JP2007251857A - Imaging apparatus and imaging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of easily and highly reliably controlling white balance, and to provide an imaging method. <P>SOLUTION: The "white balance reliability calculation processing" of a sub routine is executed (step S1), and the reliability of the white balance is verified (step S2). When the white balance is not reliable, whether or not a flag for judging whether or not to validate a function to calculate the gain of the white balance considered to the optimum from photographed images is ON is verified (step S3) and the flag is OFF, an alarm is displayed on an LCD monitor and a message indicating whether or not to execute detailed setting is displayed (step S4). When an operator which looks at the display is to execute the detailed setting, the "WB detailed setting mode" of the sub routine is executed (step S6), a JPEG image developed by normal AWB and a JPEG image developed by a WB gain set in the WB detailed setting mode are respectively recorded and processing is ended (step S7). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image pickup apparatus and an image pickup method, and more particularly to an image pickup apparatus and an image pickup method that are devised for controlling white balance during color image pickup.

2. Description of the Related Art Conventionally, in an imaging device such as a video camera, a VTR integrated camera, an electronic still camera, or an imaging device attached to a portable terminal device, white balance adjustment (hereinafter referred to as “AWB”) for obtaining stable color reproduction at the time of color imaging. Function) and an exposure adjustment (AE) function for obtaining an appropriate exposure amount.
In general, the white balance adjustment function is an adjustment operation for equalizing the output levels of the R signal, the G signal, and the B signal as shooting signals in a state where a reference subject whose entire screen is white is shot. However, in normal shooting, the subject is not an all-white reference subject, so if an AWB operation is performed assuming that the subject is all white, the resulting imaging is an apparent subject. It becomes a different and unnatural hue. Therefore, by extracting a part that appears white from the imaging screen (white extraction) and performing white balance adjustment on the extracted white part, R (red), G (green), B ( The output level of each signal (blue) is determined.
White extraction is an important factor that affects the accuracy of white balance adjustment, and a plurality of algorithms have been proposed for this purpose.

The prior arts that have been considered for improving the accuracy of white balance adjustment are listed below.
For example, Patent Document 1 intends to appropriately control the white balance even during imaging with an electronic zoom, and is selected by an imaging unit by an imaging unit and a zoom region selection unit. An image pickup apparatus that performs feature extraction for white balance control based on a zoomed area is disclosed.
In addition, for example, Patent Document 2 discloses an imaging device intended to solve the problem that a skin color photographed under a high color temperature is mistakenly determined as white under a low color temperature, and the human skin is whitened. Is disclosed.
Further, for example, Patent Document 3 discloses an imaging method and apparatus for selecting an image data storage method according to an imaging state. For example, based on the reliability of white balance processing, image data storage is disclosed. It is shown to select a method.

"JP 2004-64676 A" "Japanese Patent Laid-Open No. 2004-312139" "JP 2005-176272 A"

However, in the conventional imaging device described in the background art, when the white (achromatic color) does not exist on the entire screen, the above-described white extraction cannot be performed, so an appropriate white balance is set. There was a problem that it was not possible.
For example, when human skin is present on the entire screen, the human skin is mistakenly recognized as white on the low color temperature side, and the human skin color is whitened. There was a problem that became pale.
In general, AWB is an adjustment operation for equalizing the output levels of the R signal, G signal, and B signal as shooting signals in a state where a reference subject whose entire screen is white is shot. In order to equalize the output levels of the R signal, the G signal, and the B signal, a coefficient that is multiplied for each of the input R signal, the input G signal, and the input B signal is a white balance coefficient. Many inventions have been made to realize a more accurate white balance for a shooting scene, but there is no algorithm for realizing 100% of the white balance desired by the operator for all shooting scenes. In some cases, an artistic effect may be aimed at by setting a white balance that is intentionally shifted by the operator's intention. In such a case, RAW data before image processing such as white balance processing ( There is a technique in which raw data obtained by A / D conversion of a signal output from a CCD is recorded, and RAW data is developed with a personal image processing parameter (including white balance) by a PC or the like.

However, the method of saving RAW data has several problems as described below.
(1) RAW data is larger in size than JPEG data, and therefore requires large capacity storage.
(2) It is necessary to have a means for developing RAW data (in the first place, RAW data is intended to realize detailed image quality settings desired by the operator, and development of RAW data capable of achieving this purpose) It is speculated that there is no camera that supports the function.Basically, development is performed after setting fine image quality parameters according to the operator's request using dedicated development software such as PC application Must be processed).
(3) Advanced knowledge associated with development is required. Therefore, it is a high threshold function for a light user who enjoys casually and an operator who is not familiar with the operation of a PC or the like.
Note that the image pickup apparatus disclosed in Patent Document 1 described above is an invention limited to the zoom function, but the problems (1) and (2) are not solved.

