WO2016184167A1

WO2016184167A1 - Method and device for realizing auto white balance function

Info

Publication number: WO2016184167A1
Application number: PCT/CN2016/072738
Authority: WO
Inventors: 樊灵晶
Original assignee: 中兴通讯股份有限公司
Priority date: 2015-10-16
Filing date: 2016-01-29
Publication date: 2016-11-24
Also published as: CN106604009A

Abstract

Disclosed in this paper is a method for realizing auto white balance function. The method comprises: performing preliminary flashing photography by using a flash whose color temperature is known, so as to obtain a test photograph of an object to be photographed under the environment color temperature determined by the flash, and performing color shift detection on the test photograph, so as to obtain the color shift data of the object to be photographed under the corresponding environment color temperature; estimating the color temperature of the object to be photographed on the basis of the color shift data provided by the test photograph; and according to the estimated color temperature of the object to be photographed, re-photographing the object to be photographed and performing white balance correction on the photographed photograph.

Description

Method and device for realizing automatic white balance function

Technical field

This application relates to, but is not limited to, the field of terminal image processing technology.

Background technique

The human eye and the brain have certain physiological and psychological adaptability to the color temperature, so the color seen is less affected by the color temperature shift, and the camera sensor does not have this ability, so if the photo taken does not pass the white balance If processed, there will be a large deviation from the color seen by the human eye (although the true color of the human eye is also deviated from the white light).

The white balance processing mainly processes the image data obtained by photographing the camera sensor. There are two kinds of data obtained by the camera sensor photographing, RGB format and YUV format. The RGB format describes the color according to the principle of the three-primary color adding system, while the YUV format describes the color according to the principle of brightness (Y) and color difference (U, V). The two data formats can be converted to each other.

The commonly used white balance algorithm is usually based on the assumption of Grey World, which is based on the assumption that the average value of the color of the scene falls within a specific range. If the measured result deviates from the range, the corresponding parameter is adjusted. The correction causes its mean to fall within the specified range.

However, the white balance algorithm is affected by the color temperature. For example, if the camera is in warm tones, using a cool-tone flash can cause the photo to be bluish. If the subject is cold, using a warm-tone flash can cause the photo to turn yellow. For professional recording, you can use the gray board with a light reflectivity of 18% to adjust the exposure parameters, or manually set the ambient color temperature to perform white balance color temperature calibration.

For most non-professional camera users, because they often do not know how to set the white balance parameters (including the ambient color temperature), the automatic white balance function of the mobile phone camera is usually used, but the automatic white balance function is affected by the ambient color temperature. The photos taken in some scenes have the defect of color cast.

Summary of the invention

The following is an overview of the topics detailed in this document. This Summary is not intended to limit the scope of the claims.

This paper provides a method and device for realizing the automatic white balance function, which can adaptively match the ambient color temperature and optimize the automatic white balance function.

An embodiment of the present invention provides a method for implementing an automatic white balance function, where the method includes:

Performing pre-flash shooting with a flash of a known color temperature, obtaining a test photograph of the subject at an ambient color temperature determined by the flash, performing color shift detection on the test photograph, and obtaining a color of the photographed object at a corresponding ambient color temperature. Partial data

Estimating a color temperature of the photographic subject according to color cast data provided by the test photograph;

The subject is re-photographed based on the estimated color temperature of the subject and white balance correction is performed on the photograph taken.

Optionally, the known color temperature flash lamp comprises any one of the following a)-e):

a) an electronic flash;

b) a pair of dual color temperature flashes;

c) an electronic flash and a pair of dual color temperature flashes;

d) a pair of dual color temperature flashes and other color temperature flashes simulated by the dual color temperature flash;

e) an electronic flash, a pair of dual color temperature flashes, and other color temperature flashes that are simulated by the two color temperature flash.

Optionally, the pre-flash shooting is performed by using a flash of a known color temperature to obtain a test photograph of the subject at an ambient color temperature determined by the flash, including:

Performing pre-flash shooting with a flash of a known color temperature, the ambient color temperature determined by the flash being the color temperature of the flash, obtaining a test photograph of the subject at an ambient color temperature determined by the flash; or

Pre-flash shooting is sequentially performed by using flash lamps of different color temperatures, and the ambient color temperature determined by the flash is the color temperature of the flash, and the test photos of the subject at each ambient color temperature are sequentially obtained.

