JPH0320195B2 - - Google Patents
Info
- Publication number
- JPH0320195B2 JPH0320195B2 JP13264884A JP13264884A JPH0320195B2 JP H0320195 B2 JPH0320195 B2 JP H0320195B2 JP 13264884 A JP13264884 A JP 13264884A JP 13264884 A JP13264884 A JP 13264884A JP H0320195 B2 JPH0320195 B2 JP H0320195B2
- Authority
- JP
- Japan
- Prior art keywords
- color difference
- signal
- signals
- difference signals
- level
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000001514 detection method Methods 0.000 claims description 16
- 230000009467 reduction Effects 0.000 claims description 12
- 230000003321 amplification Effects 0.000 claims description 4
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 4
- 230000001629 suppression Effects 0.000 description 16
- 239000013598 vector Substances 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 3
- 230000002238 attenuated effect Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/64—Circuits for processing colour signals
- H04N9/646—Circuits for processing colour signals for image enhancement, e.g. vertical detail restoration, cross-colour elimination, contour correction, chrominance trapping filters
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Processing Of Color Television Signals (AREA)
Description
【発明の詳細な説明】
産業上の利用分野
本発明は色差信号の雑音低減回路に係り、色差
信号に含まれる小振幅の雑音を低減する色差信号
の雑音低減回路に関する。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color difference signal noise reduction circuit, and more particularly, to a color difference signal noise reduction circuit that reduces small amplitude noise contained in the color difference signal.
従来の技術
従来よりカラービデオカメラの映像出力回路等
に色差信号の雑音低減回路を設けたものがある。
第３図は従来の色差信号の雑音低減回路の一例を
示す。同図中、端子１，２夫々には色差信号Ｒ−
Ｙ，Ｂ−Ｙ夫々が入来し、端子３，４夫々には副
搬送波が入来する。Ｒ−Ｙ変調器５は副搬送波を
色差信号Ｒ−Ｙで平衡変調し、得られた被変調波
信号は利得制御回路６を介して混合器７に供給さ
れ、ここで利得制御回路９を介して供給されるＢ
−Ｙ変調器８よりの被変調波信号と加算混合され
てクロマ信号とされ、クロマ利得制御回路１０に
供給される。また、Ｒ−Ｙ変調器５、Ｂ−Ｙ変調
器８夫々よりの被変調波信号は検波器１１，１２
夫々で検波され、夫々の検波出力は混合器１３で
加算混合されて低彩度検出器１４に供給される。
低彩度検出器１４は上記検波出力が所定レベル以
下であるとき制御信号を発生してクロマ利得制御
回路１０に供給する。クロマ利得制御回路１０は
上記制御信号が供給されたときクロマ信号の振幅
抑圧を行なつて、低彩度抑圧されたクロマ信号が
端子１５より出力される。これによつてクロマ信
号は第４図の実線Ｉに囲まれる範囲で振幅抑圧さ
れ、無彩色に近い画面での色誤差を除去してい
る。2. Description of the Related Art Conventionally, some color video cameras have a video output circuit or the like provided with a color difference signal noise reduction circuit.
FIG. 3 shows an example of a conventional color difference signal noise reduction circuit. In the figure, terminals 1 and 2 each have a color difference signal R-
Y and B-Y come in, respectively, and subcarriers come in at terminals 3 and 4, respectively. The R-Y modulator 5 performs balanced modulation of the subcarrier with the color difference signal R-Y, and the obtained modulated wave signal is supplied to the mixer 7 via the gain control circuit 6, where it is modulated via the gain control circuit 9. B supplied by
- The signal is added and mixed with the modulated wave signal from the Y modulator 8 to form a chroma signal, which is supplied to the chroma gain control circuit 10. Further, the modulated wave signals from the R-Y modulator 5 and the B-Y modulator 8 are transmitted to the detectors 11 and 12, respectively.
The respective detection outputs are added and mixed in a mixer 13 and then supplied to a low saturation detector 14 .
