JP3939899B2 - White balance adjustment device for electronic still camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus that is provided in an electronic still camera and performs white balance adjustment on an image obtained by photographing.
[0002]
[Prior art]
As a conventional electronic still camera, it is configured such that white balance adjustment can be automatically performed on image data recorded on a recording medium in accordance with the color temperature of illumination light such as sunlight or fluorescent light. Is known. That is, in normal shooting, white balance adjustment is always performed automatically, and automatic white balance adjustment can be prohibited by operating the operation switch. For example, when it is not desired to automatically adjust the white balance such as a sunset scene, the operation switch may be operated and adjusted manually.
[0003]
[Problems to be solved by the invention]
However, the work of adjusting the white balance adjustment by manual operation in this way is complicated, and there is a problem that changing the degree of white balance adjustment according to the subject requires skill.
[0004]
The present invention has been made for the purpose of providing a white balance adjustment device capable of changing the degree of white balance adjustment in accordance with a subject.
[0005]
[Means for Solving the Problems]
A first white balance adjusting apparatus according to the present invention includes a colorimetric means for detecting a color component included in light around an electronic still camera, and a white balance correction coefficient calculation for obtaining a white balance correction coefficient based on the color component. And white balance correction coefficient changing means for changing the white balance correction coefficient so that the effect of white balance adjustment is weakened.
[0006]
The white balance correction coefficient changing means may obtain a date / time of entry / exit from position information on the earth regarding the electronic still camera, and may change the white balance correction coefficient based on the photographing time and the date / time of entry / exit. In this configuration, it is preferable that the white balance correction coefficient changing means changes the white balance correction coefficient when the photographing time is within a predetermined time before and after the daylighting time. According to this, the degree of white balance adjustment in an image of sunset or sunrise is weakened, and an image in which redness such as sunset is emphasized can be obtained.
[0007]
The white balance correction coefficient changing unit may obtain position information on the earth regarding the electronic still camera by a global positioning system. According to this, the position of the electronic still camera is automatically detected, and it is automatically estimated whether or not the subject includes a sunset or the like based on the position and the shooting time. Is even easier.
[0008]
Colorimetric means red, glyceraldehyde - detecting the color components, red white balance correction coefficient calculation means, glyceraldehyde - - emission and Bull calculated white balance correction for coefficient K _R, K _G, a K _B, respectively - down and Bull The white balance adjustment means may be changed so that the white balance correction coefficients K _R , K _G , and K _B approach 1 when K _R <K _G and K _R <K _B.
[0009]
A second white balance adjusting device according to the present invention includes a white balance correction coefficient computing unit that detects a color component included in light around an electronic still camera and obtains a white balance correction coefficient, and an earth related to the electronic still camera. White balance correction coefficient changing means is provided for obtaining the altitude of the sun from the position information and the date and time, and changing the white balance correction coefficient based on the sun altitude.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a state in which an electronic still camera to which an embodiment of the present invention is applied is viewed from behind.
[0011]
This electronic still camera is a single-lens reflex camera, and the interchangeable lens 11 is detachably attached to the camera body 90. An optical viewfinder 91 is provided at the center of the upper portion of the camera body 90, and a liquid crystal panel (liquid crystal display element) 46 is provided at the approximate center of the back surface 92. On the liquid crystal panel 46, an image obtained by the interchangeable lens 11 that is a photographing optical system is displayed as a moving image, and a still image stored in a memory (not shown) can be displayed by a photographing operation. A mode setting switch 95 is provided beside the liquid crystal panel 46. The mode setting switch 95 is provided for setting various operation modes, and is a jog dial in the illustrated embodiment.
[0012]
When the camera body 90 is viewed from the back 92 side, a shutter button 93 and a status display device 55 are provided on the right side of the upper part of the camera body 90. The status display device 55 includes a liquid crystal display element, and various setting states of the electronic still camera are displayed on the liquid crystal display element as characters or symbols.
[0013]
A card slot 96 is formed on the side surface of the camera body 90. The card slot 96 is provided for inserting a PC card (memory card) into the camera body 90, and a card connector (not shown) into which the PC card is inserted is provided inside the card slot 96.
