JPS61210784A - Automatic hue correcting device - Google Patents

Abstract

PURPOSE:To enable hue correction corresponding to the average value of hue deviation of a skin-color signal by providing an amplifier circuit that supplies a Q signal to a hue adjusting circuit as an adjusting signal and a circuit connected to the output end of the amplifier circuit and supplies an average adjusting signal corresponding to the average value of the adjusting signal. CONSTITUTION:An R-Y color difference signal obtained in the first output terminal 13 and a B-Y color difference signal obtained in the third output terminal 15 are synthesized in the first composing circuit 22 and a Q signal is generated in its output terminal. The Q signal is amplified by an amplifier circuit 24, and applied to an average adjusting signal generating circuit 26 to generate an average adjusting signal. The R-Y color difference signal and B-Y color difference signal are synthesized in the second synthesizing circuit 23 and an I signal is generated in the output terminal of the synthesizing circuit 23. The I signal is applied to a controlling circuit 25, and synthesized with a reference signal (Vref) in the controlling circuit 25. When the level of the I signal is larger than the level of the reference signal, a controlling signal is generated from the controlling circuit 25, and the amplifier circuit 24 becomes the state of operation, and the Q signal is amplified and supplied to the average adjusting signal generating circuit 26.

Description

Detailed Description of the Invention (a) Field of Industrial Application The present invention relates to an automatic hue correction device for a color television receiver that can automatically correct the hue, and in particular, the invention relates to an automatic hue correction device for a color television receiver, which is capable of automatically correcting the hue. The present invention relates to an automatic hue correction device capable of detecting a deviation and correcting hue deviations of other colors according to the average of the hue deviations.

(b) Prior Art A hue adjustment device is known that adjusts hue by manually operating a hue volume. In addition, the magazine rICDATA HO published by Nihon Chic Data Co., Ltd.
T 5ERVICEj June 1981 issue No. 6-3
On page 22, there is an IC (integrated circuit) HA1143 with a built-in hue automatic correction device that can automatically correct the hue.
6 is listed. The IC, as shown in FIG.
A second band amplification circuit (2) amplifies the composite video signal applied to the input terminal (1), and amplifies the output signal of the first band amplification circuit (2), and also amplifies the output signal of the first band amplification circuit (2) and amplifies the composite video signal applied to the input terminal (1). a second band amplification circuit (3) that separates the first signal from the second band amplification circuit (3);
an ACC (automatic chroma control) circuit (4) that controls the gain of the first band amplifier circuit (2) according to the strike signal; a phase comparator (5); and a VCO (pressure controlled oscillator) (6); a PLL (phase locked loop) that generates a CW (local subcarrier) signal synchronized with the burst signal.
a circuit (7) and a hue volume (8), the CW
A hue adjustment circuit (9) that adjusts the hue by adjusting the double signal phase and a phase shift of the output signal of the hue adjustment circuit (9) by φ, CW, I, (R to Y axis reference subcarrier ) The phase of the output signal of the first phase shift circuit 00) which generates the signal (00) and the hue adjustment circuit (9) is shifted by φ2, CW! l,
(B-Y axis reference subcarrier) signal; a second phase shift circuit (11) that generates a B-Y axis reference subcarrier signal; and demodulates the R-Y color difference signal using the CW, . -Y
A demodulation circuit 04 is provided which demodulates the color difference signal and further matrixes the R-Y color difference signal and the B-Y color difference signal to generate a G-Y color difference signal. Therefore, if the circuit shown in Fig. 2 is used, by applying a composite video signal to the input terminal (1), the first, second and third terminals Q3], (Q3 and 05)
R-Y color difference signal, G-Y color difference signal and B-Y color difference signal, respectively.
Color difference signals can be generated.

Furthermore, the circuit in Fig. 2 uses a CW signal whose phase is shifted by φ3.
, (Q-axis reference subcarrier) signal is generated by a third phase shift circuit (
I fi) and the CW whose phase of the CW multiplied signal is shifted by φ4,
Fourth phase shift circuit 07 that generates (I-axis reference subcarrier) signal
), a Q-axis demodulation circuit (1 to 1) that demodulates the chroma signal on the Q-axis using the CWQ signal to generate a Q signal, a demodulation circuit (1) and an amplifier circuit (20) that amplifies the Q signal and adjusts the hue adjustment circuit (9) using its output signal.
), compare the ■signal with a reference signal (Vref), and operate the amplifier circuit when the ■signal is positive;
A hue correction device is provided, which comprises a control circuit ρυ that disables the amplifier circuit (2) when the signal (2) is small.

