CN103905737B - Backlighting detecting and device - Google Patents

Backlighting detecting and device Download PDF

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Publication number
CN103905737B
CN103905737B CN201210572564.3A CN201210572564A CN103905737B CN 103905737 B CN103905737 B CN 103905737B CN 201210572564 A CN201210572564 A CN 201210572564A CN 103905737 B CN103905737 B CN 103905737B
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backlight
gray scale
environment
gray
image
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CN103905737A (en
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刘思翔
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Lenovo Beijing Ltd
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Lenovo Beijing Ltd
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Abstract

There is provided a kind of backlighting detecting and device.The backlighting detecting includes:Gather an image;Extract the grey level histogram of described image;And determine whether current environment is backlight environment according to the grey level histogram.Backlight detection is simply carried out based on acquired image in the case of without CMOS backlight detection sensors, so as to advantageously reduce the cost of backlight detection, and and then the cost of the electronic equipment using the backlighting detecting and device is reduced.

Description

Backlighting detecting and device
Technical field
The present invention relates to backlight environment measuring, and relate more specifically to a kind of backlighting detecting and device.
Background technology
At present, the application of digital camera is more and more extensive.In addition to the digital camera product of specialty, set in numerous electronics The standby upper digital camera for being integrated with different accuracy.For example, digital camera head is integrated with mostly in notebook computer, In personal digital assistant(PDA)Be integrated with digital camera mostly in smart mobile phone, digital phase is also integrated with tablet personal computer Machine.
When carrying out image taking using digital camera, inevitably run into backlight scene and shoot and non-backlight scene The problem of shooting., it is necessary to adjust the acquisition parameters of digital camera, to suppress, subject is excessively dark and background is excessively bright under backlight scene. The acquisition parameters generally comprise F-number, time for exposure etc..
CMOS backlight detection sensors are frequently included in existing digital camera, and biography is detected using the CMOS backlight Sensor carrys out the shooting state of automatic detection backlight., can be with adjust automatically acquisition parameters when digital camera detects backlight environment It is excessively bright to suppress subject dark and background excessively.
As digital camera is applied in various electronic equipments more and more, in order to reduce electronic equipment as much as possible Manufacturing cost, the cost for how reducing digital camera is also increasingly taken seriously.Therefore, the present invention desirable to provide one kind in nothing The method for needing to carry out backlight environment estimation in the case of CMOS backlight detection sensors, so that in digital camera or even various electronics Even if also not resulting in high-quality shooting image including CMOS backlight detection sensor in equipment.
The content of the invention
In view of above mentioned problem, the present invention has been made.The present invention is intended to provide a kind of backlighting detecting and device, its Backlight detection is directly carried out according to the image currently gathered in the case of without CMOS backlight detection sensors.As a result, May be according to the backlight testing result adjust automatically acquisition parameters.
According to an aspect of the present invention there is provided a kind of backlighting detecting, including:Gather an image;Extract described image Grey level histogram;And determine whether current environment is backlight environment according to the grey level histogram.
Preferably, in the backlighting detecting, determine whether current environment is backlight according to the grey level histogram Environment includes:Calculate the variance of the grey level histogram of described image;And determine whether current environment is inverse according to the variance Luminous environment.
Preferably, in the backlighting detecting, determine whether current environment is backlight according to the grey level histogram Environment includes:Determine whether current environment is backlight ring according to the local peaking of gray probability distribution in the grey level histogram Border, wherein, the gray scale at the place of local peaking being distributed in the gray probability is less than the first gray scale or during more than the second gray scale, really Current environment is determined for backlight environment;And the gray scale at the local peaking that the gray probability is distributed is more than the 3rd gray scale and small When four gray scales, it is non-backlight environment to determine current environment, wherein, first gray scale is less than or equal to the 3rd gray scale, described 3rd gray scale is less than the 4th gray scale, and the 4th gray scale is less than or equal to second gray scale.
Preferably, in the backlighting detecting, the image is coloured image, extracts the grey level histogram bag of the image Include:Convert the image to gray level image;And extract the grey level histogram of the gray level image.
Preferably, in the backlighting detecting, determine whether current environment is backlight environment bag according to the variance Include:Backlight degree is determined according to the variance;And when the backlight degree is more than predetermined threshold, it is backlight ring to determine current environment Border.