Optionally, performing color shift detection on the test photo to obtain the corresponding target in the ring Color shift data at ambient temperature, including:

Performing color shift detection on the test photograph by using a color circle detection algorithm based on an equivalent circle, and obtaining color shift data of the photographed object at a corresponding ambient color temperature;

The color shift data includes: a red-green color cast coefficient, a yellow-blue color cast coefficient, and a color cast factor for indicating the degree of color shift.

Optionally, the estimating the color temperature of the photographic subject according to the color cast data provided by the test photo comprises:

When the test photo is a sheet, if the color shift data of the test photograph indicates a reddish or yellowish color, it is estimated that the color temperature of the photographed object is higher than an ambient color temperature corresponding to the test photograph; The color shift data indicates a greenish or bluish color, and it is estimated that the color temperature of the subject is lower than the ambient color temperature corresponding to the test photograph; or

When the test photograph is multiple sheets, the test photograph with the lightest color deviation is selected as the first test photograph from the test photograph indicating the reddish or yellowish color shift data, and the green color or bluish color is indicated from the color shift data. The test photograph having the lightest degree of color deviation is selected as the second test photograph, and the color temperature of the photographed object is estimated to be higher than the ambient color temperature corresponding to the first test photograph and lower than the ambient color temperature corresponding to the second test photograph. .

When the test photo is a sheet, compare the color shift data of the test photograph with each record corresponding to the flashing light of the reference photograph in the reference table, and if the exact matching record is found, The ambient temperature corresponding to the found record is taken as the color temperature of the subject. If no exact match is found, a record with the same color shift and the closest color shift is found, and the ambient color temperature corresponding to the found record is taken as the shooting. The color temperature of the object;

Wherein, the reference table includes a color shift data record when each of the known color temperature flashes captures different scenes.

When the test photo is multiple sheets, for each test photo, the color of the test photograph is The partial data is compared with each record corresponding to the flashing light of the reference photo in the reference table. If an exact matching record is found, the ambient color temperature corresponding to the found record is taken as the color temperature of the shooting object, and the end is all The comparison of the test photos; if the exact matching record is not found, the reference color temperature interval is determined according to the interval corresponding to the color cast factor;

If all the test photos do not find an exact match record, the color temperature value of the subject is determined according to the reference color temperature interval determined by each test photo;

Optionally, determining the color temperature value of the photographic subject according to the reference color temperature interval determined according to each test photo includes:

Calculating a partial deviation of the color cast factor sequence {k ₁ , k ₂ , . . . , k _n } of the subject at each flash shooting with each of the flash corresponding to the end point of the interval of each reference color temperature interval The degree of deviation between the color factor sequences {k _ref1 , k _ref2 , . . . , k _refn } is the color temperature of the scene corresponding to the endpoint of the interval of the reference color temperature interval with the lowest degree of deviation; wherein, n It is the number of flashes.

Optionally, the photographing the photographing object according to the estimated color temperature of the photographing object and performing white balance correction on the photograph taken includes:

When re-shooting without using the flash, the estimated color temperature of the subject is used as a white balance parameter, and white balance correction is performed on the photograph taken; or

When re-shooting with the flash, select the flash whose color temperature is closest to the subject for flash shooting, and perform white balance correction on the photograph taken.

Optionally, selecting a flash whose color temperature is closest to the subject is flashing, including:

When the flash of the known color temperature includes a dual color temperature flash, if the estimated color temperature of the subject is within a color temperature range of the dual color temperature flash output, adjusting an input current of the dual color temperature flash to control The dual color temperature flash outputs light of a corresponding color temperature.

