CN110213497A - A kind of method detection image flashing striping methods and adjust image exposuring time - Google Patents
A kind of method detection image flashing striping methods and adjust image exposuring time Download PDFInfo
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- CN110213497A CN110213497A CN201910402970.7A CN201910402970A CN110213497A CN 110213497 A CN110213497 A CN 110213497A CN 201910402970 A CN201910402970 A CN 201910402970A CN 110213497 A CN110213497 A CN 110213497A
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- 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
- H04N23/71—Circuitry for evaluating the brightness variation
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- 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
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Abstract
The present invention provides a kind of method detection image flashing striping methods and adjust image exposuring time, detection image flashing striping methods include: S110: acquiring continuous N frame image sequence, N is greater than 1 integer: S120: executing flicker frequency to each frame image in the continuous N frame image sequence and determines that step, flicker frequency determine that step includes: S121: obtaining the luminance channel image of present frame；S122: the row mean vector of consecutive frame image is calculated；S123: row difference value vector is calculated；S124: the average value of row difference value vector, the amplitude center of the waveform of the row difference value vector as current frame image are calculated；S125: position vector Pose (m) is determined；S126: flicker frequency of at least one predetermined flicker frequency as current frame image is determined from predetermined flicker frequency set；Step S130: according to predetermined flicker frequency each in predetermined flicker frequency set in the accounting of N frame image sequence, flicker frequency is determined.The present invention efficiently and accurately detects the presence flashed in image frame sequence and its frequency.
Description
Technical field
The present invention relates to image signal process more particularly to a kind of detection image flashing striping methods and adjustment image exposure
The method of time.
Background technique
In practical applications, when the environment light source for acquiring image is light, since the brightness of light is in cyclically-varying
(period of 50Hz (hertz) source power supply is 1/100 second；The period of 60Hz (hertz) source power supply is 1/120 second), so often
The initial time that one pixel or every one-row pixels receive exposure is inconsistent, causes acquired image brightness can be with exposure
The variation of line number generates periodically variation, and dynamic image, which is visually seen, has striped in surface flash.
The alternating current energy period of external environment light source (such as: incandescent lamp or fluorescent lamp) is 1/100 second or 1/120
Second, it is each on image if current exposure time is not the integral multiple of 1/100 second or 1/120 second when acquiring image
The energy of row accumulation is just different, shows as the striped of flashing in the picture.It, can be according to the frequency of light source in order to eliminate this flashing
Rate (i.e. alternating current energy period), such as: under 50Hz (pal mode) source power supply, the setting time for exposure is 1/100 second whole
Several times；Under 60Hz (NTSC system formula) source power supply, the integral multiple that the setting time for exposure is 1/120 second in this way may be used
To inhibit the flashing even being eliminated in acquisition image, but the premise of this method is to need to know the frequency of current light source, institute
To need to design the frequency that a kind of method is able to detect the presence and flashing that flash in image.
In the method for being traditionally used for detection flashing presence and its frequency, most of with DFT, (discrete fourier becomes
Change) find out the light frequency of current environment；Flashing variation coefficient is either found out in the time domain, with flicker factor adjustment image
Flash band；Or assume that current environment light frequency is 50Hz, the integral multiple in a 50Hz light source scintillation period is set, such as
There is also flashings for fruit, then are set as the integral multiple of 60Hz light source, to eliminate flashing.Such as all there is computation complexity in these methods
It is high, easy to be influenced big disadvantage by movement in image frame sequence, cause the Detection accuracy of flashing and recall rate not high.
Therefore, it is desirable to which a kind of flicker detection method, can reduce the computation complexity in conventional method, and can be smaller
Ground is influenced by moving in image frame sequence, thus efficiently and accurately detect the presence flashed in image frame sequence and its
Frequency.
Summary of the invention
The present invention provides a kind of detection image flashing striping methods and tune to overcome the problems of the above-mentioned prior art
The method of whole image exposuring time efficiently and accurately detects the presence flashed in image frame sequence and its frequency.
