JPH0616134B2 - Automatic focus control method for camera - Google Patents
Automatic focus control method for cameraInfo
- Publication number
- JPH0616134B2 JPH0616134B2 JP59244302A JP24430284A JPH0616134B2 JP H0616134 B2 JPH0616134 B2 JP H0616134B2 JP 59244302 A JP59244302 A JP 59244302A JP 24430284 A JP24430284 A JP 24430284A JP H0616134 B2 JPH0616134 B2 JP H0616134B2
- Authority
- JP
- Japan
- Prior art keywords
- image
- camera
- screen
- difference
- automatic focus
- 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 - Lifetime
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/28—Systems for automatic generation of focusing signals
- G02B7/36—Systems for automatic generation of focusing signals using image sharpness techniques, e.g. image processing techniques for generating autofocus signals
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Vision & Pattern Recognition (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Automatic Focus Adjustment (AREA)
- Focusing (AREA)
Description
【発明の詳細な説明】 (産業上の利用分野) 本発明はカメラの自動焦点調整方法,殊に結像画面の鮮
明度検出方法に関する。The present invention relates to an automatic focus adjustment method for a camera, and more particularly to a sharpness detection method for an imaged screen.
(従来技術) カメラの焦点調整は,フアインダーから結像面をモニタ
しつつ或は,テレビカメラの場合はテレビ受像機をモニ
タしながら人偽的に行うのが一般的であるが,これを自
動的に調整する方法も各種提案されている。(Prior Art) Generally, the focus adjustment of a camera is artificially performed while observing an image forming surface from a finder or in the case of a TV camera while observing a TV receiver. Various methods have been proposed for adjusting manually.
従来,自動焦点調整方法としては,超音波による測距装
置を用いこれとレンズ移動機構と組合せたもの,或はカ
メラ前面の所定距離隔てた2点の夫々の結像が一致する
如くレンズを移動せしめた所謂光学的測距儀を用いたも
の等がある。Conventionally, as an automatic focus adjustment method, a distance measuring device using an ultrasonic wave is used in combination with a lens moving mechanism, or the lens is moved so that two images separated by a predetermined distance on the front surface of the camera coincide with each other. There is a device using a so-called optical rangefinder.
しかし,前者の超音波を用いる方法は,比較的簡単に距
離測定が可能であるものの結像画面とは無関係に被写体
とカメラとの距離を計測するものであるから,カメラが
ズーム機構を有して結像の倍率が変化する場合の測距精
度に難点がある,又後者の三角測距方法ではこれを自動
焦点調整に適用せんとすれば,2つの結像の一致点を判
別する手段が別途必要となり複雑とならざるを得ない。However, in the former method using ultrasonic waves, although the distance can be measured relatively easily, since the distance between the subject and the camera is measured independently of the image formation screen, the camera has a zoom mechanism. Therefore, there is a problem in the accuracy of distance measurement when the magnification of image formation changes, and if the latter method of triangulation is not applied to automatic focus adjustment, there is a means to determine the coincident point of two image formations. It is necessary separately and complicated.
特に遠隔地に設置したテレビカメラの自動焦点調整に適
用し種々カメラの方向或は被写***置が変化する場合,
更にはこれら映像信号を通信回線を介して所要の場所に
伝送する場合のこれらテレビカメラの自動焦点調整方法
としては上記従来の方法はいずれも最適なものとは云い
難い。Especially when it is applied to the automatic focus adjustment of a TV camera installed in a remote place and the direction of various cameras or the position of the subject changes,
Furthermore, none of the above-mentioned conventional methods is optimal as an automatic focus adjustment method for these TV cameras when these video signals are transmitted to a required place via a communication line.
(発明の目的) 本発明は,以上説明したような従来のカメラ自動焦点調
整方法の欠点を補い,特にテレビカメラの自動焦点調整
方法に適した方法を提供することを目的とする。(Object of the Invention) An object of the present invention is to provide a method suitable for an automatic focus adjusting method of a television camera, in which the drawbacks of the conventional camera automatic focus adjusting method described above are compensated.
(発明の構成) 本発明はこの目的達成のため以下の如き構成をとる。(Structure of the Invention) The present invention has the following structures to achieve this object.