The low saturation detector 14 generates a control signal and supplies it to the chroma gain control circuit 10 when the detected output is below a predetermined level. When supplied with the control signal, the chroma gain control circuit 10 suppresses the amplitude of the chroma signal, and outputs the chroma signal with low saturation suppression from the terminal 15. As a result, the amplitude of the chroma signal is suppressed within the range surrounded by the solid line I in FIG. 4, thereby eliminating color errors on a nearly achromatic screen.
発明が解決しようとする問題点
従来回路においては、クロマ信号の振幅抑圧を
行なつているため、色差信号Ｒ−Ｙ，Ｂ−Ｙ夫々
を独立に雑音低減することは不可能である。しか
し、例えばカラービデオカメラにおいては色差信
号Ｒ−Ｙ，Ｂ−Ｙ夫々は独立した過程で処理さ
れ、色差信号Ｒ−Ｙ，Ｂ−Ｙ夫々に含まれる雑音
の性質は異なつている。これらの雑音成分の大き
さが夫々異なる場合、従来回路では２つの雑音成
分を夫々最適に低減するようクロマ信号の利得制
御を行なうことはできないという問題点があつ
た。Problems to be Solved by the Invention In the conventional circuit, since the amplitude of the chroma signal is suppressed, it is impossible to independently reduce the noise of each of the color difference signals RY and BY. However, in a color video camera, for example, the color difference signals R-Y and B-Y are processed in independent processes, and the nature of the noise contained in each of the color difference signals R-Y and B-Y is different. When these noise components have different magnitudes, the conventional circuit has a problem in that it is not possible to control the gain of the chroma signal so as to optimally reduce each of the two noise components.
また、色差信号Ｒ−Ｙ，Ｂ−Ｙ夫々の成分が略
等しい色差ベクトルは第４図においてＲ−Ｙ軸、
Ｂ−Ｙ軸夫々に対して約45度の方向を持つが、従
来回路では実線Ｉに示す如く上記の色差ベクトル
に対して抑圧する範囲が狭く、その雑音低減効果
が低いという問題点があつた。更に、Ｒ−Ｙ変調
器５、Ｂ−Ｙ変調器８夫々に供給される副搬送波
のバランスがずれた場合、夫々の出力する被変調
波信号の直流オフセツトが発生するため、低彩度
検出器１４における所定レベル以下の低レベル信
号の検出が不安定になるという問題点があつた。 In addition, in FIG. 4, the color difference vectors in which the components of the color difference signals R-Y and B-Y are approximately equal are represented by the R-Y axis,
The direction is approximately 45 degrees with respect to the B and Y axes, but in the conventional circuit, as shown by the solid line I, the range in which the above color difference vector is suppressed is narrow, and the noise reduction effect is low. . Furthermore, if the balance of the subcarriers supplied to each of the R-Y modulator 5 and B-Y modulator 8 is shifted, a DC offset occurs in the modulated wave signals output from each, so that the low saturation detector There was a problem in that the detection of low level signals below a predetermined level in 14 became unstable.
そこで、本発明は、上記の問題点を解決した色
差信号の雑音低減回路を提供することを目的とす
る。 SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a color difference signal noise reduction circuit that solves the above problems.
問題点を解決するための手段及び作用
本発明は、入来する複数の色差信号夫々のレベ
ル検出を行なうレベル検出手段と、複数の色差信
号夫々のレベル検出信号のうち最大レベルのレベ
ル検出信号を選択する選択手段と、複数の色差信
号夫々に対応した複数の基準電位を有し複数の基
準電位夫々と選択されたレベル検出信号とを比較
して複数の色差信号夫々に対応した制御信号を生
成する比較手段と、複数の制御信号に応じて夫々
に対応する色差信号の振幅抑圧を行なう振幅制御
手段とより構成したものであり、第１図以下と共
にその一実施例につき説明する。Means and Effects for Solving Problems The present invention provides level detection means for detecting the level of each of the plurality of incoming color difference signals, and a level detection signal of the maximum level among the level detection signals of each of the plurality of color difference signals. a selection means for selecting, a plurality of reference potentials corresponding to each of the plurality of color difference signals, and comparing each of the plurality of reference potentials and the selected level detection signal to generate a control signal corresponding to each of the plurality of color difference signals; and amplitude control means for suppressing the amplitude of the corresponding color difference signals in accordance with a plurality of control signals, and one embodiment thereof will be described with reference to FIG. 1 and subsequent figures.
