JP4155043B2

JP4155043B2 - Video signal correction circuit

Info

Publication number: JP4155043B2
Application number: JP2003026737A
Authority: JP
Inventors: 敏行加藤; 正弘竹島
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2003-02-04
Filing date: 2003-02-04
Publication date: 2008-09-24
Anticipated expiration: 2023-02-04
Also published as: JP2004241882A

Description

【０００１】
【発明の属する技術分野】
本発明はヒストグラム変換型階調補正回路および色飽和度補正回路の制御に関し、特に映像信号の肌色部分の輝度分布に応じてヒストグラム変換型階調補正回路および色飽和度補正回路を制御する回路および映像信号補正回路に関する。
【０００２】
【従来の技術】
近年、テレビジョンの大画面化は目ざましいものがあり、そのため画質に関する要求はますます高まりつつある。とりわけ人間の目は人の肌の再現に関しては敏感であり、人の肌の階調が画質に与える影響は大なるものがある。
【０００３】
図７は従来の肌色輝度向上回路のブロック構成図を示す（例えば特許文献１）。映像信号補正回路制御装置は映像信号の色差信号から１フレーム中の肌色部分の面積を検出する肌色面積検出回路７０１と、映像信号の色差信号と輝度信号から１フレーム中の肌色部分の平均輝度レベルを検出する肌色平均輝度レベル検出回路７０２と、映像信号の輝度信号から１フレームの平均輝度レベルを検出する平均輝度レベル検出回路７０３と、前記肌色面積検出回路からの出力と前記肌色平均輝度レベル検出回路からの出力と前記平均輝度レベル検出回路からの出力を入力として１フレームの肌色部分の面積と１フレームの肌色部分の平均輝度レベルと１フレームの平均輝度レベルに応じたガンマ補正回路制御信号を作成するガンマ補正回路制御装置７０４と、前記ガンマ補正回路制御装置からの出力を入力としてガンマ補正回路制御信号に応じたガンマ補正を映像信号の輝度信号に掛けるガンマ補正回路７０５を備えた構成である。
【０００４】
以上のように構成された従来の肌色輝度向上回路においては、テレビジョンセットのＣＲＴのビーム量を調整するＡＣＬや映像信号の黒レベルを調整する黒伸長補正の副作用によって暗くくすんでしまった肌色の輝度レベルを、映像信号の平均輝度レベルと肌色部分の平均輝度レベルに応じて向上させる。
【０００５】
【特許文献１】
特開平７−２８８８３９号公報
【０００６】
【発明が解決しようとする課題】
しかしながら前記のような構成では、映像信号の平均輝度レベルと肌色部分の平均輝度レベルで補正を行うだけであり、肌色部分の輝度分布が高輝度側と低輝度側の両側に大きく分かれている場合と中輝度に集中している場合にはともに肌色部分の平均輝度が中輝度域となることから双方の区別が付かず、また肌色部分の輝度レベルを向上すると同時に肌色部分の階調性を損なうという不具合があるなど、肌色の輝度分布に応じた適切な映像信号補正を掛けることができなかった。
【０００７】
本発明はかかる点に鑑み、視聴者が映像の状態に応じた最適な映像信号補正状態でのテレビジョンの視聴を可能とする映像信号補正回路を提供することを目的とする。
【０００８】
【課題を解決するための手段】
映像信号の色差信号と輝度信号から１フレーム中の肌色部分の輝度分布を検出する肌色輝度分布検出回路と、映像信号の輝度信号から１フレーム中の輝度分布を検出する輝度分布検出回路と、前記肌色輝度分布検出回路からの出力と前記輝度分布検出回路からの出力を入力として１フレーム中の映像信号の肌色部分の輝度分布と１フレーム中の輝度分布に応じたヒストグラム変換型階調補正回路制御信号を作成するヒストグラム変換型階調補正回路制御装置と、前記ヒストグラム変換型階調補正回路制御装置からの出力を入力としてヒストグラム変換型階調補正回路制御信号に応じた階調補正を輝度信号に掛けるヒストグラム変換型階調補正回路と、前記ヒストグラム変換型階調補正回路制御装置からの出力を入力としてヒストグラム変換型階調補正回路制御信号に応じた色飽和度補正回路制御信号を作成する色飽和度補正回路制御装置と、前記色飽和度補正回路制御装置からの出力と輝度信号を入力として色飽和度補正回路制御信号に応じた色飽和度補正を色差信号に掛ける色飽和度補正回路を備えた構成としている。
【０００９】
本発明は前記した構成により、映像信号の色差信号と輝度信号から１フレーム中の肌色部分の輝度分布を検出する肌色輝度分布検出回路の出力と映像信号の輝度信号から１フレーム中の輝度分布を検出する輝度分布検出回路の出力の前者または両者からヒストグラム変換型階調補正回路制御装置において映像状態を算出し、ヒストグラム変換型階調補正回路制御装置においてこの映像状態に応じたヒストグラム変換型階調補正回路制御信号を作成し、ヒストグラム変換型階調補正回路制御装置からの出力信号により映像信号の状態に応じた最適なヒストグラム変換型階調補正を行い、また場合によって色飽和度補正回路制御装置においてヒストグラム変換型階調補正回路制御装置からの出力信号に応じた色飽和度補正回路制御信号を作成し、色飽和度補正回路制御装置からの出力信号によりヒストグラム変換型階調補正回路制御装置からの出力信号に応じた最適な色飽和度補正を行う。
【００１０】
【発明の実施の形態】
（実施の形態１）
図１は本発明の一実施例における映像信号補正回路を示す。図１において、１０１は映像信号から１フレーム中の肌色部分の輝度分布を検出する肌色輝度分布検出回路であり、１０２は前記肌色輝度分布検出回路からの出力を入力として１フレームの肌色輝度分布に応じたヒストグラム変換型階調補正回路制御信号を作成するヒストグラム変換型階調補正回路制御装置であり、１０３は前記ヒストグラム変換型階調補正回路制御装置からの出力を入力としてヒストグラム変換型階調補正回路制御信号に応じた階調補正を輝度信号に掛けるヒストグラム変換型階調補正回路である。
【００１１】
以上のように構成された映像信号補正回路について以下その動作説明を行う。まず、図１における肌色輝度分布検出回路１０１において映像信号から１フレーム中の肌色部分の輝度分布を検出し、検出した結果を電圧に変換する。なお、検出回路の出力は電圧だけでなく電流でも良いことはいうまでもない。検出された肌色部分の輝度分布を図１におけるヒストグラム変換型階調補正回路制御装置１０２に入力し１フレームの肌色輝度分布に応じたヒストグラム変換型階調補正回路制御信号を作成し電圧または電流に変換して出力する。出力されたヒストグラム変換型階調補正回路制御信号はヒストグラム変換型階調補正回路１０３に入力され、ヒストグラム変換型階調補正回路制御信号に応じたヒストグラム変換型階調補正を映像信号の輝度信号に掛ける。
【００１２】
以上のように本実施の形態１によれば１フレームの肌色部分の輝度分布を検出することで映像の肌色部分の輝度分布に応じた最適なヒストグラム変換型階調補正が可能となる。
【００１３】
（実施の形態２）
図２は本発明の一実施例における映像信号補正回路のブロック構成図を示す。図２において、上記実施の形態１と構成が異なる点は、肌色輝度分布検出回路１０１に加えて輝度分布検出回路２０６を備え、肌色輝度分布検出回路１０１の出力に加えて輝度分布検出回路２０６の出力をヒストグラム変換型階調補正回路制御装置２０２の入力とした構成としていることである。輝度分布検出回路２０６は輝度信号から１フレーム中の輝度分布を検出する。他の構成については実施の形態１と同様なので説明を省略する。