Preferably, in the backlighting detecting, determine whether current environment is backlight environment bag according to the variance Include:Backlight degree is determined according to the variance;And the probability that current environment is backlight environment is determined according to the backlight degree.
Preferably, in the backlighting detecting, according to the variance determine current environment whether be backlight environment also Including:When identified probability is more than predetermined probability threshold value, it is backlight environment to determine current environment.
Preferably, in the backlighting detecting, methods described also includes:By the probability with passing through another method meter The backlight ambient probability combination of calculation, to determine whether current environment is backlight environment.
According to a further aspect of the invention there is provided a kind of backlight detection means, including:Image acquisition component, for obtaining Image, the image is the image shot under the present circumstances;Histogram extracting parts, the intensity histogram for extracting described image Figure;And informating part, for determining whether the current environment is backlight environment according to the grey level histogram.
Preferably, the informating part includes:Variance calculating unit, the side of the grey level histogram for calculating described image Difference;And environment determines part, for determining whether current environment is backlight environment according to the variance.
Preferably, the informating part determines to work as according to the local peaking of gray probability distribution in the grey level histogram Whether preceding environment is backlight environment, wherein, the gray scale at the place of local peaking being distributed in the gray probability less than the first gray scale or When person is more than the second gray scale, the informating part determines that current environment is backlight environment;And be distributed in the gray probability When gray scale at local peaking is more than the 3rd gray scale and is less than four gray scales, the informating part determines that current environment is non-backlight Environment, wherein, first gray scale is less than or equal to the 3rd gray scale, and the 3rd gray scale is less than the 4th gray scale, the 4th gray scale Less than or equal to second gray scale.
Preferably, the backlight detection means also includes:Image converting member, for when described image is coloured image The coloured image is converted into gray level image, wherein, the gray scale that the histogram extracting parts extracts the gray level image is straight Fang Tu.
Preferably, the environment determines that part includes:Backlight degree calculating unit, for determining backlight according to the variance Degree, and backlight determine part, for determining that current environment is backlight environment when the backlight degree is more than predetermined threshold.
Preferably, the environment determines that part includes:Backlight degree calculating unit, for determining backlight according to the variance Degree;Backlight ambient probability calculating unit, for determining probability of the current environment for backlight environment according to the backlight degree;And it is inverse Light determines part, for determining that current environment is backlight environment when identified probability is more than predetermined probability threshold value.
Preferably, the environment determines that part includes:Backlight degree calculating unit, for determining backlight according to the variance Degree;Backlight ambient probability calculating unit, for determining probability of the current environment for backlight environment according to the backlight degree;And it is inverse Light determines part, for identified probability to be combined with the backlight ambient probability calculated by another method, current to determine Whether environment is backlight environment.
Preferably, in the backlighting detecting and device, the grey level histogram includes multiple gray scales and each Pixel quantity corresponding to gray scale, or the grey level histogram are normalized grey level histogram, the normalized gray scale Histogram includes the probability of occurrence corresponding to multiple gray scales and each gray scale.
, can be without CMOS backlight detection sensors using backlighting detecting and device according to embodiments of the present invention In the case of backlight detection is simply carried out based on acquired image so that advantageously reduce backlight detection cost, and And then reduce the cost of the electronic equipment using the backlighting detecting and device.
Brief description of the drawings
According to embodiments of the present invention by reference to accompanying drawing description, the various features and advantage of the embodiment of the present invention will be brighter It is aobvious, and be also easier to be understood, in the accompanying drawings:
The flow chart of backlighting detecting according to embodiments of the present invention Fig. 1;
Fig. 2 shows the specific of the first sample implementation of the step S130 in Fig. 1 according to embodiments of the present invention Flow chart;
Fig. 3 shows the specific of second of sample implementation of the step S130 in Fig. 1 according to embodiments of the present invention Flow chart;
Fig. 4 shows the specific of the third sample implementation of the step S130 in Fig. 1 according to embodiments of the present invention Flow chart;
Fig. 5 shows the specific of the 4th kind of sample implementation of the step S130 in Fig. 1 according to embodiments of the present invention Flow chart;
Fig. 6 shows the schematic block diagram of backlight detection means according to embodiments of the present invention;
Fig. 7 A show the grey level histogram distribution under exemplary backlight environment;
Fig. 7 B show the grey level histogram distribution under exemplary non-backlight environment;And
Fig. 8 shows the curve map of exemplary backlight degree and backlight ambient probability.
