JP2002185972A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device which does not require a white paper, etc., and which can easily set precise white balance. SOLUTION: In a digital camera provided with a liquid crystal monitor 50, an image part (a part near gray) showing saturation equal to or lower than a previously fixed threshold is detected with respect to an image obtained through an imaging device such as a CCD and the image part is overlay- displayed by a special fixing pattern such as a zebra mark, half-tone dot meshing. The monitor 50 is capable of displaying GUI for designating the correcting quantity of white balance and a photographing person can set white balance by using the GUI so that the mark 152 is entered to a part of the achromatic subject within an imaging scene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image pickup apparatus, and more particularly to a white balance correction technique applied to an electronic camera capable of setting white balance correction manually.

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 2000-115588 discloses an image pickup apparatus capable of selecting a manual white balance mode and an automatic (automatic) white balance mode. A display to that effect is displayed.

As a method of manually adjusting white balance (WB) in a conventional electronic camera, a photographer is caused to select a light source mode (color temperature) such as "sunny", "cloudy", "bulb", or "fluorescent". There is a way. There is also a method called “preset WB” in which a button is pressed when white paper or the like is imaged to obtain a white balance.

[0004]

However, according to the method of selecting the light source mode, the white balance is set in the case of an intermediate weather between "sunny" and "cloudy" or for a fluorescent lamp of a type not supported by the menu. There is a disadvantage that cannot be set accurately. The method using the preset WB is a relatively reliable method, but the setting operation is complicated, for example, white paper must be prepared.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an imaging apparatus which does not require white paper or the like and can easily and accurately set a white balance.

[0006]

According to another aspect of the present invention, there is provided an image pickup apparatus that converts an optical image into an electric signal and outputs an image signal indicating a subject image.
A signal processing unit that processes an image signal obtained by the imaging unit to convert the image signal into electronic image data; an image display unit that displays an image based on the electronic image data; and a color of an image obtained through the imaging unit. A white balance adjustment circuit for adjusting the gain of the signal; and a gray area for detecting the saturation of the image obtained through the imaging means and extracting an image portion having a saturation smaller than a preset threshold value. Extraction means, and display contents of the image display means so as to perform display to distinguish the image part near the achromatic color extracted by the gray area extraction means from other areas using a predetermined display pattern. And display control means for controlling.

According to the present invention, a portion near gray in an image is detected from color information of a captured scene, and a special pattern (zebra mark, shading, etc.) different from normal color reproduction display for the portion near gray is detected. Is displayed as an overlay so that the photographer (operator) can easily grasp the state of the white balance. It is also preferable that the threshold value is added by a means that allows the operator to arbitrarily specify the threshold value.

According to another aspect of the present invention, as the means for specifying an amount of white balance correction in the white balance adjustment circuit by an operator, the image display means corrects the white balance correction amount. GU for quantity specification
I (graphical user interface) is displayed.

[0009] The photographer can arbitrarily set the white balance using the GUI so that a predetermined display pattern is applied to the achromatic subject in the image displayed on the image display means. This makes it possible to easily and accurately set the white balance.

According to a fourth aspect of the present invention, there is provided an image pickup apparatus for converting an optical image into an electric signal and outputting an image signal representing a subject image, and processing the image signal obtained by the image pickup means into electronic image data. A signal processing unit for converting, an image display unit for displaying an image based on the electronic image data, a white balance adjustment circuit for adjusting a gain of a color signal of the image obtained via the imaging unit, and the image display unit Image position designating means for an operator to designate an image position at which a white balance is to be taken in the image displayed on the screen, and the white balance adjusting circuit so that the position designated by the image position designating means becomes achromatic. And control means for controlling

According to the present invention, the image position which the photographer intends to achieve the white balance among the images displayed on the screen of the image display means can be arbitrarily designated by the image position designation means. The white balance is automatically adjusted so that the designated image position becomes gray.
This makes it possible to easily set a desired white balance.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of an image pickup apparatus according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an external perspective view of a digital camera according to an embodiment of the present invention. A photographing lens 14, a finder window 16, a strobe light emitting unit 20, and the like are provided on the front surface of the camera 10, and a CCD image sensor (denoted by reference numeral 78 in FIG. 3) is arranged behind the photographing lens 14. Reference numeral 18 denotes a grip portion, reference numeral 24 denotes a strobe light control sensor, and reference numeral 26 denotes a self-timer lamp.