In the imaging apparatus disclosed in Patent Document 2 described above, the operator selects human skin (skin color) on the shooting screen, performs color evaluation within the selected detection frame, and sets the white balance. Therefore, according to the present invention, it is possible to set an appropriate white balance even when white detection cannot be performed (when the reliability of AWB is low), and it is possible to prevent the human skin from becoming pale. In that respect, it is the same as the object of the present invention, but differs in configuration and method from the present invention.
Furthermore, in the imaging method and apparatus disclosed in Patent Document 3 described above, when the reliability of AWB is low, in addition to RAW data, data in a format different from RAW data (for example, JPEG format) is recorded. So that you can choose. In that respect, it is the same as the intention of the present invention, but differs in configuration and method from the present invention.
The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an imaging apparatus and an imaging method that enable simple and reliable white balance control. .

  In order to achieve the above-described object, an imaging device according to a first aspect of the present invention provides an imaging unit that converts an optical image of a subject into an electrical signal, and signal processing that converts the electrical signal into first image data. Means for determining and extracting a specific color portion relating to a change in color temperature of the first image data, outputting at least a first white balance parameter with reference to the extracted data, and an input white balance Data format conversion means for converting the first image data into second image data that can be recorded and displayed based on parameters, and image recording means for storing the second image data in an information recording medium. A white balance for determining reliability of auto white balance control based on the first white balance parameter When the reliability determination means and the white balance reliability determination means determine that the reliability of the auto white balance control based on the first auto white parameter is low, the first white balance parameter is different from the first white balance parameter. White balance setting means for allowing the operator to set the white balance parameter of 2 when it is determined that the reliability of the auto white balance control based on the first auto white parameter is low, at least the second white The second image data based on a balance parameter is recorded on the information recording medium.

The white balance reliability determination unit in the imaging apparatus according to claim 2 refers to a determination and extraction result of a specific color portion related to a color temperature change of the first image data output from the auto white balance unit. Features.
The white balance reliability determination means in the imaging device according to claim 3 detects white pixels of the first image data, and at least when the ratio of the white pixels is equal to or less than a predetermined value, It is determined that the reliability is low.
The imaging apparatus according to claim 4, wherein the white balance reliability determining unit determines that the reliability of the auto white balance is low when the white balance reliability determination unit determines that the auto white balance is low in reliability. A balance reliability warning means is further provided.
According to a fifth aspect of the present invention, the auto white balance reliability warning means includes a warning message display means and / or an alarm sound output means.
The white balance setting means according to claim 6 displays, as an initial screen, the second image data based on the first white balance parameter together with a selection bar for setting white balance. It is characterized by.

  In order to achieve the above-described object, an imaging method according to a seventh aspect of the present invention provides an imaging step for converting an optical image of a subject into an electrical signal, and signal processing for converting the electrical signal into first image data. An auto white balance step for determining and extracting a specific color portion related to a change in color temperature of the first image data, and outputting a first white balance parameter with reference to at least the extracted data, and an input white balance A data format conversion step for converting the first image data into second image data that can be recorded and displayed based on the parameters; and an image recording step for storing the second image data in an information recording medium. And determining reliability of auto white balance control based on the first white balance parameter. When the white balance reliability determination step and the white balance reliability determination step determine that the reliability of the auto white balance control based on the first auto white parameter is low, the first white balance parameter is A white balance setting step for causing the operator to set different second white balance parameters, and when it is determined that the reliability of the auto white balance control based on the first auto white parameters is low, at least the second white balance parameter is set. The second image data based on the white balance parameter is recorded on the information recording medium, and an imaging method is provided.

The white balance reliability determination step in the imaging method according to claim 8 refers to a determination extraction result of a specific color portion related to a color temperature change of the first image data output from the auto white balance step. It is characterized by doing.
The white balance reliability determination step in the imaging method according to claim 9 detects white pixels of the first image data, and at least when the ratio of the white pixels is equal to or less than a predetermined value, It is determined that the reliability of white balance is low.
In the imaging method according to the tenth aspect of the present invention, when the white balance reliability determination step determines that the reliability of the auto white balance is low, the operator is informed that the reliability of the auto white balance is low. An automatic white balance reliability warning step for notifying is further provided.
In the imaging method according to an eleventh aspect, the auto white balance reliability warning step includes a warning message display step and / or an alarm sound output step.
In the imaging method according to claim 12, the white balance setting step includes, as an initial screen, the second image data based on the first white balance parameter, together with a selection bar for setting white balance. It is characterized by displaying.

