JP2005347811A - White balance correction apparatus and white balance correction method, program and electronic camera apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white balance correction apparatus or the like capable of applying excellent white balance correction to an imaged image or the like in a way of not causing color deviation over the entire region of the image or the like. <P>SOLUTION: An image 101 is divided into a plurality of coefficient blocks 111, R, G, B values of each pixel are individually integrated by each coefficient block 111, and a correction coefficient with respect to a center pixel 112 of each coefficient block 111 is calculated on the basis of the result above. Correction coefficients of a plurality of non-center pixels 122 except the center pixel 121 are individually calculated from the correction coefficients of a plurality of the center pixels 121 existing around the non-center pixels 122 through linear interpolation on the basis of the distance (x, 1-x, y, 1-y) with respect to each center pixel 121. The white balance of each pixel is adjusted by multiplying the correction coefficient acquired by each pixel with all pixels comprising the center pixels 121 and the non-center pixels 122. Even when emission areas of different kinds of light sources exist in the image, the white balance suitable for the entire region of the image can be ensured without causing color deviation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a white balance correction device, a white balance correction method, a program, and an electronic camera device suitable for use in, for example, a digital camera.

  Conventionally, in white balance correction for an image captured by a digital camera or the like, a method of setting the same white balance correction amount for the entire screen is generally used. However, if the subject in the screen has multiple light source irradiations and the irradiation areas are separated to some extent, for example, the subject under the fluorescent lamp is locally exposed to the light source of the bulb, or the flash photography is performed under the fluorescent lamp. Sometimes, the main subject is sufficiently exposed to strobe light, but there are two types in the screen, such as when there is an area where the strobe light is far away and the strobe light does not reach, or there is a peripheral part where the amount of strobe light decreases. If there is a separation region that is dominated by light sources of more than that, it is difficult to apply correction suitable for the entire screen.

In order to solve this problem, for example, Patent Document 1 listed below describes a method of performing white balance correction by dividing an input image into a plurality of block areas and setting different white balance correction amounts for each block. Yes.
JP 2002-271638 A

  However, in the method of performing white balance with different correction amounts for each block as described above, a difference in color tone (color shift) inevitably occurs at the boundary between adjacent blocks, resulting in a reduction in image quality. There was a problem.

  The present invention has been made in view of such conventional problems, and a white balance correction apparatus and a white balance correction capable of performing a good white balance correction that does not cause a color shift over the entire area of a captured image or the like. It is an object to provide a method, a program, and an electronic camera device.

  In order to solve the above problem, in the invention of claim 1, a first coefficient acquisition unit that individually acquires white balance correction coefficients of a plurality of target pixels that are separated from each other in an image; The white balance correction coefficient of the non-target pixel in the image located between them is acquired by interpolation from the correction coefficients of the plurality of target pixels existing around the non-target pixel acquired by the first coefficient acquisition unit. Second coefficient acquisition means that performs white balance correction on the target pixel among the pixels of the image based on the correction coefficient acquired by the first coefficient acquisition means, On the other hand, a correction means for performing white balance correction based on the correction coefficient acquired by the second coefficient acquisition means is provided.

  In such a configuration, the white balance is adjusted for each pixel based on the correction coefficient acquired for each pixel, so that the entire area of the image can be obtained even when there are irradiation areas of different types of light sources in the image. White balance correction suitable for In addition, since the correction coefficient of the non-target pixel located between the plurality of target pixels is obtained by interpolation from the correction coefficients of the plurality of target pixels existing around the non-target pixel, the adjacent target pixel and the non-target pixel Alternatively, the correction coefficient for each pixel between adjacent non-target pixels can be changed smoothly. At the same time, it is possible to reduce the amount of data processing required for white balance correction compared to the case of directly acquiring the correction coefficient of the non-target pixel based on the image.

  In the invention of claim 2, the plurality of target pixels are set for each of a plurality of coefficient blocks into which the image is divided, and the first coefficient acquisition unit is configured to set each of the plurality of target pixels. The correction coefficients are acquired individually based on the color components of all the pixels in the same coefficient block.

  According to a third aspect of the present invention, the first coefficient acquisition unit acquires correction coefficients of the plurality of target pixels from an image including pixels having different color information depending on positions in the image. It was supposed to be.

