JPS6329345Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color video camera, and more particularly to a false color erasing circuit that neutralizes false color signals occurring at vertical edges of photographed images.

In recent years, with the rapid development of semiconductor technology, the imaging elements of color television cameras have also been solid-stated. In this case, in a color camera using a solid-state image pickup plate, a Bayer array mosaic filter (color separation filter) as shown in FIG. 3 is used to achieve a single-plate configuration. Pixels of the solid-state imaging plate are arranged corresponding to each divided color filter in this mosaic filter. As shown in Fig. 4, this solid-state imaging plate is scanned alternately for each field using drive pulses with different sampling phases for each color, and the charges accumulated in each pixel are sequentially transferred through a mosaic filter. Color-separated video components are extracted from the image pickup plate as output signals. However, in this case, the R signal and B signal are taken out every other line, so if this continues, the R signal and B signal will be taken out over all lines.
It is not possible to extract the signal. Therefore, in such a single-chip color camera, for example, n
When you want to extract the R signal during the +1 line scanning period, take advantage of the fact that there is a vertical correlation between the R signal of the n line that precedes this n+1 line by 1H (1 horizontal scanning period), and extract the R signal that precedes this n+1 line by that amount. By using it with a delay, a continuous R signal is obtained over all lines. This also applies to the B signal.

However, in a color video camera that uses a color separation method that utilizes vertical periods, at the vertical edge of the subject where color information switches, colors that should not exist in the video signal portion corresponding to this edge are detected. There is a problem in that a false color signal indicating information is generated. For this reason, a color video camera using a mosaic filter, which has been commonly used in the past, uses a false color canceling circuit to suppress this false color signal.

FIG. 1 is a circuit diagram showing an example of a conventional false color erasing circuit, in which an edge portion of an image included in a video signal is first extracted as an edge detection signal A. In this case, the detection of the edge part is performed using, for example, a 1H delay line using a CCD element, and the signal GW is obtained by sampling and holding two lines of signals alternately for each pixel, and the signal G _W of one line is sampled and held for each pixel. signal
A method is used in which a signal _GL is extracted and a portion where the signal _GW and the signal _GL do not match is extracted. The edge detection signal A extracted in this way is supplied to a differential amplifier 2 via a low-pass filter 1, and its positive and negative differential outputs are added via an adder 5 via diodes 3 and 4. As a result, the edge detection signal is extracted with its polarity adjusted to one side.

On the other hand, the chroma signal C is supplied to the amplitude modulation circuit 7 via the 3.58MHz bandpass filter 6, and is amplitude modulated by the edge detection signal of the same polarity supplied from the adder 5 via the capacitor 8. Added. As a result, the amplitude of the chroma signal C at the point in time when the edge detection signal is generated is suppressed, so that this portion becomes an achromatic signal. The chroma signal outputted from the amplitude modulation circuit 7 after such processing is sent to the delay circuit 9 over one horizontal scanning period, and the delayed chroma signal and the undelayed chroma signal are added together in the adder 10. By doing so, the part that has been made colorless to suppress false color signals by the edge detection signal is added with the chroma signal of the adjacent horizontal scanning period and sent out as an averaged chroma signal C'. Prevents shedding.

However, in the false color elimination circuit with the above configuration, the level difference between the signal _GW and the signal _GL is extracted and used as an edge detection signal, but the signal _GW
If the level difference between the signal _GL and the edge part of the image is only at the edge part of the image and the level in the blanking part is the same, there will be no problem. However, in reality, both the signal _GW and the signal _GL are due to transfer noise of the CCD element and Due to fluctuations in the DC level, etc., the level of the blanking portion is equally lost. As a result, in the edge detection signal, unnecessary signals appear in parts other than the edge parts of the image, and even the burst signal is suppressed by the unnecessary signals included in the edge detection signal, and its level will change.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a false color eliminating circuit for a color video camera that does not cause level fluctuations to burst signals when suppressing false color signals.

To achieve this purpose, the present invention prevents the level fluctuation of the burst signal by interrupting the supply of the edge detection signal to the amplitude modulation circuit during the generation period of the composite blanking signal. . Hereinafter, the false color eliminating circuit for a color video camera according to the present invention will be described in detail with reference to the drawings.

FIG. 2 is a circuit diagram showing an embodiment of the false color eliminating circuit for a color video camera according to the present invention.
The same parts as in the figures are indicated using the same symbols. In the figure, 11 is a gate circuit provided between the adder 5 and the amplitude modulation circuit 7, and uses the composite blanking signal CB as an input signal for gate control.

In the circuit configured as described above, since the gate circuit 11 is normally open, when the adder 5 generates a pulsed edge detection signal indicating that an edge portion has been detected, this signal is The signal is supplied to the amplitude modulation circuit 7 via the gate circuit 11 as an amplitude control signal. As a result, the amplitude modulation circuit 7 suppresses and outputs the amplitude of the chroma signal C supplied via the bandpass filter 6 every time the edge detection signal is supplied, as in the case shown in FIG. As a result, all color signals including false color signals occurring at the edge portions of the image are erased, resulting in an achromatic color signal. The chroma signal subjected to such processing has its achromatic color portion preserved in the delay circuit 9 and adder 10, and is output as a chroma signal C' containing no false color signal.

Next, when the composite blanking signal CB is supplied to the gate circuit 11, the gate circuit 11 blocks the output of the adder 5, that is, the edge detection signal, from being supplied to the amplitude modulation circuit 7 during this period. do. Therefore, the amplitude modulation circuit 7 does not perform any amplitude control during the generation period of the composite blanking signal CB including the burst signal. As a result, even if the false color signal is suppressed, the burst signal will not be affected in any way.

In the above embodiment, a case was explained in which a composite blanking signal was used as a signal to control the gate circuit, but the present invention is not limited to this, and the present invention is not limited to this, but can also be applied to a composite blanking signal that occurs during video blanking and during a burst period. Needless to say, any signal may be used as long as it contains the signal.

As explained above, in the present invention, when applying amplitude modulation to a chroma signal to suppress it using an edge detection signal that detects an edge portion of a photographed image where false color occurs, the edge portion is suppressed during the generation period of the composite blanking signal. Since the detection signal is gated, fluctuations in the level of the burst signal are prevented and a clear image can be obtained, which is an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a conventional false color eliminating circuit for a color video camera, FIG. 2 is a circuit diagram showing an embodiment of a false color eliminating circuit for a color video camera according to the present invention, and FIG. FIG. 4 is a diagram showing an example of the arrangement of the mosaic filter according to the invention, and FIG. 4 is a diagram showing the phase relationship of sampling of drive pulses corresponding to the color arrangement of the mosaic filter. 1...Low pass filter, 2...Differential amplifier,
3, 4...Diode, 5, 10...Adder, 6
...bandpass filter, 7...amplitude modulation circuit,
9...Delay circuit.

Claims (1)

[Scope of utility model registration request] By detecting the edge portion of the video signal and generating an edge detection signal of the same polarity, and supplying this edge detection signal to the amplitude modulation circuit as an amplitude control signal, amplitude modulation is applied to the chroma signal to suppress false color signals. In the false color erasing circuit that outputs the chroma signal output from the amplitude modulation circuit after holding it and preventing color fading, a signal is applied to the input side of the amplitude control signal in the amplitude modulation circuit within the video blanking period. By providing a gate circuit which takes as a gate control input a pulse signal that is generated by a pulse signal and whose generation period includes a burst period, and by closing the gate circuit only during the generation period of the pulse signal, the burst signal is modulated and its level fluctuates. A false color erasing circuit for a color video camera is characterized in that it prevents.