JPH0787501A - Video camera - Google Patents

Abstract

PURPOSE:To prevent unnecessary color shading to surely eliminate a false color in the high-luminance part by providing a color separation block, an AGC amplification part for color processing which detects the peak of an image pickup output signal, and a high-luminance false color suppression part which suppresses the color signal in the high-luminance part. CONSTITUTION:Conventional average detection is not adopted but peak detection is adopted in ACC amplification, and AGC amplification is so performed that the level of the high-luminance part is fixed with respect to a color signal. Consequently, the level of the whole of a picture is unnecessarily raised and the level of the part other than a spot light is not raised even if a spot light is thrown to the dark picture by panning a camera. When a false color suppression signal generated, color component signals of filters 22 and 23 after AGC amplification which are synthesized with the image pickup output before AGC amplification, which passes a clam circuit 2, by addition are given to a highluminance cause color suppression part 31, and delay circuits 44 and 45 are used to make time bases of two signals coincide with each other, and they are added through resistors 46 and 47 for level adjustment to obtain the false color suppression signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera for color photographing using a CCD solid-state image pickup device (CCD imager).

[0002]

2. Description of the Related Art Conventionally, in a CCD imager of this type of video camera, a phenomenon occurs in which the image pickup output of a high brightness portion on the verge of saturation is colored with a false color (false color). This is C
When the color filter of the CD imager is saturated in the high-luminance portion, the linearity of the color signal is deteriorated, and for example, only the green component of the image pickup output is not saturated due to this deterioration. As a result, the image pickup output is not white but is green. Because it is colored.

To eliminate the false color in the high-luminance portion and correct it to a white state is usually called high-luminance false color suppression. The signal used for the high-luminance false color suppression signal is called a high-luminance false color suppression signal.

A conventional video camera for suppressing high-luminance pseudo-color is constructed as shown in FIG. 2, and after the unnecessary noise is removed by the correlated double sampling circuit 1 from the signal of the image pickup output of the CCD imager, It is supplied in parallel to the luminance separation block 3 and the color separation block 4 via the clamp circuit 2.

The image pickup output signal supplied to the luminance separation block 3 is AGC-amplified by the AGC amplifier 6 of the luminance processing AGC section 5, and then the color carrier component is removed by the low-pass filter 7 to obtain the luminance component. The signals are separated and extracted.

The signal of the brightness component obtained by this separation and extraction is supplied from the filter 7 to the subsequent circuit section as a brightness signal of the image output and, at the same time, to form the gain control signal of the AGC, the resistor 8 and the capacitor 9 are connected. It is supplied to a calculator 11 for error integration provided in the feedback path of the AGC section 5 via a noise removal filter and an input resistor 10.

A signal of a brightness reference value formed by dividing the power supply voltage of the power supply terminal 12 by the variable resistor 13 is supplied to the arithmetic unit 11 via the input resistor 14. The arithmetic unit 11 forms an integrator together with the time constant resistor 15 and the capacitor 16 provided in parallel between the input and output terminals, and the luminance signal separated and extracted from the luminance reference value signal as a reference. The error between and is integrated, and the luminance signal of the imaging output is averaged and detected.

By this average detection, a luminance AGC signal that changes according to the deviation of the average luminance of the image pickup output from the set value (luminance reference value) is formed, and this signal is gain-controlled by the AGC amplifier 6 via the AGC circuit 17. The signal is fed back as a signal, and the AGC amplification of the amplifier 6 is feedback-controlled.

By this control, the luminance signal output from the filter 7 is AGC-amplified by the average detection method so that the average luminance becomes constant. On the other hand, the signal of the imaging output supplied to the color separation block 4 is the AG of the color processing AGC unit 18.
After being AGC-amplified by the C amplifier 19, the sample-hold circuits 20 and 21 and the low-pass filters 22 and 23 perform filter processing, and two kinds (R-
Y, B-Y) color difference signals are separated and extracted.

At this time, the brightness AGC signal of the arithmetic unit 11 of the brightness processing AGC section 5 is passed through the AGC circuit 24 to the AGC circuit 24.
The signal is supplied to the amplifier 19, and the amplifier 19 operates by the same average detection method as the AGC amplifier 6 to amplify the color component signal by AGC.