According to an aspect of the present invention, a kind of detection image flashing striping methods are provided, comprising:
Step S110: acquiring continuous N frame image sequence, and N is the integer greater than 1:
Step S120: executing flicker frequency to each frame image in the continuous N frame image sequence and determine step, described
Flicker frequency determines that step includes:
Step S121: the conversion of color space is carried out to current frame image, acquires the luminance channel figure of current frame image
Picture；
Step S122: the luminance channel image of current frame image and previous frame image is calculated in the row mean value in selection area
Vector, the row mean vector in the selection area as described in the luminance channel image of same frame image each pixel column be averaged
Pixel value is constituted；
Step S123: the row mean vector that the row mean vector of current frame image subtracts previous frame image is obtained into difference and is made
For row difference value vector；
Step S124: calculating the average value of the row difference value vector, the waveform of the row difference value vector as current frame image
Amplitude center；
Step S125: determine position vector Pose (m), wherein the position vector from the row difference of current frame image to
Amplitude is equal to position structure of the m point at the amplitude center in the waveform of the row difference value vector of current frame image in the waveform of amount
At m is the integer more than or equal to 0；
Step S126: according to the distance between consecutive points in m of the position vector Pose (m) point and predetermined flashing frequency
The comparison of the theoretical wavelength of the corresponding light source of each predetermined flicker frequency determines pre- from the predetermined flicker frequency set in rate set
Determine flicker frequency of the flicker frequency as current frame image；
Step S130: according to each predetermined flicker frequency in the predetermined flicker frequency set in the accounting of N frame image sequence,
Determine the flicker frequency of the N frame image sequence.
Optionally, in m point of the position vector Pose (m) the distance between consecutive points be based on flicker detection threshold value with
The comparison of the theoretical wavelength of the corresponding light source of each predetermined flicker frequency in predetermined flicker frequency set.
Optionally, the step S126 includes:
Institute's present frame is calculated according to the distance between consecutive points in m of the position vector Pose (m) point and this m point
The peak value vector Peak_vector (p) of the waveform of the row difference value vector of image, p are the wave of the row difference value vector of current frame image
The quantity of the peak point of shape, p are the integer more than or equal to 0；
If p is less than 2, it is determined that current frame image flicker free；
If p is equal to 2, range difference between two peak points is calculated in peak value vector Peak_vector (p), to described pre-
Determine each predetermined flicker frequency in flicker frequency set, calculates the half theory wave of the corresponding light source of the predetermined flicker frequency
The long difference with the range difference of described two peak points, it is when difference calculated is less than the flicker detection threshold value, this is pre-
Determine flicker frequency of the flicker frequency as current frame image；And
If p is greater than 2, the distance between adjacent peaks or adjacent trough in peak value vector Peak_vector (p) are calculated
Difference calculates the reason of the corresponding light source of the predetermined flicker frequency to each predetermined flicker frequency in the predetermined flicker frequency set
By the difference of wavelength and the distance between the adjacent peaks or adjacent trough difference, when difference calculated is less than the flashing
When detection threshold value, using the predetermined flicker frequency as the flicker frequency of current frame image.
Optionally, the distance between two wave crests or two troughs difference in the peak value vector Peak_vector (p)
Are as follows:
In the peak value vector Peak_vector (p) between the distance between any two adjacent peaks difference, each adjacent peaks
Range difference mean value, one in the poor mean value of the distance between the distance between any two adjacent troughs difference, each adjacent trough.
Optionally, the step S126 includes:
To each predetermined flicker frequency in the predetermined flicker frequency set, the corresponding light source of the predetermined flicker frequency is calculated
Theoretical wavelength and the position vector Pose (m) m point in difference between the distance between consecutive points, when calculated
When difference is less than the flicker detection threshold value, using the predetermined flicker frequency as the flicker frequency of current frame image.
Optionally, the distance between consecutive points are the position vector Pose in m point of the position vector Pose (m)
(m) in m point in the distance between any two consecutive points or m point of the position vector Pose (m) each consecutive points it
Between apart from mean value.
Optionally, the step S130 includes:
Flicker free frequency is calculated in the accounting of N frame image sequence；
By accounting, flicker free frequency of each predetermined flicker frequency in N frame image sequence in the predetermined flicker frequency set
It is determined as the flashing of the N frame image sequence in the maximum predetermined flicker frequency of the accounting of N frame image sequence or flicker free frequency
Frequency.
Optionally, multiple predetermined flicker frequencies that the predetermined flicker frequency set includes correspond to the light source of environment etc.
The frequency of the power supply alternating current energy of different systems.
Optionally, include: to the conversion of current frame image progress color space
Current frame image is converted to such as one of drag: YUV model, YIQ model, YCbCr model, YPbPr mould
Type, YDbDr model, HLS model, Lab model.
According to another aspect of the invention, a kind of side based on image flicker frequency adjustment image exposuring time is also provided
Method, comprising:
The flicker frequency of the N frame image sequence is determined using detection image as described above flashing striping methods；
It is the integral multiple of the corresponding flicker cycle of the flicker frequency based on the identified flicker frequency adjustment time for exposure.
