JP3607857B2 - Endoscope device - Google Patents

Description

この式（１）による処理は、Ｂ画像をある一定の比率でＧに混合し生成されたデータを新たにＧ画像とする変換例である。各バンドの照明光を狭帯域化することで、血管網などの吸収散乱体が深さ位置で異なることをより明確化することが可能となる。
【００３５】
つまり、各バンドが反映する生体補造に関する情報の差を照明光を狭帯域化することで、より拡大することができる、ということである。
【００３６】
これら狭帯域ＲＧＢ画像をカラー画像で観察した場合、例えぱ図１１に示すような画像となる。太い血管が深い位置にあり、Ｒバンド画像に反映され、カラーとしては青色系のパターンとして示される。中層付近にある血管網はＧ画像に強く反映されるので、カラー画像としては赤色系のパターンとして示される。血管網の内、粘膜表面付近に存在するものは黄色系のパターンとして表現される。
【００３７】
とくに、この粘膜表面付近のパターンの変化は、早期病変の発見鑑別診断にとって重要である。しかし、黄色系のパターンは、背景粘膜とのコントラストが弱く、視認性が低いという傾向がある。
【００３８】
そこで、この粘膜表面付近のパターンをより明瞭に再現するために、式（１）に示す変換が有効となる。式（１）は、マトリックス形式で示すと式（２）のようになる。
【００３９】
【数２】

したがって、係数変更回路６４を通じてマトリックス係数を調整することで、ユーザは表示効果を調整することが可能となる。動作としては、電子内視鏡３の操作部に設けられたモード切替スイッチ（図示せず）に連動して画像処理手段内では、スルー動作から、マトリックス係数がデフォルト値に設定される。
【００４０】
ここでいうスルー動作とは、３×３マトリックス回路６１には単位行列、ＬＵＴ６２ａ，６２ｂ，６２ｃ，６３ａ，６３ｂ，６３ｃは非変換テープルを搭載した状態をいう。デフォルト値には、マトリックス係数に、例えばω_Ｇ＝０．２、ω_Ｂ＝０．８という設定値を与えるということである。
【００４１】
そして、ユーザは電子内視鏡３の操作部やビデオプロセッサ筐体パネル等に設けられた処理変更スイッチ等を操作して、この係数をω_Ｇ＝０．４、ω_Ｂ＝０．６などというように調整を行なう。ＬＵＴ６２ａ，６２ｂ，６２ｃ，６３ａ，６３ｂ，６３ｃには、必要に応じて逆γ補正テープル、γ補正テーブルが適用される。
【００４２】
次に、色変換処理回路３０ａにおいて、フィルタが切替えられても、平均色調を極力維持するように色補正を行なう処理について説明する。
【００４３】
フィルタ切替の結果、照明光の分光特性が変化する。その結果として、色再現も変化する。使用状況やユーザによっては、粘膜表面状の微細構造のコントラスト向上などの効果は維持しつつも、平均的な色再現はできるだけ維持したい場合もある。このような場合、フィルタ切替に応じて、スルー動作から平均色調を維持するような色変換動作をさせるように、係数変更回路６４により動作を変更する必要がある。
【００４４】
平均色調を維持するようなマトリックスの作成手順を以下に示す。図１２に示すように、フィルタ切替に応じて、ＲＧＢ色空間における被写体の色分布は第１分布から第２分布に移動するとする。このような場合、第１分布から少なくとも３点選択（通常は、分布平均や重心データを含む）し、これら３点が第２分布でどこに移動するか調べておく。そして第２分布から第１分布への変換マトリックスをこの３組のデータを使用して計算し３×３マトリックス回路６１のマトリックス係数とする。なお、３点以上選択して最小２乗法により決定することもできる。
【００４５】
ＬＵＴ６２ａ，６２ｂ，６２ｃ，６３ａ，６３ｂ，６３ｃには必要に応じて逆γ補正、γ補正テーブルを設定して、上記マトリックス係数を適用すれば、フィルタ切替時にも平均色調は極力維持した色再現を達成することができる。
【００４６】
また、特に狭帯域Ｂ画像がピットパターンなどの粘膜表面微細構造を良く反映することを利用して、Ｂ画像だけで、色素染色のような画像効果を再現することが可能である。すなわち、式（３）に示すマトリックス変換式より入力されたＲＧＢデータの内、Ｂデータのみで出力ＲＧＢデータを構成する。
【００４７】
【数３】

そして係数を調整することで、色素染色画像のような効果を出すことができる。例えば、ω_Ｂ＞＞ω_Ｇ、ω_Ｒに設定すると、画像は青系色調を呈することになり、インディゴ染色を行なった場合と同系色の色調になる。また、ω_Ｂ、ω_Ｒ＞＞ω_Ｒに設定すると、画像は紫系色調を呈することになり、ピオクタニン染色調の画像になる。さらに、ＬＵＴの設定を図１３のように設定すると、コントラストが硬調な再現となり、染色画像に見られるコントラストの高い画像が得られる。
【００４８】
このように本実施の形態によれば、色変換処理回路３０ａのパラメータをフィルタ切替と連動して設定することで、狭帯域ＲＧＢ照明光の深達度情報という特徴を生かした表現方法を実現することが可能となり、生体組織の組織表面近くの所望の深部の組織情報を分離して視認することできる。
【００４９】
なお、上記実施の形態では、３×３マトリックス回路６１を中心とした構成により色変換処理回路３０ａを示したが、図１４に示すように、色変換処理回路３０ａを各バンドに対応した３次元ＬＵＴ７１で置き換えても同様の効果を得ることができる。この場合、係数変更回路６４は、モード切替回路４２からの制御信号に基づいてテーブルの内容を変更する動作を行なう。
【００５０】
図１５ないし図１８は本発明の第２の実施の形態に係わり、図１５は内視鏡装置の構成を示す構成図、図１６は図１５の画像処理回路の構成を示す構成図、図１７は図１５の色調整回路の構成を示す構成図、図１８は図１５の色調整回路でのＬ＊ａ＊ｂ＊色空間上での色相、彩度の概念を示す図である。
【００５１】
第２の実施の形態は、第１の実施の形態とほとんど同じであるので、異なる点のみ説明し、同一の構成には同じ符号をつけ説明は省略する。
【００５２】
本実施の形態では、フィルタ切替の動作と連動して動作を変更する色変換処理回路の色変換として、ＸＹＺなどモニタなどのデバイスに依存しない色空間とＲＧＢなどデバイスに依存する色空間との間の座標変換手段を含む場合を示す。
【００５３】
図１５に示すように、電子内視鏡２には処理切替指示スイッチ８１が設けられ、画像処理回路３０は、モード切替回路４２からの制御信号と処理切替指示スイッチ８１からの指示信号を受け取り、後述する色変換処理を行う。
【００５４】
図１６に示すように、画像処理回路３０に構成される色変換処理回路３０ｂは、各バンド毎に設置されたＬＵＴ８２ａ，８２ｂ，８２ｃと、３×３マトリックス回路８３と、色調整回路８４と、後段の３×３マトリックス回路８５、そしてその後段に位置し各バンド毎に設置されたＬＵＴ８６ａ，８６ｂ，８６ｃと、係数変更回路６４とから構成される。
【００５５】
最初に前段ＬＵＴ８２ａ，８２ｂ，８２に入力されたＲＧＢデータは逆γ補正を施される。これは、ＣＲＴなどの表示デバイスのγ特性を考慮して行われる非線形なγ補正を色変換処理の前にキャンセルするためである。
【００５６】
次に、前段の３×３マトリックス回路８３にて、ＲＧＢからデバイス非依存の色空間であるＸＹＺに変換する。変換式を式（４）に示す。式（４）においてｘｉ、ｙｉ、ｚｉ（ｉ＝Ｒ，Ｇ，Ｂ）はＣＲＴなどの表示デバイスの原色のｘｙ色度座標である。
【００５７】
【数４】

