CN105915875B - White balance calibration method and apparatus and its calibration parameter preparation method and device - Google Patents

Abstract

The invention relates to a white balance calibration method and device and a calibration parameter acquisition method and device thereof. The method for obtaining white balance calibration parameters includes the steps of: obtaining the eyeball area in the image to be calibrated; obtaining the RGB ratio of the eyeball area according to the eyeball area; determining whether the eyeball area is gray according to the RGB ratio; if so, determining the RGB ratio as a white balance calibration parameter . The white balance calibration parameter acquisition device includes: an eyeball area acquisition module, used to acquire the eyeball area in the image to be calibrated; an RGB ratio acquisition module, used to obtain the RGB ratio of the eyeball area according to the eyeball area; a gray detection module, used to obtain the RGB ratio of the eyeball area according to the RGB The ratio determines whether the eyeball area is gray; the white balance calibration parameter determination module is used to determine the RGB ratio as the white balance calibration parameter when the eyeball area is gray. The invention can accurately restore the white balance without being affected by ambient light and background.

Description

Method and device for white balance calibration and method and device for obtaining calibration parameters

technical field

The present invention relates to the technical field of white balance, in particular to a white balance calibration parameter acquisition method, a white balance calibration parameter acquisition device, a white balance calibration method and a white balance calibration device.

Background technique

White balance is a very important concept in the field of TV photography, through which a series of problems of color reproduction and tone processing can be solved. The most basic principle of white balance is to restore white things to white. However, after the sensor (sensor) outputs the image, the ISP (Image Signal Processor, image signal processing) does not know which area itself is white, and can only count the R/G (red/green), B/G of the entire image (blue/green), and then use an algorithm to estimate which ones need to be restored to R:G:B=1:1:1. In this way, once there is a mixed light scene or an object with a single color, the white balance will have defects such as inaccurate restoration.

Contents of the invention

Based on this, it is necessary to provide a white balance calibration method and device and a method and device for obtaining calibration parameters thereof, which can accurately restore white balance without being affected by ambient light and background.

In order to achieve the above object, the technical scheme that the present invention takes is as follows:

A method for obtaining white balance calibration parameters, comprising the steps of:

Obtain the eyeball area in the image to be calibrated;

Obtaining the RGB ratio of the eyeball area according to the eyeball area;

Determine whether the eyeball area is gray according to the RGB ratio;

If yes, determine the RGB ratio as a white balance calibration parameter.

A device for obtaining white balance calibration parameters, comprising:

The eyeball area acquisition module is used to acquire the eyeball area in the image to be calibrated;

an RGB ratio obtaining module, configured to obtain the RGB ratio of the eyeball area according to the eyeball area;

A gray detection module, configured to determine whether the eyeball area is gray according to the RGB ratio;

The white balance calibration parameter determination module is configured to determine the RGB ratio as a white balance calibration parameter when the eyeball area is gray.

The method and device for obtaining white balance calibration parameters of the present invention utilizes the principle that the eyeball area of Asians is generally gray, and when the eyeball area is gray, the RGB ratio of the eyeball area is determined as the white balance calibration parameter, so that regardless of the background environment and light environment No matter how it is changed, the white balance can be accurately restored by using the white balance calibration parameters.

A white balance calibration method, comprising steps:

Obtain the eyeball area in the image to be calibrated;

Obtaining the RGB ratio of the eyeball area according to the eyeball area;

Determine whether the eyeball area is gray according to the RGB ratio;

If so, determining the RGB ratio as a white balance calibration parameter;

Perform white balance calibration on the image to be calibrated according to the white balance calibration parameters.

A white balance calibration device, comprising:

The eyeball area acquisition module is used to acquire the eyeball area in the image to be calibrated;

an RGB ratio obtaining module, configured to obtain the RGB ratio of the eyeball area according to the eyeball area;

A gray detection module, configured to determine whether the eyeball area is gray according to the RGB ratio;

A white balance calibration parameter determination module, configured to determine the RGB ratio as a white balance calibration parameter when the eyeball area is gray;

A white balance calibration module, configured to perform white balance calibration on the image to be calibrated according to the white balance calibration parameters.

