JPS5850885A - Color video signal processor - Google Patents

Abstract

PURPOSE:To obtain an amplified output color signal as a green signal without exerting any influence upon other color signals and a luminance signal, by detecting the green signal from the luminance signal, red signal, and blue signal, and amplifying a chrominance signal according to the level of the green signal. CONSTITUTION:A signal output from an image pickup tube 1 is inputted through a preamplifier 3 to a processing circuit 5 to extract a wide-band luminance signal EyH, a luminance signal level Ey, a red level ER, and a blue level EB, which are inputted to an encoder together with 0 and 90 deg. out-of-phase subcarriers SubA and SubB, thereby outputting a chrominance signal Ec. The signals EyL, ER, and EB are inputted to a correcting-signal generating circuit 9 to generate hue vectors EG and EG' of green and when the EG' is much smaller, a correcting signal Sc which corresponds to the EG is sent out. The chrominance signal Ec is amplitude-corrected by a correcting circuit 11 with the correcting signal Sc, and the corrected chrominance signal E'c is synthesized with the EyH and a composite synchronizing signal SH, thereby outputting a final NTSC signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color video signal processing device, and more particularly to a color video signal processing device capable of correcting a color signal when obtaining an output color signal. Conventionally, as a correction circuit for correcting a color signal, For example, a 0 matrix color correction circuit including a matrix color correction circuit receives, for example, the brightness IIIL signal YL before correction.

The levels of red signal R9 and green signal B are respectively (YL.

R・B), and the respective levels after correction (YL/, R').

), then (YL/ , R', B')t=IM(YL f
This is done by creating a resistance matrix M so that RI B )t. With this method, for example, if you try to correct a green light (hereinafter referred to as G), other things will be affected, so
It is not suitable for correcting only G. Various other methods have been proposed, but G does not only correct one color, but also affects other colors.In addition, in a single-tube or single-plate color video camera, the green signal G cannot obtain a sufficient level due to the influence of the filter.

In view of the above-mentioned points, the present invention aims to provide a color video signal processing device capable of correcting only the level of a green signal without affecting other color signals or luminance signals.

An embodiment of the present invention will be described in detail below.

FIG. 1 is a vector diagram of hue. Peng indicates the hue vector of the edge, and 5 indicates a hue vector having a 9σ phase different from that of green.

Now, if E() has a certain size and the play has only a sufficiently large proportion to the size of E(), then only then will the video signal contain most of the green color component. Become. If you want to enhance or decrease only green, you can take the values of EG and OK, use the above method to determine whether it is green, and only increase or decrease the amplitude of the carrier color signal when it is green. K becomes.

By the way, EG is expressed as 4 ores, where Ey and h lines become, and EQ and Eq are Eζ e Ea,
It can be expressed as Ey.

Generally, Ey is used in color television and other imaging devices.

Since ER and E- exist, both EQ and EQ can be created extremely easily. Create EG and 4, and when 9 is sufficiently leading to EQ, E(.

By adjusting the amplitude of the carrier color signal according to the output of K, it is possible to enhance or reduce the output of the input color signal only when it is green.

FIG. 2 is an example of a block diagram of a control circuit implementing the present invention.

In the figure, 1 is a single-tube image pickup tube, 3 is a buri amplifier, and 5
are the wide band brightness signal EyH and the narrow band brightness signal EFL =
A process circuit for obtaining EB and El, 7 an encoder for obtaining a carrier color signal Ee, 9 a correction signal creation circuit, 11 a correction circuit for correcting the signal Ec to obtain a corrected carrier color signal E, 13 is a synchronization signal generation circuit, 15 is NT
This is a synthesis circuit for obtaining an SC signal.

Explain the operation.

The signal output from the image pickup tube 1 enters the process circuit through the preamplifier 3, where various processing is performed, and Eyh, 'B
Extracted as 'l', ER, EB.

EyLI E class, E is 3.58% & subcarrier 5ubA, 5ubB with phase of 0° and 9σ
It is also input to the encoder 7 and output as a carrier color signal Ec.

On the other hand, EyL and Ey -Ext enter the correction signal creation circuit 9, where EGI and EQ are first created, and when the play is sufficiently advanced! Send out correction signals S and C according to Q. The amplitude of the carrier color signal Ec is corrected by the correction signal SC in the correction circuit 11. The corrected carrier color signal E♂ is combined with T's and the composite synchronization signal SH, and is output as a final NTSC signal.

FIG. 3 is a block diagram of an embodiment of the correction signal generation circuit 9 and the first positive circuit 11 shown in FIG. 2, and FIG. 4 shows an example of a circuit realizing this block diagram. First, FIG. 3 will be explained.

EFL, from E1, EB -EB, EB
-E- is created by the arithmetic circuit 21.2a23. EB is 0
The level is clamped to a constant level and sent to a correction circuit.
The chroma signal He is amplified or decreased depending on the difference from the wrinkle constant level to obtain a corrected chroma signal E/. however,
Two switches 26 and 27 are connected in series on the way to the clamp, and each switch acid
R-EB.