即ち,テレビカメラの映像信号はブラウン管に表示する
関係から電気信号,所謂ビデオ信号に変換される。That is, the video signal of the television camera is converted into an electric signal, a so-called video signal, because it is displayed on the cathode ray tube.
本発明はこのように電気信号に変換された映像信号から
結像の鮮明度を検出するものであって,該結像画面を所
要の画素に分割すると共に,左右又は上下に隣接する前
記画素の明暗或は色相等を比較しその差分を抽出し,該
差分の総和が最大になる如くカメラの焦点調整機構を制
御するよう構成する。The present invention detects the sharpness of image formation from the video signal thus converted into an electric signal, and divides the image formation screen into required pixels, and the pixels of the adjacent pixels vertically or vertically. The light-darkness or hue is compared, the difference is extracted, and the focus adjustment mechanism of the camera is controlled so that the total sum of the differences is maximized.
(実施例) 以下本発明を図示した実施例に基づいて詳細に説明す
る。(Example) Hereinafter, the present invention will be described in detail based on illustrated examples.
第1図(a)(b)及び(c)は夫々本発明の原理を説明するた
めの図である。FIGS. 1 (a), (b) and (c) are diagrams for explaining the principle of the present invention.
先づ,同図(a)は適正なピントによってブラウン管に表
示された円形画像を示す図である。First, FIG. 1 (a) is a diagram showing a circular image displayed on a cathode ray tube with proper focus.
今,この画面を16×16の画素に分割し,夫々の画素
の明暗を例えば0から3までの4段階に区分して表示す
ると,同図(a)の如くなる。Now, when this screen is divided into 16 × 16 pixels and the brightness of each pixel is divided into, for example, four levels from 0 to 3 and displayed, it becomes as shown in FIG.
即ち,該結像円の内部に位置する角画素濃度は3,外部
は0であるとする。この状態から被写体が移動する等し
てピントがずれると,同図(c)に示す如く画面上の結像
がボケ,その結果該結像全体が若干膨張すると同時に結
像の輪郭像がはっきりせずその濃度変化が緩慢となって
輪郭部に中間濃度部分を生ずる。That is, it is assumed that the density of the corner pixels located inside the imaging circle is 3 and the density of the outside is 0. When the subject moves out of focus from this state, the image on the screen becomes blurred as shown in Fig. 6 (c), and as a result, the entire image is slightly expanded and the contour image of the image becomes clear. At the same time, the change in the density becomes slow and an intermediate density portion is generated in the contour portion.
今,このような2つの状態に於ける各画面中央矢印部の
水平方向画素列Mnを抽出すると夫々第1図(d)及び(e)
となる。Now, when the horizontal pixel row Mn of the central arrow portion of each screen in such two states is extracted, it is respectively shown in FIGS.
Becomes
次にこの画素列Mnの隣接するものの濃度差△Mを求め
ると夫々同図(f)及び(g)に示す如くなり,更にこれらの
差,即ち2次差分△Jnを求めると夫々(h)及び(i)に示
す如くなる。Next, when the density difference ΔM of the adjacent ones of the pixel rows Mn is obtained, it becomes as shown in FIGS. 6 (f) and (g), respectively, and further, the difference, that is, the secondary difference ΔJn is obtained (h). And as shown in (i).
このようにして求めた各画素列の2次差分の和Kn=|
△Jn|を比較するとこの図から明らかな如く,ピント
の合った結像図(b)ではKn=12又ピントのずれた結
像(c)ではKn=4となってピントが合った結像の2次
差分和Knが大きくなることがわかる。The sum of the quadratic differences Kn = |
By comparing ΔJn |, it is clear from this figure that Kn = 12 in the in-focus image (b) or Kn = 4 in the out-of-focus image (c). It can be seen that the second-order difference sum Kn of
即ち,本発明はこのように結像輪郭部の濃淡或は色相の
差分がピントのずれに応じて変化し,適切なピントにて
これが最大となる現象を利用して自動焦点調整を行うも
のである。That is, according to the present invention, the automatic focus adjustment is performed by utilizing such a phenomenon that the difference in shade or hue of the image-forming contour portion changes in accordance with the focus shift, and this becomes maximum at an appropriate focus. is there.
以下,その具体的な方法を実施例によって説明する。The specific method will be described below with reference to examples.
