JP3904257B2 - Imaging device - Google Patents

Description

この（数１）は本発明の実施の形態として或る仮定の上に設定したものである。この仮定とは、１つのサブ測光値Ｓ（Ｎ）の最大値（３，４５６，０００）がビデオ信号の１２０％に対応し、ビデオ信号の０％がディジタル出力（サブ測光値）の０に対応するといった対応関係を設定し、この範囲で小さい方から大きい方に幾つかの目標値となり得る値を設定したものである。
【００２２】
ビデオ信号レベル１２０％が３，４５６，０００で０％が０であるという対応関係の上に、上記サブ測光値の候補値ＦＫを対応させ、Ｆ１として３０％（ビデオレベルであるからＩＲＥという単位で称呼することもある）、Ｆ２として４５％、Ｆ３として６０％、Ｆ４として７５％、Ｆ５として９０％を各設定する。
上記においては、６０％程度をおおよそ中間的なビデオ信号レベルだと見ており、１２０％は既述の通り、８ビットで量子化したディジタル信号の最大値に対応付けているため、これ以上明るい状態は存在しないとの仮定に立っている。
【００２３】
上記に定義のＳ（Ｎ），Ｄ（Ｎ），ＦＫといった各値を用いて、実際にどのような測光値の演算やサブ目標値の設定が行われるかについて適用される演算式を例示しながら以下に具体的に説明する。
先ず、測光値の演算式として、次の（数２）が用いられる。
【数２】

【００２４】
（数２）にはサブ目標値設定と測光値演算の双方の考え方が含まれている。即ち、記号ＴＳについては測光値を既述の例ではＳとしてきたのに対し、図１の実施の形態のブロック９２（測光値演算）で演算される最終的な測光値、従ってトータルの測光値という意味で、この記号ＴＳを当てたものである。
ＤやＦＫについては上述同様である。ρという記号が新たに導入されている。これは必要に応じて用いられる重み付けの係数であり、これについては後に詳述する。
【００２５】
（数２）の右辺の分子に注目すると、ＤからＦＫを引いた形になっており、これはサブ測光値から目標値ＦＫを引いたということである。
（数２）では上記引いた結果としての差の総和を求めており、これは即ち各サブ目標値とこれに対応する各サブ測光値との偏差の総和を求めるという本願特許請求の範囲、請求項１の一つの要件に相応するものである。
【００２６】
（数２）の右辺の分母に注目すると、ここに目標値ＦＫがあり、これは即ち各サブ目標値とこれに対応する各サブ測光値との偏差に関して規格化を行うということであって、本願特許請求の範囲、請求項２に相応するものである。
【００２７】
また、（数２）の右辺には重み付けの係数ρが掛けられるようになされており、これは即ちレベル規格化手段によって規格化された各値に対して所定の重み付けを行うということであって、本願特許請求の範囲、請求項３に相応するものである。
【００２８】
（数２）ではΣがＫとｉについて１〜５までとられている。一方、上記サブ測光値の候補値ＦＫについては既述の（数１）によって定義されているので、Ｋが１〜５のいずれであるかに応じて異なる値をとる変数となる。これに対しＤは、その定義自体は既述の通りＳを小さい値の順に並べ替えたものであるが、その中の引き数として５（Ｋ−１）＋２という式がとられている。これはｉとＫが１〜５までの任意の値をとるときにＤの括弧の中の引き数は１〜２５をとることを意味する。即ち、元々Ｓ（Ｎ）というものが２５個あって、それを並び替えたＤ（Ｎ）も２５個あるので、丁度１：１に対応して該当するｉとＫに応じたＤが存在する。或るＫとｉとを指定するとＤの括弧の中の引き数としては１〜２５のうちのいずれか１つの値が定まり、重複することはないので、換言すればＤの１〜２５のいずれかを指定すれば、この指定されたＤに対応するＫとｉとが定まるといった関係にある。この関係に注目すると（数２）の物理的意味を理解し易い。
【００２９】
（数２）によって表現される現象の例として、サブ測光値Ｓが７であるサブ測光エリアから得られるＳ（７）というものに対してどのような演算が行われるかについて説明する。
先ずサブ測光値Ｓについては並び替えを行うため単にＳ（７）というだけではは演算にのらない。この場合のＳの値が暗い方から見た順番で１８番目だったとすると、Ｓ（７）がＤ（１８）であるということになる。従って、サブ測光値Ｓが７であるということは（数１）の中ではＤ（１８）という形で適用されることになる。Ｄの引き数１８に対応するＫとｉとは何かを見ると（図２参照）、１：１に対応してＫは４，ｉは３であることが判る。
【００３０】
上記の場合にＳ（７）に対するサブ目標値（ここではサブ目標値という意味でＭという記号で表記する）を設定することを考える。これは即ち、Ｓ（Ｎ）に対するサブ目標値をＭ（Ｎ）とすると、Ｓ（７）に対するサブ目標値Ｍ（７）を設定することを考えるということであり、上記の場合ではＫが４であるから、サブ目標値Ｍ（７）＝Ｆ４であるということになる。このＦ４は（数１）で定義されているものであり、具体的には７５ＩＲＥ相当数値である２，１６０，０００が選択されたことになる。
【００３１】
上述のようにサブ測光エリア１〜２５に対応するサブ目標値１〜Ｓ（２５）は全て上記のようにして設定することが可能であり、結果的にそれぞれに対応して所定のサブ目標値が与えられることになる。これは即ち、測光値Ｓを並び替えた測光値Ｄに対して各該当するＫ（サブ目標値の候補のうちのいずれであるか）が定まるということである。本例でのサブ目標値の決まり方について説明すると、小さい順に並べた２５個のデータを５個ずつの群に分類し、最も小さい群に対してはＦ１を、次に小さい群に対してはＦ２を、中間の群に対してはＦ３を、次の群に対してはＦ４を、最も大きい群に対してはＦ５を対応させる。これは既述の（数１）の意味するところである。
【００３２】
上記の点は、目標値設定手段は、各サブ測光値に対してその値の大小に係る序列を形成し該序列に対応するように各サブ目標値を設定するものであるという本願発明の撮像装置での一つの限定的局面（５）での特徴に相応し、また、サブ目標値設定手段は、上記各サブ測光手段により形成された序列に従った各サブ測光値に各対応してサブ目標値として設定され得る候補値の群の中から一義的に所定の値をサブ目標値として選定する手段を含むものであるという本願発明の撮像装置での更に限定された局面（７）での特徴とするところに相応する。
【００３３】
次に、露出制御をどのようにして行なうかについて説明する。説明を簡単にするために重み付けの係数ρは全て１であると仮定する。理想的な制御が行われた状態を仮定すると、その状態においては各サブ測光値は該当するサブ目標値に一致して制御の偏差は０となる筈であるから、（数２）のＴＳ＝０となる。換言すれば、ＴＳ＝０を制御の目標値として設定するのが自然であるということを意味している。尤も、様々な露出の補正を行なうことを配慮した場合においては、必ずしもＴＳ＝０が制御の目標値として設定されるとは限らないことは言うまでもない。但し、本実施の形態では、ＴＳ＝０を制御の目標値として設定する。制御の目標値設定の動作は、図１のブロック図におけるマイクロコンピュータ９内での（ｃ）露出制御判断処理９３において実行される。
【００３４】
この露出制御判断処理動作において、ＴＳ＝０であるときは露出が適正であるということであるから、露出状態は現状を維持するようになされ、変更は行われない。
ＴＳが０より大きいときには、測光値の方が目標値を上回っているということであるから、露出オーバーと判断して露出を下げる方向に制御動作が行われる。反対にＴＳが０より小さいときには、測光値の方が目標値を下回っているということであるから、露出アンダーと判断して露出を上げる方向に制御動作が行われる。
上記の露出を上げたり下げたりする調節動作は、図１のブロック図について説明したように絞りまたは撮像素子のシャッタードライバーを制御して、絞り値やシャッター値が調節される。
上述のような制御を繰り返し行うと、フィードバックループを形成することになり、偏差が０、即ちＴＳ＝０となるように収束して安定する。
上記の点は、露出制御手段は、上記測光値を所定の値に収束すべく露出に関するパラメータを変更してフィードバック制御を行うものであるという本願発明の撮像装置での一つの限定的局面（４）での特徴に相応する。
【００３５】
（数２）での重み付け係数ρについて次に説明する。ρのサフィックスＫとｉについて今一度確認すると、Ｋとは目標値ＦＫのＫと共通に用いられる数字であり、Ｋの１〜５に対応して目標値がそれぞれ暗い目標値から明るい目標値に対応しているという形になっている。これら各目標値に対応する測光値も、序列によって並び替えられたＤについての値であり、Ｋの１〜５に対応して測光値がそれぞれ暗い測光値から明るい測光値に並んで対応しているという形になっている。従って、重み付け係数ρKiのｉについては任意の値をとるものとして扱えるが、Ｋについてはρ1iやρ2iといった比較的暗い情報（若しくは目標値）に対応する重み付け係数についてはこの値を１という、先の例での仮定におけるものと同じ値にしておき、明るい方のρ4iやρ5iといったものについては重み付けの値を減らすようすると低輝度重視型の測光制御を行なうことになる。
【００３６】
このような低輝度重視型の測光制御を行なう場合の一例としては：
ρ1i＝ρ2i＝１；ρ3i＝１／２；ρ4i＝ρ5i＝１／４に設定する。
また、上記とは反対に高輝度重視型の測光制御を行なう場合の例では：
ρ1i＝ρ2i＝１／４；ρ3i＝１／２；ρ4i＝ρ5i＝１に設定する。
更に、中輝度重視型の測光制御を行なう場合には例えば：
ρ1i＝ρ5i＝０；ρ2i＝ρ4i＝１／２；ρ3i＝１に設定する。
この中輝度重視型のように重み付け係数ρを０にする、即ち、極めて明るい部分と極めて暗い部分については０にするということで、それらの部分のデータを無効にすることができる。換言すれば、重み付け係数ρを適用するという概念の中にはこの係数ρを０にすることによってそれに該当するデータを無効にするという意味を含んでいる。
【００３７】
重み付け係数ρの選択の仕方は設計に応じて任意にできるが、ディジタルコンピュータ上で扱う場合には２のｎ乗倍として設定することができれば演算の負担を軽減することができる。
特に、２のｎ乗倍をとる場合には、ｎを０または負の数（正の数ではないという意）として選択すると、上記の例のように１／２，１／４，１／８といった数字の系列から選択することとなり、選択の対象となる数字の増加に応じて桁数を増やす必要がなく、演算の簡素化が計られるといった利点がある。
【００３８】
次にレベルの規格化ということについて説明する。既述の（数２）ではレベル規格化の形として、分子に目標値と測光値との差（偏差）を置き、それをサブ目標値で割り算するという形をとったが、規格化の形としては、上記以外に、次の（数３），（数４）示すような形をとることもできる。
【数３】

【数４】

この（数３）では分母にＤ＋ＦＫを置き、（数４）では分母にＤだけを置く形をとる。これらは、いずれにしてもレベル規格化の目的が測光エリアに対応する被写体の明るさの影響がなるべく少なくなるように、即ち、明るい部分のデータと暗い部分のデータとがなるべく対等に扱われるということを目指すところにあるということから、そのような、部分的値の影響が別段に大きくなってしまうことを回避する意味をもつものであれば、種々の形のものが適用可能であるという考えに立つものである。
【００３９】
但し、理想的には、（数３）のような形をとることになると言える。その理由は、この（数３）ものでは分子側にある差の値を平均値で規格化したものに相当する意味もつからである。
尚（数２）の場合では、分母にＤを含まないようにしてあるが、これは、分母側にＤの値が入ってくると、そのときのサブ測光値の如何によって規格化の定数が変わってしまうことが必ずしも望ましくはない場合があり得るためである。
【００４０】
次に、本願発明の第２の実施の形態について以下に説明する。この第２の実施の形態では、ブロック図上では図１と同じであり、この中での、ブロック９１および９２内での処理が異なり、他は同様である。
この実施の形態では、その測光値演算として（数５）の演算が実行される。
【数５】