A shutter button 28 for instructing the start of photographing and a liquid crystal display panel 30 are provided on the upper surface of the camera 10, and a flash button 32 and a macro button 34 are provided beside the liquid crystal display panel 30. The shutter button 28 is of a two-stage type, and when the shutter button 28 is lightly pressed and stopped, the automatic focusing (AF) and the automatic exposure control (AE) are activated in the state of "AF and A".
Lock E and push further from "half-press""full-press"
The shooting is performed in the state of.

The liquid crystal display panel 30 displays information relating to the status of the camera, the shooting mode, and the like. And information such as recording image quality (quality) display and pixel number display.

The flash button 32 is used to set the flash to "automatic flash", "red eye reduction",
These are operation keys for setting each mode such as “forcible light emission” and “light emission inhibition”. The macro button 34 is an operation key for setting / releasing a short-distance (macro) shooting mode.

A recording medium (reference numeral 11 in FIG. 3) is provided on the right side (the side opposite to the grip 18) of the camera 10 in FIG.
8) is provided. A media cover 38 for covering the insertion port 36A is provided at the insertion port 36A of the media socket 36 so as to be freely opened and closed. When the media cover 38 is closed, the engaging means 39 holds the media cover 38 in a closed state. When the knob 40 is slid downward in FIG.
8 is released.

As shown in FIG. 1, the media socket 3
6, a power input (DC IN 5V) terminal 42, an image output (VIDEO OUT) terminal 44, a digital input / output terminal 46
Is provided.

FIG. 2 is a rear view of the camera 10 shown in FIG. On the back of the camera, an LCD monitor 50, a power switch 52, a mode dial 54, a cross button (up / down / left / right keys) 56, a viewfinder 58, and a custom button 6
0, a display button 62 and a menu / execute button 64 are provided.

The liquid crystal monitor 50 can be used as an electronic finder for confirming the angle of view at the time of photographing, and can display a preview image of the photographed image, a reproduced image read from the recording medium 118 loaded in the camera 10, and the like. . The menu selection using the cross button 56 and the setting of various setting items in each menu are also performed by the liquid crystal monitor 5.
This is performed using the display screen of “0”.

The mode dial 54 is arranged on the outer periphery of the cross button 56, and can change the function (mode) of the camera depending on the setting position of the dial. For example, on the mode dial 54, "SETUP", "self-timer", "manual shooting", "auto shooting", "playback", and "erase (ERAS)"
E), “Image protection (protection)”, “PC (P
Symbols or characters indicating the eight modes of “C) connection” are sequentially formed. A symbol or a character representing a desired function is used as an index 7
The mode is set by setting the value to 0.

A triangular mark 72 indicating four directions of up, down, left and right is formed on the cross button 56. By pressing the vicinity of any one of these triangular marks 72, the cross button 56 is tilted. Direction (up, down,
Right, left) instructions can be entered. The cross key 56 functions as an operation button for selecting a menu item from a menu screen displayed by pressing a menu / execute key 58, and for instructing selection of various setting items in each menu and change of setting contents. It is used as a means for adjusting the magnification of the electronic zoom, instructing the movement of the center of the zoom, and instructing the forward / backward of the playback frame.

The display button 62 turns on the liquid crystal monitor 50
This is an operation means for performing a / OFF operation and switching between display / non-display of a reproduction method and a frame number being reproduced. The menu / execute button 64 is used when a transition is made from the normal screen of each mode to the menu screen, when the selection is confirmed, and when a process execution (confirmation) instruction is issued.

FIG. 3 is a block diagram showing the configuration of the digital camera of this embodiment. The photographing lens 14 may be a single focus lens or a variable focal length lens such as a zoom lens. After the amount of light passing through the photographing lens 14 is adjusted by an aperture / shutter 74, the light is adjusted by an infrared cut filter 76 and an optical low-pass filter 77.
An image is formed on an image sensor (hereinafter, referred to as a CCD) 78. Photosensors are arranged in a plane on the light receiving surface of the CCD 78, and primary color filters of red (R), green (G), and blue (B) are arranged in a predetermined arrangement corresponding to each sensor. In this example, the RGB primary color filter type C
Although a CD (single-plate type) is used, a complementary color filter type CCD of magenta (Ma), yellow (Ye), green (G), and cyan (Cy) may be used. There is also a mode (double-plate type) in which a color separation optical system using a prism is mounted and an imaging device is provided for each of RGB colors.

The subject image formed on the light receiving surface of the CCD 78 is converted by each photosensor into an amount of signal charge corresponding to the amount of incident light. The CCD 78 has a so-called electronic shutter function of controlling the charge accumulation time (shutter speed) of each photosensor by the timing of a shutter gate pulse.