第2図は本発明を適用したスロースキャンテレビ(SS
TV)用カメラの自動焦点調整装置の一実施例を示すブ
ロック図である。FIG. 2 shows a slow scan television (SS
It is a block diagram which shows one Example of the automatic focus adjustment device of the camera for TV.
同図に於いて,1はテレビカメラであって,これに付属
する作像管2は結像を電気信号に変換してビデオ信号A
を出力し,図示を省略した受像装置に伝送すると共に,
その一部をA/D変換器3に入力する。In the figure, reference numeral 1 is a television camera, and a picture tube 2 attached to the television camera 2 converts a formed image into an electric signal to produce a video signal A.
Is output and transmitted to an image receiving device (not shown),
A part of it is input to the A / D converter 3.
更にA/D変換器でビデオ信号をデジタル信号に変換し
たのちこれを上述の如く画面を所要数の画素に区分し夫
々の画素の濃淡を数値化して画像メモリ4に記憶すると
共に次段の制御部5に於いてこれら記憶した画素の濃淡
差分の全画面又は画面の一部に於ける和S=ΣKnを検
出しつつモータ駆動部6を介して前記テレビカメラ1に
付加したレンズ移動用モータ7を制御し,その焦点距離
を変化せしめるよう構成する。Further, after converting the video signal into a digital signal by the A / D converter, the screen is divided into a required number of pixels as described above, and the shading of each pixel is digitized and stored in the image memory 4 and the control of the next stage is performed. The lens moving motor 7 added to the television camera 1 through the motor driving unit 6 while detecting the sum S = ΣKn of the stored grayscale difference of the pixels in the entire screen or a part of the screen in the unit 5. Is controlled, and the focal length is changed.
このように構成したSSTVの自動焦点調整装置の制御
アルゴリズムの一例を第3図に示したフローチャートを
用いて説明する。An example of the control algorithm of the SSTV automatic focus adjustment device thus configured will be described with reference to the flow chart shown in FIG.
同図に於いて,先づステップ1に於いてレンズの焦点距
離Lを初期LOに設定しステップ2に於いてこのときの
画像の画素濃淡差分和S1を前記制御部5に於いて検出
すると共にステップ3でこの差分を画像メモリー4に記
憶せしめる。In the figure, first, in step 1, the focal length L of the lens is set to the initial L O, and in step 2, the pixel density difference sum S 1 of the image at this time is detected by the control section 5. At the same time, in step 3, this difference is stored in the image memory 4.
次にステップ4ではモータ7を駆動してカメラの焦点距
離Lを微か△L大きくしてL=LO+△Lとすると共
に,ステップ5で再度画素濃淡差分和S1を検出して,
これと前記ステップ3に於いて記憶したS2との比較を
行いその差△S=S1−S2を求める。Then by driving the motor 7 in step 4 with a focal length L of the camera faintly △ L by increasing the L = L O + △ L, and detects the pixel shading difference sum S 1 again in Step 5,
This is compared with S 2 stored in step 3 to obtain the difference ΔS = S 1 −S 2 .
このとき,前記△Sが正であれば,焦点距離を△L大き
くしたことによって,より画像が鮮明になったことにな
り,更に少し長くする事によりもっと画像が鮮明になる
可能性があるし,その逆に△Sが負であれば,レンズ焦
点距離結像を若干長くしたことにより,画像がボケたこ
とになるから焦点距離をもっと短くすべきであることが
分る。At this time, if ΔS is positive, it means that the image becomes clearer by increasing the focal length by ΔL, and the image may become clearer by making it slightly longer. On the contrary, if ΔS is negative, it means that the image is blurred by slightly increasing the focal length image formation of the lens, so that the focal length should be further shortened.
従ってこのようにステップ9に於いて△Sの正負を判定
し,正ならばステップ4へ戻ってレンズ結像面間懲を更
に△Lだけ長くするし,もし負ならば,ステップ10に
進めて逆に△Lだけ短くしてステップ5に戻る。Accordingly, in step 9 as described above, the sign of ΔS is judged, and if positive, the process returns to step 4 to further lengthen the lens image plane spacing by ΔL, and if negative, proceed to step 10. On the contrary, the length is shortened by ΔL and the process returns to step 5.
以上のステップを繰り返し行い焦点距離の微小変化によ
る画素濃淡差分和△Sの変化を最大ならしめる如く制御
することによって画像をより鮮明にする。The above steps are repeated to make the image clearer by controlling so as to maximize the change in the pixel density difference sum ΔS due to the minute change in the focal length.
尚上記実施例では横に隣接する画素の濃淡を比較する場
合を示したが,画面に横縞図形を結像する可能性がある
場合は二次差分の積算は,横方向だけでなく縦方向につ
いても行う必要がある。In the above-mentioned embodiment, the case where the shades of the pixels adjacent in the horizontal direction are compared has been shown. However, when there is a possibility that a horizontal stripe figure is formed on the screen, the secondary difference is integrated not only in the horizontal direction but also in the vertical direction. Also need to do.
又画素に分割しそれらの濃淡差の二次差分を積算する領
域としては,目的に応じて夫々適宜設定すればよく,例
えば主として撮映せんとする被写体とその背景に遠近差
がある場合画面全体にわたって前記差分を求めることか
えって必要とする鮮明度を表わさない事になるので,一
般的には画面の中央部の限られた区域について積算する
ことが望ましい。Also, the areas that are divided into pixels and the secondary differences of the grayscale differences are integrated can be set appropriately according to the purpose. For example, when there is a perspective difference between the subject to be imaged and the background, Since the above-mentioned difference is not obtained, it does not represent the required sharpness, so that it is generally desirable to integrate for a limited area in the center of the screen.
しかし逆に上記実施例の如くSSTVにこれを適用する
場合,第2図に示したフローチャートに従った制御は画
面スキャン時間に比べて極めて早くできるから画面全体
にわたって画素分割数を多くして設定し,該画面の水平
方向スキャンごとに焦点調整を行うようにすれば遠近差
のある被写体を全画面にわたって鮮明に写すことが可能
となる。However, conversely, when this is applied to SSTV as in the above embodiment, the control according to the flowchart shown in FIG. 2 can be made extremely quick compared to the screen scan time, so the number of pixel divisions is set to be large over the entire screen. By adjusting the focus for each horizontal scan of the screen, it is possible to clearly capture a subject having a perspective difference over the entire screen.
即ち,画面上方部分が遠方の山岳であり下部にスキャン
するに従って被写体が接近する場合を想定すれば,上述
の如く水平方向への一スキャンごとに焦点調整を補正す
ることによって前記画面の上方部に於いては遠方の山岳
にピントが合い,画面の下部に移動すれば近接する被写
体にピントが合う如く自動的に調整されることになるか
ら被写体に遠近の差がある場合でも全画面にわたって鮮
面に結像せしめることが可能となる。That is, assuming that the upper part of the screen is a distant mountain and the subject approaches as the lower part scans, the upper part of the screen is corrected by correcting the focus adjustment for each horizontal scan as described above. In that case, if you focus on a distant mountain and move to the bottom of the screen, it will be automatically adjusted so that it will focus on a close subject, so even if there is a difference in perspective, the whole screen will be fresh. It becomes possible to form an image on.
尚本発明は以上説明した実施例に限定する必要はなく,
その構成或は制御アルゴリズムは他にも種々考え得るも
のを適用してもよい。又テレビカメラの如くビデオ信号
が介在するもののみならず,通常のカメラであっても一
担画像を電気信号に変換して上述の制御を行なえば本発
明を適用可能なること明らかであろう。The present invention is not limited to the embodiment described above,
As the configuration or control algorithm, various other conceivable ones may be applied. Further, it is apparent that the present invention can be applied not only to a television camera in which a video signal is interposed, but also to a normal camera, if the above-mentioned control is performed by converting a one-shot image into an electric signal.
(発明の効果) 本発明は以上説明した如く,画像そのものの鮮明度を電
気信号に変換してこれを検出しつつ焦点調整を自動的に
行うものであるから応答性に優れ,かつ画像に即した焦
点調整,特にSSTV用カメラに適した自動焦点調整方
法をもたらすうえで著効を奏する。(Effect of the invention) As described above, the present invention converts the sharpness of the image itself into an electric signal and automatically adjusts the focus while detecting the electric signal. It is extremely effective in providing an automatic focus adjustment method suitable for the above-mentioned focus adjustment, especially for SSTV cameras.