実施例
第１図は本発明回路の一実施例のブロツク系統
図を示す。同図中、端子２０ａには色差信号Ｒ−
Ｙが入来し、端子２０ｂには色差信号Ｂ−Ｙが入
来する。端子２０ａよりの色差信号Ｒ−Ｙはクラ
ンプ回路２１ａに供給されてクランプされた後、
リミツタ増幅器２２ａ、減衰器２３ａ、アナログ
スイツチ２４ａ夫々に供給される。リミツタ増幅
器２２ａはクランプ回路２１ａより供給される色
差信号Ｒ−Ｙのうちクランプ処理及び雑音低減処
理に不必要なレベルの大なる成分を除去して必要
な成分のみを増幅して出力する。リミツタ増幅器
２２ａの出力信号はクランプ回路２１ａに帰還さ
れ、クランプ回路２１ａは上記帰還に応じて入来
する色差信号Ｒ−Ｙのクランプを行ない直流オフ
セツトのない色差信号Ｒ−Ｙを出力する。またリ
ミツタ増幅器２２ａの出力信号は両波整流器２５
ａに供給され、ここで両波整流され、整流信号が
得られる。Embodiment FIG. 1 shows a block diagram of an embodiment of the circuit of the present invention. In the figure, the terminal 20a has a color difference signal R-
A color difference signal B-Y is input to the terminal 20b. After the color difference signal R-Y from the terminal 20a is supplied to the clamp circuit 21a and clamped,
The signal is supplied to a limiter amplifier 22a, an attenuator 23a, and an analog switch 24a, respectively. The limiter amplifier 22a removes large components of a level unnecessary for clamp processing and noise reduction processing from the color difference signal R-Y supplied from the clamp circuit 21a, and amplifies and outputs only the necessary components. The output signal of the limiter amplifier 22a is fed back to the clamp circuit 21a, and the clamp circuit 21a clamps the incoming color difference signal RY in response to the feedback, and outputs the color difference signal RY without DC offset. Further, the output signal of the limiter amplifier 22a is passed through the double wave rectifier 25.
a, where it is double-wave rectified to obtain a rectified signal.
また、同様にして端子２０ｂよりの色差信号Ｂ
−Ｙはクランプ回路２１ｂでクランプされた後リ
ミツタ増幅器２２ｂ、減衰器２３ｂ、アナログス
イツチ２４ｂに供給され、リミツタ増幅器２２ｂ
で色差信号Ｂ−Ｙをレベル制限及び増幅して得ら
れた信号はリミツタ増幅器２２ｂに帰還されると
共に両波整流器２５ｂに供給される。上記のクラ
ンプ回路２１ａ，２１ｂ、リミツタ増幅器２２
ａ，２２ｂ、両波整流回路２５ａ，２５ｂにより
レベル検出手段が構成されている。 Similarly, the color difference signal B from the terminal 20b is
-Y is clamped by the clamp circuit 21b and then supplied to the limiter amplifier 22b, the attenuator 23b, and the analog switch 24b.
The signal obtained by level-limiting and amplifying the color difference signal B-Y is fed back to the limiter amplifier 22b and also supplied to the double-wave rectifier 25b. The above clamp circuits 21a, 21b, limiter amplifier 22
A, 22b and double-wave rectifier circuits 25a, 25b constitute a level detection means.
両波整流器２５ａ，２５ｂ夫々の出力する整流
信号は選択回路２６に供給される。選択回路２６
はダイオード構成のオア回路の如きものであり、
上記２つの整流信号のうち電圧の高い整流信号を
選択して取り出す。選択回路２６で取り出された
整流信号は比較器２７ａ，２７ｂ夫々に供給され
る。比較器２７ａには端子２８ａより基準電位
Vref1が供給されており、上記整流信号は基準電
位Vref1と比較されて、整流信号が大なるとき例
えばＨレベル、小なるときＬレベルとなる制御信
号が生成されアナログスイツチ２４ａに供給され
る。また同様に比較器２７ｂは上記整流信号を端
子２８ｂよりの基準電圧Vref2と比較し、整流信
号が大なるときＨレベル、小なるときＬレベルの
制御信号を生成してアナログスイツチ２４ｂに供
給する。 The rectified signals output from each of the double-wave rectifiers 25a and 25b are supplied to a selection circuit 26. Selection circuit 26
is like an OR circuit with a diode configuration,
The rectified signal with the higher voltage is selected and extracted from the two rectified signals. The rectified signal taken out by the selection circuit 26 is supplied to comparators 27a and 27b, respectively. A reference potential is applied to the comparator 27a from the terminal 28a.
