CN113079322B - Imaging system and flicker elimination method thereof - Google Patents
Imaging system and flicker elimination method thereof Download PDFInfo
- Publication number
- CN113079322B CN113079322B CN202110336287.5A CN202110336287A CN113079322B CN 113079322 B CN113079322 B CN 113079322B CN 202110336287 A CN202110336287 A CN 202110336287A CN 113079322 B CN113079322 B CN 113079322B
- Authority
- CN
- China
- Prior art keywords
- image
- imaging system
- brightness
- flicker
- light source
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000003384 imaging method Methods 0.000 title claims abstract description 95
- 238000000034 method Methods 0.000 title claims abstract description 25
- 230000008030 elimination Effects 0.000 title claims abstract description 13
- 238000003379 elimination reaction Methods 0.000 title claims abstract description 13
- 238000005286 illumination Methods 0.000 claims abstract description 93
- 238000009432 framing Methods 0.000 claims abstract description 20
- 238000012545 processing Methods 0.000 claims description 17
- 238000001514 detection method Methods 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 4
- 238000002310 reflectometry Methods 0.000 claims description 4
- 230000000737 periodic effect Effects 0.000 description 11
- 238000010586 diagram Methods 0.000 description 7
- 230000008859 change Effects 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 230000004397 blinking Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/745—Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/73—Circuitry for compensating brightness variation in the scene by influencing the exposure time
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Studio Devices (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
Abstract
The invention provides an imaging system and a flicker elimination method of the imaging system. Acquiring an image signal shot by an image sensor under an illumination light source; acquiring the framing period and the exposure time of a current imaging system; calculating the angular frequency of the illumination light source according to the image signal and the phase of the current imaging system relative to the illumination light source; and calculating a compensation signal required for eliminating the flicker of the image, and performing row-by-row compensation on the original data before entering the image processor so as to eliminate the flicker. The brightness of the compensated image is proportional to the exposure time, and the brightness of the whole image is uniform. According to the invention, flicker is eliminated through the compensation signal, and the exposure time does not need to be modified to adapt to the frequency of the illumination light source, so that the flicker can be removed under the condition of ensuring the brightness of the image, and the image with uniform brightness can be obtained in the image with high dynamic range. Furthermore, the invention can ensure the frame rate required by the imaging system without modifying the framing period or the frame rate to adapt to the frequency of the illumination source.
Description
Technical Field
The invention belongs to the field of image sensors, and particularly relates to an imaging system and a flicker elimination method of the imaging system.
Background
With the popularization of vehicle-mounted monitoring camera systems in practical applications, image sensors (such as high dynamic range CMOS image sensors) are increasingly applied to these systems, and accurate image content and high frame rate are required.
The image sensor converts an optical signal into an electrical signal, and the light source of the optical signal is a natural light source (e.g., the sun) and/or an illumination light source (such as an electric bulb, a fluorescent lamp, and a mercury lamp). In practical applications, most illumination light sources are periodic signals which change with time, and in general, in Alternating Current (AC) power supply, brightness of the light source changes at a frequency 2 times of the AC power supply frequency to generate light and dark alternation, so that the problem of flicker caused by mismatch between exposure time and the power supply frequency of the illumination light source (artificial light source) exists.
The flicker problem includes image brightness flicker (moire) within an imaging system frame and image brightness flicker from imaging system frame to frame. This flicker problem is particularly severe in short exposure as well as very short exposure, and needs to be addressed.
In the existing method, the frequency of an illumination light source is detected, the exposure time is modified to adapt to the frequency of the illumination light source, so that flicker is eliminated, and the brightness of a shooting target cannot be ensured by eliminating the flicker.
The method can not ensure the required frame rate and has uneven brightness in space.
Disclosure of Invention
The invention aims to provide an imaging system and a flicker elimination method of the imaging system, which are used for compensating original data before entering an image processor so as to eliminate flicker.
The invention provides a flicker elimination method of an imaging system, which comprises the following steps:
acquiring an image signal shot by an image sensor under an illumination light source;
acquiring the framing period and the exposure time of a current imaging system;
calculating the angular frequency of an illumination light source and the current phase of the imaging system relative to the illumination light source according to the image signal;
calculating an image brightness as a function of the exposure time, the angular frequency of the illumination source, and the phase of the imaging system relative to the illumination source;
and calculating a compensation signal, wherein the product of the image brightness and the compensation signal is the compensated image brightness, the compensated image brightness is in direct proportion to the exposure time through compensation, and the brightness of the whole image is uniform.
