KR20090098498A - Method for determining flicker frequency due to the environmental lighting condition, digital photographing apparatus enabling to prosecute the method, and recording medium storing program to implement the method - Google Patents

Abstract

A method for determining a flicker frequency by an environment in which a digital photographing device having an image pickup device is used, the digital photographing device for executing the method and a recording medium in which a program for executing the method is stored are provided to prevent the distortion of an image by quickly determining the flicker frequency although a lighting condition is changed. A method for determining a flicker frequency by an environment in which a digital photographing device having an image pickup device is used comprises the following steps of: obtaining data about two frame images in a plurality of sampling areas of an image pickup device(S10); obtaining difference image data about an difference image between two frame images in each sampling area(S20); and then determining the flicker frequency from the difference image data in each sampling area(S30).

Description

Method for determining flicker frequency according to an environment in which a digital photographing apparatus having an image pickup device is used, a digital photographing apparatus capable of performing the method, and a recording medium storing a program for executing the method (Method for determining flicker frequency due to the environmental lighting condition, digital photographing apparatus enabling to prosecute the method, and recording medium storing program to implement the method}

The present invention relates to a method for determining flicker frequency according to an environment in which a digital photographing apparatus having an image pickup device is used, a digital photographing apparatus capable of executing the method, and a recording medium storing a program for executing the method. More specifically, a method of determining the flicker frequency according to the environment in which a digital photographing apparatus having an image pickup device with an image capturing device is simply and automatically used at high speed even when lighting conditions change, and a digital photographing apparatus capable of executing the method and the method A recording medium storing a program for executing the program.

In general, a digital photographing apparatus obtains data on an image from light incident on an image pickup device and displays the image on a display unit or stores the image on a display medium. Of course, the image is displayed on the display unit using the data stored in the storage medium. Here, the image includes a moving image in addition to a still image.

Such a digital photographing apparatus may display a real-time video image from the light incident on the image pickup device in a shooting mode for capturing a still image, and display the real-time video image from the light incident on the image pickup device in the recording mode for capturing a video image. The video image is also displayed on the display unit. Of course, in the latter case, data about a real-time video image from light incident on the image pickup device may be stored in a storage medium.

As such, when displaying a real-time video image on a display unit or storing data for a real-time video image on a storage medium, flicker due to the environment in which the digital photographing apparatus is used appears on the displayed video image or the video image stored on the storage medium. There is a problem that the data for the data becomes data for a moving image having flicker. For example, if the environment where the digital photographing apparatus is located is under fluorescent lighting when displaying a real-time video image on a display unit or storing data for a real-time video image on a storage medium, since the light intensity varies at a constant cycle, the digital photographing apparatus may be used. There has been a problem that flicker due to the environment used is displayed on the video image displayed or data on the video image stored in the storage medium becomes data on the video image having flicker.

In order to solve this problem, it has been proposed to remove flicker of a specific frequency, but because the flicker frequency is different for each region, a digital photographing apparatus set to remove flicker of a certain one frequency may be used in an area having flicker of different frequencies. There was a problem that no effect. In addition, there was a problem that the user should investigate all frequencies causing flicker in each region individually.

The present invention is to solve the various problems including the above problems, a method for determining the flicker frequency by the environment in which a digital photographing apparatus having an image pickup device is simply and automatically used at high speed even if the lighting conditions change, An object of the present invention is to provide a digital photographing apparatus capable of carrying out this method and a recording medium storing a program for executing the method.

The present invention relates to a method for determining a flicker frequency according to an environment in which a digital photographing apparatus having an imaging device is used, the method comprising: (a) acquiring data for two frame images in a plurality of sampling regions of the imaging device; And (b) acquiring differential image data for a differential image that is a difference between the two frame images in each sampling region of the imaging device, and (c) flickering from the differential image data in each sampling region of the imaging device. Determining a frequency, and (d) determining the flicker frequency according to the environment in which the digital photographing apparatus is used, from the flicker frequencies obtained in the plurality of sampling regions of the imaging device. to provide.

According to another aspect of the present invention, the two frame images in the step (a) may be a continuous frame image.

According to another feature of the invention, the step (b), (b1) in each column of each sampling area of the image pickup device, the sum, average or the sum of the data from the pixels belonging to each column in each frame image Obtaining a first value that is a processed value, and (b2) acquiring difference image data for a difference image that is a difference between mutually corresponding first values in the two frame images in each sampling area of the image pickup device. It can be included.

According to another feature of the invention, the step (c) comprises the steps of (c1) determining the flicker frequency in each column from the differential image data in each sampling area of the imaging device, and (c2) In each sampling area, determining the maximum value of the flicker frequencies in each column as the flicker frequency in the corresponding sampling area.

