accumulated at the same time by light irradiation is conveyed to the amplifier using the transfer function as it is, the reading of the entire data is slower than the CMOS, but unevenness of light and dark in the screen. It does not occur, the sensitivity of the CCD itself is higher than that of CMOS, and there is little noise.

  However, for example, in a single-lens reflex digital camera, the size of the sensor can be increased, so that the sensitivity and noise can be easily improved. Furthermore, an image sensor using CMOS can easily realize the continuous shooting function required for a single-lens reflex digital camera or the like due to its high speed, and this is combined with the advantages of the image sensor using CMOS described above. Many recent single-lens reflex digital cameras are equipped with an image sensor using this CMOS. The above-mentioned flicker problem can also be prevented by setting the shutter time, that is, the charge accumulation time of each image pickup device in the CMOS, to a multiple of the interval of light and dark, that is, the blinking cycle of the light source depending on the power supply frequency.

  However, as described above, it is necessary to accurately detect the blinking cycle of the light source caused by the power supply frequency in order to eliminate or make the stripe pattern due to flicker disappear or inconspicuous. Regarding such technology, for example, Patent Document 1 relates to a single-panel television camera using a CCD, but the accumulation time is 1/30 seconds so as not to cause flicker under illumination with flicker such as a fluorescent lamp. Furthermore, when the accumulation time is set to 1/30 seconds in this way, the accumulation time is reduced to prevent the problem that the image is blurred (subject blurring) when a moving car is imaged. It is possible to switch between the frame period and the field period and eliminate the signal level change at the time of switching. Further, the state of the subject being imaged, for example, whether the light quantity is sufficient, whether the flicker is large or small, and the subject The storage time is automatically switched by determining whether there is a lot of movement, and the S / N of the playback image, the amount of flicker, and the dynamic depending on the storage time Zodo performs control such that the best condition, the storage time switching the solid-state imaging device is shown.

  In Patent Document 2, a plurality of flicker detection frames are set by dividing an image in the vertical scanning direction, luminance data is detected for each flicker detection frame, and the front and rear two frames are detected for each flicker detection frame. A method of calculating a flicker frequency by extracting a flicker component by taking a difference from luminance data of one frame is shown. In the flicker detection method disclosed in Patent Document 2, adjustment is made so that the frame rate of the imaging signal and the flicker frequency are not synchronized so that the flicker component does not disappear when the difference between the previous and subsequent frames is taken. .

JP-A 63-20977 JP 2003-189129 A

  However, the accumulation time switching solid-state imaging device disclosed in Patent Document 1 switches the accumulation time between the frame period and the field period depending on the light amount, the amount of flicker, the movement of the subject, the S / N of the reproduced image, etc. In the flicker detection method disclosed in Patent Document 2, there is no description about detecting the flicker frequency only by controlling so that the image becomes the best state. If the image blurring occurs between the frames because the image pickup apparatus is held by the hand without being completely fixed, the flicker component is extracted. Therefore, the two frames before and after each flicker detection frame are extracted. In the process of obtaining the difference from the luminance data, there is a problem that the detection accuracy is lowered and flicker component extraction may not be performed properly.

  Therefore, the present invention provides a flicker detection method and apparatus for an image pickup apparatus that uses an image pickup apparatus having an image pickup element using CMOS and can reliably detect flicker under any shooting conditions. Is an issue.

In order to solve the above problems, a flicker detection method for an imaging apparatus according to the present invention is as follows.
An image pickup apparatus including an image pickup device that performs charge accumulation and readout to each pixel arranged in a matrix by scanning in units of pixel rows, and calculates a difference in accumulated charge amount between a plurality of temporally continuous frames. In the flicker detection method of the imaging apparatus for detecting the flicker component generated under the blinking light source,
The flicker is detected by making the charge accumulation time in the plurality of frames for flicker detection shorter than the blinking cycle of the light source.