The white balance calibration method and device of the present invention utilize the principle that the eyeball area of Asians is generally gray. When the eyeball area is gray, the RGB ratio of the eyeball area is determined as the white balance calibration parameter, and then the white balance is performed according to the white balance calibration parameter. Calibration so that the white balance can be accurately restored regardless of changes in the background environment and lighting environment.

Description of drawings

FIG. 1 is a schematic flowchart of an embodiment of a method for obtaining white balance calibration parameters of the present invention;

Fig. 2 is a schematic structural diagram of an embodiment of a device for obtaining white balance calibration parameters of the present invention;

3 is a schematic flowchart of an embodiment of a white balance calibration method of the present invention;

4 is a schematic structural diagram of an embodiment of the white balance calibration device of the present invention;

FIG. 5 is a schematic structural diagram of an embodiment of a white balance calibration module of the present invention.

detailed description

In order to further illustrate the technical means adopted by the present invention and the achieved effects, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and preferred embodiments.

Firstly, the specific implementation of the method and device for obtaining white balance calibration parameters will be introduced in detail.

As shown in Figure 1, a method for obtaining white balance calibration parameters includes steps:

S110. Obtain the eyeball area in the image to be calibrated;

S120. Obtain the RGB ratio of the eyeball area according to the eyeball area;

S130. Determine whether the eyeball area is gray according to the RGB ratio;

S140. If yes, determine the RGB ratio as a white balance calibration parameter.

The method of the present invention can be realized according to a corresponding program, and the program runs in a mobile terminal with a camera function, such as a mobile phone, a smart tablet, a digital camera, and the like. The implementation process of each step is introduced in detail below.

In step S110 and step S120, the camera is turned on, and the eyeball area of the image in the viewfinder screen of the camera is acquired, wherein the identification of the eyeball area can be implemented according to existing methods in the prior art. After obtaining the eyeball area, calculate the RGB ratio of the eyeball area.

In step S130 and step S140, gray means no color, RGB color components are all equal, and white balance calibration uses neutral gray as a reference.

There are many ways to determine whether the eyeball area is gray according to the RGB ratio. For example, in one embodiment, the RGB ratio includes a first ratio (R/G) of R and G and a second ratio of B and G (B /G);

The step of determining whether the eyeball area is gray according to the RGB ratio may include:

If the first ratio is less than a first threshold and the second ratio is less than a second threshold, then determining that the eyeball area is gray;

If the first ratio is greater than or equal to a first threshold, or the second ratio is greater than or equal to a second threshold, it is determined that the eyeball area is not gray.

The first threshold and the second threshold can be set according to actual needs, and they can be different values or the same value. If the R/G or B/G exceeds the corresponding threshold, it indicates that the eyeball area is not gray, and it may be the blue eyeball of a foreigner, or it may be the reason for colored glasses or reflective glasses. The RGB ratio of the eyeball area Not suitable as a white balance calibration parameter. If both R/G and B/G are within the corresponding threshold range, it indicates that the eyeball area is gray, that is, the eyeball is a black and white eyeball, and it can be used as the basis for white balance restoration, that is, the RGB ratio of the eyeball area can be used as White balance calibration parameters.

It should be noted that the user can also set other ratios and corresponding judgment conditions according to needs, such as setting thresholds corresponding to G/B and R/B, which is not limited in the present invention.

After the white balance calibration parameters are obtained, the existing white balance calibration methods in the prior art can be used to perform white balance calibration. Since the present invention uses the RGB ratio of the eyeball area as gray as the white balance calibration parameters, it is not affected by ambient light and background. Therefore, even if there is a scene with mixed light or an object with a single color, the correct white balance can be restored to the image.

Based on the same inventive concept, the present invention also provides a device for obtaining white balance calibration parameters. The specific implementation of the device of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in Figure 2, a device for obtaining white balance calibration parameters includes:

The eyeball area acquisition module 110 is used to acquire the eyeball area in the image to be calibrated;

RGB ratio obtaining module 120, for obtaining the RGB ratio of the eyeball area according to the eyeball area;

A gray detection module 130, configured to determine whether the eyeball area is gray according to the RGB ratio;

The white balance calibration parameter determination module 140 is configured to determine the RGB ratio as a white balance calibration parameter when the eyeball area is gray.

