JPH03128591A - Color video camera - Google Patents

Abstract

PURPOSE:To prevent red color from looking sinking even under a fluorescent lamp or the like by detecting the AC component included in a light source by an AC component detecting circuit and selecting a control signal obtained by linear conversion of the output of a dividing circuit or an optimum control signal from a table converter in accordance with the magnitude of the detected AC component to control a luminance signal generating matrix circuit. CONSTITUTION:When the AC component which is included in the light source which is detected by an AC component detecting circuit 20 is large, a selecting circuit 22 selects the output of a table converter 21. The light source whose AC component is detected is a discharging lamp mainly including a white fluorescent lamp. The table converter 21 outputs the control signal of an R channel gain control circuit 8 for luminance signal generation most suitable for the classification of the discharging lamp and that of a B channel gain control circuit 9 for luminance signal generation. Dividing circuits 16 and 17, the AC component detecting circuit 20, the table converter 21, linear conversion circuits 18 and 19, and the selecting circuit 22 are realized with either of hardware and software.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color video camera with improved color reproducibility.

[Conventional technology]

FIG. 2 is a block diagram showing a conventional color video camera disclosed, for example, in Publication No. 1@41-16011. In the figure, 1 is a lens through which light from a subject (not shown) passes. , 2 is an image sensor that images the subject through the lens 1, 3 is a color separation circuit that separates the broadband luminance signal yo and each color signal R0G, B from the output signal of the image sensor 2, 4
is an R channel gain control circuit for gain controlling the color signal R;
5 is a B-channel gain control circuit that controls the gain of the color signal B; 6 is a gain-controlled color difference matrix circuit that generates color difference signals R-Y and B-Y based on the R, B and G signals; and 1 A luminance signal generation matrix circuit that generates a luminance signal Y based on a wideband luminance signal yo and color signals R and B.
A luminance signal generation R channel gain control circuit 8 that controls the gain of the signal and a luminance signal generation B circuit that controls the gain of the B signal.
It is composed of a channel gain control circuit 9 and an adder 10 whose gain is controlled and which adds the nine R and B signals and the broadband luminance signal yo. 11 is a luminance signal Y and a color difference signal RY.

This is an encoder circuit that synthesizes the signals B and Y to form a color television signal of a predetermined format and outputs it to the output terminal 12.

13.14.15 is the R component contained in the light from the subject,
The R sensor, G sensor, and B sensor are composed of photoelectric conversion elements that detect the G component and the B component, respectively. 16 is the ratio R8 of the output R8 of the R sensor 13 and the output Gs of the G sensor 14
/G8=vR is determined, and the above R channel gain control circuit 4
17 is a division circuit that calculates the ratio G s/B, = V B, between the GS and the output Bs of the B sensor, and combines it with the control signal of the B channel gain control circuit 50. 18 is a linear conversion circuit that linearly converts the vR to form a control signal for the R channel gain control circuit 80 for generating the luminance signal, and 19 linearly converts the VB to control the B channel gain control circuit 9 for generating the luminance signal. This is a linear conversion circuit that converts signals.

Next, the operation will be explained.

A light image incident from a lens 1 is photoelectrically converted by an image sensor 2, and separated by a color separation circuit 3 into a broadband luminance signal yo and R, G, and B color signals.

Next, the B channel gain control circuit 4 controls the gain of the R signal, and the B channel gain control circuit 5 controls the gain of the B signal, thereby performing white balance adjustment.

On the other hand, R sensor 13. G cent t14. The B sensor 15 is
Generates output proportional to the R, G, and B components of the incident light. 1. Each output value is RB eGB eBB
Then, the division circuit 16 outputs a ratio G57Rs (control signal VB) between the G component and the R component that does not depend on the amount of incident light. Similarly, the division circuit 17 outputs the ratio BS/Gs (control signal VB) between the B component and the G component. Here, the gain of the B channel gain control circuit 4 increases as the control signal vR increases, and the gain of the B channel gain control circuit 5 decreases as the control signal VB increases.

Furthermore, when the color temperature of the light source that illuminates the subject is low, that is, when the color temperature of the light source is high with respect to the G component, the R component is large and the B component is small. shows a lower value compared to Therefore, when the color temperature of the light source is low, the gain of the B channel gain control circuit 4 is small and the gain of the B channel gain control circuit 5 is large.

On the other hand, in the case of a light source with a high color temperature, that is, in the case of a light source with less R component and more B component than G component, the gain of the B channel gain control circuit 4 is large. The gain of circuit 5 becomes smaller.

As mentioned above, the R component and #G component are reflected in the light source.

In response to changes in the B component, the B channel gain control circuit 4
White balance adjustment is performed by automatically controlling the gain of the B channel gain control circuit 5 and the gain of the B channel gain control circuit 5.

Additionally, a broadband luminance signal y.

In order to correct the R component and B component contained in
9 and applied to the R channel gain control circuit 8 for generating a luminance signal and the B channel gain control circuit 9 for generating a luminance signal, respectively.

Accordingly, the R component and B component included in the wideband luminance signal yo
A luminance signal Y with corrected component ratios is generated. The R channel and B channel gain control circuits 8 and 9 are configured, for example, as four-quadrant multiplier circuits, and are capable of outputting positive phase or negative phase depending on the control signal applied thereto.

[Problems to be Solved by the Invention] Conventional color video cameras are configured as described above, so when the light source is a fluorescent lamp, for example, its spectral distribution characteristics are affected by the bright line spectrum, fluorescent material, etc. Since it is different from natural light, a control signal obtained by linearly converting the above VHsVB is used to generate a wideband luminance signal y.

If the ratio of R component and B component included in is corrected,
For example, there were issues such as red colors appearing sunken.

This invention was made in order to solve the above-mentioned problems, and the object is to obtain a color video camera in which, for example, red color does not appear subdued even under fluorescent light. .

[Means to solve the problem]

The color video camera according to the present invention detects an alternating current component contained in a light source using an alternating current component detection circuit, and generates a control signal obtained by linearly converting the output of a dividing circuit according to the magnitude of the alternating current component. Alternatively, the optimum control signal from the table converter is selected to control the luminance signal generation matrix circuit.

[Effect]

In the luminance signal generation matrix circuit of the present invention, when the AC component contained in the light source is large, a control signal obtained by table conversion of the output of the division circuit is added, and when the AC component is small, the output of the division circuit is added. A linearly transformed control signal is added.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, parts corresponding to those in FIG. 2 are denoted by the same reference numerals, and explanation thereof will be omitted.

In FIG. 1, 20 is included in the output G8 of the G sensor 14.
AC component detection circuit for detecting the magnitude of the AC component that is generated; 2
1 is a table converter that outputs an optimal control signal according to the division circuit 16 and 170 outputs vR and vB, and 22 is a selection circuit that outputs a control signal output from the linear conversion circuit 18 and 19 or output from the table converter 21. The control signal to be detected is selected according to the magnitude of the AC component detected by the AC component detection circuit 20, and the R channel gain control circuit for luminance signal generation a
and is supplied to the B channel gain control circuit 9 for generating a luminance signal.

Next, the operation will be explained.

The AC component detection circuit 20 detects the AC component of the amount of light contained in the light source, and if this AC component is small, the selection circuit 22 selects the output of the linear conversion circuit 18, 19,
This is a control signal for the R channel gain control circuit 8 for generating a luminance signal and the B channel gain control circuit 8 for generating a luminance signal.

If the AC component contained in the light source detected by the AC component detection circuit 20 is large, the selection circuit 22 selects the output of the table converter 21. The light source from which the alternating current component is detected is mainly a discharge lamp including a white fluorescent lamp. If there is a condition that the alternating current component is large, this discharge lamp is divided by the dividing circuit 16.
．． 17 output VB.

It is possible to classify them according to the size of vB.

The table converter 21 outputs a control signal for the R-channel gain control circuit 8 for m-degree signal generation and a control signal for the B-channel gain control circuit 90 for luminance signal generation, which are most suitable for the type of discharge lamp. This can eliminate the problem that, for example, when a red image is captured under a fluorescent light, the brightness level of the image decreases.

Note that the division circuit 16. ．． 17. AC component detection circuit 20 The table converter 21, linear conversion circuit N1.19, selection circuit 22, etc. may be realized by hardware or software. When realized by software, the linear conversion circuits 18 and 19 may be configured by table converters. In that case, it is necessary to provide two table converters, one that is selected when the alternating current component of the light source is above a certain level, and the other that is selected when it is below a certain level.

Further, the division circuits 16 and 17 may have an output based on a ratio of two input variables, and may be one that performs logarithmic transformation, for example.

〔Effect of the invention〕

As described above, according to the present invention, whether the light source illuminating the subject is a discharge lamp such as a white fluorescent lamp or not is determined based on the output of the AC component detection circuit, and the discharge lamp In this case, the table converter is configured to give a gain control signal for the luminance signal generation matrix circuit that is suitable for the type of discharge lamp, so even when capturing images with a camera under a discharge lamp, the table converter is configured to provide the gain control signal for each color. This has the effect of providing a brightness level.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a color video camera according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional color video camera. 2 is an image sensor, T is a luminance signal generation matrix circuit%13
is the R sensor, 14 is the G sensor, 15 is the B sensor, 16.
17 is a division circuit, 18 and 19 are linear conversion circuits, 20 is an AC component detection circuit, 21 is a table converter, and 22 is a selection circuit. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] at least two color sensors that detect mutually different colored lights, a division circuit that calculates the ratio of the outputs of the color sensors, and at least one
an AC component detection circuit that detects the magnitude of an AC component included in the output of the color sensor; a brightness signal generation matrix circuit that generates a brightness signal based on a color signal separated from the output of the image sensor; a table converter that outputs a control signal for controlling the color signal in the luminance signal generation matrix circuit according to the output of the division circuit; and a table converter that linearly converts the output of the division circuit to control the color signal in the luminance signal generation matrix circuit. a linear conversion circuit comprising a control signal for controlling the AC component, and a control signal output from the table converter or a control signal output from the linear conversion circuit depending on the magnitude of the AC component detected by the AC component detection circuit. and a selection circuit that selects and supplies the luminance signal to the luminance signal generation matrix circuit.