Vref 1 is supplied, and the rectified signal is compared with the reference potential Vref 1. When the rectified signal is large, a control signal is generated that is, for example, H level, and when it is small, it is L level, and is supplied to the analog switch 24a. . Similarly, the comparator 27b compares the rectified signal with the reference voltage Vref 2 from the terminal 28b, generates a control signal of H level when the rectified signal is large, and L level when it is small, and supplies it to the analog switch 24b. .
減衰器２３ａはクランプ回路２１ａよりの色差
信号Ｒ−Ｙを所定量だけ減衰させてアナログスイ
ツチ２４ａに供給する。アナログスイツチ２４ａ
は比較器２７ａからの制御信号がＨレベルのとき
クランプ回路２１ａよりの色差信号Ｒ−Ｙを取り
出し、制御信号がＬレベルのとき減衰器２３ａよ
りの減衰された色差信号Ｒ−Ｙを取り出して端子
２９ａより出力する。同様にしてアナログスイツ
チ２４ｂは比較器２７ｂからの制御信号がＨレベ
ルのときクランプ回路２１ｂよりの色差信号Ｂ−
Ｙを取り出し、制御信号がＬレベルのとき減衰器
２３ｂよりの減衰された色差信号Ｂ−Ｙを取り出
して端子２９ｂより出力する。上記の減衰器２３
ａ，２３ｂ及びアナログスイチ２４ａ，２４ｂに
よつて振幅制御手段が構成されている。 The attenuator 23a attenuates the color difference signal RY from the clamp circuit 21a by a predetermined amount and supplies it to the analog switch 24a. Analog switch 24a
When the control signal from the comparator 27a is at H level, the color difference signal R-Y from the clamp circuit 21a is taken out, and when the control signal is at L level, the attenuated color difference signal R-Y from the attenuator 23a is taken out and sent to the terminal. Output from 29a. Similarly, when the control signal from the comparator 27b is at H level, the analog switch 24b outputs the color difference signal B- from the clamp circuit 21b.
When the control signal is at L level, the attenuated color difference signal B-Y from the attenuator 23b is taken out and output from the terminal 29b. Attenuator 23 above
A, 23b and analog switches 24a, 24b constitute amplitude control means.
上記回路の色差信号の抑圧度特性を第２図Ａ〜
Ｄに示す。同図において一点鎖線及び二点鎖線で
示す信号抑圧閾値は比較器２７ａ，２７ｂ夫々の
基準電位Vref1，Vref2を入力色差信号の振幅に
換算したものと等価である。例えば第２図Ａの如
く、二点鎖線ａに示す色差信号Ｒ−Ｙの抑圧閾
値が一点鎖線ａに示す色差信号Ｂ−Ｙの抑圧閾
値より大として設定されている場合、一点鎖線
ａの範囲より大でかつ二点鎖線ａの範囲より小
である絶対値を持つ色差ベクトル３１は、そのＲ
−Ｙ成分３１ａが抑圧されてＢ−Ｙ成分３１ｂは
抑圧されない。このため抑圧により得られるＲ−
Ｙ成分３２ａと上記Ｂ−Ｙ成分３１ｂとの合成に
よつて色差ベクトル３２が生成される。 The suppression degree characteristics of the color difference signal of the above circuit are shown in Fig. 2A~
Shown in D. In the same figure, the signal suppression thresholds shown by the dashed-dotted line and the dashed-double-dotted line are equivalent to the reference potentials Vref 1 and Vref 2 of the comparators 27a and 27b, respectively, converted into the amplitude of the input color difference signal. For example, as shown in FIG. 2A, when the suppression threshold of the color difference signal RY shown by the dashed-dotted line a is set to be larger than the suppression threshold of the color difference signal B-Y shown by the dashed-dotted line a, the range of the dashed-dotted line a The color difference vector 31 whose absolute value is larger and smaller than the range of the two-dot chain line a is
-Y component 31a is suppressed and BY component 31b is not suppressed. Therefore, R- obtained by suppression
A color difference vector 32 is generated by combining the Y component 32a and the BY component 31b.
