JPH0516782Y2 - - Google Patents

Description

Detailed Description of the Invention Technical Field The present invention relates to a circuit for special effects in a video camera, and more particularly to a circuit for a so-called defocusing effect (soft focus effect) for making part of an image a soft, out-of-focus image.

<Prior art> In general, when shooting special effects with a video camera, for example, as shown in Fig. 5, the central part of the screen A is set to a hard area with normal sharpness (display area B shown by a solid line), and the peripheral part is focused. The defocusing effect that creates a soft blur area (display area C indicated by the broken line) is as follows:
It is often used to express a fantastical image. In order to create such a deffocusing effect, conventionally a special effect filter is attached to the lens system, but this method of adjusting the optical system does not allow for the creation of special effects. It is difficult to freely set the area on the screen to be used and its degree.
The drawback is that it can only produce fixed image effects.

<Purpose of the invention> The present invention was made in view of the above points, and its purpose is to enable special effects to be created arbitrarily by signal processing of a circuit system rather than an optical system. shall be.

<Configuration of the invention> In order to achieve the above-mentioned object, the invention provides a gain control signal forming circuit that forms a gain control signal for varying the sharpness in a screen based on a horizontal drive signal and a vertical drive signal. a separation circuit that separates the luminance signal into a low-frequency luminance signal component and a high-frequency luminance signal component; an amplifier circuit that amplifies the high-frequency luminance signal component from the separation circuit in accordance with the gain control signal; A mixing circuit is provided for mixing the output of the circuit and the low-band luminance signal component from the separation circuit.

According to the above configuration, by controlling the gain of the amplification circuit that amplifies the high-frequency luminance signal component, it is possible to freely create special effects by varying the sharpness in the screen in a desired area. Become.

<Embodiments> Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is a block diagram of one embodiment of the present invention, and in the same figure, the signal waveforms of each part are also shown. The special effect circuit of this embodiment comprises a gain control signal forming circuit 1 which forms a gain control signal for making the sharpness in one frame of the screen different according to each display area in the screen based on a horizontal drive signal (HD) and a vertical drive signal (VD), and a separation circuit 2 which separates a luminance signal Y1 into a low-frequency luminance signal component Y2 and a high-frequency luminance signal component Y3.
and the high-frequency luminance signal component Y3 from the separation circuit 2.
in accordance with the gain control signal, and a mixer circuit 4 for mixing the output of the DC gain control amplifier 3 with the low-frequency luminance signal component Y2 from the separation circuit 2.

The gain control signal forming circuit 1 is a circuit for forming a gain control signal for determining the area on the screen where a special effect is created or the degree thereof, and in this embodiment, it is the same as that explained in FIG. A gain control signal is created to make the center of the screen a hard area with normal sharpness, and the peripheral area a soft area with dull sharpness.

That is, this gain control signal forming circuit 1 integrates a horizontal drive signal and a vertical drive signal, respectively, and forms and outputs a sawtooth wave with a horizontal period (1H period) and a vertical period (1V period). circuits 5 and 6, and third and fourth integration circuits 7 and 8 that integrate the outputs of both integration circuits 5 and 6 to form and output horizontal and vertical period parabolic waves, and both integration circuits 7 and 8. the first, which attenuates the output respectively;
A first differential amplifier 1 to which the outputs of the second attenuators 9 and 10, the third integration circuit 7, and the first attenuator 9 are given.
1, a second differential amplifier 12 to which the outputs of the fourth integrating circuit 8 and the second attenuator 10 are applied, and a mixing circuit 13 that mixes the outputs of both the differential amplifiers 11 and 12.

Therefore, according to the above configuration, the first differential amplifier 11 outputs a parabolic waveform with a horizontal period (1H), and the second differential amplifier 12 outputs a parabolic waveform with a vertical period (1V). are obtained, both are superimposed in the mixing circuit 13, and further,
The gain control signal is superimposed on DC ₀ , which is the average value of the DC bias of the DC gain control amplifier 3, through the CR coupling section 18, as shown in FIG.
It is applied to the DC gain control amplifier 3 and its gain is controlled. The level difference x between the lowest value (min) and highest value (max) of the gain control signal in Figure 1 is DC
This corresponds to the difference between the minimum gain and maximum gain control voltages of the gain control amplifier 3.

