JPS6158393A - Color image pick up device - Google Patents

Abstract

PURPOSE:To reduce the number of necessary color temperature conversion filters and reduce a size of a color image pick up device by correcting the deterioration in color reproducibility owing to a color temperature change of an illumination light source electrically. CONSTITUTION:First and second color difference signal B-Y, R-Y are outputted by a photograph component 41, and a modulation component is separated in a BPF 52 and a color difference signal 42 is remodulated by a wave detector 53 to add to a white balance circuit 55. The reduced output component of a element 41 is taken out in a LPF 54 and added to a signal 42 through the circuit 55 and a color difference signal 53 is added to a synchronized circuit 56. The circuit 56 delays any of two color difference signals outputted alternately from the circuit 55 each scanning line by 1H. so that first and second color difference signals 44, 45 can be obtained at the same time. The scale of, these signals 44, 45 are corrected by gain control circuits 57, 58 individually. The circuits 57, 58 are controlled by the change of color temperature from a color temperature detecting circuit 20. A carrier from a terminal 29 and outputs from the circuits 57, 58 are added to a modulator 63 to reduce the necessary color temperature conversion filter.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a power-2 imaging device, and particularly to a color imaging device capable of correcting deterioration in color reproducibility due to differences in illumination light sources.

(Prior art and its problems) In a color imaging device using one solid-state imaging device such as a COD, a signal representing brightness and multiple signals representing color information are obtained from the output signal of a single solid-state imaging device. It is composed of The signal representing color information is obtained as a difference signal or a sum signal of two color signals, and from this, two signals necessary to form a composite color video signal are obtained.
Two color difference signals are obtained. For example, Tsukine et al.'s Telescope Society Technical Report March 1982 VOL6. NO45
゜In the paper published on pages 23 to 28 entitled "Color image evaluation of field readout type COD camera", it is shown in Figure 4 that if 几 is red, G is green, and B is the back signal component, A color imaging device that sequentially extracts two color difference signals, 2R-G from the n-th line and 28-G from the n+1-th line, using an array of color filters, and synchronizes them by delaying one of them by IH. It is shown.

In such a color imaging device, the ratio of R, G, and H signal components included in the color difference signal is determined by the spectral characteristics of the color filter on the solid-state imaging device and the color temperature of the illumination light source.几 contained in the color difference signal,
Since the ratio of G and B signal components represents the overall imaging characteristics, if the spectral characteristics of the color filter are set to obtain the best color reproducibility under one standard illumination light source,
Color reproducibility deteriorates under illumination light sources with other color temperatures.

In order to prevent this deterioration of color reproducibility, conventional color imaging devices have installed a color temperature conversion filter in the optical system. However, in reality, the illumination light source is has a very wide range of color temperatures, from below 0 to over 10,000, such as outdoors under clear skies.Therefore, in order to convert these to the color temperature of a standard illumination light source with less error, different optical systems are used. It is not practical because it requires a large number of characteristic color temperature conversion filters, and conversely, reducing the number of color temperature conversion filters to improve practicality has the disadvantage of deteriorating color reproducibility. A color imaging device capable of eliminating the drawbacks of the conventional color imaging device has been proposed in Japanese Patent Application No. 59-111329 (filed on 59/5/31) by the same applicant as the present invention. In this color imaging device, two
By correcting the magnitude of the two color difference signals, deterioration in color reproducibility due to changes in color temperature of the illumination light source is corrected.

FIG. 5 is an embodiment of the invention, and FIG. 6 is a diagram showing the amount of correction of the magnitude of two color difference signals according to the color temperature of the illumination light source in the embodiment.

In FIG. 5, the 0-band filter 52 includes a built-in color filter in which the first and second color difference signals 44 and 45 correspond to the BY signal and the RY signal, respectively. The output signal of the image sensor 41 is supplied,
The modulation components contained in this output signal are separated and extracted. The separated modulation components are detected by a detector 53 and a color difference signal 4 is generated.
The low-pass filter 54 demodulates the low-pass filter 54 to extract the low-pass components of the output signal of the image sensor 41. The white balance circuit 55 adds and subtracts the output signal of the low-pass filter 54 to the demodulated color difference signal 42, and adjusts the color difference signal 43 to be zero when an achromatic subject is imaged to achieve white balance. . The synchronization circuit 56 delays one of the two color difference signals alternately obtained from the white balance circuit 55 for each scanning line, and synchronizes it so that the first and second color difference signals 44 and 45 are obtained at the same time. The zero gain control circuits 57 and 58 independently correct the magnitudes of the two color difference signals 44 and 45 obtained from the synchronization circuit 56.