この（数５）の右辺第１項はＴＳ＝Σ・Σという（数２）と全く同様の形式がとられているが、右辺第２項として、
【数６】

が付加されている。この（数６）は画面上の位置によってデータの処理を行なう際の重み付けを付加する項となっている。
【００４１】
特に留意すべき点は、右辺第１項の（数２）と全く同様の部分はそのデータがどのサブ測光エリアに該当するものか（位置）には全く無関係であり、専らその測光値が明るさの程度の序列においてどのような順番に該当するかに依拠してサブ目標値の設定や重み付けを行っているのに対し、右辺第２項の（数６）の部分はそのデータがどのサブ測光エリアに該当するものか（位置）に応じた重み付けを行っている点である。
ここに提示の例ではこの右辺第２項について共通のＦ３という値を適用する。このＦ３とは、（数１）の定義に従って見ると、中間的値であると言うことができる。これはビデオレベルでは６０％程度に相応し、このＦ３をサブ目標値とし、規格化もこのＦ３によって行なう。この規格化はいわば「レベル規格化」ということであり、本願発明において従来の装置との比較において特段の効果を生じさせている要件でもある。
【００４２】
この実施の形態において中央重点測光の特性を与えるための重み付けを行なう場合、一例としてはρj のｊが１〜６，１０，１１，１５，１６，２０〜２５については０とすればよい。これは、２５個のサブ測光エリアのうち外側の１周の重み付けを０としてそこからのデータを用いないということである。一方、ρ7 ，ρ8 ，ρ9 ，ρ12，ρ14，ρ17，ρ18，ρ19については重み付けを１／２とする。これは、中心を取り囲む１周の領域については重み付けを１／２とする意である。ρ13が中心部の領域であり、ここに１の重み付けをする。以上のような重み付けをすれば、右辺第２項の（数６）の部分は各サブ測光エリアでの輝度値に関わらず中央部を重点的に測光することになる。
【００４３】
本願発明で特に留意すべきは、（数５）では、右辺第１項の（数２）と第２項の（数６）との双方が加味されるということである。
例えば、或る１つのサブ測光エリアだけに注目したとき、（数５）の中で１回だけ現れるのではなく、２回現れる場合があり得る。具体的には、右辺第２項の（数６）でρj が０でないようなサブ測光エリア、即ち、重み付けとして１／２または１を与えられたエリアのデータについては、右辺第１項の（数２）で輝度のレベルについての序列を与えられたという設定根拠に拠って演算を施すことによって既に一定の重み付けがなされており、更に、この右辺第２項でどのサブ測光エリアに該当するものか（位置）に応じた重み付けがなされているということである。
【００４４】
更に具体的には、Ｓ（１２）というエリアがＤ（４）である場合を想定すると、（数５）の右辺第１項の（数２）中で暗い方から４番目であるデータということは最も暗い部分に該当するサブ測光値であるということであり、そのときのサブ目標値がＦ１として処理されることとなり、Ｆ１で規格化されて、その重み付け係数は１ということになっている。
一方、（数５）の右辺第２項の（数６）では、中心部を取り囲んで位置するエリアであるということで、目標値はＦ３という中間的値がとられ、このＦ３で規格化されて、重み付け係数は１／２ということになっている。
【００４５】
同一のエリアのデータでも異なる根拠に基づいて処理されたものが、それぞれ別の重み付けをもって加算され、その結果により総合的な判断としてＴＳに関して明るいか暗いかの意味が反映された結果を得ることになっている。
即ち、（数５）に拠る実施の形態では、エリア的（サブ測光エリアの位置的）判断も輝度レベルの序列に対応した判断も双方同時に勘案したものとなっており、本発明の一つの限定的側面として極めて特徴的な点である。効果の点でも、サブ測光エリアの位置的分布に関する要素と輝度レベルの程度との双方が加味された適切な露出制御が実現できるという点で特段に優れている。
【００４６】
上述した第２の実施の形態について、その変形例として、必ずしも上記の２つの設定根拠のみに限定されることなく、他の設定根拠の項を更に付加することも考えられる。
即ち、サブ目標値との差で処理した項が多数連なってくる場合でも、或いは、種々考慮すべき項目を付加したい場合にも、これらの項を単純に加算する形をとることで、その項（項目）に関する情報をＴＳに反映させることができる。その項（項目）をどの程度反映させるかについては重み付け係数の処理により任意に設定できる。従って、第３、第４の項を追加的に付加していくことが可能である。尚、上述した例では、主として輝度出力を処理していくものについて説明したが、ビデオ信号から得られる情報は輝度情報のみならず、色情報に関するデータ等（例えば色度値）も得られるため、同一のエリアから抽出されたデータでも、その色度値がいくつであるかということに応じて異なる目標値および重み付けを行ったような項を追加することも一つの好適な実施の形態となる。
【００４７】
次に、サブ測光値に対するサブ目標値の設定に関して、単純に輝度レベルでの序列に従うだけでなく、輝度の分布についての判断も加味して、このサブ目標値を予め用意した複数のサブ目標値の候補の中から選択するようにした第３の実施の形態について説明する。
この実施の形態では（数７）によって定義されるＡk という値を用いる。
【数７】

この（数７）でｋは０〜５の整数とする。
（数７）の分母は５で、分子は第１項がｋ×ＭＡＸ｛Ｓ（Ｎ）｝、第２項が（５−ｋ）×ＭＩＮ｛Ｓ（Ｎ）｝である。
この（数７）の意味するところを図３を参照して説明すると、ｋに０や５を代入したときには、そのままＭＩＮ｛Ｓ（Ｎ）｝やＭＡＸ｛Ｓ（Ｎ）｝の値となるようにされている。またｋがその間の１〜４の値をとるときには、丁度ＭＡＸとＭＩＮであるＡ5 とＡ0 との間を５等分したようないずれかの値をとる。
【００４８】
上記のようなＡk を用いる理由は、ＴＳを算出するための次の（数８）の中で係数であるαN,K というものを用いた場合分けの処理を可能にするためである。
或るエリアＮについてはそのサブ測光値Ｓ（Ｎ）がＭＡＸからＭＩＮの間の値として必ず存在する。このサブ測光値Ｓ（Ｎ）を図３に表されたような５等分されたレベル範囲のいずれに属するかに応じた形、即ち、Ｓ（Ｎ）がＡ0 〜Ａ1 間か、Ａ1 〜Ａ2 間か、Ａ2 〜Ａ3 間か、Ａ3 〜Ａ4 間、Ａ4 〜Ａ5 間かといった形で分類する。このようなＡk を用いた（数８）は、次のとおりである。
【数８】

この（数８）を分析的に見ると、サブ測光値Ｓ（Ｎ）からサブ目標値ＦＫを引いたものを分子にＦＫを分母とする値に対して２つの係数、即ち、係数αN,K と重み付け係数ρK （明るさに応じた重み付けをするためのもの）を乗じたものについてK が１〜５までのΣを用意しておき、このΣについてＮに関して２５のエリアに対応するＮ＝１〜２５までのΣをとるということである。
係数αN,K の定義として、Ｓ（Ｎ）がＡk-1 からＡk までの間にあるときには１となり、それ以外のときには０となるものとしている。
【００４９】
端点での処理としては、Ｓ（Ｎ）＝Ａ5 も１としているが、考え方としては、αが１か０かのいずれになるかといったことを上記のように場合分けすることによって、図３の各領域（レベル範囲）のいずれにＳ（Ｎ）の値が属するかに対応させている。即ち、或るＫ番目の段階に入っていればαが１になり、入っていないときには０になるという形で演算が行われるため、結果的に５段階の分類の一番上のＡ4 〜Ａ5 間にあるサブ測光値に対してはＦ５というサブ目標値が与えられる。もし、中間のＡ2 〜Ａ3 間にサブ測光値があればＦ３というサブ目標値が与えられる。即ち、各Ｓ（Ｎ）に対するサブ目標値は被写体の輝度分布を５段階に分類し、それぞれの明るさに応じてＦ１〜Ｆ５を割り当てることになる。
【００５０】
既述の第２の実施の形態では、サブ測光値を明るさの順番に並び替えてそれを５つずつに区切ってＦ１〜Ｆ５を割り当てていたので、実際には非常に明るいものが多くて１０個明るいところが存在して残りが暗いといった場合でも、無条件に５個刻みで処理をしていたところ、この第３の実施の形態では、輝度の分布状態を反映させた処理を行なうものであり、より適切な露出制御が行われ得る。
【００５１】
次に、本願発明の第４の実施の形態について以下に説明する。この第４の実施の形態は既述の第３の実施の形態が予め設定したサブ目標値の候補のうちから該当するサブ目標値を選択するようにしていたのに対し、最適なサブ目標値を演算によって算出するようにした点が異なる。
この場合における最適なサブ目標値を求めるための演算式が次の（数９）である。
【数９】

