JPH0591527A - Chrominance signal processing circuit - Google Patents

Abstract

PURPOSE:To easily adjust processing with compact circuit constitution by inputting difference signals respectively between two primary color signals to a multiplier and inputting also coefficients calculated by an arithmetic circuit to the multiplier. CONSTITUTION:Difference signals (R-G and B-G signals) between two respective primary color signals are inputted to the multiplier 15, plural coefficients (a) to (d) calculated from hue adjusting data and color difference gain adjusting data by the arithmetic unit 16 are inputted to the multiplier 15 and two color difference signals (R-Y and B-Y signals) are obtained from the output side of the multiplier 15. Since processing can be executed only by the multiplication of the difference signals respectively between two primary color signals by the coefficients (a) to (d), the multiplication of a matrix can be executed only by one operation. Consequently the circuit size can be made compact, and since the correction of the coefficients (a) to (d) is simultaneously executed, processing can easily be adjusted based upon rectangular R-Y and B-Y axes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal processing circuit suitable for use in a CCD color video camera.

[0002]

2. Description of the Related Art In general, a CCD color video camera such as that shown in FIG. 2 has been proposed. In FIG. 2, reference numeral 1 denotes an optical system, which supplies a subject image from the optical system 1 to a photoelectric conversion device 2 including a CCD, and a red (R) signal obtained at an output side of the photoelectric conversion device 2 including the CCD. , The green (G) signal and the blue (B) signal are supplied to the A / D conversion circuit 4 for converting an analog signal into a digital signal through the sampling and holding circuit and the AGC circuit 3, and the A / D conversion circuit 4
The output signal of the D conversion circuit 4 is supplied to the synchronization circuit 5, and the synchronization circuit 5 converts the dot-sequential R signal, G signal, and B signal into simultaneous signals.

R obtained at the output side of the synchronization circuit 5,
A simultaneous signal of G and B signals is supplied to the luminance signal processing circuit 6 to form a luminance (Y) signal, and the Y signal obtained at the output side of this luminance signal processing circuit 6 is converted into a digital signal into an analog signal D The signal is supplied to one input terminal of the adder circuit 8 via the / A conversion circuit 7.

R, which is obtained at the output side of the synchronization circuit 5,
White balance adjustment circuit 9 for simultaneous G and B signals
And the RG signal and BG via the gamma correction circuit 10.
It is supplied to the difference signal forming circuit 11 that forms a signal, and the R-G signal and B-
The G signal is supplied to the color signal processing circuit 12, and in this color signal processing, two color difference signals RY signal and BY signal are obtained from the RG signal and BG signal. The BY signal is supplied to the encoder circuit 13, and in the encoder circuit 13, the chroma signal C of the NTSC system is supplied.
The chroma signal C is supplied to the other input terminal of the adder circuit 8 via the D / A conversion circuit 14, and the adder circuit 8
A color television signal is obtained at the output terminal 8a.

Conventionally, as a color signal processing circuit 12 for obtaining a color difference signal RY signal and a BY signal from the RG signal and the BY signal, as shown in FIG. The obtained RG signal and BG signal are RY / B
-Y matrix circuit 12a supplies this RY / B
-In the Y matrix circuit 12a,

[0006]

[Equation 1]

Matrix multiplication is performed, and the RY 'signal, B-
Y'signal is obtained, and the RY 'signal and B-
The Y'signal is supplied to the hue adjustment and color difference gain adjustment circuit 12b. In the hue adjustment and color difference gain adjustment circuit 12b, an RY gain adjustment signal R is externally applied.
-YGain, BY gain adjustment signal B-YGain,
The RY hue adjustment signal R-YHue and the BY hue adjustment signal B-YHue are adjusted signal input terminals 12c, 12d, 1
2e and 12f are supplied, and hue adjustment and color difference gain adjustment are performed. This hue adjustment and color difference gain adjustment circuit 12b
In

[0008]

[Equation 2]

The above matrix operation is executed to obtain two color difference signals RY signal and BY signal. In this case, the RY 'axis and the BY' axis are orthogonal to each other, and the hue adjustment and the color difference gain adjustment are performed with reference to the RY 'axis and the BY' axis. It's easy.

However, in the conventional color signal processing circuit 12 as shown in FIG. 3, since the multiplication of the matrices of equations 1 and 2 is repeated twice, there is a disadvantage that the circuit scale becomes large.

