KR20070052018A - Method and apparatus for adjusting white balance in a digital image device - Google Patents

Abstract

The present invention provides a method and apparatus for adjusting white balance of a digital imaging apparatus.

According to the present invention, when the digital imaging apparatus photographs a subject to generate an original image in an image sensor, designates an area in focus, and transmits the image area to the image processor, the image processing unit acquires pixel values of the area in focus on the original image. Detect and calculate an average value of the pixel values.

The image processor calculates difference values between the pixel values of the focused area and the average value, and adds each component value of the color correction value calculated by adding the difference values and pixel values of the focused area to the color correction value. The normalized value is determined for each component by dividing the maximum component value among the components, and the corrected image obtained by obtaining the product of the original image and the normalized value is output.

By doing so, the present invention has the advantage of automatically correcting the white balance of the original image by the image processor to implement the original color of the original image.

 White Balance, Digital Imaging, Focused Area, Pixels, Normalization

Description

Method and Apparatus for Adjusting White Balance in Digital Imaging Device

1 is a flowchart of processing a digital image according to the prior art.

2 is a flowchart of processing a digital image according to an embodiment of the present invention.

3 is a block diagram of a digital imaging apparatus to which the present invention is applied.

The present invention relates to a digital imaging apparatus, and in particular, to a method and apparatus for adjusting white balance of the digital imaging apparatus.

White balance refers to the relative intensity of red, green, and blue in the light source. The light seen by the human eye is always seen as white, which is thought to consist of one color, but in reality, several visible rays are combined.

Every object has its own color mixed with the color of the light source that illuminates it.

But a person can only see the color of the object.

For example, the human eye perceives the same green leaves as almost the same green color in the morning, midday, or sunset, and does not feel unnatural about the color of the leaves, but the CCD (Charge Coupled Device) of the digital imaging device Under the influence of the light or the room, the color that appears strongly with time differs slightly, and the color of the object itself and the color of the light source are mixed and expressed as it is.

Therefore, even when shooting the same subject, the apparent appearance of the captured image varies depending on various light source conditions such as under outdoor sunlight, cloudy days, indoor white lamps, and under fluorescent lights.

This color difference may be corrected by adjusting the white balance of the digital image.

Adjusting the white balance adjusts the brightness of red, green, and blue so that the brightest part of the image taken by the digital imaging device is expressed in white. When using this control function, the light source is separated from the standard RGB balance for daylight. Can be corrected. This is literally 'white balance', that is, white is adjusted to make it look white, which can be said to be a task that the digital imaging apparatus accurately expresses the color of a subject by storing colors felt and accepted by light in the field.

Accordingly, in the conventional digital imaging apparatus, the white balance function is implemented to obtain an average value by detecting pixel values of the entire region, and to determine whether the color component values of the average value are the same and store the same.

In the following Figure 1 will be described in detail the operation according to the embodiment of the prior art.

1 is a flowchart of a white balance process of a digital image according to the prior art.

Referring to FIG. 1, the digital imaging apparatus photographs a subject in operation 110 to generate an original image, and proceeds to operation 120 to determine whether an automatic white balance mode is set. If the manual white balance mode is set, the process proceeds to step 140 where the original image is converted into the set manual white balance value and stored. However, if it is determined as an Auto White Balance (AWB) mode, in step 130, the pixel values of the entire area of the original image are detected. In operation 150, an average value of the entire area pixel values is calculated, and in operation 160, each color component value of the average value is determined to be the same. If the color component values of the average value are not the same, proceed to step 180 to adjust the color component values of each pixel of the original image to be the same, and if the color component values of each pixel are the same, proceed to step 170 Save the image and exit.

In order to express the original color of the subject well in the digital imaging apparatus to which the foregoing description and the above-described prior art are applied, the white balance is manually adjusted in the user's experience or the photograph is taken several times in the case of a beginner. There was an inconvenient problem of having to set the white balance manually.

The present invention devised to solve this problem provides a method and apparatus for adjusting the white balance of an original image affected by a light source in a digital imaging apparatus.

In a preferred embodiment of the present invention, in the method for adjusting the white balance of the digital imaging apparatus,

Photographing the subject to create the original image,

Detecting pixel values of a focused area of the original image;

Using the detected pixel values, calculating normalization values for each color component that emphasizes a main color component of the focused area and reduces other color components;

And outputting a corrected image by multiplying color component values of each pixel of the original image by normalization values of each color component.