  In such a configuration, it is possible to reduce the amount of data processing handled when acquiring correction coefficients for a plurality of target pixels.

  In the invention of claim 4, the second coefficient acquisition unit acquires the white balance correction coefficient of the non-target pixel in the image by the first coefficient acquisition unit. The pixel is acquired by linear interpolation based on the distance from a plurality of target pixels existing around the pixel.

  In the invention of claim 5, a first step of individually obtaining white balance correction coefficients of a plurality of target pixels spaced apart from each other in the image, and a non-attention located between the plurality of target pixels A second step of acquiring a white balance correction coefficient in a pixel by interpolation from correction coefficients of a plurality of target pixels existing around the non-target pixel acquired in the first step; Performs white balance correction based on the correction coefficient acquired in the first step, and third step performs white balance correction on the non-target pixel based on the correction coefficient acquired in the second step. And a method including

  According to such a method, the white balance is adjusted for each pixel based on the correction coefficient acquired for each pixel, so that even when there are irradiation areas of different types of light sources in the image, White balance correction suitable for the entire area can be performed. In addition, since the correction coefficient of the non-target pixel located between the plurality of target pixels is obtained by interpolation from the correction coefficients of the plurality of target pixels existing around the non-target pixel, the adjacent target pixel and the non-target pixel Alternatively, the correction coefficient for each pixel between adjacent non-target pixels can be changed smoothly. At the same time, it is possible to reduce the amount of data processing required for white balance correction compared to the case of directly acquiring the correction coefficient of the non-target pixel based on the image.

  In the invention of claim 6, a first process for individually acquiring white balance correction coefficients of a plurality of pixels of interest separated from each other in an image in a computer included in an apparatus having an image processing function; A white balance correction coefficient in a non-target pixel located between a plurality of target pixels is acquired by interpolation from a plurality of target pixel correction coefficients existing around the non-target pixel acquired in the first process. The second process and the target pixel are subjected to white balance correction based on the correction coefficient acquired by the first process, and the non-target pixel is corrected by the second process. A program for executing the third process for performing white balance correction based on the coefficient is provided.

  According to the seventh aspect of the present invention, in the electronic camera that records the subject image picked up by the image pickup means on the recording medium as image data, the white balance correction coefficients of a plurality of target pixels spaced apart from each other in the subject image are individually set. A first coefficient acquisition unit that acquires the white balance correction coefficient of the non-target pixel in the subject image located between the plurality of target pixels. A second coefficient acquisition unit that acquires by interpolation from correction coefficients of a plurality of target pixels existing around the pixel, and of the pixels of the subject image, the target pixel is acquired by the first coefficient acquisition unit; The white balance correction is performed based on the corrected correction coefficient, and the correction coefficient acquired by the second coefficient acquisition unit is applied to the non-target pixel. Was that a correcting means for performing white balance correction based on.

  In such a configuration, all the pixels of the subject image picked up by the image pickup means are adjusted in white balance for each pixel based on the correction coefficient acquired for each pixel, thereby irradiating different types of light sources in the subject image. Even when there is an area, white balance correction suitable for the entire area of the subject image can be performed. In addition, since the correction coefficient of the non-target pixel located between the plurality of target pixels is obtained by interpolation from the correction coefficients of the plurality of target pixels existing around the non-target pixel, the adjacent target pixel and the non-target pixel Alternatively, the correction coefficient for each pixel between adjacent non-target pixels can be changed smoothly. At the same time, it is possible to reduce the amount of data processing required for white balance correction compared to the case of directly acquiring the correction coefficient of the non-target pixel based on the subject image.

  As described above, in the white balance correction apparatus and the white balance correction method of the present invention, it is possible to perform white balance correction suitable for the entire area of the image even when there are irradiation areas of different types of light sources in the image. . In addition, the correction coefficient for each pixel between the adjacent target pixel and the non-target pixel or between the adjacent non-target pixels can be changed smoothly. Therefore, it is possible to perform good white balance correction that does not cause a color shift over the entire area of the captured image or the like. At the same time, the amount of data processing required for white balance correction can be reduced compared to the case where the correction coefficient of the non-target pixel is directly acquired based on the image, so that white balance correction can be performed at high speed.