Compared with the prior art, the invention has the following advantages:
The present invention by analyzing the flashing image of acquisition, find row difference value vector waveform between adjacent two frame with
The flicker cycle of light is approximately equal within a certain error range there are certain rule, i.e. wavelength in the two a cycle
, to determine flicker cycle based on row difference value vector waveform, the computation complexity in traditional algorithm is effectively reduced, is more suitable for
Realization on hardware, and can be influenced with lesser by moving scene in image frame sequence, there is better application value.
Detailed description of the invention
Its example embodiment is described in detail by referring to accompanying drawing, above and other feature of the invention and advantage will become
It is more obvious.
Fig. 1 is the energy diagram accumulated in sine wave signal of not going together in same frame provided in an embodiment of the present invention；
Fig. 2 is the Exposure mode schematic diagram of acquisition vision facilities provided in an embodiment of the present invention；
Fig. 3 is a kind of flow chart of detection image flashing striping methods provided in an embodiment of the present invention；
Fig. 4 is image of the two continuous frames with flashing on the channel Y provided in an embodiment of the present invention；
Fig. 5 is the row mean vector provided in an embodiment of the present invention for calculating Y_IMAGE image selection area；
Fig. 6 is row difference value vector wavelength figure compared with theoretical wavelength provided in an embodiment of the present invention；
Specific embodiment
Example embodiment is described more fully with reference to the drawings.However, example embodiment can be with a variety of shapes
Formula is implemented, and is not understood as limited to example set forth herein；On the contrary, thesing embodiments are provided so that the disclosure will more
Fully and completely, and by the design of example embodiment comprehensively it is communicated to those skilled in the art.Described feature, knot
Structure or characteristic can be incorporated in any suitable manner in one or more embodiments.
In addition, attached drawing is only the schematic illustrations of the disclosure, it is not necessarily drawn to scale.Identical attached drawing mark in figure
Note indicates same or similar part, thus will omit repetition thereof.Some block diagrams shown in the drawings are function
Energy entity, not necessarily must be corresponding with physically or logically independent entity.These function can be realized using software form
Energy entity, or these functional entitys are realized in one or more hardware modules or integrated circuit, or in heterogeneous networks and/or patrol
It collects in circuit device and/or microcontroller device and realizes these functional entitys.
Basic principle of the invention is as follows:
When the external environment light source for acquiring image is light, since alternating current is changed according to sine wave,
So the brightness that light generates can also change with the variation of sine wave, and further, the lamplight brightness L (t) of t moment
It can indicate are as follows:
Wherein, L indicate lamplight brightness peak value, f indicate alternating current energy frequency, i.e., 50Hz (pal mode,
Phase Alteration Line, line-by-line inversion) f under light sourcePAL=100Hz；60Hz (NTSC system formula, National
Television Standards Committee, (U.S.) National Television Standards Committee) f under light sourceNTSC=120Hz.
Assuming that the exposure starting time of the m row of n-th frame image is T1, end time T2, the exposure of m+1 row starts
Time is T1', end time T2', Fig. 1 shows this process；The exposure starting time of the m row of (n+1)th frame image is
T3, end time T4, therefore the time for exposure Expt=T of every a line2-T1=T4-T3, the exposure initial time of adjacent rows is poor
Different △ t=T1'-T1=T2'-T2, i.e. the readout time of the every a line of current frame image, Fig. 2 shows this processes.By above-mentioned lamp
Brightness formula can calculate m row light energy obtained in exposure process are as follows:
Assuming that adjacent two frame is T with the time interval of a linef=T4-T2=T3-T1, therefore same a line of adjacent two frame is made
Difference is available:
Wherein, L, f, Expt, TfIt is known, T under entire exposure systemfFor the wave period under light source frequency, so
It is available:
I.e. above formula can be adjusted to: row difference value vector E_Diffm=Ysin (KTm+t)
It is available from above-mentioned formula, same a line of adjacent two frame can be regarded as to one as difference shaped like Asin
The SIN function of (kx+ θ) is sampled, and the sampling interval is 2 △ t.Assuming that a cycle wavelength of 50Hz (pal mode) light
For PAL_period；The a cycle wavelength of 60Hz (NTSC system formula) light is NTSC_period.It therefore can be by above-mentioned formula
Find out the theoretical wavelength of a cycle, it may be assumed that
When environment light source is 50Hz (pal mode) light:
When environment light source is 60Hz (NTSC system formula) light:
Based on above-mentioned basic principle, the embodiment of the present invention is arrived by carrying out RGB color to acquired image
The conversion of YCbCr color space, to obtain the image in the channel Y, and the row found out between consecutive frame on the image in the channel Y is poor
It is worth vector；The amplitude center of its waveform is found out by row difference value vector；Further, calculate between adjacent amplitude central point away from
From the i.e. wavelength of a cycle or the wavelength of half period；Then the wavelength found out is passed through into flicker detection threshold value and 50Hz/
The theoretical wavelength of 60Hz frequency light source a cycle or half period compares, and calculates the flicker frequency of current light.