The device of the present invention is a digital imaging device for adjusting white balance,

An image sensor unit for photographing a subject and generating an original image;

Detect pixel values of the focused region of the original image, and use the detected pixel values to obtain normalization values for each color component that emphasize the main color components of the focused region and reduce the remaining color components. And an image processor configured to output a corrected image by multiplying the original image.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that those skilled in the art may better understand the detailed description of the invention that follows.

Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. Those skilled in the art should recognize that the disclosed concepts and specific embodiments of the invention may be readily used as a basis for modifying or designing other structures for achieving the same purposes of the present invention. Those skilled in the art should also recognize that structures equivalent to the invention do not depart from the spirit and scope of the broadest form of the invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In addition, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted.

The main subject of the present invention is to correct the original image when the white balance is implemented in the automatic mode in the digital imaging apparatus.

If a pixel value of a specific region of the original image photographed by the digital imaging apparatus is Src_raw, it is expressed as Equation 1 below.

Here, the specific area is a focused area of the original image, which is generally about 3 to 5% of the original image, and may be set manually or automatically.

The pixel value is composed of component values of red, green, and blue.

In addition, the automatic mode white balance is an automatic white balance, that is, Auto White Balance and is abbreviated AWB.

Src_raw = [R_raw G_raw B_raw]

Here, R_raw, G_raw, and B_raw mean red, green, and blue component values generated by the image sensor of the digital imaging apparatus for each pixel of the focused area.

The digital imaging apparatus obtains an average value mean (Src_raw) = [R_mean G_mean B_mean] for each pixel of the focused area, and obtains a difference value by subtracting the average value from each pixel value as shown in Equation 2 below.

Src_raw_temp = Src_raw-mean (Src_raw)

Here, Src_raw_temp is the difference value.

Then, the color correction value is calculated as shown in Equation 3 by adding the difference value to the original pixel value.

Src_raw_final = Src_raw_temp + Src_raw

Where Src_raw_final represents the color correction value.

As such, when the difference value of the pixel calculated by Equation 2 is added to the original pixel value of the focused region, the color having a difference compared to the average color among the original pixel values is further obtained by Equation 3 above. Is emphasized.

For example, in the case of an image which is mainly red, the component value corresponding to red is higher than the average value, so the red value of Src_raw_temp has a positive value, and as a result, the color correction value becomes more red. do.

In contrast, the components corresponding to green and blue are rather reduced, resulting in the entire image being emphasized with a red value.

Max (Src_raw_final) is obtained from the component values of the color correction value Src_raw_final calculated in Equation 3, and this is to obtain a normalization value Var_final, and the normalization value for each component is represented by Equation 4 below. Get>

Var_final (Red) = Src_raw_final (Red) / max (Src_raw_final)

Var_final (Green) = Src_raw_final (Green) / max (Src_raw_final)

Var_final (Blue) = Src_raw_final (Blue) / max (Src_raw_final)

Normalization is to make the maximum value to 1, and in Equation 4, the color correction value of each pixel is divided by the maximum component value among the component values of the color correction value calculated in Equation 3, and the normalization value for each component var_final ( Red), var_final (Green), var_final (Blue). Then, the final color correction value for each component of the original image is obtained as shown in Equation 5 below.

Red_img_result = Red_img_source * var_final (Red)

Green_img_result = Green_img_source * var_final (Green)

Blue_img_result = Blue_img_source * var_final (Blue)

Thus, the final color correction value is obtained by multiplying the normalized values var_final (Red), var_final (Green), and var_final (Blue) obtained by Equation 4 by the pixel values of the original image.

Here, the Red_img_source, Green_img_source, and Blue_img_source are the color component values for each pixel constituting the original image, and the Red_img_result, Green_img_result, and Blue_img_result are the final color correction values calculated in Equation (5).

2 is a flowchart of a white balance process of a digital image according to an exemplary embodiment of the present invention.

2, the operation of the digital imaging apparatus according to the preferred embodiment of the present invention will be described in detail.

Referring to FIG. 2, the digital imaging apparatus generates an original image by photographing a subject in operation 200, and proceeds to operation 210 to set an auto white balance mode. Determine if there is. If the manual white balance mode is set, the process proceeds to step 230 where the original image is converted into the set manual white balance value and stored. However, if it is determined as an auto white balance mode (shown as AWB), in step 220 and 240, pixel values of the focused region of the original image are detected to calculate an average value.