  In particular, in the invention of claim 3, it is possible to reduce the amount of data processing to be handled when acquiring correction coefficients for a plurality of target pixels. Therefore, in the configuration in which all the processes required for acquiring the correction coefficients for a plurality of pixels of interest are performed by program processing, the correction coefficients for the plurality of pixels of interest can be acquired efficiently.

  Also, according to the electronic camera device of the present invention, it is possible to perform a good white balance correction that does not cause a color shift over the entire area of the captured subject image, and it can be performed at high speed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a block diagram showing a schematic configuration of a digital camera 1 according to the first embodiment of the present invention.

  The digital camera 1 captures a subject with a CCD 2 that is an image sensor, displays a subject image acquired by the imaging on an LCD (liquid crystal display device) 4, and converts the captured subject image into image data according to a photographing operation. In addition to being configured to convert and record in the image memory 5, it has functions of AE (automatic exposure control), AF (autofocus), and AWB (auto white balance). The image memory 5 is a non-volatile memory such as a flash memory that is built in or detachable from the camera body.

  The CCD 2 is provided with a Bayer array primary color filter in the photosensitive portion, and the analog imaging signal output from the CCD 2 is subjected to various signal processing in the signal processing portion 3 and finally a luminance signal. YUV data including (Y signal) and color difference signals (Cb signal, Cr signal), that is, output as a digital image signal.

  The image signal output from the signal processing unit 3 is sent to the LCD 4 and displayed as a subject image when in the shooting standby state. At the time of shooting operation, the CPU 6 compresses the image according to a predetermined format such as JPEG and records it in the image memory 5. The compressed image data recorded in the image memory 5 is read out by the CPU 6 as needed, and once decompressed, it is reproduced and displayed on the LCD 4 as a still image or a moving image.

  The digital camera 1 also includes a ROM 7 in which various control programs necessary for the CPU 6 to compress and expand the image data and control the entire apparatus, a RAM 8 that is a working memory of the CPU 6, and a key input unit 9. The lens driving unit 10 is provided. The ROM 7 stores a program for causing the CPU 6 to function as first coefficient acquisition means and second coefficient acquisition means of the present invention by causing the CPU 6 to perform white balance correction coefficient acquisition processing, which will be described later. .

  The key input unit 9 includes a shutter key and a mode switching key used for switching the operation mode, and outputs an operation signal corresponding to the key operation to the CPU 6. The lens driving unit 10 includes a motor for driving an optical system including a focus lens disposed in front of the CCD 2 in the optical axis direction, a driver for controlling the motor, and the like. Based on this, the lens position is changed.

  FIG. 2 is a block diagram showing details of the signal processing unit 3 described above. The signal processing unit 3 includes an analog processing unit 11 to which an analog imaging signal output from the CCD 2 is input, a black level adjustment unit 12, a color interpolation unit 13, a measurement unit 14, a white balance adjustment unit 15, a gamma correction unit 19, The filter processing unit 20 and the YUV conversion processing unit 21 are included.

  The analog processing unit 11 includes a correlated double sampling circuit (CDS circuit) that reduces drive noise of the CCD 2 included in the imaging signal output from the CCD 2, and an automatic gain control circuit (AGC) that adjusts the gain of the signal after noise reduction. Circuit) and an A / D converter that converts the gain-adjusted signal into a digital signal, and converts an analog imaging signal input from the CCD 2 into a digital image signal, that is, Bayer data. The black level adjustment unit 12 clamps the digitized image signal to a predetermined black level.

  The color interpolation unit 13 performs color interpolation on the R, G, and B color components from the Bayer data input from the black level adjustment unit 12, and generates R, G, and B color component data for each pixel. As shown in FIG. 3A, the measurement unit 14, with respect to Bayer data (hereinafter referred to as a Bayer image) 101 for one screen input from the black level adjustment unit 12, makes one screen 16 × 16 horizontally. Using the divided 256 coefficient blocks 111 as a unit, the R, G, B values of the Bayer data are individually integrated for each coefficient block 111, and the result is output to the CPU 6.