Further, a method for calculating the angular frequency of the illumination source and the current phase of the imaging system relative to the illumination source includes:
the image signal is an A multiplied by B pixel array, the pixel array is divided into a plurality of blocks, a statistical module samples in each block to obtain average brightness of each block, and the angular frequency of the illumination light source and the current phase of the imaging system relative to the illumination light source are calculated according to the average brightness.
Further, the central processing unit or the microprocessor runs an executable program or an application program to detect the angular frequency of the illumination light source and detect the phase according to the average brightness, so as to obtain the angular frequency of the illumination light source and the current phase of the imaging system relative to the illumination light source.
Further, the statistics module is configured in the image sensor or in an image processor.
Further, a flicker compensation module is configured in the image processor, and the flicker compensation module calculates the compensation signal.
Further, the compensation signal is an inverse function of the image brightness.
Further, the image brightness Lum expression of the i-th frame image is:
wherein, epeak is the energy peak value of alternating current, and ζ is the reflectivity of the object irradiated by the illumination light source; ω is referred to as the angular frequency of the illumination source,
the expo is the exposure time for the current phase of the imaging system relative to the illumination source.
Further, the expression of the compensation signal Gain is:
compensated image brightness Lum result The expression of (2) is:
Lum result =lum x Gain, α takes a constant, let Lum result The expression of (C) contains the following
The term of (2) is equal to 0, so that the Lum result And calculating a compensation coefficient beta in proportion to the exposure time expo, so as to obtain the compensation signal Gain.
The present invention also provides an imaging system comprising:
the image processing device comprises an image sensor, a central processing unit or a microprocessor and an image processor, wherein a flicker compensation module is configured in the image processor;
the image sensor is used for shooting an image signal of a shot object under an illumination light source;
the central processing unit or the microprocessor calculates the angular frequency of the illumination light source and the current phase of the imaging system relative to the illumination light source according to the image signal, and transmits the angular frequency and the current phase of the imaging system relative to the illumination light source to the flicker compensation module;
the image processor is communicated with the image sensor to acquire the framing period and the exposure time of the current imaging system;
the flicker compensation module applies a compensation signal to obtain compensated image brightness.
Further, the imaging system also includes a statistics module configured in the image sensor or the image processor.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides an imaging system and a flicker elimination method of the imaging system. Acquiring an image signal shot by an image sensor under an illumination light source; acquiring the framing period and the exposure time of a current imaging system; calculating the angular frequency of an illumination light source and the current phase of the imaging system relative to the illumination light source according to the image signal; and calculating a compensation signal required for eliminating the flicker of the image, and performing row-by-row compensation on the original data before entering the image processor so as to eliminate the flicker. The brightness of the compensated image is proportional to the exposure time, and the brightness of the whole image is uniform. The invention eliminates flicker through the compensation signal, and can keep the original exposure time, framing period and frame rate of the imaging system; the exposure time does not need to be modified to adapt the frequency of the illumination source, so flicker can be removed while ensuring the brightness of the image, and an image of uniform brightness can be obtained in a high dynamic range image (HDR). Furthermore, the invention can ensure the frame rate required by imaging without modifying the framing period or the frame rate to adapt to the frequency of the illumination light source.
Drawings
Fig. 1 is a schematic diagram of an image showing flickering.
Fig. 2 is a schematic diagram explaining the principle of the flicker phenomenon in the image forming apparatus.
Fig. 3 is a graph of image brightness when the exposure time is not an integer multiple of the blinking period of the fluorescent lamp.
Fig. 4 is a flowchart of a flicker removing method of an imaging system according to an embodiment of the invention.
Fig. 5 is a schematic diagram of an imaging system statistics module configured in an image sensor according to an embodiment of the present invention.
Fig. 6 is a schematic diagram of an imaging system statistics module configured in an image processor according to an embodiment of the present invention.
Detailed Description
As described in the background, flicker problems of the imaging system are prone to occur due to the mismatch of the exposure time and the frequency of the illumination source.