An embodiment of the present invention further provides an apparatus for implementing an automatic white balance function, including:

The pre-shooting and color-shift detection module is configured to: perform pre-flash shooting with a flash of a known color temperature, obtain a test photograph of the subject at an ambient color temperature determined by the flash, perform color shift detection on the test photograph, obtain a Depicting color shift data of the subject at a corresponding ambient color temperature;

a color temperature estimation module, configured to: estimate a color temperature of the photographic subject according to color cast data provided by the test photo;

The photographing and white balance correction module is configured to: re-photograph the subject according to the estimated color temperature of the subject and perform white balance correction on the photograph taken.

a) an electronic flash;

b) a pair of dual color temperature flashes;

c) an electronic flash and a pair of dual color temperature flashes;

Optionally, the pre-shooting and color-shift detection module is configured to:

Optionally, the color temperature estimation module is configured to:

When the test photograph is multiple sheets, for each test photograph, compare the color shift data of the test photograph with each record corresponding to the flashing light of the reference photograph in the reference table, such as finding For a perfectly matched record, the ambient color temperature corresponding to the found record is taken as the color temperature of the subject, and the comparison of all the test photos is ended; if the completely matched record is not found, the reference color temperature is determined according to the interval corresponding to the color cast factor. Interval

Optionally, the color temperature estimation module is configured to:

Optionally, the shooting and white balance correction module is configured to:

The embodiment of the present invention further provides a computer readable storage medium storing computer executable instructions for performing the method of any of the above.

Compared with the related art, the method and device for implementing the automatic white balance function provided by the embodiment of the present invention pre-flashes by using a flash with a known color temperature to obtain a test photo of the photographed object, and the test photograph is calculated by the color shift detection algorithm. Color shift data, estimate the ambient color temperature based on the color shift data, and assist the automatic white balance function. Moreover, according to the estimated color temperature, in the application scene requiring flash, the input current of the dual color temperature flash is controlled to perform the photographing by mixing and outputting the appropriate color temperature, thereby optimizing the automatic white balance function.

Other aspects will be apparent upon reading and understanding the drawings and detailed description.

BRIEF abstract

FIG. 1 is a flowchart of a method for implementing an automatic white balance function according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an apparatus for implementing an automatic white balance function according to an embodiment of the present invention.

Embodiments of the invention

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, in the case of no conflict, the features in the embodiments and the embodiments in the present application may be arbitrarily combined with each other.

The embodiment of the invention can construct a brand new flash system, which comprises an electronic flash LED1 (color temperature 5500K) and a pair of dual color temperature flashes, wherein the dual color temperature flash comprises: 1 cold tone flash LED2 (color temperature 7000K) and 1 A warm tone flash LED3 (color temperature 2500K, amber). Each flash of the flash system is controlled by a DC-DC power supply. The input current of the dual color temperature flash LED2 and LED3 is adjustable (for example, adjustable from 100mA to 1.5A), and the input current can be divided into multiple levels. Control, for example, every 200 mA level, can be divided into 8 levels for control. In theory, by controlling the current of the two-color temperature flash lamp, all the color temperatures in the range of 2500K-7000K can be mixed, but the color temperature obtained is relatively rough due to the current control precision and the accuracy of the device itself. The manufacturer's technical manual can refer to how to obtain a corresponding color temperature by adjusting the current. The flash system of the embodiment of the present invention is only responsible for outputting the corresponding current.

Using a camera system based on multiple flash units, the color shift detection algorithm can estimate the color temperature value of the current photographing environment, which is an important hardware aid for the automatic white balance function.

As shown in FIG. 1 , an embodiment of the present invention provides a method for implementing an automatic white balance function, where the method includes:

S101: Perform pre-flash shooting with a flash of a known color temperature, obtain a test photograph of the subject at an ambient color temperature determined by the flash, perform color shift detection on the test photograph, and obtain the photographed object at a corresponding ambient color temperature. Color shift data;

Wherein, the pre-flash shooting is performed by using a flash of a known color temperature, and a test photo of the subject under the ambient color temperature determined by the flash is obtained, including:

Pre-flash shooting with a flash of known color temperature, the ambient color temperature determined by the flash Obtaining a test photograph of the subject at an ambient color temperature determined by the flash for the color temperature of the flash; or