According to the first aspect of the present invention, an imaging unit that converts an optical image of a subject into an electrical signal, a signal processing unit that converts the electrical signal into first image data, and a color of the first image data Auto white balance means for determining and extracting a specific color portion related to a temperature change and outputting a first white balance parameter with reference to at least the extracted data; and the first image data based on the input white balance parameter In an imaging apparatus having data format conversion means for converting into second image data that can be recorded and displayed, and image recording means for storing the second image data in an information recording medium,
The white balance reliability determination means for determining the reliability of the auto white balance control based on the first white balance parameter, and the auto white balance control based on the first auto white parameter by the white balance reliability determination means. White balance setting means for causing the operator to set a second white balance parameter different from the first white balance parameter when it is determined that the reliability is low;
When it is determined that the reliability of the auto white balance control based on the first auto white parameter is low, the second image data based on at least the second white balance parameter is recorded on the information recording medium. In addition to the image obtained by image processing with the white balance parameter of the auto white balance when the reliability of the auto white balance seems low, the white balance parameter of the auto white balance is different from that of the white balance parameter of the auto white balance. Since the image processed using the balance parameter is also stored, there is an effect that it is possible to provide an imaging apparatus capable of providing a more reliable white balance image.

According to the second aspect of the present invention, the white balance reliability determination unit is configured to refer to the determination and extraction result of the specific color portion related to the color temperature change of the first image data output from the auto white balance unit. Therefore, it is possible to provide an imaging device that can compensate for the problem that the white balance parameter of the auto white balance cannot detect white or the accuracy of the auto white balance is lowered when there are few white portions in the screen. it can.
According to the third aspect of the present invention, the white balance reliability determining means detects the white pixels of the first image data, and at least when the ratio of the white pixels is equal to or less than a predetermined value, the white balance is determined. If the white detection is not possible, or if there are few white parts on the screen, refer to the white detection ratio to reduce the accuracy of auto white balance. It is possible to provide an imaging device that can compensate for the problem.
According to the fourth aspect of the present invention, when the white balance reliability determining means determines that the reliability of the auto white balance is low, the auto white that informs the operator that the reliability of the auto white balance is low. Since the balance reliability warning means is provided, it is possible to warn the operator that the reliability of the auto white balance is low, and the operator who receives this warning, for example, confirms the image and does not like it. Then you can shoot again. In addition, it is possible to provide an imaging apparatus that allows an operator who is familiar with the digital camera to reset the image by referring to the manual.

According to the fifth aspect of the present invention, the auto white balance reliability warning means includes warning message display means and / or alarm sound output means. An imaging device that can effectively warn that the reliability is low can be provided.
According to the invention described in claim 6, the white balance setting means displays the second image data based on the first white balance parameter together with the selection bar for setting the white balance as the initial screen. With this configuration, the operator can provide an imaging apparatus that can set the white balance by operating the selection bar while checking the actual image on the screen.

According to the seventh aspect of the present invention, an imaging step for converting an optical image of a subject into an electrical signal, a signal processing step for converting the electrical signal into first image data, and the first image data An auto white balance step for determining and extracting a specific color portion relating to a change in color temperature of the image and outputting a first white balance parameter with reference to at least the extracted data; and the first image based on the input white balance parameter In an imaging method, comprising: a data format conversion step for converting data into second image data that can be recorded and displayed; and an image recording step for storing the second image data in an information recording medium.
A white balance reliability determination step for determining reliability of auto white balance control based on the first white balance parameter;
When it is determined by the white balance reliability determination step that the reliability of the auto white balance control based on the first auto white parameter is low, a second white balance parameter different from the first white balance parameter is set. A white balance setting step for the operator to set,
When it is determined that the reliability of the auto white balance control based on the first auto white parameter is low, the second image data based on at least the second white balance parameter is recorded on the information recording medium. If the auto white balance is considered unreliable, separate the white balance parameter from the auto white balance parameter separately from the image obtained by image processing with the auto white balance white balance parameter. Since the image processed using the image is also stored, there is an effect that it is possible to provide an imaging method capable of providing a more reliable white balance image.

According to the eighth aspect of the invention, in the white balance reliability determination step, the determination and extraction result of the specific color portion relating to the color temperature change of the first image data output from the auto white balance step is referred to. Therefore, it is possible to provide an imaging method that can compensate for the problem that the white balance cannot be detected with the white balance parameter of the auto white balance or the accuracy of the auto white balance is lowered when there are few white portions in the screen.
According to the ninth aspect of the present invention, in the white balance reliability determination step, white pixels in the first image data are detected, and at least when the ratio of white pixels is equal to or less than a predetermined value, white balance is detected. If white detection is not possible or there are few white areas on the screen, refer to the white detection ratio to compensate for the problem of reduced auto white balance accuracy. An imaging method that can be provided can be provided.

According to the tenth aspect of the present invention, when it is determined in the white balance reliability determination step that the reliability of the auto white balance is low, the operator is informed that the reliability of the auto white balance is low. Since the auto white balance reliability warning step is included, it is possible to warn the operator that the reliability of the auto white balance is low, and the operator who has received this warning checks the image, for example. If you don't like it, you can shoot again. In addition, it is possible to provide an imaging method that allows an operator who is familiar with a digital camera to reset and take a picture again with reference to a manual.
According to the invention as set forth in claim 11, the auto white balance reliability warning step includes a warning message display step and / or a warning sound output step. It is possible to provide an imaging method capable of effectively warning that the reliability of the image is low.