Embodiment
Backlighting detecting and electronic equipment according to embodiments of the present invention described below with reference to the accompanying drawings.
In Fig. 7 A and Fig. 7 B, grey level histogram distribution and the non-backlight ring under exemplary backlight environment are respectively illustrated Grey level histogram distribution under border, wherein transverse axis represents gray scale.
Under a kind of sample situation, grey level histogram can be embodied between each gray scale and pixel count corresponding to each gray scale Relation histogram, in the case, grey level histogram include multiple gray scales(Such as 128,256,512 gray scales Deng)And the pixel quantity corresponding to each gray scale.In the case, Fig. 7 A and Fig. 7 B longitudinal axis represent pixel quantity.
Under another sample situation, grey level histogram can be normalized grey level histogram, the normalized ash The relation between probability of occurrence corresponding to degree histogram each gray scale of embodiment and each gray scale, in the case, grey level histogram bag Include multiple gray scales(Such as 128,256,512 gray scales etc.)And the probability of occurrence corresponding to each gray scale, it is described go out Existing probability can be the ratio between pixel count and total pixel number corresponding to each gray scale.In the case, Fig. 7 A and Fig. 7 B longitudinal axis Represent the probability of occurrence of each gray scale.
As can be seen that the grey level histogram distribution under backlight environment and the gray scale under non-backlight environment from Fig. 7 A and Fig. 7 B Histogram distribution is entirely different.As shown in Figure 7 A, the characteristics of grey level histogram under backlight environment is distributed is:It is distributed in incandescent It is many with pixel in very dark gray scale, and it is relatively fewer to be distributed in the pixel in middle gray.In contrast, as shown in Figure 7 B, it is non- Grey level histogram distribution under backlight environment is characterised by:Pixel is concentrated mainly in middle gray, and be distributed in incandescent and Pixel in very dark gray scale is considerably less.As can be seen here, the grey level histogram distribution under backlight environment and the ash under non-backlight environment There is significant difference in degree histogram distribution.
Although only giving grey level histogram distribution and the non-backlight under exemplary backlight environment in Fig. 7 A and Fig. 7 B Grey level histogram distribution under environment, and for different photographed scenes, the grey level histogram distribution under backlight environment may It is not quite similar, and for different photographed scenes, the grey level histogram distribution under non-backlight environment is also not quite similar, but nothing By being that grey level histogram distribution under backlight environment is also grey level histogram distribution under non-backlight environment, good system is respectively provided with Count characteristic.That is, the characteristics of grey level histogram under backlight environment is distributed is:It is distributed in the pixel on incandescent and very dark gray scale It is many, and it is relatively fewer to be distributed in the pixel in middle gray;Grey level histogram distribution under non-backlight environment is characterised by:Picture Element is concentrated mainly in middle gray, and the pixel being distributed on incandescent and very dark gray scale is considerably less.
In view of above-mentioned characteristic, a kind of method based on image to carry out backlight detection in itself is inventors herein proposed.
First, backlighting detecting 100 according to embodiments of the present invention will be described with reference to Figure 1.According to present invention implementation The backlighting detecting 100 of example starts in step S101.
In step S110, image is gathered.Gathering image can include gathering image with exposal model, or with image pickup mode Image is gathered, or image is gathered with preview mode.In addition, collection image can include storage image or non-storage image.Example Such as, collection image can be included in focused when taking pictures during gather image and store or not storage image, can include Image is gathered under preview mode and is stored or not storage image, can be included under image pickup mode and be gathered image and store Image.Gather image in addition, collection image can be included under default backlight detection pattern and store or not storage image.
In step S120, the grey level histogram of acquired image is extracted.Acquired image can be gray level image or Coloured image.In the case where acquired image is coloured image, acquired image first can be converted into gray level image. Then, then based on gray level image extract grey level histogram.It is people in the art how coloured image to be converted into gray level image Member is known, therefore omits its specific descriptions herein.
How to travel through each pixel of acquired image with extract grey level histogram be also well known to a person skilled in the art, because This also omits its specific descriptions herein.
In step S130, determine whether current environment is backlight environment according to the grey level histogram.Specifically, according to institute The feature of grey level histogram is stated to determine whether current environment is backlight environment.