Pre-flash shooting is performed by using flashes of different color temperatures in sequence, and the ambient color temperature determined by the flash is the color temperature of the flash, and the test photos of the subject at each ambient color temperature are sequentially obtained;

Wherein the flash of the known color temperature comprises any one of the following a)-e):

a) an electronic flash;

b) a pair of dual color temperature flashes;

c) an electronic flash and a pair of dual color temperature flashes;

e) an electronic flash, a pair of dual color temperature flashes, and other color temperature flashes simulated by the dual color temperature flash;

The color temperature of the flash lamp used in the flash system constructed in the embodiment of the present invention is 2500K, 5500K, and 7000K, respectively, which is a relatively popular flash lamp on the market.

The color shift detection is performed on the test photo, and the color shift data of the photographed object at a corresponding ambient color temperature is obtained, including:

Among them, the principle of the color circle detection method based on the equivalent circle is that the color cast of the image is not only directly related to the average value of the image chromaticity, but also related to the chromaticity distribution characteristic of the image. If the chromaticity distribution in the two-dimensional histogram on the ab chromaticity coordinate plane is basically a single peak, or the distribution is concentrated, and the chromaticity average is relatively large, there is generally a color shift, and the average value of the chromaticity is Large, the color is more serious. Among them, the a-b chromaticity coordinate plane uses the CIE1976L-a-b chromaticity space standard, and the YUV signal and the a-b chromaticity coordinate can be converted to each other.

On the ab chromaticity plane, the center coordinates of the equivalent circle are {Da, Db}, and the radius is M. The distance from the center of the equivalent circle to the ab chromaticity plane neutral axis dot (0,0) is D. Let L and W be the length and width of the image, the unit is the pixel, a _ij is the a chromaticity data of the pixel of i row j column, and b _ij is the b chromaticity data of the pixel of i row j column. Then the a chrominance component Da of the central coordinate of the equivalent circle is the mean of the chromaticity value of the image a, and the b chrominance component Db of the central coordinate of the equivalent circle is the mean of the chromaticity value of the image b:

M _a is the variance of the image a chromaticity value, and M _b is the variance of the image b chromaticity value:

Among them, the variance reflects the degree of deviation from the center of chromaticity, Ma is the degree of deviation of the a-axis, Mb is the degree of deviation of the b-axis, and the deviation radius M represents the deviation radius from the central coordinate {Da, Db}.

After introducing the concept of the equivalent circle, the ratio of the image average chromaticity D to the chromaticity center distance M, that is, the color cast factor K, is used to measure the degree of color cast of the image.

K=D/M (1-5)

The color cast of the image as a whole can be judged by the position of the equivalent circle on the a-b chromaticity plane. For example, the red and green color cast coefficient is represented by Da, the yellow and blue color cast coefficient is represented by Db, and the color cast factor is represented by K. Da>0, indicating that the image is reddish, Da<0, indicating that the image is greenish; Db>0, indicating that the image is yellowish, and Db<0, indicating that the image is bluish. The larger the value of the color cast factor K, the more severe the image color cast. The calculated values of the red-green color cast coefficient Da, the yellow-blue color cast coefficient Db, and the color cast factor K are used as color shift data.

Wherein, the pre-flash shooting is performed by using a flash of a known color temperature, and a test photo of the subject at an ambient color temperature determined by the flash is obtained, and color shift detection is performed on the test photo, including:

If the number of the flashes of the known color temperature is plural, after the pre-flash shooting is performed by using one flash and the test photos of the subject at the color temperature corresponding to the flash are obtained, color shift detection is performed on the test photo. At the same time, the next flash is used for pre-flash shooting.

The above-described pre-flash shooting and color shift detection by means of a pipeline can improve real-time performance.

S102. Estimating a color temperature of the photographic subject according to the color shift data provided by the test photo.