Specifically, a CMOS type image sensor having low power consumption is an imaging device in which pixels are provided by a matrix; the incident light is converted into an electronic signal by an imaging device; charge (image signal) is accumulated on one pixel; the charge is read out by designating the X-Y address of the pixel. An imaging device, such as a CMOS type image sensor or the like, is called an X-Y addressed scanning type solid-state imaging device.
When an object is imaged with an X-Y addressed scanning type solid-state imaging device, such as a CMOS type image sensor, under illumination with a common fluorescent lamp using an Alternating Current (AC) power supply, since the fluorescent lamp blinks in synchronization with the frequency of the AC power supply, the scanning time point varies depending on the position of the pixel. As a result, bright areas and dark areas are generated in an image, degrading the quality of the image. Fig. 1 is a schematic diagram of an image showing flickering. As shown in fig. 1, a stripe pattern appears in one frame of the apple image, in which dark portions and bright portions extending in the horizontal direction appear alternately, that is, flickering occurs.
Fig. 2 is a diagram for explaining the principle of the flicker phenomenon occurring in an X-Y addressing scanning type solid-state imaging device. As shown in fig. 2, for example, the frequency of an ac power supply is 50Hz, the flicker frequency of a fluorescent lamp is 100Hz (i.e., the flicker period is 10 ms), and the flicker frequency of a fluorescent lamp is typically 2 times the frequency of the ac power supply. The framing frequency of the imaging device is 30fps (i.e., the framing period is 33.3 ms). In this case, the vertical scanning time (framing period) is 33.3 milliseconds, during which all pixels are read from top to bottom (left to right) in the vertical direction. During the vertical scan time, the fluorescent lamp blinks in synchronization with the frequency of the AC power supply. Therefore, when one pixel in the (n-1) -th row, one pixel in the n-th row, and the pixel in the (n+1) -th row are read, the respective light intensities (luminance values of fluorescent lamps) entered on the image forming apparatus are different from each other. The image sensor converts an optical signal into an electrical signal, and thus, a stripe-like pattern that can be observed appears on one frame of an image, in which bright portions and dark portions extending in the horizontal direction alternately appear, and both flickering occurs, resulting in a decrease in the quality of the obtained pattern. Fig. 3 is a graph of image brightness when the exposure time is not an integer multiple of the blinking period of the fluorescent lamp. As shown in fig. 3, when the exposure time (vertical scanning time) expo is not an integer multiple of one flicker period of the fluorescent lamp, for example, expo+.n×10ms (n∈z), the change of the ordinate image luminance with the exposure time expo becomes a waveform curve.
Based on the above-mentioned researches, the embodiment of the invention provides a flicker elimination method of an imaging system. The invention is described in further detail below with reference to the drawings and the specific examples. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are not to scale precisely, but rather merely for the purpose of facilitating and clearly aiding in the description of the embodiments of the invention.
An embodiment of the present invention provides a method for eliminating flicker of an imaging system, as shown in fig. 4, including:
step S1, acquiring an image signal shot by an image sensor under an illumination light source;
s2, acquiring the framing period and the exposure time of a current imaging system;
s3, calculating the angular frequency of an illumination light source and the current phase of the imaging system relative to the illumination light source according to the image signal;
step S4, calculating image brightness, wherein the image brightness is a function of the exposure time, the angular frequency of the illumination light source and the phase of the imaging system relative to the illumination light source;
and S5, calculating a compensation signal, wherein the product of the image brightness and the compensation signal is the compensated image brightness, and the compensated image brightness is in direct proportion to the exposure time through compensation, and the brightness of the whole image is uniform.
Specifically, fig. 5 and 6 are two schematic diagrams of an imaging system according to an embodiment of the present invention. The imaging system includes: an image sensor, a central processor/microprocessor, an image processor (ISP, image Signal Processor). The imaging system further includes: a statistics module and a flicker compensation module. The flicker compensation module is configured in the image processor. The statistics module is configured in the image sensor or in an image processor. FIG. 5 shows a statistics module T 1 Is configured in the image sensor; FIG. 6 shows a statistics module T 2 Is configured in the image processor.