Fig. 3 is a kind of flow chart of detection image flashing striping methods provided in an embodiment of the present invention, specifically, Fig. 3
Include the following steps:
Step S110: acquiring continuous N frame image sequence, and N is the integer greater than 1.
Step S120: executing flicker frequency to each frame image in the continuous N frame image sequence and determine step, described
Flicker frequency determines that step includes:
Step S121: the conversion of color space is carried out to current frame image, acquires the luminance channel figure of current frame image
Picture.
Specifically, carrying out the conversion of color space to current frame image includes: to be converted to current frame image such as lower die
One of type: YUV model, YIQ model, YCbCr model, YPbPr model, YDbDr model, HLS model, Lab model.
Wherein, YUV model is color model used by eurovision system, and Y indicates luminance signal, and U, V indicate color difference
Signal.YIQ model is color model used by North American television system, and Y indicates luminance signal, and I and Q then refer to tone
(Chrominance), that is, the attribute of image color and saturation degree is described.YCbCr model be YUV compression and offset version
This, wherein Cb (blue) and Cr (red) indicates coloration, also abbreviation YCC model.YPbPr model is similar to YCbCr model, therewith not
With the cie color coordinate that YPbPr is selected is slightly different.The colour difference signal of general SDTV transmission is referred to as Cb, Cr, and
The colour difference signal of HDTV transmission is referred to as Pb, Pr.YDbDr model is similar to YCbCr model, and different, YDbDr is
Color model used in SECAM system formula television system.Current frame image is converted into YUV model, YIQ model, YCbCr as a result,
One of model, YPbPr model, YDbDr model, to acquire the Y channel image of current frame image.
Wherein, in HLS model, L indicates brightness (Lightness/Luminance/Intensity).Not according to abbreviation
Together, HLS is sometimes referred to as HSL or HSI (that is HSL, HLS, HIS are identical models).In Lab model, L * component is used for table
Show the brightness of pixel, indicates from black to pure white；A indicates the range from red to green；B indicates the model from yellow to blue
It encloses.Current frame image is converted into one of HLS model, Lab model as a result, to acquire the channel the L figure of current frame image
Picture.
It is above only to be illustratively described multiple implementations of color space conversion of the invention, but the present invention is not
As limit, the present invention can be using the arbitrary model with luminance channel image, and it will not be described here.
Step S122: the luminance channel image of current frame image and previous frame image is calculated in the row mean value in selection area
Vector, the row mean vector in the selection area as described in the luminance channel image of same frame image each pixel column be averaged
Pixel value is constituted.
Step S123: the row mean vector that the row mean vector of current frame image subtracts previous frame image is obtained into difference and is made
For row difference value vector.
Step S124: calculating the average value of the row difference value vector, the waveform of the row difference value vector as current frame image
Amplitude center.
Step S125: determine position vector Pose (m), wherein the position vector from the row difference of current frame image to
Amplitude is equal to position structure of the m point at the amplitude center in the waveform of the row difference value vector of current frame image in the waveform of amount
At m is the integer more than or equal to 0.
Step S126: according to the distance between consecutive points in m of the position vector Pose (m) point and predetermined flashing frequency
The comparison of the theoretical wavelength of the corresponding light source of each predetermined flicker frequency determines pre- from the predetermined flicker frequency set in rate set
Determine flicker frequency of the flicker frequency as current frame image.
The distance between consecutive points are based on flicker detection threshold value and predetermined sudden strain of a muscle in m point of the position vector Pose (m)
The comparison of the theoretical wavelength of the corresponding light source of each predetermined flicker frequency in bright frequency sets.
In a specific embodiment, the step S126 may include:
It is calculated according to the distance between consecutive points in m of the position vector Pose (m) point and this m point described current
The peak value vector Peak_vector (p) of the waveform of the row difference value vector of frame image, p are the row difference value vector of current frame image
The quantity of the peak point of waveform, p are the integer more than or equal to 0；
If p is less than 2, it is determined that current frame image flicker free；
If p is equal to 2, range difference between two peak points is calculated in peak value vector Peak_vector (p), to described pre-
Determine each predetermined flicker frequency in flicker frequency set, calculates the half theory wave of the corresponding light source of the predetermined flicker frequency
The long difference with the range difference of described two peak points, it is when difference calculated is less than the flicker detection threshold value, this is pre-
Determine flicker frequency of the flicker frequency as current frame image；And
If p is greater than 2, the distance between adjacent peaks or adjacent trough in peak value vector Peak_vector (p) are calculated
Difference calculates the reason of the corresponding light source of the predetermined flicker frequency to each predetermined flicker frequency in the predetermined flicker frequency set
By the difference of wavelength and the distance between the adjacent peaks or adjacent trough difference, when difference calculated is less than the flashing
When detection threshold value, using the predetermined flicker frequency as the flicker frequency of current frame image.