Then, the output signals of the filters 22 and 23 are supplied to a color signal processing block 25, and this block 25
The color signals of three primary colors are formed by color signal processing such as signal addition / subtraction, modulation, and gamma correction, and the color signals are supplied to the subtraction circuit 27 of the high-luminance false color suppression unit 26.

Further, in order to perform the above-described high luminance false color suppression,
Image output signal of clamp circuit 2 and AGC of filter 7
The amplified luminance signal is added via the level adjusting resistors 28 and 29 of the high luminance pseudo color suppression unit 26, and the high luminance pseudo color suppression signal formed by this addition is supplied to the subtraction circuit 27.

The subtraction circuit 27 operates only when the high-luminance pseudo-color suppression signal is equal to or higher than a predetermined level corresponding to the saturation level of the color signal, and subtracts the high-luminance pseudo-color suppression signal from the output signal of the processing section 25. False colors in the high-brightness part of the image output are reduced, removed, suppressed, and erased. Then, the color signal in which the false color of the subtraction circuit 27 is suppressed is supplied to the subsequent circuit section.

By adjusting the levels of the resistors 28 and 29, for example, the signal of the image pickup output before AGC amplification via the clamp circuit 2 and the luminance signal after AGC amplification output from the filter 7 are in a level change range (span). Are corrected to the same value and added. Further, the high-luminance false color suppression signal is formed by adding the signal before AGC amplification and the signal after AGC amplification in order to surely eliminate the false color in the high-luminance portion regardless of the shooting conditions. is there.

That is, the following are conceivable causes of the false color in the high-luminance portion. Saturation of CCD imager color filters. Auto iris control, AGC transient fluctuation.

Furthermore, the following cases (a) and (a) can be considered as the transient fluctuation of. (A) When the spot light enters a dark screen due to the panning of the camera, the auto iris control is delayed, and the image output signal before AGC amplification becomes excessive due to the full opening of the iris, and the high brightness part is colored in a false color. To be done. (A) AGC is delayed when a brighter spot light enters a bright screen due to panning of the camera,
The image output signal before AGC amplification is AGC even if it is not too large.
The signal after amplification becomes excessive and the high-luminance portion is colored in a false color.

In order to eliminate the false color based on the above (1) and (2), A as a signal having a sufficient level for suppressing the false color is used.
The image pickup output signal before the GC amplification is necessary, and the erasing of the false color based on the above (1) and (2) requires the signal after the AGC amplification as a signal of a level sufficient for erasing the false color.

Therefore, in order to suppress and eliminate the false color due to both of the above causes, the signal of the imaging output before AGC amplification and the luminance signal after AGC amplification are added to form a high luminance pseudo color suppression signal. .

The signal of the image pickup output before AGC amplification and A
In some cases, instead of adding the luminance signal after the GC amplification, the one having the higher level of both signals is selected and the selected signal is set as the high luminance pseudo color suppression signal. Further, even if the image pickup output signal before AGC amplification and the luminance signal after AGC amplification are respectively set as high luminance pseudo color suppression signals, and both suppression signals are sequentially subtracted from the color signal, as a result, both suppression signals are obtained. It means that the one with a higher level suppresses the false color and erases it.

[0020]

In the case of the conventional video camera, the average detection of the luminance signal of the AGC section 5 is shared by the detection of the AGC amplification of the luminance signal and the chrominance signal, and the AGC amplification after the average detection is performed. The luminance signal is used to form a high luminance false color suppression signal.

In this case, the average detection level is set so as to secure an appropriate brightness even for a dark screen, and based on this setting, when spot light enters the dark screen due to panning of the camera, for example, it transits. The luminance signal after the AGC amplification rises even in a portion other than the spot light portion.

As a result, in the color signal after AGC amplification, even the originally normally colored portion other than the spot light turns into a high-luminance portion, and the coloring of these portions disappears due to the high-luminance false color suppression. There is a problem in that unnecessary high-luminance pseudo color suppression is performed, and the reproduced screen using the suppressed color signals becomes unnatural and unsightly. In order to prevent the above-mentioned unnecessary high luminance false color suppression, it is conceivable to change the AGC detection method of the luminance signal to the peak detection method, and to perform both AGC amplification of the luminance signal and the chrominance signal by the peak detection method.