Step S1, acquiring an image signal shot by an image sensor under an illumination light source. The image sensor is an element that has a plurality of pixels arranged in a two-dimensional manner, which converts light into an electrical signal, and images an object with the plurality of pixels. The pixel includes a photoelectric conversion element formed using a photodiode or an organic photoelectric conversion film. The image sensor is provided as a MOS (metal oxide semiconductor) imaging element capable of designating a readout signal from an arbitrary pixel by an XY address; CCD (charge coupled device) type imaging elements may also be used. In some countries or regions, the frequency of the alternating current power supply of the illumination light source is 50Hz; whereas in some countries or regions the frequency of the ac power supply of the illumination source is 60Hz.
Step S2, a framing period VTS and an exposure time expo of the current imaging system are obtained.
Step S3, calculating the angular frequency omega of the illumination light source and the current phase of the imaging system relative to the illumination light source according to the image signal
Comprises the following steps:
the image signal is a pixel array of a×b (for example 3840×2160), and to improve the efficiency of image processing, the pixel array is divided into a plurality of blocks, and the pixel array of a×b may be divided into m×n (for example 16×16) blocks (blocks), where each block includes: (A/M) x (B/N) (e.g., 240X 135). The statistics module is used for sampling in each block, the statistics module obtains the average brightness of each block according to a certain principle, and the central processing unit or the microprocessor runs corresponding execution programs according to the average brightness to perform the angular frequency detection and the phase detection of the illumination light source. The execution program can calculate and obtain the angular frequency omega of the illumination light source and the phase of the imaging system relative to the illumination light source by adopting a Fourier transform (FFT) algorithm or a front-back frame difference algorithm
Step S4, calculating an image brightness Lum, wherein the image brightness Lum is related to the exposure time expo, the angular frequency omega of the illumination light source and the phase of the imaging system relative to the illumination light source
Is a function of (2).
Step S5, calculating a compensation signal Gain by the flicker compensation module, wherein the product of the image brightness (periodical brightness change of the image) Lum and the compensation signal Gain is the compensated image brightness Lum result I.e. Lum result =lum×gain, compensated image brightness Lum result As a non-periodic function. The brightness of the compensated image is in direct proportion to the exposure time through compensation, and the brightness of the whole image is uniform.
Since the image brightness Lum is illuminationAngular frequency ω of light source, imaging system exposure time expo, and phase information of imaging system relative to illumination light source
Since the compensation signal Gain is an inverse function of the image brightness Lum, the compensation signal Gain is also a function of the above variables, denoted as Gain (ω, expo, ">
). The framing period VTS of the imaging system directly affects the frame-to-frame phase variation. The image luminance Lum is a periodic signal, the compensation signal Gain is also a periodic signal, and the image luminance Lum after compensation is compensated result The brightness of the whole image is uniform and flicker is eliminated by compensation for non-periodic signals, namely periodic signals with alternate brightness and darkness. The present patent uses periodic compensation signals to eliminate flicker due to the mismatch between exposure time and illumination source period.
Raw Data (Raw Data) output by the image sensor is sent to an image processor, and a flicker compensation module is configured in the image processor; the image processor communicates with the image sensor to acquire the framing period VTS and the exposure time expo of the current imaging system. The flicker compensation module communicates with a central processor or microprocessor to obtain the frequency ω of the illumination source and the phase phi of the imaging system relative to the illumination source.
Statistics module T in FIG. 5 1 Arranged in the image sensor, a statistics module T 1 According to the image signal shot by the image sensor, carrying out block statistics, transmitting the average brightness information to a central processing unit or a microprocessor, and carrying out angular frequency detection and phase detection of the illumination light source by the central processing unit or the microprocessor to obtain the angular frequency omega of the illumination light source and the current phase of the imaging system relative to the illumination light source
And transmitted to the flicker compensation module, which calculates a compensation signal.
Statistics module T in FIG. 6 2 Arranged in the image processor, a statistics module T 2 According to the image signal shot by the image sensor, carrying out block statistics, transmitting the average brightness information to a central processing unit or a microprocessor, and carrying out angular frequency detection and phase detection of the illumination light source by the central processing unit or the microprocessor to obtain the angular frequency omega of the illumination light source and the current phase of the imaging system relative to the illumination light source
And transmitted to the flicker compensation module, which calculates a compensation signal.