次に、色調整回路８４において後述する適当な色調整を受けたあと、後段の３×３マトリックス回路８５にて式（５）により再度デバイス依存の色空間であるＲ’Ｇ’Ｂ’に変換され、モニタ表示用にγ補正が後段のＬＵＴで行われた後、観察モニタ５に出力される。
【００５８】
【数５】

次に、色調整回路８４の動作を説明する。色調整回路８４は、図１７に示すように、ＸＹＺからＬ＊ａ＊ｂ＊などの知覚色空間への変換を行なう知覚色空間変換部８７と、人間が色の三属性として知覚する色相、彩度への変換、およびこれらの値を調整して直感的に色調整を行なった後、Ｌ＊ａ＊ｂ＊に逆変換を行なう色相、彩度変換調整部８８、そして再度ＸＹＺへの変換を行なう知覚色逆変換部８９とから構成される。
【００５９】
Ｌ＊ａ＊ｂ＊とＸＹＺとの間の変換式を式（６）に示し、さらにＬ＊ａ＊ｂ＊から色相Ｈａｂ、Ｃａｂへの変換式を式（７）に示す。ここで、Ｘｗ，Ｙｗ，Ｚｗは基準白色のＸＹＺ値を表す。
【００６０】
【数６】

【数７】

また、Ｌ＊ａ＊ｂ＊色空間上での色相、彩度の概念を図１８に示す。
【００６１】
いったん、色相、彩度に変換されたなら、色調整は直感的に行なうことができる。例えぱ、色調を鮮やかにしたければ彩度に一定係数を乗算するか、加算して値を上げれぱ良い。また色を青方向、赤方向などに変化させたければ色相の値を調整すれば良い。このようにして、色調整手段において直感的な色調整が可能になる。
【００６２】
次に、モード切替回路４２、および処理切替指示スイッチ８１と連携した動作について説明する。狭帯域ＲＧＢ照明光で観察した場合の特徴は、血管構造など生体の深さ方向に異なる構造を持つ場合に、それらが異なる色で表されるということがある。この特徴をより強調するため、彩度を強調し、色相を適当に回転させることで、より効果的な表示が可能となる。
【００６３】
したがって、モード切替回路４２と連動して、例えば通常観察時には色調整は行なわずにスルーで流し、狭帯域観察時には色調整を行なうように、処理切替指示スイッチ８１からの指示信号に基づいて係数変更回路６４が関連する回路の係数を変更する。さらに、狭帯域ＲＧＢ照明光で観察しているときには、処理切替指示スイッチ８１の指示により彩度の強調度合い、色相の回転度合いをユーザの好み、被写体の種類等に応じて切替える。
【００６４】
なお、ＲＧＢからＸＹＺの変換は、通常のＣＲＴデバイスモデルに基づく式で行なったがＸＹＺのうち輝度Ｙの計算方法に関して式（８）に示すように変更してもよい。式（８）では、Ｙを算出する際に、ＲＧＢの比率を指定できるように変更している。
【００６５】
【数８】

狭帯域ＲＧＢのＢ画像には生体粘膜表面の微細構造が高いコントラストで反映されるという特徴がある。この情報を輝度情報に反映させるためには、Ｙを算出する際のＢの重みω_Ｂを大きくすれぱ良い。一般的にＢの輝度はＲＧに比較して低いため（人間の輝度感度はＧが最大となっている）、そのまま式（６）で計算するとこのＢの情報が輝度に大きくは反映されない。したがって、前記のようにＢの重みを調整する意味が出てくる。
【００６６】
狭帯域ＲＧＢ画像は、各々のバンド画像が、異なった生体構造を反映するため、式（８）により利用目的に応じて、重みを調整することができる。なお、重みの組合せについては予め複数種類用意しておき、処理切替スイッチからの制御で切替えられるようにすれば良い。なお、この場合のＸＹＺからＲＧＢへの逆変換は式（７）を用いる。
【００６７】
このように本実施の形態でも、第１の実施の形態と同様に、色変換処理回路３０ａのパラメータをフィルタ切替と連動して設定することで、狭帯域ＲＧＢ照明光の深達度情報という特徴を生かした表現方法を実現することが可能となり、生体組織の組織表面近くの所望の深部の組織情報を分離して視認することできる。
【００６８】
図１９ないし図２４は本発明の第３の実施の形態に係わり、図１９は内視鏡装置の構成を示す構成図、図２０は図１９の回転フィルタの構成を示す構成図、図２１は図２０の回転フィルタのＧ２、Ｂ２ａ、Ｂ２ｂのフィルタの分光透過特性を示す図、図２２は図１９のバンド選択回路の構成を示す構成図、図２３は図１９の回転フィルタの変形例の構成を示す構成図、図２４は図２３の回転フィルタの分光透過特性を示す図である。
【００６９】
第３の実施の形態は、第１の実施の形態とほとんど同じであるので、異なる点のみ説明し、同一の構成には同じ符号をつけ説明は省略する。
【００７０】
図１９に示すように、本実施の形態では、セレクタ２６の出力として４つの同時化メモリ２７ａ，２７ｂ，２７ｃ，２７ｄと、４つの同時化メモリ２７ａ，２７ｂ，２７ｃ，２７ｄの出力に対して画像処理を行う画像処理回路３０と、画像処理回路３０により処理された４つのデータをアナログデータに変換するＤ／Ａ回路３１ａ，３１ｂ，３１ｃ、３１ｄと、Ｄ／Ａ回路３１ａ，３１ｂ，３１ｃ、３１ｄの出力に対してマトリックス演算を施し３つのバンドデータに出力するバンド選択回路１０１とを有している。
【００７１】
同時化メモリを４つ備えている理由は、２重構造の回転フィルタ１４の第２のフィルタ組が、図２０に示すように、４つの帯域Ｒ２、Ｇ２、Ｂ２ａ、Ｂ２ｂのフィルタから構成され、これらＲ２、Ｇ２、Ｂ２ａ、Ｂ２ｂのフィルタの分光透過特性は図２１に示すようになっている。
【００７２】
そして、モード切替指示スイッチ４１より制御信号がモード切替回路４２の制御信号によって回転フィルタ１４が第２のフィルタ組（Ｒ２、Ｇ２、Ｂ２ａ、Ｂ２ｂ）に指定されると、４つのバンド画像が同時化メモリ２７ａ，２７ｂ，２７ｃ，２７ｄに入力される。４つのバンド画像は、画像処理回路３０において色調整等の処理を受けた後、Ｄ／Ａ回路３１ａ，３１ｂ，３１ｃ、３１ｄでＤ／Ａ変換後、バンド選択回路１０１に入力される。
【００７３】
ユーザは、電子内視鏡３の操作部に設けられたバンド切替指示スイッチ１０２により、４つのバンドのうち、どのバンドを用いて観察モニタ５上に画像を出力するかを指定する。
【００７４】
バンド選択回路１０１は、図２２に示すように、４×３マトリックス回路１０５とマトリックス係数変更回路１０６とから構成され、バンド切替指示スイッチ１０２から出力されたバンド切替指示信号は、バンド選択回路１０１に設けられたマトリックス係数変更回路１０６に入力される。マトリックス係数変更回路１０６は、バンド切替指示信号に基づき所定のマトリックス係数を４×３マトリックス回路１０５に適用する。
【００７５】
式（９）にマトリックス回路の式を示す。
【００７６】
【数９】