Wherein, the distance between two wave crests or two troughs difference in the peak value vector Peak_vector (p) are as follows:
The distance between the distance between any two adjacent peaks difference, each adjacent peaks difference in the peak value vector Peak_vector (p)
One in the distance between the distance between mean value, any two adjacent troughs difference, each adjacent trough difference mean value.The position to
Measuring the distance between consecutive points in the m point of Pose (m) is any two consecutive points in m point of the position vector Pose (m)
The distance between or m point of the position vector Pose (m) in the distance between each consecutive points mean value.
In another realization of the step, the step S126 may include: in the predetermined flicker frequency set
Each predetermined flicker frequency, calculate the corresponding light source of the predetermined flicker frequency theoretical wavelength and the position vector Pose (m)
M point in difference between the distance between consecutive points, when difference calculated is less than the flicker detection threshold value, by this
Flicker frequency of the predetermined flicker frequency as current frame image.
Wherein, the distance between consecutive points are the position vector Pose in m point of the position vector Pose (m)
(m) in m point in the distance between any two consecutive points or m point of the position vector Pose (m) each consecutive points it
Between apart from mean value.
Step S130: according to each predetermined flicker frequency in the predetermined flicker frequency set in the accounting of N frame image sequence,
Determine the flicker frequency of the N frame image sequence.
Specifically, step S130 can include: to calculate flicker free frequency in the accounting of N frame image sequence with volume；It will be described
Each predetermined flicker frequency is in the accounting of N frame image sequence, flicker free frequency in N frame image sequence in predetermined flicker frequency set
The maximum predetermined flicker frequency of accounting or flicker free frequency are determined as the flicker frequency of the N frame image sequence.
Summarize in each embodiment of the invention, multiple predetermined flicker frequencies pair that the predetermined flicker frequency set includes
It should be in the frequency of the power supply alternating current energy of the different systems of the light source of environment etc..
A specific implementation of the invention is described below with reference to each attached drawing.In the present embodiment, make a reservation for flashing frequency
Rate set includes the frequency of the frequency of the power supply alternating current energy of pal mode and the power supply alternating current energy of NTSC system formula.
Firstly, to collected continuous N frame image carry out RGB color to YCbCr color space conversion (only
For the sake of schematically, system is not limited thereto in the present invention), and the image in the channel Y is extracted, it is denoted as Y_IMAGE (n), n=1,2,
3,…,N.And the width for assuming image is Width, is highly Height.Fig. 4 shows the realization of this process.
Capable to Y_IMAGE (n) image selection R (0 < R≤Width) of C (0 < C≤Height) column, calculate present frame figure
As the average value of the channel the Y pixel value of a line every in selection area, and by every a line calculated average value according to capable
Sequence constitutes row mean vector Row_avg (n), and Fig. 5 shows the realization of this process.
Then, the row difference value vector Diff_row_avg between consecutive frame is sought.
That is: the row difference value vector Diff_row_avg of present frame subtracts the row difference value vector Diff_row_ of previous frame image
Avg:Diff_row_avgi=Row_avgi(n)-Row_avgi(n-1), [i=1,2,3 ..., R], Fig. 6 shows row difference
(in Fig. 6, dotted line is the amplitude center line that the value at amplitude center is formed to the waveform of vector, and solid line is the waveform of row difference value vector, empty
Line is the theoretical waveform of pal mode, and chain-dotted line is the theoretical waveform of NTSC system formula).
Then, it averages to row difference value vector, obtains the amplitude center of row difference value vector.That is:
The position of the point equal to amplitude center Diff_AmpCenter is found out from row difference value vector, in Fig. 6 row difference to
The waveform of amount and the intersection point of amplitude center line are the position of amplitude central point, and are denoted as position vector Pose (m) by capable sequence,
M indicates the number for being equal to the point at amplitude center, and m is the integer more than or equal to 0.And it is asked from position vector Pose (m) vector
Out in each point of amplitude center consecutive points distance, i.e. the wavelength of a cycle or half period is denoted as Dist.That is:
Dist=Pose (k)-pose (k-1), [k=2,3 ..., m].
