KR101639664B1 - Photographing apparatus and photographing method - Google Patents

Abstract

An image pickup apparatus and an image pickup method capable of reducing the misjudgment of white balance evaluation by shading are provided. The image pickup apparatus and the image pickup method are provided. The current shading coefficient Means for calculating a first RGB block statistical value by dividing a first shading correction completed image generated by shading correction of a sensed image based on the shading correction result into blocks and statistically processing the sensed image; Means for calculating a second RGB block statistic value by dividing the second shading correction completed image generated by the correction into blocks and statistically processing the second shading correction corrected image; means for calculating a current light source estimation value based on the second RGB block statistical value; And means for calculating a white balance gain based on the light source estimation value of the first RGB block and the first RGB block statistical value .

Description

[0002] Photographing apparatus and photographing method [0003]

The present invention relates to an imaging apparatus and an imaging method.

In an electronic imaging device such as a digital still camera, a process of performing white balance correction so that a white subject is whitened regardless of the light source color of the surrounding environment of the subject is added. The white balance correction determines whether or not a light source is based on the RGB block statistical values obtained by dividing the digital image into a plurality of blocks, and calculates the white balance gain. Then, the image quality is corrected by applying the calculated white balance gain to the image. The above digital image is obtained by photoelectrically converting a subject image obtained through an optical system such as a lens into an image pickup device such as a CCD image sensor.

In addition, irrespective of the problem of white balance, in an electronic image pickup apparatus, there is a case where a peripheral light amount is attenuated due to the influence of the characteristics of the lens imaging optical system itself. In fact, the luminance distribution characteristics are different for each of the three primary colors of light. Therefore, the captured image is unnaturally colored due to the difference in the luminance distribution characteristic for each color. This phenomenon is called color shading.

However, when color shading occurs, a problem arises that white balance accuracy is deteriorated because it affects a digital image used for white balance correction.

Therefore, Patent Document 1 discloses a technique for evaluating a center portion of an image without determining an image peripheral portion by using a threshold value to determine an area usable as an evaluation of white balance so that the RGB block statistical value is not influenced by color shading have.

Patent Document 2 discloses a method for judging a light source by performing an evaluation for white balance before shading correction and adaptively changing a shading coefficient according to the type of light source.

Patent Document 1: JP-A-2007-325222

Patent Document 2: Japanese Patent Application Laid-Open No. 2008-85388

However, in Patent Document 1, there are many scenes in which a center of an image is evaluated so as not to be influenced by shading, but a subject of a light source color exists in the periphery of the image. Therefore, in the white balance gain calculation, there is a problem that the light source can not be detected effectively unless the whole image is evaluated, rather than only the center portion of the image is evaluated.

The technique described in Patent Document 2 is a method for dynamically calculating a shading correction coefficient suitable for the photographing environment of the electronic imaging apparatus in consideration of the fact that the color shading is changed under the influence of the photographing environment light of the subject. However, shading correction is not performed at the time of light source determination for white balance gain calculation, and therefore, shading is influenced at the time of light source determination. Therefore, there is a problem that the color evaluation error at the periphery of the image becomes large.

In Patent Document 2, the light source is judged without correcting the shading, and the white balance gain is applied after the shading correction. Therefore, it is necessary to adjust the convergence point in order to calculate the optimum white balance gain, which complicates a series of processes.

However, a method of performing the shading correction at the preceding stage of the light source determination processing for calculating the white balance gain can be considered.

Shading, however, is affected by the optical components of the lens, such as zoom or iris, as well as the ambient light. Therefore, it is preferable to dynamically calculate a shading correction coefficient suitable for the photographing environment for the shading correction. However, if the shading correction coefficient is changed dynamically, the RGB block statistic value, which is an input value for the light source determination, is influenced by the dynamically changing shading correction. Therefore, there arises a problem that correct light source determination can not be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a shading correction method capable of evaluating the entire image without limiting the white balance evaluation area of the image to a part of the image, Which is capable of reducing the misjudgment of the white balance evaluation by the image pickup device and the image pickup method.