式（９）に示すように、バンド選択回路１０１では、４バンド画像の入力値（Ｄ_Ｒ２，Ｄ_Ｇ２，Ｄ_Ｂ２ａ，Ｄ_Ｂ２ｂ）に対して４×３のマトリックス係数を作用させ、３つの出力信号（ｄ_ｒ，ｄ_ｇ，ｄ_ｂ）を得て、この信号を３色信号として観察モニタ５に出力する。
【００７７】
マトリックス係数の例を式（１０）に示す。
【００７８】
【数１０】

Ｍ１で設定した係数は、Ｒ２、Ｇ２、Ｂ２ａにより画像を構成し、Ｍ２はＢ２ａの代わりにＢ２ｂを用いる設定である。Ｍ１とＭ２での切替は、例えば、Ｂ２ａを近紫外光に中心波長を設定し、Ｂ２ｂにはヘモグロビン吸収波長帯（例えば４１５ｎｍ）に設定することで、Ｍ１が適用された場合はピットパターン等の微小凹凸の詳細に観察するモード、Ｍ２が適用された場合は粘膜表面付近の微細な毛細血管網を詳細に観察するモードとして、状況に応じて使い分けることが可能となる。
【００７９】
また、係数Ｍ３は、Ｂ２ａ、Ｂ２ｂの２バンドで画像を構成するので、Ｂ２ａ、Ｂ２ｂとして３８０ｎｍ付近で接近した狭帯域フィルタを構成することで、粘膜表面付近の細胞構造の変化等による散乱特性の変化を捉えるのに好適である。
【００８０】
また、単にあるバンドの単色画像をモノクロ像として観測したければＭ４のように設定すればよいし、各バンドの特性を生かして、複数のバンドを一定の比率で混合して出力するためにＭ５のように係数を設定することもできる。
【００８１】
このように本実施の形態によれば、第１の実施の形態の効果に加え、通常観察から狭帯域フィルタ観察に切替えるためフィルタの変更を行なった際に、画面が極端に暗くなることがなく、十分観察が可能な明るさの照明光量を得ることができる。さらに、複数フィルタの内、どのバンドで画像を観察するか選択することが可能となるので、ユーザは使用状況に応じて最適な観察像を得ることができる。
【００８２】
なお、本実施の形態では回転フィルタを１４を２重構成としているが、画像上の効果を得るのにＢフィルタを変更するだけで良い場合は、回転フィルタを１重構成とすることもでき、図２３に示すように４つのフィルタで回転フィルタ１４を構成する。フィルタ特性は例えぱ、図２４に示すようにＢフィルタのみを狭帯域化する構成がある。これは、この波長帯付近の光の生体への深達度が浅いことを利用して、フィルタの狭帯域化により、より表面付近の血管等の生体構造のコントラストを向上させることが目的となる。このような回転フィルタ１４の構成と取ることで、フィルタ切替を行なわないでも、観察状況に応じて、ユーザはバンド切替の指示だけで、最適な観察像を得ることができる。
【００８３】
【発明の効果】
以上説明したように本発明によれば、生体組織の組織表面近くの所望の深部の組織情報を分離して視認することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係る内視鏡装置の構成を示す構成図
【図２】図１の回転フィルタの構成を示す構成図
【図３】図２の回転フィルタの第１のフィルタ組の分光特性を示す図
【図４】図２の回転フィルタの第２のフィルタ組の分光特性を示す図
【図５】図１の内視鏡装置により観察する生体組織の層方向構造を示す図
【図６】図１の内視鏡装置からの照明光の生体組織の層方向への到達状態を説明する図
【図７】図３の第１のフィルタ組を透過した面順次光による各バンド画像を示す図
【図８】図４の第２のフィルタ組を透過した面順次光による各バンド画像を示す図
【図９】図１の調光回路による調光制御を説明する図
【図１０】図１の画像処理回路の構成を示す構成図
【図１１】図１０の画像処理回路により得られた狭帯域ＲＧＢ画像をカラー画像を示す図
【図１２】図１０の３×３のマトリックス回路での平均色調を維持するようなマトリックスの作成を説明する図
【図１３】図１０のＬＵＴの設定の一例を示す図
【図１４】図１０の色変換処理回路の変形例の構成を示す構成図
【図１５】本発明の第２の実施の形態に係る内視鏡装置の構成を示す構成図
【図１６】図１５の画像処理回路の構成を示す構成図
【図１７】図１５の色調整回路の構成を示す構成図
【図１８】図１５の色調整回路でのＬ＊ａ＊ｂ＊色空間上での色相、彩度の概念を示す図
【図１９】本発明の第３の実施の形態に係る内視鏡装置の構成を示す構成図
【図２０】図１９の回転フィルタの構成を示す構成図
【図２１】図２０の回転フィルタのＧ２、Ｂ２ａ、Ｂ２ｂのフィルタの分光透過特性を示す図
【図２２】図１９のバンド選択回路の構成を示す構成図
【図２３】図１９の回転フィルタの変形例の構成を示す構成図
【図２４】図２３の回転フィルタの分光透過特性を示す図
【符号の説明】
１…内視鏡装置
２…ＣＣＤ
３…電子内視鏡
４…光源装置
５…観察モニタ
６…画像ファイリング装置
７…ビデオプロセッサ
１０…電源部
１１…キセノンランプ
１２…熱線カットフィルタ
１３…絞り装置
１４…回転フィルタ
１５…ライトガイド
１６…集光レンズ
１７…制御回路
１８…回転フィルタモータ
１９…モード切替モータ１９
２０…ＣＣＤ駆動回路
２１…対物光学系
２２…アンプ
２３…プロセス回路
２４…Ａ／Ｄ変換器
２５…ホワイトバランス回路
２６…セレクタ
２７、２８，２９…同時化メモリ
３０…画像処理回路
３０ａ…色変換処理回路
３１，３２，３３…Ｄ／Ａ回路
３４…符号化回路
３５…タイミングジェネレータ
４１…モード切替スイッチ
４２…モード切替回路
４３…調光回路
４４…調光制御パラメータ切替回路
６１…３×３マトリックス回路
６２ａ，６２ｂ，６２ｃ，６３ａ，６３ｂ，６３ｃＬＵＴ…
６４…係数変更回路[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an endoscope apparatus that captures an image of a living tissue and performs signal processing.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, endoscope apparatuses that irradiate illumination light and obtain an endoscopic image in a body cavity have been widely used. In this type of endoscope apparatus, an electronic endoscope having an image pickup unit that guides illumination light from a light source device into a body cavity using a light guide or the like and picks up an image of a subject using the return light is used. By processing the image signal from the image pickup means, an endoscopic image is displayed on the observation monitor and an observation site such as an affected part is observed.
[0003]
When performing normal biological tissue observation in an endoscopic device, the light source device emits white light in the visible light region, and irradiates the subject with surface sequential light through a rotating filter such as RGB, for example. A color image is obtained by synchronizing and processing the return light from the light with a video processor, or a color chip is arranged in front of the imaging surface of the imaging means of the endoscope, and the return light from the white light is converted to RGB by the color chip. Color images are obtained by picking up images by separation and processing the images with a video processor.
[0004]
On the other hand, in living tissue, the light absorption characteristics and scattering characteristics differ depending on the wavelength of the irradiated light. Therefore, in recent years, it is possible to observe a deep tissue in the living tissue by irradiating the living tissue with infrared light as illumination light, for example. Various infrared endoscope apparatuses have been proposed.
[0005]
[Problems to be solved by the invention]
However, in the diagnosis of a living tissue, deep tissue information near the tissue surface is also an important observation target, but the above-described infrared endoscope apparatus can obtain only deep tissue information deeper than the tissue surface.
[0006]
In addition, when white light is irradiated as RGB surface sequential light by a rotary filter onto a living tissue, the wavelength range thereof is different, so that the imaging signals of each color light have different deep tissue information near the tissue surface of the living tissue. However, in general, in order to make the endoscopic image based on the RGB surface sequential light a more natural color image, the white light is separated into RGB light in which the respective wavelength ranges overlap.
[0007]
That is, in the overlapped RGB light, a wide range of deep tissue information is captured in the light imaging signal of each wavelength region, and thus it is difficult to visually recognize desired deep tissue information near the tissue surface of the living tissue. There's a problem.
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an endoscope apparatus capable of separating and visually recognizing desired deep tissue information near the tissue surface of a living tissue.
[0009]
[Means for Solving the Problems]
An endoscope apparatus according to the present invention includes an illumination light supply unit that supplies illumination light including a visible light region, and an endoscope that includes an imaging unit that irradiates the subject with the illumination light and captures the subject with return light. In an endoscope apparatus comprising signal processing means for performing signal processing on an imaging signal from the imaging means, A plurality of wavelength regions of the illumination light, arranged in an optical path from the illumination light supply unit to the imaging unit, and distributed according to the depth of light with respect to the subject. A band limiting unit that limits the band of at least one wavelength region to narrow the band image of the discrete spectral distribution of the subject on the imaging unit, and the signal processing unit includes: According to the arrangement state, a predetermined color conversion process is performed on the imaging signal whose band is narrowed by the band limiting unit in the wavelength region allocated according to the depth of light with respect to the subject. Do .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0011]