【００１４】
以上のように構成された映像信号補正回路について以下その動作説明を行う。まず、図２における肌色輝度分布検出回路１０１において映像信号から１フレーム中の肌色部分の輝度分布を検出し、検出した結果を電圧に変換する。なお、検出回路の出力は電圧だけでなく電流でも良いことはいうまでもない。また図２における輝度分布検出回路２０６において映像信号から１フレーム中の輝度分布を検出し、検出した結果を電圧または電流に変換する。検出された肌色部分の輝度分布と輝度分布を図２におけるヒストグラム変換型階調補正回路制御装置２０２に入力し１フレーム中の映像信号の肌色部分の輝度分布と１フレーム中の輝度分布に応じたヒストグラム変換型階調補正回路制御信号を作成し電圧または電流に変換して出力する。出力されたヒストグラム変換型階調補正回路制御信号はヒストグラム変換型階調補正回路１０３に入力され、ヒストグラム変換型階調補正回路制御信号に応じたヒストグラム変換型階調補正を映像信号の輝度信号に掛ける。
【００１５】
以上のように本実施の形態２によれば１フレーム中の映像信号の肌色部分の輝度分布と１フレーム中の輝度分布を検出することで映像の肌色部分の輝度分布と輝度分布に応じた最適なヒストグラム変換型階調補正が可能となる。
【００１６】
（実施の形態３）
図３は本発明の一実施例における映像信号補正回路のブロック構成図を示す。図３において、１０１は映像信号から１フレーム中の肌色部分の輝度分布を検出する肌色輝度分布検出回路であり、１０２は前記肌色輝度分布検出回路からの出力を入力として１フレームの肌色輝度分布に応じたヒストグラム変換型階調補正回路制御信号を作成するヒストグラム変換型階調補正回路制御装置であり、１０３は前記ヒストグラム変換型階調補正回路制御装置からの出力を入力としてヒストグラム変換型階調補正回路制御信号に応じた階調補正を輝度信号に掛けるヒストグラム変換型階調補正回路であり、３０４は前記ヒストグラム変換型階調補正回路制御装置からの出力を入力としてヒストグラム変換型階調補正回路制御信号に応じた色飽和度補正回路制御信号を作成する色飽和度補正回路制御装置であり、３０５は前記色飽和度補正回路制御装置からの出力と輝度信号を入力として色飽和度補正回路制御信号に応じた色飽和度補正を色差信号に掛ける色飽和度補正回路である。
【００１７】
以上のように構成された映像信号補正回路について以下その動作説明を行う。まず、図３における肌色輝度分布検出回路１０１において映像信号から１フレーム中の肌色部分の輝度分布を検出し、検出した結果を電圧に変換する。なお、検出回路の出力は電圧だけでなく電流でも良いことはいうまでもない。検出された肌色部分の輝度分布を図３におけるヒストグラム変換型階調補正回路制御装置１０２に入力し１フレームの肌色輝度分布に応じたヒストグラム変換型階調補正回路制御信号を作成し電圧または電流に変換して出力する。出力されたヒストグラム変換型階調補正回路制御信号はヒストグラム変換型階調補正回路１０３に入力され、ヒストグラム変換型階調補正回路制御信号に応じたヒストグラム変換型階調補正を映像信号の輝度信号に掛ける。また出力されたヒストグラム変換型階調補正回路制御信号は色飽和度補正回路制御装置３０４に入力され、ヒストグラム変換型階調補正回路制御信号に応じた色飽和度補正回路制御信号を作成し電圧または電流に変換して出力する。出力された色飽和度補正回路制御信号は色飽和度補正回路３０５に入力され、色飽和度補正回路制御信号に応じた色飽和度補正を映像信号の色差信号に掛ける。
【００１８】
以上のように本実施の形態３によれば１フレームの肌色部分の輝度分布を検出することで映像の肌色部分の輝度分布に応じた最適なヒストグラム変換型階調補正が可能となり、またそのヒストグラム変換型階調補正に応じた最適な色飽和度補正が可能となる。
【００１９】
（実施の形態４）
図４は本発明の一実施例における映像信号補正回路のブロック構成図を示す。図４において、上記実施の形態３と構成が異なる点は、肌色輝度分布検出回路１０１に加えて輝度分布検出回路６を備え、肌色輝度分布検出回路１の出力に加えて輝度分布検出回路６の出力をヒストグラム変換型階調補正回路制御装置の入力とした構成としていることである。輝度分布検出回路２０６は輝度信号から１フレーム中の輝度分布を検出する。他の構成については実施の形態３と同様なので説明を省略する。
【００２０】
以上のように構成された映像信号補正回路について以下その動作説明を行う。まず、図４における肌色輝度分布検出回路１０１において映像信号から１フレーム中の肌色部分の輝度分布を検出し、検出した結果を電圧に変換する。なお、検出回路の出力は電圧だけでなく電流でも良いことはいうまでもない。また図４における輝度分布検出回路２０６において映像信号から１フレーム中の輝度分布を検出し、検出した結果を電圧または電流に変換する。検出された肌色部分の輝度分布と輝度分布を図４におけるヒストグラム変換型階調補正回路制御装置２０２に入力し１フレーム中の映像信号の肌色部分の輝度分布と１フレーム中の輝度分布に応じたヒストグラム変換型階調補正回路制御信号を作成し電圧または電流に変換して出力する。出力されたヒストグラム変換型階調補正回路制御信号はヒストグラム変換型階調補正回路１０３に入力され、ヒストグラム変換型階調補正回路制御信号に応じたヒストグラム変換型階調補正を映像信号の輝度信号に掛ける。また出力されたヒストグラム変換型階調補正回路制御信号は色飽和度補正回路制御装置３０４に入力され、ヒストグラム変換型階調補正回路制御信号に応じた色飽和度補正回路制御信号を作成し電圧または電流に変換して出力する。出力された色飽和度補正回路制御信号は色飽和度補正回路３０５に入力され、色飽和度補正回路制御信号に応じた色飽和度補正を映像信号の色差信号に掛ける。
【００２１】
以上のように本実施の形態４によれば１フレーム中の映像信号の肌色部分の輝度分布と１フレーム中の輝度分布を検出することで映像の肌色部分の輝度分布と輝度分布に応じた最適なヒストグラム変換型階調補正が可能となり、またそのヒストグラム変換型階調補正に応じた最適な色飽和度補正が可能となる。
【００２２】
（実施の形態５）
図５は本発明の一実施例におけるヒストグラム変換型階調補正回路制御装置のブロック構成図を示す。本実施の形態においては、図８のように２つ以上に分割されたN個の分割輝度領域を有するヒストグラム変換型階調補正の場合を取り上げて説明する。
【００２３】
図５において、５０７は１フレーム中の輝度領域ｉより高輝度領域における肌色部分の輝度分布であるＰ［ｉ＋１］からＰ［Ｎ］を入力として前記１フレーム中の輝度領域ｉより高輝度領域における肌色部分の輝度分布Ｐ［ｉ＋１］からＰ［Ｎ］に応じてヒストグラム変換型階調補正傾きへ加える補正量を作成する傾き増加量演算回路であり、５０８は１フレーム中の前記輝度領域ｉより低輝度領域における肌色部分の輝度分布であるＰ［１］からＰ［ｉ−１］を入力として前記１フレーム中の前記輝度領域ｉより低輝度領域における肌色部分の輝度分布Ｐ［１］からＰ［ｉ−１］に応じてヒストグラム変換型階調補正基本傾きより減じる補正量を作成する傾き減少量演算回路であり、５０９は輝度領域ｉにおける映像信号に依存しないヒストグラム変換型階調補正基本傾きＢ［ｉ］と前記傾き増加量演算回路からの出力を入力とし演算結果を出力とする加算器であり、５１０は前記加算器の出力と前記傾き減少量演算回路からの出力を入力とし輝度領域ｉにおける肌色輝度分布適応ヒストグラム変換型階調補正傾きＧ［ｉ］を出力する減算器であり、５１１は全輝度領域における前記肌色輝度分布適応ヒストグラム変換型階調補正傾きを入力としてヒストグラム変換型階調補正回路制御信号を作成するヒストグラム変換型階調補正回路制御信号演算回路である。