また、第２図Ｂの如く、二点鎖線ｂに示す色
差信号Ｒ−Ｙの抑圧閾値が二点鎖線ｂに示す色
差信号Ｂ−Ｙの抑圧閾値より小として設定されて
いる場合、一点鎖線ｂの範囲より小でかつ二点
鎖線ｂより大である絶対値を持つ色差ベクトル
３３は、そのＢ−Ｙ成分だけを抑圧されることに
より色差ベクトル３４とされる。 Further, as shown in FIG. 2B, when the suppression threshold of the color difference signal RY shown by the two-dot chain line b is set to be smaller than the suppression threshold of the color difference signal B-Y shown by the two-dot chain line b, the one-dot chain line b A color difference vector 33 having an absolute value smaller than the range of and larger than the two-dot chain line b is turned into a color difference vector 34 by suppressing only its BY component.
上記の色差信号Ｒ−Ｙ，Ｂ−Ｙ夫々の抑圧閾値
は比較器２７ａ，２７ｂ夫々における基準電位
Vref1，Vref2を可変することによつて変化し、
図中の原点を中心として拡大・縮小される。 The suppression thresholds of the color difference signals R-Y and B-Y are the reference potentials of the comparators 27a and 27b, respectively.
Changes by varying Vref 1 and Vref 2 ,
The image is enlarged or reduced around the origin in the diagram.
また、第２図Ｃに実線で示す色差信号Ｒ−Ｙ
又はＢ−Ｙの抑圧閾値のうちＲ−Ｙ軸に平行な部
分ａ，ｂ夫々はリミツタ増幅器２２ｂの増幅
度及び比較器２７ａ，２７ｂ夫々の基準電位
Vref1，Vref2夫々を可変することによつて図中
矢印に示す如くＢ−Ｙ軸方向に移動できる。ま
た、第２図Ｄに実線で示す色差信号Ｒ−Ｙ又は
Ｂ−Ｙの抑圧閾値のうちＢ−Ｙ軸に平行な部分
ａ，ｂ夫々はリミツタ増幅器２２ａの増幅度及
び比較器２７ａ，２７ｂ夫々の基準電位Vfef1，
Vref2夫々を可変することによつて図中矢印に示
す如くＲ−Ｙ軸方向に移動できる。従つてリミツ
タ増幅器２２ａ，２２ｂ夫々の増幅度を可変し
て、色差信号Ｒ−Ｙ，Ｂ−Ｙの抑圧閾値の縦横比
を可変することができる。 In addition, the color difference signal R-Y shown by the solid line in FIG.
Or, of the B-Y suppression threshold, the portions a and b parallel to the R-Y axis are the amplification degree of the limiter amplifier 22b and the reference potential of the comparators 27a and 27b, respectively.
By varying Vref 1 and Vref 2 , it is possible to move in the BY axis direction as shown by the arrow in the figure. In addition, the portions a and b parallel to the B-Y axis of the suppression threshold of the color difference signal R-Y or B-Y shown by the solid line in FIG. Reference potential Vfef 1 ,
By varying Vref 2 , it is possible to move in the RY axis direction as shown by the arrows in the figure. Therefore, by varying the degree of amplification of each of the limiter amplifiers 22a and 22b, it is possible to vary the aspect ratio of the suppression threshold of the color difference signals RY and BY.
このようにリミツタ増幅器２２ａ，２２ｂ夫々
の増幅度及び基準電位Vref1，Vref2夫々を可変
して色差信号Ｒ−Ｙ，Ｂ−Ｙ夫々を独立して抑圧
制御することが可能である。 In this way, it is possible to suppress and control the color difference signals RY and BY independently by varying the amplification degree of the limiter amplifiers 22a and 22b and the reference potentials Vref 1 and Vref 2 , respectively.
また、第２図Ａ，Ｂに示す如く、色差信号Ｒ−
Ｙ，Ｂ−Ｙ夫々の抑圧閾値を独立して設定するこ
とにより色差ベクトルの向きを可変することがで
き、例えばカラービデオカメラ等において色差信
号の位相がその振幅の影響を受け、小信号時に色
差信号の位相誤差を発生する場合、上記位相誤差
を補正することも可能である。また、色差ベクト
ルの向きを変化させる必要のない場合には色差信
号Ｒ−Ｙ，Ｂ−Ｙ夫々の抑圧閾値を同一に設定す
る。 Furthermore, as shown in FIGS. 2A and 2B, the color difference signal R-
By setting the Y and B-Y suppression thresholds independently, the direction of the color difference vector can be varied. For example, in a color video camera, the phase of the color difference signal is affected by its amplitude, and the color difference is suppressed when the signal is small. When a phase error of the signal is generated, it is also possible to correct the phase error. Furthermore, when there is no need to change the direction of the color difference vector, the suppression thresholds for the color difference signals RY and BY are set to be the same.
更に、色差信号Ｒ−Ｙ，Ｂ−Ｙ夫々はクランプ
回路２１ａ，２１ｂ夫々でクランプされた後、抑
圧されるため、従来の如く、直流オフセツトによ
る抑圧誤差の発生を防止することができる。 Furthermore, since the color difference signals R-Y and B-Y are each clamped by the clamp circuits 21a and 21b and then suppressed, it is possible to prevent the generation of suppression errors due to DC offset, as in the prior art.
なお、本発明回路はカラービデオカメラに限ら
ず、色差信号の処理を行なう他のどのような装置
にも適用できる。また、色差信号Ｒ−Ｙ，Ｂ−Ｙ
の他に色差信号Ｇ−Ｙに対しても同様にして雑音
低減を行なつても良く、上記実施例に限定されな
い。 Note that the circuit of the present invention is applicable not only to color video cameras but also to any other devices that process color difference signals. In addition, the color difference signals R-Y, B-Y
In addition, noise reduction may be performed on the color difference signal GY in a similar manner, and the present invention is not limited to the above embodiment.
発明の効果
上述の如く、本発明になる色差信号の雑音低減
回路は、入来する複数の色差信号夫々のレベル検
出を行なうレベル検出手段と、複数の色差信号
夫々のレベル検出信号のうち最大レベルのレベル
検出信号を選択する選択手段と、複数の色差信号
夫々に対応した複数の基準電位を有し複数の基準
電位夫々と選択されたレベル検出信号とを比較し
て複数の色差信号夫々に対応した制御信号を生成
する比較手段と、複数の制御信号に応じて夫々に
対応する色差信号の振幅抑圧を行なう振幅制御手
段とより構成したため、複数の色差信号夫々に独
立して最適な雑音低減を行ない得、また色差信号
夫々に直流オフセツトが発生せず抑圧誤差の発生
を防止でき、更に小信号の色差信号の位相誤差を
も補正することができる等の特長を有している。Effects of the Invention As described above, the color difference signal noise reduction circuit according to the present invention includes a level detecting means for detecting the level of each of a plurality of incoming color difference signals, and a level detection means for detecting the level of each of the plurality of color difference signals, and detecting the maximum level of the level detection signal of each of the plurality of color difference signals. a selection means for selecting a level detection signal, and a selection means having a plurality of reference potentials corresponding to each of the plurality of color difference signals, and comparing each of the plurality of reference potentials and the selected level detection signal to correspond to each of the plurality of color difference signals. The structure is comprised of a comparison means for generating a control signal, and an amplitude control means for suppressing the amplitude of the corresponding color difference signals according to a plurality of control signals, so that optimum noise reduction can be performed independently for each of the plurality of color difference signals. Furthermore, it has the advantage that no direct current offset occurs in each of the color difference signals, thereby preventing the occurrence of suppression errors, and further, that phase errors of small color difference signals can also be corrected.
第１図は本発明回路の一実施例のブロツク系統
図、第２図は第１図示の回路の特性図、第３図は
従来回路の一例のブロツク系統図、第４図は第３
図示の回路の特性図である。
２０ａ，２０ｂ，２８ａ，２８ｂ，２９ａ，２
９ｂ……端子、２１ａ，２１ｂ……クランプ回
路、２２ａ，２２ｂ……リミツタ増幅器、２３
ａ，２３ｂ……減衰器、２４ａ，２４ｂ……アナ
ログスイツチ、２５ａ，２５ｂ……両波整流器、
２６……選択回路、２７ａ，２７ｂ……比較器。
FIG. 1 is a block system diagram of an embodiment of the circuit of the present invention, FIG. 2 is a characteristic diagram of the circuit shown in FIG. 1, FIG. 3 is a block system diagram of an example of a conventional circuit, and FIG.
FIG. 3 is a characteristic diagram of the illustrated circuit. 20a, 20b, 28a, 28b, 29a, 2
9b...terminal, 21a, 21b...clamp circuit, 22a, 22b...limiter amplifier, 23
a, 23b...attenuator, 24a, 24b...analog switch, 25a, 25b...double wave rectifier,
26... Selection circuit, 27a, 27b... Comparator.
Claims (1)
行なうレベル検出手段と、該複数の色差信号夫々
のレベル検出信号のうち最大レベルのレベル検出
信号を選択する選択手段と、該複数の色差信号
夫々に対応した複数の基準電位を有し該複数の基
準電位夫々と選択されたレベル検出信号とを比較
して該複数の色差信号夫々に対応した制御信号を
生成する比較手段と、該複数の制御信号に応じて
夫々に対応する色差信号の振幅抑圧を行なう振幅
制御手段とより構成したことを特徴とする色差信
号の雑音低減回路。 ２ 該レベル検出手段は、該複数の色差信号夫々
をクランプしてレベル制限増幅を行なつた後両波
整流する構成としたことを特徴とする特許請求の
範囲第１項記載の色差信号の雑音低減回路。 ３ 該振幅制御手段は、該複数の色差信号夫々を
減衰した信号と該複数の色差信号夫々とを該複数
の制御信号夫々に応じて切換え出力する構成とし
たことを特徴とする特許請求の範囲第１項記載の
色差信号の雑音低減回路。[Scope of Claims] 1. Level detection means for detecting the level of each of a plurality of incoming color difference signals, and selection means for selecting a level detection signal with a maximum level among the level detection signals of each of the plurality of color difference signals; Comparing means has a plurality of reference potentials corresponding to each of the plurality of color difference signals, and compares each of the plurality of reference potentials with a selected level detection signal to generate a control signal corresponding to each of the plurality of color difference signals. and amplitude control means for suppressing the amplitude of the corresponding color difference signals in accordance with the plurality of control signals. 2. The noise in the color difference signal as set forth in claim 1, wherein the level detection means is configured to clamp each of the plurality of color difference signals, perform level limiting amplification, and then perform double wave rectification. reduction circuit. 3. Claims characterized in that the amplitude control means is configured to switch and output a signal obtained by attenuating each of the plurality of color difference signals and each of the plurality of color difference signals in accordance with each of the plurality of control signals. 2. The color difference signal noise reduction circuit according to item 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13264884A JPS6112192A (en) | 1984-06-27 | 1984-06-27 | Circuit for reducing noises of color difference signal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13264884A JPS6112192A (en) | 1984-06-27 | 1984-06-27 | Circuit for reducing noises of color difference signal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6112192A JPS6112192A (en) | 1986-01-20 |
| JPH0320195B2 true JPH0320195B2 (en) | 1991-03-18 |
Family
ID=15086232
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13264884A Granted JPS6112192A (en) | 1984-06-27 | 1984-06-27 | Circuit for reducing noises of color difference signal |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6112192A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS599486A (en) * | 1982-07-09 | 1984-01-18 | 太田 正之 | Method of drying veneer |
-
1984
- 1984-06-27 JP JP13264884A patent/JPS6112192A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6112192A (en) | 1986-01-20 |
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