1 to 14 relate to the first embodiment of the present invention, FIG. 1 is a configuration diagram showing the configuration of the endoscope apparatus, FIG. 2 is a configuration diagram showing the configuration of the rotary filter of FIG. 1, and FIG. 2 is a diagram showing the spectral characteristics of the first filter set of the rotary filter of FIG. 2, FIG. 4 is a diagram showing the spectral characteristics of the second filter set of the rotary filter of FIG. 2, and FIG. FIG. 6 is a diagram illustrating a layer direction structure of a living tissue to be observed, FIG. 6 is a diagram illustrating a state in which illumination light from the endoscope apparatus of FIG. 1 reaches the layer direction of the living tissue, and FIG. 7 is a first diagram of FIG. FIG. 8 is a diagram showing each band image by the surface sequential light transmitted through the filter set, FIG. 8 is a diagram showing each band image by the surface sequential light transmitted through the second filter set in FIG. 4, and FIG. 9 is a dimming circuit of FIG. FIG. 10 is a block diagram illustrating the configuration of the image processing circuit of FIG. 1, and FIG. 11 is a diagram illustrating the image processing of FIG. FIG. 12 is a diagram illustrating the creation of a matrix that maintains the average color tone in the 3 × 3 matrix circuit of FIG. 10, and FIG. 13 is a diagram illustrating FIG. FIG. 14 is a diagram showing an example of setting of the LUT, and FIG. 14 is a block diagram showing a configuration of a modification of the color conversion processing circuit of FIG.
[0012]
As shown in FIG. 1, an endoscope apparatus 1 according to the present embodiment includes an electronic endoscope 3 having a CCD 2 as an imaging unit that is inserted into a body cavity and images tissue in the body cavity, and illuminates the electronic endoscope 3. Signal processing is performed on the image pickup signal from the light source device 4 that supplies light and the CCD 2 of the electronic endoscope 3 to display an endoscopic image on the observation monitor 5, or the endoscopic image is encoded and image filing as a compressed image. And a video processor 7 for outputting to the apparatus 6.
[0013]
The light source device 4 includes a xenon lamp 11 that emits illumination light, a heat ray cut filter 12 that blocks heat rays of white light, a diaphragm device 13 that controls the amount of white light that passes through the heat ray cut filter 12, and illumination light. A rotation filter 14 for converting the surface sequential light, a condensing lens 16 for condensing the surface sequential light via the rotation filter 14 on the incident surface of the light guide 15 disposed in the electronic endoscope 3, and the rotation filter 14. And a control circuit 17 for controlling the rotation of the motor.
[0014]
As shown in FIG. 2, the rotary filter 14 has a disk structure and a double structure with the center as a rotation axis, and the outer diameter portion is suitable for natural color reproduction as shown in FIG. An R1 filter 14r1, a G1 filter 14g1, and a B1 filter 14b1 constituting a first filter group for outputting overlapping surface-sequential light with spectral characteristics are arranged, and a desired inner diameter portion as shown in FIG. An R2 filter 14r2, a G2 filter 14g2, and a B2 filter 14b2 constituting a second filter set for outputting narrow-band surface-sequential light having discrete spectral characteristics from which the deep tissue information can be extracted are arranged. As shown in FIG. 1, the rotary filter 14 is rotated by the drive control of the rotary filter motor 18 by the control circuit 17, and is rotated in the radial direction (the movement perpendicular to the optical path of the rotary filter 14 is rotated. The first filter group or the second filter group of the filter 14 is selectively moved on the optical path) by the mode switching motor 19 by a control signal from the mode switching circuit 42 in the video processor 7 described later.
[0015]
The xenon lamp 11, the diaphragm device 13, the rotary filter motor 18 and the mode switching motor 19 are supplied with power from the power supply unit 10.
[0016]
Returning to FIG. 1, the video processor 7 includes a CCD drive circuit 20 that drives the CCD 2, an amplifier 22 that amplifies an imaging signal obtained by imaging the tissue in the body cavity by the CCD 2 via the objective optical system 21, and imaging via the amplifier 22. From a process circuit 23 that performs correlated double sampling and noise removal on a signal, an A / D converter 24 that converts an imaging signal that has passed through the process circuit 23 into image data of a digital signal, and an A / D converter 24 A white balance circuit 25 that performs white balance processing on the image data, a selector 26 and synchronization memories 27a, 27b, and 27c for synchronizing the frame sequential light from the rotation filter 14, and the synchronization memories 27a, 27b, and 27c. Image processing times for reading out each stored image data of frame sequential light and performing gamma correction processing, contour enhancement processing, color processing, etc. 30, D / A circuits 31a, 31b, 31c for converting image data from the image processing circuit 30 into analog signals, an encoding circuit 34 for encoding the outputs of the D / A circuits 31a, 31b, 31c, and a light source The apparatus includes a timing generator 35 that receives a synchronization signal synchronized with the rotation of the rotary filter 14 from the control circuit 17 of the apparatus 4 and outputs various timing signals to the circuits.
[0017]
Further, the electronic endoscope 2 is provided with a mode change switch 41, and an output of the mode change switch 41 is output to a mode change circuit 42 in the video processor 7. The mode switching circuit 42 of the video processor 7 outputs a control signal to the dimming circuit 43, the dimming control parameter switching circuit 44, and the mode switching motor 19 of the light source device 4. The dimming control parameter switching circuit 44 outputs a dimming control parameter corresponding to the first filter group or the second filter group of the rotary filter 14 to the dimming circuit 43, and the dimming circuit 43 is output from the mode switching circuit 42. Based on the control signal and the dimming control parameter from the dimming control parameter switching circuit 44, the diaphragm device 13 of the light source device 4 is controlled to perform appropriate brightness control.
[0018]
As shown in FIG. 5, the body cavity tissue 51 often has an absorber distribution structure such as blood vessels that differ in the depth direction. A large number of capillaries 52 are mainly distributed near the surface of the mucous membrane, and blood vessels 53 that are thicker than the capillaries are distributed in the middle layer deeper than this layer, and thicker blood vessels 54 are further distributed in the deep layers. become.