The present invention also provides a recording medium storing a program for executing such a method.

The present invention also provides an image pickup device for generating image data from incident light, a differential image data acquisition unit for obtaining differential image data for a differential image that is a difference between two frame images obtained from the image pickup device, and obtaining the differential image data. A flicker frequency determination unit for determining a flicker frequency from differential image data obtained by a unit is provided.

According to another aspect of the present invention, the image pickup device obtains data for two frame images in a plurality of sampling areas, and the differential image data acquisition unit obtains differential image data in each sampling area of the image pickup device. The flicker frequency determiner determines flicker frequencies from the differential image data obtained by the differential image data acquisition unit in each sampling area of the image pickup device, and determines a flicker frequency from an environment in which a digital photographing apparatus is used from a plurality of flicker frequencies. You can decide.

According to still another aspect of the present invention, the differential image data acquisition unit is a sum, an average, or a value obtained by processing the data from pixels belonging to each column in each frame image in each column of each sampling area of the imaging device. One value may be obtained and differential image data which is a difference between first values corresponding to two frame images in each sampling area of the imaging device may be obtained.

According to another aspect of the present invention, the flicker frequency determiner determines the flicker frequency in each column from the differential image data obtained by the differential image data acquisition unit in each sampling area of the imaging device, The maximum value of the flicker frequencies in each column in the sampling area may be determined as the flicker frequency in the corresponding sampling area, and the flicker frequency due to the environment in which the digital photographing apparatus is used may be determined from the plurality of flicker frequencies.

A method of determining the flicker frequency according to the environment in which the digital photographing apparatus having the image pickup device of the present invention made as described above is used, a digital photographing apparatus capable of executing the method, and a recording medium storing a program for executing the method. According to the present invention, it is possible to prevent distortion of an image by automatically determining a flicker frequency due to an environment in which a digital photographing apparatus is used at high speed, even if the lighting conditions change.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically showing a digital photographing apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram schematically showing a part of FIG. 1.

The overall operation of the digital photographing apparatus is integrated by the CPU 100. In addition, the digital photographing apparatus includes an operation unit 200 including a key for generating an electrical signal from a user. The electrical signal from the operation unit 200 is transmitted to the CPU 100 so that the CPU 100 can control the digital photographing apparatus according to the electrical signal.

In the photographing mode, as the electrical signal from the user is applied to the CPU 100, the CPU 100 detects the signal and controls the lens driver 11, the aperture driver 21, and the imaging device controller 31. Accordingly, the position of the lens 10, the opening degree of the diaphragm 20, the sensitivity of the imaging device 30, and the like are respectively controlled. The imaging device 30 generates data regarding an image from the input light, and the analog / digital converter 40 converts analog data output from the imaging device 30 into digital data. Of course, the analog / digital converter 40 may not be necessary depending on the characteristics of the imaging device 30.

Data from the image pickup device 30 may be input to the digital signal processing unit 50 via the memory 60, or may be input to the digital signal processing unit 50 without passing through the memory 60. It may also be input to 100. The memory 60 is a concept including a ROM or a RAM. The digital signal processor 50 may perform digital signal processing such as gamma correction and white balance adjustment, if necessary. Also, as shown in FIG. 2, the digital signal processor 50 may have other components such as the differential image data acquirer 52 and the flicker frequency determiner 54. Of course, the differential image data acquisition unit 52 and the flicker frequency determiner 54 may be various components, such as components other than the components in the digital signal processor 50. That is, it is sufficient if the digital photographing apparatus according to the present embodiment includes the differential image data acquisition unit 52 and the flicker frequency determination unit 54. The operation of the differential image data acquisition unit 52 and the flicker frequency determination unit 54 will be described later.

The image data output from the digital signal processor 50 is transmitted to the display controller 81 through the memory 60 or directly. The display controller 81 controls the display 80 to display an image on the display 80. The image data output from the digital signal processing unit 50 is inputted through the memory 60 or directly to the storage / reading control unit 71. The storage / reading control unit 71 automatically or according to a signal from a user. The image data is stored in the storage medium 70. Of course, the storage / reading control unit 71 reads data related to the image from the image file stored in the storage medium 70 and inputs the data regarding the image to the display control unit 81 through the memory 60 or through another path. 80 may be displayed. The storage medium 70 may be detachable or may be permanently mounted to the digital photographing apparatus.