In the imaging apparatus according to the present invention, the RAW data is not recorded, the JPEG data reflecting the normal AWB result determined by the camera is stored, and the white balance obtained by the detailed white balance setting of the operator is stored. Using another parameter (a white balance parameter different from the white balance parameter in normal AWB, hereinafter abbreviated as “WB parameter”), another JPEG image is created, and this JPEG image is also saved. is doing.
As a method for setting the WB parameter different from the white balance parameter in the normal AWB, for example, the operator selects a fixed WB parameter under each light source set in advance in the camera, and uses the selected WB parameter. Another JPEG image is created and saved. By configuring in this way, even an operator who is not familiar with white balance setting can easily realize high-precision white balance. In addition, even an operator who does not want to record RAW data or a simple camera that does not have a RAW output function can set white balance with high accuracy without problems.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of an imaging apparatus and an imaging method of the present invention will be described in detail with reference to the drawings.
FIGS. 1A, 1B, and 1C are external views of the imaging device according to the first embodiment of the present invention. Among these, FIG. 1A is a plan view, and FIG. FIG. 1B is a front view, and FIG. 1C is a rear view.
1A, 1B, and 1C, a release switch (so-called shutter button) SW1, a mode dial SW2, and a sub LCD (liquid crystal display) 1 are disposed on the upper surface portion of the camera body.
A strobe light emitting unit 3, a distance measuring unit 5, and a remote control (remote controller) light receiving unit 6 are provided in the front portion of the camera body. The optical viewfinder 4 has an objective surface located at the front part of the camera body, and the lens barrel unit 7 is also provided with the objective surface facing the front side. The lens barrel unit 7 includes a photographic lens.

On the back of the camera body are a power switch SW13, LCD monitor 10, AF (auto focus) -LED (light emitting diode) 8, strobe LED 9, wide-angle zoom switch SW3, telephoto zoom switch SW4, self-timer / delete switch SW5, menu A switch SW6, an up / strobe switch SW7, a right switch SW8, a display switch SW9, a down / macro switch SW10, a left / image confirmation switch SW11 and an OK switch SW12 are provided. The main part of the optical viewfinder 4 is accommodated in the camera body, but its eyepiece surface is arranged on the back surface part.
A cover 2 for a memory card / battery loading unit is provided on the side surface of the camera body.
Since the general functions and operations of these parts are well known, detailed description thereof will be omitted.
In addition, the appearance of the imaging apparatus according to the present invention is not necessarily limited to the appearance shown in FIGS. 1A, 1B, and 1C, and may have other appearances. Absent.
In this embodiment, the image input device is a digital camera imaging system using a digital still camera imaging module. However, the image input device is not limited to a camera imaging system, and an image input device and an image processing device, such as a hand scanner + PDA. And an image processing system including a display device.

FIG. 2 is a configuration diagram illustrating a main circuit configuration of the imaging apparatus according to the embodiment of the present invention. In FIG. 2, circuit elements that operate the mechanical elements shown in FIG. 1 are denoted by the same reference numerals as those in FIG. 1.
The imaging apparatus according to the present embodiment moves a lens unit 71 that collects an optical image of a subject, a diaphragm unit 72 that focuses a light beam collected by the lens unit 71, and a plurality of lenses (not shown) to move the focus. An optical image that has passed through the lens driver 71 and the diaphragm 72 is input and converted into an analog image signal by the motor driver 75 that adjusts, drives the diaphragm 72, or drives a mechanical shutter (not shown). CCD (Charge Coupled Device) 101. The CCD 101 converts the subject image into an image signal and outputs the image signal to an F / E-IC (front end integrated circuit) 102. The F / E-IC 102 samples an image signal from the CCD 101 to reduce noise, a CDS (Correlated Double Sampling) 1021, an AGC 1022 that adjusts the output gain of the CDS 1021, and an AGC (automatic gain control). An A / D converter 1023 that converts an analog image signal output from the digital image signal 1022 into a digital image signal; a TG (timing generator) 1024 that generates timing and indicates the operation timing of the A / D converter 1023; .

Further, an SDRAM 103 (image recording means) that records a captured image and stores an image-processed image, a signal processing unit 104 that performs image processing according to an input image signal and image parameters, and an operator who operates the apparatus main body Compression is performed by an operation unit 105 having a push button for the release switch SW1 for operating (see FIG. 1), a ROM 106 storing a control program and data for controlling a CPU 1043 described later, and a compression / decompression unit 1045 described later. A memory card 107 for storing the processed image data.
Also provided is an LCD monitor 10 (FIG. 1C and FIG. 2) on which image data is displayed via a display output control unit 1046 described later.
The signal processing unit 104 outputs a synchronization signal to the CCD 101 and stores in the ROM 106 a CCD interface unit 1041 that captures image data in accordance with the synchronization signal, a memory controller 1042 that transmits image data to the SDRAM 103, and the ROM 106. CPU 1043 that controls the entire apparatus based on the control program that has been input, a data format that can display input image data (first image data), and a YUV data format that can record (second image data) And a YUV conversion unit 1044 (data format conversion means) for converting the image data to the image data, and a compression / decompression unit 1045 for compressing the image data processed by the signal processing unit 104 or expanding the image data into original image data.
In addition, the display output control unit 1046 that controls the display output from the signal processing unit 104, the resize processing unit 1047 that changes the image size according to the display and recording size, and the compression / decompression unit 1045 when recording in JPEG. A media I / F (interface) unit 1048 that controls data compression processing and image data writing processing to the memory card 107.