[0019]
On the other hand, the depth of light in the depth direction with respect to the tissue 51 in the body cavity depends on the wavelength of the light, and the illumination light including the visible range is blue (B) as shown in FIG. In the case of light with such a short wavelength, the light reaches the surface layer only due to the absorption and scattering characteristics in the living tissue, and the light emitted from the surface is observed by being absorbed and scattered in the depth range up to that. Is done. In the case of green (G) light, which has a wavelength longer than that of blue (B) light, it reaches deeper than the range where blue (B) light deepens, absorbs and scatters within that range, and exits from the surface. Light is observed. Still further, red (R) light having a longer wavelength than green (G) light reaches a deeper range.
[0020]
During normal observation, the mode switching circuit in the video processor 7 is controlled by a control signal so that it is positioned on the R1 filter 14r1, G1 filter 14g1, and B1 filter 14b1 as the first filter set of the rotary filter 14 on the optical path of the illumination light. The mode switching motor 19 is controlled.
[0021]
The R1 filter 14r1, the G1 filter 14g1, and the B1 filter 14b during normal observation of the tissue 51 in the body cavity are imaged by the CCD 4 by the B1 filter 14b1 so that the respective wavelength regions overlap as shown in FIG. In FIG. 7A, a band image having a shallow layer and medium layer tissue information including a lot of tissue information in the shallow layer as shown in FIG. 7A is captured, and an image signal captured by the CCD 4 by the G1 filter 14g1 is illustrated in FIG. As shown in FIG. 7 (c), a band image having a shallow layer and medium layer tissue information including a lot of tissue information in the middle layer as shown in FIG. 7 (b) is picked up, and an image signal picked up by the CCD 4 by the R1 filter 14r1 is shown in FIG. A band image having middle layer and deep layer tissue information including a lot of deep tissue information as shown is captured.
[0022]
Then, the video processor 7 synchronizes these RGB image signals and performs signal processing, so that an endoscopic image having a desired or natural color reproduction can be obtained as an endoscopic image.
[0023]
On the other hand, when the mode switching switch 41 of the electronic endoscope 3 is pressed, the signal is input to the mode switching circuit 42 of the video processor 7. The mode switching circuit 42 outputs a control signal to the mode switching motor 19 of the light source device 4, thereby moving the first filter set of the rotary filter 14 that was on the optical path during normal observation to light the second filter set. The rotary filter 14 is driven with respect to the optical path so as to be disposed on the path.
[0024]
The R2 filter 14r2, the G2 filter 14g2, and the B2 filter 14b2 at the time of narrow band light observation of the tissue 51 in the body cavity by the second filter set have a narrow band surface with discrete spectral characteristics as shown in FIG. In order to obtain sequential light, a band image having tissue information in a shallow layer as shown in FIG. 8A is captured in the imaging signal captured by the CCD 4 by the B2 filter 14b2, and the CCD 4 by the G2 filter 14g2 A band image having tissue information in the middle layer as shown in FIG. 8B is picked up in the image pickup signal picked up in FIG. 8B. Further, in the image pickup signal picked up by the CCD 4 by the R2 filter 14r2, FIG. A band image having tissue information in the deep layer as shown is taken.
[0025]
At this time, as apparent from FIG. 3 and FIG. 4, the transmitted light amount by the second filter set is decreased with respect to the transmitted light amount by the first filter set, because the band is narrowed. The circuit 44 outputs a dimming control parameter corresponding to the first filter group or the second filter group of the rotary filter 14 to the dimming circuit 43, so that the dimming circuit 43 controls the diaphragm device 13. As shown in FIG. 9, for example, a linear aperture control line 61 by the aperture device 13 at the time of normal observation according to a setting value Lx on a setting panel (not shown) of the video processor 7 is compared with an aperture device 13 at the time of narrow-band light observation. And the light amount Mx is controlled by the aperture control curve 62 corresponding to the set value Lx. This makes it possible to obtain image data with sufficient brightness even during narrowband light observation.
[0026]
Specifically, in conjunction with the change from the first filter set to the second filter set, the aperture level value corresponding to the light amount setting value Lx is changed from Mx1 to Mx2 as shown in FIG. As a result, the aperture is controlled in the opening direction, and the filter operates to compensate for a decrease in the amount of illumination light due to the narrowing of the band.
[0027]
As shown in FIG. 10, the image processing circuit 30 includes three sets of LUTs 62a, 62b, 62c, 63a, 63b, and 63c and LUTs 62a, 62b, 62c, and 63a on the front and rear sides of the 3 × 3 matrix circuit 61, respectively. , 63b, 63c and a coefficient changing circuit 64 for converting the coefficients of the 3 × 3 matrix circuit 61 to constitute a color conversion processing circuit 30a.
[0028]
The RGB data input to the color conversion processing circuit 30a is converted by the LUTs 62a, 62b, and 62c for each band data. Here, inverse γ correction, nonlinear contrast conversion, and the like are performed.
[0029]
Next, after color conversion is performed in the 3 × 3 matrix circuit 61, γ correction and appropriate gradation conversion processing are performed in the subsequent LUTs 63a, 63b, and 63c.
[0030]
The LUTs 62a, 62b, 62c, 63a, 63b, and 63c can be changed by the coefficient changing circuit 64 that converts the table data and the coefficients of the 3 × 3 matrix circuit 61.
[0031]
The change by the coefficient changing circuit 64 is based on a control signal from the mode switching circuit 42 or a control signal from a processing conversion switch (not shown) provided in the operation unit of the electronic endoscope 3 or the like.
[0032]
Upon receipt of these control signals, the coefficient changing circuit 63 calls appropriate data from the coefficient data previously written in the image processing circuit 30, and rewrites the current circuit coefficient with this data.
[0033]
Next, specific color conversion processing contents will be described. An example of a color conversion formula is shown in Formula (1).
[0034]
[Expression 1]

