JPH11187412A - Image-pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-pickup device or the like that is not affected by a color of an object or the like and the correction value of white balance of which can be changed, depending on a color temperature of a light source. SOLUTION: This image-pickup device having a means that applies white balance correction to 3 primary color signals is provided with a color temperature input section 10, that sets color temperature information of a light source emitting an object and with a white balance correction circuit 5, that obtains a correction value of white balance correction based on the color temperature information set by the color temperature input section 10 and conducts correction control based on the correction value, and the white balance correction circuit 5 controls the gain of a gain control circuit 7 according to the correction value. Furthermore, the device is provided with a memory 6 that stores plural color temperature information in cross reference with plural light sources and the color temperature input section 10 can call any desired one from among the plural color temperature information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging device such as a video camera or a digital camera, and more particularly to an imaging device having a white balance correction function.

[0002]

2. Description of the Related Art For example, when a white subject is photographed by an imaging device such as a video camera under daylight in the daytime (substantially regarded as white light), a signal level R of three primary color signals output from the subject is obtained. (Red), G (Green), B
The relationship of R = G = B is established between (Blue). However, when a white object is similarly photographed under a light source such as a fluorescent lamp or a halogen lamp, the balance (white balance) of the three primary color signals is lost, and the photographed image signal is not corrected. If output as it is, the image will look strange to human eyes. For this reason, various techniques related to white balance correction have conventionally been provided. For example, Japanese Patent Laid-Open No. 1-2219
In the electronic still camera disclosed in Japanese Unexamined Patent Publication No. 94-94, a color temperature is detected by light from an imaging screen or its surroundings, and a video signal obtained by color-correcting a primary color signal output from an imaging device with a correction value corresponding to the color temperature. In an electronic still camera configured to perform image recording by using the above-described method, not only image recording in which color correction is performed using the above-described correction value but also image recording of a plurality of images by performing color correction using another correction value in which the above-described correction value is increased or decreased The white balance continuously variable photographing mode is performed. Further, in the image pickup apparatus disclosed in Japanese Patent Application Laid-Open No. 2-213292, a correction value when white balance correction is automatically performed can be manually corrected.
In the image recording apparatus disclosed in Japanese Patent Application Laid-Open No. 6-90464, when a strobe is used as auxiliary light when capturing a still image in the still shooting mode, the white balance set value immediately before the strobe emission is stored in the storage unit. The flash memory is forcibly set to a predetermined value corresponding to the color temperature of the flash, and the flash is fired. After the still shooting using the flash, the white balance setting stored in the storage unit is stored. It has a configuration to return to the value. Further, the imaging apparatus disclosed in Japanese Patent Application Laid-Open No. 7-23400 is provided with a detector for detecting the brightness of a subject, and by changing the white balance correction range according to the output of the detector, a low color temperature is obtained. It is trying to achieve a white balance close to the human sense for a subject under a light source.

[0003]

However, in the above-mentioned prior art, the light amount from the entire subject or the light amount from a wide range including the surrounding area is detected and converted into the color temperature of the light source. For the former, for example, if a thin blue wall is used for the background, blue will dominate and the thin blue wall will be corrected to white, and the latter will not be able to be taken into the color temperature sensor well However, there is a disadvantage that it is vulnerable to backlight. In order to solve such a defect, the related art disclosed in Japanese Patent Application Laid-Open No. 1-221994 records a plurality of images by changing the correction value. The method of recording increases operating costs. An object of the present invention is to solve the above-described problems of the related art, and to provide an imaging apparatus and the like that can change a correction value of white balance correction depending on the color temperature of a light source without being affected by an object color (color of an object). To provide.

[0004]

According to the first aspect of the present invention, a light source for illuminating a subject is provided in an imaging apparatus having a means for performing white balance correction on three primary color signals. Color temperature setting means for setting the color temperature information, and white balance correction means for performing white balance correction based on the color temperature information set by the color temperature setting means. According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a color temperature storage unit for storing a plurality of pieces of color temperature information in association with a plurality of light sources. According to a third aspect of the present invention, in the first aspect of the present invention, the correction range setting means for setting an effective correction range of the white balance correction means, and whether the balance of the input three primary color signals is within the effective correction range. And a white balance correction unit configured to perform white balance correction only when the validity determination unit determines that the balance is within the valid correction range.