  The white balance adjustment unit 15 is a correction unit of the present invention, and reads out the RGB data on the memory 16 storing the RGB data generated by the color interpolation unit 13 and the white balance correction coefficient (hereinafter referred to as “white balance correction coefficient”) for each pixel. , Simply referred to as a correction coefficient), and a gain multiplication circuit 17 that outputs to the gamma correction unit 19 and a coefficient register 18 in which the correction coefficient is set. The correction coefficients set in the coefficient register 18 are an R pixel gain (R gain coefficient) and a B pixel gain (B gain coefficient) for each pixel sent from the CPU 6 by processing to be described later.

  The gamma correction unit 19 corrects gamma characteristics (gradation characteristics) for the RGB data after white balance adjustment, and the filter processing unit 20 performs various filter processes on the RGB data after gamma correction, and a YUV conversion processing unit. 21 generates YUV data composed of luminance signals (Y) and color difference signals (U, V) from the RGB data for each pixel, and outputs them to the CPU 6 and the LCD 4.

  Next, a procedure related to the white balance correction coefficient acquisition process performed by the CPU 6 while the CCD 2 is driven in the above configuration will be described with reference to the flowchart of FIG.

  The CPU 6 calculates R and B gain coefficients for each coefficient block 111 based on the RGB integration results for each coefficient block 111 in the Bayer image 101 (FIG. 3A) input from the measurement unit 14 (step SA1). The calculated R and B gain coefficients (Rgain, Bgai) are set in the coefficient register 18 of the white balance adjustment unit 15 as the correction coefficient of the center pixel (target pixel) 121 of each coefficient block 111 (step SA2). Subsequently, R and B gain coefficients of non-center pixels (non-target pixels) other than the center pixel are calculated by linear interpolation based on the R and B gain coefficients of a plurality of center pixels 121 around the pixel (step SA3).

For example, as shown in FIG. 3B, the R and B gain coefficients of the non-center pixel 122 are R4 and B4, the R gain coefficients of the four center pixels 121 of the peripheral coefficient block 111 are R0 to R3, and the B gain coefficient. Are R0 and B3, and the distance from the center pixel 121 at the upper left of the non-center pixel 122 is x, y (however, the distance between each center pixel 121 is normalized to 1) by the following formula: Find the coefficient.
R4 = (1-x) (1-y) R0 + x (1-y) R1 + (1-x) yR2 + xyR3
B4 = (1-x) (1-y) B0 + x (1-y) B1 + (1-x) yB2 + xyB3

  The other non-center pixels 122 in the coefficient block 111 located on the outermost periphery in the image are based on the distance from the R and B gain coefficients of the center pixel 121 of the block adjacent to the center pixel 121 of the own block. Calculate by interpolation.

  Then, the calculated R and B gain coefficients of all the non-center pixels 122 are set in the coefficient register 18 of the white balance adjustment unit 15 (step SA4). In step SA3, the non-center pixel 122 that cannot be interpolated, that is, the center pixel 121 in each coefficient block 111 located at the four corners of the Bayer image 101, the corner of the Bayer image 101, and the vertical and horizontal of the Bayer image 101 are displayed. The same R and B gain coefficients as those of the central pixel 121 are set for the non-central pixel 122 in the square area having the vertex of the total of two points constituting the side.

  As a result, the R and B gain coefficients for all the pixels in the image are set in the coefficient register 18 of the white balance adjustment unit 15, and the white balance adjustment unit 15 sets them by the gain multiplication circuit 17 as described above. White balance adjustment is performed by applying the obtained R and B gain coefficients to each pixel.

  As described above, in the present embodiment, since white balance adjustment is performed for each pixel based on the correction coefficient (R, B gain coefficient) acquired for each pixel, there is a plurality of light source irradiations on the subject in the screen, Even when the irradiation areas are separated to some extent, it is possible to ensure a white balance suitable for each irradiation area. At the same time, the correction coefficient of the center pixel 121 of each coefficient block 111 is acquired based on the RGB integration result for each coefficient block 111, and the correction coefficient of the non-center pixel 122 is obtained from the R and B gain coefficients of the plurality of surrounding center pixels 121. Since it is acquired by interpolation, the R and B gain coefficients for each pixel between the boundary portions between adjacent coefficient blocks 111 and between adjacent central pixels 121 and non-central pixels 122 or between adjacent non-central pixels 122 are smooth. Therefore, no color shift occurs at the boundary portion. Therefore, very good white balance correction can be performed on the entire screen.