（数９）におけるＭ（Ｎ）が、第１の実施の形態について述べたＳ（Ｎ）に対するサブ目標値に相応するものである。
この場合のＭ（Ｎ）は、（数９）のただし書きの式により直接算出されるものである。このただし書きの式においてもＭＡＸ｛Ｓ（Ｎ）｝を用いて計算するようになっているが、この式の意味するところは、図４を参照して容易に理解される。既述の説明においてはＦの値としてはＦ１〜Ｆ５までであったが、図４中でＦの値としてＦ０，Ｆ６が設定されている。しかしＦ〜という記号（値）は既述の（数１）で定義されるものであり、この式のＫに０，６を代入すれば、これらＦ０，Ｆ６が求められる。これはビデオ信号レベルとしては１５％および１０５％に対応するものであり、かなり暗い値とかなり明るい値の代表として設定してある。
【００５２】
上記においてどのような値を対応させるかといったことは設計事情に応じて決められることである。例えば、既述のＦ１をＦ０の代わりに、既述のＦ５をＦ６の代わりにそれぞれ適用しても測光系としては動作するものであるが、ここでは上記のＦ０，Ｆ６の方がより適切な特性を得ることが期待できる。
（数９）のただし書きにおけるＭ（Ｎ）の設定は、図４に示されたようなサブ測光値Ｓ（Ｎ）の様々な値の中で今着目しているＳ（Ｎ）の値のＭＡＸ，ＭＩＮに対する比率が、制御目標値として考えている明るい部分のＦ６、暗い部分のＦ０に対しての今回与えるべき目標値Ｍ（Ｎ）のＦ６とＦ０の間に対する比率となるようにするということを意味している。
【００５３】
当然に、被写体の明るさに応じて、明るいところは明るい目標値とし、暗いところは暗い目標値といった考え方が本願発明の基礎にあるため、これを究極までもっていくと、明るさの分布比率に相応した目標値を設定することが理想であることになり、この第４の実施の形態のようなものが考えられる。
ここで今一度確認すると、目標値Ｍ（Ｎ）は予め準備された目標値の候補値のいずれかのものとして選択されるのではなく、あくまでも演算によりそのときのサブ測光値のレベル分布に応じて与えられるということである。
【００５４】
次に、本願発明の第５の実施の形態について以下に説明する。この実施の形態はサブ目標値の設定やサブ測光値の演算方法について別段の特徴を求めたものではなく、これらについては既述の各実施の形態におけるそれを適用するを可とするものであり、サブ測光値の検出部について特徴を有する。
図５は本願発明の第５の実施の形態を表わすブロック図である。この実施の形態は、光学系を介した被写体光を光電変換して出力する撮像素子と、この撮像素子の出力信号をＡ／Ｄ変換してなるディジタル映像信号にこの映像信号に係る画面を複数のブロックに分割したときの各ブロック毎のＤＣＴ演算を施してＤＣＴ係数を得るためのＤＣＴ演算手段と、を更に備え、上記ブロックを上記サブ測光エリアとして適用したことを特徴とする。
【００５５】
図５の実施の形態を図１の実施の形態との比較により説明する。図１との対応部は同一の符号を附してある。図１ではブロック８のエリア別積分という回路部を有していたが、この回路部でプリプロセス４からの出力データをサブ測光エリア別に積分していた。これに対しこの図５の構成では、この積分を行なう回路部がない。これに代えてブロック６の記録プロセス回路の部分が詳しく描かれているように、この内部にＤＣＴ演算部６１が設けられている。
【００５６】
このＤＣＴ演算部６１は、記録プロセス部回路６に供給されるデータ量は非常に膨大なものでありこのまま記録すると記憶デバイスの所要の容量が大きくなり過ぎて不経済であるために、或いはまた、データの記録時間も長くなってしまう等の問題があるために、情報を圧縮してこのような問題に対処するものである。ＤＣＴ演算（Discrete Cosine Transformation）は上記のような目的で静止画の情報を圧縮するために近年多用されている手法の一つである。
このＤＣＴ演算においては、圧縮の対象とされる一つの広い画像領域（画素領域）を複数のサブブロックに分割し、そのサブブロック毎に内部のデータについて周波数領域への変換を行なう。この周波数領域に変換されたデータについて不要なデータを間引く処理を行なうことで情報量の圧縮が行われる。周波数領域への変換によって低周波領域、即ち、直流乃至直流に近い空間的に変化の少ない乃至は変化の無い係数（ＤＣ係数）が各ブロック毎に必ず算出される。
【００５７】
上記のＤＣ係数はそのブロックにおける輝度の平均値に相応するものである。そこで、ＤＣ係数はそのブロックにおけるサブ測光値として用い得る意味合いのものであり、この第５の実施の形態では、この点を利用している。即ち、ＤＣＴ演算を行なうためのサブブロックへの分割はサブ測光エリアへの分割に対応し、サブブロック毎のＤＣ係数はサブ測光値に対応している点に着目し、サブ測光エリアと等価な意味を持つサブブロック毎にサブ目標値を設定して、本願発明の特徴を生かした露出制御を行おうとするものである。
【００５８】
図６は図５の実施の形態における画面の分割状況を示す模式図である。図６は図２で説明した画面に相応するものであり、水平７６８×垂直４８０の画素よりなる。本実施の形態ではこのような構成の画面（撮像素子）を用いることを予定しているが、適用可能な画面（撮像素子）はこれに限定されるものではない。
図７は図５の実施の形態に適用可能な他の撮像素子による画面の状態を示す模式図である。この図７のものは、水平６４０×垂直４８０の画素よりなる。
ＤＣＴのブロックをどのように設定するかは設計上の選択事項であるが、通常最も多用されているものは、１ブロックを縦８画素、横８画素の８×８の６４画素よりなるブロックに分割するものである。この場合、図６の撮像素子では、エリアの数としてはブロック数９６×６０の５７６０ブロックとなり、図７の撮像素子ではブロック数８０×６０の４８００ブロックとなる。これらのブロック毎にＤＣ係数としてサブ測光値に相当する輝度信号の平均値が得られる。
【００５９】
これらのブロック数は、既述の２５個のサブ測光エリアに較べると非常に多くなっているが、本願発明は元来部分的エリア毎の状況を反映させたきめ細かな露出制御を行おうとするものであるから、演算機能部の能力の範囲内で極力サブ測光エリア（ブロック）を細かに区切った方が発明思想の趣旨に沿った理想的な制御ができることになる。寧ろサブ測光エリアを余り荒く（大きく）とると被写体の１つの領域とは見做せないような領域の境界が存在してしまうようなことも起こりかねない。例えば、同じ中間的な値の測光値が検出されたとしても、現実に中間的な輝度の被写体がそこに存在するといった場合と、明るいものと暗いものとが半分ずつ存在してその結果として中間的な値が検出されるといった場合とでは現象として意味が異なっている。本願発明の基調とする思想は、それぞれの場所が明るいとか暗いとか中間あるといった具合に測光値が得られていることを前提として、種々の測光の目標値や制御の方法を適用するといった思想であるため、上記のようにサブ測光エリアを多く（細かく）分割して設定するということは寧ろ好ましい結果が期待できることになる。
【００６０】
この第５の実施の形態以外についてはサブ測光エリアを２５とした場合について述べてきたのは、一つには説明の便宜上である。しかし、最低この程度に設定すれば、本願発明において期待される好適な露出制御を実現するに一応十分であるとも言える。また、サブ測光エリアを余り多く分割して設定しない場合は、種々の演算機能部の負担は軽減されるため、全体として簡素で安価な装置を実現できるといった利点も見逃せない。
従って、第５の実施の形態において、幾つかのブロックについて予め加算処理を行った結果について、それを各サブ測光値として扱うように構成することで構成の簡素化を計ることも考えられる。即ち、ＤＣＴの１ブロックを１サブ測光エリアとして対応させる構成をとることもできるし、また、ＤＣＴの複数ブロックを１サブ測光エリアとして対応させる構成をとることもできる。図５のブロック９内の破線図示のブロック「ブロック加算」は後者の場合に適用する上記加算処理のための機能ブロックである。
【００６１】
図１のブロック８におけるような、プリプロセスからの出力を即座に完全に積分処理してしまうような構成では、データ処理の速度が十分速くないと実現することが難しいが、ＤＣＴ係数出力のようにある程度の処理が行われた結果値に対して処理を行なうように構成すれば、マイクロコンピュータの中でこの演算処理を行なうことも可能になってくる。従ってこのような構成をとることにより、例えば、第１の実施の形態のように２５のエリアをもった処理についても特にエリア別積分回路を別途に設けずともＤＣＴ演算のＤＣ係数を利用することで同等の処理を実現することができる。
【００６２】
次に、本願発明の第６の実施の形態について以下に説明する。この実施の形態では次の（数１０）によって制御の目標値の設定を行なう。
【数１０】

この第６の実施の形態で、第１の実施の形態との相違点は、係数βK,i が更に乗じられている点である。この（数１０）のただし書きから理解されるように、Ｋ＝１〜４即ち、暗い方から２０番目までのデータ（Ｄ（１）〜Ｄ（２０））に関する項については係数βK,i は何等の影響も持たない。影響があるのはＫ＝５の場合のみであり、且つ、Ｄ（２０＋ｉ）≧Ｆ５のときだけである。尚（数１）によれば、Ｆ５＝２，５９２，０００であるからそのように記述してもよいが、記述の簡略化のために上記のように記した。また、数値３，４５６，０００は前述のようにＤ（Ｎ）のとり得る最大値である。今、Ｄ（２０＋ｉ）に対するサブ目標値はＫ＝５であるからＦ５である。従って、被写体の輝度分布が適当な範囲内にあれば制御の結果Ｄ（２０＋ｉ）＝Ｆ５に近づくであろうし、或いはまた、Ｄ（２０＋ｉ）＜Ｆ５で制御が安定したとすれば、最も明るい部類の被写体も、十分に低い（明る過ぎない）レベルの信号として再生されているということを意味しているから、問題はない。しかし、Ｄ（２０＋ｉ）＞Ｆ５の場合は「露出オーバー」たる結果を招来しているにも拘らず制御が安定してしまっているわけであるから、これは他の項に「露出アンダー」なるものが存在していることを示唆していることになる。
このような他の項が低輝度部であったとすると、結局「低輝度部は低い目標レベルに対してさえ露出アンダーであり、高輝度部Ｄ（２０＋ｉ）は高い目標レベルＦ５に対してさえ露出オーバーである」から、画像の所謂黒つぶれや白つぶれが発生する虞れがある。
【００６３】
そこで、これら所謂黒つぶれや白つぶれの発生を救うことが求められることになる。このような場合にとり得る制御は、低輝度部と高輝度部のうちいずれか一方の再現を放棄して、他方だけを救うようにすることである。
係数βK,i はＫ＝５の５つの高輝度項に関してはＤの値に応じて次の（表１）の値をとる。
【表１】