The estimating the color temperature of the photographic subject according to the color shift data provided by the test photo includes:

When the test photograph is multiple sheets, the test photograph with the lightest color deviation is selected as the first test photograph from the test photograph indicating the reddish or yellowish color shift data, and the green color or bluish color is indicated from the color shift data. The test photograph having the lightest degree of color deviation is selected as the second test photograph, and the color temperature of the photographed object is estimated to be higher than the ambient color temperature corresponding to the first test photograph and lower than the ambient color temperature corresponding to the second test photograph. ;

The color temperature of the subject can be estimated by using the look-up table method, and a reference table including a color shift data record when each of the scenes of the known color temperature captures different scenes is preset. The color shift record includes at least: a red-green color cast coefficient, a yellow-blue color cast coefficient, and a color cast factor for indicating the degree of color shift.

Wherein the color of the subject is estimated according to the color cast data provided by the test photo Warm, including:

The determining, according to the reference color temperature interval determined by each test photo, the color temperature value of the subject, including:

Wherein, the degree of deviation between the two sequences is calculated, and the two sequences can be mapped into the n-dimensional space, and the degree of deviation between the two sequences is determined by calculating the Euclidean distance between the two points in the n-dimensional space. That is, the degree of deviation L between the two sequences corresponding to the above-mentioned color cast factor can be expressed as:

In the pre-flash phase, the color temperatures of the three flashes are 2500K, 5500K, and 7000K, respectively. Different flash pre-shoots obtain three sets of corresponding picture data, and Da, Db, and K values are respectively calculated according to the color-shift detection algorithm. The positive and negative of Da and Db determine which color is biased, and the value of K reflects the degree of color shift. Since three color temperature points are known, the color temperature of the photographed object can be divided into a relatively accurate region according to the values of Da, Db, and K.

For example, if the photo is taken at 2500K, if Da>0, Db>0, and K=1.5, the photo taken is reddish, yellowish, and the color shift is serious, indicating that the color temperature of the object at that time must be greater than 2500K. Look at the photos taken at 5500K. If Da<0, Db<0, K=0.8, then the photo taken. The film is greenish, blue, and the degree of color shift is general, indicating that the color temperature of the object at that time is slightly closer to 5500K.

For the ambient color temperature estimation using the look-up table method, it is necessary to take a picture of each color temperature scene in advance, and calculate the Da, Db, and K values of the three flashes of the known color temperature when shooting different scenes, and obtain a table array (check table method) The basis of the three, indicating the Da, Db, K values of the three reference color temperatures in different color temperature environments. The data obtained from the subsequent comparison table can estimate the current photo color temperature. When the actual calculated value does not exactly match the data in the table, the interval can be determined first, then the degree of deviation between the actual value and the original value in the table can be calculated, and finally the color temperature value with the lowest degree of deviation is selected as the estimated value. Color temperature value.

Since the distinction of color temperature does not need to be very detailed, it is only necessary to distinguish the color temperature of several common scenes, so the number of tables is not many, which can simplify the number of tables and reduce the time for table lookup.

The national standard GB/T 17263-2002 defines the numerical range of color temperature as shown in Table 1:

Table 1

Simulate the above color temperature in the optical laboratory, and take photos with three flashlights. Each camera environment can get a color cast record (including Da, Db, K values) under each flash. Some color cast records form a table for easy table lookup (for example, Table 2, where the data is used for examples does not represent real test values).

Table 2

For example, if a test photograph taken with a 2500K flash, if Da>0, Db>0, and K=1.5, the photograph taken is reddish, yellowish, and the degree of color shift is general, indicating that the color temperature of the object at that time should be greater than 2500K. The table lookup table gives the color temperature range of 2940K-3450K. For the test photos taken with the 5500K flash, if Da<0, Db<0, K=2, the photos taken are greenish, blue, and the color shift is more. According to the table, the color temperature of 2940K is obtained. Therefore, it is finally determined that the current color temperature is 2940K.

If the color shift data of the test photograph does not exactly match the data in the above table, the degree of deviation of the current photograph from the tabular data can be estimated, and the data with a lower degree of deviation is selected for estimating the final color temperature value.