The signal charge stored in each photo sensor is
The signals are sequentially read out as voltage signals (image signals) corresponding to the signal charges based on the pulses given from the CCD driver 80. The image signal output from the CCD 78 is sent to a CDS circuit 82, which performs a correlated double sampling (CDS) process and a color separation process.

The image signal processed by the CDS circuit 82 is
After being converted into a digital signal by the A / D converter 84,
Stored in the memory 86. Timing generator (T
G) 88 supplies a timing signal to the CCD driver 80, the CDS circuit 82, and the A / D converter 84 according to a command from the CPU 90, and the circuits are synchronized by the timing signal.

The data stored in the memory 86 is transmitted to the bus 9
2 to the signal processing unit 94. Signal processing unit 94
Are white balance (WB) adjustment circuit 96, linear matrix circuit 98, gamma conversion circuit 100, RGB →
YCr Cb conversion circuit (hereinafter, referred to as YC conversion circuit) 1
02, an image processing means including a YCr Cb matrix circuit 104, a compression / expansion circuit 106 and the like, and processes an image signal according to a command from the CPU 90.

The WB adjustment circuit 96 is composed of a multiplier for increasing or decreasing the digital value of each of the RGB color signals, and each color signal is added to a corresponding multiplier. The white balance correction values (gain values) Rg, Gg, and Bg are given from the CPU 90 to the multipliers for the respective colors, and the multipliers adjust the color signal levels according to the instructions. The R, G, B signals white-balance adjusted by the white balance adjustment circuit 96 are sent to the linear matrix circuit 98.

The linear matrix circuit 98 converts the input RGB data according to the following equation (1),
Obtain GB data.

[0031]

(Equation 1) Here, a to i are constants.

The primary color signal obtained by the processing of the WB adjustment circuit has a value affected by the spectral transmittance of the CCD color filter.
Correction coefficient (a) corresponding to the spectral transmittance of the color filter
The matrix operation is performed based on .about.i). As a result, a color tone that cannot be reproduced only by the color separation characteristics of the CCD color filter can be reproduced.

The image data corrected by the linear matrix circuit 98 is applied to a gamma conversion circuit 100.
After the input / output characteristics are converted by the gamma conversion circuit 100, the input / output characteristics are sent to the YC conversion circuit 102. YC conversion circuit 10
2 is a luminance signal (Y) based on the input RGB primary color data.
Signals) and color difference signals (Cr, Cb signals). YC
The luminance / color difference signals (Y, Cr,
Cb) is sent to the YCr Cb matrix circuit 104 and converted according to the following equation (2).

[0034]

(Equation 2) However, k to t are constants.

The color correction of the chroma signal is performed by the YCr Cb matrix circuit 104. The image data processed by the YCr Cb matrix circuit 104 is stored in the memory 8
6 is stored.

When displaying and outputting a photographed image, the memory 86
From the display memory (VRA).
M) 108. The data sent to the VRAM 108 is converted by the encoder 110 into a signal of a predetermined system for display (for example, a color composite video signal of the NTSC system).
After that, the data is output to a liquid crystal monitor (LCD) 50 via a D / A converter 112. Thus, the image content of the image data is displayed on the screen of the liquid crystal monitor 50.

The image data in the memory 86 is periodically rewritten by the image signal output from the CCD 78,
The video signal generated from the image data is transmitted to the liquid crystal monitor 5
By being supplied to 0, an image input via the CCD 78 is displayed on the liquid crystal monitor 50 in real time.
The photographer can check the image (through image) displayed on the liquid crystal monitor 50 or the shooting angle of view with the viewfinder 58.

When a shooting mode is set by the mode dial 54 and the shutter button 28 is pressed, a shooting start instruction (release ON) signal is issued. The CPU 90
In response to the reception of the instruction signal, the capture of the image data for recording is started. Also, the CPU 90 sends a command to the compression / expansion circuit 106, thereby
6 compresses the image data (Y, Cr, Cb) in the memory 86 in accordance with JPEG or another predetermined format.

The compressed image data is transmitted to the media interface 114 (media socket 36 shown in FIG. 1).
) Is recorded on the recording medium 118. In the camera 10 of this example, as means for storing image data, for example, smart media (Solid-State Floppy Disk Car
d) applies. The form of the recording medium 118 is not limited to this, and may be a PC card, a compact flash (registered trademark), a magnetic disk, an optical disk, a magneto-optical disk, a memory stick, or the like, and may be electronic, magnetic, optical, or any of these. Various readable and writable media can be used in accordance with a combination method. Signal processing means and interfaces corresponding to the medium used are applied. A configuration may be adopted in which a plurality of media can be mounted irrespective of different types or the same type of recording media. The means for storing the image file is not limited to a removable medium that can be attached to and detached from the camera body, but may be a recording medium (internal memory) built in the camera 10.