このため、「高輝度部が目標値Ｆ５の近傍以下のときには第１の実施の形態と同等の制御が行われるが、Ｆ５より大きくなるにつれて、その高輝度部の項の制御に対する寄与の度合いを抑制することにより、この高輝度部の忠実な再現を放棄する」といった作用を持つことになる。これによって、他の部分の再現性を確保することができる。
【００６４】
上記において「制御に対する寄与の度合いを抑制する」作用は、本願発明の撮像装置の一つの限定的局面（１０）における「測光演算手段は、上記サブ測光値が所定のレベル範囲を逸脱するとき、当該サブ測光値とこれに対して設定されるサブ目標値の演算結果値を抑圧する手段を含むものである」という特徴点における「サブ目標値の演算結果値を抑圧する」ことに相応するものである。
【００６５】
また、係数βK,i ＝０も起こり得る。この場合は、「抑圧」の概念には「無効にする」ことも含まれ得る。
更に、上述の（表１）の例ではβK,i はＤ（２０＋ｉ）の値に対して連続的に（漸増、漸減的に）変化しているが、これは制御が滑らかに自然に行われ、且つ、極限まで高低の輝度部の再現の両立を図る意味を持つものであるが、βK,i はこの限りでなく、適度に不連続に変化する値をとるようにしてもよい。
また更に、上述の例では「抑圧」は高輝度部を対象に行っているが、低輝度部を対象として行ってもよいことは勿論である。或いはまた、その他の条件に適用してもよいし、所要に応じて複数の条件に対して同時に適用してもよい。
更にまた、上述の例では第１の実施の形態を基礎として係数βK,i を追加的に乗じて実現したが、基礎とする構成は任意に選択でき、その実現手法（形式）も任意である。
【００６６】
尚、上述の各実施の形態においては、１画面の画素数は例えば７６８×４８０として説明したが、これがＮＴＳＣ方式の２：１のインターレースのビデオ信号における所謂１フレーム画面の画素数である場合には、実際の撮像装置での各種信号処理は所謂１フィールド画面を単位として実行される場合が多い。このように１フィールド画面を単位として処理を行なう場合は１画面の画素数を上記に比し垂直方向の数が半分であるとして見て７６８×２４０として各目標値の設定等を行えばよい。
【００６７】
また、上述の例はディジタルメモリを用いる電子スチルカメラであったが、本発明はビデオカメラレコーダー，銀塩スチルカメラ，銀塩シネマカメラをも含む種々の撮影装置に適用することができる。
【００６８】
以上の本願発明およびその種々の限定的局面で見た構成ならびにそれらにより解決される課題、発明としての効果について以下にまとめて記す。
【００６９】
（１）撮影画面の全体乃至はその一部を複数の領域に分割してなる各領域をサブ測光エリアとし、該測光エリア毎に当該撮影すべき被写体の輝度に対応したサブ測光値を得るためのサブ測光手段と、
上記サブ測光手段から出力された各サブ測光値に対して各別に到達すべき制御目標値であるサブ測光目標値を設定するサブ目標値設定手段と、
上記サブ目標値設定手段によって設定された各サブ目標値とこれに対応する上記各サブ測光値との量的（多値的）差分である偏差を各々求め、その偏差の総和を演算して当該撮影すべき被写体に関する露出制御量を求めるための演算手段と、
上記演算手段により求められた露出制御量に基づいて当該撮影に係る露出を上記偏差が総体的により小さくなるように制御する露出制御手段と、
を備えたことを特徴とする撮像装置。
【００７０】
上記（１）の発明以前の従来の技術では、撮影対象となる画面中の各部の異なる輝度を各別に考慮した最適な露出値を割り出すことは困難であった。
上記（１）の発明は、自動追尾装置やファジー推論回路等の複雑でコストの嵩む構成部を含まず簡素な構成で、且つ逆光シーン等を含む種々の被写体シーンに対して好適な露出を得ることのできる撮像装置を提供しようとするものである。
【００７１】
上記（１）の発明によれば、各サブ測光値に対して個別の目標値を与えるため明るい部分には明るい目標値が、暗い部分には暗い目標値が、中間的輝度の部分には中間的乃至平均的な目標値がそれぞれ与えられるようになり、撮像系の輝度レンジを考慮した露出が得られる。
【００７２】
上記（１）の発明おいて、 輝度レンジとは、換言すれば輝度再現領域とも言うべきものであり、既述のように撮像系は明るいところから暗いところまで全てを再現できるわけではないため、再現可能な範囲内でなるべく適切な露出制御を行なおうとした場合、上記（１）の発明のようにして露出制御することが望ましい。
【００７３】
（２）上記演算手段は、上記各サブ測光値と各対応するサブ目標値との間の各偏差に対してそれらのレベルの規格化を行うレベル規格化手段を備えてなるものであることを特徴とする上記（１）に記載の撮像装置。
【００７４】
上記（２）の発明以前の技術では、被写体の明るい部分の影響と暗い部分の影響とをどのように関連付けて露出制御に反映させるかについては何等特段の配慮がなされていなかった。
【００７５】
上記（２）の発明によれば、上記（１）の発明による効果に加えて、特に、被写体の明るい部分の情報量と暗い部分の情報量とが対等に扱われるため、全体として明るい部分の影響を強く受け過ぎるといったことがなくなるという効果を奏する。
【００７６】
尚、上記（２）の発明では、レベル規格化手段によってレベルに関する規格化を行っている。これは既述の「面積に関する規格化」を行うこととは俊別されるべき概念であり、このことは本願実施の形態においてもエリアに関する規格化を行って後、更にレベルに関する規格化を行っていることからしても理解されるであろう。即ち、面積に関する規格化がおこなわれているということは、同じ明るさの被写体があったときに、それぞれのエリアから同じ値が得られるということを保証するに過ぎず、異なる明るさの部分がある被写界（明るい被写体や暗い被写体が混在している画）に関して、明るい部分の影響と暗い部分の影響とをどのように露出の調節に寄与させるかについては全く調整不能である。
従来一般の、規格化或いは差をとるだけで規格化を行わない単純な重み付け加算減算という類の演算では、数値として明るい部分からの出力の占める割合が高くなり、この明るい部分の影響が支配的となりがちである。レベル規格化はこのような明るい部分の影響が支配的となる傾向を抑制するに有効である。
【００７７】
（３）上記演算手段は、上記各測光値とこれに対応する各サブ目標値との間の各偏差に対してそれらのレベルの規格化を行うレベル規格化手段と、該レベル規格化手段によって規格化された各値に対して所定の重み付けを行う重み付け手段と、を含んでなるものであることを特徴とする上記（１）に記載の撮像装置。
【００７８】
上記（３）の発明によれば、上記（１）の発明による効果に加えて、特に、被写体の輝度分布その他に関する重点的露出制御を行なうことができる。
【００７９】
（４）上記露出制御手段は、上記測光値を所定の値に収束すべく露出に関するパラメータを変更してフィードバック制御を行うものであることを特徴とする上記（１）、（２）又は（３）に記載の撮像装置。
【００８０】
上記（４）の発明によれば、上記（１），（２）又は（３）の発明による効果に加えて、特に、露出制御を非常に簡単に且つ安定して行なうことができる。
【００８１】
（５）上記サブ目標値設定手段は、各サブ測光値に対してその値の大小に係る序列を形成し該序列に対応するように各サブ目標値を設定するものであることを特徴とする上記（１）、（２）、（３）又は（４）に記載の撮像装置。
【００８２】
上記（５）の発明によれば、上記（１），（２），（３）又は（４）の発明による効果に加えて、特に、測光乃至露出制御のための演算が非常に簡単になる。序列というのは単純に大小関係で順番を並び変えるだけであるため、それを元に処理することで上記演算が非常に簡単になる。
【００８３】
（６）上記サブ目標値設定手段は、上記各サブ測光値に各対応して設定すべき上記各サブ目標値として異なる設定根拠に基づいた複数のサブ目標値を設定し、上記演算手段は、上記各サブ測光値に関して上記複数のサブ目標値毎に各別の演算を行って該各別の演算の結果から上記測光値を求める手段を含むものであることを特徴とする上記（１）、（２）、（３）又は（４）に記載の撮像装置。
【００８４】
上記（６）の発明によれば、上記（１），（２），（３）又は（４）の発明による効果に加えて、特に、画面上での輝度分布と輝度の序列との双方乃至はこれ以外の測光に関する要素を任意の配分で併せ考慮した微妙で高度な露出制御を行なうことが可能となる。
【００８５】
（７）上記サブ目標値設定手段は、上記各サブ測光手段により形成された序列に従った各サブ測光値に各対応してサブ目標値として設定され得る候補値の群の中から一義的に所定の値をサブ目標値として選定する手段を含むものであることを特徴とする上記（５）に記載の撮像装置。
【００８６】
上記（７）の発明によれば、上記（５）の発明による効果に加えて、特に、非常に簡単に露出制御に関する処理を行なうことができる。
【００８７】
このように予め準備された目標値から選ぶといった形式をとった場合、それら予め準備する候補値を例えばＥＥ・ＰＲＯＭに固定的に持つことになるが、この固定的な値を別途の手段により比較的簡単に書き換えることができるような構成にしておけば、更にその制御の種々のバリエーションを与え易く、しかもそれが制御系としては簡単な構成で行われるという特徴も付加される。このようにすることは、本願発明をシステム的に構成する場合特に大きな利点となる。
【００８８】
（８）上記サブ目標値設定手段は、上記サブ測光手段により形成された序列に従った各サブ目標値のレベルの分布を考慮した演算を行ってサブ目標値として設定され得る候補値の群の中から所定の値を選定してサブ目標値とする手段を含むものであることを特徴とする上記（５）に記載の撮像装置。
【００８９】
上記（７）の発明によれば、上記（５）の発明による効果に加えて、特に、画面上での輝度の序列と輝度分布との双方併せ考慮した微妙な露出制御を行なうことが可能となる。
【００９０】
（９）上記サブ目標値設定手段は、上記サブ測光手段により形成された序列に従った各サブ目標値のレベルの分布を考慮した演算を行ってサブ目標値を設定する手段を含むものであることを特徴とする上記（５）に記載の撮像装置。
【００９１】
上記（９）の発明によれば、上記（５）の発明による効果に加えて、特に、画面上での輝度の序列と輝度分布との双方併せ考慮した微妙な露出制御を行なうことが可能となる。
【００９２】
（１０）上記測光演算手段は、上記サブ測光値が所定のレベル範囲を逸脱するとき、当該サブ測光値とこれに対して設定されるサブ目標値の演算結果値を抑圧する手段を含むものであることを特徴とする上記（５）に記載の撮像装置。
【００９３】
上記（１０）の発明によれば、上記（５）の発明による効果に加えて、特に、画面上での高輝度部と低輝度部との輝度差が大き過ぎる場合だけいずれか一方の部分の再現性を優先する露出制御を行なうことが可能となる。
【００９４】
（１１）光学系を介した被写体光を光電変換して出力する撮像素子と、この撮像素子の出力信号をＡ／Ｄ変換してなるディジタル映像信号にこの映像信号に係る画面を複数のブロックに分割したときの各ブロック毎のＤＣＴ演算を施してＤＣＴ係数を得るためのＤＣＴ演算手段と、を更に備え、上記ブロックを上記サブ測光エリアとして適用したことを特徴とする上記（１）、（２）、（３）、（４）、（５）、（６）、（７）、（８）、（９）又は（１０）に記載の撮像装置。
【００９５】
上記（１１）の発明によれば、上記（１），（２），（３），（４），（５），（６），（７），（８），（９）又は（１０）の発明による効果に加えて、特に、この種の装置で一般化しつつあるデータ圧縮の一つの演算手法であるＤＣＴ演算を行なうために必須となる複数のブロックへの画面の分割を行なったときの各ブロックを利用して、別途新たにサブブロックの分割設定等を行わず、簡易な構成で露出制御を行なうことができる。
【００９６】
【発明の効果】
画面内の、明るい部分には明るい目標値が、暗い部分には暗い目標値が、中間的輝度の部分には中間的乃至平均的な目標値がそれぞれ与えられるようになり、撮像系の輝度レンジを考慮した好適な露出が得られる。
【図面の簡単な説明】
【図１】本願発明の撮像装置の一つの実施の形態としてのディジタル電子スチルカメラの構成を示すブロック図である。
【図２】撮像素子の光電変換面（有効撮像エリア）に対するサブ測光エリアの割り付け状況と各サブ測光エリアに対応するサブ測光値の値の大小による序列に従って各サブ測光エリアを仮想的に再配置した状態を示す模式図である。
【図３】本願発明の実施の形態での演算式（数７）を解説するための図である。
【図４】本願発明の実施の形態での演算式（数９）を解説するための図である。
【図５】本願発明の第５の実施の形態を表わすブロック図である。
【図６】図５の実施の形態における画面の分割状況を示す模式図である。
【図７】図５の実施の形態に適用可能な他の撮像素子による画面の状態を示す模式図である。
【符号の説明】
１ 撮像光学系
２ 絞り
３ 撮像素子
４ プリプロセス回路
５ 撮像プロセス回路
６ 記録プロセス回路
６１ ＤＣＴ演算部
７ メモリカードインタフェース
８ エリア積分回路
９ マイクロコンピュータ
９１ サブ目標値設定処理
９２ 測光値演算処理
９３ 露出制御判断処理
９４ ブロック加算
１０ アイリスドライバー
１１ イメージャドライバー[0001]
[Industrial application fields]
The present invention relates to an imaging apparatus incorporating an exposure control unit.
[0002]
[Prior art]
Conventionally, various types of exposure control devices applied to the imaging device have been proposed. As a general imaging device, there are a silver salt camera to which a normal silver salt film is applied and a video camera for electronically capturing images. In recent years, still video cameras for electronically capturing still images are also becoming popular. In these imaging apparatuses, various types of exposure control apparatuses are applied.
For example, since a silver salt camera records an image using a film, it is provided with a photometric sensor for measuring the amount of light related to photographing. In the early days of this type of camera, it was equipped with a single photometric sensor, but in recent years it has been equipped with multiple photometric sensors. It has been developed so as to include an area sensor for performing photometry for each photometric target area and performing exposure control based on the photometric value.
[0003]
On the other hand, for video cameras, an image sensor itself that converts an image of a subject into an electrical signal can also function as a photometric sensor. Therefore, a system that also uses an image sensor as an area sensor for photometry has already been realized.
In both the above-described photometry system for a silver halide camera and the photometry system for a video camera, an average value (average photometry value) of luminance is obtained over the entire area of the screen or almost the entire screen related to the photographing, and the average photometry value is determined in advance. In general, exposure control is performed such that control is performed so as to reach a single control target value. In addition, instead of performing control by setting a single control target value for the above-mentioned average photometric value, methods with various changes have already been proposed.
[0004]
For example, this is a method of measuring the luminance of only a part of the screen to be photographed, which is called partial photometry or spot photometry.
There is also a method (weighted average metering) in which photometric values of various parts in the screen are obtained and an average value is obtained after multiplying a weighting coefficient for each part.
Furthermore, there is a so-called peak metering method in which the photometric values of the brightest part and the darkest part in the screen are obtained and controlled so that these values become predetermined values.
[0005]
In each of the above methods, a single control target value is set corresponding to the photometric value, and control is performed so that the photometric value matches the target value. A method for variably setting the single control target value has been proposed in the past. However, the variable setting of the target value is merely a selective setting according to the situation, and there is no change in taking a single value at a certain point in time. Therefore, the technique is essentially the same as the conventional control method using a single control target value.
[0006]
The method of changing the level of the target value of control is applied, for example, when performing control corresponding to backlight. When a person standing at the window is a subject, a means to specially discriminate that the target subject is relatively dark and the target subject is relatively dark is set. The level can be variably set, or the screen can be divided into multiple areas and weighted for each area to average the brightness in the screen. Some are configured to change. As a method of changing the weight, there is a method in which the weight for a specific area is set to zero, that is, some information is excluded depending on the case. In addition, an algorithm that applies fuzzy inference as an algorithm for operations in various judgment operations has been proposed. Any of the above is in the category of a method of variably setting a single target value.
[0007]
[Problems to be solved by the invention]
However, in any of the conventional systems, after all, a single target value is set at a temporary point, and control is performed so that the photometric value at that time matches the target value. Therefore, it is inherently difficult to determine an optimal exposure value that takes into account different brightness of each part in the screen to be imaged.
[0008]
It is well known that in the conventional methods such as average metering, when a person at the window or the like is used as a subject, a so-called blackening, that is, a phenomenon in which the subject appears in full darkness occurs. This phenomenon is due to the fact that since the entire screen is viewed on average, the influence of a very bright part of the background is strong, and the person who is the main subject is relatively darkened. To avoid this, spot metering may be performed only on the center of the screen where such a main subject exists. However, if the position of the main subject deviates from the center of the screen, it will not work. There is a risk of malfunction when shooting a general scene. In order to deal with such problems, a method of tracking the photometry area with respect to the movement of the subject has been proposed, but the system for tracking the subject itself is very complicated and large-scale. In addition, it is still difficult to obtain sufficient tracking accuracy.
[0009]
Further, in the above-mentioned weighted average metering, each corresponding weighting is performed on each metering value when calculating the metering value. Although this weighting coefficient may be variably set, each metering value is multiplied by the weighting coefficient. Since the calculation of calculating the sum of these values is performed after obtaining the values, the influence of the subject with high brightness greatly affects the overall photometric value. There was a problem that the information could not be sufficiently reflected on the entire photometric value. For this reason, when shooting a scene of backlight, the so-called main subject is often crushed.
[0010]
The present invention does not include complicated and costly components such as an automatic tracking device and a fuzzy inference circuit in view of the above points, and is suitable for various subject scenes including a backlight scene and the like with a simple configuration. An object of the present invention is to provide an imaging apparatus capable of obtaining exposure.
[0011]
[Means for Solving the Problems]
  In order to solve the above problems, an imaging apparatus according to the present invention provides:
  Sub-photometry for obtaining a sub-photometry value corresponding to the luminance of the subject to be photographed for each photometry area, with each region obtained by dividing the whole or part of the shooting screen into a plurality of regions. Means,
  Each sub metering value output from the sub metering means should be reached separatelyControl target valueSub target value setting means for setting a sub metering target value;