According to one aspect of the present invention, there is provided an image processing method for calculating a current shading coefficient for calculating a current shading coefficient on the basis of an immediately preceding light source estimated value calculated based on an image frame immediately before or an image pick- A first shading correction unit that divides the first shading correction finished image into blocks and performs statistical processing on the first shading correction finished image to generate a first shading correction corrected image by performing a shading correction on the sensed image based on the current shading coefficient, A second shading correction section for generating a second shading correction completion image by shading correction of the sensed image based on a predetermined default shading coefficient; A second RGB block statistic unit for calculating a second RGB block statistic value by dividing the first RGB block statistic value into blocks, A white balance gain calculating unit for calculating a white balance gain based on the current light source estimation value and the first RGB block statistical value, and a white balance gain calculating unit for calculating a white balance gain based on the first shading correction completion And a white balance processing unit for applying white balance correction to the image.

With this configuration, the white balance gain is calculated based on the current light source estimation value and the first RGB block statistical value, and the white balance gain is applied to the first shading correction completed image, thereby performing the white balance correction. Here, in order to calculate the current light source estimation value, a second shading correction completed image is generated by performing shading correction on the sensed image based on a predetermined default shading coefficient, the second shading correction completed image is divided into blocks, 2 Calculate the RGB block statistics. And the current light source estimate is calculated based on the second RGB block statistic value. Also, in order to calculate the first RGB block statistic value, first, the current shading coefficient is calculated based on the immediately preceding light source estimated value calculated on the basis of the immediately preceding image frame or the image pick-up setting information at the time of image pick-up, To generate a first shading-corrected image. The first RGB block statistical value is calculated by dividing the first shading-corrected image into blocks and statistically processing the same. The photographing setting information at the time of photographing is, for example, information such as a zoom position, a diaphragm, and a sensitivity.

The second RGB block statistics unit calculates the second RGB block statistics by calculating the difference between the default shading coefficient and the current shading coefficient and multiplying the first RGB block statistics. With this configuration, the second RGB block statistic value can be calculated using the first RGB block statistical value, and the actual statistical processing is sufficient only in the calculation of the first RGB block statistical value.

The default shading coefficient is an average single coefficient calculated based on a shading that changes depending on the light source color. With this configuration, the second shading-corrected image is generated by shading-correcting the captured image by using the default shading coefficient determined as one.

The default shading coefficient is prepared for each shooting setting condition at the time of imaging. With this configuration, the second shading-corrected image is generated by shading-correcting the captured image by using one of several prepared default shading coefficients for each of the imaging setting conditions at the time of imaging. The photographing setting conditions are, for example, conditions for different states of lenses such as diaphragm.

Wherein the color shade calculating unit calculates a block weight for each block by performing a color evaluation of the block based on the white balance design adjustment value adjusted based on the picked light source color data by applying the default shading coefficient and the second RGB block statistical value, And calculates the light source estimation value based on the weight and the second RGB block statistical value. According to this configuration, the white balance design adjustment value is adjusted based on the light source color data captured by applying the default shading coefficient, and the color evaluation of the block is made based on the white balance design adjustment value and the second RGB block statistical value, The block weight is calculated. Then, the light source estimation value is calculated based on the block weight value and the second RGB block statistic value.

The light source estimating unit calculates a light source estimation value by performing weighted averaging based on the color coordinates and block weights calculated based on the second RGB block statistical value. According to this configuration, the color coordinate is calculated based on the second RGB block statistical value, and the light source estimation value is calculated by weighted averaging based on the block weight for each block reflecting the color coordinate and color evaluation result.

The white balance gain calculating section calculates the white balance gain based on the first RGB block statistical value using the block weight value. According to this configuration, the white balance gain is calculated based on the first RGB block statistic value suitable for the current shading correction coefficient using the block weight for each block reflecting the color evaluation result.

The block weight is calculated so as to vary with the luminance of the object calculated from the light source estimation value and the photographing setting information. In this configuration, the photographing setting information is information such as a shutter speed, a diaphragm, and a sensitivity, and the block weight is changed according to the light source estimation value or the subject luminance (e.g., the brightness (BV value) of the ambient light.

According to another aspect of the present invention for solving the above problems, there is provided a method of calculating a shading coefficient, comprising the steps of: calculating a current shading coefficient based on an immediately preceding light source estimated value calculated based on an image frame immediately before or shooting setting information at the time of shooting; Calculating a first RGB block statistic value by dividing the first shading correction completed image into blocks and statistically processing the first shading corrected first image, calculating a first RGB block statistic value by performing a shading correction on the sensed image based on the current shading coefficient, , Generating a second shading-corrected image by shading-correcting the sensed image based on a predetermined default shading coefficient, calculating a second RGB block statistic value by dividing the second shading- Calculating a current light source estimate based on a second RGB block statistical value, The imaging method of claim 1, characterized in that on the basis of the RGB block statistics apply to the phase and complete the first shading correction, the white balance gain image for calculating a white balance gain comprising the step of correcting the white balance is provided.