Therefore, when the chroma signal approaches the ■ axis and the level of the ■ signal becomes small, the amplifier circuit (2α) is activated, and the hue adjustment circuit (9) is adjusted by the Q signal. The hue can be adjusted so that the signal is on one axis.The signal on the above-mentioned (■) axis corresponds to the skin tone,
The adjustment means correcting a color close to a skin color to a skin color.

The phase relationships among the CW multiplied signal CWR-7 signal, CW, A signal, Q signal, and I signal are as shown in FIG.

ρ9 Problems to be Solved by the Invention However, the automatic hue correction device shown in FIG. No correction effect is produced.Therefore, the gain of the amplifier circuit (2) must be precisely adjusted, which has the drawback of requiring time and effort.Furthermore, the automatic hue correction device shown in FIG. However, if the adjustment characteristic curve of the hue adjustment circuit (9) and the characteristic curve of the Q signal do not match, accurate correction cannot be performed.

Additionally, in general, if a color close to the skin color near one axis is subject to phase distortion, there is a high possibility that other colors are also subject to phase distortion, so it is necessary to correct the other colors along with the color close to the skin tone. is a preferred method for hue correction.

B) Means for Solving the Problems The present invention has been made in view of the above points, and includes a synthesis circuit for synthesizing a Q signal from a color difference signal, and supplying the Q signal as an adjustment signal to a hue adjustment circuit. an amplifier circuit; a control circuit that controls the operation of the amplifier circuit according to the color difference signal;
The present invention is characterized in that it includes a circuit connected to an output end of the amplifier circuit and supplying an average adjustment signal corresponding to an average value of the adjustment signals to the phase adjustment circuit.

(E) Function According to the present invention, hue correction can be performed in accordance with the average value of the hue deviation of the skin color signal, and correction of colors other than skin color can also be performed.

(F) Embodiment FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which R-24 is obtained at the first output terminal 03 of the demodulation circuit (12).
Y color difference signal and third output terminal (1!ilK obtained B-Y
a first synthesis circuit that synthesizes the color difference signal and generates the Q signal; (
23) is the first output terminal (131) of the demodulation circuit (121).
-Y color difference signal obtained at the third output terminal 051 and the B-Y color difference signal obtained at the third output terminal 051 are combined to generate a signal
a synthesis circuit, (241 is an amplifier circuit that amplifies the Q signal obtained from the first synthesis circuit I22) and supplies it as an adjustment signal to the hue adjustment circuit (9);
a control circuit that compares the signal obtained from the second wrinkle with a reference signal (Vref) and generates a control signal for operating the amplifier circuit (24) when the engineering signal is positive;
) is an average adjustment signal generation circuit that is connected to the output terminal of the amplifier circuit (04) and supplies an average adjustment signal corresponding to the average value of the adjustment signals obtained from the amplifier circuit (24J) to the hue adjustment circuit (9). be.

As in the case of the conventional circuit shown in Fig. 2, the composite video signal applied to the input terminal (1) is amplified by the first band amplification circuit (2) and the second band amplification circuit (3), and the chroma signal and burst signal are amplified by the first band amplifier circuit (2) and the second band amplifier circuit (3). Separated into signals. The chroma signal is applied to the demodulation circuit (12+) and demodulated, the burst signal is applied to the phase comparator (5) and used to create a CW multiplied signal, and is applied to the ACC circuit (4). The phase comparator (5) is used for gain control.
Together with CO (61), it constitutes a PLL circuit (2), and the burst signal and the output signal of (6) C0 (6) are phase-compared by a phase comparator (5). 6) At the output end, there is a C synchronized with the burst signal.
W times signal is generated.

