JP4227215B2 - IMAGING DEVICE AND IMAGING DEVICE CONTROL METHOD - Google Patents

Description

ここで、Ωｃとは所望の遮断周波数であり、fc換算した場合には、Ωｃ＝２πfcとなる。
【００３４】
一般にアナログフィルタをデジタルフィルタに変換する手法の一つとして、双１次ｓ−ｚ変換が用いられる。
【００３５】
具体的には、下記（４）式によりｓをｚに変換する。
【００３６】
【数２】

ここでＴとはデジタルフィルタのサンプリング周期である。
【００３７】
上記（４）式を双１次ｓ−ｚ変換すると、下記（５）式になる。
【００３８】
【数３】

この（５）式を下記（６）式と置き換えると
【００３９】
【数４】

下記（７）式となる。
【００４０】
【数５】

実際にはアナログ領域からデジタル領域に写像する際、ずれが生じるのでこれを補正するためにプリワービングと呼ばれる補正を施す。
【００４１】
以上によりサンプリング周期が一定であるとき、遮断周波数を決定すれば上記（６）式により（ａ，ｂ）を算出することができ、遮断周波数を可変できるデジタルハイパスフィルタを実現できる。
【００４２】
上記（７）式をブロック図にすると図１７のようになり、図１３、１４のステップＳ１２０２において実行されている。
【００４３】
図１７において、１５０１は入力データ（Ｓin）、１５０２は１サンプリング前のデータ（Ｚ^-1）、１５０７は第１の乗算処理回路で、（Ｚ^-1）１５０２に定数ａを乗算する。１５０２は第１の加算処理回路で、入力データ（Ｓin）１５０１と、定数ａと１サンプリング前のデータ（Ｚ^-1）１５０２との乗算値、即ちａ×（Ｚ^-1）とを加算する。この出力データをｃとする。１５０８は反転処理回路であり、１サンプリング前のデータ（Ｚ^-1）１５０２の符号を反転する。１５０３は第２の加算処理回路であり、出力データｃと（−Ｚ^-1）とを加算する。１５０４は第２の乗算処理回路であり、(c−Ｚ^-1)と定数bとを乗算する。１５０５はハイパスフィルタの最終的な出力データＳoutであり、第２の乗算処理回路１５０４の出力データである。また、中間データｃは次回の演算のために１サンプリング前のデータ（Ｚ^-1）に保存される。この一連の演算を所定周期で実行することによりハイパスフィルタとなる。
【００４４】
従って、制限動作のためのカットオフ周波数fcを変化させた場合には、フィルタ係数(a,b)を共に算出しなければならず、図１３、１４のように、制御周期が１ｋＨｚという高速の処理では、フィルタ係数も数式によって算出するために、処理能力の高いマイコン（マイクロコンピュータ）の使用や防振専用マイコンを用意しなければならず、高価なシステムになってしまうという問題点があった。
【００４５】
本発明は、上述した従来技術の有する問題点を解消するためになされたもので、その第１の目的とするところは、高価なマイコンを用いることなく制限動作による弊害を防止し得ると共に、自然なカメラワークをあらゆる撮影画角で実現できる撮像方法及び装置を提供することである。
【００４７】
上記目的を達成するために請求項１記載の撮像装置は、撮像装置の制御方法であって、前記撮像装置の振れを検出する振れ検出工程と、前記振れ検出工程により検出された振れ情報に応じて補正動作を行う補正工程と、前記補正工程の補正動作に制限を加えるために帯域制限フィルタのカットオフ周波数に対応する少なくとも２つ以上の変数を有するテーブルデータからデータ選択を行うことで制限動作を行う制御工程とを有し、前記制御工程は、前記補正工程の補正量に応じて目標参照アドレスを決定し、前記目標参照アドレスに近づくように、逐次テーブルデータ参照アドレスを変更するとともに、前記撮像装置の操作状況に応じて前記テーブルデータ参照アドレスの変化量と変化周期とを変更し、前記テーブルデータは、前記テーブルデータ参照アドレスに応じて所定の制限強度特性となるようにデータ決定されていることを特徴とする。
【００４８】
上記目的を達成するために請求項３記載の撮像装置は、撮像装置であって、前記撮像装置の振れを検出する振れ検出手段と、前記振れ検出手段により検出された振れ情報に応じて補正動作を行う補正手段と、前記補正手段の補正動作に制限を加えるために帯域制限フィルタのカットオフ周波数に対応する少なくとも２つ以上の変数を有するテーブルデータからデータ選択を行うことで制限動作を行う制御手段とを有し、前記制御手段は、前記補正手段の補正量に応じて目標参照アドレスを決定し、前記目標参照アドレスに近づくように、逐次テーブルデータ参照アドレスを変更するとともに、前記撮像装置の操作状況に応じて前記テーブルデータ参照アドレスの変化量と変化周期とを変更し、前記テーブルデータは、前記テーブルデータ参照アドレスに応じて所定の制限強度特性となるようにデータ決定されていることを特徴とする。
【００６４】
【発明の実施の形態】
以下、本発明の一実施の形態を図１乃至図１１に基づき説明する。
【００６５】
図１は、本発明の一実施の形態に係る撮像装置の構成を示すブロック図であり、同図は、撮像装置としてのビデオカメラに電子防振機能を搭載した構成を示している。
【００６６】
図１において、レンズ群はインナーフォーカスタイプの構成となっており、第１の固定レンズ１０１、ズームレンズ１０２、絞り１０３、第２の固定レンズ１０４、フォーカスレンズ１０５からなる。前記レンズ群からの光はＣＣＤ等の撮像素子１０６に結像され、増幅器１０７で最適なレベルに増幅された後、カメラ信号処理回路１０８へと入力されて、標準テレビ信号に変換される。
【００６７】
また、図１に示すビデオカメラは電子的な手振れ補正機能を備えており、防振のＯＮ／ＯＦＦはスイッチ１１７の状態を検出することで行っている。角速度センサ１０９（ピッチ方向）、角速度センサ１１０（ヨー方向）でカメラ本体（撮像装置本体）の振れ角速度を検出し、増幅器１１１，１１２でそれぞれ増幅した後、防振制御マイコン（マイクロコンピュータ）１１５のＡ／Ｄコンバータ１１５ａで取り込み、ハイパスフィルタ（ＨＰＦ）１１５ｂでＤＣ成分をカットした角速度信号を積分回路１１５ｄで積分して角変位に変換する。
【００６８】
積分回路１１５ｄで算出された振れ角θに対して、焦点距離補正回路１１５ｅで光学系の焦点距離ｆ分の補正を行い、ｆ×ｔａｎθとなる補正信号を算出する。補正系制御部１１５ｈは焦点距離補正回路１１５ｅの出力信号である補正信号（撮像素子１０６上の振れによる画素移動分に相当）に応じて、振れによる移動方向とは逆方向に動かすことで振れ補正を行う。尚、１１５ｃは帯域制限用のハイパスフィルタ（帯域制限ＨＰＦ）であり、補正信号を補正量規格化回路１１５ｆで規格化して得られた規格化補正量と、ＨＰＦ１１５ｂの出力とに応じて、制限処理制御部１１５ｇが帯域制限ＨＰＦ１１５ｃを制御し、パンニング動作時の防振能力を制限する。この制限動作については後で詳しく説明するが、本発明の特徴として、図１７で説明した帯域制限用フィルタ係数（ａ，ｂ）をカットオフ周波数毎にテーブルデータとしてテーブルデータ記憶部１１５ｉに記憶しており且つこのテーブルデータは、テーブル検索用参照アドレスの変化に対して所定の特性となるように作られている。制限動作時には、このテーブルから所望のカットオフ周波数に対応するフィルタ係数を選択することで、制限強度の変更が行われる。
【００６９】
次に、抽出される画像について図２を用いて説明する。電子的な防振制御で抽出される画像領域は、例えば図２（ａ）における領域２０２となる。第２図（ａ）は撮像素子１０６の撮像画面を表わしており、２０１が全撮像画面の領域に相当する。このうち、一部のみの領域、例えば領域（抽出画面）２０２を抽出し、この領域２０２が図２（ｂ）の領域２０４のように、全画面として表示処理や記録処理が施される。抽出画面２０２は手振れを補正するように位置変更され、図２（ａ）において２０３で示される垂直方向と水平方向の位置座標（Ｖ０，Ｈ０）を変更することで行われる。図２（ａ）の位置座標２０３の位置変更範囲は、領域２０１と領域２０２との水平/垂直の画素数差（以下、余剰画素と記述する）で決定される。また、図２（ａ）の位置座標２０３は、手振れが無い場合の原点座標を定めておき、その原点を基準として、手振れの量と方向に応じて位置座標２０３を変化させることで補正を行うように決定される。
【００７０】
領域２０２を抽出する手法としては、フィールドメモリを用いて領域２０１の画像を一旦記憶し、領域２０２の画像のみを読み出しながら、領域２０１の大きさになるように拡大処理して領域２０４の表示を得る方法と、領域２０２が予め標準ＴＶ信号に必要な走査線数を満足するように、撮像素子１０６として高密度で高画素タイプの大型ＣＣＤを用いる方法とがある。前者、後者共に高価なフィールドメモリや大型ＣＣＤを必要とするので、本実施の形態では、汎用のＰＡＬ用のＣＣＤ（ＰＡＬＣＣＤ）をＮＴＳＣのカメラに用いる構成とする。
【００７１】
ＰＡＬＣＣＤは垂直方向の画素密度が高いので、垂直走査方向はタイミングジェネレータ等のＣＣＤ駆動回路でＮＴＳＣ規格に対しての余分ライン数の範囲内で、高速掃き出しすべきライン数を角変位に応じて変化させれば、垂直方向の切り出し画像の位置を変化させることが可能となる。また、水平走査方向はラインメモリ１１３とメモリ制御回路１１４との構成で縦横比分だけ拡大処理を行ないつつ、ラインメモリ１１３への書き込み開始画素位置と読み出し開始画素位置との関係を変化させれば、水平方向の画面位置変更が行え、安価な振れ補正装置が実現できる。
【００７２】
図１は、そのような補正系の構成になっており、垂直走査方向の画素移動は防振マイコン１１５がＣＣＤ駆動回路１１６を制御して高速掃き出し制御を行わせることで所望の走査領域の抽出行い、水平走査方向の画素移動はカメラ信号処理回路１０８で処理された映像信号を取り込むラインメモリ１１３とメモリ制御回路１１４とで、メモリされた水平走査画像の読み出し位置を振れ補正画素移動量に応じて可変にしながら且つ縦横比に見合うだけ拡大処理（メモリ読み出しレートを変更して、間引いて読み出すことで拡大可能）を行い、その信号をカメラ信号処理回路１０８に戻して色処理等を施すことで標準ＴＶ信号に変換する。
【００７３】
また、防振制御マイコン１１５はズームレンズ１０２、フォーカスレンズ１０５も制御している。押し圧により抵抗値が変化する回転操作タイプのズームスイッチユニット１１８からの信号に応じて、防振制御マイコン１１５は駆動命令をモータドライバ１２０を介してモータ１１９に送ることで、ズームレンズ１０２が移動されて変倍動作が行われる。また、カメラ信号処理回路１０８で処理された焦点信号が最大となるように、防振制御マイコン１１５は駆動命令をモータドライバ１２２を介してモータ１２１に送ることで、フォーカスレンズ１０５が移動されて焦点調節が行われる。
【００７４】
次に図３、４及び図５を用いて、防振制御マイコン１１５で処理される本発明の防振制御動作を説明する。本発明の第１の目的は、簡単な制限動作制御方法でカメラワークや撮影画像に支障をきたさない自然な手振れ補正を実現することにある。本発明の特徴として、帯域制限用フィルタ係数（ａ，ｂ）を、テーブルデータ検索用参照アドレスの変化に対して、所定の特性を満足するようにカットオフ周波数毎のテーブルデータとしてテーブルデータ記憶部１１５ｉに記憶し、制限動作時にはこのテーブルから所望のカットオフ周波数に対応するフィルタ係数を選択することで、制限強度の変更が行われる。また、処理フローの説明は、図１の防振制御マイコン１１５での処理と重複するが、図１ではブロック図として示したが、実際にはプログラムにより処理されており、ここでは改めてプログラムとしての説明を図３、４を用いて行う。
【００７５】
図３、４は、防振制御動作手順を示すフローチャートで、これは、角速度センサ１０９，１１０で検出した角速度信号を積分することで角変位を算出する処理を示している。本処理は防振制御マイコン１１５で実行される定周期割込処理であり、本実施の形態ではフィールド周波数の１０倍、つまりＮＴＳＣの場合６００Ｈｚの周波数で実行される。この周波数は、角速度信号のサンプリング周波数、角変位の算出周波数に相当する。防振制御マイコン１１５での割り込みの起動要因は、例えば、発振クロックの所定分周でアップ(若しくはダウン)カウントしているカウンタが、１／６００ｓｅｃに相当するデータと一致する毎に発生する。また、図１で説明したように角速度信号を防振制御マイコン１１５の図示しないＡ／Ｄコンバータで取り込むが、本実施の形態では、簡単にするため、前記Ａ／Ｄコンバータの動作モードはスキャンモードで、いつでもＡ／Ｄ変換処理動作を繰り返しているものとする。
【００７６】