As it was previously stated, the grey level histogram under backlight environment is the characteristics of distribution:It is distributed on incandescent and very dark gray scale Pixel it is many, and it is relatively fewer to be distributed in the pixel in middle gray;The feature of grey level histogram distribution under non-backlight environment It is:Pixel is concentrated mainly in middle gray, and the pixel being distributed on incandescent and very dark gray scale is considerably less.
In addition, in terms of statistical property, be distributed for the grey level histogram under backlight environment, the distribution of its grey level histogram Gray variance σ2It is very big;And be distributed for the grey level histogram under non-backlight environment, the gray variance σ of its grey level histogram distribution2 Very little.
Then, in step S199, backlighting detecting 100 according to embodiments of the present invention terminates.
Assuming that acquired image I normalized grey level histogram is X=(x1,x2,…,x256)T, wherein xiRepresent i-th The probability that individual gray scale occurs in acquired image I.
Next, based on the normalized grey level histogram, backlight according to embodiments of the present invention will be illustrated and detected Step S130 specific implementation in method 100.
The tool of the first sample implementation of step S130 in Fig. 1 according to embodiments of the present invention is shown in Fig. 2 Body flow chart.
In the first sample implementation, the local peaking being distributed according to gray probability in the grey level histogram is come really Whether determine current environment is backlight environment.
In step S2310, the local peaking that gray probability is distributed in the grey level histogram is determined.Moreover, correspondingly true Gray scale corresponding to the fixed local peaking.With reference to Fig. 7 A, identified local peaking can be corresponding to such as gray value 3 Gray probability and the gray probability for example corresponding to gray value 250.
Then, in step S2320, determine whether the gray scale at the local peaking of the gray probability distribution is less than the first ash Spend or more than the second gray scale.
Gray scale at the local peaking for determining the gray probability distribution in step S2320 is less than the first gray scale or big When the second gray scale, in step S2330, it is backlight environment to determine current environment.For example, still with Fig. 7 A, first gray scale Can be, for example, gray value 30, second gray scale can be such as gray value 180, identified local peaking(Gray value 3) Less than first gray scale, and identified local peaking(Gray value 250)More than second gray scale, therefore, the image Current environment be confirmed as backlight environment.
When the gray scale at the place of local peaking that gray probability distribution is determined in step S2320 be not less than the first gray scale and During no more than the second gray scale, the backlighting detecting proceeds to step S2340.
In step S2340, determine the gray probability distribution place of local peaking gray scale whether more than the 3rd gray scale and Less than the 4th gray scale.
Gray scale at the local peaking for determining the gray probability distribution in step S2340 is more than the 3rd gray scale and is less than During four gray scales, in step S2350, it is non-backlight environment to determine current environment, for example, with reference to Fig. 7 B, the 3rd gray scale can To be, for example, gray value 80, the 4th gray scale can be such as gray value 180, identified local peaking(Gray value 100) More than the 3rd gray scale and less than the 4th gray scale, therefore, the current environment of the image is confirmed as non-backlight environment.
Gray scale at the local peaking for determining gray probability distribution in step S2340 is not more than the 3rd gray scale and not During less than four gray scales, the backlighting detecting can be back to step S110 and resurvey image, or use other backlight Detection method carries out backlight detection.
First gray scale is less than or equal to the 3rd gray scale, and the 3rd gray scale is less than the 4th gray scale, and the 4th gray scale is small In equal to second gray scale.
For first gray scale less than the gray scale at the 3rd gray scale and identified local peaking between described Situation between first gray scale and the 3rd gray scale, can resurvey image and re-start backlight detection, Huo Zheke To carry out backlight detection using other methods.
Similarly, the gray scale at second gray scale and identified local peaking is less than for the 4th gray scale to be situated between Situation between the 4th gray scale and second gray scale, can resurvey image and re-start backlight detection, Or backlight detection can be carried out using other methods.
Fig. 3 shows the specific of second of sample implementation of the step S130 in Fig. 1 according to embodiments of the present invention Flow chart.
Whether in second of sample implementation, it is backlight ring that current environment is determined according to the variance of grey level histogram Border.
For the normalized grey level histogram X=(x1,x2..., x256)T, the population mean μ and variance of intensity profile σ2It can be represented as:
Variance threshold values can be set, when the variance of the grey level histogram extracted is more than the variance threshold values, it is determined that currently Environment is backlight environment, otherwise current environment is non-backlight environment.The variance threshold values can according to experiment, rule of thumb, root Set according to personal like etc..