According to the embodiments of the present invention, it is possible to evaluate the entire image without limiting the white balance evaluation area of the image to a part of the image, and it becomes possible to perform the white balance correction evaluation after the shading correction, thereby reducing the misjudgment of the white balance evaluation by the shading .

1 is a block diagram showing an image processing unit 110 of a digital still camera according to an embodiment of the present invention.
2 is a block diagram showing an image processing unit 110, a shading table calculating unit 120 and a white balance gain calculating unit 130 of a digital still camera according to the present embodiment.
3 is a flowchart showing a schematic operation of the image pickup apparatus according to the embodiment.
4 is a flowchart showing the shading correction operation of the embodiment.
5 is a flowchart showing the white balance gain calculating operation of the embodiment.
6 is an explanatory view showing an embodiment in which shading by the diaphragm and shading by the light source are separated.
7 is a conceptual diagram showing block division of an image area.
8 is a cross-sectional view illustrating a shading occurrence state according to a light source.
9 is a cross-sectional view illustrating a shading occurrence state of each light source.
FIG. 10 is a cross-sectional view illustrating a shading occurrence state for each light source.
11 is a cross-sectional view showing a default shading correction coefficient.
12 is a sectional view showing a current shading correction coefficient applied at the time of photographing.
13 is a cross-sectional view showing conversion coefficients from the current shading correction coefficient to the default shading correction coefficient.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, elements having substantially the same functional configuration in the present specification and drawings are denoted by the same reference numerals, and redundant description will be omitted.

<One embodiment of the present invention>

The digital still camera (image pickup apparatus) according to the embodiment of the present invention includes a shading correction unit 106 for correcting the shading occurring in the captured image, and a white balance processing unit 108 for performing the white balance correction of the captured image . Even when the shading correction coefficient is adaptively changed dynamically based on the light source estimation result or the like, the entire image can be evaluated without being influenced by the change in the shading correction coefficient, and the optimum white balance correction can be performed.

1 is a block diagram showing an image processing unit 110 of a digital still camera according to the present embodiment. 2 is a block diagram showing an image processing unit 110, a shading table calculating unit 120, and a white balance gain calculating unit 130 of a digital still camera according to the present embodiment. Fig. 3 is a flowchart showing a schematic operation of the image pickup apparatus according to the present embodiment.

The image processing unit 110 includes a CCD image sensor or a CMOS image sensor 102, an image preprocessing unit 104, a shading correction unit 106, a white balance processing unit 108, A demosaic processing unit 112, a color compensating unit 114, a gamma processing unit 116, and the like.

First, an RGB image signal (RAW data) is obtained in an analog front end (AFE) including an image pickup element such as the CCD image sensor or the CMOS image sensor 102 in FIG. 1 (step S101). RGB image signals are subjected to image preprocessing such as defective pixel correction and black level correction. Various electronic processing such as shading correction processing, white balance correction processing, Bayer interpolation (demosaicing) processing, color correction processing, and gamma correction processing are performed to record images.

In the present embodiment, shading correction processing is performed before the white balance gain calculating section 130 (steps S102 and S105).

After image preprocessing on the picked-up RGB image signal, shading correction is performed. The shading correction is a process for correcting the phenomenon (shading) in which the amount of ambient light is attenuated due to the influence of the characteristics and the like of the lens imaging optical system itself. In the shading, the degree of occurrence of the shading is changed not only by the influence of the optical characteristic but also by the light source of the surrounding environment of the subject.

FIGS. 8, 9, and 10 are cross-sectional views illustrating shading occurrence states for respective light sources, and illustrate the differences between the shading generation states. FIG. 8 shows a situation of shading under sunlight, FIG. 9 shows a situation of shading under fluorescent lamp, and FIG. 10 shows a situation of shading under incandescent lamp.

These phenomena are called color shading because different shading occurs for each of the RGB three primary colors of light. Then, a correction coefficient according to the image pixel coordinates is set for each of the RGB colors.