  Between each sub target value set by the sub target value setting means and each sub photometric value corresponding thereto.Find each deviation that is a quantitative (multi-valued) difference,A calculating means for calculating a sum of deviations to obtain an exposure control amount relating to the subject to be photographed;
  Based on the exposure control amount obtained by the calculation means, the exposure related to the photographing is calculated.So that the deviation is smaller overallExposure control means to control;
An imaging apparatus comprising: ……… (1)
[0012]
[Action]
Each sub target value set by the sub target value setting means and corresponding to each sub photometric area, which is an area formed by dividing the whole or part of the photographing screen into a plurality of areas by the calculating means. In order to calculate the sum of the deviations from the sub-photometric values and obtain the exposure control amount related to the subject to be photographed, the image within the luminance range (luminance reproduction range) is photographed according to the situation of the object scene. It becomes possible.
[0013]
  The features of the present invention viewed in various limited aspects are listed below.ShiKeep it.
The calculation means normalizes those levels for each deviation between each sub-photometric value and each corresponding sub-target value.DoThe imaging apparatus according to (1) above, characterized in that it comprises level normalization means (2)
The calculation means includes level normalization means for normalizing those levels between each photometric value and each sub target value corresponding thereto, and normalization by the level normalization means The imaging apparatus according to the above (1), characterized by comprising weighting means for performing predetermined weighting on each of the obtained values (3)
In the above (1), (2) or (3), the exposure control means performs feedback control by changing a parameter relating to exposure so as to converge the photometric value to a predetermined value. The imaging device described (4)
The sub target value setting means is configured to form an order according to the magnitude of each sub photometric value and set each sub target value so as to correspond to the order. The imaging device according to 1), (2), (3) or (4) ......... (5)
The sub target value setting means sets a plurality of sub target values based on different setting grounds as the sub target values to be set in correspondence with the sub photometric values;the aboveThe calculation means includes means for performing a different calculation for each of the plurality of sub target values for each of the sub-photometric values and obtaining the photometric value from the result of the different calculation (1 ), (2), (3) or (4) image pickup device (6)
The sub target value setting means is uniquely defined from a group of candidate values that can be set as a sub target value corresponding to each sub photometry value according to the order formed by each sub photometry means. The imaging apparatus according to the above (5), including means for selecting a value as a sub target value (7)
The sub target value setting means performs a calculation considering the level distribution of each sub target value in accordance with the order formed by the sub photometry means, and selects from among a group of candidate values that can be set as the sub target value. The imaging apparatus according to (5), including means for selecting a predetermined value and setting it as a sub target value (8)
The sub target value setting means includes means for setting a sub target value by performing an operation considering a distribution of levels of each sub target value according to the order formed by the sub photometric means. The imaging device described in (5) above ... (9)
The photometric calculation means includes means for suppressing the calculation result value of the sub-photometric value and the sub target value set for the sub-photometric value when the sub-photometric value deviates from a predetermined level range. The imaging device according to (5) above (10)
An image sensor that photoelectrically converts and outputs subject light via an optical system, and a digital video signal obtained by A / D converting the output signal of the image sensor, and a screen related to the video signal divided into a plurality of blocks DCT calculation means for obtaining a DCT coefficient by performing DCT calculation for each block at the time, and applying the block as the sub-photometry area (1), (2), (3), (4), (5), (6), (7), (8), (9) or (10) The imaging device described in the above (11)
[0014]
Embodiment
FIG. 1 is a block diagram showing the configuration of a digital electronic still camera as an embodiment of an imaging apparatus of the present invention.
In FIG. 1, subject light that has entered the imaging optical system 1 from the subject side (not shown) passes through a diaphragm 2 and is formed on a photoelectric conversion surface of an imaging element 3 for photoelectrically converting an image by the imaging optical system 1. . The output of the image pickup device 3 is supplied to the image pickup process circuit 5 through the preprocess circuit 4. The preprocess circuit 4 performs so-called preprocessing prior to signal processing in the imaging process circuit 5, and in this example, includes an A / D conversion circuit within itself and performs digital signal processing. The imaging process circuit 5 performs various signal processing necessary for obtaining a signal suitable for the recording operation in the subsequent stage, such as color adjustment, on the signal supplied from the preprocess circuit 4, and outputs the signal to the recording process. Supply to circuit 6. The recording process circuit 6 performs processing such as compression of recording information, that is, digital image data, and the output data processed by the circuit is stored in a digital memory card as a recording medium through the memory card interface 7. If an EVF (Electronic Viewfinder) is provided, the recording process circuit 6 supplies image data to be displayed on the EVF. On the other hand, the signal output from the preprocess circuit 4 is supplied to an area integration circuit 8 described in detail later. The area integration circuit 8 is a means for calculating a sub-photometric value described later for performing exposure control in the apparatus according to the present embodiment, and relates to a digital video signal (luminance signal) supplied from the preprocess circuit 4. Execute integral operation. The output of the area integration circuit 8 is input to the microcomputer 9. Since the integration process for each area in the area integration circuit 8 is a simple addition operation process, it can be executed by a microcomputer if the processing speed is sufficient, but it is mounted on a normal product. The microcomputer having such a configuration is not suitable for performing digital integration processing. For this reason, it is necessary to prepare a separate integration circuit as in the illustrated example.
[0015]
The microcomputer 9 performs various processes on the data supplied from the area integration circuit 8, but the main processes are:
(A) Sub target value setting process ... 91
(B) Photometric value calculation processing ... 92
(C) Exposure control determination process ... 93
There is each processing.
In the sub target value setting in (a) above, for example, rank determination, level distribution determination, target value selection / calculation, and the like are performed.
In the photometric value calculation process of (b) above, for example, difference calculation, suppression process, level normalization, and weighting calculation are performed.
In the exposure control determination process of (c) above, for example, a control deviation is calculated by setting a control target value and comparing the control target value and the photometric value.
The output of the microcomputer 9 including the processing function units (a) to (c) described above is an iris driver 10 for adjusting the aperture and an imager for driving the image sensor 3 to obtain an element shutter function. It is configured to be supplied to the driver 11 and to appropriately control the aperture and shutter.
[0016]
The integration processing for each area in the area integration circuit 8 will be described below. Here, the “area” is a planar area where a subject exists, and this can be said to be a planar expansion of the photoelectric conversion surface of the image sensor 3 if viewed from another viewpoint. In the present specification, a plurality of regions virtually divided in the “area” are referred to as “subareas”. Further, the integration value related to each “sub-area” when the integration processing relating to the video signal level (luminance signal level) is performed for each “sub-area” is referred to as “sub-photometry value”. When the areas of the “sub-areas” are different from each other, it is common in this type of apparatus to normalize the area. The area referred to here corresponds to the number of pixels included in the “sub-area” in an apparatus that handles image signals (video signals) as digital data. That is, in this case, the number of pixels can be treated as a concept equivalent to the area. When the number of pixels included in each sub-area is equal, the sub-photometric value from each sub-area is the area. It will have an equal effect on the whole.
[0017]
On the other hand, when the area of one sub-area is twice that of the other sub-areas, even if a subject having the same brightness and brightness is photographed, the sub-photometric values from the sub-area having a large area are relatively In order to indicate a high value, sub-photometric values from sub-areas having an area twice that of the other are divided by 2 and processed so as to obtain an essentially equal output, and then sent to the subsequent process. It is necessary to do so. However, such processing can be performed as necessary, and in this embodiment, by setting the area of the sub-area to be equal, an output equivalent to that which has already been effectively standardized is obtained. You may comprise so that it may obtain. In this case, “area standardization” has been performed.
[0018]
FIG. 2 shows the sub-photometry areas virtually rearranged according to the allocation status of the sub-photometry areas with respect to the photoelectric conversion surface (effective imaging area) of the image sensor and the order of the sub-photometry values corresponding to each sub-photometry area. It is a schematic diagram which shows a state.
The image pickup device shown in FIG. 2 has a total number of pixels in the effective image pickup area of horizontal 768 and vertical 480, which is a specification that is relatively frequently used in electronic imaging such as an electronic camera. As an example of dividing the effective imaging area of this imaging device so that the areas of the sub-photometric areas are equal to each other as described above, the left and right ends of the area are each 9 pixels, and the upper and lower ends are 15 pixels. A frame-like pixel area to which no photometry is assigned is taken, and an area inside the frame-like pixel area is divided into 5 × 5 = 25 sub-photometry areas.
[0019]
As described above, as a result of dividing the effective imaging area and allocating the sub-photometry area, one sub-photometry area has a configuration composed of horizontal 150 pixels and vertical 90 pixels. The luminance photometric value for one sub-photometric area, that is, the sub-photometric value is 256 × 150 × 90 when quantization per pixel is performed with 8 bits. That is, the maximum value is 3,456,000. Of course, the minimum value is zero.
[0020]
Numbers 1 to 25 are assigned to all 25 sub-metering areas. This number is represented by N, and the sub metering value obtained from each sub metering area is represented by S (N). The maximum value of the sub-photometric value S (N) is 3,456,000 as described above, and the minimum value is 0. Here, all 25 sub-photometric values S (N) are collectively parenthesized and expressed as {S (N)}, and {S (N)} are arranged in order from the smallest value. The replacement is denoted as {D (N)}. That is, {S (N)} is correspondingly distributed in 5 × 5 = 25 regions inside the frame-like pixel region, and the {S (N)} are rearranged in order from the smallest value {D ( N)} forms a sequence as shown in FIG. Since {D (N)} are arranged in ascending order, when D is compared between N and N + 1 which is one more than that, D (N + 1) is always greater than or equal to D (N).
In other words, D (N) corresponds to any S (N), but D (N) corresponding to S (N) always has the above-described magnitude relationship.
[0021]
A value of FK is set as a candidate value for the sub-photometric value. FK is defined in the following (Equation 1).
[Expression 1]