  In addition, since the correction coefficients of the non-center pixels 122 are acquired by interpolation from the R and B gain coefficients of the plurality of center pixels 121, for example, as compared with the case where the correction coefficients of all the pixels are directly acquired from the Bayer image 101 or the like. Since the amount of data processing required for white balance correction is small, white balance correction can be performed at high speed even if white balance adjustment is performed for each pixel. Further, the processing load on the CPU 6 can be suppressed.

  In the present embodiment, the R and B gain coefficients of the central pixel 121 in each coefficient block 111 are acquired based on the integration values for R, G, and B of the pixels constituting the Bayer image 101 before color interpolation. However, it may be obtained on the basis of the integral value for each color component of R, G, B in each pixel after color interpolation. However, the amount acquired at the stage of the Bayer image 101 reduces the data processing amount when acquiring the integral values for each of R, G, and B for each coefficient block 111 (1/3).

  Further, unlike the present embodiment, the CPU 6 performs all the processes required for acquiring the R and B gain coefficients of the center pixel 121 including the integration process of the R, G, and B values for each coefficient block 111 of the measurement unit 14. In the case of performing the program processing, it is possible to efficiently obtain correction coefficients for a plurality of target pixels. That is, the data processing burden on the CPU 6 can be minimized.

  Further, in the present embodiment, the acquisition of the R and B gain coefficients of the center pixel 121 is shown for each coefficient block 111 obtained by equally dividing the Bayer image 101 into 256, but the number of divisions of the coefficient block 111, Each shape of the coefficient block 111 can be changed as appropriate.

  In addition, although the correction coefficient of the non-center pixel 122 has been described as being obtained by linear interpolation based on the distance from the plurality of center pixels 121 existing around the non-center pixel 122, the correction coefficient of the non-center pixel 122 is calculated by other interpolation methods. For example, another interpolation method such as spline interpolation may be used.

  Further, in the present embodiment, the CPU 6 that integrates the R, G, B values for each coefficient block 111 of the Bayer image 101 in the measurement unit 14 and controls the entire digital camera 1 based on the integration result. Has described the configuration for acquiring the R and B gain coefficients of the center pixel 121. For example, an ASIC (Application Specific Integrated Circuit) that collectively performs various processes including white balance correction on the image signal output from the CCD 2 In the configuration including the above, the above-described functions and the like of the measurement unit 14 and the CPU 6 may be realized by an ASIC.

  In this embodiment, the case where the present invention is adopted in a digital camera equipped with a CCD has been described. However, the present invention is not limited to this, and the present invention is not limited to a digital camera equipped with a CMOS sensor, a CCD, a CMOS sensor, The present invention can also be employed in other imaging devices including an imaging device, for example, various electronic camera devices such as a digital video camera, a mobile phone with a camera, a PDA with a camera, and a personal computer with a camera. Even in that case, the above-described effects can be obtained.

(Embodiment 2)
FIG. 5 is a block diagram showing a personal computer (hereinafter, personal computer) 51 according to the second embodiment of the present invention.

  The personal computer 51 includes a CPU 52 and a display circuit 57 for generating a display signal to be sent to a display device 56 such as a ROM 53, a RAM 54, a built-in clock 55, and a CRT or LCD connected to the CPU 52. In the CPU 52, a slot in which a mouse 59 and a keyboard 60 as input means via an interface 58, a hard disk 61, a CD-ROM drive 62, and various memory cards can be detachably mounted directly or via a predetermined adapter. A built-in or external card drive 63 is connected. The hard disk 61 causes the CPU 52 to execute various white balance correction processes, which will be described later, according to various OSs that are indispensable for the operation of the personal computer 51, and the second coefficient, Various application programs such as an image processing program including a program for functioning as an acquisition unit and a correction unit are installed.