In addition, the flicker detection device of the imaging device that implements this method is:
Each pixel is arranged in a matrix, and an imaging device including an imaging device that performs charge accumulation and readout by scanning in units of pixel rows, and the presence / absence and frequency of flicker included in image data from the imaging device are detected. In the flicker detection state of the imaging apparatus including a flicker detection unit that detects a flicker component generated under a blinking light source by taking a difference in accumulated charge amount between a plurality of temporally continuous frames in a flicker detection state.
In the flicker detection state, there is provided control means for sending an instruction to the image pickup apparatus to make the charge accumulation time in the plurality of frames shorter than the blinking cycle of the light source.

  Thus, in detecting flicker, by making the charge accumulation time shorter than the blinking cycle of the light source that causes flicker, the data of the captured image becomes data that remarkably reflects the light and darkness caused by the flicker of the light source, and the flicker is higher. In addition to being able to detect with accuracy, the charge accumulation time is shortened, so that subject blur and camera shake have less influence on image data, and flicker detection can be performed more effectively.

  Then, the difference in accumulated charge amount between the plurality of temporally continuous frames is calculated by dividing the frame into a plurality of frames in the vertical direction and calculating an average luminance for each frame, and corresponding to the temporally continuous frames. By configuring the flicker detection method and apparatus so as to calculate the difference between the average luminance of the frames to be calculated, data that significantly reflects the flicker can be obtained, and flicker can be detected with higher accuracy.

  Further, by configuring the flicker detection method and apparatus so as to detect flicker by increasing the imaging frame rate in the imaging apparatus at the time of detecting the flicker, the influence on the image data of subject blur and camera shake is further reduced. Flicker detection can be performed with high accuracy.

  Further, the flicker detection is performed by periodically checking the brightness of the subject and configuring the flicker detection method and apparatus so as to be performed when the brightness of the subject falls below a predetermined value. When image data from an imaging device or a photometric sensor provided separately is used as a detection means, and the output of the subject, that is, the brightness of the subject, that is, the illuminance is clearly larger than the illuminance of a general fluorescent lamp (about 300 Lux to 700 Lux) If the judgment is made, it is possible to prevent false detection by judging that it is outdoors and not performing flicker detection.

  The flicker detection method and apparatus are configured so that the frames acquired for flicker detection are not used for display or storage, so that when the flicker is detected, the charge accumulation time is shorter than usual and the amplification gain of the image data is increased. As a result, the noise increases accordingly, but it is possible to prevent deterioration of the image quality by not using it for display or storage.

  Further, at the time of detecting the flicker, the flicker detection method and apparatus are configured to increase the amplification gain of the image data from the image sensor corresponding to the charge accumulation time in the image sensor that is shorter than the blinking cycle of the light source causing the flicker. By doing so, flicker can be easily detected.

  According to the present invention, the flicker component detection accuracy can be improved and flicker can be reliably detected without adding any special device.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples.

  FIG. 1 is a block diagram showing a schematic configuration of an embodiment of an imaging apparatus having a flicker detection apparatus according to the present invention. Reference numeral 10 in the figure uses a CMOS as an image sensor, and has a gain amplifier that amplifies an output signal from the image sensor, an A / D converter that converts an analog image signal into a digital image signal, and the like. 11 is an image processing unit that performs operations such as color adjustment, gamma correction, and luminance signal generation on the image signal from the imaging unit 10, and 12 has a light amount change caused by the power source frequency of the subject. This flicker detection unit 12 detects flicker generated by illumination with a light source. The flicker detection unit 12 takes an image signal of one frame in order to take a difference in accumulated charge amount between a plurality of consecutive frames as will be described later. Dividing into multiple frames in the vertical direction, calculating the average brightness for each frame, and taking the difference of the average brightness of the corresponding frames in consecutive frames. Degrees and the difference calculation means, and a like storage device. In addition to detecting flicker, the brightness of the subject is detected using a luminance signal in the image signal sent from the imaging unit 10 or using a photometric sensor provided separately, and the brightness, that is, the illuminance is generally When it is determined that the illuminance of a typical fluorescent lamp is clearly larger than the illuminance (about 300 Lux to 700 Lux), it is determined that the illumination is outside and flicker detection is not performed. 13 also has a function of outputting a signal to that effect.