図３、４において割込処理を開始すると、まず、ステップＳ３０１でＡ／Ｄサンプリングした角速度信号に対してハイパスフィルタ処理をかけることで、ＤＣ成分の影響を除去する。次のステップＳ３０２は、ＡＣ成分の角速度信号に周波数帯域の制限を設ける処理であり、ステップＳ３０２ａからステップＳ３０２ｈで構成される（ステップＳ３０２の詳細な説明については、図５の説明の中で行う）。実際にはステップＳ３０２と同様なハイパスフィルタ処理であり、そのカットオフ周波数がステップＳ３０１では固定値なのに対して、ステップＳ３０２では可変設定が可能になっている。このカットオフ周波数を低域から高域まで変化させることにより、帯域制限が可能になっている。ステップＳ３０２のカットオフ周波数をどのように制御するかは、図５のフローと合わせて後述するが、パンニング動作等のカメラワーク動作中にはカットオフ周波数を上げて防振の抑振能力を低下させるようにし、通常撮影時には手振れ除去のためカットオフ周波数を低下させるように制御される。また、補正可能範囲の限界よりも大きな振れを補正しようとして補正端に衝突したときの画面の不自然さを防止するためにも、帯域制限の制御が実行されている。
【００７７】
次にステップＳ３０３で前記ステップＳ３０２において帯域制限された角速度信号を積分処理し角変位量を算出する。ここで算出された角変位量がカメラ本体（撮像装置本体）に加わる振れ角θに相当する。次にステップＳ３０４で焦点距離補正を行い補正量を算出する。ここで算出される補正量は前述したように、前記ステップＳ３０３において得られた各変位量、即ち振れ角θと光学系の焦点距離ｆに応じてｆ×ｔａｎθとして算出される。
【００７８】
次のステップＳ３０５からステップＳ３０７までの処理は、１フィールド間に１０回、振れ角算出が行われたか否かの判断処理ルーチンである。即ち、ステップＳ３０５で回数パラメータのＲＡＭである「ｍ」をインクリメントし、次のステップＳ３０６で「ｍ＝１０」であるか否か、即ち、１０回割り込みがあったか否かを判断する。そして、１０回割り込みがあった場合は、次のフィールドのためにステップＳ３０７で「ｍ＝０」と初期化を行った後、本処理動作を終了する。
【００７９】
一方、前記ステップＳ３０６において１０回割り込みが無い場合は、前記ステップＳ３０７をスキップして本処理動作を終了する。
【００８０】
なお、前記ステップＳ３０１からステップＳ３０４では、垂直方向の振れ信号処理を角速度センサ１０９の出力であるピッチ方向の角速度信号で行い、水平方向の振れ信号処理を角速度センサ１１０の出力であるヨー方向の角速度信号で行っている。
【００８１】
図５のフローの処理は１フィールドに１回処理され、図３、４のフローの処理が１０回実行されて、次の１回目が実行されるまでの間、つまり現フィールドの最後に実行されることになる。
【００８２】
図５において処理を開始すると、まず、ステップＳ４０１で「ｍ＝０」になるまで、その場で待機する。そして、現フィールドで割り込み処理が１０回行われてｍが初期化された場合は、次のステップＳ４０２で前記図３、４のステップＳ３０４おいて算出された補正量の規格化を行う。
【００８３】
このピッチ規格化補正量及びヨー規格化補正量は、下記（８）式及び（９）式により算出される。
【００８４】
ピッチ規格化補正量＝ピッチ補正量／垂直画素サイズ／垂直余剰画素数／２×１００（％） … （８）
ヨー規格化補正量＝ヨー補正量／水平画素サイズ／水平余剰画素数／２×１００（％） … （９）
本実施の形態では、ＮＴＳＣのカメラにＰＡＬ用のＣＣＤ（５８２Ｖ×７５２Ｈ）を用いるものとした。ここから、ＮＴＳＣ規格の垂直４８５ラインを切り出すと、縦横比から垂直方向の抽出画素は６２７Ｈとなる。従って、余剰画素は９７Ｖ×１２５Ｈとなり、手振れの方向に応じて補正方向が正負をとるので、余剰画素数の１／２で規格化が行われる。
【００８５】
次のステップＳ４０３は、前記ステップＳ４０２において算出された規格化補正量を元に補正能力に制限を加えるための制限量を読み出す参照アドレスを算出する処理であり、ステップＳ４０３ａからステップＳ４０３ｅで構成される。ここで制限量は、帯域制限ハイパスフィルタ１１５ｃのカットオフ周波数に相当するフィルタ係数（ａ，ｂ）である。
【００８６】
まず、ステップＳ４０３ａで規格化補正量に応じた制限目標カットオフ周波数に対応するデータテーブル記憶部１１５ｉ内のデータテーブルの目標参照アドレスＡｎを算出する。この目標参照アドレスＡｎは図６に示す特性で決定される。
【００８７】
図６は、規格化補正量に対する目標参照アドレスＡｎの特性を示す図であり、同図において、横軸は規格化補正量であり、最大補正限界である余剰画素の１／２全てを使用して補正する場合を１００％としている。縦軸はデータテーブル記憶部１１５ｉ内のデータテーブル検索用の参照アドレスである。本実施の形態では、補正量が３０％以上のとき、参照アドレスが比例的に変化する特性としており、補正量が１００％のとき参照アドレスは１２８を選択し、このときのカットオフ周波数が６Ｈｚとなるようにしているが、これは上述した従来例で説明した手振れ周波数が主として５Ｈｚ以下であることによる。
【００８８】
参照アドレスＡｎとカットオフ周波数ｆｃとの関係を図７に示す。同図において、横軸は規格化補正量、縦軸はカットオフ周波数である。同図において、参照アドレスが大きくなるほどカットオフ周波数は大きく設定され、その周波数に応じたフィルタ係数（ａ，ｂ）がデータテーブル記憶部１１５ｉ内のデータテーブルから読み出される。参照アドレスとカットオフ周波数との関係は、従来例の図１３と同様に２乗の関数でカットオフが変化する特性としており、振れ角が大きくなって補正端に衝突した撮像画像が乱れる現象を防止するためにも、図６の特性は、補正比率が最大補正限界に近いほど、より急峻にカットオフを高くする設定となっている。
【００８９】
図８は、データテーブル記憶部１１５ｉ内のデータテーブルの一例を示す図であり、データテーブル記憶部１１５ｉ内には、参照アドレスに応じてフィルタ係数ａ（Ａｎ）、ｂ（Ａｎ）の２つの変数がデータ列として格納されており、必要なカットオフ周波数に関して予めフィルタ係数ａ（Ａｎ）、ｂ（Ａｎ）が算出されて作られている。なお、図８に示すデータテーブルは、上記図１７で説明したハイパスフィルタの乗算係数であり、この構成を図９に示す。
【００９０】
図９において、８０１は入力データ（Ｓｉｎ）、８０６は１サンプリング前のデータ（Ｚ^-1）の格納部、８０７は第１の乗算処理回路で、フィルタ係数ａ（Ａｎ）を乗算する。８０２は第１の加算処理回路で、入力データ（Ｓｉｎ）８０１と、フィルタ係数ａ（Ａｎ）と格納部８０６内の１サンプリング前のデータ（Ｚ^-1）との乗算値とを加算する。この出力データをｃとする。８０８は反転処理回路で、格納部８０６内の１サンプリング前のデータ（Ｚ^-1）の符号を反転する。８０３は第２の加算処理回路で、前記出力データｃと符号反転された１サンプリング前のデータ（−Ｚ^-1）とを加算する。８０４は第２の乗算処理回路で、（ｃ−Ｚ^-1）とフィルタ係数ｂ（Ａｎ）とを乗算する。８０５はハイパスフィルタの最終的な出力データ（Ｓｏｕｔ）であり、第２の乗算処理回路８０４の出力である。また、中間データ（出力データ）ｃは次回の演算のために格納部８０６内の１サンプリング前のデータ（Ｚ^-1）に保存される。この一連の演算を所定周期で実行することによりハイパスフィルタとなる。
【００９１】
図９に示すように、パンニングに伴う補正量の変化に応じて参照アドレスを決定し、これに応じてデータテーブル記憶部１１５ｉ内のデータテーブルからフィルタ係数ａ（Ａｎ）、ｂ（Ａｎ）を選択することにより、カットオフ周波数を変えることが可能となる。
【００９２】
再び図５に戻って、ステップＳ４０３ｂで前記ステップＳ４０３ａにおいて算出された目標参照アドレスＡｎが現在の参照アドレスＡｎ以上か否かを判断する。そして、目標参照アドレスＡｎが現在の参照アドレスＡｎ以上である場合は、ステップＳ４０３ｅで「解除フラグ」をクリアした後、ステップＳ４０４へ進む。ここで解除フラグは、パンニング動作が終了したときにセットされるフラグであり、このフラグがセットされるまではカットオフ周波数を下げないように、つまり参照アドレスＡｎを小さくしないように、図３、４のステップＳ３０２内で制御される。これは、制限強度を弱くして防振効果を高めることを禁止している処理であり、制限動作のハンチングを防止するために行われる。
【００９３】
一方、前記ステップＳ４０３ｂにおいて目標参照アドレスＡｎが現在の参照アドレスＡｎより小さいと判断された場合は、ステップＳ４０３ｃでパンニング動作が終了したか否かを判断するため、ハイパスフィルタ１１５ｂの出力角速度信号が所定値γより小さいか否かを判断する。ハイパスフィルタ１１５ｂの出力信号は、帯域制限や焦点距離補正が行われる前の信号であるので、撮影画角に依らず直接カメラの振れの検出が行え、制限動作のハンチングや画角毎の応答性の違いを防止することが可能となる。
【００９４】
なお、所定値γは、パンニング動作終了時のハイパスフィルタ１１５ｂの出力レベルを予め測定することで決定されている。
【００９５】
前記ステップＳ４０３ｃにおいてハイパスフィルタ１１５ｂの出力の絶対値が所定値γ以上の場合は、パンニング動作継続中であると判断して前記ステップＳ４０３ｅへ進み、また、ハイパスフィルタ１１５ｂの出力の絶対値が所定値γ以上でない場合は、ステップＳ４０３ｄで「解除フラグ」をセットする。なお、通常の手持ち撮影時には制限がかからないので、前記ステップＳ４０３ｂにおいて目標参照アドレスＡｎと現在の参照アドレスＡｎとが等価となり、「解除フラグ」はクリア状態のままとなっている。
【００９６】
このようにパンニング動作時の撮影状況判断が行われる中、制限動作は図３、４のステップＳ３０２内で制御される。図３、４のステップＳ３０２ａで目標参照アドレスＡｎと現在の参照アドレスＡｎとが等しいか否かを判断し、等しい場合はステップＳ３０２ｈへ進み、現在と同じカットオフ周波数のフィルタ係数ａ（Ａｎ）、ｂ（Ａｎ）をテーブルから読み出して、改めて帯域制限ＨＰＦ１１５ｃに係数設定を行った後、ステップＳ３０３へ進む。
【００９７】
一方、前記ステップＳ３０２ａにおいて目標参照アドレスＡｎと現在の参照アドレスＡｎとが等しくない場合は、ステップＳ３０２ｂで現在の参照アドレスＡｎが目標参照アドレスＡｎより小さいか否かを判断する。そして、現在の参照アドレスＡｎが目標参照アドレスＡｎより小さい場合は、現在の参照アドレスＡｎが目標参照アドレスＡｎ至っていない場合であり、図５のステップＳ４０３においては制限を強くするべきと判断している場合である。この場合は、図３、４のステップＳ３０２ｇで参照アドレスＡｎを現在値から所定値α分だけ大きくした後、ステップＳ３０２ｈへ進む。
【００９８】
一方、前記ステップＳ３０２ｂにおいて目標参照アドレスＡｎが現在の参照アドレスＡｎより小さい場合は、次のステップＳ３０２ｃで「解除フラグ」がセット状態であるか否かを判断する。そして、解除フラグがクリアの場合には、カットオフ周波数を下げないように参照アドレスを現在値に保持した後、ステップＳ３０２ｈへ進む。
【００９９】
一方、前記ステップＳ３０２ｃにおいて解除フラグ＝１の場合は、パンニング動作が終了してカットオフ周波数を小さくしても構わない場合なので、ステップＳ３０２ｄで回数カウンタＣ０をインクリメントして、ステップＳ３０２ｅで回数カウンタＣ０が偶数であるか否かを判断する。そして、回数カウンタＣ０が偶数ではなく奇数である場合は、ステップＳ３０２ｈへ進み、回数カウンタＣ０が偶数である場合は、ステップＳ３０２ｆで参照アドレスの設定を現在値より所定値βだけ小さい値にする。この回数カウンタＣ０は、パンニング動作終了時のカットオフ周波数の変化が少なくなるように、参照アドレスＡｎの変化周期をパンニング動作開始時に比べて遅くするためのものである。そして、ステップＳ３０２ｈで再設定された参照アドレスＡｎに応じたフィルタ係数を読み出して、帯域制限ＨＰＦ１１５ｃの設定を更新する。
【０１００】
図５の処理がフィールド周期で実行される中、図３、４の処理は１フィールドに１０回行われ、ステップＳ３０２ｆ、ステップＳ３０２ｇで用いられる所定値α、β分の変化率で且つ回数カウンタＣ０が偶数となる周期で参照アドレスＡｎの増減が制御される。ここで、変化率を決定する所定値は、例えば図１０及び図１１のような制限強度変化特性となるように決定されている。図１０及び図１１において、横軸は時間であり、縦軸はカットオフ周波数である。
【０１０１】
図１０は、パンニング動作（撮影）開始時のカットオフ周波数の変化特性を示す図で、時間９０１の時点からパンニング動作が開始された例を示している。パンニング動作開始時には、素早い応答性で目標のカットオフ周波数にならなければ、補正限界に衝突するような端当たりが発生する可能性がある。また、パンニング動作中には撮影画面が流れているので、カットオフ周波数を急激に変化させても画面上の乱れは生じない。従って、パンニング動作開始時には、時間９０２の時点のように短時間で目標制限量となるように所定値αは大きめの値となる。
【０１０２】