Assuming that PCLK (MHz), the picture traverse Width of present image acquisition equipment are it is known that and it is known that pal mode quotient
Frequency with power supply alternating current energy is fPAL=100Hz, the frequency of NTSC system formula source power supply alternating current energy are fNTSC
=120Hz, therefore the wavelength PAL_period of a cycle of pal mode and a week of NTSC system formula can be calculated separately out
The wavelength NTSC_period of phase, it may be assumed that
PAL_period=1/ (△ tf)=(PCLK*106)/(Width*PAL_HZ)；
NTSC_period=1/ (△ tf)=(PCLK*106)/(Width*NTSC_HZ)；
Pal mode and the theoretical waveform of NTSC system formula are also shown in FIG. 6.
Assuming that flicker detection threshold value is flicker_th.Some in the specific implementation, can be by PAL_period, NTSC_
Period and flicker detection threshold value find out the upper threshold value Period_half_th_high of half period flicker detection, half period flashing
Lower threshold value Period_half_th_low, the upper threshold value Period_full_th_high of complete period flicker detection, complete cycle of detection
The lower threshold value Period_full_th_low of phase flicker detection, it may be assumed that
Period_half_th_high=NTSC_period/2；
Period_half_th_low=PAL_period/4；
Period_full_th_high=NTSC_period；
Period_full_th_low=PAL_period；
During distance Dist and flicker detection threshold value are compared, the present invention provides two kinds of specific implementations.
At the first in the specific implementation, by amplitude center consecutive points distance Dist and half period flicker detection up/down threshold value
Compare, i.e., when Period_half_th_low≤Dist≤Period_half_th_high (if Dist not in this range when
Judge that this frame does not flash, and the peak value vector Peak_ in a cycle is arranged from when adding 1) in NO_flicker_cnt
Vector (p), wherein p indicates the number of peak point (wave crest and trough) in row difference value vector, calculates the peak point in the half period,
And it is stored in peak value vector, it may be assumed that
Peak_vector (i)=pose (k-1)+(Dist/2), [i=1,2,3..., p]
As the number p < 2 at the midpoint peak value vector Peak_vector, the flicker frequency of current frame image can not be judged, i.e.,
The image frame counter NO_flicker_cnt for thinking that present frame does not flash, and not flashing adds 1 certainly.
As the number p=2 at the midpoint peak value vector Peak_vector, the distance Peak_ of adjacent peak point is calculated
Dist, it may be assumed that
Peak_dist=Peak_vector (2)-Peak_vector (1)
Peak_dist and flicker_th are compared, as Peak_dist- (PAL_period/2) < flicker_th
When, judge the flicker frequency of current frame image for 50Hz light source, i.e. pal mode, and the picture frame meter of 50Hz light source frequency
Number device PAL_cnt adds 1 certainly；As Peak_dist- (NTSC_period/2) < flicker_th, the sudden strain of a muscle of current frame image is judged
Bright frequency is 60Hz light source, i.e. NTSC system formula, and the image frame counter NTSC_cnt of 60Hz light source frequency adds 1 certainly；It is no
The flicker frequency that can not then judge current frame image, i.e., do not flash, and the image frame counter NO_flicker_ not flashed
Cnt is certainly plus 1 (specifically, above-mentioned two inequality is judged in order, does the judgement of pal mode first, is such as unsatisfactory for again
The judgement for doing NTSC system formula, such as has not been met, and output does not flash).
As the number p > 2 at the midpoint peak value vector Peak_vector, the distance Peak_ of adjacent trough or wave crest is calculated
Dist, it may be assumed that
Peak_dist=Peak_vector (3)-Peak_vector (1)
Peak_dist and flicker_th are compared, as Peak_dist-PAL_period < flicker_th, sentenced
The flicker frequency of disconnected current frame image is 50Hz light source, i.e. pal mode, and the image frame counter of 50Hz light source frequency
PAL_cnt adds 1 certainly；As Peak_dist-NTSC_period < flicker_th, judge that the flicker frequency of current frame image is
60Hz light source, i.e. NTSC system formula, and the image frame counter NTSC_cnt of 60Hz light source frequency adds 1 certainly；Otherwise can not sentence
The flicker frequency of disconnected current frame image, i.e., the image frame counter NO_flicker_cnt for not flashing, and not flashing add 1 certainly
(specifically, above-mentioned two inequality is judged in order, the judgement of pal mode is done first, is such as unsatisfactory for doing NTSC again
The judgement of standard, such as has not been met, and output does not flash).