The CW multiplied signal is applied to the hue adjustment circuit (9) and used for hue adjustment. 1st and 2nd phase shift circuit 00)
and 01) generate a CWR-□ signal and a CW signal whose phases are shifted by φ1 and φ2, respectively. Then, the CW8-7 signal is applied to the demodulation circuit (121) to demodulate the R-Y color difference signal, and the CW8-7 signal is demodulated to the
By applying the WB-7 signal to the demodulation circuit α2, B
-Y color difference signal is demodulated. Furthermore, a G-Y color difference signal is obtained by matrixing the demodulated R-Y color difference signal and the B-Y color difference signal. The R-Y color difference signal, G-
The Y color difference signal and the B-Y color difference signal are the first and second signals, respectively.
and the third output terminal (13), (2) and (151) are transmitted to the subsequent stage and used for color reproduction.

The RY color difference signal obtained at the first output terminal Q31 and the 13-Y color difference signal obtained at the third output terminal Q51 are combined by the first synthesis circuit (221), and a Q signal is generated at its output terminal. The Q signal is amplified by the amplifier circuit (2) and then applied to the average adjustment signal generation circuit (A), so that the average adjustment signal generation circuit (26) generates an average adjustment signal. The Y color difference signal and the B-Y color difference signal are the second
The synthesis circuit (C) generates an I signal at the output terminal of the second synthesis circuit (251).The I signal is applied to the control circuit CI! Vref). Now, if the level of the I signal is higher than the level of the reference signal, a control signal is generated from the control circuit (two) and the amplifier circuit (
24J becomes operational, amplifies the Q signal, and supplies it to the average adjustment signal generation circuit (26). On the other hand, if the level of the I signal is lower than the level of the reference signal, the control signal is not generated and the amplifier circuit (241) does not operate, so automatic hue adjustment is not performed.

FIG. 4 shows an example in which the average adjustment signal generating circuit (26) is configured by a capacitor (5). The Q signal obtained from the first synthesis circuit (2) is amplified by the amplifier circuit c!4 according to the control signal from the control circuit C clause, and the
2'0. Therefore, the adjustment signal obtained at the output terminal of the amplifier circuit &4) is smoothed by the capacitor 0'7), and an average adjustment signal corresponding to the average value of the adjustment signal is supplied to the hue adjustment circuit (9). . In addition, resistance (2
This is to prevent the load impedance of the average adjustment signal generation circuit (26) from changing depending on the position of the movable terminal of the chanting hue box IJ, - (8). The amplifier circuit (2
4) As mentioned earlier, ■When the signal is above a predetermined level,
That is, since it is activated when the received chroma signal is near the skin color, the average adjustment signal obtained from the capacitor (27) becomes the average value of the amount of deviation from the skin color of the color near the skin color. The level of the average adjustment signal in the amplifier circuit is determined according to the operation of the amplifier circuit, and the control according to the accumulated charge of the amplifier circuit (capacitor 07) continues even after the amplifier circuit (24J becomes inoperable). By arranging 27), it is possible to automatically correct the hue of not only colors near skin tone but also other colors. Especially during the correction period, the capacitor (
Since it is determined according to the discharge time constant of two forces, it is possible to arbitrarily perform hue correction for colors other than colors near skin tone.

FIG. 5 shows the average adjustment signal generation circuit (26) connected to the resistor (29).
) and a capacitor (30) in series. With such a circuit configuration, the amplifier circuit (24
) is operating and the adjustment signal is generated, the resistor 09
Since the instantaneous value of the adjustment signal is generated at ), correction of colors near the skin color is performed according to the instantaneous value, and accurate skin color correction can be performed. In addition, when a color other than the color near the skin tone arrives, the operation of the amplifier circuit (24) is stopped, or an average adjustment signal is generated according to the accumulated charge on the capacitor side, so that the color near the skin tone is generated, as in the case of FIG. It is possible to perform hue correction for colors other than the above.

In Figure 6, the average adjustment signal generation circuit (26) is connected to the resistor C32.
, a capacitor (g), and a first capacitor connected in opposite directions to each other.
and a second diode (34) and a limiter (g) made of six powders. In the case of Figure 6,
The terminal voltage of capacitor C (31) is ±vf (vf is the first
and the voltage across the second diode l34) and r3Q). Therefore, excessive adjustment of the hue adjustment circuit (9) can be prevented.