Hereinafter, a basic operation of the imaging apparatus according to the present embodiment will be described.
The subject image received by the CCD 101 via the lens unit 71 and the diaphragm unit 72 of the mirror copper unit 7 is subjected to correlated double sampling by the CDS 1021 to remove image noise, the gain is adjusted by the AGC 1022 at the subsequent stage, and The A / D converter 1023 converts the signal into a digital video signal and inputs it to the signal processing unit 104.
In the signal processing unit 104, the CCD interface unit 1041 outputs a synchronization signal to the CCD 101 and captures image data in accordance with the synchronization signal. In addition, the memory controller 1042 transmits image data to be stored to the SDRAM 103.
The CPU 1043 controls the entire apparatus based on a control program stored in the ROM 106.
The YUV conversion unit 1044 converts the input image data into a displayable and recordable YUV data format under the control of the CPU 1043. The compression / decompression unit 1045 receives the image data processed by the signal processing unit 104 via the memory controller 1042, compresses it or decompresses it to original image data, and then returns it to the memory controller 1042.

Further, the display output control unit 1046 receives the display output from the signal processing unit 104 via the memory controller 1042 and displays it on the LCD monitor 10. The resize processing unit 1047 receives image data via the memory controller 1042 and changes the image size in accordance with the display or recording size. Further, the media I / F unit 1048 receives image data via the memory controller 1042, writes it to the memory card 107, and reads image data from the memory card 107. Further, it controls data compression processing in the compression / decompression unit 1045 when recording in JPEG.
The SDRAM 103 includes a memory for temporarily storing image data and JPEG compressed data, a memory for holding display data, and a RAM used by the CPU 1043.
Hereinafter, operations characteristic of the imaging apparatus according to the present embodiment will be described in more detail in the case of still image shooting.
When the push button for the release switch SW1 is pressed, an AF (automatic focal length adjustment) function operates before shooting. Thereby, for example, hill-climbing AF that finds the maximum contrast value while moving the CCD 101 is performed, and processing for focusing is performed.

Next, the setting of the number of electronic shutters for still image shooting and the setting of an aperture are performed, and exposure for recording is performed. When the exposure is completed, the mechanical shutter is closed, and RAW data for a still image is output by the CCD 101.
This still image RAW data is taken into the SDRAM 103. At this time, if the interlace transfer method is used, RAW data for all CCD data is written into the SDRAM 103 by a plurality of transfers.
Thereafter, all the RAW data is converted into YUV data by the YUV conversion unit 1044 and written back to the SDRAM 103.
In general, the AWB setting value (first white balance parameter) is reflected during YUV conversion in the YUV converter 1044. The set value of AWB is calculated based on the RGB integration result obtained when the RAW data is taken into the signal processing unit 104 via the F / E-IC 102 output from the CCD 101. More specifically, this is achieved by calculating the R pixel and the B pixel for the G pixel and calculating the set value of AWB such that R = G = B. However, the color matches in this process is when a white subject is photographed. In general photographing, the process of extracting white from the photographed image is performed, and the process is performed on the extracted image. Then, a decent AWB can be obtained to some extent.

When recording is performed in a size smaller than the size of the CCD included in the CCD 101, the resize processing unit 1047 reduces the image.
Even when shooting data is displayed on the LCD monitor 10, the image is reduced to a small image size by the resize processing unit 1047, written back to the SDRAM 103, and then sent to the LCD monitor 10 via the display output control unit 1046. The shooting data is displayed.
The YUV image prepared for recording is compressed into JPEG by the compression / decompression unit 1045. The result compressed to JPEG is written back to the SDRAM 103, and after processing such as header addition is performed, the data is stored in the memory card 107.
As described above, the ROM 106 stores a control program for controlling the camera. In the imaging apparatus according to the present embodiment, as this control program, an AWB control program (automatic white balance means: described later) for calculating the optimum white balance gain from the captured image and a calculation process of the AWB control program are performed. AWB reliability determination program (white balance reliability determination means: described later) for determining the reliability of the white balance performed, and the function of the present invention (that is, the function of calculating the optimum white balance gain from the photographed image) ) And a warning display program (auto white balance) that is activated when it is determined that the function of the present invention is effective and the reliability of the white balance calculated by the AWB is low. Reliability warning means) and WB detailed setting program (white balance setting) Means: includes a later-described), the.