  13 controls the image pickup unit 10 with an image pickup unit control signal 18 and receives a signal from the flicker detection unit 12 indicating that the brightness is below a predetermined value. Flicker detection for performing determination is instructed to the imaging unit 10 and the flicker detection unit 12, and based on the evaluation value from the flicker detection unit 12, the presence / absence of flicker and the flicker frequency are determined, and image data is stored. System control unit having a CPU for controlling the image memory 16 and the image display unit 17 such as an LCD, etc. 14 has a key switch, a dial, etc., and image data captured when flicker detection is not performed A mode in which the flicker detection unit 12 is passed and the through image is displayed on the image display unit 17 or recorded in the image memory 16. Operation unit having means such as for, 15 is a memory bus.

  In a normal state in which flicker detection is not performed, the image pickup apparatus having the flicker detection device according to the present invention amplifies an image signal from the image pickup element by a gain amplifier in the image pickup unit 10 in accordance with an instruction from the system control unit 13. The analog image signal is converted into a digital image signal by an A / D converter, and the image processing unit 11 performs operations such as color adjustment, gamma correction, and luminance signal generation. Since no flicker detection instruction signal is received from the system control unit 13 to the flicker detection unit 12, the flicker detection unit 12 does not perform any processing and sends the image signal to the image display unit 17 via the memory bus 15. Send and display. When the operation unit 14 instructs the system control unit 13 to store the image data in the image memory 16, the instruction is sent to the image memory 16 to store the image signal.

  In the imaging apparatus configured as described above, the brightness of the subject may fall below a predetermined value and flicker may occur as described above, because the subject is illuminated with a light source having a light amount change caused by a power frequency or the like. If it is determined that there is a flicker, the presence / absence of flicker and the flicker frequency are determined.

  2A and 2B are diagrams for explaining the outline of flicker detection by the flicker detection unit 12. FIG. 2A shows a state in which image data for one frame is divided when flicker detection is performed, and FIG. A diagram showing the average value of the luminance signal in each frame divided as in A), (C) a diagram showing a band-pass filter (BPF) for detecting the flicker frequency, and FIG. It is a flowchart of a flicker detection method. FIGS. 4 to 6 are diagrams for explaining the flicker detection method of the present invention. FIG. 4 is a striped pattern generated by flicker on an image by shortening the charge accumulation time in an image sensor using a CMOS. In FIG. 5, a frame with an increased frame rate is inserted between normal frames to detect flicker periodically, and an image captured in that frame is used as a through image. FIG. 6 is a diagram showing a state of a striped pattern generated by flicker when the charge accumulation time is not shortened and the frame rate is not increased.

  In the flicker detection method in the imaging apparatus according to the present invention, the system control unit 13 instructs the flicker detection unit 12 to perform flicker detection according to the flow shown in FIG. 3 periodically (for example, every 5 seconds or 10 seconds). Is issued. When this process is started in step S61 of FIG. 3 according to the instruction, first, in step S62, the brightness of the subject is detected by the luminance signal in the image signal sent from the imaging unit 10 by the flicker detection unit 12 or by a separately provided photometric sensor. The system control unit 13 receiving the signal determines whether or not the brightness is below a predetermined value in step S63. If not, it is determined that it is not necessary to detect flicker, and the process goes to step S76 to end the process.

