JPS6374388A - Video signal processing device - Google Patents

Abstract

PURPOSE:To prevent occurrence of change in the degree of color saturation of another signal by change in burst amplitude of one signal by controlling amplitude of carrier chrominance signal of a slave picture according to amplitude of burst signals of a master picture. CONSTITUTION:The gain of a variable gain amplifier 29 is so controlled that when amplitude of burst signals of master picture signals is larger, amplitude of carrier chrominance signals of adder circuit 15 output is made large, and conversely, when amplitude of burst signals of master picture signals is small, amplitude of carrier chrominance signals of slave picture signals is made small. As slave picture signals are supplied to an ACC circuit, amplitude of burst signals is controlled to become a specified level. Thereby, amplitude ratio of burst signals and carrier chrominance signals in the ACC circuit 4 output and amplitude ratio of burst signals of master picture signals and carrier chrominance signal of slave picture signals become equal, and the degree of color saturation does not change.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention is a method for reducing or enlarging a screen by digitally processing a video signal in a VTR, a color television receiver, etc., and transmitting a plurality of color television signals. The present invention relates to a video processing device for compositing.

(b) Prior art Figure 2 shows an example of conventional technology. Input from input terminal i1+
The first composite video signal is separated into a luminance signal (Y+) and a chromaticity signal by a low pass filter (21) and a high band pass filter (3).The chromaticity signal is separated by an ACO circuit (4). , are demodulated into a red difference signal [R-Y], a blue difference signal (B-Y) in a machine-controlled n-color demodulation circuit (5) in which the amplitude of the burst signal is constant.A luminance signal, a red difference signal, The blue color difference signal is time-divided by the multiplexer (6) and
/D Digitized by converter (7) and controlled by control circuit (8)
, field memory (9) performs screen reduction or enlargement processing. The reduced or enlarged digital image signal is sent to a D/A converter (II (11) (13), where it is sent to an analog luminance signal (G), a red difference signal (R-Y), and a blue difference signal CB-. Y).The color difference signal is
vCxO circuit [voltage control crystal excavation circuit] (231 and 9
The color subcarriers sent from the 0 degree phase shift circuit (241) are balanced-modulated, and their respective outputs are combined by an adder circuit α9 to form a carrier color signal.

The carrier chrominance signal is combined with the luminance signal by an adder (161) and outputted from the terminal (2) via the switch to a composite video signal that has been reduced or expanded.The composite video signal is output as: This is because this device is configured to share the special playback field memory in the VTR.The switch switches to the iat side only during the period when it is desired to output a reduced or enlarged image, and during other periods. Flip the n switch to the (b) side (outputs the signal from 181).

The input/output signal waveform of switch 4 becomes as shown in FIG. 5 when the color par signal is input to terminals ill and - (one horizontal period is shown). (11 is the waveform input to the (bl of the switch (251). When the screen is reduced, it is input to the (aj) of the switch; in the figure, it is reduced to half of the TV screen. This is an example in which a small signal is output to the right half of the screen.
”, it switches to the lal side. (IVI is
This is the output waveform of switch 4 when the screen is small. Then (yl
is the waveform input to the switch (ml) when the screen is enlarged; the figure shows an example in which the screen is doubled in the horizontal direction.

(Vll is a control signal for the switch like +1g+, and the waveform shown in Fig. is the switch (bl)
This is the signal of K input n signals.

On the other hand, the terminal αη in FIG. 2g1 is the input terminal for the second composite video signal, and the switch 081Fi switches the video signal. For example, if the drawing reduction switch (181) is turned to the LAL side, the screen displayed on the TV due to the output from the terminal will be as shown in Figure 4.
The reduced first video signal is synthesized with the normal first video signal (signal input from terminal (1)). (If it falls on the BL side, the first video signal (for example, the signal from the tuner) that has been reduced to the normal second video signal (for example, the playback signal of a VTR) is synthesized at the moment of hitting as shown in Figure 3. In addition, the (branch) part in Figure 4 is the main screen,
The part is called the child screen. Below, switch U (cl
The signal outputted from the terminal +I+ is called the main screen gM, and the signal input from the terminal +I+ and digitally processed is called the child screen signal.

Next, the parts 0 to ■ in FIG. 1 are circuits that create color subcarriers synchronized with the burst signal in the main screen signal. The horizontal synchronization signal is separated from the main screen signal by the synchronization branch circuit (19), and the horizontal synchronization signal becomes a burst gate pulse by the delay circuit. The burst gate circuit 12) J is a burst signal only from the main screen signal. The extracted burst signal and v a x
A phase detection circuit performs phase detection using the output of the oc231, and the error voltage is used to create a color subcarrier synchronized with the burst of the main screen signal controlled by the υvcxo(231).