The device of the present invention can be implemented according to a corresponding chip, and the chip is installed in a mobile terminal with a camera function, such as a mobile phone, a smart tablet, a digital camera, and the like. The implementation process of each module is introduced in detail below.

The camera is turned on, and the eyeball area acquisition module 110 acquires the eyeball area of the image in the viewfinder screen of the camera, wherein the identification of the eyeball area can be implemented according to existing methods in the prior art. After the eyeball area is obtained, the RGB ratio obtaining module 120 calculates the RGB ratio of the eyeball area.

There are many ways for the gray detection module 130 to determine whether the eyeball area is gray according to the RGB ratio. For example, in one embodiment, the RGB ratio includes a first ratio (R/G) of R and G and a second ratio of B and G. Ratio (B/G), the gray detection module 130 determines that the eyeball area is gray when the first ratio is less than the first threshold and the second ratio is less than the second threshold; When it is greater than or equal to the first threshold, or the second ratio is greater than or equal to the second threshold, it is determined that the eyeball area is not gray.

The first threshold and the second threshold can be set according to actual needs, and they can be different values or the same value. If R/G or B/G exceeds the corresponding threshold, it indicates that the eyeball area is not gray, and the RGB ratio of the eyeball area is not suitable as a white balance calibration parameter. If both R/G and B/G are within the corresponding threshold range, it indicates that the eyeball area is gray, that is, the eyeball is a black and white eyeball, which can be used as a basis for white balance restoration, and the white balance calibration parameter determination module 140 will set the The RGB ratio of the eyeball area is used as a white balance calibration parameter.

It should be noted that the user can also set other ratios and corresponding judgment conditions as required, such as setting thresholds corresponding to G/B and R/B, etc., which is not limited in the present invention.

After the white balance calibration parameters are obtained, the existing white balance calibration methods in the prior art can be used to perform white balance calibration. Since the present invention uses the RGB ratio of the eyeball area as gray as the white balance calibration parameters, it is not affected by ambient light and background. Therefore, even if there is a scene with mixed light or an object with a single color, the correct white balance can be restored to the image.

The specific implementation of the white balance calibration method and device of the present invention will be described in detail below.

As shown in Figure 3, a white balance calibration method includes steps:

S210. Obtain the eyeball area in the image to be calibrated;

S220. Obtain the RGB ratio of the eyeball area according to the eyeball area;

S230. Determine whether the eyeball area is gray according to the RGB ratio;

S240. If yes, determine the RGB ratio as a white balance calibration parameter;

S250. Perform white balance calibration on the image to be calibrated according to the white balance calibration parameters.

The method of the present invention can be realized according to a corresponding program, and the program runs in a mobile terminal with a camera function, such as a mobile phone, a smart tablet, a digital camera, and the like. The implementation process of each step is introduced in detail below.

In step S210 and step S220, the camera is turned on, and the eyeball area of the image in the viewfinder screen of the camera is acquired, wherein the identification of the eyeball area can be implemented according to existing methods in the prior art. After obtaining the eyeball area, calculate the RGB ratio of the eyeball area.

In step S230 and step S240, there are many ways to determine whether the eyeball area is gray according to the RGB ratio. For example, in one embodiment, the RGB ratio includes the first ratio of R and G (R/G) and B and the second ratio of G (B/G);

The step of determining whether the eyeball area is gray according to the RGB ratio may include:

If the first ratio is less than a first threshold and the second ratio is less than a second threshold, then determining that the eyeball area is gray;

If the first ratio is greater than or equal to a first threshold, or the second ratio is greater than or equal to a second threshold, it is determined that the eyeball area is not gray.

The first threshold and the second threshold can be set according to actual needs, and they can be different values or the same value. If the R/G or B/G exceeds the corresponding threshold, it indicates that the eyeball area is not gray, and it may be the blue eyeball of a foreigner, or it may be the reason for colored glasses or reflective glasses. The RGB ratio of the eyeball area Not suitable as a white balance calibration parameter. If both R/G and B/G are within the corresponding threshold range, it indicates that the eyeball area is gray, that is, the eyeball is a black and white eyeball, and it can be used as the basis for white balance restoration, that is, the RGB ratio of the eyeball area can be used as White balance calibration parameters.

It should be noted that the user can also set other ratios and corresponding judgment conditions as required, such as setting thresholds corresponding to G/B and R/B, etc., which is not limited in the present invention.