Such a digital photographing apparatus may display a real-time video image from the light incident on the image pickup device in a shooting mode for capturing a still image, and display the real-time video image from the light incident on the image pickup device in the recording mode for capturing a video image. The video image is also displayed on the display unit. Of course, in the latter case, data about a real-time video image from light incident on the image pickup device may be stored in a storage medium. When the real-time video image is displayed on the display unit or the data for the real-time video image is stored in the storage medium as described above, the digital photographing apparatus according to the present embodiment appears in the video image on which flicker is displayed due to the environment in which the digital photographing apparatus is used. Alternatively, the data for the moving image stored in the storage medium is prevented from becoming the data for the moving image having flicker.

Specifically, first, two frame images are obtained from the image pickup device 30. Preferably these two frame images may be consecutive frame images. Since these two frame images are for the same subject, the difference between the two frame images is due to the environment in which the digital photographing apparatus is located. For example, if the environment in which the digital photographing apparatus is located is an environment in which a fluorescent lamp is illuminated, the difference in the two frame images is the difference in the light intensity of the fluorescent lamp since the fluorescent light varies in a constant period. Therefore, the differential image data acquisition unit 52 of the digital photographing apparatus according to the present exemplary embodiment obtains differential image data of a differential image, which is a difference between two frame images. As a result, the differential image data obtained by the differential image data acquisition unit 52 has data about an environment in which the digital photographing apparatus is located, specifically, a degree of change in illumination of the digital photographing apparatus.

Therefore, in the digital photographing apparatus according to the present exemplary embodiment, the flicker frequency determiner 54 determines the flicker frequency from the differential image data acquired by the differential image data acquisition unit 52. Through this, it is possible to know the flicker frequency, that is, the frequency of change in the intensity of illumination of the place where the digital photographing apparatus is located. After that, by displaying the real-time video image on the display or excluding data of the flicker frequency component when storing the data for the real-time video image on the storage medium, the high-quality real-time video image without flicker is displayed on the display, Data on clear, high-quality, real-time video images without flicker can be stored on storage media. Excluding the data of the flicker frequency components may be performed using various methods, for example, a bandpass filter may be used to filter out components corresponding to a specific frequency.

The flicker frequency determiner 54 may determine the flicker frequency from the differential image data acquired by the differential image data acquirer 52 through various methods, for example, using a Fourier transform. The Fourier transform is a function of time or coordinates that is transformed into a function of frequency to find the flicker frequency.

In the case of the digital photographing apparatus according to the present embodiment, even if a user moves several regions, there is no need to investigate frequencies causing flicker in each region. For example, in Korea and Europe, 60Hz power is used as AC power, so the flicker frequency is 120Hz. In Japan, the flicker frequency is 100Hz or 120Hz depending on the region. With the device, you can automatically determine the flicker frequency in your area, and display clean, high quality live video images without flicker on the display, or store data on clean high quality live video images without flicker on the storage media. .

3 is a conceptual diagram schematically showing an image pickup device 30 which is a part of FIG. The imaging device 30 has a structure in which a plurality of optical recognition devices are arranged in a two-dimensional array. In FIG. 3, nine optical recognition elements are arranged horizontally and eight vertically, but this is merely an example and the present invention is not limited thereto. As described above, the image pickup device 30 has a plurality of optical recognition devices. As described above, obtaining the differential image data in the two frames and determining the flicker frequency from all the optical recognition devices of the image pickup device 30 are as follows. It may also be done using data from the elements. However, determining the flicker frequency by using data from all optical recognition elements of the imaging device 30 due to the high resolution of the digital photographing apparatus, etc., requires a large amount of time to determine the flicker frequency. It may also be excessive power consumption.

Therefore, the digital photographing apparatus according to the present embodiment may not use all the optical recognition elements of the image pickup device 30 in the process of determining the flicker frequency. That is, the data for two frame images are acquired in the plurality of sampling areas A1, A2, A3, A4, and A5 of the imaging device 30, and the difference image data acquisition unit 52 is configured to acquire the imaging device 30. Differential image data may be obtained in each sampling area of the? Thereafter, the flicker frequency determiner 54 determines flicker frequencies from the differential image data acquired by the differential image data acquisition unit 52 in each sampling area of the imaging device 30, and digitally determines the flicker frequencies from the plurality of flicker frequencies. The flicker frequency may be determined by an environment in which the photographing apparatus is used. This reduces the amount of computation required to determine flicker frequency, resulting in faster flicker frequency determination.

Of course, one partial sampling area of the image pickup device 30 may be selected, but in this case, the flicker frequency may not be accurately determined. That is, light of a different intensity may be incident on all regions of the image pickup device 30 evenly, but light of different intensities may be incident on the region of the image pickup device 30. It is preferable to prevent the occurrence of an error due to such a difference in incident light by selecting two sampling regions. In this case, it is preferable that the plurality of sampling regions exist in various regions of the image pickup device 30.

For example, in the case of the image pickup device 30 as shown in FIG. 3, five sampling regions A1, A2, A3, A4, and A5 are shown to exist. In this case, data for two frame images is obtained in each sampling area. The differential image data acquisition unit 52 obtains differential image data in sampling areas of A1, A2, A3, A4, and A5, respectively. The flicker frequency determination unit 54 first determines the flicker frequency in each sampling area of A1, A2, A3, A4 and A5. Since there is differential image data in each of the sampling regions A1, A2, A3, A4 and A5 and they may be different from each other, the flicker frequency determiner 54 has a plurality of flicker frequencies. Then, the flicker frequency determiner 54 determines which frequency is the final flicker frequency from the plurality of flicker frequencies. For example, the largest flicker frequency may be used as the final flicker frequency. In addition, since the flicker frequencies are obtained in the plurality of sampling regions A1, A2, A3, A4, and A5, the most frequent flicker frequency may be determined as the final flicker frequency.

Meanwhile, as shown in FIG. 3, a plurality of optical recognition elements are disposed in each sampling area. Therefore, in order to easily find one flicker frequency in each sampling region, the following process may be performed.

First, the difference image data unit 52 may, in each column of each sampling area of the imaging device 30, obtain a first value which is a sum, average, or processed value of data from pixels belonging to each column in each frame image. The difference image data, which is the difference between the first values corresponding to the two frame images, can be obtained in each sampling area of the image pickup device 30. For example, in the sampling area of A1 for the first frame image, a first value which is the sum, average, or processed value of data from the light recognition elements 311 and 321 belonging to the same column is obtained. The first value is obtained from the photorecognition elements 312 and 322 belonging to the second column of the sampling area of A1, and from the photorecognition elements 313 and 323 belonging to the third column of the sampling area of A1. Get 1 value. As a result, a first value corresponding to the number of columns in the sampling area of A1 is obtained for the first frame image. In each sampling area of A2, A3, A4 and A5, a first value corresponding to the number of columns is obtained. For the second frame image, a first value corresponding to the number of columns is obtained in each sampling area of A1, A2, A3, A4, and A5.

Then, the differential image data is obtained from the first value in the first column for the first frame image and the first value in the first column for the second frame image in the sampling area of A1. And in the sampling area of A1, obtain differential image data from the first value in the second column for the first frame image and the first value in the second column for the second frame image, and finally in the sampling area of A1. Difference image data is obtained from a first value in a third column for a first frame image and a first value in a third column for a second frame image. As a result, differential image data corresponding to the number of columns in the sampling area of A1 is obtained. Differential image data corresponding to the number of columns is also obtained in each sampling area of A2, A3, A4 and A5.

Next, the flicker frequency determination unit 54 determines the flicker frequency in the corresponding column from the differential image data in each column in the sampling area of A1. That is, the flicker frequency determiner 54 determines flicker frequencies corresponding to the number of columns in the sampling area of A1. In the case of FIG. 3, three flicker frequencies are obtained in the sampling region of A1. Of course, two of them may coincide to obtain two flicker frequencies, or all three may coincide to obtain one flicker frequency. have. If a plurality of flicker frequencies are obtained without obtaining one flicker frequency in the sampling region of A1, the maximum flicker frequency is determined as the flicker frequency in the sampling region of A1. As described above, the flicker frequency determiner 54 first determines the flicker frequency in each sampling area. From the flicker frequencies in the plurality of sampling areas, the flicker frequency (final flicker frequency) according to the environment in which the digital photographing apparatus is used is determined. For example, the largest flicker frequency may be used as the final flicker frequency. In addition, since the flicker frequencies are obtained in the plurality of sampling regions A1, A2, A3, A4, and A5, the most frequent flicker frequency may be determined as the final flicker frequency.

4 is a flowchart schematically illustrating a process of determining a flicker frequency according to an environment in which a digital photographing apparatus having an image pickup device according to another embodiment of the present invention is used.

As shown in FIG. 4, data for two frame images is obtained in a plurality of sampling regions of the image pickup device (S10). Here, the two frame images may be continuous frame images. Thereafter, in each sampling area of the image pickup device, difference image data for a difference image that is a difference between two frame images is obtained (S20). Next, in each sampling area of the imaging device, the flicker frequency is determined from the differential image data (S30), and from the flicker frequencies obtained in the plurality of sampling areas of the imaging device, the flicker frequency of the environment in which the digital photographing apparatus is used. Determine (S40).