FIG. 3 is a flowchart showing an example of an image processing sequence in the imaging apparatus according to the present invention.
The image processing sequence illustrated in FIG. 3 is executed by the CPU 1043.
First, the subroutine “white balance reliability calculation process” (FIG. 5) is executed (step S1).
Next, the result (reliability determination flag) is verified. If the white balance is reliable, the process proceeds to step S8. If the white balance is not reliable, the process proceeds to step S3 (step S2).
Next, it is verified whether or not a flag for determining whether or not to enable a function for calculating a white balance gain that is considered optimal from the photographed image is ON. If the flag is ON, the process proceeds to step S8. If the flag is OFF, the process proceeds to step S4 (step S3).
Next, a warning is displayed on the LCD monitor 10 and a message indicating whether or not to make detailed settings is displayed (step S4).

Next, it is verified whether or not the operator who visually recognizes this display performs detailed setting. If the detailed setting is not performed, the process proceeds to step S8. If the detailed setting is performed, the process proceeds to step S6 (step S5).
Next, the subroutine “WB detailed setting mode” (FIG. 8) is executed (step S6).
Next, the JPEG image developed with the normal AWB and the JPEG image developed with the WB gain set in the WB detailed setting mode are recorded in the SDRAM 103, respectively, and the process ends (step S7).
In step S8, the JPEG image developed with the normal AWB is recorded in the SDRAM 103, and the process ends.
Hereinafter, the operation of the AWB control program will be briefly described.
As described above, the image received by the CCD 101 via the lens unit 71 is AD-converted by the A / D converter 1023 (that is, converted into a digital video signal) and input to the signal processing unit 104. A primary color filter is mounted on the surface of the CCD 101.

FIG. 4 is an explanatory diagram showing a primary color Bayer array as one configuration example of the primary color filter mounted on the surface of the CCD 101.
In general, the primary color filter mounted on the surface of the CCD 101 can be constituted by a primary color Bayer array as shown in FIG. Based on this phenomenon Bayer array configuration, the signal processing unit 104 can divide the input video signal by the number of blocks set vertically and horizontally, and integrate the size of the video signal in each block for each color. it can. For example, when a block is divided into 16 × 16, the sizes of R pixels, B pixels, GR pixels, and GB pixels can be integrated for each of 256 blocks.
In the AWB control program, R gain and B gain represented by the following calculation formulas are calculated for each of the above blocks.

R gain = integrated value of GR pixel / integrated value of R pixel B gain = integrated value of GB pixel / integrated value of B pixel By this calculation, the ratio of the size of R pixel or B pixel to G pixel in each block is calculated. can do. Then, by multiplying the R pixel by the R gain and multiplying the B pixel by the B gain, a signal of R = B = G can be generated.

Further, by calculating the R gain and the B gain from the white (achromatic) portion on the screen, an appropriate white balance can be calculated. The process for this is the white detection process. In the ROM 106, white is photographed in advance under various light sources (from the low color temperature side to the high color temperature side), and values of each R gain and B gain at this time are held. This is called a white detection range, and is set with a width including variations.
Calculate the R gain and B gain of each block for the captured image, determine whether or not this is included in the white detection range, and calculate the R gain and B gain only for the included block again to detect white. The white balance calculated based on the block is obtained. Actually, in order to improve the accuracy, the final white balance is determined in consideration of various information and conditions such as brightness information and distance information to the subject.
The above is the basic operation of the AWB control program. Next, the AWB reliability determination program will be described.

As described above, the AWB control program finds a white (achromatic) portion in the screen and performs control such that the signal of that portion becomes R = B = G. Therefore, when there is no white (achromatic color) portion in the screen, or when there are few white (achromatic color) portions, the reliability is low. In addition, when the shooting scene is assumed (environmental determination) based on the information on the illuminance of the subject and the focus position (focus position), and the white balance that seems to be optimal and the AWB result are significantly different, the reliability of the AWB is low. Conceivable. Here, the AWB reliability determination shows a process of determining the reliability based on the number of white detection blocks (subroutine: “white balance reliability calculation process”).
FIG. 5 is a flowchart showing an example of an operation sequence of a subroutine: “white balance reliability calculation processing”.
First, the R gain and B gain of each block of the entire screen are calculated by the method described above (step S21).
Next, how many of these blocks are included in the white detection range is counted (step S21).

Next, it is verified whether the total number of blocks included in the white detection range exceeds, for example, 15% of the total number of blocks (step S23). When exceeding, it determines with having reliability, sets a reliability determination flag to 1, and returns (step S24). If the number of blocks does not exceed 15% of the total number of blocks, it is determined that there is no reliability, and the reliability determination flag is set to 0 (step S25).
In this example, as a guideline for determining the reliability of white balance, 15% of the total number of blocks is set as a threshold. However, this threshold may be, for example, 20% of the total number of blocks, or the subject. Control may be performed to dynamically change the threshold according to conditions such as the brightness of the image. The reliability determination flag is a response parameter to the main routine (step S2 in FIG. 3) that performs the subsequent processing.
Next, a warning display (display in step S4 in FIG. 3) when it is determined that the reliability of AWB is low (in the case of flag 0) will be described. The purpose of this warning display is to notify the operator of information that the reliability of the AWB is low and to allow the operator to select whether or not to execute the WB detailed setting mode described later.