The magnitude of the output signal of the image sensor is proportional to the output power of the light source in addition to the photoelectric conversion efficiency itself. The function calculation formula of the output power p of the alternating current power supply with respect to time x is as follows:
wherein, vpak is the alternating current peak voltage, R is the equivalent resistance of the illumination light source,
epeak is the energy peak value of alternating current, and ζ is the reflectivity of the object irradiated by the illumination light source; ω is called angular frequency, which is also a physical quantity reflecting how fast the alternating current changes with time. The relationship between the angular frequency and the frequency is ω=2pi f, and ω=100deg.pi when the frequency f of the alternating current is 50Hz; when the frequency f of the alternating current is 60Hz, ω=120pi.
The compensation signal Gain is an inverse function of the image luminance (the periodical light and shade variation of the image) Lum, and the flicker component is eliminated by multiplying the compensation signal Gain by the image luminance Lum.
Based on the four acquired key parameters VTS, expo, ω and
and the energy output of the alternating current can be used for obtaining the integral expression of the brightness (full-image brightness change) of the ith frame image,
frame i, a certain phase
The brightness of the image after the position is exposed with the time with the value of expo is
The phase of a line of the image is related to the absolute position where the line is located. Assuming the phase of line 0 data is
The phase position of the nth row is +.>
From the above formula, it can be derived that the brightness of a certain line is along with the phase +.>
Changes occur as a periodic function of the brightness of the image ω. Then a frame of image is composed of a row of data, which is reflected in a periodic change in brightness from top to bottom.
To eliminate this flicker, a periodically compensated Gain is used
∵α＝1,
∴
α takes a constant (fixed value), and an exemplary α takes 1. Letting said Lum result The expression of (C) contains the following
The term of (2) is equal to 0, so that the Lum result And calculating a compensation coefficient beta in proportion to the exposure time expo, so as to obtain the compensation signal Gain.
The brightness of any row in the i-th frame after compensation is as follows:
the brightness of the image of each line in the i-th frame is independent of the phase, and satisfies the above expression. So that the brightness of the image of each frame is uniform and proportional to the exposure time expo.
Introducing the imaging system period VTS into the following frame compensation data calculation, namely obtaining:
step S51, obtaining phase information of a certain frame
After that, if VTS, expo, ω is unchanged, the phase information of each line of each frame can be deduced thereafter +.>
And thus a compensating periodic function is obtained and applied to each line of data.
Steps S52, VTS, expo, ω,
any one of which is changed, the compensation periodic function is recalculated.
The present embodiment also provides an imaging system including:
the image processing device comprises an image sensor, a central processing unit or a microprocessor and an image processor, wherein a flicker compensation module is configured in the image processor;
the image sensor is used for shooting an image signal of a shot object under an illumination light source;
the central processing unit or the microprocessor calculates the angular frequency of the illumination light source and the current phase of the imaging system relative to the illumination light source according to the image signal, and transmits the angular frequency and the current phase of the imaging system relative to the illumination light source to the flicker compensation module;
the image processor is communicated with the image sensor to acquire the framing period and the exposure time of the current imaging system;
the flicker compensation module calculates a compensation signal to obtain compensated image brightness.
The imaging system further includes a statistics module configured in the image sensor or the image processor. The image processor processes the compensated image brightness signal.
In summary, the present invention provides an imaging system and a flicker eliminating method for the imaging system. Acquiring an image signal shot by an image sensor under an illumination light source; acquiring the framing period and the exposure time of a current imaging system; calculating the angular frequency of an illumination light source and the current phase of the imaging system relative to the illumination light source according to the image signal; and calculating a compensation signal required for eliminating the flicker of the image, and performing row-by-row compensation on the original data before entering the image processor so as to eliminate the flicker. The brightness of the compensated image is proportional to the exposure time, and the brightness of the whole image is uniform. The invention eliminates flicker through the compensation signal, and can keep the original exposure time, framing period and frame rate of the imaging system; the exposure time does not need to be modified to adapt the frequency of the illumination source, so flicker can be removed while ensuring the brightness of the image, and an image of uniform brightness can be obtained in a high dynamic range image (HDR). Furthermore, the invention can ensure the frame rate required by imaging without modifying the framing period or the frame rate to adapt to the frequency of the illumination light source.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the method disclosed in the embodiment, the description is relatively simple since it corresponds to the device disclosed in the embodiment, and the relevant points refer to the description of the method section.
The above description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any alterations and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.