The shading table calculator 120 calculates an optimal shading correction coefficient according to camera setting information such as diaphragm and zoom and light source estimation result of white balance processing.

The calculated shading correction coefficients are used in the shading correction unit 106 of the image processing unit 110 shown in Fig. The image data after the shading correction is input to the white balance gain calculating unit 130. [

The block statistical processing unit 132 shown in Fig. 2 divides the already shaded-corrected image into blocks and acquires the statistical values of RGB pixels for each block (step S103). The RGB statistical values are input to the AWB processing unit 136. However, the shading correction coefficient (current shading table) applied to the image is multiplied by the difference between the shading correction coefficient (the default shading table) used by the white balance gain calculation unit 130 and the light source estimation (step S104) .

[SHADING CORRECTION]

Fig. 4 is a flowchart showing the shading correction operation of the present embodiment.

The shading changes with respect to the optical elements of the lens such as zoom, iris, and the shooting environment light source. Therefore, the shading correction coefficient is calculated dynamically as shown in Fig.

The shading correction unit 106 acquires shooting information such as shooting setting conditions such as AV (aperture value), TV (shutter speed), SV (imaging sensitivity), and zoom and a light source estimated value calculated from the immediately preceding frame image S111).

Then, an optimal current shading correction coefficient is calculated based on the acquired image capturing setting information, the light source estimation value, and the shading information previously stored in the shading data storage unit (step S112).

In addition, the factor for changing the shading shown above is an example of various factors. Therefore, the method of calculating the shading correction coefficient is not limited to the example described in this specification. That is, even when the shading correction coefficient is changed dynamically as another factor, it is important to provide a proper white balance as described later.

Next, the current shading correction coefficient calculated in step S112 is applied to the RGB image signal (image data), and the shading correction is performed on the image data (step S113).

The shading-corrected image data is used for the RGB block statistical processing (step S114).

[White balance gain calculation]

5 is a flowchart showing the white balance gain calculating operation of the present embodiment.

(For the first RGB block statistic value)

The white balance gain calculating unit 130 divides the image area of the image data to which the shading correction is applied into N × M blocks as shown in FIG. 7, for example. 7 is a conceptual diagram showing block division of an image area. A plurality of pixels are included in the divided block. The statistical values of the RGB pixels are calculated as the first RGB block statistical values.

(For white balance design adjustment value)

The parameter group (hereinafter, also referred to as &quot; white balance design adjustment value &quot;) for determining the light source determination or the operation following range is used in white balance gain calculation and is stored in advance in the white balance design adjustment value storage unit. The white balance design adjustment value is calculated by the designer of the electronic image pickup device in advance by performing white balance design adjustment processing.

The white balance design adjustment processing uses an electronic imaging device to be incorporated. Then, a gray chart or a color chart is photographed under various light sources to obtain light source color data. In addition, the shading correction coefficient applied at this time is a single representative shading correction coefficient (the default shading correction coefficient).

The designer of the electronic imaging apparatus determines a white balance design adjustment value such as a color evaluation determination threshold value or a white balance tracking range to be used in white balance gain calculation based on the light source color data obtained by the white balance design adjustment processing.

(For color evaluation processing)

As described above, the white balance design adjustment value is optimized for the shading-corrected image data by applying the default shading correction coefficient. Therefore, when the RGB block color evaluation is performed on the captured image, if the first RGB block statistical value obtained by dynamically changing the shading correction coefficient is used, color evaluation can not be performed correctly. Since it is affected by the difference between the current shading correction coefficient and the default shading correction coefficient.

Thus, in the present embodiment, color evaluation processing is performed in consideration of the difference between the current shading correction coefficient and the default shading correction coefficient currently applied.

11 is a cross-sectional view showing a default shading correction coefficient. The color shading can be corrected by setting different coefficients for R, G and B. Since the shading correction coefficient is multiplied by the coefficient in units of pixels, an average multiplication coefficient is obtained as shown in Equation (1), which is defined as Def_RAve, Def_GAve, and Def_BAve.

In Equation (1), h represents the width of the image, v represents the height of the image, and DefRCoeff, DefGCoeff, and DefBCoeff represent the default shading correction coefficients of RGB, respectively.