This (Equation 1) is set on a certain assumption as an embodiment of the present invention. This assumption is that the maximum value (3,4456,000) of one sub-photometric value S (N) corresponds to 120% of the video signal, and 0% of the video signal is 0 of the digital output (sub-photometric value). Corresponding relationships such as corresponding are set, and values that can be several target values are set from the smaller to the larger in this range.
[0022]
On the correspondence relationship that the video signal level 120% is 3,456,000 and 0% is 0, the sub-photometric value candidate value FK is associated, and F1 is 30% (because it is a video level, the unit IRE F2 is set to 45%, F3 is set to 60%, F4 is set to 75%, and F5 is set to 90%.
In the above, about 60% is regarded as an intermediate video signal level, and 120% is associated with the maximum value of the digital signal quantized with 8 bits as described above, so it is brighter than this. Based on the assumption that no state exists.
[0023]
An example of an arithmetic expression applied to what kind of photometric value calculation or sub target value setting is actually performed using each value such as S (N), D (N), and FK defined above. However, it will be specifically described below.
First, the following (Expression 2) is used as a formula for calculating a photometric value.
[Expression 2]

[0024]
(Equation 2) includes both the concept of sub target value setting and photometric value calculation. That is, for the symbol TS, the photometric value has been set to S in the above-described example, whereas the final photometric value calculated by the block 92 (photometric value calculation) of the embodiment of FIG. In this sense, the symbol TS is applied.
D and FK are the same as described above. The symbol ρ has been newly introduced. This is a weighting coefficient used as necessary, which will be described in detail later.
[0025]
When attention is paid to the numerator on the right side of (Equation 2), FK is subtracted from D, which means that the target value FK is subtracted from the sub-photometric value.
In (Equation 2), the sum of the differences as a result of the above subtraction is obtained, that is, the sum of the deviation between each sub target value and each sub photometric value corresponding thereto is obtained. This corresponds to one requirement of Item 1.
[0026]
Focusing on the denominator on the right side of (Equation 2), there is a target value FK, which means that normalization is performed with respect to the deviation between each sub target value and each sub photometric value corresponding thereto. This corresponds to the scope of claims and claim 2 of the present application.
[0027]
The right side of (Equation 2) is multiplied by a weighting coefficient ρ, which means that a predetermined weight is applied to each value normalized by the level normalization means. This corresponds to the scope of claims of the present application.
[0028]
In (Equation 2), Σ is taken from 1 to 5 for K and i. On the other hand, since the candidate value FK of the sub-photometric value is defined by the above-described (Equation 1), it is a variable that takes a different value depending on whether K is 1 to 5. On the other hand, the definition of D is the definition itself, in which S is rearranged in the order of small values as described above, and the expression 5 (K-1) +2 is taken as an argument therein. This means that when i and K take arbitrary values from 1 to 5, the argument in the brackets of D takes 1 to 25. That is, there are 25 S (N) originally, and there are 25 D (N) rearranged, so there is a D corresponding to i and K corresponding to 1: 1. . When a certain K and i are specified, any one of 1 to 25 is determined as an argument in the parentheses of D, and there is no overlap. In other words, any of D 1 to 25 Is specified, K and i corresponding to the specified D are determined. Focusing on this relationship, it is easy to understand the physical meaning of (Equation 2).
[0029]
As an example of the phenomenon expressed by (Equation 2), a description will be given of what calculation is performed on S (7) obtained from the sub-photometry area where the sub-photometry value S is 7.
First, since the sub-photometric values S are rearranged, simply S (7) is not calculated. If the value of S in this case is 18th in the order viewed from the darker side, S (7) is D (18). Therefore, the fact that the sub-photometric value S is 7 is applied in the form of D (18) in (Equation 1). Looking at what K and i corresponding to the argument 18 of D are (see FIG. 2), it can be seen that K is 4 and i is 3 corresponding to 1: 1.
[0030]
Consider setting a sub-target value for S (7) (in this case, the sub-target value is represented by the symbol M) in the above case. That is, if the sub target value for S (N) is M (N), it is considered to set the sub target value M (7) for S (7). In the above case, K is 4 Therefore, the sub target value M (7) = F4. This F4 is defined by (Equation 1). Specifically, 2,160,000, which is a 75IRE equivalent value, is selected.
[0031]
As described above, the sub target values 1 to S (25) corresponding to the sub metering areas 1 to 25 can all be set as described above. As a result, predetermined sub target values corresponding to the sub target values 1 to S (25) can be set. Will be given. That is, each corresponding K (which is a candidate for the sub target value) is determined for the photometric value D obtained by rearranging the photometric values S. The method of determining the sub target value in this example will be described. The 25 data arranged in ascending order are classified into 5 groups, F1 for the smallest group and F1 for the next smallest group. F2 is associated with F3 for the middle group, F4 for the next group, and F5 for the largest group. This is the meaning of (Expression 1) described above.
[0032]
In the imaging according to the present invention, the target value setting unit is configured to form an order related to the magnitude of each sub-photometric value and set each sub-target value so as to correspond to the order. The sub target value setting means corresponds to the feature in one limited aspect (5) of the apparatus, and the sub target value setting means corresponds to each sub photometry value according to the order formed by each sub photometry means. The feature in the further limited aspect (7) in the imaging device according to the present invention, which includes means for uniquely selecting a predetermined value as a sub target value from a group of candidate values that can be set as target values, It corresponds to the place to do.
[0033]
Next, how exposure control is performed will be described. For simplicity of explanation, it is assumed that the weighting coefficients ρ are all 1. Assuming a state in which ideal control is performed, in that state, each sub-photometric value should match the corresponding sub-target value and the control deviation should be 0. Therefore, TS = 0. In other words, it means that it is natural to set TS = 0 as the control target value. However, it goes without saying that TS = 0 is not necessarily set as the target value for control when various exposure corrections are taken into consideration. However, in the present embodiment, TS = 0 is set as the control target value. The control target value setting operation is executed in (c) exposure control determination processing 93 in the microcomputer 9 in the block diagram of FIG.
[0034]
In this exposure control determination processing operation, when TS = 0, it means that the exposure is appropriate, so that the exposure state is maintained as it is and is not changed.
When TS is larger than 0, it means that the photometric value is higher than the target value, so that it is determined that the exposure is overexposed and the control operation is performed in the direction of decreasing the exposure. On the contrary, when TS is smaller than 0, it means that the photometric value is lower than the target value, so that it is determined that the exposure is underexposed and the control operation is performed to increase the exposure.
In the adjustment operation for increasing or decreasing the exposure, the aperture value or shutter value is adjusted by controlling the aperture or the shutter driver of the image sensor as described with reference to the block diagram of FIG.
When the above control is repeatedly performed, a feedback loop is formed, and the deviation is converged and stabilized so that the deviation becomes 0, that is, TS = 0.
The above point is that the exposure control means performs feedback control by changing a parameter relating to exposure so that the photometric value converges to a predetermined value. ).
[0035]
Next, the weighting coefficient ρ in (Expression 2) will be described. Confirming once again the suffixes K and i of ρ, K is a number commonly used with K of the target value FK, and the target value is changed from a dark target value to a bright target value corresponding to 1 to 5 of K. It is in the form of corresponding. The photometric values corresponding to these target values are also values for D that are rearranged according to the order, and the photometric values corresponding to 1 to 5 of K are arranged in correspondence from dark photometric values to bright photometric values. It is in the form of being. Therefore, although i of the weighting coefficient ρKi can be treated as an arbitrary value, K is 1 for the weighting coefficient corresponding to relatively dark information (or target value) such as ρ1i and ρ2i. If the same value as in the assumption in the example is used and the brighter values such as ρ4i and ρ5i are reduced, the low-luminance emphasis type photometric control is performed.
[0036]
Examples of such low-brightness metering controls include:
ρ1i = ρ2i = 1; ρ3i = 1/2; ρ4i = ρ5i = 1/4.
On the other hand, in the case of performing photometry control with emphasis on high brightness,
ρ1i = ρ2i = 1/4; ρ3i = 1/2; ρ4i = ρ5i = 1.
Further, when performing photometry control of medium brightness emphasis type, for example:
ρ1i = ρ5i = 0; ρ2i = ρ4i = 1/2; ρ3i = 1.
By setting the weighting coefficient ρ to 0 as in the medium luminance emphasis type, that is, to 0 for extremely bright portions and extremely dark portions, data in those portions can be invalidated. In other words, the concept of applying the weighting coefficient ρ includes the meaning of invalidating the corresponding data by setting the coefficient ρ to 0.
[0037]
The method of selecting the weighting coefficient ρ can be arbitrarily selected according to the design, but when handled on a digital computer, the calculation burden can be reduced if the weighting coefficient ρ can be set as 2 n times.
In particular, when n is multiplied by 2 to the power of n, when n is selected as 0 or a negative number (meaning not a positive number), 1/2, 1/4, 1/8 as in the above example. Therefore, there is an advantage that the number of digits does not need to be increased in accordance with an increase in the number to be selected, and calculation is simplified.
[0038]
Next, level standardization will be described. In the above (Equation 2), as a form of level normalization, the difference (deviation) between the target value and the photometric value is placed in the numerator and divided by the sub target value. In addition to the above, the following (Equation 3) and (Equation 4) can be taken.
[Equation 3]

[Expression 4]

In (Equation 3), D + FK is placed in the denominator, and in (Equation 4), only D is placed in the denominator. In any case, the purpose of level standardization is such that the influence of the brightness of the subject corresponding to the photometry area is reduced as much as possible, that is, the data of the bright part and the data of the dark part are treated as equal as possible. The idea that various forms can be applied as long as it has the meaning of avoiding that the influence of the partial value would be greatly increased. It stands for.
[0039]
However, ideally, it can be said that it takes the form of (Equation 3). The reason is that this (Equation 3) has a meaning equivalent to a value obtained by normalizing the difference value on the numerator side with an average value.
In the case of (Equation 2), D is not included in the denominator. However, when the value of D enters the denominator side, the normalization constant depends on how the sub-photometric value at that time is. This is because it may not always be desirable to change.
[0040]
Next, a second embodiment of the present invention will be described below. In the second embodiment, the block diagram is the same as that in FIG. 1, and the processing in the blocks 91 and 92 is different, and the others are the same.
In this embodiment, the calculation of (Equation 5) is executed as the photometric value calculation.
[Equation 5]

The first term on the right side of (Equation 5) is in the same form as (Equation 2) with TS = Σ · Σ, but as the second term on the right side,
[Formula 6]

Is added. This (Equation 6) is a term for adding a weight when data processing is performed according to the position on the screen.
[0041]
Of particular note is that the portion exactly the same as (Equation 2) in the first term on the right-hand side is completely irrelevant to which sub-photometry area (position) the data corresponds to, and the photometric value is exclusively bright. Sub-target values are set and weighted depending on the order in which they fall in the order of the degree, whereas the sub-value (number 6) in the second term on the right side indicates which sub-value The weighting is performed according to whether it corresponds to the photometric area (position).
In the example presented here, a common value of F3 is applied to the second term on the right side. This F3 can be said to be an intermediate value when viewed according to the definition of (Equation 1). This corresponds to about 60% at the video level, and this F3 is set as a sub-target value, and normalization is also performed by this F3. This standardization is so-called “level standardization”, and is also a requirement that produces a special effect in comparison with the conventional apparatus in the present invention.
[0042]
In this embodiment, when weighting is performed to give the characteristics of center-weighted photometry, as an example, j of ρj may be 0 for 1 to 6, 10, 11, 15, 16, 20 to 25. This means that the outer one of the 25 sub-metering areas has a weight of 0 and data from there is not used. On the other hand, the weights of ρ7, ρ8, ρ9, ρ12, ρ14, ρ17, ρ18, and ρ19 are halved. This means that the weighting is halved for a one-round region surrounding the center. ρ13 is the central region, and 1 is weighted here. When weighting as described above is performed, the portion of (Expression 6) in the second term on the right side is subjected to light metering in the central portion regardless of the luminance value in each sub metering area.
[0043]
It should be particularly noted in the present invention that (Equation 5) takes into account both (Equation 2) of the first term on the right side and (Equation 6) of the second term.
For example, when attention is paid to only one sub-photometry area, it may appear twice instead of appearing only once in (Equation 5). Specifically, for data in a sub-photometry area where ρj is not 0 in the second term on the right side (equation 6), that is, an area given 1/2 or 1 as a weight, A constant weight has already been given by performing the calculation based on the setting basis that the order of the luminance level is given in Equation 2), and which sub-photometry area corresponds to the second term on the right side. This means that weighting according to (position) is made.
[0044]
More specifically, assuming that the area S (12) is D (4), it is the fourth data from the darkest in (Formula 2) of the first term on the right side of (Formula 5). Is a sub-photometric value corresponding to the darkest part, and the sub-target value at that time is processed as F1, normalized by F1, and its weighting coefficient is 1. .
On the other hand, in (Expression 6) in the second term on the right side of (Expression 5), the target value is an intermediate value of F3 because it is an area that surrounds the center, and is normalized by this F3. Thus, the weighting coefficient is ½.
[0045]
Data in the same area that are processed based on different grounds are added with different weights, and the result is a comprehensive judgment that reflects the meaning of bright or dark TS. It has become.
That is, in the embodiment based on (Equation 5), both the area-wise (sub-photometric area position) judgment and the judgment corresponding to the order of the luminance level are taken into consideration at the same time, which is one limitation of the present invention. This is a very characteristic point. Also in terms of effect, it is particularly excellent in that appropriate exposure control that takes into account both the element relating to the positional distribution of the sub-photometry area and the level of the luminance level can be realized.
[0046]
As a modification of the above-described second embodiment, it is not necessarily limited to only the above two setting grounds, and it may be possible to further add another setting ground section.
That is, even when there are a lot of terms processed by the difference from the sub target value or when it is desired to add various items to be considered, these terms can be simply added to form the terms. Information on (item) can be reflected in the TS. The extent to which the term (item) is reflected can be arbitrarily set by processing the weighting coefficient. Therefore, the third and fourth terms can be added additionally. In the above-described example, description has been made mainly on processing of luminance output. However, since information obtained from a video signal can be obtained not only luminance information but also data relating to color information (for example, chromaticity value), It is also a preferred embodiment to add a term in which different target values and weighting are performed depending on how many chromaticity values are extracted even from data extracted from the same area.
[0047]
Next, regarding the setting of the sub target value for the sub photometric value, not only simply following the order in the luminance level but also considering the distribution of the luminance, a plurality of sub target values prepared in advance are prepared. A third embodiment in which selection is made from among the candidates will be described.
In this embodiment, the value Ak defined by (Equation 7) is used.
[Expression 7]

In this (Equation 7), k is an integer of 0 to 5.
The denominator of (Expression 7) is 5, and the numerator of the first term is k × MAX {S (N)}, and the second term is (5-k) × MIN {S (N)}.
The meaning of this (Equation 7) will be described with reference to FIG. 3. When 0 or 5 is substituted for k, the value of MIN {S (N)} or MAX {S (N)} is used as it is. Has been. Further, when k takes a value between 1 and 4 in the meantime, it takes any value as if the portion between A5 and A0, which are just MAX and MIN, is divided into five equal parts.
[0048]
The reason for using Ak as described above is to enable the case-by-case processing using αN, K which is a coefficient in the following (Equation 8) for calculating TS.
For a certain area N, the sub-photometric value S (N) always exists as a value between MAX and MIN. The sub-photometric value S (N) has a shape corresponding to which of the level range divided into five as shown in FIG. 3, that is, S (N) is between A0 and A1, or A1 to A2. It is classified in the form of between, between A2 and A3, between A3 and A4, and between A4 and A5. (Equation 8) using such Ak is as follows.
[Equation 8]