[0005]

According to the first aspect of the present invention, white balance correction is performed based on color temperature information set using a keyboard or the like. According to the second aspect of the invention, a plurality of pieces of color temperature information associated with a plurality of light sources can be stored. According to the third aspect of the invention, white balance correction is performed only when the balance of the input three primary color signals is within the effective correction range.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an imaging apparatus according to an embodiment of the present invention. As shown in the figure, the imaging apparatus of this embodiment includes a lens 1, a solid-state imaging device (for example, a CCD) 2 for converting a subject image projected through the lens 1 into an electric signal, and an output from the solid-state imaging device 2. Sample-and-hold circuit 3 that samples and holds each pixel and amplifies it to an appropriate level, a color separation circuit 4 that separates an input signal into three primary color signals of red (R), green (G), and blue (B). A white balance correction circuit 5 for performing white balance correction control for the three primary color signals, a memory 6 for setting color temperature information of a light source, etc., a gain control circuit 7 for controlling gain, a luminance signal Y from R, G, and B signals. And a luminance / color difference signal generation circuit 8 for generating color difference signals (RY) and (BY), an encoder 9 for converting the luminance / color difference signals into a video signal V, and a color temperature for inputting a color temperature of a light source and the like. Input unit 10, and an input color temperature and the like correction coefficient conversion unit 11 for converting the white balance correction coefficient G / R and G / B.

As shown in FIG. 2, the color temperature input section 10 includes a display section 21, numeric keys 22, input keys 23,
An automatic white balance setting key 24, a manual white balance setting key 25, a memory recall setting key 26, a range setting key 27, and the like are provided. Hereinafter, FIGS. 1 and 2
The operation of this embodiment will be described with reference to FIG. First, regarding the operation of the color temperature input unit 10, when performing automatic white balance correction, the automatic white balance setting key 24 is used.
push. Then, the color temperature input unit 10 recognizes this and causes the display unit 21 to display "AUTO" (FIG. 3A).
reference). Further, the color temperature input unit 10 gives an instruction to the white balance correction circuit 5 indicating that the white balance correction is automatic white balance correction. When setting the color temperature of the light source, the color temperature of the light source known in advance by measurement with a color thermometer or the like is input using the ten keys 22 and the input key 23 is pressed. For example, if the color temperature of the light source is 3200K, 3200
Is input and the input key 23 is pressed, the color temperature input unit 10 recognizes this and displays “3200K” on the display unit 21 (see FIG. 3 (2)). Similarly, if the color temperature of the light source is 5800K, input 5800 and press the input key 23, and "5800K" is displayed on the display unit 21 (see FIG. 3 (3)).

The input color temperature is converted by a correction coefficient converter 11 into white balance correction coefficients G / R and G / B. When the color temperature is determined, the spectral energy ratios G / R and G / B of the light source are automatically determined. For example, the correction coefficient conversion unit 11 includes a conversion table as shown in FIG.
The spectral energy ratio is determined from the input color temperature. Thus, the white balance correction coefficient output from the correction coefficient conversion unit 11 is given to the white balance correction circuit 5. If the memory call setting key 26 is pressed at this time, the color temperature input unit 10 recognizes this and stores the color temperature information of the light source input at this time in the memory 6. To recall the stored color temperature of the light source, the memory recall setting key 26 is pressed, and the color temperature recalled from the memory 6 is converted by the correction coefficient conversion unit 11 into white balance correction coefficients G / R and G / R. B and is given to the white balance correction circuit 5. By repeating the color temperature setting (storage) operation a plurality of times, for example, as shown in FIG. 5, it is possible to store a plurality of color temperatures corresponding to a plurality of light sources. When the memory recall setting key 26 is pressed again as described above while a plurality of data are stored, the color temperature input unit 10 recognizes this and displays as shown in FIG. 3 (4). Therefore, for example, when it is desired to call up the third stored color temperature information, the color temperature input unit 10 recognizes this by inputting “3” using the numeric keypad 22 and recognizes the third stored color temperature information. Call.

To set the range in which the white balance is effective in the automatic white balance mode, after pressing the range setting key 27, first enter the lower limit color temperature to be effective, and then, enter the upper limit color temperature. Enter In this way, the color temperature input unit 10 acquires the two inputted temperatures, displays them as shown in FIG. 3 (6), and stores the two temperatures in a predetermined area in the memory 6. Next, the automatic white balance correction operation will be described.
First, input light from a subject enters the solid-state imaging device 2 via the lens 1 and is converted into an electric signal. The electric signal is sampled and held for each pixel in the sample and hold circuit 3 and amplified to an appropriate level. Then, the signal is separated into three primary color signals of red (R), green (G), and blue (B) in the color separation circuit 4. When each of the three primary color signals is input to the white balance correction circuit 5, if the white balance correction circuit 5 is set to the automatic white balance correction mode by an instruction from the color temperature input unit 10, the white balance correction circuit 5 Calculates the average value (cumulative value) of each of the input three primary color signals, and calculates the spectral energy ratios G / R and G / B according to the average values. Subsequently, the white balance correction circuit 5 controls the R signal gain control circuit 71 and the B signal gain control circuit 72 based on the calculated spectral energy ratios G / R and G / B so that R = G = B. That is, when the R spectral energy or the B spectral energy obtained from the average value is smaller than the G spectral energy, the R signal gain control circuit 7
The 1 and B signal gain control circuit 72 operates to increase the gain.