In this case, when the spot light enters a dark screen, the AGC amplification is performed with the high-luminance portion of the spot light as a reference, so that the portion other than the spot light is carelessly changed to the high-luminance portion. Although it is prevented from tumbling, the AGC amplification of peak detection is applied to the luminance signal. Therefore, in so-called backlight photography, for example, a person in the central portion becomes too dark due to the luminance control based on the brightness of the peripheral portion. In addition, in such a case, even if the so-called backlight correction is performed, the effect is reduced and the effect is not sufficiently exerted, and there is a problem that good photographing cannot be performed. SUMMARY OF THE INVENTION It is an object of the present invention to prevent unnecessary color fading and reliably reduce and remove false colors in high-luminance portions without affecting the processing of luminance signals.

[0024]

In order to achieve the above-mentioned object, in the video camera of the present invention, in the case of claim 1, AGC amplification of peak detection is provided for the image output signal provided in the color separation block. The color processing AGC unit is provided, and the high-luminance pseudo-color suppressing unit that suppresses the color signal of the high-luminance portion by the addition signal of the image pickup output signal and the color component signal.

According to the present invention, the color processing AGC section provided in the color separation block for subjecting the image pickup output signal to the AGC amplification of the peak detection, and the image pickup output signal and the color component signal are large. And a high-luminance pseudo-color suppressing unit that suppresses the color signal of the high-luminance portion by the other signal.

[0026]

In the video camera of the present invention configured as described above, the AGC amplification of the peak detection of the color processing AGC unit is applied to the color signal regardless of the detection method of the AGC amplification of the luminance signal.

Further, the color signal based on the color component signal AGC-amplified by the color-processing AGC section is a high-luminance pseudo-color suppression to obtain a signal of an imaging output before AGC amplification and a color signal after AGC amplification of peak detection. Is added or the larger signal is used to suppress, reduce, and remove the false color in the high-luminance portion.

In this case, the chrominance signal is detected by the peak detection method without affecting the processing such as AGC amplification of the luminance signal.
Since it is GC-amplified, it does not cause a situation in which the subject becomes too dark in backlight photography, and does not interfere with the effect of backlight compensation, and when spotlight enters a dark screen due to camera panning or the like. It is possible to prevent unnecessary color fading and reliably suppress, reduce, and remove false colors in high-brightness areas.

[0029]

EXAMPLE One example will be described with reference to FIG. 1, the same symbols as those in FIG. 2 indicate the same or corresponding ones, and the points different from the conventional camera of FIG. 2 are the following points (i) and (ii). (I) The color separation block 4 is provided with a peak detection type color processing AGC section 30 which is separate from the luminance processing AGC section 5. (Ii) Instead of the suppression unit 26 of FIG. 1, a signal of the imaging output before the AGC amplification of the clamp circuit 2 and the signal of the color component after the AGC amplification of the peak detection are added to form a high luminance pseudo color suppression signal. The point that the high-luminance false color suppression unit 31 is provided.

Then, the color processing AGC unit 30 amplifies the image pickup output signal of the clamp circuit 2 by the AGC amplifier 32 and supplies it to the sample hold circuits 20 and 21, and the color components separated and extracted by the low pass filters 22 and 23. Signals are added and combined through resistors 33 and 34 to form a signal of a color component equivalent to the luminance signal (combined color signal).

Further, this composite color signal is supplied to the operational amplifier 38 via the resistor 35, the noise removing filter of the capacitor 36 and the input resistor 37. Further, the signal of the color reference value formed by dividing the power source voltage of the power source terminal 39 by the variable resistor 40 is passed through the resistor 48 to the operational amplifier 38.
Supply to.

The operational amplifier 38 forms a peak detection circuit together with the time constant resistor 41 and the capacitor 42 between the input and output terminals, and performs peak detection of the error signal between the composite color signal and the color reference value signal. The signal of the detection output is supplied to the AGC amplifier 32 via the AGC circuit 43, and the amplifier 3
The AGC amplification of 2 is feedback-controlled.

Based on this control, the AGC section 30 peak-detects the color signal of the imaging output, amplifies it so that the peak value is kept constant, and the sample-hold circuit 20 in the next stage,
21.

In this case, since the peak detection AGC amplification is used instead of the average detection AGC amplification of the conventional apparatus, the color signal is AGC amplified so that the level of the high-luminance portion becomes constant. Therefore, when the spotlight enters a dark screen due to panning of the camera or the like, the level of the entire screen does not unnecessarily rise, and the portion other than the spotlight does not reach a high level.

