JP2674990B2 - Imaging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus having an image pickup device that converts an optical image into a plurality of color signals and extracts the signals. [Prior Art] In an imaging device that converts an optical image into electric signals of three primary colors, the amplification gain of each color signal system of an electronic circuit photoelectrically converted is adjusted according to the color temperature of a light source that illuminates a subject.
It is necessary to adjust the so-called white balance. Conventionally, the adjustment of the white balance has been treated mainly for the stationary light, but on the other hand, when using the flash light emitting device, the white balance is adjusted according to the color temperature of the light emission of the flash emitting device. There was only one that decided uniquely. [Problems to be Solved by the Invention] However, even when shooting is performed using a flash light emitting device, there are many cases in which the contribution from ambient light (ambient light) cannot be ignored as the ambient condition of the subject. In that case, a satisfactory image cannot be taken by the method of adjusting the white balance which is adjusted to only one of the ambient light and the flash light emission as in the conventional method. Therefore, an object of the present invention is to consider both the contribution of ambient light and the contribution of flash emission at the time of shooting,
An object of the present invention is to provide an image pickup device capable of obtaining a correct white balance by considering the respective color temperatures of flash light emission in combination. [Means for Solving Problems] In order to achieve such an object, in the present invention, the white balance is adjusted by, for example, values obtained by measuring the light amounts of flash light emission and ambient light from the surroundings other than that. To do. That is, the present invention is an image pickup apparatus in which an optical image is formed on the surface of an image pickup element, converted into a plurality of color signals and taken out, and a flashlight emitting means, and means for storing color temperature data for the flashlight emitting means. First detecting means for measuring the subject distance, calculating means for obtaining the irradiation intensity of the subject by calculating the subject distance and the light amount of the flash light emitting means for obtaining the illumination intensity of the subject, and measuring the subject brightness due to ambient light Second detecting means, a color measuring means for measuring a color temperature due to ambient light, an amplifying means for controlling the balance of color signals formed from the image sensor, and a measurement measured by the second detecting means. Value, the irradiation intensity obtained by the calculation means,
It is characterized in that it comprises a means for adjusting the white balance by controlling the amplification gain by the amplification means according to the color temperature value measured by the color measurement means and the color temperature data for the flash light emission means. [Operation] According to the present invention, when the contributions of both ambient light and flash light emission at the time of shooting cannot be ignored, it is possible to obtain a white balance in consideration of the respective color temperatures. EXAMPLES The present invention will be described below in detail with reference to the drawings. Here, an image pickup apparatus including a flash light emitting device of a constant light amount (known) and an automatic focusing member will be described as an example. FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention for that purpose. In the figure, 1 is an optical system for forming a subject image, 2a is a shutter, which has a built-in diaphragm. 2b is a driver (driving circuit) for the shutter 2a, 3 is an image sensor using, for example, a CCD, and converts an optical image of a subject into an electric signal, for example, red (R), blue (B), green (G) It is taken out as three primary color signals. Reference numerals 4 and 5 are variable gain amplifiers inserted in the electric signal circuits of the R and B primary colors, respectively. By balancing the gains of the above-described amplifiers with respect to the color temperature of the light source that illuminates the subject, correct color reproduction, that is, white balance can be obtained. 6 is a signal processing circuit, 7 is a recording circuit, 9 is an autofocus member corresponding to the first detecting means, 10 is a photometric circuit corresponding to the second detecting means, 11 is a colorimetric circuit for ambient light, 12 Is a flash light emitting device, 13 is a release switch, and 14 is an arithmetic control circuit corresponding to arithmetic means. The above is the configuration of the embodiment of the present invention, and its operation will be described below. When a power source (not shown) is turned on, the photometric circuit 10 and the colorimetric circuit 11 are activated to set the brightness Bv of the stationary illumination light and its color temperature (R; B; G = A _R1 : A _B1 : 1). The measurement is performed and the result is input to the arithmetic and control circuit 14. After that, when the release switch 13 is operated, the automatic focusing member 9 operates to adjust the optical system 1 for focusing, measure the distance D to the subject, and calculate the value. To enter. Assuming that the light quantity (GN ₀ ) of the flash light emitting device 12 is known, the diaphragm (FN ₀ ) at which proper exposure can be obtained is given by the following equation. FN ₀ = (GN ₀ ) / D (1) Then, the shutter / aperture 2a is driven by the driver 2b (1)
Information about the subject image taken out from the image sensor 3 (electrical signal) over the next one field period (or frame period) after the flash light emitting device 12 is caused to emit light by driving up to the diaphragm Read
The signal processing circuit 6 converts the signal into a signal form that can be recorded on the medium, and then the recording circuit 7 records the signal on the medium. Here, we will consider a little about the method of white balance. The intensity of light emitted from the flash device to the subject is (GN _o / D)
² and the ratio with the ambient light irradiation intensity Bv If k + 1 = 1 (3) and the white balance for the flash emission stored in the storage device is R: B: G = A _R2 : A _B2 : 1 (4), the amplification degree of the amplifiers 4 and 5 is A _R and A _B
By making the relation of A _R = kA _R1 + lA _R2 (5) A _B = kA _B1 + lA _B2 (6), a white balance can be obtained in which the contributions of ambient light and flash emission are considered. The values of k and l in the equations (5) and (6) can be set to the most appropriate values by including a correction term in the equation (2) in consideration of the characteristics of the image sensor. EFFECTS OF THE INVENTION As is clear from the above, according to the present invention, even when the contributions from both ambient light and flash light emission cannot be ignored, the measurement value measured by the second detecting means and the calculation By controlling the irradiation intensity obtained by the means, the value of the color temperature measured by the colorimetric means, and the amplification gain by the amplification means according to the color temperature data of the flashlight emitting means, the correct white balance is automatically obtained. You can make adjustments.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of one embodiment of the present invention. 1 ... Optical system, 2a ... Shutter, 2b ... Shutter drive circuit, 3 ... Imaging element, 4,5 ... Amplifier, 6 ... Signal processing circuit, 7 ... Recording circuit, 9 ... Auto focus member , 10 ... Photometric circuit, 11 ... Color measuring circuit, 12 ... Flash light emitting device, 13 ... Release switch, 14 ... Arithmetic control circuit.

Claims (1)

(57) [Claims] In an image pickup apparatus which forms an optical image on the surface of an image pickup device, converts it into a plurality of color signals and takes out the same, a flash light emitting means, a means for storing color temperature data of the flash light emitting means, and a subject distance measurement. First detecting means for calculating the illumination intensity of the subject, computing means for computing the subject distance and the light amount of the flash light emitting means to obtain the illumination intensity of the subject, and measuring the luminance of the subject by ambient light. 2 detecting means, a color measuring means for measuring the color temperature by the ambient light, an amplifying means for controlling the balance of color signals formed from the image pickup device, and a second detecting means. A measurement value, an irradiation intensity obtained by the calculation means, a color temperature value measured by the color measurement means, and the amplification means according to the color temperature data of the flash light emission means. The amplification gain control to an imaging apparatus, characterized in that it comprises a means for adjusting the white balance that.