[0014]
A global positioning system (GPS) unit 80 is attached to the lower surface of the camera body 90. The GPS unit 80 is provided with a processor for detecting position information (latitude, longitude) on the earth regarding the electronic still camera based on the distance from an artificial satellite or the like. A memory is provided for storing the date and time data of the day.
[0015]
A distance measuring sensor 94 is provided on the upper surface of the optical viewfinder 91. The distance measuring sensor 94 includes an infrared light emitting element and an infrared light receiving element (not shown). Infrared light is emitted from the light emitting element, reflected from an obstacle such as a ceiling, and received by the light receiving element. The distance is measured.
[0016]
FIG. 2 is a block diagram mainly showing an electrical configuration of the electronic still camera.
The interchangeable lens 11 is electrically connected to an electric circuit provided in the camera body 90 (FIG. 1) via mount pins 12 and 13. A front lens group 14 and a rear lens group 15 are provided in the lens barrel of the interchangeable lens 11, and a diaphragm 16 is disposed between these lenses 14 and 15. The lenses 14 and 15 are displaced in the direction of the optical axis under the control of the lens control circuit 17 to perform focus adjustment. The lens control circuit 17 operates in accordance with a control signal sent from the system controller 31 provided in the camera body via the mount pin 12. The aperture 16 operates in accordance with a control signal sent from the aperture drive circuit 32 provided in the camera body via the mount pin 13, and the opening of the aperture 16 is adjusted. The aperture drive circuit 32 is controlled by the system controller 31.
[0017]
A half mirror 21 is provided on the optical axis of the lenses 14 and 15 in the camera body. The half mirror 21 is fixed at a position inclined by about 45 degrees with respect to the optical axes of the lenses 14 and 15. A focus plate 22 is provided above the half mirror 21, and a pentaprism 23 is provided above the focus plate 22. A finder eyepiece 24 is disposed behind the pentaprism 23. Therefore, the light taken in from the lenses 14 and 15 is reflected by the half mirror 21 and guided to the pentaprism 23 side, and the subject image is observed through the eyepiece lens 24.
[0018]
An infrared cut filter 26 and an optical low-pass filter 27 are provided behind the half mirror 21. A CCD (imaging device) 33 is provided behind the optical low-pass filter 27. Therefore, the light taken in from the lenses 14 and 15 passes through the half mirror 21 and is irradiated on the light receiving surface of the CCD 33. That is, an image obtained by the lenses 14 and 15 is formed on the light receiving surface, and the CCD 33 generates an imaging signal corresponding to the image.
[0019]
A pulse signal generation circuit (PPG) 36 is connected to the system controller 31, and the pulse signal generation circuit 36 generates various pulse signals under the control of the system controller 31. Based on these pulse signals, the CCD drive circuit 37, the A / D converter 38, and the image signal processing circuit 39 are driven, and the CCD drive circuit 37 controls the operation of the CCD 33. That is, the image pickup signal read from the CCD 33 is converted into a digital signal by the A / D converter 38 and subjected to predetermined image processing in the image signal processing circuit 39. The image signal processing circuit 39 is connected to a memory 40 having a sufficient capacity for storing digital image data corresponding to one image.
[0020]
A monitor interface 41 and a card interface 42 are connected to the image signal processing circuit 39. These interfaces 41 and 42 are controlled by the system controller 31.
[0021]
A backlight 45 and a liquid crystal panel 46 are connected to the monitor interface 41 via a liquid crystal drive circuit 44. In the liquid crystal panel 46, as described above, the liquid crystal driving circuit 44 is controlled based on the image pickup signal read from the CCD 33, whereby the image obtained by the interchangeable lens 11 is displayed as a moving image, and the memory 40 The liquid crystal driving circuit 44 is controlled based on the image data read out from, and a still image is displayed. A card connector 47 is connected to the card interface 42, and a PC card 43 can be attached to the card connector 47.