A shading correction coefficient (current shading correction coefficient) suitable for the photographing setting information or the like is applied. 12 is a sectional view showing a current shading correction coefficient applied at the time of photographing. In the example shown in Fig. 12, a coefficient larger than the default shading coefficient shown in Fig. 11 is applied.

As in the case of the default shading correction coefficient, an average multiplication coefficient is obtained as shown in Equation (2), which is set as Cur_RAve, Cur_GAve, and Cur_BAve. In Equation (2), h represents the width of the image, v represents the height of the image, and CurRCoeff, CurGCoeff, and CurBCoeff represent the respective current shading correction coefficients of RGB.

The white balance design adjustment value is incorporated in the image sensing apparatus so that light source estimation can be correctly performed with the default shading correction coefficient applied. Therefore, when performing the RGB block color evaluation processing, the conversion coefficient from the current shading correction coefficient to the default shading correction coefficient shown in FIG. 13 is used. 13 is a cross-sectional view showing a conversion coefficient from the current shading correction coefficient to the default shading correction coefficient.

Delta_RAve, Delta_GAve, and Delta_BAve are calculated using Equation (3) based on the already calculated average multiplication coefficient of the default shading correction coefficient and the average multiplication coefficient of the current shading correction coefficient.

The shading difference correction section 134 multiplies the calculated conversion coefficients Delta_RAve, Delta_GAve and Delta_BAve by the first RGB block statistic value used when calculating the white balance gain, and outputs the result to the second RGB block statistical values R ', G ', B').

In the light source evaluation, the second RGB block statistical values (R ', G', B ') are used. This makes it possible to perform the light source evaluation equivalent to the case where the default shading correction coefficient used in the white balance design adjustment processing is applied to the image area of the image data to which the shading correction is applied.

Next, the color evaluation processing procedure of the present embodiment will be described.

For example, a color coordinate per block is calculated based on the second RGB block statistical value. The color coordinate at this time may be a coordinate system that is an R / G ratio and a B / G ratio as shown in Equation (4), or a coordinate converted to a standard value of another color.

In the RGB block color evaluation, the evaluation weight coefficient w (RGB block weight) for each block is determined based on the coordinate values, luminance values, and the like of the color coordinates (x, y).

(Light source estimation processing)

The light source estimation coordinates (Cx, Cy) are calculated by weighted averaging the RGB block weight w and the block color coordinates using Equation (5). In Equation (5), Bh and Bv represent a horizontal direction and a vertical direction when an image is divided into a plurality of blocks.

The calculated light source estimation coordinates Cx and Cy are used as light source information for determining a shading correction coefficient when calculating a shading correction coefficient in the next frame image processing.

(White balance gain calculation)

The white balance gains Kr, Kg, and Kb are obtained by weighted averaging as shown in Equation (6) using the first RGB block statistic values (R, G, B) and the RGB block weight w. The RGB block weight w may be changed according to the value of the light source estimation coordinates (Cx, Cy) or the brightness (BV value) of the ambient light.

The above description of the calculation method of the white balance gain is an example of the present invention and does not limit the calculation method of the evaluation weight for each block or the conversion method to the color coordinate.

Thus, the first RGB block statistic value is multiplied by the conversion coefficient from the current shading correction coefficient to the default shading correction coefficient, and the RGB block color evaluation is performed using the second RGB block statistic value obtained as a result. As a result, it is possible to evaluate the light source equivalent to the case where the default shading correction coefficient is applied without being influenced by the current shading correction coefficient.

The white balance gain calculator 130 calculates the white balance gain based on the RGB block weight reflecting the result of the default shading correction coefficient and the first RGB block statistics obtained by applying the shading correction coefficient to the image data.

The calculated white balance gains Kr, Kg and Kb are applied to the image processing section 110 in the white balance processing section 108 as shown in Fig.

The above description has been made on the assumption that the second RGB block statistic value is a single default shading coefficient.

&Lt; Another embodiment of the present invention >

As another embodiment of the present invention, the shading correction coefficient may be stored for each shading generation factor. 6 is an explanatory view showing an embodiment in which shading by diaphragm and shading by a light source are separated.

Fig. 6 is an example of a case in which the diaphragm is in the open state and the state in which the diaphragm is narrowed. As shown in FIG. 6, the default shading correction coefficient is prepared in the default shading table according to the state of the diaphragm, that is, the state for the open state and the state for the state where the default shading correction coefficient is narrowed. The default shading correction coefficient is selected according to the state of the current aperture. Thus, the second RGB block statistical value can be a statistical value corrected for the change due to the iris. In addition, the white balance design adjustment value is prepared for the open state and for the narrowed state.