Next, I will explain the automatic hue correction operation. Now, if there is a chroma signal indicated by A- in FIG. 7 (shifted by α degrees from the ■ axis), the level of the Q signal will be B, and the level of the ■ signal will be C. The level C of the above ■signal is the reference signal (
If it is a dog than the level of Vref), the amplifier circuit (,!(
A) is activated to amplify the Q signal, and the average adjustment signal is applied to the hue adjustment circuit (9). When the average adjustment signal is applied to the hue adjustment circuit (9), the CW multiplication signal phase is rotated according to the level of the average adjustment signal, and the outputs of the first and second phase circuits (10) and aυ are accordingly rotated. The phases of the signals CWR-□ and CWB-1 are also rotated. This means that the demodulation axis rotates in the demodulation circuit (21), and as shown in FIG.
The B-Y axis also rotates α degrees to become the (B-Y)' axis.
) becomes the axis. In the case of the present invention, since the Q signal is created from the R-Y color difference signal and the B-Y color difference signal, the first axis and the Q axis also rotate according to the rotation of the demodulation axis, and when the correction is completed ( In FIG. 8), the chroma signal AIJ'' overlaps with the -■ axis, and the level of the Q signal becomes zero.

In other words, the automatic correction according to the present invention rotates the demodulation axis so that the level of the Q signal becomes small. Then, when the chroma signal becomes a color other than skin tone that is sufficiently shifted from one axis, the level of the ■ signal changes to the reference signal (Vre
f), the operation of the amplifier circuit 04) is stopped by the control operation by the control circuit (25)K, and the adjustment signal is no longer generated. However, the average adjustment signal generation circuit (
Since the average adjustment signal continues to be generated due to the holding ability of 2e, colors other than the skin color are also corrected according to the average value of the amount of color shift in the vicinity of the skin color, eventually achieving hue correction for all colors.

(g) Effects of the Invention As described above, according to the present invention, the hue of all colors can be automatically corrected according to the average value of the amount of deviation from the skin color of colors near the skin color. Therefore, it is possible to correct the hue shift of colors other than the colors near the skin color, which are caused by the same cause as the hue shift of the colors near the skin color. In particular, if the average adjustment signal generating circuit is configured with a series circuit of a resistor and a capacitor as in the embodiment shown in FIG. Since it can be corrected according to the value, more accurate automatic hue correction can be achieved. Furthermore, if a limiter is inserted as in the embodiment shown in FIG. 6, if the cause of the hue shift of a color near the skin tone is abnormally large compared to that of other colors, over-correction of the other colors will be performed. can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a conventional hue correction device, FIG. 3 is a vector diagram showing the phase relationship of subcarriers, and FIG. Figure 5 is a circuit diagram showing an example of the average adjustment signal generation circuit, Figure 5 is a circuit diagram showing another example, Figure 6 is a circuit diagram showing still another example, Figure 7 is a chroma signal before correction. and FIG. 8 is a vector diagram showing the relationship between the corrected chroma signal and each axis. Explanation of main drawing numbers (9)...hue adjustment circuit, 02...demodulation circuit,
(2)...First synthesis circuit, (23)...Second synthesis circuit, (24)...Amplification circuit, (2!'i)...
Control circuit, (26)...average adjustment signal generation circuit. Applicant Sanyo Electric Co., Ltd. and one other representative Patent attorney Shizuo Sano Figure 3 (zi\Q') Figure 4

Claims (1)

[Claims] (1) a demodulation circuit that demodulates three color difference signals from a chroma signal, a hue adjustment circuit that applies a carrier signal for demodulation to the demodulation circuit, and a synthesis circuit that synthesizes a Q signal using the color difference signals; an amplifier circuit that amplifies the Q signal and supplies it as an adjustment signal to the hue adjustment circuit; a control circuit that applies a control signal according to the color difference signal to the amplifier circuit to control the operation of the amplifier circuit; and the amplifier circuit. and a circuit connected to the output terminal of the controller to generate an average adjustment signal corresponding to the average value of the adjustment signals, and the hue is adjusted by supplying the average adjustment signal to the hue adjustment circuit. An automatic hue correction device featuring: