JP2532968B2 - Color video camera - Google Patents
Color video cameraInfo
- Publication number
- JP2532968B2 JP2532968B2 JP2113127A JP11312790A JP2532968B2 JP 2532968 B2 JP2532968 B2 JP 2532968B2 JP 2113127 A JP2113127 A JP 2113127A JP 11312790 A JP11312790 A JP 11312790A JP 2532968 B2 JP2532968 B2 JP 2532968B2
- Authority
- JP
- Japan
- Prior art keywords
- effective area
- color
- gain
- screen
- white balance
- 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 - Fee Related
Links
Landscapes
- Processing Of Color Television Signals (AREA)
Description
【発明の詳細な説明】 （イ）産業上の利用分野 本発明は，撮像素子から得られる撮像映像信号を基
に、白バランスの制御を行うカラービデオカメラの自動
白バランス調整装置に関する。The present invention relates to an automatic white balance adjusting device for a color video camera that controls white balance based on an image pickup video signal obtained from an image pickup device.
（ロ）従来の技術 カラービデオカメラに於いては、光源による光の波長
分布の違いを補正するために、白バランスの制御を行う
必要がある。(B) Conventional Technology In a color video camera, it is necessary to control white balance in order to correct the difference in the wavelength distribution of light depending on the light source.
この制御は、赤（以下Ｒ）、青（以下Ｂ）、緑（以下
Ｇ）の三原色信号の比が1:1:1となるように、各色信号
の利得を調節することで行われる。一般には例えば特開
昭62−35792号公報（H04N9/73）に示される様に、画面
の色差信号Ｒ−Ｙ、Ｂ−Ｙの積分値が零になるように利
得を調節する方式が用いられている。This control is performed by adjusting the gain of each color signal so that the ratio of the three primary color signals of red (hereinafter R), blue (hereinafter B), and green (hereinafter G) is 1: 1: 1. Generally, for example, as shown in JP-A-62-35792 (H04N9 / 73), a method of adjusting the gain so that the integrated value of the color difference signals RY and BY of the screen becomes zero is used. ing.
第２図は、この方式を用いた白バランス調整回路のブ
ロック図である。FIG. 2 is a block diagram of a white balance adjusting circuit using this method.
レンズ（１）を通過した光は、撮像素子（CCD）
（２）で光電変換された後、色分離回路（３）で、Ｒ、
Ｇ、Ｂの３原色信号として取り出される。Ｒ増幅回路
（４）、Ｂ増幅回路（５）を経て、カメラプロセス及び
マトリクス回路（６）に入力され、輝度信号Ｙ、赤及び
青それぞれの色差信号Ｒ−Ｙ、Ｂ−Ｙが作られて、ビデ
オ回路へ送られる。The light that has passed through the lens (1) is the image sensor (CCD).
After photoelectric conversion in (2), R,
It is taken out as three primary color signals of G and B. It is input to the camera process and matrix circuit (6) through the R amplifier circuit (4) and the B amplifier circuit (5), and the luminance signal Y and the color difference signals RY and BY of red and blue are generated. , Sent to the video circuit.
同時に、二つの色差信号は、それぞれ積分回路（17）
（18）で、所定の時間だけ積分され、その結果がいずれ
も零になるように利得制御回路（13）、（14）がＲ、Ｂ
各々の増幅回路（４）、（５）の利得を調節する利得調
整信号を発する。At the same time, the two color difference signals are respectively integrated by an integrating circuit (17).
In (18), the gain control circuits (13) and (14) are integrated by R and B so that they are integrated for a predetermined time and the results are both zero.
A gain adjustment signal for adjusting the gain of each amplifier circuit (4), (5) is issued.
尚、前述の各色差信号の基準レベル、即ち、零レベル
は、画面全体が無彩色の被写体を撮影した時に得られる
信号レベルに予め設定されている。The reference level of each of the color difference signals, that is, the zero level, is set in advance to a signal level obtained when a subject whose entire screen is achromatic is photographed.
（ハ）発明が解決しようとする課題 前述の方式はビデオカメラにより撮影される画面の様
々な色分布に対して、積分回路（17）（18）の時定数を
長くする等の工夫を施して、これらの色分布を平均化す
れば、色分布を構成する各色成分が打ち消し合い、略白
い画面状態に近似できることを前提としている。(C) Problems to be Solved by the Invention The above-mentioned method has been devised such that the time constants of the integrating circuits (17) and (18) are lengthened for various color distributions of the screen shot by the video camera. It is premised that if these color distributions are averaged, the color components that make up the color distributions cancel each other out and that a substantially white screen state can be approximated.
ところが、レンズの画角が狭いか、もしくは被写体と
の距離が近い場合には、画面の中に入る実効的な面積が
小さくなり、画面内の色の積分結果に偏りを生じやす
い。However, when the angle of view of the lens is narrow or the distance to the subject is short, the effective area of entering the screen becomes small, and the result of color integration within the screen tends to be biased.
例えば、赤いセータを着た人物をクローズアップする
場合等では、画面全体の色分布を平均化しても白い画面
状態とはならず白バランスがくずれることになり、この
様な被写体に対して前述の如き白バランス調整を施せ
ば、偏った色を打ち消す方向に利得が変化して白バラン
スがその補色側にずれて、適正な色の再現が行えなくな
るという欠点を有している。For example, in the case of taking a close-up of a person wearing a red sweater, even if the color distribution of the entire screen is averaged, the white screen is not obtained and the white balance is lost. If such white balance adjustment is performed, the gain changes in the direction of canceling the biased color, the white balance shifts to the complementary color side, and proper color reproduction cannot be performed.
（ニ）課題を解決するための手段 本発明は、撮像映像信号中の色情報信号を基に白バラ
ンス調整を行うものであり、撮影レンズの画角及び被写
体との距離を検出し、これらの値から画面内の被写体の
実効面積を算出して、その結果に基づいて白バランス調
整の調整速度を多段階に変化させるか、もしくは現在の
色情報信号での白バランス調整を中止することを特徴と
する。(D) Means for Solving the Problems The present invention is to perform white balance adjustment based on a color information signal in an imaged video signal, and detects the angle of view of the photographing lens and the distance to the subject, The effective area of the subject on the screen is calculated from the values, and the adjustment speed of white balance adjustment is changed in multiple stages based on the result, or white balance adjustment with the current color information signal is stopped. And
（ホ）作用 本発明は、上述の如く構成したので、画角が狭い、或
いは被写体の距離が近いために画面内に十分に多くの被
写体を含まないために、画面内の色に偏りを生じ、白バ
ランスがその補色側へずれることを軽減する。(E) Action Since the present invention is configured as described above, a sufficient angle of view is not included in the screen because the angle of view is narrow or the distance between the objects is short. , To reduce the shift of white balance to the complementary color side.
（ヘ）実施例 以下、図面に従い本発明の一実施例について説明す
る。(F) Embodiment One embodiment of the present invention will be described below with reference to the drawings.
第１図は本実施例による自動白バランス調整回路の回
路ブロック図である。尚、図中、従来例と同一の部分に
ついては説明を省略する。FIG. 1 is a circuit block diagram of an automatic white balance adjusting circuit according to this embodiment. Incidentally, in the figure, the description of the same parts as those of the conventional example will be omitted.
（20）は一般のビデオカメラに用いられている周知の
ズーム機構であり、このズーム機構を構成するズームレ
ンズを変位させることにより、カメラ全体のレンズ系の
焦点距離を変化させて広角〜望遠のズーム領域から所望
の画角を選択することが可能となる。Reference numeral (20) is a well-known zoom mechanism used in general video cameras. By displacing the zoom lens that constitutes this zoom mechanism, the focal length of the lens system of the entire camera is changed to change the wide-angle to telephoto range. It is possible to select a desired angle of view from the zoom area.
画角検出回路（21）は、ズームレンズの位置を検出し
てその時点でのズーム領域中での位置を検知して、第４
図の関係から画面の横方向の画角（RW）（単位はラジア
ン）と縦方向の画角（RL）を算出する。ところで、第４
図では当然のことであるが、ズーム位置が広角側にある
程に画角（RW）（RL）は大きくなる。The angle-of-view detection circuit (21) detects the position of the zoom lens, detects the position in the zoom area at that time, and detects the fourth position.
Lateral angle (R W) from the relationship window in FIG. (Radians) calculates the vertical angle of view (R L). By the way, the fourth
It will be appreciated that in the figure, the angle of view to the extent that the zoom position is on the wide angle side (R W) (R L) increases.
（22）は被写体までの距離を赤外線等を用いて測定
し、この被写体距離に応じてレンズ（１）を光軸方向に
進退させて合焦状態とする周知のフォーカス機構であ
り、このフォーカス機構にて得られた被写体距離（Ｌ）
の情報は、後段の実効面積算出回路（23）に入力され
る。Reference numeral (22) is a well-known focus mechanism that measures the distance to a subject using infrared rays and the like, and moves the lens (1) forward and backward in the optical axis direction according to the subject distance to bring the lens into focus. Subject distance (L) obtained in
Information is input to the effective area calculation circuit (23) at the subsequent stage.
実効面積算出回路（23）では、画角検出回路（21）か
らの画角（RW）（RL）及びフォーカス機構（22）からの
被写体距離（Ｌ）に基づいて画面に含まれる全被写体
（主要被写体と背景を含む画面全体に映出されている全
てのもの）の実効的な量（面積）が算出される。具体的
には、実効面積（Ｓ）は次式にて求まる。In the effective area calculating circuit (23), the angle from the angle detector (21) (R W) (R L) and total subject contained in the screen on the basis of the object distance (L) from the focus mechanism (22) An effective amount (area) of (everything displayed on the entire screen including the main subject and the background) is calculated. Specifically, the effective area (S) is calculated by the following formula.
Ｓ＝（RW×Ｌ）×（RL×Ｌ） この式中、（RW×Ｌ）は全被写体の横方向の実効長
さ、（RL×Ｌ）は全被写体の縦方向の実効長さを示して
いる。S = in (R W × L) × ( R L × L) This formula, (R W × L) is horizontal effective length of the entire object, (R L × L) is vertical for all subject an effective Shows the length.
こうして得られた実効面積（Ｓ）は、第２図の積分回
路（17）（18）と同様に各色差信号を積分する積分回路
（117）（118）に送られて、夫々の積分の時定数を変化
させる。即ち、積分回路（117）（118）は実効面積
（Ｓ）が小さくなるにつれてその時定数が長くなり、実
効面積（Ｓ）が所定の閾値を下回る時には、時定数が無
限代となる様に構成されている。尚、所定の閾値は実効
面積が著しく小さいために、画面評価では適正な白バラ
ンス調整が困難と認められる値であり、予め実験データ
にて設定されている。The effective area (S) thus obtained is sent to the integrating circuits (117) (118) for integrating each color difference signal as in the integrating circuits (17) (18) in FIG. Change the constant. That is, the integration circuits (117) and (118) are configured such that their time constant becomes longer as the effective area (S) becomes smaller, and the time constant becomes infinite when the effective area (S) falls below a predetermined threshold value. ing. It should be noted that the predetermined threshold is a value at which it is recognized that proper white balance adjustment is difficult in screen evaluation because the effective area is extremely small, and is set in advance by experimental data.
この結果、実効面積が小さく、色差信号の積分値の信
頼性が低い場合には、積分時間を長くとることで、より
多くの情報に基づいて白バランスが適正か否かの判断を
行うように制御され、結果的に画面評価による利得調整
のレスポンスを鈍くできることになる。また、実効面積
（Ｓ）が所定の閾値を下回れば、時定数は無限大となっ
て積分結果に変化が得られなくなり、利得制御回路（1
3）（14）での利得制御は、前回の画面評価の結果に基
づく状態に保持される。As a result, when the effective area is small and the reliability of the integrated value of the color difference signal is low, the integration time is set to be long so that the white balance can be determined based on more information. As a result, the response of gain adjustment by screen evaluation can be slowed down as a result. If the effective area (S) is less than the predetermined threshold value, the time constant becomes infinite and the integration result cannot be changed, and the gain control circuit (1
3) The gain control in (14) is held in a state based on the result of the previous screen evaluation.
また、第３図に示す様に、実効面積算出回路（23）出
力を積分回路（17）（18）に入力してその時定数を制御
する代りに、第２図の利得制御回路（13）（14）と同様
にＲ及びＢ増幅回路（４）（５）の利得を制御する利得
制御回路（113）（114）に送り、Ｒ及びＢの各々の増幅
利得率を変化させる時の時定数を規制することも可能で
ある。即ち、実効面積（Ｓ）が小さくなるにつれて利得
の変化を遅くし、所定の閾値を下回る時には変化を停止
させる様にする。例えば、利得制御回路（113）（114）
での制御により、基準の実効面積（So）での単位時間当
りの利得の変化量を（g0）とすると、算出回路（23）に
て算出された実効面積（Ｓ）での単位時間当りの利得の
変化量（ｇ）がｇ＝g0×（S/So）となる様に設定する。
これにより、積分結果に基づいて決定される現利得に対
する補正量だけ利得を変化させるのに要する時間は、実
効面積が小さくなるにつれて大きくなり、結果的に利得
調整のレスポンスを鈍くできることのなる。また、実効
面積（Ｓ）が所定の閾値を下回る時には、画面評価に基
づく白バランス調整を行うには十分な面積がないとし
て、ｇ＝０として利得の変化を停止させることになる。Further, as shown in FIG. 3, instead of inputting the output of the effective area calculating circuit (23) to the integrating circuits (17) and (18) to control the time constant thereof, the gain control circuit (13) ( Similarly to 14), send to the gain control circuit (113) (114) that controls the gain of the R and B amplification circuits (4) and (5), and set the time constant when changing the amplification gain ratio of each of R and B. It is also possible to regulate. That is, the change in gain is delayed as the effective area (S) becomes smaller, and the change is stopped when the effective area (S) falls below a predetermined threshold value. For example, gain control circuits (113) (114)
When the amount of change in gain per unit time at the reference effective area (S o ) is set to (g 0 ) by the control by, the unit time at the effective area (S) calculated by the calculation circuit (23) The change amount (g) of the gain per hit is set so that g = g 0 × (S / S o ).
As a result, the time required to change the gain by the correction amount with respect to the current gain determined based on the integration result increases as the effective area decreases, and as a result, the gain adjustment response can be slowed down. Further, when the effective area (S) is smaller than a predetermined threshold value, it is determined that there is not enough area for white balance adjustment based on the screen evaluation, and the gain change is stopped by setting g = 0.
こうして前述の実施例と同様の効果を期待することが
できる。In this way, the same effect as that of the above-described embodiment can be expected.
以上の各回路の動作は、マイクロコンピュータを用い
てソフトウェア的に処理可能であることは言うまでもな
い。It goes without saying that the operation of each circuit described above can be processed by software using a microcomputer.
（ト）発明の効果 上述の如く本発明によれば、画角が狭く、また被写体
の距離が近いために画面内に十分に多くの被写体を含ま
ないと判断される場合には、色情報信号を用いた画面評
価に時間を多くかけて、より多くの色情報信号にて画面
評価が為され、特に実効面積が著しく小さい場合には、
この実効面積内に多くの被写体を含まない傾向が著し
く、白バランスの評価対象として好ましくないので、画
面評価に基づく白バランス調整が禁止され、画面内の色
に偏りに基づき、白バランスがその補色側へずれる惧れ
が軽減される。(G) Effect of the Invention As described above, according to the present invention, when it is determined that a sufficient number of subjects are not included in the screen because the angle of view is narrow and the subject distance is short, the color information signal It takes a lot of time to evaluate the screen using, and the screen is evaluated with more color information signals, especially when the effective area is extremely small.
Since there is a marked tendency that many subjects are not included in this effective area and it is not suitable for white balance evaluation, white balance adjustment based on screen evaluation is prohibited, and the white balance is a complementary color based on the color bias in the screen. The fear of shifting to the side is reduced.
第１図は本発明の一実施例の回路ブロック図、第３図は
他の実施例の回路ブロック図、第４図はズーム位置と画
角の関係を示す図、第２図は従来例を示す図である。 （23）…実行面積算出回路。FIG. 1 is a circuit block diagram of an embodiment of the present invention, FIG. 3 is a circuit block diagram of another embodiment, FIG. 4 is a diagram showing a relationship between a zoom position and an angle of view, and FIG. 2 is a conventional example. FIG. (23) ... Execution area calculation circuit.
Claims (1)
信号の利得制御を行うカラービデオカメラにおいて、 レンズの画角及び被写体までの距離を得て、撮像画面内
の実効面積を求める実効面積検出部を設け、該実効面積
に応じて、該利得制御の時定数を変え、該実効面積が所
定の値を下回るとき前記利得制御を停止することを特徴
とするカラービデオカメラ。1. A color video camera that controls the gain of each color signal based on a color information signal in the picked-up video signal, obtains an angle of view of a lens and a distance to a subject, and obtains an effective area in an image pickup screen. A color video camera comprising an effective area detection unit, changing a time constant of the gain control according to the effective area, and stopping the gain control when the effective area falls below a predetermined value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2113127A JP2532968B2 (en) | 1990-04-27 | 1990-04-27 | Color video camera |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2113127A JP2532968B2 (en) | 1990-04-27 | 1990-04-27 | Color video camera |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0410887A JPH0410887A (en) | 1992-01-16 |
| JP2532968B2 true JP2532968B2 (en) | 1996-09-11 |
Family
ID=14604224
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2113127A Expired - Fee Related JP2532968B2 (en) | 1990-04-27 | 1990-04-27 | Color video camera |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2532968B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7551209B2 (en) | 2002-02-27 | 2009-06-23 | Hitachi, Ltd. | Imaging apparatus and method for controlling white balance |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4811494B2 (en) * | 2009-04-03 | 2011-11-09 | 株式会社日立製作所 | Imaging device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03148988A (en) * | 1989-11-02 | 1991-06-25 | Minolta Camera Co Ltd | White balance adjusting device |
-
1990
- 1990-04-27 JP JP2113127A patent/JP2532968B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7551209B2 (en) | 2002-02-27 | 2009-06-23 | Hitachi, Ltd. | Imaging apparatus and method for controlling white balance |
| US8130284B2 (en) | 2002-02-27 | 2012-03-06 | Hitachi, Ltd. | Imaging apparatus and method for controlling white balance |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0410887A (en) | 1992-01-16 |
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