図１１は、時間９０３の時点でパンニング動作が終了した場合を示している。時間９０３の時点以降は、撮影画面は静止状態に近いので、カットオフ周波数の急激な変化は画面上の動きとなってしまい、また、パンニング動作終了後、直ちに補正能力を上げると振れ戻しが生じてしまう。これらの問題を解消するためにも、パンニング動作終了時には応答性を低下させ、曲線９０４のようにゆっくりとカットオフ周波数が変化するように所定値βが決定され、変化周期がパンニング動作開始時に比べて２倍となっている。
【０１０３】
本実施の形態では、パンニング動作終了時の参照アドレスの変化周期は、パンニング動作開始時に比べて２倍としたが、これに限られるものではなく、振れ戻しや帯域制限変化が画面に違和感を与えないように設定されていれば良い。
【０１０４】
また、本実施の形態では、所定値α、βを共に定数とし、参照アドレスが線形的に変化するような手法を用いた。この手法により、帯域制限の狙いであるカットオフ周波数は、結果として図７の特性で変化することになり、補正量に応じた制限目標カットオフ周波数も目標カットオフ周波数に至る変化軌跡も同一の特性で変化させることが可能となるので、上述した図１５の１３０３のような変化軌跡にはならず、カットオフ周波数の変化で画面上に支障をきたすことを防止することができる。
【０１０５】
また、参照アドレスの加減算という簡単な演算で制御動作処理を実現することが可能となり、より安価なマイコンを使用したシステム構成とすることができる。
【０１０６】
再び図５に戻って、ステップＳ４０４で図３、４のステップＳ３０３において算出された補正信号（ｆ×ｔａｎθ）を基に、切り出し位置の目標位置座標（Ｖ０，Ｈ０）を算出する。 ここで目標位置ＶＯ，ＶＨは下記（１０）式及び（１１）式により算出され、振れ補正で移動させるべき画素数が得られる。
【０１０７】
Ｖ０＝垂直の原点位置±ピッチ方向の振れ角を補正する移動画素数
＝垂直の原点位置±（−１）×ピッチ補正量／垂直画素サイズ…（１０）
Ｈ０＝垂直の原点位置±ヨー方向の振れ角を補正する移動画素数
＝垂直の原点位置±（−１）×ヨー補正量／水平画素サイズ …（１１）
次に、ステップＳ４０５で前記ステップＳ４０４において算出された目標位置座標（Ｖ０，Ｈ０）を切り出し位置として、ＣＣＤ駆動回路１１６及びメモリ制御回路１１４に命令を出力した後、次のフィールド用に前記ステップＳ４０１へ戻り、１０回の積分処理が行われるまで待機するように制御される。
【０１０８】
上述したように本実施の形態によれば、制限動作を行うためのカットオフ周波数に応じて所定特性となる複数の帯域制限データをＲＯＭテーブルとして持ち、テーブルデータ参照アドレスを振れ補正量に応じて制御し且つテーブルデータ参照アドレスの変化量と変化周期とをカメラ操作状態に応じて変更することにより、安価なマイコンの選択や他の処理との複合処理が可能となり、また、パンニング動作開始時の制限動作の応答性を高めたり、パンニング動作終了時に発生しやすい振れ戻し現象を防止することが可能となる。更に、制限強度や制限強度変化率を同一の特性で決定することが可能となり、パンニング動作時に制限強度変化による画面の動きを防止できると共に、自然なカメラワークをあらゆる撮影画角で実現することが可能となる。
【０１０９】
なお、本実施の形態においては、ＰＡＬ用ＣＣＤとラインメモリとを使用した構成について説明したが、フィールドメモリを使用して抽出画像位置を制御することにより補正しても良いし、また、拡大制御しなくても済む大型或いは超高画素タイプのＣＣＤを使用しても良いし、更には、光学式の補正手段であっても良い。
【０１１０】
また、本実施の形態においては、振れ検出手段として角速度センサを用いたが、これに限られるものではなく加速度センサでも良く、その場合は防振マイコン内部または外部で更に１回積分処理を行えば良い。
【０１１１】
また、本実施の形態においては、振れ角変位量の算出はソフトウェア処理として説明したが、ハードウェアにより構成しても良い。
【０１１２】
更に、本実施の形態においては、制限手段としてハイパスフィルタによる帯域制限を例示したが、積分回路１１５ｄでの積分帰還係数やゲイン係数をテーブルデータ化し、積分処理で帯域制限しても良い。
【０１１３】
【発明の効果】
以上詳述したように、本発明の撮像装置および撮像装置の制御方法によれば、帯域制限フィルタのカットオフ周波数に対応する少なくとも２つ以上の変数を有するテーブルデータからデータ選択を行うことで、帯域制限に関わる複数のデータを同時に取得することができ、前記データの算出のための演算時間を省くことが可能となるので、高速で処理される防振制御であっても安価なマイコンを選択することができ且つ他の処理（焦点調節や露出調節等）を並列処理できるようになり、簡素なシステムを選択することが可能となるという効果を奏する。
【０１１４】
また、本発明の撮像装置および撮像装置の制御方法によれば、データテーブル参照アドレスの変化量と変化周期とを、撮影状況に応じて変更することより、パンニング動作開始時の制限動作を素早く行うことができ且つパンニング動作終了時に発生しやすい振れ戻し現象を防止することができるという効果を奏する。
【０１１５】
また、本発明の撮像装置および撮像装置の制御方法によれば、特に、制限動作制御は、所定特性のデータテーブルからのデータ選択で目標値を決定し、該目標値に近付くように逐次参照アドレスの決定が行われるので、制限強度や制限強度変化率を同一の特性で決定することが可能となり、パンニング動作時に制限強度変化による画面の動きを防止することができると共に、自然なカメラワークをあらゆる撮影画角で実現することができるという効果を奏する。
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る撮像装置の構成を示すブロック図である。
【図２】本発明の一実施の形態に係る撮像装置において電子的な防振制御で抽出される画像領域を説明するための図である。
【図３】本発明の一実施の形態に係る撮像装置の防振制御動作手順を示すフローチャートである。
【図４】本発明の一実施の形態に係る撮像装置の防振制御動作手順を示すフローチャートである。
【図５】本発明の一実施の形態に係る撮像装置の防振制御動作手順を示すフローチャートである。
【図６】本発明の一実施の形態に係る撮像装置における補正量と参照アドレスとの関係を示す図である。
【図７】本発明の一実施の形態に係る撮像装置における参照アドレスとカットオフ周波数との関係を示す図である。
【図８】本発明の一実施の形態に係る撮像装置におけるデータテーブル記憶部内のデータテーブルの一例を示す図である。
【図９】本発明の一実施の形態に係る撮像装置における帯域制限処理部の構成を示すブロック図である。
【図１０】本発明の一実施の形態に係る撮像装置におけるパンニング動作（撮影）開始時のカットオフ周波数の変化特性を示す図である。
【図１１】本発明の一実施の形態に係る撮像装置におけるパンニング動作（撮影）終了時のカットオフ周波数の変化特性を示す図である。
【図１２】従来の撮像装置の構成を示すブロック図である。
【図１３】従来の撮像装置における処理動作手順を示すフローチャートである。
【図１４】従来の撮像装置における処理動作手順を示すフローチャートである。
【図１５】従来の撮像装置における規格化補正量とカットオフ周波数との関係を示す図である。
【図１６】従来の撮像装置における焦点距離と有効像円径の大きさとの関係及び焦点距離と最大補正範囲との関係を示す図である。
【図１７】従来の撮像装置における帯域制限処理部の構成を示すブロック図である。
【符号の説明】
１０１ 第１の固定レンズ
１０２ ズームレンズ
１０３ 絞り
１０４ 第２の固定レンズ
１０５ フォーカスレンズ
１０６ 撮像素子
１０７ 増幅器
１０８ カメラ信号処理回路
１０９ 角速度センサ（ピッチ方向）
１１０ 角速度センサ（ヨー方向）
１１１ 増幅器
１１２ 増幅器
１１３ ラインメモリ
１１４ メモリ制御回路
１１５ 防振制御マイコン
１１５ａ Ａ／Ｄコンバータ
１１５ｂ ＨＰＦ（ハイパスフィルタ）
１１５ｃ 帯域制限ＨＰＦ（ハイパスフィルタ）
１１５ｄ 積分回路
１１５ｅ 焦点距離補正回路
１１５ｆ 補正量規格化回路
１１５ｇ 制限処理制御部
１１５ｈ 補正系制御部
１１５ｉ テーブルデータ記憶部
１１６ ＣＣＤ駆動回路
１１７ スイッチ
１１８ ズームスイッチユニット
１１９ モータ
１２０ モータドライバ
１２１ モータ
１２２ モータドライバ[0001]
BACKGROUND OF THE INVENTION
The present invention is imaging Apparatus and control method for controlling imaging apparatus About.
[0002]
[Prior art]
2. Description of the Related Art In recent years, imaging devices such as video cameras are generally equipped with an anti-shake function equipped with an anti-shake function. As a method of the camera shake prevention function, there are optical camera shake correction and electronic camera shake correction.
[0003]
In optical camera shake correction, a prism or lens member capable of optical axis displacement is arranged in the middle of the optical path of the photographic light incident on the image sensor, and the optical axis is displaced according to the camera shake to perform camera shake correction. . As the hand shake detection means used in the optical system, an angular velocity sensor such as a vibration gyroscope is used to detect the shake component directly applied to the image pickup device, and this detection output is integrated to detect the angular displacement of the image pickup device. Has become commonplace.
[0004]
On the other hand, electronic image stabilization is often used in combination with a motion vector detection method in which the amount of motion of the imaging device is calculated from a change in the video signal between fields and used as a shake signal. The stored image is corrected by extracting a part of the memory image so that the motion is removed.
[0005]
As another system for electronic camera shake correction, a sensor is used for shake detection, and only a part of the image received by the image sensor is cut out, and the shake position is controlled according to the detected shake. A type of correction has also appeared.
[0006]