Thereafter, the G signal and the gain-controlled R,
The B signal is output from the luminance / color difference signal generation circuit 8 to the luminance signal Y.
And two color difference signals RY and BY, and further converted into a video signal V by the encoder 9 and output. On the other hand, when each of the three primary color signals is input to the white balance correction circuit 5 and the manual white balance correction mode is set in the white balance correction circuit 5 by an instruction from the color temperature input unit 10, the white balance correction is performed. Since the coefficients G / R and G / B are given to the white balance correction circuit 5 as described above, the white balance correction circuit 5 performs R = G = B based on the white balance correction coefficients G / R and G / B. R signal gain control circuit 71 and B signal gain control circuit 72
Control. That is, when the R spectral energy and the B spectral energy of the light source are smaller than the G spectral energy, the operation of increasing the gains of the R signal gain control circuit 71 and the B signal gain control circuit 72 is performed accordingly. When the lower limit color temperature and the upper limit color temperature are set as the color temperature ranges in which white balance correction is effective,
G corresponding to the lower limit temperature in the correction coefficient conversion unit 11
/ R minimum value ((G / R) min), R / B minimum value ((R / B) min), and G / R maximum value ((G / R) max corresponding to the above upper limit color temperature) ), The maximum value of R / B ((R / B) max) is calculated and given to the white balance correction circuit 5. In such a case, the white balance correction circuit 5 calculates the spectral energy ratios G / R and G / B based on the average value (cumulative value) obtained for each of the three primary color signals input from the color separation circuit 4. Are (G / R) min to (G / R) max and (R /
B) It is determined whether or not the range is from min to (R / B) max. Then, if within the range, R = G = B so that R = G = B.
The signal gain control circuit 71 and the B signal gain control circuit 72 are controlled. If it is out of the range, the white balance correction is not performed, and the signal output from the color separation circuit 4 is directly input to the luminance / color difference signal generation circuit 8. In claim 1, the color temperature setting means means the memory 6, the color temperature input section 10 and the correction coefficient conversion section 11, and the white balance correction means is the white balance correction circuit 5, the gain control circuit 7, and the luminance / color difference signal. Means the generation circuit 8. Also,
In claim 2, the color temperature storage means means the memory 6, and in claim 3, the correction range setting means is the color temperature input section 10 and the correction counting section 11, the validity determination means is the white balance correction circuit 5, The white balance correction means means the white balance correction circuit 5, the gain control circuit 7, and the luminance / color difference signal generation circuit 8, respectively.

[0011]

As described above, according to the present invention,
According to the first aspect of the present invention, the white balance is corrected based on the color temperature information set using a keyboard or the like, so that the white balance based on the color temperature of the light source is not affected by the object color (color of the subject). Balance correction can be performed, and therefore, an output image without a sense of incongruity even when the light source changes can be obtained. According to the second aspect of the present invention, a plurality of color temperature information associated with a plurality of light sources can be stored, so that the operation of designating the color temperature can be easily performed in the first aspect of the present invention. Become. According to the third aspect of the present invention, the white balance correction can be performed only when the balance of the input three primary color signals is within the effective correction range. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a main part of an imaging apparatus according to an embodiment of the present invention.

FIG. 3 is another explanatory diagram of a main part of the imaging apparatus according to the embodiment of the present invention.

FIG. 4 is a data configuration diagram of a main part of an imaging apparatus according to an embodiment of the present invention.

FIG. 5 is another data configuration diagram of a main part of the imaging apparatus according to the embodiment of the present invention.

[Explanation of symbols]

1 lens, 2 solid-state imaging device, 4 color separation circuit, 5
White balance correction circuit, 6 memory, 7 gain control circuit, 10 color temperature input section, 11 correction coefficient conversion section, 2
1 display unit, 22 numeric keys, 24 automatic white balance setting keys, 25 manual white balance setting keys,
26 memory setting key, 27 range setting key,
71 R signal gain control circuit, 72 B signal gain control circuit

Claims (3)

[Claims] 1. An image pickup apparatus comprising: means for performing white balance correction on three primary color signals; a color temperature setting means for setting color temperature information of a light source for irradiating a subject; And a white balance correction unit for performing white balance correction based on the color temperature information. 2. The imaging apparatus according to claim 1, further comprising a color temperature storage unit that stores a plurality of pieces of color temperature information in association with a plurality of light sources. 3. The image pickup apparatus according to claim 1, wherein a correction range setting means for setting an effective correction range of the white balance correction means, and whether or not the balance of the input three primary color signals is within the effective correction range. An imaging apparatus, comprising: validity determining means; wherein the white balance correcting means is configured to perform white balance correction only when the validity determining means determines that the balance is within the valid correction range.