FIG. 6 is an explanatory diagram illustrating an example of a warning display screen.
The operator selects whether or not to perform detailed WB setting using the U / I (cross button or OK button) of the camera. If the operator chooses not to perform detailed WB settings (as shown in step S8 in FIG. 3), the RAW data is developed and obtained using the white balance parameters calculated by the AWB. The recorded JPEG data is recorded in the SDRAM 103.
Hereinafter, a WB detailed setting program that is executed when the operator selects the WB detailed setting on the warning display screen described above will be described.
FIG. 7 is an explanatory diagram showing a WB detailed setting screen displayed when the WB detailed setting program is executed.

In the WB detailed setting screen shown in FIG. 7, first, on the first screen, the result of developing the RAW data using the white balance parameter calculated by the normal AWB is displayed. At this time, a selection bar for setting a white balance suitable for various light sources (from the low color temperature side to the high color temperature side) is displayed on the left side of the screen. I can be used to change the white balance setting.
When the white balance is changed, the WB detailed setting program re-develops the RAW data using the changed WB parameter and displays the result. With this configuration, the operator can select a setting (second white balance parameter) that seems to be optimal while visually recognizing the WB change result. In addition, the operator selects the WB that seems to be optimal, and then operates the U / I (for example, presses the OK button), so that the operator selects the WB parameter calculated by normal AWB. With the WB parameters set in detail, two types of JPEG data obtained by developing RAW data are recorded in the SDRAM 103, respectively.
It is also possible to provide a mode in which development is performed using only the WB parameters set in detail by the operator and recording is not performed using the WB parameters calculated by the normal AWB.

FIG. 8 is a flowchart showing an example of an operation sequence of a subroutine: “WB detailed setting program”.
First, it is verified whether or not the setting is completed (whether or not the OK button shown in FIG. 7 is pressed). If the setting is completed, the process returns. If the setting is not completed, the process proceeds to step S32 (step S32). S31).
Next, it is verified whether the white balance has been changed (whether the selection bar shown in FIG. 7 has been operated). If the white balance has not been changed, the process returns to step S31, and the white balance has been changed. Advances to step S33 (step S32).
Next, the display of the WB detailed setting screen (FIG. 7) is updated, and the process returns to step S31 (step S33).

  In the imaging method according to the present invention, the imaging step is a step for performing processing similar to the processing executed by the imaging means for converting the optical image of the subject into an electrical signal. A step of performing a process similar to the process executed by the signal processing means for converting into one image data, and the auto white balance step determines and extracts a specific color portion relating to a color temperature change of the first image data, and at least The step of performing the same process as the process executed by the auto white balance unit that outputs the first white balance parameter with reference to the extracted data, and the data format conversion step is based on the input white balance parameter. Data format conversion means for converting the first image data into second image data that can be recorded and displayed The image recording step is a step for performing the same processing as the processing executed by the image recording means for storing the second image data in the information recording medium. The reliability determination step is a step of performing the same processing as the processing executed by the white balance reliability determination means for determining the reliability of the auto white balance control based on the first white balance parameter, and the white balance setting step is When the white balance reliability determination step determines that the reliability of the auto white balance control based on the first auto white parameter is low, a second white balance parameter different from the first white balance parameter White balun that allows the operator to set Setting means is a step of performing is similar to the process of execution.

In the auto white balance reliability warning step, when the white balance reliability determination means determines that the auto white balance reliability is low, the auto white balance reliability warning step notifies the operator that the auto white balance reliability is low. This is a step for performing the same processing as the processing executed by the white balance reliability warning means, and includes a warning message display step and / or a warning sound output step.
It should be noted that at least a part of the processing of each component of the imaging apparatus according to the present invention is executed by computer control, and the above processing is executed by the computer according to the procedures shown in the flowcharts of FIGS. The program shown may be distributed by storing it in a computer-readable recording medium such as a semiconductor memory, a CD-ROM, or a magnetic tape. A computer including at least a microcomputer, a personal computer, and a general-purpose computer may read the program from the recording medium and execute the program.

BRIEF DESCRIPTION OF THE DRAWINGS It is an external view of the imaging device which concerns on the 1st Embodiment of this invention, Fig.1 (a) shows a top view, FIG.1 (b) shows a front view, FIG.1 (c) shows a rear view, respectively. 1 is a block diagram illustrating a main circuit configuration of an imaging apparatus according to a first embodiment of the present invention. It is a flowchart which shows an example of the image processing sequence in the imaging device which concerns on this invention. 2 is an explanatory diagram showing a primary color Bayer array as an example of a configuration of a primary color filter mounted on the surface of a CCD 101. FIG. It is a flowchart which shows an example of the operation | movement sequence of subroutine: "White balance reliability calculation process" of the imaging device which concerns on this invention. It is explanatory drawing which shows an example of the warning display screen of the imaging device which concerns on this invention. It is explanatory drawing which shows the WB detailed setting screen displayed when a WB detailed setting program is performed. 9 is a flowchart showing an example of an operation sequence of a subroutine: “WB detailed setting program”.