When the reproduction mode is set by the mode dial 54, an image file is read from the recording medium 118. The read image data is supplied to a compression / decompression circuit 8.
The video data is decompressed by the LCD 8 and output to the liquid crystal monitor 50 via the VRAM 108 and the encoder 110.

The CPU 90 is a control section for controlling the camera system. The CPU 90 controls the mode dial 5
4. Based on input signals received from the operation unit 120 such as the shutter button 28, the cross button 56, and the like, the operation of the corresponding circuit is controlled to control display on the liquid crystal monitor 50, strobe light emission control, auto focus (AF) control, And automatic exposure (AE) control and the like.

The CPU 90 performs various calculations such as a focus evaluation calculation and an AE calculation based on image data taken in response to half-pressing of the shutter button 28, and controls the lens driving unit 122 based on the calculation results. To move the photographing lens 12 to the in-focus position,
To set the aperture / shutter 74 to an appropriate aperture value, and at the same time, control the charge accumulation time of the CCD 78. An EEPROM (non-volatile memory) 126 stores data necessary for white balance correction, various setting information, and the like.
Various operations are performed with reference to the data in the OM 126.

The strobe device 130 includes a strobe light emitting unit 2
0, a strobe light control sensor 24, a capacitor 132, and a strobe control circuit 134. CPU 90
Gives a command to the flash control circuit 134 at the time of shooting, according to the flash mode selected by the operator. The strobe control circuit 134 controls the charge control of the capacitor 132 and the discharge (light emission) timing to the strobe light emitting unit 20 (for example, a xenon tube) based on a command applied from the CPU 90, and the detection result of the strobe light control sensor 24. The control of the light emission stop is performed based on. The strobe light sensor 24 uses a light receiving element that receives reflected light from a subject illuminated by the emission of the strobe light and converts the reflected light into an electric signal corresponding to the amount of received light. The detection signal of the strobe light control sensor 24 is integrated by an integrating circuit (not shown),
When the integrated amount of received light reaches a predetermined appropriate amount of received light, the emission of the strobe light is stopped.

As the power supply of the camera 10, an external power supply such as an AC power adapter (not shown) connected to the battery 140 or the power supply input terminal 42 can be used. The power supplied from the battery 140 and the like is converted to a required voltage by a power supply circuit 42 including a DC / DC converter, and then supplied to each circuit block.

Next, the white balance correction in the digital camera configured as described above will be described.

The CPU 90 detects the saturation of the picked-up image based on the image data obtained by the image pickup, and detects a zebra mark or other predetermined value for an image region having a saturation below a predetermined threshold value. Display control is performed so as to perform overlay display using the pattern (pattern). FIG.
Shows a display example. In the example shown in the figure, the hair portion of the boy 150, which is the main subject, is detected as an image region (a portion near gray) showing saturation below the threshold, and this portion is detected as a zebra mark 152 or another predetermined portion. The display is overcoated with the special pattern.

The threshold value is set to a value serving as a reference for determining whether or not the target image portion is close to an achromatic color (gray). The threshold can be appropriately set by the operator performing a predetermined operation such as operating the cross button 56 from the menu screen. In addition, in order to target a gray area closer to white, a threshold value may be provided for brightness (luminance) in addition to saturation, and an image portion brighter than the threshold value may be extracted.

The overlay display using such a special pattern can be performed in any of the automatic white balance mode and the manual white balance mode. The auto white balance mode is a mode in which a light source type is automatically determined from photographed image data and a white balance correction suitable for the light source type is automatically performed. Used to check the status. When a predetermined operation such as pressing a white balance confirmation button (not shown) is performed, an image portion having a saturation value equal to or lower than the threshold value is displayed in an overlay in a predetermined pattern. When the manual white balance mode is selected, the overlay display is performed.

The operator checks the white balance by looking at the overlay display shown in FIG. 4, and if it is determined that the white balance needs to be corrected, performs a predetermined operation to perform the white balance manual correction screen. Is displayed. FIG. 5 shows an example of the manual correction screen. A GUI (graphical user interface) 160 for specifying the correction amount is displayed on the screen of the liquid crystal monitor 50 so that the photographer can easily specify the correction amount of the white balance.

According to the figure, a menu for increasing or decreasing the gain for each of the R, G, and B color components is displayed at the bottom of the screen, and the operator operates the up / down key of the cross button 56. To adjust the numerical value of the shift amount (correction amount) of each of R, G, and B. The gain of the white balance adjustment circuit is changed in accordance with the adjustment of the correction amount, and the hue of the monitor image changes accordingly. When the desired white balance is obtained, the adjustment operation is completed.