  The reason why the flicker detection execution instruction is issued once every 5 to 10 seconds, for example, is that the light source that illuminates the subject may change. The reason for detecting whether or not to perform flicker detection by detecting the brightness of the subject is to prevent false detection by performing unnecessary flicker detection. In this way, instead of determining whether or not to detect the brightness of the subject, the system control unit 13 may always execute when flicker detection is instructed.

  If it is determined in step S63 that the brightness is equal to or less than the specified value, the process proceeds to step S64 to prepare for flicker detection. That is, the system control unit 13 first uses the flicker detection unit 12 to detect one frame of image data sent from the imaging unit 10 via the image processing unit 11, as shown in FIG. 0], detection frame [1],..., And detection frame [15] are equally divided in the vertical direction. The number of divisions of image data for one frame is set so that the total time required for scanning within each frame is shorter than the light source blinking cycle to be detected. That is, as described above, for example, if the frame rate of the imaging unit is set to 15 times / second, this blinking occurs approximately 6.7 times in the case of 50 Hz and 8 times in the case of 60 Hz in one frame. In order to make the luminance part and the maximum luminance part separate frames, it is necessary to make at least 16 divisions or more. A larger number of frame divisions is advantageous for frequency detection accuracy, but the calculation processing load increases, and is determined in consideration of this point. In the following description, a case where image data for one frame is divided into 16 as an example will be described as an example. However, this is not limited to 16 divisions. It is obvious that it is good.

  Next, in step S65, the system control unit 13 sets the charge accumulation time of the image pickup device using the CMOS constituting the image pickup unit 10 to a value that clearly shows the light and darkness caused by flicker, as indicated by 33 in FIG. And instructing the increase in the gain of the amplifier included in the imaging unit 10 to compensate for the decrease in the accumulated charge amount. In FIG. 4, 31 is a vertical synchronizing signal, 32 shows the change in brightness of the light source depending on the power supply frequency, and 33 shows each black line for each horizontal line of the image sensor using CMOS. The length of charge accumulation time 34 indicates the light and darkness caused by flicker generated by the captured image data. In FIG. 5 and FIG. 6 described below, the same reference numerals as those described above are the same.

  As can be seen from FIG. 4, in the flicker detection process, the shorter the charge accumulation time 33 of the image sensor using the CMOS that constitutes the imaging unit 10, the greater the relative ratio of the integrated light quantity between the horizontal elements. In this case, as shown at 34, data in which the brightness change due to flicker appears remarkably is obtained, and therefore the accuracy of flicker detection is increased. In addition, since the charge accumulation time 33 is shortened, the influence of the image data on the subject blur and camera shake is reduced, and flicker detection can be performed more effectively.

  On the other hand, as shown in FIG. 6, when the charge accumulation time of the image pickup device using the CMOS constituting the image pickup unit 10 is made longer than the light source brightness change period 32 by 51, each device becomes a subject. Since the image data obtained by integrating the brightness changed due to the flicker in the image is obtained, the average value of the brightness change of the light source that illuminates the subject is recorded as the obtained image data. The effect on the image due to is relatively small. Therefore, in this case, flicker detection becomes difficult.

Returning to FIG. 3 again, in step S66, the system control unit 13 instructs the imaging unit 10 to increase the frame rate as shown in FIG. 5 in order to facilitate flicker detection. In the case of FIG. 5, also enter the vertical synchronizing signal is time t ₃ and t intermediate t ₄ of ₅ shown in 31, two frames of the image during the time a normal one frame interval t ₃ and t ₅ To get. This reduces the time difference between frames, reduces the probability and influence of subject blur and camera shake, and improves flicker detection accuracy. Although the flicker detection frame rate shown in FIG. 5 is twice the normal frame rate, this is merely an example, and it is obvious that a higher rate may be set.

  In step S66, the system control unit 13 sets the frame rate for performing the flicker detection to a frame rate at which the position where the light and dark stripes due to the flicker appear on the screen differs for each frame (frames for 1 second). The signal is sent to the imaging unit 10 via the imaging unit control signal 18.

  In addition, since the shortened charge accumulation time for flicker detection indicated by 33 and 43 in FIGS. 4 and 5 reduces the image data output as described above, the gain amplifier included in the imaging unit 10 is used to compensate for this. Increase the gain. However, in this case, the frame with the increased gain also increases noise, and since this frame is an image in which flicker is intentionally emphasized, the image data during this period is displayed in accordance with an instruction from the system control unit 13. 17 is not displayed or stored in the image memory 16. By this processing, when flicker is detected, the frame rate of image display is periodically decreased (for example, every 5 seconds), but it is considered that there is no obstacle in practical use from the ratio of the number of frames to be dropped.

Reference numeral 42 in FIG. 5 shows a state during this period, and the image data captured in the normal charge accumulation time as indicated by 41 is updated (N) at a normal frame rate without flicker detection. , Update (N + 1), update (N + 2), the data is updated between times t ₁ and t ₂ , between times t ₂ and t ₃ , and between times t ₃ and t _5. 17 or storage in the image memory 16, but when flicker is detected between times t ₃ and t ₅ at 31, the gain accumulation gain is reduced in a short time as indicated by 43. since the raised, during this period of the data is used only in the flicker detection, between times t ₅ and t ₆ of 42, as between the times t ₆ and t _7, update (N + 2) is held as it is an image Display on display unit 17 Indicates that storage into the image memory 16 is performed.

  In addition, by increasing the frame rate as shown in FIG. 5, the charge accumulation time of the image sensor using the CMOS that constitutes the imaging unit 10 is shortened according to the frame rate, but the charge accumulation time is further shortened. You may do it. In this way, as described above, the influence of subject shake and camera shake on the image data is reduced, and flicker detection can be performed with higher accuracy.

  Returning to FIG. 3 again, next, the system control unit 13 instructs the flicker detection unit 12 in step S67, and the image data for one frame sent from the imaging unit 10 via the image processing unit 11 is displayed in FIG. As shown in FIG. 2A, the detection frame [0], the detection frame [1],..., The detection frame [15] are equally divided in the vertical direction, and the average value of the luminance signal in each frame is shown in FIG. B) is calculated and stored as indicated by Y [0], Y [1],..., Y [15].

  In the next step S68, the system control unit 13 causes the flicker detection unit 12 to acquire the next frame and similarly divides it into the detection frame [0], the detection frame [1],..., And the detection frame [15]. In addition, the average value of the luminance signal in each frame is calculated as indicated by Y [0], Y [1],..., Y [15] in FIG. Then, the difference from the average value of the luminance signal of the first frame stored previously is calculated.

  This difference calculation process is for erasing the subject data included in the image data and extracting only the light and dark stripe pattern (flicker component) due to flicker. At this time, as described above, the flicker appearing positions in the two frames that take the difference are made different. This is because only the light and dark due to the flicker remains when the difference is taken. If the frame rate and the flicker frequency (the fluorescent lamp power supply frequency) are synchronized, the position where the flicker occurs is fixed on the screen, and the flicker component disappears when the difference is taken. The frame rate that is synchronized with the flicker frequency is a value obtained by dividing the power supply frequency of the fluorescent lamp by a positive integer or a value obtained by multiplying the positive integer by a positive integer. For example, when the power supply frequency is 50 Hz, 100 frames / second, 50 frames / second, In the case of 60 Hz, 120 frames / second, 60 frames / second, 30 frames / second,... Therefore, in order to avoid this, the system control unit 13 performs an operation to make the horizontal synchronization period longer or shorter so that the frame rate becomes a value slower or faster than a value synchronized with the flicker frequency. To flicker the flicker component.