Next, in order to form a high-luminance false color suppression signal, the AGC-amplified filters 22 and 2 that are added and synthesized with the signal of the imaging output before the AGC amplification via the clamp circuit 2 are formed.
The signals of the three color components are supplied to the high-luminance pseudo-color suppressor 31, and both signals are adjusted by delay circuits 44 and 45 so that their time axes coincide with each other, and then via resistors 46 and 47 for level adjustment. The high luminance false color suppression signal is formed by the addition. The resistors 46 and 47 are the resistors 28 and
By adjusting the levels of the resistors 46 and 47, for example, the level change range (span) of the image output signal and the color component signal after AGC amplification are adjusted to the same level.

The high-luminance pseudo-color suppression signal is supplied to a subtracting circuit 48 corresponding to the subtracting circuit 27 of FIG. 2, and the subtracting circuit 48 outputs the high-luminance pseudo-color suppressing signal at a predetermined level corresponding to the saturation level of the color signal. Only in the above case, the high luminance false color suppression signal is subtracted from the color signal of the chroma signal processing block 25.

At this time, since the AGC-amplified signal forming the high-luminance pseudo-color suppression signal is a composite color signal that is AGC-amplified by the peak detection method, spot light may enter a dark screen due to panning of the camera. At this time, that is, when the amount of AGC amplification is large and the signal level after AGC amplification is large and this signal effectively acts on suppression of false color, when the signal after AGC amplification of the conventional average detection method is used, As described above, the level of the entire screen does not rise, unnecessary high-luminance portions are not formed and their colors are not erased, and only the color components of the high-luminance portions colored in a false color by spot light are AGC.
It is suppressed by the amplified signal, and only the false color is suppressed and erased.

When a brighter spotlight enters the entire screen in a bright state, the AGC amplification amount is suppressed and small, and the signal level after AGC amplification in the high-luminance portion of the spotlight is not high. , The signal of the imaging output before AGC amplification becomes large, so that the false color of the high-luminance portion is surely reduced and removed by this signal and suppressed.

On the other hand, A for brightness processing of the brightness separation block 3
Since the GC unit 5 applies the AGC amplification of the average detection to the luminance signal, the AGC of the peak detection is used in so-called backlight photography.
The central object does not become too dark unlike when amplification is performed, and backlight correction and the like normally operate.

As is apparent from FIG. 1, the signal after AGC amplification used for the high luminance false color suppression signal is composed of the color component signal before gamma correction. This is because the level (gradation) of the high-luminance portion is suppressed and reduced when the gamma correction is applied, and thus the false color suppression cannot be properly performed when the signal after the gamma correction is used.

By the way, in the above-mentioned embodiment, the signal obtained by adding the image pickup output signal before AGC amplification and the composite color signal after AGC amplification is used as the high luminance false color suppression signal, and this signal is subtracted from the color signal after AGC amplification. Although the false color is suppressed and erased by, for example, a signal selection gate is provided at the stage subsequent to the resistors 46 and 47 in FIG. 1, and the one having a higher level between the image pickup output signal before AGC amplification and the composite color signal after AGC amplification is selected. The same effect can be obtained by selecting a high-luminance false color suppression signal and subtracting this signal from the color signal after AGC amplification.

A column circuit of two subtraction circuits is provided at the position of the subtraction circuit 48 in FIG. 1, and a signal of the image pickup output before AGC amplification via the resistor 46 and a composite color after AGC amplification via the resistor 47. The signals may be separately supplied to both the subtraction circuits of the column circuit as high-luminance pseudo-color suppression signals. In this case as well, the false color of the high-luminance portion of the color signal after AGC amplification is the image output signal and the AGC amplified signal. It is suppressed and reduced or eliminated by the one having a higher level with the subsequent composite color signal. Further, it is needless to say that the present invention can be applied to the case where the detection method of AGC amplification of the luminance signal is different from that of the embodiment.