In the case of electronic camera shake correction, since the video signal is electrically corrected, the correction cycle is a field cycle, and the camera shake during the exposure time cannot be removed, but it can be smaller and lighter than the optical method. There is. In addition, by using a high-density large-sized image pickup device, the resolution of a captured image extracted or extracted from a memory is increased, and image quality degradation that is disadvantageous compared to the optical type is being improved.
[0007]
By the way, in a video camera, there are cases where shooting is performed while performing camera work such as panning operation and tilting operation that intentionally moves the camera. When shooting with these camera works, camera shake correction is limited so that the correction capability decreases, preventing disturbance of the shot image caused by hitting the end of the correction range, and quickly in the direction intended by the photographer The inventor has proposed a method for achieving a response.
[0008]
12, FIG. 13, FIG. 14, FIG. 15, FIG. 16 and FIG. 17 are diagrams for explaining a limiting method during a panning operation proposed by the present inventors. This restriction method is a technique that allows easy setting of the characteristic of the restriction amount regardless of the focal length and the case where the correction limit changes depending on the focal length. The correction function system will be described as an example.
[0009]
FIG. 12 shows a configuration of an image pickup apparatus including a system for preventing vibration by moving a shift lens for camera shake correction perpendicularly to the optical axis. In the drawing, the lens group has an inner focus type configuration, and includes a fixed lens 1101, a zoom lens 1102, an aperture 1103, a vibration-proof shift lens 1104, and a focus lens 1105. The light from this lens group forms an image on an image sensor 1106 such as a CCD. An image on the image sensor 1106 is photoelectrically converted, amplified to an optimum level by an amplifier 1118, and then input to a camera signal processing circuit 1119 to be converted into a standard television signal.
[0010]
Further, the image pickup apparatus of FIG. 12 has an optical camera shake correction function, and the image stabilization is turned on / off by detecting the state of the switch 1120. An angular velocity sensor 1121 (pitch direction) and an angular velocity sensor 1122 (yaw direction) detect the shake angular velocity of the image pickup apparatus main body, and after amplification by amplifiers 1123 and 1124, respectively, an A / D converter (not shown) of a control microcomputer (control microcomputer) 1116 The angular velocity signal is integrated by the internal processing of the control microcomputer 1116 and converted into angular displacement. Based on the obtained angular displacement, that is, the shake angle θ and the focal length f of the optical system, the control microcomputer 1116 shifts the amount of movement of the captured image due to the shake on the image sensor 1106 (equivalent to approximately f × tan θ) due to the shake. The shake correction is performed by moving the shift lens 1104 perpendicular to the optical axis so as to move in the direction opposite to the moving direction. The control microcomputer 1116 outputs a correction target. The adder 1115 compares the position signal of the shift lens 1104 (the position signal obtained by amplifying the detection signal of the encoder 1113 to a predetermined level by the amplifier 1114) with the correction target value signal from the control microcomputer 1116, and the difference between them is zero (0 ) Is output to the motor 1111 via the motor driver 1112 so that the position of the shift lens 1104 is loop-controlled to match the target position.
[0011]
The control microcomputer 1116 also controls the zoom lens 1102 and the focus lens 1105. The control microcomputer 1116 sends a drive command to the motor 1107 via the motor driver 1108 in response to a signal from the rotary operation type zoom switch unit 1117 whose resistance value is variable by the pressing pressure, so that the zoom lens 1102 moves and changes. Double operation is performed. Further, the control microcomputer 1116 sends a drive command to the motor 1109 via the motor driver 1110 so that the focus lens 1105 moves and adjusts the focus so that the focus signal processed by the camera signal processing circuit 1119 is maximized. Is done.
[0012]
Next, the anti-vibration control flow processed by the control microcomputer 1116 will be described with reference to FIGS. The correction amount is standardized by the focal length and the maximum correction limit, and the limit amount can be calculated with a predetermined characteristic according to the standardized correction amount, so it can handle all focal length changes with only one type of characteristic. It has become.
[0013]
The flowcharts of FIGS. 13 and 14 are processes for calculating the angular displacement by integrating the angular velocity signals detected by the angular velocity sensors 1121 and 1122, and calculating the correction amount and the limit amount. 13 and 14 is a periodic interrupt process executed by the control microcomputer 1116, and is executed at a frequency of 1 kHz, for example. An interrupt activation factor occurs, for example, every time a counter that counts up (or down) with a predetermined frequency division of an oscillation clock matches data corresponding to 1 msec. As described with reference to FIG. 12, the angular velocity signal is captured by the A / D converter of the control microcomputer 1116. In this embodiment, for the sake of simplicity, the operation mode of the A / D converter is the scan mode. Assume that the / D conversion operation is repeated.
[0014]
When the interruption process is started, the influence of the DC component is removed by applying a high-pass filter process to the angular velocity signal A / D sampled in step S1201 of FIGS. The next step S1202 is processing for limiting the frequency band of the angular velocity signal of the AC component, and includes steps S1202a to S1202e (detailed description of step S1202 will be described later). Actually, the high-pass filter processing is the same as that in step S1201, and the cutoff frequency is a fixed value in step S1201, whereas variable setting is possible in step S1202. The band can be limited by changing the cut-off frequency from the low range to the high range. In step S1202, the cut-off frequency is controlled. During camera work operations such as panning, the cut-off frequency is increased to reduce the image stabilization capability. In normal shooting, the cut-off frequency is set to eliminate camera shake. I try to lower it. Further, in order to correct a shake larger than the limit of the correctable range, band limitation control is executed in order to prevent unnaturalness of the screen when colliding with the correction end.
[0015]
Next, in step S1203, the angular velocity signal is calculated by integrating the angular velocity signal band-limited in step S1202. The calculated angular displacement corresponds to a deflection angle applied to the imaging apparatus main body. In step S1204, the focal length change is corrected and a correction amount is calculated. The correction amount is f × tan θ according to the angular displacement obtained in step S1203, that is, the deflection angle θ and the focal length f of the optical system. Next, in step S1205, the correction amount calculated in step S1204 is normalized with the maximum correction limit (movement limit of the shift lens 1104).
[0016]
The pitch normalization correction amount and the yaw normalization correction amount are calculated by the following equations (1) and (2), respectively.
[0017]
Pitch normalization correction amount = Pitch correction amount / Pitch maximum shift limit / 2 × 100 (%) (1)
Yaw normalized correction amount = Yaw correction amount / Yaw maximum shift limit / 2 × 100 (%) (2)
The next step S1206 is a process of calculating a limit amount for limiting the correction capability based on the normalized correction amount calculated in step S1205, step S1206. a to step S1206e. Here, the limit amount corresponds to the cut-off frequency described in the band limiting process in step S1202.
[0018]
First, in step S1206a, a limited target cutoff frequency fc corresponding to the normalized correction amount is calculated. This limited target cutoff frequency fc is determined by the characteristics shown in FIG.
[0019]
FIG. 15 shows the characteristic of the limit amount with respect to the correction amount, that is, the cutoff frequency. In the figure, the horizontal axis is the normalized correction amount, and the ratio of the correction amount necessary for correcting the current shake relative to the case where the correction is performed by shifting to half of the maximum shift limit as 100%. Show. In addition, the vertical axis represents a cut-off frequency for band limitation, which is a parameter for limiting amount. The degree of restriction on the correction amount is not a setting based on a threshold value but a function setting. For this reason, even when the cutoff frequency is controlled to cope with the panning operation, smooth switching can be performed.
[0020]
In the present embodiment, the maximum cut-off frequency is 6 Hz. This is because the main hand-shake frequency component is 5 Hz or less. The band limitation characteristics are set so that the cutoff changes as a square function. The larger the correction amount, the higher the cutoff frequency, and the cutoff when the correction amount is near zero (0). Is controlled to be as low as possible and to improve the anti-vibration (vibration) effect. If you want to enlarge the range where the vibration isolation effect is high (the range where the correction amount is near zero) as much as possible, you can increase the order that was the square of the correction amount, and when the correction amount becomes larger, cut A coefficient or the like may be set so that the off state rises sharply.
[0021]
Here, the maximum shift limit is determined as shown in FIG. 16, and FIG. 16A shows how the effective image circle diameter changes with respect to the change in focal length, and FIG. This shows how the maximum correction range (maximum shift limit) changes with respect to the focal length change. In FIG. 16A, reference numeral 1401 denotes a point where the mechanical maximum movement limit distance of the shift lens 1104 is converted into an effective image circle diameter. Reference numeral 1402 indicates that vignetting does not occur on the photographing screen even if the shift lens 1104 is mechanically moved at the maximum focal length at all focal lengths from wide to telephoto. Therefore, the maximum correction range for 1402 is a constant value such as 1405.
[0022]
On the other hand, when the effective image circle diameter is larger than 1401 only on the telephoto side from the focal length 1404 as in 1403, if the shift lens 1104 is shifted to the maximum position at which it can be mechanically moved on the wide side from 1404, photographing is performed. It means that vignetting occurs on part of the screen. Accordingly, the maximum correction range with respect to 1403 decreases as the focal length 1404 becomes wider as 1406. In general, the lens optical system is often designed as in 1403 to reduce the size of the lens. As described above, even when the maximum correction range changes as indicated by 1406 depending on the focal length, the correction amount is normalized by the maximum correction range, so that the limiting characteristic is not changed for each focal length (characteristic Even without a large number of change parameters, it is possible to prevent end collision and make a transition to and release from a smooth panning operation.
[0023]
13 and 14 again, it is determined in step S1206b whether the limited target cutoff frequency fc calculated in step S1206a is equal to or higher than the current cutoff frequency fc. If the restriction target cut-off frequency fc ≧ the current cut-off frequency fc, the “release flag” is cleared in step S1206e, and then the process proceeds to step S1207. Here, the release flag is a flag that is set when the panning operation is completed, and is controlled in step S1202 so as not to lower the cutoff frequency fc until this flag is set. In other words, it is prohibited to weaken the restriction strength and enhance the vibration isolation effect, thereby preventing the hunting of the restriction operation.
[0024]
On the other hand, if it is determined in step S1206b that the limited target cutoff frequency fc is smaller than the current cutoff frequency fc, the process in step S1201 is performed in order to determine whether the panning operation is completed in step S1206c. It is determined whether or not the subsequent angular velocity signal has become smaller than a predetermined value γ. Since this angular velocity signal is a signal before band limitation and focal length correction are performed, camera shake can be detected directly regardless of the shooting angle of view, and hunting for limiting operations and differences in responsiveness for each angle of view can be detected. It becomes possible to prevent. The predetermined value γ is determined by measuring in advance the angular velocity signal level at the end of the panning operation. If the absolute value of the angular velocity signal is greater than or equal to the predetermined value γ in step S1206c, it is determined that the panning operation is continuing, and the process proceeds to step S1206e. If the absolute value of the angular velocity signal is less than or equal to the predetermined value γ, After determining that the panning operation is completed and setting a “release flag” in step S1206d, the process proceeds to step S1207. Note that since no restriction is applied during normal hand-held shooting, the restriction target cutoff frequency fc and the current cutoff frequency fc are equivalent in step S1206b, and the “release flag” remains in the clear state.
[0025]
As described above, while the shooting situation determination during the panning operation is performed, the limiting operation is controlled in step S1202. That is, it is determined in step S1202a whether the limited target cutoff frequency fc is equal to the current cutoff frequency fc. If they are equal, the process proceeds to step S1204 and the cutoff frequency is not changed. If the limited target cutoff frequency fc is not equal to the current cutoff frequency fc in step S1202a, it is determined in step S1202b whether the current cutoff frequency fc is smaller than the limited target cutoff frequency fc. If it is smaller, the current value has not yet reached the target value, and it is determined in step S1206 that the limit should be increased. In this case, after the cutoff frequency fc is increased from the current value by a predetermined value α in step S1202e, the process proceeds to step S1203.
[0026]
On the other hand, if the limited target cutoff frequency target fc is smaller than the current cutoff frequency fc in step S1202b, it is determined in step S1202c whether the “release flag” is set. If the release flag is clear, the current value is maintained without lowering the cutoff frequency, and the process proceeds to step S1203.
[0027]
On the other hand, if the release flag = 1 in step S1202c, the panning operation may be terminated and the cut-off frequency may be reduced. Therefore, in step S1202d, the cut-off frequency is set by a predetermined value β from the current value. After the value is made smaller, the process proceeds to step S1203.
[0028]
The limit target cut-off frequency fc determined in step S1206 is set so as to gradually approach in the next band limiting process, and the angular velocity signal is limited. For example, when the calculated cut-off is large, the correction effect is reduced with respect to the shake of the hand shake frequency equal to or lower than the cut-off frequency.
[0029]
In step S1207, the shift target value command calculated in step S1205 is output to the adder 1115, and then the processing operation ends.
[0030]
[Problems to be solved by the invention]
However, in the panning operation control of the above-described conventional example, the limit target cutoff frequency fc that is the limit amount is determined according to the correction amount standardized in the maximum correction range of the correction unit, but the cut to the target value is performed. Since the OFF change depends on a predetermined value, for example, a change locus 1303 is drawn from the current cutoff frequency (fc) 1301 to the limited target cutoff frequency (fc) 1302 in FIG. Changes were visible on the screen. That is, since the target value determination and the target value arrival according to the trajectory of the limiting characteristics in FIG. 15 are not performed, there is a case where a change in the cutoff frequency is visible on the screen.
[0031]
In the band-limited high-pass filter process performed in step S1202 of FIGS. 13 and 14, two filter variables actually change with respect to the cutoff frequency fc. One is a parameter for determining the cut-off frequency, and the other is a parameter for setting the gain at the cut-off frequency to 0 dB.
[0032]
This will be described in detail with reference to FIG. In the analog filter, the transfer function of the primary Butterworth high-pass filter is calculated by the following equation (3).
[0033]
[Expression 1]

Here, Ωc is a desired cutoff frequency, and when converted to fc, Ωc = 2πfc.
[0034]
In general, bilinear sz conversion is used as one method for converting an analog filter into a digital filter.
[0035]
Specifically, s is converted to z by the following equation (4).
[0036]
[Expression 2]

Here, T is the sampling period of the digital filter.
[0037]
When the above equation (4) is bilinear sz transformed, the following equation (5) is obtained.
[0038]
[Equation 3]

If this equation (5) is replaced with the following equation (6)
[0039]
[Expression 4]

The following equation (7) is obtained.
[0040]
[Equation 5]

Actually, when mapping from the analog domain to the digital domain, a shift occurs, and therefore correction called pre-working is performed to correct this.
[0041]
As described above, when the cut-off frequency is determined when the sampling period is constant, (a, b) can be calculated by the above equation (6), and a digital high-pass filter capable of varying the cut-off frequency can be realized.
[0042]
FIG. 17 is a block diagram of the above equation (7), which is executed in step S1202 of FIGS.