Explanation of symbols

1 Sub LCD
2 Memory Card / Battery Loading Cover 3 Flash Unit 4 Optical Viewfinder 5 Distance Measuring Unit 6 Remote Control Light Receiver 7 Lens Unit 8 AF LED
9 Strobe LED
10 LCD Monitor 13 Power Switch 71 Lens Unit 72 Aperture 75 Motor Driver 101 CCD
102 F / E-IC
1021 CDS
1022 AGC
1023 A / D converter 103 SDRAM
104 signal processing unit 1041 CCD interface unit 1042 memory controller 1043 CPU
1044 YUV conversion unit 1045 Compression / decompression unit 1046 Display output control unit 1047 Resize processing unit 1048 Media I / F (interface) unit 105 Operation unit 106 ROM
107 memory card

Claims (12)

An image pickup unit that converts an optical image of a subject into an electrical signal, a signal processing unit that converts the electrical signal into first image data, and a specific color portion relating to a color temperature change in the first image data is determined and extracted. Auto white balance means for outputting a first white balance parameter with reference to at least this extracted data, and second image data capable of recording and displaying the first image data based on the inputted white balance parameter In an imaging apparatus, comprising: a data format conversion means for converting the image data; and an image recording means for storing the second image data in an information recording medium.
White balance reliability determining means for determining reliability of auto white balance control based on the first white balance parameter;
When the white balance reliability determination means determines that the reliability of the auto white balance control based on the first auto white parameter is low, a second white balance parameter different from the first white balance parameter is set. A white balance setting means for the operator to set,
When it is determined that the reliability of the auto white balance control based on the first auto white parameter is low, at least the second image data based on the second white balance parameter is recorded on the information recording medium. An imaging apparatus characterized by the above. 2. The imaging according to claim 1, wherein the white balance reliability determination unit refers to a determination extraction result of a specific color portion related to a color temperature change of the first image data output from the auto white balance unit. apparatus. The white balance reliability determination means detects white pixels of the first image data, and determines that the white balance reliability is low when at least the ratio of the white pixels is equal to or less than a predetermined value. The imaging apparatus according to claim 1, wherein the imaging apparatus is characterized. An auto white balance reliability warning means for notifying the operator that the reliability of the auto white balance is low when the white balance reliability determination means determines that the reliability of the auto white balance is low. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is an image pickup apparatus. 5. The image pickup apparatus according to claim 1, wherein the auto white balance reliability warning unit includes a warning message display unit and / or an alarm sound output unit. 6. 6. The white balance setting means, as an initial screen, displays the second image data based on the first white balance parameter together with a selection bar for setting white balance. The imaging device according to any one of the above. An imaging step for converting an optical image of a subject into an electrical signal, a signal processing step for converting the electrical signal into first image data, and a specific color portion relating to a color temperature change in the first image data are determined and extracted. An auto white balance step for outputting a first white balance parameter with reference to at least the extracted data, and a second image data capable of recording and displaying the first image data based on the inputted white balance parameter In an imaging method, comprising: a data format conversion step for converting into an image recording step; and an image recording step for storing the second image data in an information recording medium.
A white balance reliability determination step for determining reliability of auto white balance control based on the first white balance parameter;
When it is determined by the white balance reliability determination step that the reliability of the auto white balance control based on the first auto white parameter is low, a second white balance parameter different from the first white balance parameter is set. A white balance setting step for the operator to set,
When it is determined that the reliability of the auto white balance control based on the first auto white parameter is low, at least the second image data based on the second white balance parameter is recorded on the information recording medium. An imaging method characterized by the above. The imaging according to claim 7, wherein the white balance reliability determination step refers to a determination extraction result of a specific color portion related to a color temperature change of the first image data output from the auto white balance step. Method. The white balance reliability determination step detects white pixels of the first image data, and determines that the reliability of white balance is low when at least the ratio of the white pixels is equal to or less than a predetermined value. 9. The imaging method according to claim 7, wherein the imaging method is characterized. The white balance reliability determination step further includes an auto white balance reliability warning step for notifying the operator that the reliability of the auto white balance is low when it is determined that the reliability of the auto white balance is low. The imaging method according to any one of claims 7 to 9, wherein: 11. The imaging method according to claim 7, wherein the auto white balance reliability warning step includes a warning message display step and / or an alarm sound output step. 12. The white balance setting step displays, as an initial screen, the second image data based on the first white balance parameter together with a selection bar for setting white balance. The imaging method according to any one of the above.