At second in the specific implementation, by amplitude center consecutive points distance Dist and complete period flicker detection up/down threshold value
Compare, i.e., when Period_full_th_low≤Dist≤Period_full_th_high (if Dist not in this range when
Judge that this frame does not flash, and Dist and flicker_th are compared from when adding 1), work as Dist- by NO_flicker_cnt
When PAL_period < flicker_th, judge the flicker frequency of current frame image for 50Hz light frequency, i.e. pal mode, and
The image frame counter PAL_cnt of 50Hz light source frequency adds 1 certainly；As Dist-NTSC_period < flicker_th, judgement is worked as
The flicker frequency of prior image frame is 60Hz light source, i.e. NTSC system formula, and the image frame counter NTSC_ of 60Hz light source frequency
Cnt adds 1 certainly；Otherwise the flicker frequency that can not judge current frame image, i.e., do not flash, and the image frame counter not flashed
NO_flicker_cnt is certainly plus 1 (specifically, above-mentioned two inequality is judged that pal mode is sentenced first in order
It is disconnected, be such as unsatisfactory for doing the judgement of NTSC system formula again, such as have not been met, output does not flash).
As can be seen that the flashing of current frame image from the row difference value vector wavelength shown in Fig. 6 is compared with theoretical wavelength
Frequency within an acceptable error range (i.e. detection threshold value), phase approximate with the theoretical waveform of 50Hz (pal mode) frequency light
Deng so judging the ambient light light frequency of current frame image for 50Hz.
Then, it finds out in continuous N frame image, 50Hz frequency image, 60Hz frequency image, flicker free three types are respective
Account for the percentage of totalframes, it may be assumed that
X%=(PAL_cnt/N) * 100%；
Y%=(NTSC_cnt/N) * 100%；
Z%=(No_flicker_cnt/N) * 100%；
In step S108, compare X%, Y%, the size between Z% three is worked as X% > Y% and X% > Z%, judged
Current environment light frequency is 50Hz；Work as Y% > X% and Y% > Z%, judges current environment light frequency for 60Hz；Otherwise judge
Current environment is lamp.
Above is only schematically to describe a specific implementation of the invention, and the present invention is not limited thereto.
According to another aspect of the invention, a kind of side based on image flicker frequency adjustment image exposuring time is also provided
Method comprising following steps: the flashing of the N frame image sequence is determined using detection image as described above flashing striping methods
Frequency；It is the integral multiple of the corresponding flicker cycle of the flicker frequency based on the identified flicker frequency adjustment time for exposure.
Specifically, acquisition vision facilities can be adjusted according to the flicker frequency of above-mentioned calculated current environment light
Time for exposure, when ambient light light frequency is 50Hz, the adjustment time for exposure is 1/100 second integral multiple；When ambient light optical frequency
When rate is 60Hz, the integral multiple that the time for exposure is 1/120 second is adjusted；Otherwise not having to the adjustment time for exposure, (i.e. current light source is certainly
Right light source), to achieve the effect that suppress or eliminate image flicker.
Compared with the prior art, the invention has the following advantages:
The present invention by analyzing the flashing image of acquisition, find row difference value vector waveform between adjacent two frame with
The flicker cycle of light is approximately equal within a certain error range there are certain rule, i.e. wavelength in the two a cycle
, to determine flicker cycle based on row difference value vector waveform, the computation complexity in traditional algorithm is effectively reduced, is more suitable for
Realization on hardware, and can be influenced with lesser by moving scene in image frame sequence, there is better application value.
Those skilled in the art after considering the specification and implementing the invention disclosed here, will readily occur to its of the disclosure
Its embodiment.This application is intended to cover any variations, uses, or adaptations of the disclosure, these modifications, purposes or
Person's adaptive change follows the general principles of this disclosure and including the undocumented common knowledge in the art of the disclosure
Or conventional techniques.The description and examples are only to be considered as illustrative, and the true scope and spirit of the disclosure are by appended
Claim is pointed out.
Claims (10)
1. a kind of detection image flashes striping methods characterized by comprising
Step S110: acquiring continuous N frame image sequence, and N is the integer greater than 1:
Step S120: flicker frequency is executed to each frame image in the continuous N frame image sequence and determines step, the flashing
Frequency determines that step includes:
Step S121: the conversion of color space is carried out to current frame image, acquires the luminance channel image of current frame image；
Step S122: calculate the luminance channel image of current frame image and previous frame image in the row mean value in selection area to
Amount, the average picture of the row mean vector each pixel column in the selection area as described in the luminance channel image of same frame image
Element value is constituted；
Step S123: the row mean vector that the row mean vector of current frame image subtracts previous frame image is obtained into difference as row
Difference value vector；
Step S124: calculating the average value of the row difference value vector, the width of the waveform of the row difference value vector as current frame image
Degree center；
Step S125: determine position vector Pose (m), wherein the position vector by current frame image row difference value vector
Amplitude is equal to position of the m point at the amplitude center in the waveform of the row difference value vector of current frame image and constitutes in waveform, m
For the integer more than or equal to 0；
Step S126: according to the distance between consecutive points in m of the position vector Pose (m) point and predetermined flicker frequency collection
The comparison of the theoretical wavelength of the corresponding light source of each predetermined flicker frequency determines predetermined dodge from the predetermined flicker frequency set in conjunction
Bright flicker frequency of the frequency as current frame image；
Step S130: it according to each predetermined flicker frequency in the predetermined flicker frequency set in the accounting of N frame image sequence, determines
The flicker frequency of the N frame image sequence.