Looking at this (Equation 8) analytically, there are two coefficients for the value obtained by subtracting the sub target value FK from the sub photometric value S (N) and using FK as the denominator, that is, the coefficient αN, K And a weighting coefficient ρK (for weighting according to brightness), K is prepared from 1 to 5, and for this Σ, N = 1 corresponding to 25 areas It means that Σ of ~ 25 is taken.
The definition of the coefficient αN, K is 1 when S (N) is between Ak-1 and Ak, and 0 otherwise.
[0049]
As the processing at the end point, S (N) = A5 is also set to 1, but the idea is that whether α is 1 or 0 is divided into cases as described above, so that FIG. Corresponding to which area (level range) the value of S (N) belongs to. That is, the calculation is performed in such a way that α is 1 if it is in a certain K-th stage and 0 if it is not, so that A4 to A5 at the top of the five-stage classification is consequently obtained. A sub-target value of F5 is given to the sub-photometric value in between. If there is a sub metering value between the middle A2 and A3, a sub target value of F3 is given. That is, the sub target value for each S (N) classifies the luminance distribution of the subject into five levels, and F1 to F5 are assigned according to the brightness.
[0050]
In the second embodiment described above, the sub-photometry values are rearranged in the order of brightness, and are divided into five parts and assigned F1 to F5. Even when there are 10 bright places and the rest is dark, the processing is performed unconditionally in increments of 5. However, in the third embodiment, processing reflecting the luminance distribution state is performed. Yes, more appropriate exposure control can be performed.
[0051]
Next, a fourth embodiment of the present invention will be described below. In the fourth embodiment, an appropriate sub target value is selected from the sub target value candidates set in advance in the third embodiment described above. Is different from that calculated by calculation.
An arithmetic expression for obtaining the optimum sub target value in this case is the following (Equation 9).
[Equation 9]

M (N) in (Equation 9) corresponds to the sub-target value for S (N) described in the first embodiment.
M (N) in this case is directly calculated by the proviso expression of (Equation 9). In this proviso equation, the calculation is performed using MAX {S (N)}. The meaning of this equation can be easily understood with reference to FIG. In the above description, the values of F are F1 to F5, but F0 and F6 are set as the values of F in FIG. However, the symbol (value) F˜ is defined by the above-described (Equation 1), and by substituting 0, 6 into K in this equation, these F0, F6 are obtained. This corresponds to 15% and 105% as the video signal level, and is set as a representative of a considerably dark value and a considerably light value.
[0052]
In the above, what value is made to correspond is determined according to the design circumstances. For example, although the above-described F1 is applied in place of F0 and the above-described F5 is applied in place of F6, the photometry system operates. However, the above-described F0 and F6 are more suitable here. It can be expected to obtain characteristics.
The setting of M (N) in the proviso of (Equation 9) is the MAX of the value of S (N) that is now focused on among the various values of the sub-photometric value S (N) as shown in FIG. , MIN so that the target value M (N) to be given this time for F6 in the bright part and F0 in the dark part considered as the control target values is the ratio between F6 and F0. Means.
[0053]
Of course, depending on the brightness of the subject, the idea of bright target values as bright target values and dark target values as dark target values is the basis of the present invention. It is ideal to set a corresponding target value, and the fourth embodiment can be considered.
Here, once again confirming, the target value M (N) is not selected as one of the candidate values of the target value prepared in advance, but according to the level distribution of the sub-photometric value at that time by calculation. Is given.
[0054]
Next, a fifth embodiment of the present invention will be described below. This embodiment does not require different characteristics for the setting of the sub target value and the calculation method of the sub photometric value, and these can be applied to those described in the above embodiments. The sub-photometric value detection unit is characterized.
FIG. 5 is a block diagram showing a fifth embodiment of the present invention. In this embodiment, an image sensor that photoelectrically converts and outputs subject light via an optical system, and a digital video signal obtained by A / D converting the output signal of the image sensor are provided with a plurality of screens related to the video signal. DCT calculation means for obtaining a DCT coefficient by performing DCT calculation for each block when the block is divided into blocks, and applying the block as the sub-photometry area.
[0055]
The embodiment of FIG. 5 will be described by comparison with the embodiment of FIG. Corresponding parts to FIG. 1 are given the same reference numerals. In FIG. 1, a circuit unit called integration by area of the block 8 is provided, but the output data from the preprocess 4 is integrated by sub-photometry area in this circuit unit. On the other hand, in the configuration of FIG. 5, there is no circuit unit for performing this integration. Instead, a DCT calculation unit 61 is provided inside the block 6 so that the recording process circuit portion is depicted in detail.
[0056]
In this DCT calculation unit 61, the amount of data supplied to the recording process unit circuit 6 is very large. If recording is performed as it is, the required capacity of the storage device becomes too large, which is uneconomical. Since there is a problem such as a long data recording time, information is compressed to deal with such a problem. The DCT operation (Discrete Cosine Transformation) is one of the techniques that have been widely used in recent years to compress still image information for the above-mentioned purpose.
In this DCT operation, one wide image region (pixel region) to be compressed is divided into a plurality of sub-blocks, and internal data is converted into a frequency region for each sub-block. The amount of information is compressed by performing a process of thinning out unnecessary data for the data converted into the frequency domain. By conversion to the frequency domain, a low frequency domain, that is, a coefficient with little or no spatial change (DC coefficient) that is close to DC or DC is always calculated for each block.
[0057]
The above DC coefficient corresponds to the average value of luminance in the block. Therefore, the DC coefficient has a meaning that can be used as the sub-photometric value in the block, and this point is used in the fifth embodiment. That is, the division into sub-blocks for performing DCT calculation corresponds to the division into sub-photometry areas, and the DC coefficient for each sub-block corresponds to the sub-photometry values, and is equivalent to the sub-photometry area. A sub target value is set for each meaningful sub-block, and exposure control is performed using the features of the present invention.
[0058]
FIG. 6 is a schematic diagram showing a screen division state in the embodiment of FIG. FIG. 6 corresponds to the screen described in FIG. 2 and is composed of 768 horizontal pixels × 480 vertical pixels. In this embodiment, it is planned to use a screen (imaging device) having such a configuration, but an applicable screen (imaging device) is not limited to this.
FIG. 7 is a schematic diagram showing a state of a screen by another image sensor applicable to the embodiment of FIG. 7 is composed of horizontal 640 × vertical 480 pixels.
How to set the DCT block is a matter of design choice, but the most commonly used one is a block consisting of 8 pixels by 8 pixels and 8 pixels by 8 pixels. To divide. In this case, the number of areas in the image sensor of FIG. 6 is 5760 blocks having a block number of 96 × 60, and the number of areas is 4800 blocks of 80 × 60 blocks in the image sensor of FIG. For each block, an average value of luminance signals corresponding to the sub-photometric values is obtained as a DC coefficient.
[0059]
The number of these blocks is much larger than the 25 sub-metering areas described above, but the present invention originally intends to perform fine exposure control that reflects the situation of each partial area. Therefore, ideal control according to the spirit of the inventive idea can be achieved by dividing the sub-photometry area (block) as finely as possible within the capability of the arithmetic function unit. On the contrary, if the sub-metering area is too rough (large), there may be a boundary between areas that cannot be regarded as one area of the subject. For example, even if a photometric value with the same intermediate value is detected, there are actually a subject with intermediate brightness, and there are half of the bright and dark subjects, resulting in an intermediate The meaning of this phenomenon is different from the case where a typical value is detected. The basic idea of the present invention is to apply various photometric target values and control methods on the premise that the photometric values are obtained such that each place is bright, dark or intermediate. For this reason, it is possible to expect a preferable result rather than setting the sub-photometry area to be divided into many (finely) as described above.
[0060]
Except for the fifth embodiment, the case where the sub-photometry area is 25 has been described for convenience of explanation. However, it can be said that setting at least this level is sufficient to realize the preferred exposure control expected in the present invention. Further, when the sub-photometry area is not divided and set too much, the burden of various calculation function units is reduced, so that an advantage that a simple and inexpensive device as a whole can be realized cannot be overlooked.
Therefore, in the fifth embodiment, it may be possible to simplify the configuration by configuring the result of performing the addition processing for several blocks in advance so as to handle the result as each sub-photometric value. That is, it is possible to adopt a configuration in which one block of DCT is made to correspond as one sub-photometry area, or a configuration in which a plurality of blocks of DCT are made to correspond to one sub-photometry area. A block “block addition” indicated by a broken line in the block 9 of FIG. 5 is a functional block for the addition processing applied in the latter case.
[0061]
In the configuration in which the output from the preprocess is immediately and completely integrated as in the block 8 of FIG. 1, it is difficult to realize unless the data processing speed is sufficiently high. If the processing is performed on the result value after a certain amount of processing is performed, this calculation processing can be performed in the microcomputer. Accordingly, by adopting such a configuration, for example, the processing using 25 areas as in the first embodiment can use the DC coefficient of the DCT calculation without providing a separate integration circuit for each area. It is possible to realize the same processing.
[0062]
Next, a sixth embodiment of the present invention will be described below. In this embodiment, the control target value is set by the following (Equation 10).
[Expression 10]

The sixth embodiment is different from the first embodiment in that the coefficient βK, i is further multiplied. As can be understood from the proviso in (Equation 10), K = 1 to 4, that is, the coefficient βK, i is any for the terms relating to the darkest to 20th data (D (1) to D (20)). It has no influence. It has an effect only when K = 5 and only when D (20 + i) ≧ F5. According to (Equation 1), F5 = 2,592,000 so that it may be described as such, but for simplicity of description, it is described as above. The numerical value 3,456,000 is the maximum value that D (N) can take as described above. Now, the sub target value for D (20 + i) is F = 5 because K = 5. Accordingly, if the luminance distribution of the subject is within an appropriate range, the result of the control will be close to D (20 + i) = F5, or if D (20 + i) <F5 and the control is stable, the brightest category This means that the subject is also reproduced as a sufficiently low (not too bright) level signal, so there is no problem. However, in the case of D (20 + i)> F5, the control is stable in spite of causing the result of “overexposure”, so this becomes “underexposure” in other terms. It suggests that something exists.
Assuming that such other term is a low luminance part, eventually “the low luminance part is underexposed even for a low target level, and the high luminance part D (20 + i) is exposed even for a high target level F5. Since it is “over”, there is a possibility that so-called blackout or whiteout of the image may occur.
[0063]
Therefore, it is required to save the so-called blackout and whiteout. The control that can be taken in such a case is to abandon the reproduction of one of the low luminance part and the high luminance part and save only the other.
The coefficient βK, i takes the following values (Table 1) according to the value of D for the five high brightness terms with K = 5.
[Table 1]