  When the flicker component is extracted in this way, the system control unit 13 uses the luminance signal average values indicated by Y [0], Y [1],..., Y [15] in FIG. In step S70, the signal is input to the luminance signal average value input terminal 21 in the band-pass filter shown in FIG. The band-pass filters 22 and 23 are for detecting the power supply frequency of the light source that illuminates the subject that causes flicker. Since the brightness of the light source changes in a cycle that is twice the power supply frequency, 22 is set to 100 Hz. Correspondingly, 23 is provided corresponding to 120 Hz.

  Therefore, since the band-pass filters 22 and 23 output a wave having a frequency corresponding to the frequency of the input luminance signal average value, the system control unit 13 performs step S71 based on the output from the output terminals 24 and 25. Then, the presence / absence of flicker and the frequency are determined. In step S72, if there is no flicker, the system control unit 13 advances the process to step S74 to reset the charge accumulation time of the image sensor to the value before setting for flicker detection. In step S73, based on the flicker frequency detected, the charge accumulation time (shutter time) of the image pickup device using the CMOS in the image pickup unit 10 is set to a flicker corresponding accumulation time that is an integral multiple of the flicker interval in FIG. The imaging unit control signal 18 is sent to the imaging unit 10. In step S75, the frame rate of the imaging unit 10 is reset to the value before the flicker detection setting, and the process ends in step S76.

  Note that the presence / absence of flicker and the frequency may be determined based on the average luminance signal value shown in FIG. That is, flicker can be determined to be flicker when there is a difference in the luminance signal average value of each frame shown in FIG. 2 (B). Next, it is compared with the next to the luminance signal average value of all the frames, and it is determined that there is flicker when a difference in brightness occurs at a constant interval. Further, the flicker frequency is determined by the interval. calculate. In other words, as described above, if the frame rate of the imaging unit is 15 times / second, this blinking will occur approximately 6.7 times in the case of 50 Hz and 8 times in the case of 60 Hz in one frame. When 16 is set to 16, a dark portion or a bright portion comes every two or three in the case of 50 Hz, and every two in the case of 60 Hz.

  Thus, in detecting flicker, by making the charge accumulation time shorter than the blinking cycle of the light source that causes flicker, the data of the captured image becomes data that remarkably reflects the light and darkness caused by the flicker of the light source, and the flicker is higher. In addition to being able to detect with accuracy, the charge accumulation time has been shortened and the frame rate has been increased, so subject blur and camera shake are less affected by image data, and flicker detection is performed more effectively. be able to.

  According to the present invention, flicker can be detected with high accuracy even using an image pickup device having an image pickup element using CMOS, and therefore an image pickup device capable of obtaining an image with reduced occurrence of flicker can be provided. .

It is a block diagram which shows schematic structure of one Embodiment of the imaging device which becomes this invention. FIGS. 4A and 4B are diagrams for explaining an outline of flicker detection by the flicker detection unit 12, in which FIG. 5A shows a state in which image data for one frame is divided when performing flicker detection, and FIG. The figure which showed the average value of the luminance signal in each frame divided | segmented in this way, (C) is the figure which showed the band pass filter (BPF) for detecting the frequency of a flicker. It is a flowchart of the flicker detection method of this invention. It is a figure for demonstrating the flicker detection method of this invention, and is a case where the charge accumulation time in the image pick-up element using CMOS is shortened, and the stripe pattern produced by flicker appears clearly on an image. FIG. 4 is a diagram for explaining the flicker detection method of the present invention, in which a frame with an increased frame rate is periodically inserted between normal frames to detect flicker, and an image captured in that frame is a through image. It is a figure for demonstrating not using as. FIG. 5 is a diagram showing a state of a stripe pattern caused by flicker when the charge accumulation time is not shortened and the frame rate is not increased. It is a figure which exaggerated and showed the flicker which arises by using CMOS as an image pick-up element, and using the light source from which brightness changes according to a power supply frequency for illumination of a to-be-photographed object.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image pick-up part 11 Image processing part 12 Flicker detection part 13 System control part 14 Operation part 15 Memory bus 16 Image memory 17 Image display part 18 Image pick-up part control signal 20 Image signal 21 of 1 frame Luminance signal average value input terminal 22 Corresponding to 100 Hz Bandpass filter 23 Bandpass filters 24 and 25 corresponding to 120 Hz Output terminal for detection output