In operation 250, the difference between the pixel values of the focused area and the average value is calculated as in Equation 2.

In operation 260, the color correction values are calculated by adding the difference values and the pixel values of the focused area as shown in Equation 3 below.

In operation 270, the normalization values for each component are determined by dividing the color component values of each of the color correction values by the maximum component value among the color component values of the pixel, as shown in Equation 4.

In operation 280, the pixel values of the original image are multiplied by the normalization values to calculate final color correction values as shown in Equation 5, and outputs a corrected image including the final color correction values.

In operation 290, the corrected image is finally stored in the memory unit or displayed on the display unit.

The detailed structure of the digital imaging apparatus is shown in FIG. 3.

3 is an internal configuration diagram of the digital imaging apparatus having an automatic white balance correction function according to an exemplary embodiment of the present invention. As illustrated, the digital imaging apparatus includes an image processor 320, a color detector 322, an average value calculator 324, a color correction value calculator 326, and an image emphasis unit 328. ), A memory unit 330, and a display unit 340. Herein, operations of the above components will be described based on the white balance correction function.

When the image sensor 310 shown in FIG. 3 photographs a subject to generate an original image, the color detector 322 inside the image processor 320 detects pixel values of a focused area of the original image. . The image sensor unit 310 indicates the focused area, and the image sensor unit 310 transmits information on the focused area of the original image to the color detection unit 322 together with the original image. To pass.

The average value calculator 324 obtains an average value of the detected pixel values, and a color correction value calculator 326 calculates differences between pixel values of the focused area and the average value, and detects the detected pixel values. Color difference values are calculated by adding the difference values. In the image emphasis unit 328, the component normalization value is determined by dividing each component value of the color correction values by the maximum component value among the component values of the color correction value, and multiplying each pixel value of the original image by the component normalization value. A corrected image consisting of the final color correction values is output.

The corrected image is stored in the memory unit 330 or displayed on the display unit 340 by a user's manipulation.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. As an example of the modification, only the example of the digital imaging device has been described, but the present invention can be easily applied to a device including a digital camera, a digital camcorder, and a digital image module, which is a digital imaging device, without significant modification.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

The present invention is characterized in that the white balance is corrected by applying an algorithm for correcting the original color even if the original image is changed by the light source of light when the digital imaging apparatus implements automatic white balance.

As described above, the present invention has an advantage of automatically correcting the white balance of the original image according to the photographing of the subject by the image processor to implement the original color of the original image.

Claims (6)

In the white balance adjustment method of the digital imaging device, Photographing the subject to create the original image, Detecting pixel values of a focused area of the original image; Using the detected pixel values, calculating normalization values for each color component for emphasizing the main color components of the focused region and reducing the remaining color components; And multiplying the color component values of each pixel of the original image by the normalization values of each color component to output a corrected image. The process of claim 1, wherein the normalization values for each color component are calculated. Calculating an average value of pixel values detected in the focused area; Calculating difference values between pixel values of the focused area and the average value; Obtaining color correction values for each pixel by adding the difference values and pixel values of the focused region; And dividing the color component values of each pixel of the color correction values into the maximum component values of the color component values of each pixel to obtain normalization values of the color components. The method of claim 1, further comprising storing the corrected image on a memory unit or displaying the corrected image on a display unit. In the digital imaging device for adjusting the white balance, An image sensor unit for photographing a subject and generating an original image; The pixel values of the focused region of the original image are detected, and normalized values for each color component are used to emphasize the main color components of the focused region and reduce the remaining color components using the detected pixel values. And an image processor for outputting a corrected image by multiplying the normalized values of the color components by the color component values of each pixel of the original image. The method of claim 4, wherein the image processor, A color detector which detects pixel values of a focused area of the original image; An average value calculator for calculating an average of the pixel values; A color correction value calculator configured to calculate difference values between the pixel values of the focused area and the average value of the pixel, and to calculate color correction values for each pixel by adding the difference values and pixel values of the focused area; The color component values of each pixel of the color correction value are divided into the maximum color component values of the pixel component values to determine normalization values for each color component, and the normalization values for each color component are applied to the color component values for each pixel of the original image. Multiplied by And an image emphasis unit for outputting an unknown image. The digital imaging apparatus according to claim 4, further comprising a memory unit for storing the image corrected and output by the image processor or a display unit for displaying on the screen.

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