また本発明の前記一実施の形態における映像信号補正回路は上記実施の形態１と同じであるので説明を省略する。
【００２４】
以上のように構成されたヒストグラム変換型階調補正回路制御装置について以下その動作説明を行う。
まず、輝度領域ｉにおける映像信号に依存しないヒストグラム変換型階調補正基本傾きＢ［ｉ］に対して、前記輝度領域ｉより高輝度領域における肌色部分の輝度分布Ｐ［ｉ＋１］からＰ［Ｎ］に応じて作成された傾き増加量演算回路５０７の出力を加え、前記輝度領域ｉより低輝度領域における肌色部分の輝度分布Ｐ［１］からＰ［ｉ−１］に応じて作成された傾き減少量演算回路５０８の出力を減じ、輝度領域ｉにおける肌色輝度分布適応ヒストグラム変換型階調補正傾きＧ［Ｉ］を作成し、これを電圧または電流に変換して出力する。なお、ヒストグラム変換型階調補正基本傾きＢ［１］に対する傾き減少量演算回路５０８の出力はゼロであり、ヒストグラム変換型階調補正基本傾きＢ［Ｎ］に対する傾き増加量演算回路５０７の出力はゼロであることは言うまでもない。
【００２５】
次に、出力された各輝度領域における肌色輝度分布適応ヒストグラム変換型階調補正傾きGはヒストグラム変換型階調補正回路制御信号演算回路へ入力され、各輝度領域における肌色輝度分布適応ヒストグラム変換型階調補正傾きに応じたヒストグラム変換型階調補正回路制御信号を作成し電圧または電流に変換して出力する。
【００２６】
ヒストグラム変換型階調補正回路制御装置以外の動作は上記実施の形態１と同じであるので説明を省略する。
【００２７】
以上のように本実施の形態５によれば１フレーム中の肌色部分の輝度分布を検出することで映像の肌色部分の輝度分布に応じた最適なヒストグラム変換型階調補正回路制御信号の作成を作成し、肌色部分の階調性を損なうことなく映像の肌色部分の輝度分布に応じた最適なヒストグラム変換型階調補正が可能となる。
【００２８】
（実施の形態６）
図６は本発明の一実施例におけるヒストグラム変換型階調補正回路制御装置のブロック構成図を示す。本実施の形態においては、図８のように２つ以上に分割されたN個の分割輝度領域を有するヒストグラム変換型階調補正の場合を取り上げて説明する。
【００２９】
図６において、上記実施の形態５のヒストグラム変換型階調補正回路制御装置と構成が異なる点は、１フレーム中の輝度分布を入力として１フレーム中の輝度分布に応じた輝度分布適応ヒストグラム変換型階調補正傾きＨ［ｉ］を作成する輝度分布適応ヒストグラム変換型階調補正傾き演算回路６１２を備え、上記実施の形態５における映像信号に依存しないヒストグラム変換型階調補正基本傾きＢ［ｉ］を置き換えたことである。
【００３０】
ヒストグラム変換型階調補正回路制御装置に関する他の構成については実施の形態５と同様なので説明を省略する。
【００３１】
また本発明の前記一実施例における映像信号補正回路は上記実施の形態２と同じであるので説明を省略する。
【００３２】
以上のように構成されたヒストグラム変換型階調補正回路制御装置について以下その動作説明を行う。
まず、１フレーム中の輝度分布を入力として１フレーム中の輝度分布に応じた輝度分布適応ヒストグラム変換型階調補正傾きＨ［ｉ］を作成する輝度分布適応ヒストグラム変換型階調補正傾き演算回路６１２において１フレーム中の輝度分布に応じた輝度分布適応ヒストグラム変換型階調補正傾きＨ［ｉ］を作成し電圧または電流に変換して出力する。
【００３３】
次に、輝度領域ｉにおける輝度分布適応ヒストグラム変換型階調補正傾きＨ［ｉ］に対して、前記輝度領域ｉより高輝度領域における肌色部分の輝度分布であるＰ［ｉ＋１］からＰ［Ｎ］に応じて作成された傾き増加量演算回路５０７の出力を加え、前記輝度領域ｉより低輝度領域における肌色部分の輝度分布であるｐ［１］からＰ［ｉ−１］に応じて作成された傾き減少量演算回路５０８の出力を減じ、輝度領域ｉにおける肌色輝度分布適応ヒストグラム変換型階調補正傾きＧ［ｉ］を作成し、これを電圧または電流に変換して出力する。なお、ヒストグラム変換型階調補正基本傾きＨ［１］に対する傾き減少量演算回路５０８の出力はゼロであり、ヒストグラム変換型階調補正基本傾きＨ［Ｎ］に対する傾き増加量演算回路５０７の出力はゼロであることは言うまでもない。
【００３４】
次に、出力された各輝度領域における肌色輝度分布適応ヒストグラム変換型階調補正傾きＧはヒストグラム変換型階調補正回路制御信号演算回路へ入力され、各輝度領域における肌色輝度分布適応ヒストグラム変換型階調補正傾きに応じたヒストグラム変換型階調補正回路制御信号を作成し電圧または電流に変換して出力する。
【００３５】
ヒストグラム変換型階調補正回路制御装置以外の動作は上記実施の形態２と同じであるので説明を省略する。
【００３６】
以上のように本実施の形態６によれば１フレーム中の肌色部分の輝度分布と１フレーム中の輝度分布を検出することで映像の肌色部分の輝度分布に応じた最適なヒストグラム変換型階調補正回路制御信号を作成し、肌色部分の階調性を損なうことなく映像の肌色部分の輝度分布に応じた最適なヒストグラム変換型階調補正が可能となる。
【００３７】
（実施の形態７）
本発明の一実施例におけるヒストグラム変換型階調補正回路制御装置の構成は上記実施の形態５と同じであるので説明を省略する。
【００３８】
本発明の前記一実施例における映像信号補正回路は上記実施の形態３と同じであるので説明を省略する。
【００３９】
ヒストグラム変換型階調補正回路制御装置の動作は上記実施の形態５と同じであるので説明を省略する。
【００４０】
ヒストグラム変換型階調補正回路制御装置以外の動作は上記実施の形態３と同じであるので説明を省略する。
【００４１】
以上のように本実施の形態７によれば１フレーム中の肌色部分の輝度分布を検出することで映像の肌色部分の輝度分布に応じた最適なヒストグラム変換型階調補正回路制御信号を作成し、肌色部分の階調性を損なうことなく映像の肌色部分の輝度分布に応じた最適なヒストグラム変換型階調補正が可能となり、またそのヒストグラム変換型階調補正に応じた最適な色飽和度補正が可能となる。
【００４２】
（実施の形態８）
本発明の一実施例におけるヒストグラム変換型階調補正回路制御装置の構成は上記実施の形態６と同じであるので説明を省略する。
【００４３】
本発明の前記一実施例における映像信号補正回路は上記実施の形態４と同じであるので説明を省略する。
ヒストグラム変換型階調補正回路制御装置の動作は上記実施の形態６と同じであるので説明を省略する。
【００４４】
ヒストグラム変換型階調補正回路制御装置以外の動作は上記実施の形態４と同じであるので説明を省略する。
【００４５】
以上のように本実施の形態８によれば１フレーム中の肌色部分の輝度分布と１フレーム中の輝度分布を検出することで映像の肌色部分の輝度分布に応じた最適なヒストグラム変換型階調補正回路制御信号を作成し、肌色部分の階調性を損なうことなく映像の肌色部分の輝度分布に応じた最適なヒストグラム変換型階調補正が可能となり、またそのヒストグラム変換型階調補正に応じた最適な色飽和度補正が可能となる。
【００４６】
【発明の効果】
以上のように本発明は、視聴者が映像信号の肌色部分の輝度分布と映像信号の輝度分布に応じた最適なヒストグラム変換型階調補正と色飽和度補正での視聴を可能とすることができ、その実用的効果は大きい。
【図面の簡単な説明】
【図１】本発明の第一の実施の形態および第五の実施の形態における映像信号補正回路のブロック構成図
【図２】本発明の第二の実施の形態および第六の実施の形態における映像信号補正回路のブロック構成図
【図３】本発明の第三の実施の形態および第七の実施の形態における映像信号補正回路のブロック構成図
【図４】本発明の第四の実施の形態および第八の実施の形態における映像信号補正回路のブロック構成図
【図５】本発明の第五の実施の形態および第七の実施の形態におけるヒストグラム変換型階調補正回路制御装置のブロック構成図
【図６】本発明の第六の実施の形態および第八の実施の形態におけるヒストグラム変換型階調補正回路制御装置のブロック構成図
【図７】従来の肌色輝度向上回路のブロック構成図
【図８】分割輝度領域の説明図
【符号の説明】
１０１肌色輝度分布検出回路
１０２、２０２ヒストグラム変換型階調補正回路制御装置
１０３ヒストグラム変換型階調補正回路
３０４色飽和度補正回路制御装置
３０５色飽和度補正回路
２０６輝度分布検出回路
５０７傾き増加量演算回路
５０８傾き減少量演算回路
５０９加算器
５１０減算器
５１１ヒストグラム変換型階調補正回路制御信号演算回路
５１２輝度分布適応ヒストグラム変換型階調補正傾き演算回路[0001]
BACKGROUND OF THE INVENTION
The present invention relates to control of a histogram conversion type tone correction circuit and a color saturation correction circuit, and more particularly, a circuit for controlling a histogram conversion type tone correction circuit and a color saturation correction circuit according to the luminance distribution of a flesh color portion of a video signal, and The present invention relates to a video signal correction circuit.
[0002]
[Prior art]
In recent years, there has been a remarkable increase in the screen size of televisions, and as a result, there has been an increasing demand for image quality. In particular, human eyes are sensitive to human skin reproduction, and the influence of human skin gradation on image quality is significant.
[0003]
FIG. 7 is a block diagram of a conventional flesh color brightness enhancement circuit (for example, Patent Document 1). The video signal correction circuit control device includes a flesh color area detection circuit 701 that detects the area of a flesh color portion in one frame from the color difference signal of the video signal, and an average luminance level of the flesh color portion in one frame from the color difference signal and luminance signal of the video signal. A flesh color average luminance level detection circuit 702, an average luminance level detection circuit 703 that detects an average luminance level of one frame from the luminance signal of the video signal, an output from the flesh color area detection circuit, and the flesh color average luminance level detection. Using the output from the circuit and the output from the average luminance level detection circuit as input, a gamma correction circuit control signal corresponding to the area of the skin color portion of one frame, the average luminance level of the skin color portion of one frame, and the average luminance level of one frame is obtained. A gamma correction circuit controller 704 to be created, and a gamma correction circuit using the output from the gamma correction circuit controller as an input Gamma adjustment according to your signal a configuration in which a gamma correction circuit 705 to be applied to the luminance signal of the video signal.
[0004]
In the conventional skin tone luminance enhancement circuit configured as described above, the skin tone that has become darker and darker due to the side effect of the ACL for adjusting the CRT beam amount of the television set and the black extension correction for adjusting the black level of the video signal. The luminance level is improved in accordance with the average luminance level of the video signal and the average luminance level of the skin color portion.
[0005]
[Patent Document 1]
JP-A-7-288839 [0006]
[Problems to be solved by the invention]
However, in the configuration as described above, correction is performed only with the average luminance level of the video signal and the average luminance level of the flesh-colored portion, and the luminance distribution of the flesh-colored portion is largely divided on both the high-luminance side and the low-luminance side. When the concentration is concentrated on the medium luminance, the average luminance of the flesh-colored part is in the medium-luminance range, making it impossible to distinguish between the two, and improving the luminance level of the flesh-colored part and at the same time impairing the gradation of the flesh-colored part For example, it was not possible to apply appropriate video signal correction according to the skin color luminance distribution.
[0007]
In view of the above, an object of the present invention is to provide a video signal correction circuit that enables a viewer to view a television in an optimal video signal correction state according to the video state.
[0008]
[Means for Solving the Problems]
A skin color luminance distribution detection circuit for detecting a luminance distribution of a flesh color portion in one frame from a color difference signal and a luminance signal of a video signal; a luminance distribution detection circuit for detecting a luminance distribution in one frame from a luminance signal of the video signal; Histogram conversion type tone correction circuit control corresponding to the luminance distribution of the skin color portion of the video signal in one frame and the luminance distribution in one frame with the output from the skin color luminance distribution detecting circuit and the output from the luminance distribution detecting circuit as inputs. A histogram conversion type tone correction circuit control device for generating a signal, and an output from the histogram conversion type tone correction circuit control device as an input, tone correction according to the histogram conversion type tone correction circuit control signal is made into a luminance signal. Multiplying histogram conversion type gradation correction circuit and histogram conversion type using the output from the histogram conversion type gradation correction circuit control device as input A color saturation correction circuit control device for creating a color saturation correction circuit control signal according to the tone correction circuit control signal, and a color saturation correction circuit control using the output from the color saturation correction circuit control device and the luminance signal as inputs. The color saturation correction circuit that applies color saturation correction according to the signal to the color difference signal is provided.
[0009]
According to the present invention, the luminance distribution in one frame is determined from the output of the skin color luminance distribution detection circuit for detecting the luminance distribution of the flesh color portion in one frame from the color difference signal and luminance signal of the video signal and the luminance signal of the video signal. The image state is calculated in the histogram conversion type gradation correction circuit control device from the former or both of the outputs of the luminance distribution detection circuit to be detected, and the histogram conversion type gradation corresponding to the image state is calculated in the histogram conversion type gradation correction circuit control device. A correction circuit control signal is created, and an optimum histogram conversion type gradation correction according to the state of the video signal is performed by an output signal from the histogram conversion type gradation correction circuit control apparatus. A color saturation correction circuit control signal corresponding to the output signal from the histogram conversion type gradation correction circuit control device in FIG. Perform optimum color saturation correction in accordance with the output signals from the histogram conversion type gradation correction circuit controller by the output signal from the saturation correction circuit controller.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 shows a video signal correction circuit according to an embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a skin color luminance distribution detection circuit for detecting the luminance distribution of a flesh color portion in one frame from a video signal. Reference numeral 102 denotes an output from the flesh color luminance distribution detection circuit as an input to make the skin color luminance distribution of one frame. A histogram conversion type tone correction circuit control device for generating a corresponding histogram conversion type tone correction circuit control signal, and reference numeral 103 denotes an output from the histogram conversion type tone correction circuit control device as an input, and histogram conversion type tone correction circuit This is a histogram conversion type gradation correction circuit that applies gradation correction to a luminance signal in accordance with a circuit control signal.
[0011]
The operation of the video signal correction circuit configured as described above will be described below. First, the skin color luminance distribution detection circuit 101 in FIG. 1 detects the luminance distribution of the skin color portion in one frame from the video signal, and converts the detected result into a voltage. Needless to say, the output of the detection circuit may be not only a voltage but also a current. The detected luminance distribution of the skin color portion is input to the histogram conversion type tone correction circuit control device 102 in FIG. 1, and a histogram conversion type tone correction circuit control signal corresponding to the skin color luminance distribution of one frame is created to generate a voltage or current. Convert and output. The output histogram conversion type gradation correction circuit control signal is input to the histogram conversion type gradation correction circuit 103, and the histogram conversion type gradation correction corresponding to the histogram conversion type gradation correction circuit control signal is applied to the luminance signal of the video signal. Multiply.
[0012]
As described above, according to the first embodiment, by detecting the luminance distribution of the skin color portion of one frame, it is possible to perform optimum histogram conversion type gradation correction according to the luminance distribution of the skin color portion of the video.
[0013]
(Embodiment 2)
FIG. 2 is a block diagram of a video signal correction circuit according to an embodiment of the present invention. In FIG. 2, the configuration is different from that of the first embodiment in that a luminance distribution detection circuit 206 is provided in addition to the flesh color luminance distribution detection circuit 101, and the luminance distribution detection circuit 206 has an output in addition to the output of the flesh color luminance distribution detection circuit 101. The output is configured to be input to the histogram conversion type tone correction circuit control device 202. The luminance distribution detection circuit 206 detects the luminance distribution in one frame from the luminance signal. Since other configurations are the same as those of the first embodiment, the description thereof is omitted.
[0014]
The operation of the video signal correction circuit configured as described above will be described below. First, the skin color luminance distribution detection circuit 101 in FIG. 2 detects the luminance distribution of the skin color portion in one frame from the video signal, and converts the detected result into a voltage. Needless to say, the output of the detection circuit may be not only a voltage but also a current. Further, the luminance distribution detection circuit 206 in FIG. 2 detects the luminance distribution in one frame from the video signal, and converts the detected result into voltage or current. The detected luminance distribution of the skin color portion and the luminance distribution are input to the histogram conversion type tone correction circuit control device 202 in FIG. 2, and the luminance distribution of the skin color portion of the video signal in one frame and the luminance distribution in one frame are determined. A histogram conversion type gradation correction circuit control signal is created, converted into voltage or current, and output. The output histogram conversion type gradation correction circuit control signal is input to the histogram conversion type gradation correction circuit 103, and the histogram conversion type gradation correction corresponding to the histogram conversion type gradation correction circuit control signal is applied to the luminance signal of the video signal. Multiply.
[0015]
As described above, according to the second embodiment, by detecting the luminance distribution of the flesh color portion of the video signal in one frame and the luminance distribution in one frame, the luminance distribution and luminance distribution of the flesh color portion of the video are optimal. Histogram conversion type tone correction is possible.