In order to eliminate this inconvenience, as shown in FIG. 4, the R-G signal and the B-G signal are directly supplied to the hue adjustment and color difference gain adjustment circuit 12g, and the hue adjustment and the color difference gain adjustment are performed to perform the R adjustment. It is also possible to obtain -Y and BY signals, but in this case RG that is not orthogonal
Since the hue and the gain are adjusted with reference to the axis and the B-G axis, there is a disadvantage that the adjustment is extremely difficult unlike the adjustment with respect to the orthogonal R-Y axis and B-Y axis.

In view of the above problems, an object of the present invention is to propose a color signal processing circuit which can be adjusted relatively easily with a relatively small circuit configuration.

[0013]

In the color signal processing circuit of the present invention, for example, as shown in FIG. 1, two difference signals (R-G signal and B-G signal) of two primary color signals simultaneously are input to a multiplying circuit 15 as well as this difference signal. Coefficients a, b, c calculated by the arithmetic unit 16 from the hue adjustment data and the color difference gain adjustment data are stored in the multiplication circuit 15.
d is input, and two color difference signals (RY signal and BY signal) are obtained at the output side of the multiplication circuit 15.

[0014]

According to the present invention, the difference signals of two primary color signals are multiplied by the coefficients a, b, c and d calculated by the arithmetic unit 16 from the hue adjustment data and the color difference gain adjustment data. Since the multiplication is performed only once, the circuit scale is reduced and the coefficient is corrected at the same time. Therefore, the adjustment is performed with reference to the RY axis and the BY axis which are orthogonal to each other, and this adjustment becomes relatively easy. ..

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the color signal processing circuit of the present invention will be described below with reference to FIG. 1. In this example, the R-G signal and the B signal obtained at the output side of the difference signal forming circuit 11 as shown in FIG. The -G signal is supplied to one input side of the multiplication circuit 15 which constitutes the hue adjustment and color difference gain adjustment circuit. Further, in FIG. 1, reference numeral 16 denotes an arithmetic unit composed of a microcomputer, and the four adjustment data input terminals 16a, 16b, 16c and 16d of the arithmetic unit 16 are respectively RY.
Gain adjustment data R-YGain, BY Gain adjustment data B-YGain, RY Hue adjustment data R-YHu
e and BY hue adjustment data B-YHue are supplied, and in this arithmetic unit 16,

[0016]

[Equation 3]

Then, the coefficients a, b, c and d are calculated.
And the coefficients a, b, c and d obtained by the arithmetic unit 16 are supplied to the other input side of the multiplication circuit 15 respectively, and in the multiplication circuit 15,

[0018]

[Equation 4]

The multiplication is performed so that the RY signal and the BY signal of the two color difference signals are obtained at the output side of the multiplication circuit 15. According to this example, the R-G signal, the B-G signal, and the R-
Y hue adjustment data R-YHue, BY hue adjustment data B-YHue, RY gain adjustment data R-YGain
And by multiplying the coefficients a, b, c, and d obtained by the calculation in the calculation circuit 16 from the BY gain adjustment data B-YGain in the multiplication circuit 15, the two color difference signals R-Y signal and B- Since the Y signal is obtained, it is only necessary to multiply the matrix once, and according to this example, there is an advantage that the circuit scale becomes small, and the coefficients a, b, c and d have RG axis and B-. G
Coefficient for converting the axis to the RY axis and the BY axis

[0020]

[Equation 5]

Since the adjustment data is also included, the adjustment data is obtained with reference to the RY and B axes which are orthogonal to each other, and this adjustment has the advantage that it is easy as in the example of FIG.

In the above embodiment, an example in which the RY signal and the BY signal are obtained from the RG signal and the BG signal has been described, but instead of this, other two primary color signals are used. It can be easily understood that two color difference signals may be obtained from the difference signal. Further, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0023]

According to the present invention, there is an advantage that the circuit configuration is relatively small and the adjustment is relatively easy.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a color signal processing circuit of the present invention.

FIG. 2 is a configuration diagram showing an example of a CCD color video camera.

FIG. 3 is a configuration diagram showing an example of a conventional color signal processing circuit.

FIG. 4 is a configuration diagram showing an example of a color signal processing circuit.

[Explanation of reference numerals] 11 difference signal forming circuit 12 color signal processing circuit 15 multiplication circuit 16 arithmetic unit

Claims (1)

[Claims] 1. A difference signal between two primary color signals is input to a multiplication circuit, and a coefficient calculated by an arithmetic unit from hue adjustment data and color difference gain adjustment data is input to the multiplication circuit, and an output side of the multiplication circuit is input. A color signal processing circuit characterized in that two color difference signals are obtained.