The separation circuit 2 includes a buffer circuit 14 and a broadband first circuit that passes high and low frequency components of the luminance signal.
Low-pass filter 15 and low-frequency component Y of the luminance signal
A second low-pass filter 16 that allows only 2 to pass through.
and a differential amplifier 17 that outputs a high-frequency luminance signal component Y3 as the difference between the outputs of both low-pass filters 15 and 16. 1st low pass filter 1
5, the vertical axis represents the attenuation amount, and the horizontal axis represents the frequency.
As shown in FIG.
passes luminance signal components lower than frequency b. Therefore, from the differential amplifier 17, the second
Only the high-frequency luminance signal component Y3 shown in FIG. B is output. The frequency a is, for example, 3.5 to 4.0MHz, and the frequency b is, for example, 1.5MHz.
~2.0MHz.

The high-frequency luminance signal component Y3 from the separation circuit 2 is
The DC gain control amplifier 3 amplifies the signal according to the gain control signal. That is, control is performed so that the gain is maximum at the center of the screen and is minimum at the four corners of the top, bottom, left, and right of the screen. The output from the DC gain control amplifier 3 is mixed with the low frequency luminance signal component Y2 provided via the buffer circuit 19 and output.

3 and 4 respectively show the levels of luminance signal components in screen A and its respective parts a, b, and c. Figure 4A shows the center part a of the screen,
FIG. 4B shows the level of the luminance signal component at the center part b of each side of the screen, and FIG. 4C shows the level of the luminance signal component at the four corners c of the screen.

As shown in Figures 3 and 4, the central part a of the screen has normal sharpness because there is no attenuation of signal components, and the peripheral parts b and c have attenuation and therefore have poor sharpness. It becomes a dull soft area.

In this way, the high-frequency luminance signal component Y3 is amplified.
By controlling the gain of the DC gain control amplifier 3, it is possible to create a defocusing effect by forming hard areas and soft areas in the screen.

In the above embodiment, the central part of the screen is a hard area with normal sharpness, and the peripheral part is a soft area, but since the setting of this area is arbitrary, other embodiments of the present invention can be used. Alternatively, the inputs of the first and second differential amplifiers 11 and 12 may be reversed to invert the parabolic waveform, thereby making the central part of the screen a soft area and the peripheral part a hard area. . Furthermore, since the degree of sharpness is arbitrary, a sawtooth wave may be used instead of a parabolic wave as the gain control signal. That is, in the present invention, by arbitrarily controlling the gain of the DC gain control amplifier 3, it is possible to arbitrarily set the area or degree of special effects on the screen.

<Effects of the Invention> As described above, the present invention includes a gain control signal forming circuit that forms a gain control signal for varying the sharpness in a screen based on a horizontal drive signal and a vertical drive signal, and a separation circuit that separates a signal into a low-range luminance signal component and a high-range luminance signal component; an amplifier circuit that amplifies the high-range luminance signal component from the separation circuit in accordance with the gain control signal; and an output of the amplifier circuit. and a mixing circuit that mixes the low-range luminance signal component from the separation circuit, so by controlling the gain of the amplifier circuit, the sharpness in the screen can be varied to freely create special effects. It becomes possible to take out.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention;
Figure 3 shows the band of the luminance signal component, Figure 3 shows the screen, Figure 4 shows the level of the luminance signal component in each part of the screen in Figure 3, and Figure 5 shows the defocusing effect. FIG. 1... Gain control signal forming circuit, 2... Separation circuit, 3... DC gain control amplifier, 4... Mixing circuit.

Claims (1)

[Claims for Utility Model Registration] (1) A gain control signal forming circuit that forms a gain control signal for varying the sharpness in a screen based on a horizontal drive signal and a vertical drive signal; a separation circuit that separates a luminance signal component and a high-frequency luminance signal component; an amplifier circuit that amplifies the high-frequency luminance signal component from this separation circuit in accordance with the gain control signal; and an output of this amplifier circuit and the separation circuit. A special effects circuit for a video camera, comprising: a mixing circuit that mixes a low-frequency luminance signal component from a video camera. (2) The gain control signal forming circuit includes first and second integrating circuits that respectively integrate a horizontal drive signal and a vertical drive signal to form a sawtooth wave, and a circuit that integrates the sawtooth wave of each integration circuit. third and fourth integrating circuits that form a parabolic wave, and first and second integrating circuits that attenuate the outputs of the third and fourth integrating circuits, respectively.
an attenuator, and a first differential amplifier that outputs a difference signal between the output of the third integrating circuit and the output of the first attenuator;
A second differential amplifier outputs a difference signal between the output of the fourth integrator and the second attenuator, and a mixing circuit mixes the outputs of both differential amplifiers, and the separation circuit includes a narrow-band low-pass filter. and a wideband low-pass filter, and a differential amplifier that separates and outputs the high-frequency luminance signal component from the outputs of both low-pass filters. circuit.