[0016]
(Embodiment 3)
FIG. 3 is a block diagram of a video signal correction circuit according to an embodiment of the present invention. In FIG. 3, reference numeral 101 denotes a skin color luminance distribution detection circuit for detecting the luminance distribution of a flesh color portion in one frame from a video signal. Reference numeral 102 denotes an output from the flesh color luminance distribution detection circuit as an input to generate a flesh color luminance distribution for one frame. A histogram conversion type tone correction circuit control device for generating a corresponding histogram conversion type tone correction circuit control signal, and reference numeral 103 denotes an output from the histogram conversion type tone correction circuit control device as an input, and histogram conversion type tone correction circuit A histogram conversion type tone correction circuit that applies tone correction according to a circuit control signal to a luminance signal, and 304 designates an output from the histogram conversion type tone correction circuit control device as an input and controls the histogram conversion type tone correction circuit. And a color saturation correction circuit control device for generating a color saturation correction circuit control signal according to the signal. The output and color saturation correction in accordance with the color saturation correction circuit control signal a luminance signal as an input from degrees correction circuit controller of the color saturation correction circuit multiplying the color difference signal.
[0017]
The operation of the video signal correction circuit configured as described above will be described below. First, the skin color luminance distribution detection circuit 101 in FIG. 3 detects the luminance distribution of the skin color portion in one frame from the video signal, and converts the detected result into a voltage. Needless to say, the output of the detection circuit may be not only a voltage but also a current. The detected luminance distribution of the skin color portion is input to the histogram conversion type tone correction circuit control device 102 in FIG. 3, and a histogram conversion type tone correction circuit control signal corresponding to the skin color luminance distribution of one frame is created to generate a voltage or current. Convert and output. The output histogram conversion type gradation correction circuit control signal is input to the histogram conversion type gradation correction circuit 103, and the histogram conversion type gradation correction corresponding to the histogram conversion type gradation correction circuit control signal is applied to the luminance signal of the video signal. Multiply. Also, the output histogram conversion type gradation correction circuit control signal is input to the color saturation correction circuit control device 304 to create a color saturation correction circuit control signal corresponding to the histogram conversion type gradation correction circuit control signal, Convert to current and output. The output color saturation correction circuit control signal is input to the color saturation correction circuit 305, and color saturation correction according to the color saturation correction circuit control signal is applied to the color difference signal of the video signal.
[0018]
As described above, according to the third embodiment, by detecting the luminance distribution of the flesh-colored portion of one frame, it is possible to perform optimum histogram conversion type gradation correction according to the luminance distribution of the flesh-colored portion of the video, and the histogram. Optimum color saturation correction according to conversion type gradation correction is possible.
[0019]
(Embodiment 4)
FIG. 4 is a block diagram of a video signal correction circuit according to an embodiment of the present invention. In FIG. 4, the configuration is different from that of the third embodiment in that a luminance distribution detection circuit 6 is provided in addition to the flesh color luminance distribution detection circuit 101, and the luminance distribution detection circuit 6 has an output in addition to the output of the flesh color luminance distribution detection circuit 1. The output is configured to be input to the histogram conversion type tone correction circuit control device. The luminance distribution detection circuit 206 detects the luminance distribution in one frame from the luminance signal. Since other configurations are the same as those in the third embodiment, the description thereof is omitted.
[0020]
The operation of the video signal correction circuit configured as described above will be described below. First, the skin color luminance distribution detection circuit 101 in FIG. 4 detects the luminance distribution of the skin color portion in one frame from the video signal, and converts the detected result into a voltage. Needless to say, the output of the detection circuit may be not only a voltage but also a current. Further, the luminance distribution detection circuit 206 in FIG. 4 detects the luminance distribution in one frame from the video signal, and converts the detected result into voltage or current. The detected luminance distribution of the skin color portion and the luminance distribution are input to the histogram conversion type tone correction circuit control device 202 in FIG. 4, and the luminance distribution of the skin color portion of the video signal in one frame and the luminance distribution in one frame are determined. A histogram conversion type gradation correction circuit control signal is created, converted into voltage or current, and output. The output histogram conversion type gradation correction circuit control signal is input to the histogram conversion type gradation correction circuit 103, and the histogram conversion type gradation correction corresponding to the histogram conversion type gradation correction circuit control signal is applied to the luminance signal of the video signal. Multiply. Also, the output histogram conversion type gradation correction circuit control signal is input to the color saturation correction circuit control device 304 to create a color saturation correction circuit control signal corresponding to the histogram conversion type gradation correction circuit control signal, Convert to current and output. The output color saturation correction circuit control signal is input to the color saturation correction circuit 305, and color saturation correction according to the color saturation correction circuit control signal is applied to the color difference signal of the video signal.
[0021]
As described above, according to the fourth embodiment, by detecting the luminance distribution of the flesh color portion of the video signal in one frame and the luminance distribution in one frame, the luminance distribution and luminance distribution of the flesh color portion of the video are optimal. Histogram conversion type gradation correction can be performed, and optimum color saturation correction according to the histogram conversion type gradation correction can be performed.
[0022]
(Embodiment 5)
FIG. 5 is a block diagram of a histogram conversion type tone correction circuit control device according to an embodiment of the present invention. In the present embodiment, a case of histogram conversion type gradation correction having N divided luminance areas divided into two or more as shown in FIG. 8 will be described.
[0023]
In FIG. 5, reference numeral 507 denotes an input of P [i + 1] to P [N], which is the luminance distribution of the skin color portion in the higher luminance area than the luminance area i in one frame, in the higher luminance area than the luminance area i in the one frame. An inclination increase amount calculation circuit for creating a correction amount to be added to the histogram conversion type gradation correction inclination according to the luminance distribution P [i + 1] to P [N] of the flesh color part, and 508 is from the luminance area i in one frame. The luminance distributions P [1] to P [1] of the skin color portion in the lower luminance region than the luminance region i in the one frame are input with the luminance distributions P [1] to P [i-1] of the skin color portion in the low luminance region. An inclination reduction amount calculation circuit for generating a correction amount subtracted from the histogram conversion type gradation correction basic inclination according to [i-1], and 509 is a hysteresis that does not depend on the video signal in the luminance region i. An adder which receives the output from the gram conversion type gradation correction basic gradient B [i] and the gradient increase amount calculation circuit as an input and outputs the calculation result, 510 is the output of the adder and the gradient decrease amount calculation circuit The subtractor outputs the skin color luminance distribution adaptive histogram conversion type tone correction gradient G [i] in the luminance region i as an input, and 511 denotes the skin color luminance distribution adaptive histogram conversion type tone correction in the entire luminance region. It is a histogram conversion type gradation correction circuit control signal calculation circuit that creates a histogram conversion type gradation correction circuit control signal with an inclination as an input.
The video signal correction circuit in the one embodiment of the present invention is the same as that in the first embodiment, and the description thereof is omitted.
[0024]
The operation of the histogram conversion type tone correction circuit control apparatus configured as described above will be described below.