Claims (9)
1. A method of flicker cancellation in an imaging system, comprising:
acquiring an image signal shot by an image sensor under an illumination light source;
acquiring the framing period and the exposure time of a current imaging system;
calculating the angular frequency of the illumination light source and the current phase of the imaging system relative to the illumination light source according to the image signal;
calculating an image brightness as a function of the exposure time, the angular frequency of the illumination source, and the phase of the imaging system relative to the illumination source;
calculating a compensation signal, wherein the product of the image brightness and the compensation signal is the compensated image brightness, the calculation is performed by making a term related to the phase in an expression of the compensated image brightness equal to 0, the compensated image brightness is in direct proportion to the exposure time through compensation, and the brightness of the whole image is uniform;
wherein, the image brightness Lum expression of the ith frame image is:
wherein, epeak is the energy peak value of alternating current, and ζ is the reflectivity of the object irradiated by the illumination light source; ω is referred to as the angular frequency of the illumination source,
the expo is the exposure time for the current phase of the imaging system relative to the illumination source.
2. The imaging system flicker elimination method of claim 1, wherein the method of calculating the angular frequency of the illumination source and the current phase of the imaging system relative to the illumination source comprises:
the image signal is an A multiplied by B pixel array, the pixel array is divided into a plurality of blocks, a statistical module samples in each block to obtain average brightness of each block, and the angular frequency of the illumination light source and the current phase of the imaging system relative to the illumination light source are calculated according to the average brightness.
3. The imaging system flicker elimination method of claim 2, wherein a central processor or microprocessor runs an executable program or application program for said illumination source angular frequency detection and said phase detection based on said average brightness to obtain an angular frequency of said illumination source and a current phase of said imaging system relative to said illumination source.
4. The imaging system flicker elimination method of claim 2, wherein said statistics module is configured in said image sensor or in an image processor.
5. The imaging system flicker elimination method of claim 4, wherein a flicker compensation module is configured in said image processor, said flicker compensation module calculating said compensation signal.
6. The imaging system flicker cancellation method of claim 1, wherein the compensation signal is an inverse function of the image brightness.
7. The imaging system flicker elimination method of claim 1, wherein,
the expression of the compensation signal Gain is:
compensated image brightness Lum result The expression of (2) is:
Lum result =lum x Gain, α takes a constant, let Lum result The expression of (C) contains the following
The term of (2) is equal to 0, so that the Lum result And calculating a compensation coefficient beta in proportion to the exposure time expo, so as to obtain the compensation signal Gain.
8. An imaging system, comprising:
the image processing device comprises an image sensor, a central processing unit or a microprocessor and an image processor, wherein a flicker compensation module is configured in the image processor;
the image sensor is used for shooting an image signal of a shot object under an illumination light source;
the central processing unit or the microprocessor calculates the angular frequency of the illumination light source and the current phase of the imaging system relative to the illumination light source according to the image signal, and transmits the angular frequency and the current phase to the flicker compensation module;
the image processor is communicated with the image sensor to acquire the framing period and the exposure time of the current imaging system;
the flicker compensation module calculates a compensation signal to obtain compensated image brightness; the product of the image brightness and the compensation signal is the compensated image brightness, the calculation is performed by making the term related to the phase in the expression of the compensated image brightness equal to 0, the compensated image brightness is in direct proportion to the exposure time through compensation, and the brightness of the whole image is uniform;
wherein, the image brightness Lum expression of the ith frame image is:
wherein, epeak is the energy peak value of alternating current, and ζ is the reflectivity of the object irradiated by the illumination light source; ω is referred to as the angular frequency of the illumination source,
and the exposure time is the current phase of the imaging system relative to the illumination light source.