In step S3310, the variance of extracted grey level histogram is calculated as described above.
Then, in step S3320, determine whether current environment is backlight environment according to the variance calculated.
Fig. 4 shows the specific of the third sample implementation of the step S130 in Fig. 1 according to embodiments of the present invention Flow chart.
In the third sample implementation, backlight degree can be calculated based on variance, and can define backlight degree threshold value, Determine whether current environment is backlight environment based on the relation between the backlight degree and the backlight degree threshold value calculated.
In step S4310, the variance of extracted grey level histogram is calculated as described above.
Then, in step S4320, backlight degree is determined according to the variance calculated.Backlight degree can represent present image Backlight degree.Backlight degree can be the function of the variance or the variance., can be by backlight as an example Spend dBLIt is defined as:
dBL=f(X)=σ
In step S4330, judge whether calculated backlight degree is more than predetermined backlight degree threshold value.
When judging that calculated backlight degree is more than predetermined backlight degree threshold value in step S4330, determined in step S4340 Current environment is backlight environment.
It is true in step S4350 when judging that calculated backlight degree is not more than predetermined backlight degree threshold value in step S4330 Current environment is determined for non-backlight environment.
In order to reduce False Rate, the 4th kind of sample implementation is further provided.
Fig. 5 shows the specific of the 4th kind of sample implementation of the step S130 in Fig. 1 according to embodiments of the present invention Flow chart.
In the 4th kind of sample implementation, backlight degree can be calculated based on variance, and it is true based on the backlight degree calculated Determine backlight ambient probability, then determine whether current environment is backlight environment based on backlight ambient probability again.
Consider to build following sample (dBL, Y), wherein Y only takes positive and negative 1 (± 1), and positive 1 (+1) represents backlight, minus 1 (- 1) table Show non-backlight, dBLFor backlight degree defined above.
Returned by gathering multiple samples, and binary Logistic being using these samples, training obtains Sigmoid forms Probability function:
The Sigmoid form probability functions are represented when backlight degree is dBLWhen, current environment is the probability of backlight environment.By This, can be by backlight degree dBLBe converted to the probability that acquired image I is under backlight environment.It is then possible to pass through the probability Come decision diagram as I whether backlight.
Figure 8 illustrates the transformation curve, wherein transverse axis represents backlight degree dBL, the longitudinal axis represents backlight ambient probability.When When backlight degree is more than some threshold value T, P (Y=1) is more than 0.5, and when backlight degree is less than T, P (Y=1) is less than 0.5.
In step S5310, the variance of extracted grey level histogram is calculated as described above.
In step S5320, backlight degree is determined according to the variance calculated as described above.
Then, in step S5330, according to the backlight degree determine current environment whether be backlight environment probability, i.e. root Backlight ambient probability is determined according to the backlight degree.
Can be such as formula(3)It is shown or as illustrated in fig. 8, backlight ambient probability is determined according to backlight degree.
In step S5340, determine whether current environment is backlight environment according to identified backlight ambient probability.
In one example, backlight ambient probability threshold value is set(For example, 0.7), it is big in identified backlight ambient probability When the backlight ambient probability threshold value, it is backlight environment to determine current environment.Conversely, determining that current environment is non-backlight environment.
In another example, in step S5340, can combine from another backlighting detecting calculated it is inverse Luminous environment probability or other parameters, and the backlight ambient probability calculated based on backlighting detecting according to embodiments of the present invention Final backlight detection is carried out with the testing result from another backlighting detecting, so as to improve accuracy of detection.
Next, backlight detection means 600 according to embodiments of the present invention will be described with reference to Fig. 6.
Figure 6 illustrates the schematic block diagram of backlight detection means 600 according to embodiments of the present invention.
As shown in fig. 6, the backlight detection means 600 include image acquisition component 610, histogram extracting parts 620 and Informating part 630.
The image that image acquisition component 610 is shot under the present circumstances from shooting component retrieval.
Histogram extracting parts 620 extracts the grey level histogram of described image.
Informating part 630 determines whether the current environment is backlight environment according to the grey level histogram.
In the first sample implementation, the informating part 630 is according to gray probability in the grey level histogram point The local peaking of cloth determines whether current environment is backlight environment.