The processing according to the expression (1) is a conversion example in which B data is mixed with G at a certain ratio and data generated is newly set as a G image. By narrowing the illumination light of each band, it becomes possible to further clarify that absorption scatterers such as a vascular network are different in depth positions.
[0035]
In other words, it is possible to further widen the difference in information relating to bioartificial reflection reflected by each band by narrowing the illumination light.
[0036]
When these narrow-band RGB images are observed as color images, for example, an image as shown in FIG. 11 is obtained. A thick blood vessel is in a deep position, reflected in the R-band image, and shown as a blue pattern as a color. Since the vascular network in the vicinity of the middle layer is strongly reflected in the G image, the color image is shown as a red pattern. Those existing in the vicinity of the mucosal surface in the vascular network are expressed as a yellowish pattern.
[0037]
In particular, this pattern change near the mucosal surface is important for early differential detection and diagnosis of lesions. However, yellow patterns tend to have low contrast with the background mucosa and low visibility.
[0038]
Therefore, in order to reproduce the pattern near the mucosal surface more clearly, the conversion shown in Expression (1) is effective. Expression (1) is expressed in the form of matrix (2).
[0039]
[Expression 2]

Therefore, by adjusting the matrix coefficient through the coefficient changing circuit 64, the user can adjust the display effect. As the operation, the matrix coefficient is set to the default value from the through operation in the image processing means in conjunction with a mode change switch (not shown) provided in the operation unit of the electronic endoscope 3.
[0040]
The through operation here refers to a state in which the 3 × 3 matrix circuit 61 is mounted with a unit matrix, and the LUTs 62a, 62b, 62c, 63a, 63b, and 63c are mounted with non-conversion tables. Default values include matrix coefficients, for example ω _G = 0.2, ω _B That is, a setting value of 0.8 is given.
[0041]
Then, the user operates a process change switch or the like provided on the operation unit of the electronic endoscope 3 or the video processor housing panel, and sets this coefficient to ω. _G = 0.4, ω _B Adjustment is made such as = 0.6. A reverse γ correction table and a γ correction table are applied to the LUTs 62a, 62b, 62c, 63a, 63b, and 63c as necessary.
[0042]
Next, a description will be given of a process of performing color correction so as to maintain the average color tone as much as possible even when the filter is switched in the color conversion processing circuit 30a.
[0043]
As a result of filter switching, the spectral characteristics of the illumination light change. As a result, color reproduction also changes. Depending on the use situation and the user, while maintaining the effect of improving the contrast of the fine structure on the surface of the mucosa, it may be desirable to maintain the average color reproduction as much as possible. In such a case, it is necessary to change the operation by the coefficient changing circuit 64 so as to perform a color conversion operation that maintains the average color tone from the through operation according to the filter switching.
[0044]
A procedure for creating a matrix that maintains the average color tone is shown below. As shown in FIG. 12, it is assumed that the color distribution of the subject in the RGB color space moves from the first distribution to the second distribution in accordance with the filter switching. In such a case, at least three points are selected from the first distribution (usually including distribution average and centroid data), and it is examined where these three points move in the second distribution. Then, a conversion matrix from the second distribution to the first distribution is calculated using these three sets of data, and the matrix coefficient of the 3 × 3 matrix circuit 61 is obtained. Note that three or more points can be selected and determined by the least square method.
[0045]
If the inverse γ correction and γ correction tables are set in the LUTs 62a, 62b, 62c, 63a, 63b, and 63c as necessary, and the matrix coefficients are applied, color reproduction with the average color tone maintained as much as possible even when the filter is switched. Can be achieved.
[0046]
In addition, it is possible to reproduce an image effect such as dye staining only with the B image by utilizing that the narrow band B image reflects the fine structure of the mucosal surface such as a pit pattern. That is, output RGB data is composed of only B data among the RGB data input from the matrix conversion equation shown in Equation (3).
[0047]
[Equation 3]

By adjusting the coefficient, an effect like a dye-stained image can be produced. For example, ω _B >> ω _G , Ω _R When set to, the image has a blue color tone, and has a color tone similar to that in the case of indigo dyeing. Also, ω _B , Ω _R >> ω _R If set to, the image will have a purple color tone and will be a picotanine-stained image. Further, when the LUT is set as shown in FIG. 13, the contrast is reproduced with a high contrast, and an image having a high contrast seen in the stained image is obtained.
[0048]
As described above, according to the present embodiment, by setting the parameters of the color conversion processing circuit 30a in conjunction with the filter switching, an expression method that takes advantage of the feature of the depth information of the narrowband RGB illumination light is realized. This makes it possible to separate and visually recognize desired deep tissue information near the tissue surface of the living tissue.
[0049]
In the above embodiment, the color conversion processing circuit 30a is shown with a configuration centered on the 3 × 3 matrix circuit 61. However, as shown in FIG. 14, the color conversion processing circuit 30a is three-dimensionally corresponding to each band. The same effect can be obtained even if the LUT 71 is used. In this case, the coefficient changing circuit 64 performs an operation of changing the contents of the table based on the control signal from the mode switching circuit 42.
[0050]
FIGS. 15 to 18 relate to the second embodiment of the present invention, FIG. 15 is a block diagram showing the configuration of the endoscope apparatus, FIG. 16 is a block diagram showing the configuration of the image processing circuit of FIG. Is a block diagram showing the configuration of the color adjustment circuit of FIG. 15, and FIG. 18 is a diagram showing the concept of hue and saturation on the L * a * b * color space in the color adjustment circuit of FIG.
[0051]
Since the second embodiment is almost the same as the first embodiment, only different points will be described, and the same components are denoted by the same reference numerals and description thereof will be omitted.
[0052]
In this embodiment, the color conversion of the color conversion processing circuit that changes the operation in conjunction with the filter switching operation is performed between a color space that does not depend on a device such as XYZ and a color space that depends on a device such as RGB. The case where the coordinate conversion means is included is shown.
[0053]
As shown in FIG. 15, the electronic endoscope 2 is provided with a process switching instruction switch 81, and the image processing circuit 30 receives a control signal from the mode switching circuit 42 and an instruction signal from the process switching instruction switch 81, A color conversion process described later is performed.
[0054]
As shown in FIG. 16, the color conversion processing circuit 30b configured in the image processing circuit 30 includes LUTs 82a, 82b and 82c installed for each band, a 3 × 3 matrix circuit 83, a color adjustment circuit 84, The 3 × 3 matrix circuit 85 in the subsequent stage, the LUTs 86a, 86b, and 86c that are located in the subsequent stage and are installed for each band, and the coefficient changing circuit 64 are configured.
[0055]
The RGB data first input to the preceding LUTs 82a, 82b, 82 is subjected to inverse γ correction. This is because nonlinear γ correction performed in consideration of γ characteristics of a display device such as a CRT is canceled before color conversion processing.
[0056]
Next, the previous 3 × 3 matrix circuit 83 converts RGB into XYZ, which is a device-independent color space. The conversion formula is shown in Formula (4). In Expression (4), xi, yi, zi (i = R, G, B) are xy chromaticity coordinates of primary colors of a display device such as a CRT.
[0057]
[Expression 4]