For example, if a test photo taken with a 2500K flash, Da>0, Db>0, K=2, the photo taken is reddish, yellowish, and the color shift is more. According to the table, the table is 3450K-4040K. Color temperature range; test photos taken with 5500K flash, if Da<0, Db<0, K=1.7, it means that the photos taken are greenish, blue, and the color deviation is more. According to the table, the table is also 3450K- 4040K color temperature; test photos taken with 7000K flash, if Da<0, Db<0, K=1.8, then the photo taken is greenish, blue, and the color deviation is more, according to the table lookup table is also 3450K- 4040K color temperature. Then calculate the degree of deviation between the color cast factor sequence of the test photos taken by the three flashes and the standard color cast factor sequence. The actual color cast factor sequence of the test photos taken by the three flash lights is {2, 1.7, 1.8}, three. The standard color cast factor sequence corresponding to the 3450K environment is {1.7, 1.8, 1.9}, and the standard color cast factor sequence corresponding to the 4040K environment is {2.1, 1.5, 1.7}, so the calculation The deviation of the actual color cast factor sequence of the test photograph from the color cast factor sequence corresponding to the 3450K environment in the tabular data is L1, and the actual color cast factor sequence of the test photograph is corresponding to the color cast factor sequence corresponding to the 4040K environment in the tabular data. The degree of deviation is L2;

L2 < L1, so the color temperature of the 4040K shooting environment represented by L2 with a lower degree of deviation is selected as the color temperature of the subject.

The look-up table method mentioned in the embodiment of the present invention is a method for processing the color cast data of the color cast detection algorithm. Other schemes are also feasible if the data is processed by other methods to obtain the estimated color temperature value.

S103: Re-photograph the subject according to the estimated color temperature of the subject, and perform white balance correction on the photograph taken.

The photographing the photographing object and performing white balance correction on the photographed photograph according to the estimated color temperature of the photographed object includes:

When re-shooting with the flash, select the flash with the color temperature closest to the subject The lamp is flashed to perform white balance correction on the captured photo;

Wherein, selecting a flash with the color temperature closest to the subject to perform flash shooting includes:

When the flash of the known color temperature includes a dual color temperature flash, if the estimated color temperature of the subject is within a color temperature range of the dual color temperature flash output, adjusting an input current of the dual color temperature flash to control The two-color temperature flash outputs light of a corresponding color temperature; the photo thus obtained must have no color temperature deviation, so the white balance algorithm can be simplified.

As shown in FIG. 2, an embodiment of the present invention provides an apparatus for implementing an automatic white balance function, including:

The pre-shooting and color-shift detection module 201 is configured to: perform pre-flash shooting with a flash of a known color temperature, obtain a test photo of the subject at an ambient color temperature determined by the flash, and perform color-shift detection on the test photo to obtain Color shift data of the subject at a corresponding ambient color temperature;

The color temperature estimation module 202 is configured to: estimate a color temperature of the photographic subject according to color cast data provided by the test photo;

The photographing and white balance correction module 203 is configured to re-photograph the photographed object based on the estimated color temperature of the photographed subject and perform white balance correction on the photographed photograph.

a) an electronic flash;

b) a pair of dual color temperature flashes;

c) an electronic flash and a pair of dual color temperature flashes;

The pre-shooting and color shift detecting module 201 is configured to:

The color temperature estimation module 202 is configured to:

The shooting and white balance correction module 203 is configured to:

Those of ordinary skill in the art will appreciate that all or a portion of the steps of the above-described embodiments can be implemented using a computer program flow, which can be stored in a computer readable storage medium. The computer program is executed on a corresponding hardware platform (eg, system, device, device, device, etc.), and when executed, includes one or a combination of the steps of the method embodiments.

Alternatively, all or part of the steps of the above embodiments may also be implemented by using an integrated circuit. These steps may be separately fabricated into individual integrated circuit modules, or multiple modules or steps may be fabricated into a single integrated circuit module. achieve.

The devices/function modules/functional units in the above embodiments may be implemented by a general-purpose computing device, which may be centralized on a single computing device or distributed over a network of multiple computing devices.

When the device/function module/functional unit in the above embodiment is implemented in the form of a software function module and sold or used as a stand-alone product, it can be stored in a computer readable storage medium. The above mentioned computer readable storage medium may be a read only memory, a magnetic disk or an optical disk or the like.