The subcarrier input from terminal 59 is directly transmitted to modulator 6
3 and is supplied to a modulator 63 after being phase-shifted in a phase shift circuit 60 to the phase required to create a modulated chroma signal together with the directly supplied subcarriers. In modulator 63, the two subcarriers are modulated by two magnitude-corrected color difference signals obtained from gain control circuits 57 and 58, respectively, to form a modulated chroma signal. The modulated chroma signal outputted by the modulator 63 is
The output signal of the imaging gR element 41 is added to the luminance signal obtained through the low-pass filter 65 and the process circuit 66 in an adder 67, and a composite color video signal is obtained at the terminal 68. is incident and decomposed into three primary color elements, and the color temperature is detected from the size of each of the three primary color elements.The calculation circuit 49 determines the amount of correction according to the detected color temperature of the illumination light source, and the gain control circuit 57
and 58 to correct the magnitudes of the first and second color difference signals.

FIG. 6 is a diagram showing the relationship between the color temperature of the illumination light source detected by the color temperature detection circuit 64 of FIG. 5 and the amount of correction supplied to the gain control circuits 57 and 58. As the color temperature of the illumination light source increases, the back component in the illumination light becomes larger and the red component becomes smaller. Therefore, the correction amount for the first color difference signal corresponding to the B-Y signal should be a small value. The correction amount for the second color difference signal corresponding to the signal becomes a large value.

There are many natural and artificial sources of illumination, such as sunlight and incandescent light bulbs, which have spectral characteristics close to blackbody radiation. In this case, if the correction amount shown in Figure 6 is set for an illumination light source with spectral characteristics close to blackbody radiation, it is possible to almost eliminate deterioration in color reproducibility due to color temperature changes of many illumination light sources. I can do it.

However, fluorescent lamps are one of the many illumination light sources that currently exist and have spectral characteristics different from those of blackbody radiation. Under an illumination light source with spectral characteristics different from blackbody radiation, such as a fluorescent lamp, if the correction amount is not set as described above, color reproducibility will be slightly degraded. This is because the ratio of red and blue components to green components is small even when compared to black body radiation whose color temperature has the closest spectral characteristics to fluorescent lamps, and therefore the current G This is because the ratio of each signal component is different between a fluorescent lamp and a black body radiation having the above color temperature. According to the present invention, the output signal of the image sensor is The luminance signal from B
A first color difference signal corresponding to the -Y signal and a second color difference signal corresponding to the -Y signal are formed, and a composite color video signal is synthesized from the luminance signal and the first and second color difference signals. In a color imaging device, first and second correction amounts are generated for the magnitudes of the first and second color difference signals, respectively, in accordance with the color temperature of an illumination light source having spectral characteristics close to those of blackbody radiation. means for generating third and fourth correction amounts for the magnitudes of the first and second color difference signals, respectively, in accordance with the color temperature of the irradiation light source having spectral characteristics different from blackbody radiation; and means for correcting the magnitudes of the first and second color difference signals by selecting one of the combination of the second correction amount and the combination of the third and fourth correction amounts. An imaging device is obtained.

(Detailed Description of Configuration) The present invention solves the drawbacks of conventional devices by adopting the above-described configuration. First, by electrically correcting deterioration in color reproducibility due to changes in color saturation of the illumination light source, the number of required color temperature conversion filters was reduced, resulting in a compact and practical device. Next, when the illumination light source has spectral characteristics close to blackbody radiation, there is a means for correcting the magnitude of the two color difference signals according to the color temperature of the illumination light source, and when the illumination light source has spectral characteristics different from blackbody radiation, such as a fluorescent lamp. In the case of characteristics, by providing means for correcting the magnitudes of the two color difference signals to predetermined magnitudes, deterioration in color reproducibility is almost eliminated for many illumination light sources.

(Embodiment 1) FIG. 2 is a block diagram showing the configuration of a first embodiment of a color imaging device according to the present invention.

In FIG. 2, the 0-band filter 52 includes a built-in color filter in which the first and second color difference signals 44 and 45 correspond to the BY signal and the B-Y signal, respectively. The output signal of the image sensor 41 is supplied,
The modulation components contained in this output signal are separated and extracted. The separated modulation components are detected by a detector 3 and a color difference signal 42 is generated.
is demodulated. The low-pass filter 54 extracts low-pass components of the output signal of the image sensor 41. The white balance circuit 55 adds and subtracts the output signal of the low-pass filter 54 to the demodulated color difference signal 42, and adjusts the color difference signal 43 to be zero when an achromatic subject is imaged to achieve white balance. ◎The synchronization circuit 56 delays one of the two color difference signals obtained alternately for each scanning line from the white balance circuit 55 by 1H, and synchronizes it so that the first and second color difference signals 44 and 45 are obtained at the same time. do. The gain control circuits 57 and 58 process the two color difference signals 44 and 4 obtained from the synchronization circuit 56.
5 are each corrected independently.

The subcarrier input from terminal 59 is directly transmitted to modulator 6
3 and L-, which together with the directly supplied subcarriers are phase shifted in a phase shift circuit 60 to the phase required to create a modulated chroma signal and then supplied to a modulator 63. In modulator 63, the two subcarriers are modulated by two magnitude-corrected color difference signals obtained from gain control circuits 57 and 58, respectively, to form a modulated chroma signal. The modulated chroma signal outputted from the modulator 63 is obtained by passing the output signal of the image sensor 41 through a low-pass filter 65 and a process circuit 66, and combining it with the obtained chroma signal and an adder 67.
A composite color video signal is obtained at terminal 68.

Illumination light is incident on the color temperature detection circuit 20 and is separated into three primary color lights, and the color temperature is determined from the ratio of each of the three primary color lights. The signal indicating the determined color temperature is given to the calculation circuit 49, which calculates the amount of correction for the two color difference signals shown in FIG. If the ratio is not close to the blackbody radiation of either color temperature, the control signal 21 is applied to the switch 23. If the switch 23 is connected to A 11111, the control signal 21 is applied to the switches 25 and 26. fixed value circuit 27.
The predetermined correction amounts given by the above are given to gain control circuits 57 and 58, respectively. When the switch 23 is connected to the M side, the warning light 22 is turned on to notify the user, and the control signal 21 is given to the switches 25 and 26 only when the user turns on the switch 24.

In the color temperature detection circuit 20, when the ratio of each of the three primary color lights is close to the black body radiation of any color temperature and when the switch 24 is not turned on, the control signal is not given to the switches 25 and 26. Switches 25 and 26 are connected to the opposite side, and the calculation circuit 59 provides the correction amount to gain control circuits 57 and 58.

The combination of two predetermined correction amounts given to the fixed value circuit 27 and the gain control circuits 57 and 58 is determined by the calculation circuit 4.
This is different from any of the combinations of the two correction amounts given by No. 9.

(Example 2) FIG. 3 is a block diagram showing the configuration of the second embodiment.

In the second embodiment, except for the color temperature detection circuit 20, calculation circuit 59, warning lamp 22, and switches 23 to 26 shown in FIG.
Same configuration as the first embodiment.

It's in action.

The color temperature detection circuits 30 and 31 detect the color temperature of the illumination light from the ratio of the evening and green components and the ratio of the red and green components in the illumination light, respectively, and a signal indicating each chromaticity is sent to the calculation circuit 32.
and 33.

Calculation circuits 32 and 33 calculate correction amounts for the first and second color difference signals shown in FIG. 6, respectively. The switches 34 and 35 are operated by the user, and when connected to the - side, the correction amount given by the calculation circuits 32 and 33 is selected, and when connected to the F side, the correction amount given by the calculation circuits 32 and 33 is selected, and when connected to the F side, the correction amount is selected as shown in FIG. A predetermined correction amount provided by fixed value circuit 27 is selected and provided to gain control circuits 57 and 58.

(Embodiment 3) FIG. 1 is a block diagram showing the configuration of a third embodiment.
The configuration other than 1 is the same as the second embodiment.

It is an action.

The color temperature detection circuits 10 and 11 include a white balance circuit 5.
5, signals 12 and 13 indicating the magnitude of the output signal of the low-pass filter 54 which is added to or subtracted from the color difference signal 42 corresponding to the first and second color difference signals 44, 45 are provided;
The color temperature of the illumination light is detected from each; a signal indicating the detected color temperature is given to calculation circuits 32 and 33.

Calculation circuits 32 and 33. Fixed value circuit 27, switch 3
The operations of 4 and 35 are the same as in the second embodiment. (Effects of the Invention) As explained above, according to the present invention, even when the spectral characteristics are different from black body radiation, such as in a fluorescent lamp, the color A compact and practical color imaging device with almost no poor reproducibility [hi] can be obtained.Brief explanation of the mouth surface FIGS. 1 to 3 show the configuration of an embodiment of the color imaging device of the present invention. FIG. 4 is a block diagram showing the arrangement of color filters, FIG. 5 is a block diagram showing the configuration of a color imaging device previously proposed by the applicant, and FIG. 6 is a correction amount of illumination light source chromaticity and color difference signal. In each figure, 41 is an image sensor, 52 is a 'l\ band filter, 53 is a detector, 54.65 is a low-pass filter, 55 is a white balance circuit, 56 is a synchronization circuit, and 57 and 58 is a gain control circuit, 60 is a phase shift circuit, 63 is a modulator, 66 is a process circuit, 67 is an adder, 10.11, 20, 30,
31.64 is a color temperature detection circuit, 32, 33.49 is a calculation circuit, 23~26°34.35 is a switch, 27 is a fixed value circuit, 22 is a warning light port

Claims (1)

[Claims] A first color difference signal corresponding to the luminance signal and the B-Y signal and a second color difference signal corresponding to the R-Y signal are formed from the output signal of the image sensor, and the luminance signal and the first and second color difference signals are formed.
In a color imaging device in which a composite color video signal is synthesized from color difference signals of and means for generating first and second correction amounts for the magnitudes of the first and second color difference signals, respectively, in accordance with the color temperature of the irradiation light source having spectral characteristics different from the black body radiation. means for generating a correction amount, a combination of the first and second correction amounts, and a third correction amount;
and means for selecting one of a fourth combination of correction amounts to correct the magnitudes of the first and second color difference signals.