In step S250, after the white balance calibration parameters are determined, white balance calibration can be performed. In one embodiment, the step of performing white balance calibration on the image to be calibrated according to the white balance calibration parameters may include:

S2501. Obtain a first gain according to the ratio of the first preset coefficient to the first ratio;

S2502. Obtain a second gain according to the ratio of the second preset coefficient to the second ratio;

S2503. Perform white balance calibration on the image to be calibrated according to the first gain and the second gain.

The first preset coefficient and the second preset coefficient are adjustable coefficients, which can be adjusted according to the actual needs of the user. For example, the first preset coefficient is K1, the second preset coefficient is K2, the first ratio is R/G, and the second ratio is B/G, then the white balance RGB gain is: K1*G/R, K2 *G/B, according to the white balance gain, the entire image can be restored to the correct white balance.

Because the present invention uses the RGB ratio of the eyeball area as gray as the white balance calibration parameter, the white balance adjustment is performed according to the white balance calibration parameter, and is not affected by ambient light and background, so even if there is a scene with mixed light or an object with a single color, it will The correct white balance can be restored to the image.

Based on the same inventive concept, the present invention also provides a white balance calibration device, and the specific implementation of the device of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in Figure 4, a white balance calibration device includes:

The eyeball area acquisition module 210 is used to acquire the eyeball area in the image to be calibrated;

RGB ratio obtaining module 220, for obtaining the RGB ratio of the eyeball area according to the eyeball area;

A gray detection module 230, configured to determine whether the eyeball area is gray according to the RGB ratio;

A white balance calibration parameter determination module 240, configured to determine the RGB ratio as a white balance calibration parameter when the eyeball area is gray;

The white balance calibration module 250 is configured to perform white balance calibration on the image to be calibrated according to the white balance calibration parameters.

The device of the present invention can be implemented according to a corresponding chip, and the chip is installed in a mobile terminal with a camera function, such as a mobile phone, a smart tablet, a digital camera, and the like. The implementation process of each module is introduced in detail below.

The camera is turned on, and the eyeball area acquiring module 210 acquires the eyeball area of the image in the camera viewfinder, wherein the identification of the eyeball area can be implemented according to existing methods in the prior art. After the eyeball area is obtained, the RGB ratio obtaining module 220 calculates the RGB ratio of the eyeball area.

There are many ways for the gray detection module 230 to determine whether the eyeball area is gray according to the RGB ratio. For example, in one embodiment, the RGB ratio includes the first ratio (R/G) of R and G and the first ratio of B and G. Two ratios (B/G), the gray detection module 230 determines that the eyeball area is gray when the first ratio is smaller than the first threshold and the second ratio is smaller than the second threshold; When the ratio is greater than or equal to the first threshold, or the second ratio is greater than or equal to the second threshold, it is determined that the eyeball area is not gray.

The first threshold and the second threshold can be set according to actual needs, and they can be different values or the same value. If R/G or B/G exceeds the corresponding threshold, it indicates that the eyeball area is not gray, and the RGB ratio of the eyeball area is not suitable as a white balance calibration parameter. If both R/G and B/G are within the corresponding threshold range, it indicates that the eyeball area is gray, that is, the eyeball is a black and white eyeball, which can be used as a basis for white balance restoration, and the white balance calibration parameter determination module 240 will set the The RGB ratio of the eyeball area is used as a white balance calibration parameter.

It should be noted that the user can also set other ratios and corresponding judgment conditions as required, such as setting thresholds corresponding to G/B and R/B, etc., which is not limited in the present invention.

After the white balance calibration parameters are determined, the white balance calibration module 250 can perform white balance calibration. In one embodiment, as shown in FIG. 5, the white balance calibration module 250 may include:

A first gain obtaining unit 2501, configured to obtain a first gain according to the ratio of the first preset coefficient to the first ratio;

A second gain obtaining unit 2502, configured to obtain a second gain according to the ratio of the second preset coefficient to the second ratio;

A white balance calibration unit 2503, configured to perform white balance calibration on the image to be calibrated according to the first gain and the second gain.

Wherein, the first preset coefficient and the second preset coefficient are adjustable coefficients, which can be adjusted according to the actual needs of the user.