When acquiring the differential image data (S20), a first value which is a sum, average, or processed value of data from pixels belonging to each column in each frame image in each column of each sampling area of the image pickup device is obtained, and A process may be performed to obtain differential image data of a difference image, which is a difference between first values corresponding to two frame images in each sampling area. In this case, when determining the flicker frequency in each sampling area of the imaging device (S30), the flicker frequency in each column is determined from the differential image data in each sampling area of the imaging device, and then each column in each sampling area of the imaging device. The maximum value of the flicker frequencies in may be determined as the flicker frequency in the corresponding sampling region.

The program for executing the flicker frequency determination method according to the above-described embodiments and variations thereof in the digital photographing apparatus may be stored in a recording medium. Here, the recording medium may be a storage medium 80 as shown in FIG. 1, a memory 60 as shown in FIG. 1, or another separate recording medium. The recording medium may be a storage medium such as a magnetic storage medium (for example, a ROM, a floppy disk, a hard disk, etc.) and an optical reading medium (for example, a CD-ROM, a DVD (Digital Versatile Disc)). Include. Of course, for example, it may be the CPU 100 in FIG. 1 or a part thereof.

Although the present invention has been described with reference to the embodiments shown in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a block diagram schematically showing a digital photographing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram schematically illustrating a portion of FIG. 1.

3 is a conceptual diagram schematically illustrating an image pickup device that is a part of FIG. 1.

4 is a flowchart schematically illustrating a process of determining a flicker frequency according to an environment in which a digital photographing apparatus having an image pickup device according to another embodiment of the present invention is used.

<Explanation of symbols for the main parts of the drawings>

10: lens 11: lens driving unit

20: aperture 21: aperture driving unit

30: imaging device 31: imaging device controller

40: A / D conversion unit 50: digital signal processing unit

60: memory 71: storage / reading control

70: storage medium 81: display control unit

80: display unit 100: CPU

200: control panel

Claims (9)

As a method of determining the flicker frequency due to the environment in which a digital photographing apparatus having an image pickup device is used, (a) acquiring data for two frame images in a plurality of sampling regions of the imaging device; (b) acquiring difference image data for a difference image which is a difference between the two frame images in each sampling area of the image pickup device; (c) in each sampling area of the imaging device, determining a flicker frequency from said differential image data; And (d) determining flicker frequencies from the flicker frequencies obtained in the plurality of sampling regions of the image pickup device according to the environment in which the digital photographing apparatus is used. The method of claim 1, And the two frame images in step (a) are successive frame images. The method of claim 1, In step (b), (b1) obtaining a first value in each column of each sampling area of the imaging device, which is a sum, average, or processed value of data from pixels belonging to each column in each frame image; And (b2) obtaining, in each sampling area of the image pickup device, difference image data for a difference image which is a difference of a first value corresponding to each other in the two frame images. The method of claim 3, In step (c), (c1) in each sampling area of the imaging device, determining the flicker frequency in each column from the differential image data; And (c2) in each sampling area of the imaging device, determining a maximum value of the flicker frequencies in each column as the flicker frequency in the corresponding sampling area. A recording medium storing a program for executing the method of any one of claims 1 to 4. An imaging device for generating image data from incident light; A differential image data acquisition unit for obtaining differential image data for a differential image that is a difference between two frame images obtained from the image pickup device; And And a flicker frequency determiner configured to determine a flicker frequency from the differential image data obtained by the differential image data acquisition unit. The method of claim 6, The image pickup device acquires data for two frame images in a plurality of sampling regions, The differential image data acquisition unit obtains differential image data in each sampling area of the imaging device, The flicker frequency determiner determines flicker frequencies from differential image data obtained by the differential image data acquisition unit in each sampling area of the image pickup device, and determines flicker frequencies from an environment in which a digital photographing apparatus is used from a plurality of flicker frequencies. Digital shooting apparatus, characterized in that for determining. The method of claim 7, wherein The difference image data acquisition unit, In each column of each sampling area of the image pickup device, a first value is obtained, which is a sum, average, or processed value of data from pixels belonging to each column in each frame image, And in each sampling area of the image pickup device, difference image data which is a difference between mutually corresponding first values in two frame images. The method of claim 8, The flicker frequency determiner, In each sampling area of the imaging device, the flicker frequency in each column is determined from the differential image data obtained by the differential image data acquisition unit, In each sampling area of the imaging device, the maximum value of the flicker frequencies in each column is determined as the flicker frequency in the corresponding sampling area, And a flicker frequency determined by an environment in which the digital photographing apparatus is used from the plurality of flicker frequencies.

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