Specifically, the gray scale at the local peaking that the gray probability is distributed is less than the first gray scale or more than the second ash When spending, the informating part 630 determines that current environment is backlight environment;Ash at the local peaking that the gray probability is distributed When degree is more than the 3rd gray scale and is less than four gray scales, the informating part 630 determines that current environment is non-backlight environment, wherein, First gray scale is less than or equal to the 3rd gray scale, and the 3rd gray scale is less than the 4th gray scale, and the 4th gray scale is less than or equal to institute State the second gray scale.
In second of sample implementation, the informating part 630 can include variance calculating unit and environment is determined Part.
Variance calculating unit calculates the variance of the grey level histogram of described image as described above.
Environment determines that part determines whether current environment is backlight environment according to the variance.
Specifically, when the variance of the grey level histogram extracted is more than pre-determined variance threshold value, the environment determines part It is backlight environment to determine current environment.
In the third sample implementation, the informating part 630 can include variance calculating unit and environment is determined Part, and the environment determines that part can further include backlight degree calculating unit and backlight determines part.
Backlight degree calculating unit determines backlight degree according to the variance as described above.It is more than predetermined threshold in the backlight degree During value, the backlight determines that part determines that current environment is backlight environment.
In the 4th kind of sample implementation, the informating part 630 can include variance calculating unit and environment is determined Part, and the environment determine part further can include backlight degree calculating unit, backlight ambient probability calculating unit and Backlight determines part.
Backlight degree calculating unit determines backlight degree according to the variance as described above.
Backlight ambient probability calculating unit determines that current environment is backlight environment according to the backlight degree as described above Probability.
When identified probability is more than predetermined probability threshold value, the backlight determines that part determines that current environment is backlight ring Border.
Alternatively, the backlight determines that part can also be by identified probability and the backlight ring calculated by another method Border probabilistic combination, to determine whether current environment is backlight environment.
As it was previously stated, the image acquired in described image obtaining widget 610 can be coloured image or gray level image.
The backlight detection means can also include image converting member, for the coloured image to be converted into gray-scale map Picture.Moreover, the histogram extracting parts extracts the grey level histogram of the gray level image.
The backlight detection means can be applied in the various electronic equipments with digital camera, and can be with list Only processor is realized to realize, or by the corresponding program of central processing unit operation of corresponding electronic equipment.
Although backlighting detecting according to embodiments of the present invention is illustrated by taking normalized grey level histogram as an example above And device, it should be understood, however, that backlighting detecting according to embodiments of the present invention and device can equally be applied in a similar manner Embody the grey level histogram of the relation between each gray scale and pixel count corresponding to each gray scale.
Backlighting detecting and device according to embodiments of the present invention can letter based on the image shot under the present circumstances Backlight detection singly is carried out, the need for eliminating to special CMOS backlight detection sensor, is manufactured into so as to advantageously reduce This.
Backlighting detecting and device according to embodiments of the present invention is described by reference to accompanying drawing above.Art technology Personnel in the case of the spirit without departing from the present invention it will be appreciated that the invention is not restricted to embodiment described above, can make Various modifications, the modification should be also included within the scope of the present invention.The scope of the present invention should by appended claims and its Equivalent is limited.

Claims (17)

1. a kind of backlighting detecting, including:
Gather an image;
Extract the grey level histogram of described image;And
Determine whether current environment is backlight environment according to the grey level histogram
Wherein, determine whether current environment is that backlight environment includes according to the grey level histogram:According to the grey level histogram The local peaking of middle gray probability distribution determines whether current environment is backlight environment, wherein, in gray probability distribution Local peaking at gray scale be less than the first gray scale or during more than the second gray scale, it is backlight environment to determine current environment;And When gray scale at the local peaking that the gray probability is distributed is more than the 3rd gray scale and is less than four gray scales, current environment is determined For non-backlight environment, wherein, first gray scale is less than or equal to the 3rd gray scale, and the 3rd gray scale is less than the 4th gray scale, described 4th gray scale is less than or equal to second gray scale,
Wherein, the gray scale at the local peaking that the gray probability is distributed between first gray scale and the 3rd gray scale it Between when, or the gray probability be distributed local peaking at gray scale between the 4th gray scale and second gray scale When, resurvey image and re-start backlight detection.
2. backlighting detecting as claimed in claim 1, wherein, according to the grey level histogram determine current environment whether be Backlight environment includes:
Calculate the variance of the grey level histogram of described image;And
Determine whether current environment is backlight environment according to the variance.