[0022]
An AF sensor 51, a photometric sensor 52, an auto white balance (AWB) sensor 97, and a distance measuring sensor 94 are connected to the system controller 31. The AF sensor 51 has a conventionally known configuration, and the AF sensor 51 measures the focus adjustment state of the lenses 14 and 15. The photometric sensor 52 performs photometry to determine the opening of the diaphragm 16 at the time of exposure and the charge accumulation time (exposure time) in the CCD 33. The auto white balance sensor 97 has a light receiving sensor (not shown) for detecting red (R), green (G) and blue (B) light components, and the auto white balance. Used in adjustment. As described above, the distance measuring sensor 94 measures the distance from the upper surface of the camera body 90 to the obstacle, and is used to determine whether it is outdoor shooting or indoor shooting as will be described later.
[0023]
The system controller 31 is connected to a photometric switch 53, a release switch 54, and a status display device 55. The metering switch 53 is turned on by half-pressing the shutter button 93, whereby the metering sensor 52 performs metering. The release switch 54 is turned on when the shutter button 93 is fully pressed, whereby the imaging operation of the CCD 33 is started, and an imaging signal corresponding to the image is generated in the CCD 33.
[0024]
Further, a mode setting switch 95 is connected to the system controller 31. As described above, the mode setting switch 95 is a jog dial. When the mode setting switch 95 is pressed at a rotational position corresponding to the operation mode, the operation mode is set. The operation mode includes a manual white balance adjustment mode.
[0025]
A GPS interface 56 is connected to the system controller 31. The GPS interface 56 is connected to the image signal processing circuit 39 and the GPS unit 80. The date / time data detected by the GPS unit 80 is transmitted to the image signal processing circuit 39 via the GPS interface 56. In the image signal processing circuit 39, the image data read from the CCD 33 is subjected to white balance adjustment and stored in the memory 40. The effect of the white balance adjustment is based on the daylighting time and the photographing time. Can be weakened.
[0026]
FIG. 3 is a flowchart of a photographing mode discriminating routine for discriminating whether photographing is performed outdoors or indoors. This program is executed in the system controller 31.
[0027]
In step 101, the distance measuring sensor 94 is driven, and the spatial distance H to the obstacle located on the upper surface of the camera body 90 is detected. As an obstacle, in indoor photography, it is often the ceiling of the room, often not present in outdoor photography, and even if it exists, it is often higher than the ceiling of a normal building.
[0028]
In step 102, it is determined whether or not the spatial distance H is equal to or less than a predetermined value. The predetermined value is larger than the ceiling height of a normal building, for example, 5 m. When it is determined in step 102 that the spatial distance H is greater than the predetermined value, that is, when it is determined that there is no obstacle such as a ceiling in a relatively close position above the electronic still camera, step 103 is executed, It is presumed that the electronic still camera is currently outdoors, and the outdoor shooting mode is set. On the other hand, when it is determined in step 102 that the spatial distance H is equal to or smaller than the predetermined value, step 104 is executed, and it is estimated that the electronic still camera is currently in the room, and the indoor shooting mode is set. When the photographing mode is selected in step 103 or 104, this routine ends.
[0029]
4 to 5 are flowcharts of a photographing operation control routine which is a program for controlling the photographing operation in the outdoor photographing mode. This program is executed in the system controller 31.
[0030]
Step 201 is repeatedly executed until it is confirmed that the photometric switch 53 is set to the on state. When the photometric switch 53 is set to the on state, a photometric calculation is executed in step 202. That is, based on the photometry performed by the photometry sensor 52, the opening of the diaphragm 16 and the charge accumulation time (exposure time) in the CCD 33 are determined.
[0031]
In step 203, red (R), green (G), and blue (B) color components included in the ambient light of the electronic still camera are detected by the AWB sensor 97, and colorimetric calculation is performed. white balance correction coefficient K _R, K _G, is K _B obtained. White balance correction coefficient K _R, K _G, K _B, in order to perform the white balance adjustment, red read from CCD 33, glyceryl - emission and Blu - pixel data of - those to be multiplied to the other. That is, for example, in photographing using illumination light with a low color temperature, since the red color component is relatively large in the ambient light of the electronic still camera, the red white balance correction coefficient K is set to reduce the level of the red pixel signal. _R is set to a value smaller than 1.