First, the luminance distribution P [i + 1] to P [N] of the skin color portion in the higher luminance region than the luminance region i with respect to the histogram conversion type gradation correction basic inclination B [i] that does not depend on the video signal in the luminance region i. The output of the slope increase calculation circuit 507 created according to the above is added, and the slope reduction created according to the skin tone color distributions P [1] to P [i-1] in the lower brightness area than the brightness area i. The output of the quantity calculation circuit 508 is subtracted to create a flesh color luminance distribution adaptive histogram conversion type gradation correction gradient G [I] in the luminance region i, which is converted into voltage or current and output. Note that the output of the slope decrease amount calculation circuit 508 with respect to the histogram conversion type gradation correction basic gradient B [1] is zero, and the output of the slope increase amount calculation circuit 507 with respect to the histogram conversion type gradation correction basic gradient B [N] is It goes without saying that it is zero.
[0025]
Next, the output skin tone luminance distribution adaptive histogram conversion type gradation correction gradient G in each luminance region is input to the histogram conversion type tone correction circuit control signal calculation circuit, and the skin color luminance distribution adaptive histogram conversion type floor in each luminance region is input. A histogram conversion type tone correction circuit control signal corresponding to the tone correction gradient is created, converted into voltage or current, and output.
[0026]
Since the operations other than the histogram conversion type tone correction circuit control device are the same as those in the first embodiment, the description thereof will be omitted.
[0027]
As described above, according to the fifth embodiment, the optimum histogram conversion type tone correction circuit control signal corresponding to the luminance distribution of the skin color portion of the video is generated by detecting the luminance distribution of the skin color portion in one frame. Thus, it is possible to perform optimum histogram conversion type tone correction according to the luminance distribution of the skin color portion of the video without impairing the tone property of the skin color portion.
[0028]
(Embodiment 6)
FIG. 6 is a block diagram of a histogram conversion type tone correction circuit control device according to an embodiment of the present invention. In the present embodiment, a case of histogram conversion type gradation correction having N divided luminance areas divided into two or more as shown in FIG. 8 will be described.
[0029]
In FIG. 6, the configuration is different from the histogram conversion type gradation correction circuit control device of the fifth embodiment described above. The luminance distribution adaptive histogram conversion type according to the luminance distribution in one frame with the luminance distribution in one frame as an input. The luminance distribution adaptive histogram conversion type gradation correction inclination calculation circuit 612 for generating the gradation correction inclination H [i] is provided, and the histogram conversion type gradation correction basic inclination B [i] independent of the video signal in the fifth embodiment is provided. Is replaced.
[0030]
Other configurations relating to the histogram conversion type tone correction circuit control device are the same as those in the fifth embodiment, and thus the description thereof is omitted.
[0031]
The video signal correction circuit in the embodiment of the present invention is the same as that in the second embodiment, and the description thereof is omitted.
[0032]
The operation of the histogram conversion type tone correction circuit control apparatus configured as described above will be described below.
First, a luminance distribution adaptive histogram conversion type gradation correction inclination calculation circuit 612 that generates a luminance distribution adaptive histogram conversion type gradation correction inclination H [i] corresponding to the luminance distribution in one frame by using the luminance distribution in one frame as an input. , A luminance distribution adaptive histogram conversion type gradation correction gradient H [i] corresponding to the luminance distribution in one frame is generated, converted into a voltage or a current, and output.
[0033]
Next, with respect to the luminance distribution adaptive histogram conversion type gradation correction inclination H [i] in the luminance region i, P [i + 1] to P [N] which are luminance distributions of the skin color portion in the luminance region higher than the luminance region i. The output of the slope increase amount calculation circuit 507 created according to the above is added, and it is created according to p [1] to P [i-1] which is the luminance distribution of the skin color portion in the luminance region lower than the luminance region i. The output of the inclination reduction amount calculation circuit 508 is reduced to create a skin color luminance distribution adaptive histogram conversion type gradation correction gradient G [i] in the luminance region i, which is converted into voltage or current and output. Note that the output of the slope decrease amount calculation circuit 508 with respect to the histogram conversion type gradation correction basic inclination H [1] is zero, and the output of the inclination increase amount calculation circuit 507 with respect to the histogram conversion type gradation correction basic inclination H [N] is Needless to say, it is zero.
[0034]
Next, the output skin color luminance distribution adaptive histogram conversion type gradation correction gradient G in each luminance region is input to the histogram conversion type gradation correction circuit control signal calculation circuit, and the skin color luminance distribution adaptive histogram conversion type floor in each luminance region is input. A histogram conversion type tone correction circuit control signal corresponding to the tone correction gradient is created, converted into voltage or current, and output.
[0035]
Since the operations other than the histogram conversion type tone correction circuit control device are the same as those in the second embodiment, description thereof is omitted.
[0036]
As described above, according to the sixth embodiment, by detecting the luminance distribution of the flesh color portion in one frame and the luminance distribution in one frame, the optimum histogram conversion type gradation corresponding to the luminance distribution of the flesh color portion of the image is obtained. By creating a correction circuit control signal, it is possible to perform optimum histogram conversion type gradation correction according to the luminance distribution of the skin color portion of the video without impairing the gradation of the skin color portion.
[0037]
(Embodiment 7)
Since the configuration of the histogram conversion type tone correction circuit control device in one embodiment of the present invention is the same as that of the fifth embodiment, the description thereof is omitted.
[0038]
The video signal correction circuit in the one embodiment of the present invention is the same as that in the third embodiment, and the description thereof is omitted.
[0039]
Since the operation of the histogram conversion type tone correction circuit control device is the same as that of the fifth embodiment, the description thereof is omitted.
[0040]
Since the operations other than the histogram conversion type tone correction circuit control device are the same as those in the third embodiment, the description thereof will be omitted.
[0041]
As described above, according to the seventh embodiment, an optimal histogram conversion type tone correction circuit control signal corresponding to the luminance distribution of the skin color portion of the video is generated by detecting the luminance distribution of the skin color portion in one frame. In addition, it is possible to perform optimum histogram conversion type gradation correction according to the luminance distribution of the skin color part of the image without impairing the gradation property of the skin color part, and optimum color saturation correction according to the histogram conversion type gradation correction Is possible.
[0042]
(Embodiment 8)
Since the configuration of the histogram conversion type tone correction circuit control device in one embodiment of the present invention is the same as that of the sixth embodiment, description thereof is omitted.
[0043]
The video signal correction circuit in the one embodiment of the present invention is the same as that in the fourth embodiment, and the description thereof is omitted.
Since the operation of the histogram conversion type tone correction circuit control device is the same as that of the sixth embodiment, description thereof is omitted.
[0044]
Since the operations other than the histogram conversion type tone correction circuit control device are the same as those in the fourth embodiment, description thereof will be omitted.
[0045]
As described above, according to the eighth embodiment, by detecting the luminance distribution of the flesh color portion in one frame and the luminance distribution in one frame, the optimum histogram conversion type gradation corresponding to the luminance distribution of the flesh color portion of the image is obtained. By creating a correction circuit control signal, it is possible to perform optimum histogram conversion type gradation correction according to the luminance distribution of the skin color part of the image without impairing the gradation of the skin color part. The optimum color saturation correction can be performed.