Next, after appropriate color adjustment described later in the color adjustment circuit 84, it is converted again into R′G′B ′, which is a device-dependent color space, by the expression (5) in the subsequent 3 × 3 matrix circuit 85. Then, the γ correction is performed for the monitor display in the LUT in the subsequent stage, and then output to the observation monitor 5.
[0058]
[Equation 5]

Next, the operation of the color adjustment circuit 84 will be described. As shown in FIG. 17, the color adjustment circuit 84 includes a perceptual color space conversion unit 87 that performs conversion from XYZ to a perceptual color space such as L * a * b *, and a hue that humans perceive as three color attributes. After conversion to saturation, and adjusting these values to make intuitive color adjustments, hue that performs inverse conversion to L * a * b *, saturation conversion adjustment unit 88, and conversion to XYZ again And a perceptual color inverse conversion unit 89 for performing the above.
[0059]
A conversion formula between L * a * b * and XYZ is shown in Formula (6), and a conversion formula from L * a * b * to hue Hab and Cab is shown in Formula (7). Here, Xw, Yw, and Zw represent XYZ values of reference white.
[0060]
[Formula 6]

[Expression 7]

FIG. 18 shows the concept of hue and saturation on the L * a * b * color space.
[0061]
Once converted to hue and saturation, color adjustment can be done intuitively. For example, if you want to make the color tone vivid, you can multiply the saturation by a certain coefficient or add it to increase the value. If the color is to be changed in the blue or red direction, the hue value may be adjusted. In this way, the color adjustment means can perform intuitive color adjustment.
[0062]
Next, the operation in cooperation with the mode switching circuit 42 and the process switching instruction switch 81 will be described. The characteristics when observed with narrow-band RGB illumination light are that, when they have different structures such as blood vessel structures in the depth direction of the living body, they are expressed in different colors. In order to further emphasize this feature, more effective display is possible by enhancing the saturation and appropriately rotating the hue.
[0063]
Accordingly, in conjunction with the mode switching circuit 42, for example, the coefficient is changed based on the instruction signal from the processing switching instruction switch 81 so that the color adjustment is not performed during normal observation and the color adjustment is performed during narrow observation and the color adjustment is performed during narrow band observation. Circuit 64 changes the coefficient of the associated circuit. Furthermore, when observing with narrow-band RGB illumination light, the degree of saturation enhancement and the degree of hue rotation are switched according to the user's preference, the type of subject, and the like by an instruction from the processing switching instruction switch 81.
[0064]
Note that the conversion from RGB to XYZ is performed using an expression based on a normal CRT device model, but the calculation method of the luminance Y of XYZ may be changed as shown in Expression (8). In the equation (8), when Y is calculated, the ratio of RGB is changed.
[0065]
[Equation 8]

The narrow band RGB B image has a feature that the fine structure of the surface of the biological mucosa is reflected with high contrast. In order to reflect this information in the luminance information, the B weight ω in calculating Y _B The bigger the better. Since the brightness of B is generally lower than that of RG (G is the maximum for human brightness sensitivity), the information of B is not largely reflected in the brightness when calculated directly using equation (6). Therefore, it makes sense to adjust the weight of B as described above.
[0066]
In the narrow-band RGB image, each band image reflects a different anatomy, and therefore, the weight can be adjusted according to the purpose of use according to Equation (8). A plurality of combinations of weights may be prepared in advance and switched by control from the process selector switch. In this case, the inverse transformation from XYZ to RGB uses equation (7).
[0067]
As described above, in this embodiment as well, in the same way as in the first embodiment, the parameters of the color conversion processing circuit 30a are set in conjunction with the filter switching so that the depth information of the narrowband RGB illumination light is featured. It is possible to realize an expression method that makes use of the above, and it is possible to separate and visually recognize tissue information of a desired deep part near the tissue surface of the living tissue.
[0068]
FIGS. 19 to 24 relate to the third embodiment of the present invention, FIG. 19 is a configuration diagram showing the configuration of the endoscope apparatus, FIG. 20 is a configuration diagram showing the configuration of the rotary filter of FIG. 19, and FIG. 20 is a diagram showing spectral transmission characteristics of the G2, B2a, and B2b filters of the rotary filter of FIG. 20, FIG. 22 is a configuration diagram showing the configuration of the band selection circuit of FIG. 19, and FIG. 23 is a configuration of a modification of the rotary filter of FIG. FIG. 24 is a diagram showing the spectral transmission characteristics of the rotary filter of FIG.
[0069]
Since the third embodiment is almost the same as the first embodiment, only different points will be described, and the same components are denoted by the same reference numerals and description thereof will be omitted.
[0070]
As shown in FIG. 19, in the present embodiment, as the output of the selector 26, an image is output with respect to the outputs of the four synchronization memories 27a, 27b, 27c, 27d and the four synchronization memories 27a, 27b, 27c, 27d. An image processing circuit 30 that performs processing, D / A circuits 31a, 31b, 31c, and 31d that convert four data processed by the image processing circuit 30 into analog data, and D / A circuits 31a, 31b, 31c, and 31d And a band selection circuit 101 that performs a matrix operation on the output and outputs three band data.
[0071]
The reason for having four synchronization memories is that the second filter set of the double-structured rotary filter 14 is composed of filters of four bands R2, G2, B2a, and B2b, as shown in FIG. The spectral transmission characteristics of these R2, G2, B2a, and B2b filters are as shown in FIG.
[0072]
When the rotation filter 14 is designated as the second filter set (R2, G2, B2a, B2b) by the control signal from the mode switching instruction switch 41 by the control signal from the mode switching circuit 42, the four band images are synchronized. The data is input to the memories 27a, 27b, 27c, and 27d. The four band images are subjected to processing such as color adjustment in the image processing circuit 30, are D / A converted by the D / A circuits 31 a, 31 b, 31 c, and 31 d and then input to the band selection circuit 101.
[0073]
The user designates which of the four bands is used to output an image on the observation monitor 5 by using the band switching instruction switch 102 provided in the operation unit of the electronic endoscope 3.
[0074]
As shown in FIG. 22, the band selection circuit 101 includes a 4 × 3 matrix circuit 105 and a matrix coefficient change circuit 106, and the band switching instruction signal output from the band switching instruction switch 102 is sent to the band selection circuit 101. This is input to the provided matrix coefficient changing circuit 106. The matrix coefficient changing circuit 106 applies a predetermined matrix coefficient to the 4 × 3 matrix circuit 105 based on the band switching instruction signal.
[0075]
Equation (9) shows the equation of the matrix circuit.
[0076]
[Equation 9]