It turns on only when EB % is less than a certain potential. Therefore, the correction section uses E4 only when the input color signal is green.
will be sent, and in the end, correction will be performed only when the color is green.Next, FIG. 4 will be explained.

~L t EB -E is connected to two video amplifiers VAI and VA2 through capacitors C1 to C3, respectively, and Bt, , E -EB by resistive coupling.

and El-EI! Create. ER-El is clamped and sent to the first comparator OPI.

One input terminal of the comparator OPI is connected to an adjustable constant reference potential Els K II. The reference potential Es1 is selected in consideration of noise and the like. When F (E > Eat, the output of comparator OP1 becomes a high level and is not transmitted to the transistor Tr4 connected beyond it. When Eg - Km < Eat, the output of comparator OP1 becomes high level.
Since the PI output becomes a low level and the transistor Tr4 is not turned on, the output signal is transmitted to the subsequent stage. Also E--pie
The shoe is connected to the comparator, but the subsequent operation is E.
0, which is the same as in the case of z-EB, that is, comparator OP
I and the transistor Tr4 correspond to the switch 26 in FIG. 3, and the comparator OP2 and the transistor T4 correspond to the switch 27. In this way, the EG Only when 1, i.e.
When the color signal is green (also when the input color signal is white, ER14, Ea
EB <Eat, but in that case, only E (, is also sufficiently small) is connected to IRK. 0 This output is connected to the clamp voltage (CLPK) at a constant potential Ea, and after the IICO level is clamped, it is connected to the balanced modulator BM. Balanced signal is input to the (G) terminal of the control section.
As is well known, a modulator (balanced modulator) is a dual-dynamic amplifier, and has a differential signal input section and a differential control signal input section. A good signal applied to the signal input section is output with its amplification degree changed according to the difference in potential applied to terminals (G) and (C) of the control signal input section. The carrier color signal Ec before correction is input to the signal input section of the balanced modulator clothing. On the other hand, the reference potential Esl is input to the (to) terminal of the control signal input section. Ea is variable, and when E is not transmitted, that is, when E- is input to the (G) terminal of the other control signal input, the signal gain is 1.
choose as desired. Therefore, when EB is not input, the uncorrected carrier color signal Ec is outputted as the output of the balanced modulator BM. Then, when E(,) is input, the amplified corrected carrier color signal Ec' is output according to the magnitude of EGl, and 116 at this time Ee * E
The amplitude of g *Ee' is 1Ec1. IEgl, IEc
'l, then IE♂1 is lEc'l = 1+a・lEgllE♂1a: O is a constant. To determine how much the signal He is amplified with respect to the magnitude of EQ, adjust the gain of video amplifier VA3. It can also be determined by K.

In this way, when the input color signal is green, and only at that time, 9
, the carrier color signal He is amplified. In this way, the green signal G is amplified (or decreased).

As described above, according to the present invention, the green signal can be amplified independently without affecting other color signals and luminance signals, so it is possible to obtain an output color containing a desired level of green signal. In addition, since the green signal is obtained from the red signal, background signal, and brightness signal that normally exist in the NTSC input signal, the invention can be implemented with a simple circuit configuration. This corrects the input color signal obtained from the image pickup tube or camera board, but it is also possible to detect the green signal level from the NTSC signal input from the antenna and amplify only the green signal. is possible.

Further, in this embodiment, an NTSC signal is obtained, but it can also be implemented in a demodulation circuit that demodulates other color television signals or a color television signal such as an NTSC signal to obtain a reproduced primary color signal. Also, for video amplifiers and humparators, whether it is a simple amplifier or a differential type amplifier, the same thing can be done by using a FET switch, etc. as a switch to turn the OEQ on and off, or by changing the level on one side of the differential amplifier. It can also be assembled by

Furthermore, the balanced modulator may simply be an amplifier with variable amplification.

[Brief explanation of the drawing]

3 is a detailed block diagram of a part of FIG. 2, and FIG. 4 is a detailed circuit diagram of FIG. 3. In the figure, 1 is a camera tube, 3 is a preamplifier, 5 is a process circuit, 7Fi encoder, 9Fi correction signal creation circuit, 1
1 is a correction circuit, VAI to VA3 are video amplifiers, OPI
, OF2 is 7V-1, Tri to Tr7 are transistors, and BM is a balanced modulator. Applicant Canon Co., Ltd.

Claims (1)

[Claims] means for obtaining three signals, a luminance signal, a red signal, and a blue signal from an input color signal; a means for obtaining an output color signal from the three signals; a detection means for detecting the level of the green signal from the three signals; A color video signal capable of enhancing or reducing a green signal component by having means for adjusting the amplitude of the output color signal when the level difference between the red signal and the blue signal is less than a predetermined level by the output of the means. Processing equipment.