[0046]
【The invention's effect】
As described above, the present invention enables the viewer to view with optimal histogram conversion type gradation correction and color saturation correction according to the luminance distribution of the flesh color portion of the video signal and the luminance distribution of the video signal. Yes, its practical effect is great.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram of a video signal correction circuit according to a first embodiment and a fifth embodiment of the present invention. FIG. 2 is a block diagram according to a second embodiment and a sixth embodiment of the present invention. FIG. 3 is a block diagram of a video signal correction circuit. FIG. 4 is a block diagram of a video signal correction circuit according to the third and seventh embodiments of the present invention. FIG. 5 is a block diagram of a video signal correction circuit according to the eighth embodiment and FIG. 5 is a block diagram of a histogram conversion type tone correction circuit controller according to the fifth and seventh embodiments of the present invention. FIG. 6 is a block configuration diagram of a histogram conversion type tone correction circuit control device in the sixth embodiment and the eighth embodiment of the present invention. FIG. 7 is a block configuration diagram of a conventional flesh color luminance enhancement circuit. 8] Split Illustration of degrees area [Description of symbols]
DESCRIPTION OF SYMBOLS 101 Skin color luminance distribution detection circuit 102, 202 Histogram conversion type gradation correction circuit control apparatus 103 Histogram conversion type gradation correction circuit 304 Color saturation correction circuit control apparatus 305 Color saturation correction circuit 206 Luminance distribution detection circuit 507 Inclination increase amount calculation Circuit 508 Inclination reduction amount calculation circuit 509 Adder 510 Subtractor 511 Histogram conversion type gradation correction circuit control signal calculation circuit 512 Luminance distribution adaptive histogram conversion type gradation correction inclination calculation circuit

Claims

A skin color luminance distribution detection circuit for detecting the luminance distribution of a flesh color portion in one frame from the color difference signal and luminance signal of the video signal, and a histogram conversion type for an arbitrary luminance in one frame with the output from the flesh color luminance distribution detection circuit as an input. Histogram conversion type gradation correction circuit control in which the gradation correction inclination is increased according to the luminance distribution of the skin color portion in the higher luminance region than the arbitrary luminance and decreased according to the luminance distribution of the skin color portion in the lower luminance region than the arbitrary luminance. A third histogram conversion type tone correction circuit control device for generating a signal, and an output from the histogram conversion type tone correction circuit control device as an input to perform tone correction according to the histogram conversion type tone correction circuit control signal; A gradation conversion type gradation correction circuit for multiplying the luminance signal is provided, according to the luminance distribution of the skin color portion of the video signal in one frame Video signal correction circuit, characterized in that multiplying the histogram conversion type gradation correction on the luminance signal of the image signal.

A skin color luminance distribution detection circuit for detecting a luminance distribution of a flesh color portion in one frame from a color difference signal and a luminance signal of a video signal; a luminance distribution detection circuit for detecting a luminance distribution in one frame from a luminance signal of the video signal; Arbitrary luminance in one frame with respect to the histogram conversion type tone correction circuit control signal generated according to the luminance distribution in one frame with the output from the skin color luminance distribution detection circuit and the output from the luminance distribution detection circuit as input. Histogram conversion type gradation correction gradient with respect to the histogram is increased in accordance with the luminance distribution of the skin color portion in the higher luminance region than the arbitrary luminance and decreased in accordance with the luminance distribution of the skin color portion in the lower luminance region than the arbitrary luminance. A fourth histogram conversion type gradation correction circuit control device for creating a tone correction circuit control signal, and the histogram conversion type gradation correction A histogram conversion type gradation correction circuit that receives the output from the road control device and applies gradation correction according to the histogram conversion type gradation correction circuit control signal to the luminance signal; A video signal correction circuit which applies a histogram conversion type gradation correction to a luminance signal of a video signal in accordance with the luminance distribution and the luminance distribution in one frame.

A skin color luminance distribution detection circuit for detecting the luminance distribution of a flesh color portion in one frame from the color difference signal and luminance signal of the video signal, and a histogram conversion type for an arbitrary luminance in one frame with the output from the flesh color luminance distribution detection circuit as an input. Histogram conversion type gradation correction circuit control in which the gradation correction inclination is increased according to the luminance distribution of the skin color portion in the higher luminance region than the arbitrary luminance and decreased according to the luminance distribution of the skin color portion in the lower luminance region than the arbitrary luminance. A third histogram conversion type tone correction circuit control device for generating a signal, and an output from the histogram conversion type tone correction circuit control device as an input to perform tone correction according to the histogram conversion type tone correction circuit control signal; The histogram conversion type gradation correction circuit to be applied to the luminance signal and the output from the histogram conversion type gradation correction circuit controller are input. A color saturation correction circuit control device that generates a color saturation correction circuit control signal according to the histogram conversion type gradation correction circuit control signal, and a color using the output from the color saturation correction circuit control device and the luminance signal as input Saturation correction circuit A color saturation correction circuit that applies color saturation correction to a color difference signal according to a control signal is provided, and is converted into a luminance signal of a video signal in accordance with the luminance distribution of the flesh color portion of the video signal in one frame. A video signal correction circuit for correcting a color difference signal of a video signal by applying type gradation correction.

A skin color luminance distribution detection circuit for detecting a luminance distribution of a flesh color portion in one frame from a color difference signal and a luminance signal of a video signal; a luminance distribution detection circuit for detecting a luminance distribution in one frame from a luminance signal of the video signal; Arbitrary luminance in one frame with respect to the histogram conversion type tone correction circuit control signal generated according to the luminance distribution in one frame with the output from the skin color luminance distribution detection circuit and the output from the luminance distribution detection circuit as input. Histogram conversion type gradation correction gradient with respect to the histogram is increased in accordance with the luminance distribution of the skin color portion in the higher luminance region than the arbitrary luminance and decreased in accordance with the luminance distribution of the skin color portion in the lower luminance region than the arbitrary luminance. A fourth histogram conversion type gradation correction circuit control device for creating a tone correction circuit control signal, and the histogram conversion type gradation correction A histogram conversion type gradation correction circuit that applies an output from the path control device to the luminance signal according to a histogram conversion type gradation correction circuit control signal, and a histogram conversion type gradation correction circuit control device; A color saturation correction circuit control device for creating a color saturation correction circuit control signal corresponding to the histogram conversion type gradation correction circuit control signal using the output as an input, and the output and luminance signal from the color saturation correction circuit control device. A color saturation correction circuit that multiplies the color difference signal by color saturation correction according to a color saturation correction circuit control signal as an input is provided. The luminance distribution of the flesh color portion of the video signal in one frame and the luminance distribution in one frame are provided. Accordingly, a video signal correction circuit characterized in that the luminance signal of the video signal is subjected to histogram conversion type gradation correction and the color difference signal of the video signal is corrected.