  Next, in the personal computer 51 having the above-described configuration, the content of the white balance correction processing for the image that the CPU 52 executes as necessary when the image processing program is activated will be described with reference to the flowchart of FIG. Here, the image to be processed is taken by an arbitrary digital camera provided with an image sensor having a primary color filter with a Bayer array in the photosensitive portion, like the CCD 2 of the digital camera described in the first embodiment. It is assumed that the captured image is recorded and read from the card drive 63 to the hard disk 61 via, for example, a memory card. Further, it is assumed that the data of the captured image is raw output data of the image sensor generally called RAW data, that is, data for each pixel in the image sensor (here, Bayer data).

  In the following, the CPU 52 reads the image data, that is, Bayer data from the hard disk 61 (step SB1), and then divides one screen into 16 × 16 coefficient blocks 111 (see FIG. 3A). The R, G, and B values are individually integrated every time (step SB2). Then, based on each RGB integration result for each coefficient block, R and B gain coefficients are calculated for each coefficient block (step SB3), and the result is stored in the RAM 54 or the like as a correction coefficient for the center pixel 121 in each coefficient block. (Step SB4). Next, the R and B gain coefficients of the non-center pixels 122 (see FIG. 3B) excluding the center pixel 121 in one screen are determined based on the distance from the plurality of center pixels 121 around each of the plurality of center pixels 121. The R and B gain coefficients of the center pixel 121 are calculated for each pixel by linear interpolation, and the result is stored in the RAM 54 or the like (step SB5). Note that the specific calculation method of the R and B gain coefficients of the non-center pixel 122 by this linear interpolation is the same as that in the first embodiment, and thus the description thereof is omitted.

  Subsequently, color interpolation processing is performed on the image data to be processed to generate RGB data for each pixel (step SB6), and the generated R and B data for each pixel are stored in advance in steps SB3 and SB5. By applying the R and B gain coefficients for each pixel, the white balance is adjusted for each pixel (step SB7). Thereafter, a color image composed of pixel data (RGB data for each pixel) after white balance adjustment is stored in the hard disk 61 in a predetermined image format such as JPEG (step SB8).

  Therefore, also in the personal computer 51 of the present embodiment, as in the digital camera 1 shown in the first embodiment, the subject in the screen has a plurality of light source irradiations, and the irradiation areas are separated to some extent. Even in this case, it is possible to ensure a white balance suitable for each irradiation area. At the same time, color shift does not occur at the boundary between adjacent coefficient blocks 111. Therefore, very good white balance correction can be performed on the entire screen. In addition, even if white balance adjustment is performed for each pixel, white balance correction can be performed at high speed, and the processing burden on the CPU 52 can be suppressed.

  In addition, since the R and B gain coefficients of the center pixel 121 in each coefficient block 111 are acquired based on the integral values for R, G, and B of the pixels that constitute the Bayer image 101 before color interpolation, The correction coefficient can be acquired efficiently. That is, the data processing burden on the CPU 52 can be minimized.

  In the present embodiment, the case where the captured image data to be processed is RAW data has been described. However, the present invention is effective even when image data other than RAW data is targeted. The processing target may be an image recorded in another data format such as JPEG format. For example, when an image in JPEG format is targeted, the recorded image is once expanded into Y, Cb, Cr data for each pixel, further converted into RGB data for each pixel, The R and B gain coefficients of the center pixel 121 in each coefficient block 111 may be acquired based on the integration values for the R, G, and B color components in the pixel. Further, in that case, the R and B gain coefficients of the central pixel 121 in each coefficient block 111 may be acquired based on Cb and Cr data for each pixel.

  Also in the present embodiment, the number of divisions of the coefficient block 111 and the individual shapes of the coefficient block 111 can be changed as appropriate, and the correction coefficient of the non-center pixel 122 can be changed to a plurality of correction coefficients existing around it. Alternatively, the correction coefficient of the center pixel 121 may be obtained using another interpolation method such as spline interpolation other than linear interpolation.

  In the present embodiment, the white balance correction apparatus according to the present invention is realized by installing a predetermined image processing program in the personal computer 51 having a general-purpose configuration as described above. In addition, the present invention may be applied to various types of printers that print an image recorded as image data by a digital camera or the like as long as it has an image processing function, particularly an image processing function for a captured image. Can do. Even in that case, the above-described effects can be obtained.