The above is an explanation of the circuit shown in FIG. Possible drawbacks of this circuit are as follows. The color saturation of the child screen output from the terminal 12θ and displayed on the color TV screen is controlled by the amplitude of the burst signal that is 8 times the main screen signal.
If the burst level of the main screen signal is too large, the colors of the child screen will appear pale; on the other hand, if the burst level is small, the colors of the child screen will appear dark. In other words, even if the signal input to lal of switch ■ in Figure 1 is exactly the same, if the burst level of the main screen signal input to (bl of switch Ω changes), The color intensity on the screen changes.

A processing device for reducing and enlarging a color television signal as shown in FIG. 1 is disclosed in, for example, Japanese Patent Laid-Open No. 55-34510.

In addition, in Japanese Patent Application Laid-Open No. 60-172891, A of the main screen
A configuration is shown in which the operation of the ABL circuit of the television receiver is switched in the sub-screen portion in order to prevent changes in the brightness of the sub-screen due to PL changes.

Also, a configuration in which the main screen signal is supplied to the AOO circuit is conceivable, but it would be necessary to separate the luminance and color signals, which would complicate the configuration and degrade the image quality.

→ Problem to be solved by the invention In other words, in the prior art, when the screen of one video signal is reduced or enlarged and combined with another video signal, the color saturation of the child screen is lower than that of the main screen. There was a problem in that it changed depending on the burst signal level.

#:,,1 Means for Solving the Problems In the present invention, the color television signal of the parent screen, that is, the burst signal of the sub screen is determined according to the amplitude of the burst signal of the (first) color television signal in which the burst signal is left. controlling the amplitude of the carrier color signal of the (second) color television signal.

(E) Function: The amplitude of the carrier color signal of the sub-screen is controlled according to the amplitude of the burst signal of the main screen. In other words, if the burst signal amplitude 1 of the main screen is small, the amplitude of the carrier color signal is controlled according to the amplitude of the burst signal of the main screen. There is no fear that the color saturation of the child screen will change by making it smaller and, in the opposite case, making it larger.

(F) Embodiment FIG. 1 shows a block diagram of an embodiment of the present invention (an embodiment used in a VTR). Components that are the same as those in FIG. 2 are given the same figure numbers.

The newly added configuration includes a burst gate (211 output is applied) peak detection circuit to which the burst signal of the main screen signal is input, a smoothing circuit (to) which inputs the output of this peak detection circuit, and a smoothing circuit. (2) It is a variable gain amplifier whose gain is controlled by the output voltage. The carrier color signal from the adder circuit a9 is applied to this variable gain amplifier, which controls the amplitude of the carrier color signal of the child screen signal according to the amplitude of the burst signal of the main screen signal, and performs D/A conversion. (
This will be added to the once signal from 1■.

The gain control of the variable gain amplifier ■ increases the amplitude of the carrier color signal output from the adder circuit α when the amplitude of the burst signal of the main screen signal is large, and conversely, when the amplitude of the burst signal of the main screen signal is small. is performed so as to reduce the amplitude of the carrier color signal of the small screen signal. This is to prevent the color saturation of the child screen signal from changing even if the amplitude of the burst signal of the main screen changes.

That is, since the small screen signal is supplied to the CC circuit (4)K, the amplitude of the burst signal is controlled to a certain predetermined level. Therefore, if the amplitude of the burst signal of the main screen signal from the burst game (211) is different from the predetermined level, the gain of the variable gain amplifier is changed according to the ratio. )
Assuming that the burst amplitude of the output is 1, if the burst amplitude of the output of the burst gate is 0.5, the gain of the variable gain amplifier may be set to A when the burst amplitude of the burst gate QD output is 1.

As a result, the amplitude ratio of the burst signal and the carrier color signal at the output of the AOO circuit (4) becomes the same as the amplitude ratio of the burst signal of the main screen signal and the carrier color signal of the child screen signal, and the color saturation changes. do not.

In addition to the above embodiments, automatic gain control circuits are provided between the D/A converter (111) and the balanced modulator (13), and between the D/A converter a21 and the balanced modulator (141). , the amplitude of the sub-screen color difference signal may be controlled.Furthermore, the output of the smoothing circuit (to) may be used to control the CC circuit so that the burst amplitude of the main screen signal and the burst amplitude of the sub-screen signal are the same. You may also do so.

(G1) Effects of the Invention As described above, according to the present invention, when two color television signals are combined, a change in the burst amplitude of one signal causes a change in the color saturation of the other signal. This is effective because it can be prevented with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of a conventional example, and FIGS. 3 and 4 are explanatory diagrams showing picture-in-picture operations.

Claims (1)

[Claims] (1) An image in which the burst signal of the first color television signal is left, the burst signal of the second color television signal is removed, and the first and second color television signals are combined. A video signal processing device comprising means for controlling the amplitude of a carrier color signal of the second color television signal in accordance with the burst signal amplitude of the first color television signal.