[0043]
In FIG. 17, 1501 is the input data (Sin), 1502 is the data before one sampling (Z ^-1 ), 1507 is a first multiplication processing circuit, and (Z ^-1 ) 1502 is multiplied by a constant a. Reference numeral 1502 denotes a first addition processing circuit, which is input data (Sin) 1501, a constant a and data before one sampling (Z ^-1 ) 1502 multiplied by, that is, a × (Z ^-1 ) And add. Let this output data be c. Reference numeral 1508 denotes an inversion processing circuit, which is data (Z ^-1 ) Invert the sign of 1502. Reference numeral 1503 denotes a second addition processing circuit, which outputs data c and (−Z ^-1 ) And add. Reference numeral 1504 denotes a second multiplication processing circuit (c−Z ^-1 ) And a constant b. 1505 is final output data Sout of the high-pass filter, which is output data of the second multiplication processing circuit 1504. Further, the intermediate data c is used as data (Z ^-1 ). By executing this series of calculations at a predetermined cycle, a high-pass filter is obtained.
[0044]
Therefore, when the cut-off frequency fc for the limiting operation is changed, both the filter coefficients (a, b) must be calculated, and the control cycle is as high as 1 kHz as shown in FIGS. In processing, since the filter coefficient is also calculated using mathematical formulas, it is necessary to use a microcomputer (microcomputer) with a high processing capacity or a dedicated anti-vibration microcomputer, resulting in an expensive system. .
[0045]
The present invention has been made in order to solve the above-described problems of the prior art. The first object of the present invention is to prevent adverse effects caused by the limiting operation without using an expensive microcomputer and to prevent natural problems. It is an object to provide an imaging method and apparatus capable of realizing various camera work at any shooting angle of view.
[0047]
Up Note To achieve the goal Claim 1 The imaging device A method for controlling an imaging apparatus, comprising: A shake detection step for detecting shake, a correction step for performing a correction operation in accordance with shake information detected by the shake detection step, and a restriction on the correction operation in the correction step Corresponds to the cutoff frequency of the band limiting filter A control step of performing a restriction operation by selecting data from table data having at least two or more variables, the control step determines a target reference address according to a correction amount of the correction step, Sequentially change the table data reference address so that it approaches the target reference address And according to the operation status of the imaging device table Change data reference address change amount and change cycle The table data is determined so as to have a predetermined limit strength characteristic according to the table data reference address.
[0048]
Up Note To achieve the goal Claim 3 The imaging device An imaging device, wherein the imaging device Shake detection means for detecting shake; Above Correction means for performing a correction operation according to shake information detected by the shake detection means; Above To limit the correction operation of the correction means Corresponds to the cutoff frequency of the band limiting filter Control means for performing a limiting operation by selecting data from table data having at least two or more variables, the control means determines a target reference address according to a correction amount of the correction means, Sequentially change the table data reference address so that it approaches the target reference address And according to the operation status of the imaging device table Change data reference address change amount and change cycle The table data is determined so as to have a predetermined limit strength characteristic according to the table data reference address.
[0064]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0065]
FIG. 1 is a block diagram showing a configuration of an image pickup apparatus according to an embodiment of the present invention. FIG. 1 shows a configuration in which an electronic image stabilization function is mounted on a video camera as the image pickup apparatus.
[0066]
In FIG. 1, the lens group has an inner focus type configuration, and includes a first fixed lens 101, a zoom lens 102, a diaphragm 103, a second fixed lens 104, and a focus lens 105. Light from the lens group is imaged on an image sensor 106 such as a CCD, amplified to an optimum level by an amplifier 107, and then input to a camera signal processing circuit 108 to be converted into a standard television signal.
[0067]
The video camera shown in FIG. 1 has an electronic camera shake correction function, and the image stabilization is turned on / off by detecting the state of the switch 117. The angular velocity sensor 109 (pitch direction) and angular velocity sensor 110 (yaw direction) detect the shake angular velocity of the camera body (imaging device body), amplify them by the amplifiers 111 and 112, respectively, and then the image stabilization control microcomputer (microcomputer) 115 The angular velocity signal taken in by the A / D converter 115a and cut in the DC component by the high pass filter (HPF) 115b is integrated by the integrating circuit 115d to be converted into angular displacement.
[0068]
The focal length correction circuit 115e corrects the deflection angle θ calculated by the integration circuit 115d by the focal length f of the optical system, and calculates a correction signal of f × tan θ. The correction system control unit 115h performs shake correction by moving in a direction opposite to the movement direction due to shake according to a correction signal (corresponding to the amount of pixel movement caused by shake on the image sensor 106) that is an output signal of the focal length correction circuit 115e. I do. Reference numeral 115c denotes a band-limiting high-pass filter (band-limiting HPF), which performs a limiting process according to the normalized correction amount obtained by normalizing the correction signal by the correction amount normalization circuit 115f and the output of the HPF 115b. The control unit 115g controls the band limiting HPF 115c to limit the image stabilization capability during the panning operation. This limiting operation will be described in detail later. As a feature of the present invention, the band limiting filter coefficients (a, b) described in FIG. 17 are stored in the table data storage unit 115i as table data for each cutoff frequency. In addition, the table data is created so as to have predetermined characteristics with respect to changes in the table search reference address. In the limiting operation, the limiting strength is changed by selecting a filter coefficient corresponding to the desired cutoff frequency from this table.
[0069]
Next, the extracted image will be described with reference to FIG. The image area extracted by the electronic image stabilization control is, for example, the area 202 in FIG. FIG. 2A shows an imaging screen of the imaging device 106, and 201 corresponds to the area of the entire imaging screen. Among these, only a part of the area, for example, the area (extraction screen) 202 is extracted, and this area 202 is subjected to display processing and recording processing as a full screen like the area 204 in FIG. The position of the extraction screen 202 is changed so as to correct camera shake, and is performed by changing the position coordinates (V0, H0) in the vertical and horizontal directions indicated by 203 in FIG. The position change range of the position coordinate 203 in FIG. 2A is determined by the horizontal / vertical pixel number difference between the area 201 and the area 202 (hereinafter referred to as surplus pixels). Further, the position coordinates 203 in FIG. 2A are corrected by changing the position coordinates 203 in accordance with the amount and direction of camera shake with reference to the origin in the case where there is no camera shake. To be determined.
[0070]
As a method for extracting the area 202, the image of the area 201 is temporarily stored using a field memory, and the area 204 is enlarged to the size of the area 201 while only the image of the area 202 is read to display the area 204. And a method using a high-density, high-pixel type CCD as the image sensor 106 so that the region 202 satisfies the number of scanning lines necessary for a standard TV signal in advance. Since both the former and the latter require an expensive field memory and a large CCD, a general-purpose PAL CCD (PALCCD) is used for an NTSC camera in this embodiment.
[0071]
Since PALCCD has a high pixel density in the vertical direction, the number of lines to be quickly swept in the vertical scanning direction within the range of the number of extra lines compared to the NTSC standard by a CCD drive circuit such as a timing generator changes according to the angular displacement. By doing so, the position of the cut-out image in the vertical direction can be changed. Also, in the horizontal scanning direction, if the relationship between the write start pixel position and the read start pixel position to the line memory 113 is changed while performing the enlargement process by the aspect ratio in the configuration of the line memory 113 and the memory control circuit 114, The screen position can be changed in the horizontal direction, and an inexpensive shake correction device can be realized.
[0072]
FIG. 1 shows the configuration of such a correction system, and the pixel movement in the vertical scanning direction is performed by extracting a desired scanning region by causing the image stabilization microcomputer 115 to control the CCD drive circuit 116 to perform high-speed sweeping control. The pixel movement in the horizontal scanning direction is performed by the line memory 113 for fetching the video signal processed by the camera signal processing circuit 108 and the memory control circuit 114, and the read position of the stored horizontal scanning image is set according to the shake correction pixel movement amount. The image is enlarged and can be enlarged to match the aspect ratio (the memory read rate can be changed and enlarged by thinning and reading), and the signal is returned to the camera signal processing circuit 108 for color processing and the like. Convert to standard TV signal.
[0073]
The image stabilization control microcomputer 115 also controls the zoom lens 102 and the focus lens 105. The image stabilization control microcomputer 115 sends a drive command to the motor 119 via the motor driver 120 in response to a signal from the rotation operation type zoom switch unit 118 whose resistance value changes due to the pressing pressure, so that the zoom lens 102 moves. Then, the scaling operation is performed. Further, the image stabilization control microcomputer 115 sends a drive command to the motor 121 via the motor driver 122 so that the focus lens 105 is moved and focused so that the focus signal processed by the camera signal processing circuit 108 is maximized. Adjustments are made.
[0074]
Next, the image stabilization control operation of the present invention processed by the image stabilization control microcomputer 115 will be described with reference to FIGS. A first object of the present invention is to realize natural camera shake correction that does not interfere with camera work and captured images by a simple restricting operation control method. As a feature of the present invention, the band limiting filter coefficients (a, b) are used as table data for each cutoff frequency so as to satisfy predetermined characteristics with respect to changes in the reference address for table data search. 115i, and the limiting strength is changed by selecting a filter coefficient corresponding to a desired cutoff frequency from this table during the limiting operation. Although the description of the processing flow overlaps with the processing in the image stabilization control microcomputer 115 in FIG. 1, it is shown as a block diagram in FIG. 1, but is actually processed by a program. The description will be given with reference to FIGS.
[0075]
FIGS. 3 and 4 are flowcharts showing the image stabilization control operation procedure, which shows processing for calculating the angular displacement by integrating the angular velocity signals detected by the angular velocity sensors 109 and 110. This process is a periodic interrupt process executed by the image stabilization control microcomputer 115. In this embodiment, the process is executed at 10 times the field frequency, that is, at a frequency of 600 Hz in the case of NTSC. This frequency corresponds to the sampling frequency of the angular velocity signal and the calculation frequency of the angular displacement. An interrupt activation factor in the image stabilization control microcomputer 115 occurs, for example, every time the counter that is counting up (or down) with a predetermined frequency division of the oscillation clock matches data corresponding to 1/600 sec. In addition, as described with reference to FIG. 1, the angular velocity signal is captured by an A / D converter (not shown) of the image stabilization control microcomputer 115, but in this embodiment, the operation mode of the A / D converter is a scan mode for simplicity. It is assumed that the A / D conversion processing operation is repeated at any time.