1 is a block diagram of a digital camera showing a first embodiment of the present invention. It is a block diagram which shows the detail of the signal processing part of the digital camera. It is explanatory drawing which shows the coefficient block in a Bayer image, a center pixel, and a non-center pixel. It is a flowchart which shows the content of the correction coefficient acquisition process of the white balance by CPU. It is a block diagram of the personal computer which shows the 2nd Embodiment of this invention. It is a flowchart which shows the content of the white balance correction process by CPU.

Explanation of symbols

1 Digital camera 2 CCD
3 Signal Processing Unit 5 Image Memory 6 CPU
7 ROM
8 RAM
13 color interpolation unit 14 measurement unit 15 white balance adjustment unit 16 memory 17 gain multiplication circuit 18 coefficient register 51 personal computer 52 CPU
53 ROM
54 RAM
56 display device 61 hard disk 63 card drive 101 Bayer image 111 coefficient block 121 central pixel 122 non-central pixel

Claims (7)

First coefficient acquisition means for individually acquiring white balance correction coefficients of a plurality of target pixels spaced apart from each other in an image;
The white balance correction coefficient of the non-target pixel in the image located between the plurality of target pixels is acquired by the first coefficient acquisition unit, and the plurality of target pixels existing around the non-target pixel is acquired. Second coefficient acquisition means for acquiring the correction coefficient by interpolation;
Of each pixel of the image, the target pixel is subjected to white balance correction based on the correction coefficient acquired by the first coefficient acquisition means, and the second coefficient is acquired for the non-target pixel. A white balance correction apparatus comprising: correction means for performing white balance correction based on a correction coefficient acquired by the means.   The plurality of pixels of interest are set for each of a plurality of coefficient blocks into which the image has been divided, and the first coefficient acquisition unit calculates the correction coefficients of the plurality of pixels of interest for all pixels in the same coefficient block. The white balance correction device according to claim 1, wherein the white balance correction device is acquired individually based on the color components of the white balance.   The first coefficient acquisition unit acquires the correction coefficients of the plurality of pixels of interest from an image composed of pixels having different color information depending on a position in the image. White balance correction device.   The second coefficient acquisition unit calculates a white balance correction coefficient of a non-target pixel in the image from a plurality of target pixels existing around the non-target pixel acquired by the first coefficient acquisition unit. The white balance correction apparatus according to claim 1, wherein the white balance correction apparatus is obtained by linear interpolation based on a distance. A first step of individually acquiring white balance correction coefficients of a plurality of target pixels spaced apart from each other in an image;
A white balance correction coefficient for a non-target pixel located between the plurality of target pixels is acquired by interpolation from a plurality of target pixel correction coefficients existing in the periphery of the non-target pixel acquired in the first step. A second step;
White balance correction is performed on the target pixel based on the correction coefficient acquired in the first step, and white balance correction is performed on the non-target pixel based on the correction coefficient acquired in the second step. And a third step of applying white balance. A computer having a device having an image processing function
A first process of individually acquiring white balance correction coefficients of a plurality of target pixels spaced apart from each other in an image;
A white balance correction coefficient for a non-target pixel located between the plurality of target pixels is acquired by interpolation from a plurality of target pixel correction coefficients existing around the non-target pixel acquired in the first process. A second process to
White balance correction is performed on the target pixel based on the correction coefficient acquired by the first process, and white balance correction is performed on the non-target pixel based on the correction coefficient acquired by the second process. A program for executing the third process. In an electronic camera that records a subject image imaged by an imaging means on a recording medium as image data,
First coefficient acquisition means for individually acquiring white balance correction coefficients of a plurality of target pixels spaced apart from each other in a subject image;
The correction coefficient of the white balance of the non-target pixel in the subject image located between the plurality of target pixels is obtained by calculating the white balance correction coefficient of the plurality of target pixels existing around the non-target pixel acquired by the first coefficient acquisition unit. Second coefficient acquisition means for acquiring the correction coefficient by interpolation;
Of each pixel of the subject image, white balance correction is performed on the target pixel based on the correction coefficient acquired by the first coefficient acquisition unit, and the second coefficient is acquired for the non-target pixel. An electronic camera apparatus comprising: a correction unit that performs white balance correction based on the correction coefficient acquired by the unit.

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