Industrial applicability

A method and device for realizing an automatic white balance function provided by an embodiment of the present invention, pre-flashing by a flash with a known color temperature, obtaining a test photograph of a photographed object, and calculating a color shift data of the test photograph by a color shift detection algorithm, according to the color The partial data estimates the ambient color temperature and assists the automatic white balance function. Moreover, according to the estimated color temperature, in the application scene requiring flash, the input current of the dual color temperature flash is controlled to perform the photographing by mixing and outputting the appropriate color temperature, thereby optimizing the automatic white balance function.

Claims

A method of implementing an automatic white balance function, the method comprising:

Performing pre-flash shooting with a flash of a known color temperature, obtaining a test photograph of the subject at an ambient color temperature determined by the flash, performing color shift detection on the test photograph, and obtaining a color of the photographed object at a corresponding ambient color temperature. Partial data

Estimating a color temperature of the photographic subject according to color cast data provided by the test photograph;

The subject is re-photographed based on the estimated color temperature of the subject and white balance correction is performed on the photograph taken.
The method of claim 1 wherein:

The known color temperature flash lamp includes any one of the following a)-e):

a) an electronic flash;

b) a pair of dual color temperature flashes;

c) an electronic flash and a pair of dual color temperature flashes;

d) a pair of dual color temperature flashes and other color temperature flashes simulated by the dual color temperature flash;

e) an electronic flash, a pair of dual color temperature flashes, and other color temperature flashes that are simulated by the two color temperature flash.
The method of claim 2 wherein:

Performing pre-flash shooting with a flash of a known color temperature to obtain a test photograph of the subject at an ambient color temperature determined by the flash, including:

Performing pre-flash shooting with a flash of a known color temperature, the ambient color temperature determined by the flash being the color temperature of the flash, obtaining a test photograph of the subject at an ambient color temperature determined by the flash; or

Pre-flash shooting is sequentially performed by using flash lamps of different color temperatures, and the ambient color temperature determined by the flash is the color temperature of the flash, and the test photos of the subject at each ambient color temperature are sequentially obtained.
The method of claim 3 wherein:

Performing color shift detection on the test photograph to obtain color shift data of the photographed object at a corresponding ambient color temperature, including:

Performing color shift detection on the test photograph by using a color circle detection algorithm based on an equivalent circle, and obtaining color shift data of the photographed object at a corresponding ambient color temperature;

The color shift data includes: a red-green color cast coefficient, a yellow-blue color cast coefficient, and a color cast factor for indicating the degree of color shift.
The method of claim 4 wherein:

The estimating a color temperature of the photographic subject according to the color shift data provided by the test photo includes:

When the test photo is a sheet, if the color shift data of the test photograph indicates a reddish or yellowish color, it is estimated that the color temperature of the photographed object is higher than an ambient color temperature corresponding to the test photograph; The color shift data indicates a greenish or bluish color, and it is estimated that the color temperature of the subject is lower than the ambient color temperature corresponding to the test photograph; or

When the test photograph is multiple sheets, the test photograph with the lightest color deviation is selected as the first test photograph from the test photograph indicating the reddish or yellowish color shift data, and the green color or bluish color is indicated from the color shift data. The test photograph having the lightest degree of color deviation is selected as the second test photograph, and the color temperature of the photographed object is estimated to be higher than the ambient color temperature corresponding to the first test photograph and lower than the ambient color temperature corresponding to the second test photograph. .
The method of claim 4 wherein:

The estimating a color temperature of the photographic subject according to the color shift data provided by the test photo includes:

When the test photo is a sheet, compare the color shift data of the test photograph with each record corresponding to the flashing light of the reference photograph in the reference table, and if the exact matching record is found, The ambient temperature corresponding to the found record is taken as the color temperature of the subject. If no exact match is found, a record with the same color shift and the closest color shift is found, and the ambient color temperature corresponding to the found record is taken as the shooting. The color temperature of the object;

Wherein, the reference table includes a color shift data record when each of the known color temperature flashes captures different scenes.
The method of claim 4 wherein:

The estimating a color temperature of the photographic subject according to the color shift data provided by the test photo includes:

When the test photograph is multiple sheets, for each test photograph, compare the color shift data of the test photograph with each record corresponding to the flashing light of the reference photograph in the reference table, such as finding For a perfectly matched record, the ambient color temperature corresponding to the found record is taken as the color temperature of the subject, and the comparison of all the test photos is ended; if the completely matched record is not found, the reference color temperature is determined according to the interval corresponding to the color cast factor. Interval

If all the test photos do not find an exact match record, the color temperature value of the subject is determined according to the reference color temperature interval determined by each test photo;

Wherein, the reference table includes a color shift data record when each of the known color temperature flashes captures different scenes.
The method of claim 7 wherein:

Determining a color temperature value of the subject according to the reference color temperature interval determined according to each test photo, including:

Calculating a partial deviation of the color cast factor sequence {k 1 , k 2 , . . . , k n } of the subject at each flash shooting with each of the flash corresponding to the end point of the interval of each reference color temperature interval The degree of deviation between the color factor sequences {k ref1 , k ref2 , . . . , k refn } is the color temperature of the scene corresponding to the endpoint of the interval of the reference color temperature interval with the lowest degree of deviation; wherein, n It is the number of flashes.
A method according to any of claims 2-8, wherein:

The photographing the photographing object and performing white balance correction on the photographed photograph according to the estimated color temperature of the photographed object includes:

When re-shooting without using the flash, the estimated color temperature of the subject is used as a white balance parameter, and white balance correction is performed on the photograph taken; or

When re-shooting with the flash, select the flash whose color temperature is closest to the subject for flash shooting, and perform white balance correction on the photograph taken.
The method of claim 9 wherein:

Select the flash with the color temperature closest to the subject for flash shooting, including:

When the flash of the known color temperature includes a dual color temperature flash, if the estimated color temperature of the subject is within a color temperature range of the dual color temperature flash output, adjusting an input current of the dual color temperature flash to control The dual color temperature flash outputs light of a corresponding color temperature.
A device for realizing an automatic white balance function, comprising:

The pre-shooting and color-shift detection module is configured to: perform pre-flash shooting with a flash of a known color temperature, obtain a test photograph of the subject at an ambient color temperature determined by the flash, perform color shift detection on the test photograph, obtain a Depicting color shift data of the subject at a corresponding ambient color temperature;

a color temperature estimation module, configured to: estimate a color temperature of the photographic subject according to color cast data provided by the test photo;

The photographing and white balance correction module is configured to: re-photograph the subject according to the estimated color temperature of the subject and perform white balance correction on the photograph taken.
The apparatus of claim 11 wherein:

The known color temperature flash lamp includes any one of the following a)-e):

a) an electronic flash;

b) a pair of dual color temperature flashes;

c) an electronic flash and a pair of dual color temperature flashes;

d) a pair of dual color temperature flashes and other color temperature flashes simulated by the dual color temperature flash;

e) an electronic flash, a pair of dual color temperature flashes, and other color temperature flashes that are simulated by the two color temperature flash.
The apparatus of claim 12 wherein:

The pre-shooting and color shift detecting module is set to:

Performing pre-flash shooting with a flash of a known color temperature, the ambient color temperature determined by the flash being the color temperature of the flash, obtaining a test photograph of the subject at an ambient color temperature determined by the flash; or

Pre-flash shooting is sequentially performed by using flash lamps of different color temperatures, and the ambient color temperature determined by the flash is the color temperature of the flash, and the test photos of the subject at each ambient color temperature are sequentially obtained.
The apparatus of claim 13 wherein:

The pre-shooting and color shift detecting module is set to:

Performing color shift detection on the test photograph by using a color circle detection algorithm based on an equivalent circle, and obtaining color shift data of the photographed object at a corresponding ambient color temperature;

The color shift data includes: a red-green color cast coefficient, a yellow-blue color cast coefficient, and a color cast factor for indicating the degree of color shift.
A computer readable storage medium storing computer executable instructions for performing the method of any of claims 1-10.