The subjects include human hair, eyebrows, roads,
Achromatic subjects such as telephone poles, walls, white and gray clothing, and concrete are likely to be shown together. Therefore, if the white balance is set from the GUI 160 such that the achromatic subject is displayed with the overlay such as the zebra mark 152, the white balance can be easily and accurately set.

As shown in FIG. 6, it is also possible to specify an image position at which white balance is to be obtained by using the cross button 56. When the operator operates the cross button 56, the pointer (cursor) 162 on the screen moves. The pointer 162 is moved to a desired image position, the gain of each color multiplier in the white balance adjustment circuit 96 is adjusted so that the white balance is adjusted to the specified position, and white balance correction is performed. In addition, it is also possible to apply a touch panel instead of or in combination with the cross button 56.

The setting of the white balance is performed before taking in (recording) an image for recording, such as during display of a through image, and the photographing operation is performed after the desired white balance is set.

In the above description, an example has been described in which the present invention is applied to a digital camera for recording a still image. However, the scope of the present invention is not limited to the above-described embodiment, and a digital camera and a video camera capable of recording a moving image. Widely applicable to electronic cameras such as.

[0055]

As described above, according to the imaging apparatus of the present invention, a gray vicinity portion in a photographed image is detected, and a predetermined fixed display pattern is distinguished from the gray vicinity portion with respect to other regions. Since the overlay display is performed, the photographer can easily grasp the state of the white balance. In particular, a GUI is displayed so that the operator can easily specify the white balance correction amount, and the GUI is displayed so that the achromatic subject in the image has the fixed display pattern.
Since the white balance can be set using I, the white balance can be set easily and accurately.

According to another aspect of the present invention, the photographer arbitrarily designates an image position at which the photographer intends to obtain a white balance, and automatically adjusts the white balance so that the designated image position becomes gray. By performing such control, a desired white balance can be easily set.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a digital camera according to an embodiment of the present invention.

FIG. 2 is a rear view of the digital camera shown in FIG. 1;

FIG. 3 is a block diagram showing the configuration of the digital camera of the present embodiment

FIG. 4 is a diagram showing an example in which a portion near gray is overlaid with a fixed pattern;

FIG. 5 is a view showing an example of a screen on which a GUI for designating a white balance correction amount is displayed.

FIG. 6 is a diagram illustrating an example of a screen in which an image position to be adjusted for white balance can be arbitrarily designated;

[Explanation of symbols]

Reference numeral 10: camera (imaging device), 50: liquid crystal monitor (image display means), 56: cross button (image position designation means), 7
8: CCD (imaging means), 82: CDS circuit (signal processing means), 84: A / D converter (signal processing means), 90:
CPU (gray area extraction means, display control means, control means), 94: signal processing section (signal processing means), 96: white balance adjustment circuit, 152: zebra mark (predetermined display pattern), 160: GUI

Claims (4)

[Claims] An imaging unit configured to convert an optical image into an electric signal and output an image signal indicating a subject image; a signal processing unit configured to process an image signal obtained by the imaging unit and convert the image signal into electronic image data; Image display means for displaying an image based on the electronic image data; a white balance adjustment circuit for adjusting a gain of a color signal of the image obtained through the imaging means; and a color adjustment of the image obtained through the imaging means. Gray area extracting means for detecting the degree and extracting an image part showing a saturation smaller than a preset threshold value; and an image part near achromatic color extracted by the gray area extracting means is predetermined. A display control means for controlling display contents of the image display means so as to perform display distinguished from other areas using a predetermined display pattern. 2. The imaging apparatus according to claim 1, further comprising a unit that allows an operator to specify the threshold value. 3. The image display means according to claim 1, wherein the image display means includes a correction amount designation G for the operator to designate a correction amount of the white balance in the white balance adjustment circuit.
The imaging apparatus according to claim 1, wherein a UI (graphical user interface) is displayed. 4. An imaging unit that converts an optical image into an electric signal and outputs an image signal indicating a subject image, a signal processing unit that processes an image signal obtained by the imaging unit and converts the image signal into electronic image data, An image display unit that displays an image based on the electronic image data; a white balance adjustment circuit that adjusts a gain of a color signal of the image acquired via the imaging unit; and an image displayed on the image display unit. Image position specifying means for the operator to specify an image position to be white-balanced, and control means for controlling the white balance adjustment circuit so that the position specified by the image position specifying means is achromatic. An imaging device comprising: