JPH0244991A - Image picked up signal processor for color video camera - Google Patents

Abstract

PURPOSE:To improve a color reproducibility by applicably changing the mixture ratio of a color difference signal so that a good color reproducibility may be obtained in the memory color of a skin color and the like according to the kind of an illumination light. CONSTITUTION:When a discrimination signal to indicate the kind of the illumination light from a light source discrimination device 20 is inputted into a table 31, mixture ratio control signals k1 and k2 corresponding with the kind of the illumination light are outputted from the table 31. The table 31 is constituted by a memory device similarly to a table 21. The mixture ratio control signals k1 and k2 of the color difference signal are converted into an analog value by D/A converters 32 and 33, control the mixture ratio in mixture circuits 40 and 41 and change the mixture ratio of the color difference signal according to the kind of the illumination light so that the color reproducibility of the memory color of the skin color may be improved. Thus, the video output signal of the good reproducibility of the memory color can be constantly obtained even when the kind of the illumination light is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application in Industry-1-] The present invention relates to an imaging signal processing device for a color video camera, and more particularly to an imaging signal processing device with good color reproducibility such as memory colors.

[Prior art] Figure 3 shows Japanese Patent Application No. 62-135732 and Japanese Patent Application No. 62-135732.
This is a block circuit diagram of the imaging signal processing system of a color video camera shown in Publication No. 2-134265, etc., in which (1) is a lens, (2) is an image sensor, (3) is a color separation circuit, and (4) is an R channel. (hereinafter referred to as r RC) (referred to as J) gain control circuit, (5) is a 13 channel (hereinafter referred to as r B C11
J) gain control circuit, (6) a process circuit, (7
) is a matrix circuit, (8) is an encoder circuit, (9)
is a synchronization signal generation circuit, (10) is an output terminal for video transmission,
(20) is a light source discrimination device, (21) is a white balance control signal output table (hereinafter referred to as "table"), (2
2) and (23) are D/Δ converters.

Next, the operation will be explained. The image light incident on the lens (1) forms an image on the image sensor (2). The image sensor (2) is driven by the synchronization signal input from the synchronization signal generation circuit (9) and outputs an imaging signal. The I (transmission After signal processing such as black clipping, gamma correction, and white clipping is performed in the process circuit (6), the matrix circuit (7)
Y signal.

An RY color difference belief and a BY color difference belief are generated.

Of these, the RY color difference signal and the l3-Y color difference signal are
In the encoder circuit (8), a synchronization signal generation circuit (9
) is modulated by the color subcarrier signals fscRY and fscB-Y input from
111 power is applied from the output terminal (10).

The light source discrimination device (20) detects the ratio of R1(j, 13 components, etc. included in the illumination light illuminating the subject and the ripple component included when the illumination light source is a discharge lamp, etc.). The type is determined and a determination signal is output.For details of this determination operation, see Japanese Patent Application No. 62-135.
732 v3 and Japanese Patent Application No. 134265/1983, etc., so the explanation will be omitted here. When the discrimination signal indicating the type of illumination light is input to the table (21), the self-balance control signal "igl, g2 corresponding to the type of illumination light is output from the deble (21). Normally, a drying device such as a 50M is configured with a J/A converter (22), (23
) is the manually input white balance control signal>'1. Convert gz to analog 11°1, Rch gain control circuit (4
) 1301) Controls the gain of the gain control circuit (5). In other words, the deble (21) outputs a gain control value such that a value of 1 correctly adjusts the white balance of the G and B signals, depending on the type of illumination light.

In this way, the conventional imaging signal processing device detects the ratio of the R, G, and B components of the four bright lights, the ripple component, etc., determines the seed lamp 1 of the illumination light, and detects the type of the illumination light. Highly accurate white balance adjustment is achieved by controlling the levels of l'<transmission level and Y3 accuracy degree according to the following.

[Problems to be Solved by the Invention] Since the conventional imaging signal processing device is configured as shown in 1-J below, the performance of self-balance adjustment has improved, but there are also the following problems.

The vector diagram shown in Figure 4 shows red, yellow, skin tone,
It is a figure which shows the color reproducibility when white Char 1. is imaged.

The hexagonal diagram not shown in Figure 5 is for white fluorescent lamps (color temperature 4
FIG. 4 is a diagram showing the color reproducibility when the same red, yellow, skin tone, and white charts as in FIG.

Rch gain control circuit (4) and Bch gain control circuit (5) for white balance adjustment for both illumination lights.
), the values of the gain control values +gl and g2 are almost equal, and the white balance is adjusted even in FIGS. 4 and 5. However, white fluorescent lamps have poor color rendering properties, so as shown in FIG. 5, the phases and amplitudes of red, yellow, skin color, etc. are different from those in FIG. 4. Especially in Figure 4, the phase of skin color is
While the phase is 123°, which is preferable, it is 137° in FIG. 5, which gives the skin a yellowish tinge, which is a serious visual problem. In particular, since skin color is a memory color, the tolerance range is particularly narrow for changes in phase. This problem is most noticeable in fluorescent lamps J, which have good color rendering properties, and white fluorescent lamps, which have poor color rendering properties.

As a method for improving color reproducibility that focuses only on changes in color temperature of illumination light, for example, the 1986 Television Society of Japan National Conference Lecture - R, Old Page - Page 82 [Color Reproduction in Complete Color Difference Line Sequential Cameras] However, sufficient effects could not be obtained for illumination light with poor color rendering properties as described above.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain an imaging signal processing device that can obtain good color reproducibility even under illumination light with poor chromaticity.

[Means for Solving the Problems 1] An imaging signal processing device according to the present invention includes a light source discrimination device;
Based on the "I'll separate signal" of this light source discriminator, the ratio of the second color difference signal to be mixed with the first color difference signal or the ratio of the second color difference signal to be mixed with the first color difference signal, or The present invention is characterized in that it includes means for changing the mixing ratio of at least one of the ratios of the first color difference signal to be mixed with the second color difference signal, independently of the self-balance adjustment.

"Operation" The means for changing the mixing ratio of color difference signals in the present invention changes the mixing ratio of color difference signals according to the type of illumination light so that the color reproducibility of memory colors such as skin colors is improved. Even if the type of illumination light changes, a video output signal with good color reproducibility of memory colors can always be obtained.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the same components as in the conventional example shown in FIG.
), (33) is a D/A converter, (40) is R-
Mixing circuit that mixes the B-Y color difference signal with the Y color difference signal (4
1) is a mixing circuit that mixes a B-Y color difference signal and an RY color difference signal.

Next, the operation will be explained. When the illumination light type is input from the light source discriminator (2o) to the table (31), the mixture ratio control corresponding to the type of illumination light is performed from the table (31). Signal kl, 2:
] 1 power is applied. Like the daple (21), the daple (3I) is constituted by a memory device such as a ROM. The color difference signal mixing ratio control signal kl is converted into an analog value by the /Δ converter T32), +33), and the mixing ratio in the mixing circuits (40) and (41) is controlled as shown in the following equation. , (RY), = (RY) +kl (+3-Y)
(+3-Y) , =2 (RY) + (B-Y)
Color difference signal (RY) 1. (13Y) I is a mixed circuit (4
01, output from (41). Mixing ratio control signal k1.
The value of 2 is set to k1=O in the case of the illumination light in Figure 4 (natural light on a sunny afternoon), and k+=-0 in the case of the white fluorescent lamp in Figure 5.
, 26 to 2=0. When set to I4, almost satisfactory color reproducibility can be obtained for skin tones as shown in FIG.

In the above embodiment, the case of a color video camera using R-Y and B-Y color difference signals has been explained, but the same structure can be used even when using IQ color difference signals or other color difference signals, and the same effect can be obtained. can get.

[Effects of the Invention] As described above, according to the present invention, the mixing ratio of color difference signals is adaptively changed according to the type of illumination light so as to obtain good color reproducibility for memory colors such as skin tones. : Since the color video camera is configured in two parts, it is possible to obtain a color video camera with excellent color reproducibility.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram of an imaging signal processing system according to an embodiment of the present invention, Fig. 2 is a vector diagram showing the color reproducibility of this embodiment, and Fig. 3 is a diagram of a signal processing system of a conventional color video camera. The block circuit diagrams, FIGS. 4 and 5, are vector diagrams showing the color reproducibility of this conventional example. (4), (5)...gain control circuit, (6)...
Process circuit, (7)...matrix circuit, (8)...
... Encoder circuit, (20) ... Light source discrimination device, (
21) Self-balance control signal output table, (31
)...Mixing ratio control signal output table, (401, (
411... Mixed circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A means for determining the type of illumination light of the subject; a means for adjusting the level of a color signal so that the white balance of the output video signal becomes an optimum value based on the determination result; and a skin color of the output video signal. a ratio of a second color difference signal to be mixed with the first color difference signal and a ratio of the first color difference signal to be mixed with the second color difference signal to compose the output video signal so as to improve color reproducibility of memory colors such as An imaging signal processing device for a color video camera, comprising means for adaptively changing at least one of the mixing ratios based on the above-mentioned determination result.