[0032]
In step 204, it is determined whether or not K _R <K _G and K _R <K _B. K _R <K _G and K _R <K _B are satisfied at the same time when the red component is less than the green and blue components in the ambient light of the electronic still camera. There is a high possibility that it is time to shoot in the situation. In this case, the process proceeds to step 205. On the other hand, when K _R <K _G and K _R <K _B are not satisfied at the same time, it is unlikely that the image is shot at sunset or sunrise, and step 208 is executed, and white balance correction coefficients K _R , K _G , the correction factor to be multiplied to K _B alpha is determined to one.
[0033]
In step 205, position information on the earth regarding the electronic still camera, that is, information on the place where the image is being taken is acquired from the GPS unit 80. In step 206, based on the position information, the date / time of the shooting date is calculated from the data of the date / time of entry stored in the memory provided in the GPS unit 80. In step 207, it is determined whether or not the current time (that is, the photographing time) is within a predetermined time (for example, ± 30 minutes) before or after the sunrise or sunset time. The current time is detected by a clock (not shown) provided in the electronic still camera.
[0034]
When the current time is within a predetermined time period before and after the times of sunrise and sunset, K _R <K _G and K _R <determined to be caused to be K _B in step 204 is presumed to be a sunset or sunrise, Step 209 is executed. That is, the correction coefficient α is set to 0.3 so that the white balance correction coefficients K _R , K _G , and K _B obtained based on the detection result of the AWB sensor 97 are close to 1. On the other hand, when the current time is not within a predetermined time before and after the daylighting time, step 208 is executed and the correction coefficient α is set to 1. That the white balance correction coefficients K _R, K _G, K _B is not changed. The correction coefficient α may be determined by the following equation according to the time Δt until sunrise or sunset.
α = Δt (min) / 100 (min) (when 0 <Δt <100 (min))
α = 1 (when Δt ≧ 100 (minutes))
[0035]
After execution of step 208 or 209, in step 211, it is determined whether or not the release switch 54 is set to the on state. While the release switch 54 is in the off state, step 212 is executed to determine whether or not the photometric switch 53 has been switched to the off state. When the photometric switch 53 is switched to the off state, that is, when the shutter button 93 is released, this routine ends. When the photometric switch 53 is kept on, Step 211 is executed again. If the release switch 54 is turned on while steps 211 and 212 are repeatedly executed, the process proceeds to step 213.
[0036]
In step 213, shooting is performed, and the CCD 33 generates an imaging signal corresponding to the image. The imaging signal is read from the CCD 33 and converted into a digital signal, which is input to the image signal processing circuit 39. In step 214, new white balance correction coefficients K _R , K _G , and K _B are obtained according to the equation (1) using the correction coefficient α obtained in step 208 or 209.
K _N = (K _N −1) · α + 1 (1)
Here, K _N is any one of K _R , K _G , and K _B , that is, the expression (1) is applied to all white balance correction coefficients.
[0037]
For example, when the original correction coefficient K _N = 2 and α = 0.3, the new correction coefficient is K _N = (2-1) · 0.3 + 1 = 1.3
It becomes. Also, when the original correction coefficient K _N = 0.5 and α = 0.3, the new correction coefficient is K _N = (0.5-1) · 0.3 + 1 = 0.85
It becomes. Thus, by using the correction coefficient α set in step 208, the white balance correction coefficients K _R , K _G , and K _B approach 1 and the effect of white balance adjustment is weakened.
[0038]
In step 215, the new white-balance correction coefficient K _R determined at step 214, K _G, with K _B, the image signal or pixel des read from CCD 33 - white balance adjustment is made to the data. In step 216, a color image is displayed on the liquid crystal panel 46 in accordance with the pixel data adjusted for white balance. This pixel data is recorded in the PC card 43 in step 217, and this routine is completed.
[0039]
On the other hand, the shooting operation control routine in the indoor shooting mode omits steps 204 to 209 and 214 in the flowcharts of FIGS. 4 to 5 and changes the contents of step 215 to “white balance correction coefficient K”. _R, it is obtained by the K _G, the white balance adjustment is performed using a K _B ".
[0040]
The manual / white balance adjustment mode is set by operating the mode setting switch 95. In this case, the white balance correction coefficient is determined by the photographer's operation.