Claims (12)

An image pickup apparatus including an image pickup device that performs charge accumulation and readout to each pixel arranged in a matrix by scanning in units of pixel rows, and calculates a difference in accumulated charge amount between a plurality of temporally continuous frames. In the flicker detection method of the imaging apparatus for detecting the flicker component generated under the blinking light source,
A flicker detection method for an imaging apparatus, wherein a flicker is detected by setting a charge accumulation time in the plurality of frames for flicker detection to be shorter than a blinking cycle of the light source.   The difference in accumulated charge amount between the plurality of temporally consecutive frames is calculated by dividing the frame into a plurality of frames in the vertical direction and calculating an average luminance for each frame, and corresponding frames in the temporally consecutive frames. The flicker detection method for an image pickup apparatus according to claim 1, wherein the calculation is performed by taking a difference from the average luminance of the image pickup apparatus.   3. The flicker detection method for an image pickup apparatus according to claim 1, wherein the flicker is detected by increasing an image pickup frame rate in the image pickup apparatus when the flicker is detected.   The imaging according to any one of claims 1 to 3, wherein the flicker detection is performed when the brightness of the subject is periodically checked and the brightness of the subject falls below a predetermined value. Device flicker detection method.   5. The flicker detection method for an imaging apparatus according to claim 1, wherein the frame acquired for flicker detection is not used for display or storage.   6. When the flicker is detected, an amplification gain of image data from the image sensor is increased in accordance with a charge accumulation time in the image sensor that is shorter than a blinking period of a light source that causes the flicker. The flicker detection method of the imaging device described in any of the above. Each pixel is arranged in a matrix, and an imaging device including an imaging device that performs charge accumulation and readout by scanning in units of pixel rows, and the presence / absence and frequency of flicker included in image data from the imaging device are detected. In the flicker detection state of the imaging apparatus, which includes a flicker detection unit that detects a flicker component generated under a blinking light source by taking a difference in accumulated charge amount between a plurality of temporally continuous frames in a flicker detection state.
A flicker detection apparatus for an image pickup apparatus, comprising: control means for sending, to the image pickup apparatus, an instruction to make the charge accumulation time in the plurality of frames shorter than a blinking cycle of a light source in the flicker detection state.   The flicker detection device stores storage means for storing the average brightness for each frame calculated by dividing the frame into a plurality of frames in the vertical direction, and calculates the average brightness for each frame and the time stored in the storage means. The calculation means for calculating the difference of the accumulated charge amount by taking the difference from the average luminance of the corresponding frames in consecutive frames, and extracting the flicker component. Flicker detection device for imaging device.   9. The flicker detection apparatus for an imaging apparatus according to claim 7, wherein the control means sends an instruction for increasing an imaging frame rate in the imaging apparatus to the imaging apparatus in the flicker detection state.   The flicker detection unit has brightness detection means for periodically checking the brightness of the subject, and the control means outputs a signal that the brightness of the subject has fallen below a predetermined value by the brightness detection means. The flicker detection apparatus for an image pickup apparatus according to claim 7, wherein flicker detection is instructed to the image pickup apparatus and the flicker detection unit.   11. The flicker detection apparatus for an image pickup apparatus according to claim 7, wherein the control means gives an instruction not to display or store the frame acquired in the flicker detection state.   In the flicker detection state, the control unit instructs the imaging apparatus to increase the amplification gain of the image data from the imaging element in correspondence with the charge accumulation time in the imaging element that is shorter than the blinking cycle of the light source causing the flicker. The flicker detection apparatus for an imaging apparatus according to claim 7, wherein the flicker detection apparatus is used.

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