3. backlighting detecting as claimed in claim 1, wherein, the image is coloured image, and the gray scale for extracting the image is straight Square figure includes:
Convert the image to gray level image;And
Extract the grey level histogram of the gray level image.
4. backlighting detecting as claimed in claim 1, wherein, the grey level histogram includes multiple gray scales and each ash The corresponding pixel quantity of degree, or
The grey level histogram be normalized grey level histogram, the normalized grey level histogram include multiple gray scales and Probability of occurrence corresponding to each gray scale.
5. backlighting detecting as claimed in claim 2, wherein, determine whether current environment is backlight ring according to the variance Border includes:
Backlight degree is determined according to the variance;And
When the backlight degree is more than predetermined threshold, it is backlight environment to determine current environment.
6. backlighting detecting as claimed in claim 5, wherein,
The backlight degree is the variance, or is the function of the variance.
7. backlighting detecting as claimed in claim 2, wherein, determine whether current environment is backlight ring according to the variance Border includes:
Backlight degree is determined according to the variance;And
The probability that current environment is backlight environment is determined according to the backlight degree.
8. backlighting detecting as claimed in claim 7, wherein, determine whether current environment is backlight ring according to the variance Border also includes:
When identified probability is more than predetermined probability threshold value, it is backlight environment to determine current environment.
9. backlighting detecting as claimed in claim 7, wherein, methods described also includes:
The probability is combined with the backlight ambient probability calculated by another method, to determine whether current environment is backlight ring Border.
10. a kind of backlight detection means, including:
Image acquisition component, for obtaining image, the image is the image shot under the present circumstances;
Histogram extracting parts, the grey level histogram for extracting described image;And
Informating part, for determining whether the current environment is backlight environment according to the grey level histogram
Wherein, the informating part determines current environment according to the local peaking of gray probability distribution in the grey level histogram Whether it is backlight environment, wherein, the gray scale at the local peaking that the gray probability is distributed is less than the first gray scale or is more than During the second gray scale, the informating part determines that current environment is backlight environment;And the local peaks being distributed in the gray probability When gray scale at value is more than the 3rd gray scale and is less than four gray scales, the informating part determines that current environment is non-backlight environment, Wherein, first gray scale be less than or equal to the 3rd gray scale, the 3rd gray scale be less than the 4th gray scale, the 4th gray scale be less than etc. In second gray scale,
Wherein, the gray scale at the local peaking that the gray probability is distributed between first gray scale and the 3rd gray scale it Between when, or the gray probability be distributed local peaking at gray scale between the 4th gray scale and second gray scale When, described image obtaining widget resurveys image, and the informating part re-starts backlight detection.
11. backlight detection means as claimed in claim 10, wherein, the informating part includes:
Variance calculating unit, the variance of the grey level histogram for calculating described image;And
Environment determines part, for determining whether current environment is backlight environment according to the variance.
12. backlight detection means as claimed in claim 10, wherein, described image is coloured image,
The backlight detection means also includes:Image converting member, for the coloured image to be converted into gray level image,
Wherein, the histogram extracting parts extracts the grey level histogram of the gray level image.
13. backlight detection means as claimed in claim 10, wherein, the grey level histogram includes multiple gray scales and each Pixel quantity corresponding to gray scale, or
The grey level histogram be normalized grey level histogram, the normalized grey level histogram include multiple gray scales and Probability of occurrence corresponding to each gray scale.
14. backlight detection means as claimed in claim 11, wherein, the environment determines that part includes:
Backlight degree calculating unit, for determining backlight degree according to the variance,
Backlight determines part, for determining that current environment is backlight environment when the backlight degree is more than predetermined threshold.
15. backlight detection means as claimed in claim 11, wherein, the environment determines that part includes:
Backlight degree calculating unit, for determining backlight degree according to the variance;And
Backlight ambient probability calculating unit, for determining probability of the current environment for backlight environment according to the backlight degree.
16. backlight detection means as claimed in claim 15, wherein, the environment determines that part also includes:
Backlight determines part, for determining that current environment is backlight environment when identified probability is more than predetermined probability threshold value.
17. backlight detection means as claimed in claim 15, wherein, the environment determines that part also includes:
Backlight determines part, for identified probability to be combined with the backlight ambient probability calculated by another method, with true Whether determine current environment is backlight environment.
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