[0076]
When the interrupt process is started in FIGS. 3 and 4, first, the influence of the DC component is removed by applying a high-pass filter process to the angular velocity signal A / D sampled in step S301. The next step S302 is a process of limiting the frequency band to the angular velocity signal of the AC component, and is composed of steps S302a to S302h (detailed description of step S302 will be given in the description of FIG. 5). . Actually, the high-pass filter process is the same as that in step S302. The cut-off frequency is a fixed value in step S301, but variable in step S302. By changing the cut-off frequency from a low range to a high range, band limitation is possible. How to control the cut-off frequency in step S302 will be described later in conjunction with the flow of FIG. 5, but during the camera work operation such as panning operation, the cut-off frequency is increased to reduce the vibration suppression capability. In normal shooting, the cutoff frequency is controlled to be reduced to eliminate camera shake. Band limit control is also performed in order to prevent unnaturalness of the screen when it collides with a correction end in an attempt to correct a shake larger than the limit of the correctable range.
[0077]
In step S303, the angular velocity signal band-limited in step S302 is integrated to calculate an angular displacement amount. The amount of angular displacement calculated here corresponds to the deflection angle θ applied to the camera body (imaging device body). In step S304, focal length correction is performed to calculate a correction amount. As described above, the correction amount calculated here is calculated as f × tan θ according to each displacement amount obtained in step S303, that is, the deflection angle θ and the focal length f of the optical system.
[0078]
The next processing from step S305 to step S307 is a routine for determining whether or not the deflection angle has been calculated ten times during one field. That is, “m” that is the RAM of the number parameter is incremented in step S305, and it is determined whether or not “m = 10” in the next step S306, that is, whether or not there are ten interruptions. If there are ten interruptions, “m = 0” is initialized in step S307 for the next field, and the processing operation is terminated.
[0079]
On the other hand, if there is no interruption 10 times in the step S306, the step S307 is skipped and the processing operation is terminated.
[0080]
In steps S301 to S304, vertical shake signal processing is performed with the angular velocity signal in the pitch direction that is the output of the angular velocity sensor 109, and horizontal shake signal processing is performed with the angular velocity in the yaw direction that is the output of the angular velocity sensor 110. It is done with a signal.
[0081]
The process of the flow of FIG. 5 is processed once per field, and the process of the flows of FIGS. 3 and 4 is executed 10 times until the next first time is executed, that is, at the end of the current field. Will be.
[0082]
When processing is started in FIG. 5, first, the process stands by until “m = 0” in step S401. When m is initialized by performing interrupt processing 10 times in the current field, the correction amount calculated in step S304 in FIGS. 3 and 4 is normalized in the next step S402.
[0083]
The pitch normalization correction amount and the yaw normalization correction amount are calculated by the following equations (8) and (9).
[0084]
Pitch normalization correction amount = pitch correction amount / vertical pixel size / vertical surplus pixel number / 2 × 100 (%) (8)
Yaw standardization correction amount = Yaw correction amount / horizontal pixel size / number of horizontal surplus pixels / 2 × 100 (%) (9)
In the present embodiment, a PAL CCD (582V × 752H) is used for the NTSC camera. From this, when the NTSC standard vertical 485 line is cut out, the vertical extraction pixel is 627H from the aspect ratio. Therefore, the surplus pixels are 97V × 125H, and the correction direction is positive or negative depending on the direction of camera shake, so that normalization is performed by ½ of the number of surplus pixels.
[0085]
The next step S403 is a process of calculating a reference address for reading out a limit amount for limiting the correction capability based on the normalized correction amount calculated in step S402, and includes steps S403a to S403e. . Here, the limiting amount is a filter coefficient (a, b) corresponding to the cut-off frequency of the band-limited high-pass filter 115c.
[0086]
First, in step S403a, the target reference address An of the data table in the data table storage unit 115i corresponding to the limited target cutoff frequency corresponding to the normalized correction amount is calculated. This target reference address An is determined by the characteristics shown in FIG.
[0087]
FIG. 6 is a diagram showing the characteristic of the target reference address An with respect to the standardized correction amount. In the figure, the horizontal axis represents the standardized correction amount, and all 1/2 of the surplus pixels that are the maximum correction limit are used. The correction is 100%. The vertical axis is a reference address for searching a data table in the data table storage unit 115i. In the present embodiment, when the correction amount is 30% or more, the reference address changes proportionally. When the correction amount is 100%, 128 is selected as the reference address, and the cutoff frequency at this time is 6 Hz. This is because the camera shake frequency described in the above-described conventional example is mainly 5 Hz or less.
[0088]
The relationship between the reference address An and the cut-off frequency fc is shown in FIG. In the figure, the horizontal axis represents the normalized correction amount, and the vertical axis represents the cutoff frequency. In the figure, the cutoff frequency is set to be larger as the reference address is larger, and the filter coefficient (a, b) corresponding to the frequency is read from the data table in the data table storage unit 115i. The relationship between the reference address and the cut-off frequency is a characteristic in which the cut-off changes as a square function as in the conventional example shown in FIG. 13, and the captured image colliding with the correction end is disturbed due to a large deflection angle. In order to prevent this, the characteristic shown in FIG. 6 is set so that the cut-off becomes steeper as the correction ratio approaches the maximum correction limit.
[0089]
FIG. 8 is a diagram illustrating an example of a data table in the data table storage unit 115i. In the data table storage unit 115i, two variables of filter coefficients a (An) and b (An) are set according to the reference address. Are stored as a data string, and filter coefficients a (An) and b (An) are calculated in advance with respect to a necessary cutoff frequency. The data table shown in FIG. 8 is the multiplication coefficient of the high-pass filter described in FIG. 17, and this configuration is shown in FIG.
[0090]
In FIG. 9, 801 is the input data (Sin), 806 is the data before one sampling (Z ^-1 ), A first multiplication processing circuit 807 for multiplying the filter coefficient a (An). Reference numeral 802 denotes a first addition processing circuit, which is input data (Sin) 801, filter coefficient a (An), and data before sampling (Z in the storage unit 806). ^-1 ) And the multiplication value. Let this output data be c. Reference numeral 808 denotes an inversion processing circuit, which stores data (Z ^-1 ) Is reversed. Reference numeral 803 denotes a second addition processing circuit, which is the data before one sampling (−Z ^-1 ) And add. Reference numeral 804 denotes a second multiplication processing circuit (cZ). ^-1 ) And the filter coefficient b (An). Reference numeral 805 denotes final output data (Sout) of the high-pass filter, which is an output of the second multiplication processing circuit 804. The intermediate data (output data) c is the data (ZZ) one sampling before in the storage unit 806 for the next calculation. ^-1 ). By executing this series of calculations at a predetermined cycle, a high-pass filter is obtained.
[0091]
As shown in FIG. 9, the reference address is determined according to the change in the correction amount accompanying panning, and the filter coefficients a (An) and b (An) are selected from the data table in the data table storage unit 115i according to this. By doing so, it becomes possible to change the cutoff frequency.
[0092]
Returning to FIG. 5 again, in step S403b, it is determined whether or not the target reference address An calculated in step S403a is equal to or greater than the current reference address An. If the target reference address An is greater than or equal to the current reference address An, the process proceeds to step S404 after clearing the “release flag” in step S403e. Here, the release flag is a flag that is set when the panning operation is completed, and the cutoff frequency is not lowered until this flag is set, that is, the reference address An is not decreased, as shown in FIG. 4 is controlled in step S302. This is a process for prohibiting the enhancement of the anti-vibration effect by weakening the restriction strength, and is performed to prevent hunting of the restriction operation.
[0093]
On the other hand, if it is determined in step S403b that the target reference address An is smaller than the current reference address An, it is determined in step S403c whether or not the panning operation has ended, so that the output angular velocity signal of the high-pass filter 115b is predetermined. It is determined whether or not the value is smaller than γ. Since the output signal of the high-pass filter 115b is a signal before band limitation or focal length correction is performed, camera shake can be directly detected regardless of the shooting angle of view, and hunting of the limit operation and responsiveness for each angle of view are possible. It is possible to prevent the difference.
[0094]
The predetermined value γ is determined by measuring in advance the output level of the high-pass filter 115b at the end of the panning operation.
[0095]
If the absolute value of the output of the high-pass filter 115b is greater than or equal to the predetermined value γ in step S403c, it is determined that the panning operation is continuing, and the process proceeds to step S403e, and the absolute value of the output of the high-pass filter 115b is If it is not γ or more, a “release flag” is set in step S403d. Since there is no restriction during normal handheld shooting, the target reference address An and the current reference address An are equivalent in step S403b, and the “release flag” remains in the clear state.
[0096]
In this way, while the shooting state determination during the panning operation is performed, the limiting operation is controlled in step S302 in FIGS. 3 and 4, it is determined whether or not the target reference address An and the current reference address An are equal. If they are equal, the process proceeds to step S302h, and the filter coefficient a (An) having the same cutoff frequency as the current one is obtained. b (An) is read from the table, the coefficient is set again in the band-limited HPF 115c, and the process proceeds to step S303.
[0097]
On the other hand, if the target reference address An is not equal to the current reference address An in step S302a, it is determined in step S302b whether the current reference address An is smaller than the target reference address An. When the current reference address An is smaller than the target reference address An, it is a case where the current reference address An has not reached the target reference address An, and it is determined that the restriction should be strengthened in step S403 in FIG. Is the case. In this case, after the reference address An is increased from the current value by a predetermined value α in step S302g in FIGS. 3 and 4, the process proceeds to step S302h.
[0098]
On the other hand, if the target reference address An is smaller than the current reference address An in the step S302b, it is determined in the next step S302c whether or not the “release flag” is set. If the release flag is clear, the reference address is held at the current value so as not to lower the cutoff frequency, and the process proceeds to step S302h.
[0099]
On the other hand, if the release flag = 1 in step S302c, the panning operation may be terminated and the cut-off frequency may be reduced. Therefore, the number counter C0 is incremented in step S302d, and the number counter C0 is determined in step S302e. It is determined whether or not is an even number. If the number counter C0 is not an even number but an odd number, the process proceeds to step S302h. If the number counter C0 is an even number, the reference address is set to a value smaller than the current value by a predetermined value β in step S302f. The number counter C0 is for delaying the change period of the reference address An compared to the time of starting the panning operation so that the change of the cut-off frequency at the end of the panning operation is reduced. Then, the filter coefficient corresponding to the reference address An reset in step S302h is read, and the setting of the band limiting HPF 115c is updated.