As shown in Expression (9), the band selection circuit 101 inputs the input value (D _R2 , D _G2 , D _B2a , D _B2b 4 × 3 matrix coefficients are applied to the three output signals (d) _r , D _g , D _b And this signal is output to the observation monitor 5 as a three-color signal.
[0077]
An example of the matrix coefficient is shown in Expression (10).
[0078]
[Expression 10]

The coefficient set in M1 configures an image with R2, G2, and B2a, and M2 is a setting that uses B2b instead of B2a. Switching between M1 and M2, for example, by setting B2a to a near-ultraviolet light center wavelength and B2b to a hemoglobin absorption wavelength band (for example, 415 nm), when M1 is applied, such as a pit pattern When M2 is applied, a mode for observing the fine irregularities in detail, or a mode for observing the fine capillary network near the mucosal surface in detail, can be used depending on the situation.
[0079]
In addition, since the coefficient M3 constitutes an image with two bands B2a and B2b, a narrow band filter close to 380 nm is formed as B2a and B2b, so that the scattering characteristics due to changes in the cell structure near the mucosal surface etc. Suitable for capturing changes.
[0080]
To simply observe a monochrome image of a certain band as a monochrome image, M4 may be set. To take advantage of the characteristics of each band and mix and output a plurality of bands at a certain ratio, M5 The coefficient can also be set as follows.
[0081]
As described above, according to the present embodiment, in addition to the effects of the first embodiment, the screen does not become extremely dark when the filter is changed to switch from the normal observation to the narrow-band filter observation. Therefore, it is possible to obtain an illumination light amount with sufficient brightness that can be observed. Furthermore, since it is possible to select which band of the plurality of filters is used for observing the image, the user can obtain an optimal observation image in accordance with the use situation.
[0082]
In this embodiment, the rotational filter 14 has a double configuration. However, if only the B filter needs to be changed to obtain an effect on the image, the rotational filter can also have a single configuration. As shown in FIG. 23, the rotary filter 14 is composed of four filters. For example, as shown in FIG. 24, the filter characteristic has a configuration in which only the B filter is narrowed. The purpose of this is to improve the contrast of a biological structure such as a blood vessel near the surface by narrowing the band of the filter by utilizing the fact that the depth of light near the wavelength band to the living body is shallow. . By adopting such a configuration of the rotary filter 14, the user can obtain an optimum observation image only by instructing band switching according to the observation situation without performing filter switching.
[0083]
【The invention's effect】
As described above, according to the present invention, it is possible to separate and visually recognize desired deep tissue information near the tissue surface of a living tissue.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of an endoscope apparatus according to a first embodiment of the present invention.
2 is a configuration diagram showing the configuration of the rotary filter of FIG.
FIG. 3 is a diagram showing spectral characteristics of a first filter set of the rotary filter of FIG. 2;
4 is a diagram showing spectral characteristics of a second filter set of the rotary filter of FIG. 2;
FIG. 5 is a view showing a layer direction structure of a biological tissue observed by the endoscope apparatus of FIG.
6 is a diagram illustrating a state in which illumination light from the endoscope apparatus of FIG.
7 is a diagram showing each band image by frame sequential light transmitted through the first filter set in FIG. 3;
8 is a diagram showing each band image by frame sequential light that has passed through the second filter set of FIG. 4;
9 is a diagram for explaining dimming control by the dimming circuit of FIG. 1;
10 is a configuration diagram showing the configuration of the image processing circuit of FIG. 1. FIG.
11 is a diagram showing a color image of a narrowband RGB image obtained by the image processing circuit of FIG.
12 is a diagram for explaining the creation of a matrix that maintains the average color tone in the 3 × 3 matrix circuit of FIG. 10;
13 is a diagram showing an example of setting of the LUT in FIG.
14 is a configuration diagram showing a configuration of a modified example of the color conversion processing circuit of FIG. 10;
FIG. 15 is a configuration diagram showing a configuration of an endoscope apparatus according to a second embodiment of the present invention.
16 is a configuration diagram showing the configuration of the image processing circuit of FIG.
17 is a configuration diagram showing the configuration of the color adjustment circuit of FIG.
18 is a diagram showing the concept of hue and saturation in the L * a * b * color space in the color adjustment circuit of FIG.
FIG. 19 is a configuration diagram showing a configuration of an endoscope apparatus according to a third embodiment of the present invention.
20 is a configuration diagram showing the configuration of the rotary filter of FIG.
21 is a graph showing spectral transmission characteristics of the G2, B2a, and B2b filters of the rotary filter of FIG.
22 is a configuration diagram showing the configuration of the band selection circuit of FIG. 19;
23 is a configuration diagram showing a configuration of a modified example of the rotary filter of FIG.
24 is a diagram showing spectral transmission characteristics of the rotary filter of FIG.
[Explanation of symbols]
1. Endoscope device
2 ... CCD
3 ... Electronic endoscope
4. Light source device
5 ... Observation monitor
6. Image filing device
7 ... Video processor
10 ... Power supply
11 ... Xenon lamp
12 ... Heat cut filter
13 ... Aperture device
14 ... Rotation filter
15. Light guide
16 ... Condensing lens
17 ... Control circuit
18 ... Rotary filter motor
19: Mode switching motor 19
20 ... CCD drive circuit
21 ... Objective optical system
22 ... Amplifier
23. Process circuit
24 ... A / D converter
25 ... White balance circuit
26 ... Selector
27, 28, 29 ... Synchronized memory
30. Image processing circuit
30a ... Color conversion processing circuit
31, 32, 33 ... D / A circuit
34 ... Coding circuit
35 ... Timing generator
41 ... Mode selector switch
42. Mode switching circuit
43. Light control circuit
44. Dimming control parameter switching circuit
61 ... 3 × 3 matrix circuit
62a, 62b, 62c, 63a, 63b, 63cLUT ...
64 ... Coefficient changing circuit

Claims (2)

An illumination light supply means for supplying illumination light including a visible light region, an endoscope having an imaging means for illuminating the subject with the illumination light and imaging the subject with return light, and an imaging signal from the imaging means In an endoscope apparatus provided with signal processing means for processing,
A plurality of wavelength regions of the illumination light, arranged in an optical path from the illumination light supply unit to the imaging unit, and distributed according to the depth of light with respect to the subject. A band limiting unit that limits the band of at least one wavelength region to narrow the band image of the discrete spectral distribution of the subject on the imaging unit;
The signal processing means applies the imaging signal whose band is narrowed by the band limiting means in the wavelength region allocated according to the depth of light with respect to the subject according to the arrangement state of the band limiting means. An endoscope apparatus that performs predetermined color conversion processing . The illumination light supply means includes
The endoscope apparatus according to claim 1, further comprising a light amount control unit configured to control the light amount of the illumination light for each wavelength region in accordance with the limitation of the band limiting unit.

Images