[0041]
As described above, according to the present embodiment, white balance adjustment is simplified, and the degree of white balance adjustment can be changed according to the subject. In the present embodiment, the date / time of entry / exit is obtained from the position information on the earth regarding the electronic still camera, and the white balance correction coefficient is changed based on the shooting time and the date / time of entry / exit, so that white balance adjustment in an image of sunset or sunrise can be performed. An image in which redness such as sunset is emphasized can be obtained by reducing the degree. Further, in the present embodiment, since the global positioning system obtains the position information on the earth regarding the electronic still camera using the GPS unit 80, the position of the electronic still camera is automatically detected, and based on the position and the shooting time. Thus, since it is automatically estimated whether or not the subject includes a sunset or the like, it is further easy to change the white balance adjustment.
[0042]
Instead of the GPS unit 80, the photographer may input the information on the shooting location to the electronic still camera, obtain the date and time of entry based on this information, and change the white balance correction coefficient. .
[0043]
Furthermore, instead of determining whether outdoor shooting or indoor shooting is performed based on a signal from the distance measuring sensor 94, the photographer may set it by operating the mode setting switch 95 or the like.
[0044]
【The invention's effect】
As described above, according to the present invention, the degree of white balance adjustment can be changed according to the subject.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a state in which an electronic still camera to which an embodiment of the present invention is applied is viewed from the rear.
FIG. 2 is a block diagram mainly showing an electrical configuration of an electronic still camera.
FIG. 3 is a flowchart of a photographing mode discriminating routine for discriminating whether photographing is performed outdoors or indoors.
FIG. 4 is a first half of a flowchart of a shooting operation control routine that is a program for controlling a shooting operation in an outdoor shooting mode.
5 is the latter half of the flowchart of the photographing operation control routine shown in FIG. 4;
[Explanation of symbols]
80 GPS unit 97 Auto white balance sensor

Claims (5)

An apparatus for performing white balance adjustment on an image obtained by an electronic still camera, a color measurement unit for detecting a color component included in light around the electronic still camera, and a white balance correction coefficient based on the color component White balance correction coefficient calculating means for obtaining the white balance correction coefficient changing means for changing the white balance correction coefficient based on the shooting time and the date and time of entry / exit so that the effect of the white balance adjustment is weakened. balanced correction coefficient changing means, when in a predetermined time before and after the shooting time of sunrise and sunset time, as the photographing time and sunrise effect of the time difference white balance adjustment the smaller of the input and time weakens, the following formula change the white balance correction coefficient based on the time difference Do not fall within the predetermined time period In this case, the white balance adjustment apparatus for an electronic still camera characterized in that it does not change the white balance correction coefficient.
K _N = (K _N −1) · α + 1
Where K _N is a white balance correction coefficient, and α is a correction coefficient of 1 or less.   2. The white balance adjustment apparatus according to claim 1, wherein the white balance correction coefficient changing unit obtains a date and time of entry and exit from position information on the earth regarding the electronic still camera.   The white balance adjustment apparatus according to claim 2, wherein the white balance correction coefficient changing unit obtains position information on the earth by a global positioning system. Said colorimetric means red, glyceraldehyde - emission and table - for detecting the color components, the white balance correction coefficient calculating means red, glyceraldehyde - emission and Bull - white balance correction for coefficient K _R, K _G, a K _B Each of the white balance adjustment means is obtained so that the white balance correction coefficients K _R , K _G , and K _B are changed to approach 1 when K _R <K _G and K _R <K _B. The white balance adjustment device according to claim 1. A device for performing white balance adjustment on an image obtained by an electronic still camera, white balance correction coefficient calculating means for detecting a color component included in light around the electronic still camera and obtaining a white balance correction coefficient; White balance correction coefficient changing means for obtaining a date / time of entry / exit from the position information on the earth on the electronic still camera, and changing the white balance correction coefficient based on the photographing time and the date / time of entry / exit, and the white balance correction coefficient Based on the following formula, the changing means is such that when the shooting time is within a predetermined time before and after the daylight access time, the effect of white balance adjustment is weaker as the time difference between the shooting time and the daylight access time is smaller. When the white balance correction coefficient is changed and the time difference is not within the predetermined time White balance adjusting apparatus of an electronic still camera which is characterized not to change the white balance correction coefficient.
K _N = (K _N −1) · α + 1
Where K _N is a white balance correction coefficient, and α is a correction coefficient of 1 or less.