For this reason, “when the high-luminance part is less than or equal to the target value F5, control equivalent to that of the first embodiment is performed, but as F5 becomes larger, the degree of contribution to the control of the term of the high-luminance part By suppressing this, the faithful reproduction of the high luminance portion is abandoned. Thereby, reproducibility of other portions can be ensured.
[0064]
In the above, the action of “suppressing the degree of contribution to the control” is “when the sub-photometric value deviates from the predetermined level range, in one limited aspect (10) of the imaging apparatus of the present invention. Corresponds to “suppress the calculation result value of the sub target value” in the feature point of “including means for suppressing the calculation result value of the sub photometric value and the sub target value set for the sub metering value”. .
[0065]
The coefficient βK, i = 0 can also occur. In this case, “invalidation” may be included in the concept of “suppression”.
Further, in the above example (Table 1), βK, i changes continuously (increase and decrease gradually) with respect to the value of D (20 + i), but this is a smooth and natural control. In addition, although it has the meaning of achieving both reproduction of high and low luminance parts to the limit, βK, i is not limited to this, and may take a value that changes appropriately and discontinuously.
Furthermore, in the above-described example, “suppression” is performed for the high luminance part, but it is needless to say that it may be performed for the low luminance part. Alternatively, it may be applied to other conditions, or may be applied simultaneously to a plurality of conditions as required.
Furthermore, in the above-described example, the first embodiment is used as a basis and is additionally multiplied by the coefficient βK, i. However, the basis configuration can be arbitrarily selected, and the implementation method (form) is also arbitrary. .
[0066]
In each of the embodiments described above, the number of pixels on one screen has been described as, for example, 768 × 480. However, when this is the number of pixels on a so-called one-frame screen in an NTSC 2: 1 interlaced video signal. In many cases, various signal processing in an actual imaging apparatus is executed in units of so-called one-field screens. In this way, when processing is performed in units of one field screen, each target value may be set as 768 × 240, assuming that the number of pixels in one screen is half the number of pixels in the vertical direction compared to the above.
[0067]
The above example is an electronic still camera using a digital memory, but the present invention can be applied to various photographing apparatuses including a video camera recorder, a silver salt still camera, and a silver salt cinema camera.
[0068]
The configurations of the present invention described above and various limited aspects thereof, the problems to be solved by them, and the effects as the invention will be summarized below.
[0069]
(1) To obtain a sub-photometric value corresponding to the luminance of the subject to be photographed for each photometric area, with each region obtained by dividing the whole or part of the photographing screen divided into a plurality of regions. Sub-photometric means,
  Each sub metering value output from the sub metering means should be reached separatelyControl target valueSub target value setting means for setting a sub metering target value;
  Between each sub target value set by the sub target value setting means and each sub photometric value corresponding thereto.Find each deviation that is a quantitative (multi-valued) difference,A calculating means for calculating a sum of deviations to obtain an exposure control amount relating to the subject to be photographed;
  Based on the exposure control amount obtained by the calculation means, the exposure related to the photographing is calculated.So that the deviation is smaller overallExposure control means to control;
An imaging apparatus comprising:
[0070]
In the prior art prior to the invention of (1), it has been difficult to determine an optimum exposure value that takes into account the different brightness of each part in the screen to be imaged.
The invention of the above (1) obtains a suitable exposure for various subject scenes including a backlight scene etc. with a simple configuration without including complicated and expensive components such as an automatic tracking device and a fuzzy inference circuit. It is an object of the present invention to provide an imaging device that can handle the above.
[0071]
According to the invention of (1) above, since a separate target value is given to each sub-photometric value, a bright target value is set for a bright part, a dark target value is set for a dark part, and an intermediate value is set for an intermediate luminance part. Target or average target values are respectively given, and exposure in consideration of the luminance range of the imaging system can be obtained.
[0072]
In the invention of (1) above, the luminance range should be called a luminance reproduction region in other words, and as described above, the imaging system cannot reproduce everything from a bright place to a dark place. When it is attempted to perform exposure control as appropriate as possible within the reproducible range, it is desirable to perform exposure control as in the above invention (1).
[0073]
  (2) The calculation means normalizes those levels for each deviation between each sub-photometric value and each corresponding sub-target value.DoThe imaging apparatus according to (1) above, comprising level normalizing means.
[0074]
In the technology before the invention of the above (2), no particular consideration has been given to how the influence of the bright part and the dark part of the subject are related and reflected in the exposure control.
[0075]
According to the invention of (2) above, in addition to the effect of the invention of (1) above, in particular, since the information amount of the bright part and the information quantity of the dark part of the subject are treated equally, There is an effect that there is no excessive influence.
[0076]
In the invention of (2) above, the level standardization is performed by the level normalization means. This is a concept that should be distinguished from the above-mentioned “standardization related to the area”, and this is also the standardization related to the level after the standardization related to the area in the present embodiment. It will be understood from the fact that In other words, the standardization related to the area only guarantees that the same value can be obtained from each area when there is a subject with the same brightness. With respect to a certain scene (an image in which a bright subject and a dark subject are mixed), it is completely impossible to adjust how the influence of the bright part and the influence of the dark part contribute to the adjustment of exposure.
In conventional operations such as simple weighted addition and subtraction, where normalization or only difference is taken and normalization is not performed, the ratio of the output from the bright part is high as a numerical value, and the influence of this bright part is dominant It tends to be a neighbor. Level normalization is effective in suppressing such a tendency that the influence of bright parts becomes dominant.
[0077]
(3) The calculation means includes a level normalization means for normalizing levels of the deviations between the photometric values and the corresponding sub target values, and the level normalization means. The imaging apparatus according to (1), further comprising: a weighting unit that performs predetermined weighting on each normalized value.
[0078]
According to the invention of (3) above, in addition to the effect of the invention of (1) above, it is possible to perform intensive exposure control especially regarding the luminance distribution of the subject.
[0079]
  (4) The exposure control means performs feedback control by changing a parameter relating to exposure so that the photometric value converges to a predetermined value. (1), (2) or (3) ) Imaging device.
[0080]
According to the invention of (4), in addition to the effects of the invention of (1), (2) or (3), in particular, exposure control can be performed very simply and stably.
[0081]
  (5) The sub target value setting means is configured to form an order according to the magnitude of each sub photometric value and set each sub target value so as to correspond to the order. The imaging device according to (1), (2), (3) or (4).
[0082]
According to the invention of (5), in addition to the effects of the invention of (1), (2), (3) or (4), in particular, calculation for photometry or exposure control becomes very simple. . Since the order is simply rearranging the order according to the magnitude relationship, the above operation is greatly simplified by processing based on the order.
[0083]
  (6) The sub target value setting means sets a plurality of sub target values based on different setting grounds as the sub target values to be set corresponding to the sub photometric values. The above (1), (2), characterized by comprising means for performing a different calculation for each of the plurality of sub target values for each of the sub-photometric values and obtaining the photometric value from the result of the different calculation. ), (3) or (4).
[0084]
According to the invention of (6) above, in addition to the effects of the invention of (1), (2), (3) or (4), in particular, both of the luminance distribution on the screen and the order of luminance. Makes it possible to perform delicate and advanced exposure control that takes into account other factors relating to photometry in an arbitrary distribution.
[0085]
(7) The sub target value setting means is uniquely selected from a group of candidate values that can be set as sub target values corresponding to the sub photometry values according to the order formed by the sub photometry means. The imaging apparatus according to (5) above, including means for selecting a predetermined value as a sub target value.
[0086]
According to the invention of (7) above, in addition to the effect of the invention of (5) above, in particular, it is possible to very easily perform processing relating to exposure control.
[0087]
If the target value prepared in advance is selected as described above, the candidate values prepared in advance are fixedly held in, for example, EE / PROM. The fixed values are compared by a separate means. If the configuration is such that it can be easily rewritten, it is easy to give various variations of the control, and the control system has a simple configuration. This is a great advantage particularly when the present invention is configured systematically.
[0088]
(8) The sub target value setting means performs a calculation considering the level distribution of each sub target value according to the order formed by the sub photometry means, and sets a group of candidate values that can be set as sub target values. The image pickup apparatus according to (5), further including means for selecting a predetermined value from among the sub target values.
[0089]
According to the invention of (7), in addition to the effect of the invention of (5), it is possible to perform delicate exposure control considering both the order of brightness and the brightness distribution on the screen. Become.
[0090]
(9) The sub target value setting means includes means for setting a sub target value by performing an operation in consideration of a distribution of levels of each sub target value in accordance with the order formed by the sub photometric means. The imaging apparatus according to (5) above, which is characterized.
[0091]
According to the invention of (9), in addition to the effect of the invention of (5), it is possible to perform delicate exposure control considering both the order of brightness and the brightness distribution on the screen. Become.
[0092]
(10) The photometry calculating means includes means for suppressing, when the sub photometric value deviates from a predetermined level range, a calculation result value of the sub photometric value and a sub target value set for the sub photometric value. The imaging apparatus according to (5), characterized in that:
[0093]
According to the invention of (10) above, in addition to the effect of the invention of (5) above, in particular, only when the luminance difference between the high luminance part and the low luminance part on the screen is too large, It becomes possible to perform exposure control giving priority to reproducibility.
[0094]
  (11) An image sensor that photoelectrically converts and outputs subject light via an optical system; a digital video signal obtained by A / D converting the output signal of the image sensor; and a screen related to the video signal in a plurality of blocks DCT calculation means for obtaining a DCT coefficient by performing DCT calculation for each block when divided, and applying the block as the sub-photometry area (1), (2 ), (3), (4), (5), (6), (7), (8), (9) or (10).
[0095]
According to the invention of (11) above, (1), (2), (3), (4), (5), (6), (7), (8), (9) or (10) In addition to the effects of the present invention, in particular, when the screen is divided into a plurality of blocks that are essential for performing DCT calculation, which is one calculation method of data compression that is becoming common in this type of apparatus. By using each block, it is possible to perform exposure control with a simple configuration without separately setting sub-block division settings.
[0096]
【The invention's effect】
In the screen, a bright target value is given to a bright part, a dark target value is given to a dark part, and an intermediate to average target value is given to an intermediate brightness part. Suitable exposure considering the above can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a digital electronic still camera as an embodiment of an imaging apparatus according to the present invention.
FIG. 2 virtually rearranges each sub-photometry area according to the allocation status of the sub-photometry area with respect to the photoelectric conversion surface (effective imaging area) of the image sensor and the order of the sub-photometry values corresponding to each sub-photometry area. It is a schematic diagram which shows the state which carried out.
FIG. 3 is a diagram for explaining an arithmetic expression (Expression 7) in the embodiment of the present invention;
FIG. 4 is a diagram for explaining an arithmetic expression (Equation 9) in the embodiment of the present invention;
FIG. 5 is a block diagram showing a fifth embodiment of the present invention.
6 is a schematic diagram showing a screen division state in the embodiment of FIG. 5. FIG.
7 is a schematic diagram showing a state of a screen by another imaging device applicable to the embodiment of FIG.
[Explanation of symbols]
1 Imaging optics
2 Aperture
3 Image sensor
4 Preprocess circuit
5 Imaging process circuit
6 Recording process circuit
61 DCT operation part
7 Memory card interface
8 Area integration circuit
9 Microcomputer
91 Sub target value setting process
92 Photometric value calculation processing
93 Exposure control judgment process
94 block addition
10 Iris driver
11 Imager driver

Claims (11)

Sub-photometry for obtaining sub-photometry values corresponding to the brightness of the subject to be photographed for each photometry area, with each region obtained by dividing the whole or part of the photographing screen divided into a plurality of regions. Means,
Sub target value setting means for setting a sub photometric target value, which is a control target value to be reached separately for each sub photometric value output from the sub photometric means,
Deviations that are quantitative (multi-valued) differences between each sub target value set by the sub target value setting means and each sub photometric value corresponding to the sub target value are calculated, and the sum of the deviations is calculated to Arithmetic means for obtaining an exposure control amount relating to a subject to be photographed;
Exposure control means for controlling the exposure related to the photographing based on the exposure control amount obtained by the computing means so that the deviation is smaller overall ;
An imaging apparatus comprising:   The arithmetic means comprises level normalization means for normalizing the levels of the deviations between the sub-photometric values and the corresponding sub-target values. The imaging device according to claim 1.   The arithmetic means is standardized by level normalizing means for normalizing those levels between each photometric value and each sub target value corresponding thereto, and the level normalizing means. The imaging apparatus according to claim 1, further comprising weighting means for performing predetermined weighting on each value.   The imaging apparatus according to claim 1, wherein the exposure control means performs feedback control by changing a parameter relating to exposure so that the photometric value converges to a predetermined value.   2. The sub target value setting means is configured to form an order according to the magnitude of each sub photometric value and set each sub target value so as to correspond to the order. The imaging apparatus according to 2, 3, or 4.   The sub target value setting means sets a plurality of sub target values based on different setting grounds as the sub target values to be set corresponding to the sub photometric values, and the calculation means The means for calculating a photometric value for each of the plurality of sub-target values and obtaining the photometric value from the result of the different calculation is provided. The imaging device described.   The sub target value setting means is a predetermined value uniquely selected from a group of candidate values that can be set as a sub target value corresponding to each sub photometry value according to the order formed by each sub photometry means. The imaging apparatus according to claim 5, further comprising means for selecting as a sub target value.   The sub target value setting means performs a calculation considering the distribution of levels of each sub target value in accordance with the order formed by the sub photometry means, and selects a predetermined value from a group of candidate values that can be set as the sub target value The image pickup apparatus according to claim 5, further comprising means for selecting a value for the sub target value.   The sub target value setting means includes means for setting a sub target value by performing an operation in consideration of a distribution of levels of each sub target value in accordance with the order formed by the sub photometric means. The imaging device according to claim 5.   The photometric calculation means includes means for suppressing, when the sub-photometric value deviates from a predetermined level range, a calculation result value of the sub-photometric value and a sub target value set for the sub-photometric value. The imaging device according to claim 5.   When an image sensor that photoelectrically converts and outputs subject light via the optical system and a digital video signal obtained by A / D converting the output signal of the image sensor into a plurality of blocks DCT calculation means for obtaining a DCT coefficient by performing a DCT calculation for each of the blocks, wherein the block is applied as the sub-photometry area. The imaging device according to 5, 6, 7, 8, 9 or 10.

Images