Because the present invention uses the RGB ratio of the eyeball area as gray as the white balance calibration parameter, the white balance adjustment is performed according to the white balance calibration parameter, and is not affected by ambient light and background, so even if there is a scene with mixed light or an object with a single color, it will The correct white balance can be restored to the image.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (6)

1. A method for obtaining white balance calibration parameters, comprising the steps of: Obtain the eyeball area in the image to be calibrated; Obtaining the RGB ratio of the eyeball area according to the eyeball area; Determine whether the eyeball area is gray according to the RGB ratio; If so, determining the RGB ratio as a white balance calibration parameter; Wherein, the RGB ratio includes a first ratio of R and G and a second ratio of B and G; The step of determining whether the eyeball area is gray according to the RGB ratio comprises: If the first ratio is less than a first threshold and the second ratio is less than a second threshold, then determining that the eyeball area is gray; If the first ratio is greater than or equal to a first threshold, or the second ratio is greater than or equal to a second threshold, it is determined that the eyeball area is not gray. 2. A white balance calibration method, characterized in that, comprising steps: Obtain the eyeball area in the image to be calibrated; Obtaining the RGB ratio of the eyeball area according to the eyeball area; Determine whether the eyeball area is gray according to the RGB ratio; If so, determining the RGB ratio as a white balance calibration parameter; performing white balance calibration on the image to be calibrated according to the white balance calibration parameters; Wherein, the RGB ratio includes a first ratio of R and G and a second ratio of B and G; The step of determining whether the eyeball area is gray according to the RGB ratio comprises: If the first ratio is less than a first threshold and the second ratio is less than a second threshold, then determining that the eyeball area is gray; If the first ratio is greater than or equal to a first threshold, or the second ratio is greater than or equal to a second threshold, it is determined that the eyeball area is not gray. 3. The white balance calibration method according to claim 2, wherein the step of performing white balance calibration on the image to be calibrated according to the white balance calibration parameters comprises: obtaining a first gain according to a ratio of a first preset coefficient to the first ratio; obtaining a second gain according to a ratio of a second preset coefficient to the second ratio; Perform white balance calibration on the image to be calibrated according to the first gain and the second gain. 4. A device for obtaining white balance calibration parameters, comprising: The eyeball area acquisition module is used to acquire the eyeball area in the image to be calibrated; an RGB ratio obtaining module, configured to obtain the RGB ratio of the eyeball area according to the eyeball area; A gray detection module, configured to determine whether the eyeball area is gray according to the RGB ratio; A white balance calibration parameter determination module, configured to determine the RGB ratio as a white balance calibration parameter when the eyeball area is gray; Wherein, the RGB ratio includes a first ratio of R and G and a second ratio of B and G; The gray detection module determines that the eyeball area is gray when the first ratio is smaller than the first threshold and the second ratio is smaller than the second threshold; when the first ratio is greater than or equal to the first threshold, or the When the second ratio is greater than or equal to a second threshold, it is determined that the eyeball area is not gray. 5. A white balance calibration device, comprising: The eyeball area acquisition module is used to acquire the eyeball area in the image to be calibrated; an RGB ratio obtaining module, configured to obtain the RGB ratio of the eyeball area according to the eyeball area; A gray detection module, configured to determine whether the eyeball area is gray according to the RGB ratio; A white balance calibration parameter determination module, configured to determine the RGB ratio as a white balance calibration parameter when the eyeball area is gray; a white balance calibration module, configured to perform white balance calibration on the image to be calibrated according to the white balance calibration parameters; Wherein, the RGB ratio includes a first ratio of R and G and a second ratio of B and G; The gray detection module determines that the eyeball area is gray when the first ratio is smaller than the first threshold and the second ratio is smaller than the second threshold; when the first ratio is greater than or equal to the first threshold, or the When the second ratio is greater than or equal to a second threshold, it is determined that the eyeball area is not gray. 6. The white balance calibration device according to claim 5, wherein the white balance calibration module comprises: a first gain obtaining unit, configured to obtain a first gain according to the ratio of the first preset coefficient to the first ratio; a second gain obtaining unit, configured to obtain a second gain according to the ratio of the second preset coefficient to the second ratio; A white balance calibration unit, configured to perform white balance calibration on the image to be calibrated according to the first gain and the second gain.