[0100]
While the processing of FIG. 5 is executed in a field cycle, the processing of FIGS. 3 and 4 is performed 10 times per field, and the rate counter C0 has a change rate of predetermined values α and β used in steps S302f and S302g. The increase / decrease of the reference address An is controlled in a cycle in which becomes even. Here, the predetermined value for determining the rate of change is determined so as to have a limited strength change characteristic as shown in FIGS. 10 and 11, for example. 10 and 11, the horizontal axis is time, and the vertical axis is the cutoff frequency.
[0101]
FIG. 10 is a diagram showing a change characteristic of the cut-off frequency at the start of the panning operation (imaging), and shows an example in which the panning operation is started from time 901. At the start of the panning operation, if the target cutoff frequency is not reached with a quick response, there is a possibility that a marginal collision that collides with the correction limit may occur. Further, since the shooting screen is flowing during the panning operation, even if the cut-off frequency is rapidly changed, the screen is not disturbed. Therefore, at the start of the panning operation, the predetermined value α becomes a large value so that the target limit amount is reached in a short time as at the time 902.
[0102]
FIG. 11 shows a case where the panning operation is completed at time 903. After the time 903, since the shooting screen is close to a stationary state, a sudden change in the cut-off frequency becomes a movement on the screen, and when the correction capability is increased immediately after the panning operation is finished, a shakeback occurs. End up. In order to solve these problems, the responsiveness is lowered at the end of the panning operation, and the predetermined value β is determined so that the cut-off frequency changes slowly as shown by the curve 904, and the change period is compared with that at the start of the panning operation. Has doubled.
[0103]
In this embodiment, the change cycle of the reference address at the end of the panning operation is twice as long as that at the start of the panning operation, but is not limited to this. It only has to be set so that there is no.
[0104]
In the present embodiment, a method is used in which both the predetermined values α and β are constants and the reference address changes linearly. With this technique, the cutoff frequency that is the target of the band limitation changes as a result of the characteristics shown in FIG. 7, and the limited target cutoff frequency corresponding to the correction amount and the change locus leading to the target cutoff frequency are the same. Since it can be changed by the characteristic, it does not become a change locus like 1303 in FIG. 15 described above, and it is possible to prevent the screen from being hindered by the change of the cut-off frequency.
[0105]
In addition, the control operation process can be realized by a simple operation of adding and subtracting the reference address, and a system configuration using a cheaper microcomputer can be achieved.
[0106]
Returning to FIG. 5 again, in step S404, the target position coordinates (V0, H0) of the cutout position are calculated based on the correction signal (f × tan θ) calculated in step S303 of FIGS. Here, the target positions VO and VH are calculated by the following equations (10) and (11), and the number of pixels to be moved is obtained by shake correction.
[0107]
V0 = vertical origin position ± number of moving pixels for correcting the deflection angle in the pitch direction
= Vertical origin position ± (−1) × Pitch correction amount / Vertical pixel size (10)
H0 = vertical origin position ± number of moving pixels to correct the deflection angle in the yaw direction
= Vertical origin position ± (−1) × Yaw correction amount / Horizontal pixel size (11)
Next, in step S405, the target position coordinates (V0, H0) calculated in step S404 are set as cutout positions, and a command is output to the CCD drive circuit 116 and the memory control circuit 114, and then the step S401 is used for the next field. Control is performed so as to return to step 10 and wait until the integration process is performed 10 times.
[0108]
As described above, according to the present embodiment, the ROM table has a plurality of band limit data having predetermined characteristics according to the cutoff frequency for performing the limit operation, and the table data reference address is set according to the shake correction amount. By controlling and changing the change amount and change period of the table data reference address according to the camera operation state, it becomes possible to select an inexpensive microcomputer or to perform combined processing with other processing, and at the time of panning operation start It becomes possible to improve the responsiveness of the limiting operation and to prevent the swing-back phenomenon that tends to occur at the end of the panning operation. In addition, it is possible to determine the limit intensity and the limit intensity change rate with the same characteristics, prevent screen movement due to the limit intensity change during panning operation, and realize natural camera work at any shooting angle of view. It becomes possible.
[0109]
In the present embodiment, the configuration using the PAL CCD and the line memory has been described. However, correction may be performed by controlling the extracted image position using the field memory, and enlargement control may be performed. A large or ultra-high pixel type CCD that does not need to be used may be used, or an optical correction means may be used.
[0110]
In this embodiment, the angular velocity sensor is used as the shake detection means. However, the present invention is not limited to this, and an acceleration sensor may be used. In this case, if integration processing is performed once more inside or outside the vibration-proof microcomputer. good.
[0111]
In the present embodiment, the calculation of the deflection angle displacement amount has been described as software processing, but may be configured by hardware.
[0112]
Furthermore, in the present embodiment, the band limitation by the high-pass filter is exemplified as the limiting unit. However, the integration feedback coefficient and gain coefficient in the integration circuit 115d may be converted into table data, and the band limitation may be performed by integration processing.
[0113]
【The invention's effect】
As detailed above, the present invention IMAGING DEVICE AND IMAGING DEVICE CONTROL METHOD According to By performing data selection from table data having at least two or more variables corresponding to the cutoff frequency of the band limiting filter, Multiple data related to bandwidth limitation can be acquired at the same time, and the calculation time for calculating the data can be saved, so an inexpensive microcomputer can be selected even for anti-vibration control that is processed at high speed. And other processing (focus adjustment, exposure adjustment, etc.) can be performed in parallel, and a simple system can be selected.
[0114]
In addition, the present invention IMAGING DEVICE AND IMAGING DEVICE CONTROL METHOD According to the above, by changing the change amount and the change cycle of the data table reference address according to the shooting situation, it is possible to quickly perform the limiting operation at the start of the panning operation and to easily cause the shake back at the end of the panning operation Prevent the phenomenon This It has the effect of being able to.
[0115]
In addition, the present invention IMAGING DEVICE AND IMAGING DEVICE CONTROL METHOD In particular, in the limited operation control, the target value is determined by data selection from the data table having a predetermined characteristic, and the reference address is sequentially determined so as to approach the target value. It is possible to determine the rate with the same characteristics, and it is possible to prevent the movement of the screen due to the change in the limit intensity during the panning operation, and it is possible to realize natural camera work at any shooting angle of view. .
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining an image region extracted by electronic image stabilization control in the imaging apparatus according to the embodiment of the present invention.
FIG. 3 is a flowchart illustrating an image stabilization control operation procedure of the imaging apparatus according to the embodiment of the present invention.
FIG. 4 is a flowchart showing an image stabilization control operation procedure of the imaging apparatus according to the embodiment of the present invention.
FIG. 5 is a flowchart illustrating an image stabilization control operation procedure of the imaging apparatus according to the embodiment of the present invention.
FIG. 6 is a diagram illustrating a relationship between a correction amount and a reference address in the imaging apparatus according to an embodiment of the present invention.
FIG. 7 is a diagram illustrating a relationship between a reference address and a cutoff frequency in the imaging apparatus according to an embodiment of the present invention.
FIG. 8 is a diagram illustrating an example of a data table in a data table storage unit in the imaging apparatus according to an embodiment of the present invention.
FIG. 9 is a block diagram illustrating a configuration of a band limitation processing unit in the imaging apparatus according to an embodiment of the present invention.
FIG. 10 is a diagram illustrating a change characteristic of a cutoff frequency at the start of a panning operation (imaging) in the imaging apparatus according to an embodiment of the present invention.
FIG. 11 is a diagram illustrating a change characteristic of a cutoff frequency at the end of a panning operation (photographing) in the imaging apparatus according to an embodiment of the present invention.
FIG. 12 is a block diagram illustrating a configuration of a conventional imaging device.
FIG. 13 is a flowchart showing a processing operation procedure in a conventional imaging apparatus.
FIG. 14 is a flowchart illustrating a processing operation procedure in a conventional imaging apparatus.
FIG. 15 is a diagram illustrating a relationship between a normalized correction amount and a cutoff frequency in a conventional imaging apparatus.
FIG. 16 is a diagram illustrating a relationship between a focal length and an effective image circle diameter and a relationship between a focal length and a maximum correction range in a conventional imaging apparatus.
FIG. 17 is a block diagram illustrating a configuration of a band limitation processing unit in a conventional imaging apparatus.
[Explanation of symbols]
101 First fixed lens
102 Zoom lens
103 aperture
104 Second fixed lens
105 Focus lens
106 Image sensor
107 amplifier
108 Camera signal processing circuit
109 Angular velocity sensor (pitch direction)
110 Angular velocity sensor (yaw direction)
111 amplifier
112 Amplifier
113 line memory
114 Memory control circuit
115 Anti-vibration control microcomputer
115a A / D converter
115b HPF (High Pass Filter)
115c Band-limited HPF (High Pass Filter)
115d integration circuit
115e Focal length correction circuit
115f Correction amount normalization circuit
115g Limit processing control unit
115h Correction system control unit
115i table data storage unit
116 CCD drive circuit
117 switch
118 Zoom switch unit
119 motor
120 Motor driver
121 motor
122 Motor driver

Claims (4)

A method for controlling an imaging apparatus,
A shake detection step for detecting shake of the imaging device, a correction step for performing a correction operation according to shake information detected by the shake detection step, and a band limiting filter for limiting the correction operation of the correction step . A control step of performing a limiting operation by selecting data from table data having at least two or more variables corresponding to the cutoff frequency ,
The control step determines a target reference address according to the correction amount of the correction step, sequentially changes the table data reference address so as to approach the target reference address, and according to the operation status of the imaging device Change table data reference address change amount and change cycle ,
The control method for an imaging apparatus, wherein the table data is determined so as to have a predetermined limit intensity characteristic according to the table data reference address. 2. The control of an image pickup apparatus according to claim 1, wherein the limit intensity characteristic of the table data is determined so that a change in the limit intensity accompanying a change in the selected data does not affect the shooting screen. Method. An imaging device,
A shake detecting means for detecting a shake of the image pickup apparatus, a correction means for correcting operation in response to the detected vibration information by the shake detection means, the band-limiting filter to add a restriction to the correction operation of said correcting means Control means for performing a limiting operation by selecting data from table data having at least two or more variables corresponding to a cutoff frequency ;
The control means determines a target reference address according to the correction amount of the correction means, sequentially changes the table data reference address so as to approach the target reference address, and changes the table data reference address according to the operation status of the imaging device. Change table data reference address change amount and change cycle ,
The imaging apparatus is characterized in that the table data is determined so as to have a predetermined limit intensity characteristic according to the table data reference address. The imaging apparatus according to claim 3, wherein the limit intensity characteristic of the table data is determined so that a limit intensity change associated with a change in the selected data does not affect the shooting screen.

Images