2. detection image as described in claim 1 flashes striping methods, which is characterized in that the m of the position vector Pose (m)
It is corresponding with each predetermined flicker frequency in predetermined flicker frequency set to be based on flicker detection threshold value for the distance between consecutive points in a point
Light source theoretical wavelength comparison.
3. detection image as claimed in claim 2 flashes striping methods, which is characterized in that the step S126 includes:
The present frame figure is calculated according to the distance between consecutive points in m of the position vector Pose (m) point and this m point
The peak value vector Peak_vector (p) of the waveform of the row difference value vector of picture, p are the waveform of the row difference value vector of current frame image
Peak point quantity, p is integer more than or equal to 0；
If p is less than 2, it is determined that current frame image flicker free；
If p is equal to 2, range difference between two peak points is calculated in peak value vector Peak_vector (p), to the predetermined sudden strain of a muscle
Each predetermined flicker frequency in bright frequency sets, calculate the half theoretical wavelength of the corresponding light source of the predetermined flicker frequency with
The difference of the range difference of described two peak points, when difference calculated is less than the flicker detection threshold value, by the predetermined sudden strain of a muscle
Bright flicker frequency of the frequency as current frame image；And
If p is greater than 2, the distance between adjacent peaks or adjacent trough difference in peak value vector Peak_vector (p) are calculated,
To each predetermined flicker frequency in the predetermined flicker frequency set, the theoretical wave of the corresponding light source of the predetermined flicker frequency is calculated
The long difference with the distance between the adjacent peaks or adjacent trough difference, when difference calculated is less than the flicker detection
When threshold value, using the predetermined flicker frequency as the flicker frequency of current frame image.
4. detection image as claimed in claim 3 flashes striping methods, which is characterized in that the peak value vector Peak_
The distance between two wave crests or two troughs difference in vector (p) are as follows:
In the peak value vector Peak_vector (p) between the distance between any two adjacent peaks difference, each adjacent peaks away from
One in the distance between the distance between deviation mean value, any two adjacent troughs difference, each adjacent trough difference mean value.
5. detection image as claimed in claim 2 flashes striping methods, which is characterized in that the step S126 includes:
To each predetermined flicker frequency in the predetermined flicker frequency set, the reason of the corresponding light source of the predetermined flicker frequency is calculated
By the difference between the distance between consecutive points in wavelength and m point of the position vector Pose (m), when difference calculated
When less than the flicker detection threshold value, using the predetermined flicker frequency as the flicker frequency of current frame image.
6. detection image as claimed in claim 3 or 5 flashes striping methods, which is characterized in that the position vector Pose (m)
M point in the distance between consecutive points be the distance between any two consecutive points in m point of the position vector Pose (m)
Or the distance between each consecutive points mean value in m point of the position vector Pose (m).
7. as detection image described in any one of claim 1 to 5 flashes striping methods, which is characterized in that the step S130
Include:
Flicker free frequency is calculated in the accounting of N frame image sequence；
By each predetermined flicker frequency in the predetermined flicker frequency set in the accounting of N frame image sequence, flicker free frequency in N frame
The maximum predetermined flicker frequency of the accounting of image sequence or flicker free frequency are determined as the flicker frequency of the N frame image sequence.
8. as detection image described in any one of claim 1 to 5 flashes striping methods, which is characterized in that the predetermined flashing
Multiple predetermined flicker frequencies that frequency sets include correspond to the power supply alternating current energy of the different systems of the light source of environment etc.
Frequency.
9. as detection image described in any one of claim 1 to 5 flashes striping methods, which is characterized in that current frame image
Carry out color space conversion include:
Current frame image is converted to such as one of drag: YUV model, YIQ model, YCbCr model, YPbPr model,
YDbDr model, HLS model, Lab model.
10. a kind of method based on image flicker frequency adjustment image exposuring time characterized by comprising
The sudden strain of a muscle of the N frame image sequence is determined using detection image as described in any one of claim 1 to 9 flashing striping methods
Bright frequency；
It is the integral multiple of the corresponding flicker cycle of the flicker frequency based on the identified flicker frequency adjustment time for exposure.
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