[0043]

Since the present invention is configured as described above, it has the following effects. Regardless of the detection method of AGC amplification of the luminance signal, the color processing AG is added to the color signal.
The AGC amplification of the peak detection of the C section 30 is performed, and the color signal AGC-amplified by the AGC section 30 is processed by the high-luminance false color suppression section 31 into the image output signal before the AGC amplification and the color signal after the AGC amplification of the peak detection. The false color in the high-luminance portion is suppressed and reduced or eliminated by using the addition signal of the component signal or the larger signal.

Therefore, the chrominance signal is AGC-amplified by the peak detection method without affecting the processing such as AGC amplification of the luminance signal, and the subject does not become too dark in backlight photography, and moreover, Prevents unnecessary color fading when spotlight enters a dark screen due to camera panning, etc. without hindering the effect of backlight compensation, and reliably suppresses, reduces, and eliminates false colors in high-brightness areas. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a video camera of the present invention.

FIG. 2 is a block diagram of a conventional example.

[Explanation of symbols]

 3 Luminance Separation Block 4 Color Separation Block 30 AGC Unit for Color Processing 31 High Luminance False Color Suppression Unit

[Procedure amendment]

[Submission date] November 30, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006] signal of the luminance component obtained by the separation extraction is supplied as the luminance signal from the image output to a subsequent circuit portion from the filter 7, in order to form a gain control signal AGC, resistance 8, the capacitor 9 Average detection,
It is supplied to the error amplifying arithmetic unit 11 provided in the feedback path of the AGC unit 5 via the input resistor 10.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

Further, the voltage of dividing brightness reference value that is formed by the variable resistor 13 to the power supply voltage of the power supply terminal 12 is supplied to the calculator 11 via the resistor 14 for input. The computing unit 11 includes a resistor 15 provided between the input and output terminals,
An inverting amplifier is formed by the capacitor 16 and the brightness reference value
And a voltage reference amplifies the difference between the voltage and the separation extracted luminance signal, averaging detects brightness signal of the image pickup output.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

[0029]

EXAMPLE One example will be described with reference to FIG. 1, the same symbols as those in FIG. 2 indicate the same or corresponding ones, and the points different from the conventional camera of FIG. 2 are the following points (i) and (ii). (I) The color separation block 4 is provided with a peak detection type color processing AGC section 30 which is separate from the luminance processing AGC section 5. (Ii) Instead of the suppression unit 26 of FIG. 2 , a signal of the imaging output before the AGC amplification of the clamp circuit 2 and the signal of the color component after the AGC amplification of the peak detection are added to form a high luminance pseudo color suppression signal. The point that the high-luminance false color suppression unit 31 is provided.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

Further, this combined color signal is subjected to peak detection by the resistor 35 and the capacitor 36, and is supplied to the operational amplifier 38 via the input resistor 37. Further, the color reference value signal formed by dividing the power supply voltage of the power supply terminal 39 by the variable resistor 40 is supplied to the operational amplifier 38 via the resistor 48.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

The operational amplifier 38 is connected between the input and output terminals .
Resistor 41, forms an inverting amplifier with a capacitor 42, the error between the voltage of the composite color signal and a color reference value amplified, AGC amplifier 32 a signal of the detection output via the AGC circuit 43
The AGC amplification of the amplifier 32 is feedback-controlled.

Claims (2)

[Claims] 1. A color imaging output signal of a CCD solid-state imaging device is subjected to AGC by a luminance separation block and a color separation block.
Amplification and filtering are performed to separate and extract the luminance component and color component signals, and the color signal of the high luminance portion of the imaging output based on the color component signal is suppressed to reduce or remove the false color of the high luminance portion. In the video camera, the color processing AGC unit provided in the color separation block for performing AGC amplification of peak detection on the signal of the imaging output, and the addition signal of the signal of the imaging output and the signal of the color component A video camera, comprising: a high-luminance pseudo-color suppressing unit that suppresses a color signal in a high-luminance portion. 2. A color imaging output signal of a CCD solid-state imaging device is subjected to AGC by a luminance separation block and a color separation block.
Amplification and filtering are performed to separate and extract the luminance component and color component signals, and the color signal of the high luminance portion of the imaging output based on the color component signal is suppressed to reduce or remove the false color of the high luminance portion. In the video camera, a color processing AGC unit is provided in the color separation block and performs AGC amplification of peak detection on the image output signal, and a larger signal of the image output signal and the color component signal. And a high-luminance pseudo-color suppressing unit that suppresses the color signal of the high-luminance portion.