In the RGB block color evaluation, one of the two default shading correction coefficients and one of the two white balance design adjustment values is selected according to the state of the iris. Next, the second RGB block statistic value is calculated using the selected default shading correction coefficient, and more accurate light source estimation can be performed by using the calculated second RGB block statistical value and the selected white balance design adjustment value.

One of the shading correction difference coefficients prepared in advance for each light source type is selected according to the light source estimation result. Or the shading correction difference coefficient is calculated by interpolation processing or the like based on the shading correction difference coefficient for each light source type. The current shading correction coefficient is obtained by multiplying the already obtained default shading correction coefficient by the selected or calculated shading correction correction coefficient.

Thus, by providing a plurality of default shading correction coefficients, more accurate light source estimation can be performed.

&Lt; Effects of one or other embodiments of the present invention >

(1) evaluating the entire image at the time of white balance gain calculation, (2) suppressing the influence of shading at the time of color evaluation for white balance gain calculation, (3) A method of performing the shading correction at the previous stage of the light source determination processing for calculating the white balance gain can be conceived in order to satisfy the requirement of calculating the white balance gain.

Shading, however, is affected by the optical components of the lens, such as zoom or iris, as well as the ambient light. Therefore, it is preferable to dynamically calculate a shading correction coefficient suitable for the photographing environment for the shading correction. However, if the shading correction coefficient is changed dynamically, the RGB block statistic value, which is an input value for the light source determination, is influenced by the dynamically changing shading correction. Therefore, there arises a problem that correct light source determination can not be performed.

On the other hand, as described in detail above, in this embodiment, by applying the default shading correction coefficient to the input value of the white balance gain calculating unit 130, the influence of the shading can be suppressed and the light source can be estimated from the whole image. Further, even when the shading correction is dynamically applied based on the zoom position, the diaphragm, and the light source estimation result, it is possible to prevent the light source estimation from being influenced by inversely correcting the change of the shading correction coefficient.

Since the white balance gain is calculated from the first RGB block statistic value reflecting the shading correction coefficient applied to the image processing unit 110 of the output image, complicated processing such as adjusting the convergence point of white balance is not required. As a result, the shading correction optimization and the white balance correction optimization can be compatible with each other, thereby providing good image quality.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. .

For example, in the above-described embodiment, the second RGB block statistic value is obtained by multiplying the first RGB block statistical value by the conversion coefficient, but the present invention is not limited to this example. For example, the second RGB block statistical value may be obtained by multiplying the input image data by the default shading coefficient to obtain the RGB block statistical value.

110 image processing section
102 Image Sensor
104 image pre-
106 Shading Correction
108 White Balance Processor
112 demosaicing processing unit
114 color government
116 Gamma processor

Claims (9)

A current shading coefficient calculating unit for calculating a current shading coefficient based on the immediately preceding light source estimated value calculated based on the immediately preceding image frame or photographing setting information at the time of photographing;
A first shading correction unit for shading-correcting the sensed image based on the current shading coefficient to generate a first shading correction completed image;
A first RGB block statistic unit for dividing the first shading-corrected image into blocks and statistically processing the first shading-corrected image to calculate a first RGB block statistic value;
A second shading correction unit for shading-correcting the captured image based on a predetermined default shading coefficient to generate a second shading-corrected image;
A second RGB block statistic unit for dividing the second shading-corrected image into blocks and statistically processing the second shading-corrected image to calculate a second RGB block statistic value;
A light source estimator for calculating a current light source estimate based on the second RGB block statistics;
A white balance gain calculating unit for calculating a white balance gain based on the current light source estimation value and the first RGB block statistical value; And
A white balance processor for applying the white balance gain to the first shading correction completed image to perform white balance correction;
And the image pickup device. The method according to claim 1,
Wherein the second RGB block statistics unit calculates the second RGB block statistic value by calculating a difference between the default shading coefficient and the current shading coefficient and multiplying the first RGB block statistic value. The method according to claim 1,
Wherein the default shading coefficient is an average single coefficient calculated on the basis of a shading varying depending on a light source color. delete delete delete delete delete delete

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