第1図は本発明の原理を説明するための図であって,
(a)はピントが合って結像した映像画面を示す図,(b)は
画面を画素に分割し夫々の画素の明暗を数値表示した模
式図,(c)はピントがずれた場合の同様の模式図,(d)は
前記(a)に示した画面中央矢印横列の画素を抜き出した
部分的画素列,(e)は前記(c)に示した画面の同様の画素
列,(f)(g)(h)及び(i)は前記(d)及び(e)に示した画素列
の濃淡一次差分及び2次差分を示す図,第2図は本発明
を適用したSSTV用カメラの自動焦点調整装置の一実
施例を示すブロック図,第3図は前記第2図に示した装
置の制御アルゴリズムの一実施例を示すフローチャート
図である。 1……カメラ,2……作像管, 3……A/D変換器,4……画像メモリ,5……制御
部,6……モータ駆動部,7……モータ。FIG. 1 is a diagram for explaining the principle of the present invention,
(a) is a diagram showing a video screen imaged in focus, (b) is a schematic diagram in which the screen is divided into pixels and the brightness of each pixel is numerically displayed, and (c) is the same as when the focus is out of focus. , (D) is a partial pixel row in which the pixels in the horizontal row of the screen center arrow shown in (a) above are extracted, (e) is the same pixel row on the screen shown in (c) above, and (f) (g), (h) and (i) are diagrams showing the first and second differences in density of the pixel rows shown in (d) and (e), respectively, and FIG. 2 is an automatic view of the SSTV camera to which the present invention is applied. FIG. 3 is a block diagram showing an embodiment of the focus adjusting device, and FIG. 3 is a flow chart diagram showing an embodiment of a control algorithm of the device shown in FIG. 1 ... Camera, 2 ... Image tube, 3 ... A / D converter, 4 ... Image memory, 5 ... Control unit, 6 ... Motor drive unit, 7 ... Motor.
Claims (2)
に調整しピント合せを行う場合の結像鮮明度判断手段に
於いて、前記結像画の全部又は一部を所要数の画素に分
割すると共に、隣接する前記画素の明暗或いは色相の差
分の絶対値を抽出し、これ等の互いに隣接する絶対値の
差分の絶対値を最大ならしめる如く前記レンズと結像面
間の距離若しくは焦点調整手段を制御するようにしたこ
とを特徴とするカメラの自動焦点制御方法。1. An image sharpness determining means for automatically adjusting a distance between a lens of a camera and an image forming surface to perform focusing. The distance between the lens and the image plane is divided into pixels and the absolute value of the difference between the lightness and the hue of the adjacent pixels is extracted, and the absolute value of the difference between the adjacent absolute values is maximized. Alternatively, an automatic focus control method for a camera, characterized in that the focus adjusting means is controlled.
焦点調整手段を前記結像画を映す画面の水平方向への一
スキャン毎に制御するするようにしたことを特徴とする
特許請求の範囲第1項記載の自動焦点制御方法。2. The distance between the lens and the image plane or other focus adjusting means is controlled for each scan in the horizontal direction of the screen on which the image is displayed. 5. An automatic focus control method according to claim 1.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP59244302A JPH0616134B2 (en) | 1984-11-19 | 1984-11-19 | Automatic focus control method for camera |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP59244302A JPH0616134B2 (en) | 1984-11-19 | 1984-11-19 | Automatic focus control method for camera |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS61122617A JPS61122617A (en) | 1986-06-10 |
JPH0616134B2 true JPH0616134B2 (en) | 1994-03-02 |
Family
ID=17116714
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP59244302A Expired - Lifetime JPH0616134B2 (en) | 1984-11-19 | 1984-11-19 | Automatic focus control method for camera |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0616134B2 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS63211470A (en) * | 1986-12-11 | 1988-09-02 | ハネウエル・インコーポレーテツド | Video generator |
JP5171723B2 (en) * | 2009-04-27 | 2013-03-27 | アルプス電気株式会社 | Obstacle detection device and vehicle equipped with the device |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5279945A (en) * | 1975-12-25 | 1977-07-05 | Mitsubishi Electric Corp | Focal regulator |
JPS5413330A (en) * | 1977-07-01 | 1979-01-31 | Olympus Optical Co Ltd | Automatic focus adjusting system |
JPS6024855B2 (en) * | 1981-06-23 | 1985-06-14 | ラッセル株式会社 | net |
-
1984
- 1984-11-19 JP JP59244302A patent/JPH0616134B2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
JPS61122617A (en) | 1986-06-10 |
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