9. The imaging system of claim 8, further comprising a statistics module configured in the image sensor or the image processor; and the statistical module is used for carrying out block statistics according to the image signals shot by the image sensor and transmitting the average brightness information of statistics to the central processing unit or the microprocessor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110336287.5A CN113079322B (en) | 2021-03-29 | 2021-03-29 | Imaging system and flicker elimination method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110336287.5A CN113079322B (en) | 2021-03-29 | 2021-03-29 | Imaging system and flicker elimination method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113079322A CN113079322A (en) | 2021-07-06 |
| CN113079322B true CN113079322B (en) | 2023-04-28 |
Family
ID=76611284
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110336287.5A Active CN113079322B (en) | 2021-03-29 | 2021-03-29 | Imaging system and flicker elimination method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113079322B (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104104882A (en) * | 2013-04-09 | 2014-10-15 | 展讯通信（上海）有限公司 | Image flicker detection method and device, and image capturing device |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4904749B2 (en) * | 2005-09-08 | 2012-03-28 | ソニー株式会社 | Flicker reduction method, flicker reduction circuit, and imaging apparatus |
| KR20080098864A (en) * | 2007-05-07 | 2008-11-12 | 삼성전자주식회사 | Method and apparatus for reducing flicker noise in image sensor |
| JP2009077057A (en) * | 2007-09-19 | 2009-04-09 | Olympus Imaging Corp | Imaging apparatus, and control method for imaging apparatus |
| JP2011030093A (en) * | 2009-07-28 | 2011-02-10 | Sanyo Electric Co Ltd | Video camera |
| JP5625371B2 (en) * | 2010-01-29 | 2014-11-19 | ソニー株式会社 | Image processing apparatus, signal processing method, and program |
| US20110292241A1 (en) * | 2010-05-30 | 2011-12-01 | Logitech Europe S.A. | Extended flicker cancellation for auto exposure for a video camera |
| JP5296112B2 (en) * | 2011-02-04 | 2013-09-25 | パナソニック株式会社 | Flicker correction apparatus, flicker correction method, and flicker correction program |
| JP5936478B2 (en) * | 2012-08-03 | 2016-06-22 | キヤノン株式会社 | Measuring apparatus, lithography apparatus, and article manufacturing method |
| CN105120133B (en) * | 2015-09-14 | 2018-05-25 | 浙江大华技术股份有限公司 | A kind of elimination image flicker phenomenon method and device |
-
2021
- 2021-03-29 CN CN202110336287.5A patent/CN113079322B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104104882A (en) * | 2013-04-09 | 2014-10-15 | 展讯通信（上海）有限公司 | Image flicker detection method and device, and image capturing device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113079322A (en) | 2021-07-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7764312B2 (en) | Flicker correction method and device, and imaging device | |
| EP1455523B1 (en) | Scanning device calibration system and method | |
| US6501518B2 (en) | Method and apparatus for reducing flicker effects from discharge lamps during pipelined digital video capture | |
| EP1253780B1 (en) | Method of reducing flicker noises of X-Y address type solid-state image pickup device | |
| KR100515225B1 (en) | Flicker correction apparatus and flicker correction method, and recording medium storing flicker correction program | |
| US7639285B2 (en) | Flicker reduction method, flicker reduction circuit and image pickup apparatus | |
| CN1226866C (en) | Solid-state image sensor | |
| US9232153B2 (en) | Flicker compensation method using two frames | |
| CN101472059A (en) | Image processing apparatus and image processing method | |
| GB2568924A (en) | Method of flicker reduction | |
| US10591711B2 (en) | Microscope and method for obtaining a high dynamic range synthesized image of an object | |
| CN1604619A (en) | Black level correction circuit and method for imaging apparatus using solid imaging element | |
| CN111602386A (en) | LED stroboscopic mitigation for motion pictures | |
| CN109525840A (en) | The detection method of minor defect on a kind of imager chip | |
| CN113079322B (en) | Imaging system and flicker elimination method thereof | |
| US20130070088A1 (en) | Method for measuring electronic multiplication factor | |
| Kontaxis et al. | Applications of CCD sensors in photometry and in daylight responsive systems | |
| JP2003179949A (en) | Luminance level inspecting apparatus | |
| US20190281193A1 (en) | Method and system to calibrate a camera clock using flicker | |
| JP5818451B2 (en) | Imaging apparatus and control method | |
| JP4515991B2 (en) | Flicker noise reduction device | |
| JP4356604B2 (en) | VIDEO SIGNAL PROCESSING DEVICE, VIDEO SIGNAL PROCESSING METHOD, VIDEO SIGNAL PROCESSING PROGRAM, AND RECORDING MEDIUM CONTAINING VIDEO SIGNAL PROCESSING PROGRAM | |
| CN118483250A (en) | Wafer detection method and system | |
| JP2001186407A (en) | Image pickup device | |
| CN115499597A (en) | Method and device for identifying target frequency light source of imaging system and terminal equipment |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |