JP4051097B2 - How to set gray balance - Google Patents

Description

【００３１】
そして、前記（１）式の関係を満たす係数Ａを、次の（３）式に示すＥが最小となるように、最小自乗法を用いて求める。なお、（３）式において、ｋは各データの番号を表し、また、上付記号のＴはマトリクスの行と列を入れ換えた転置を表す。
【００３２】
【数２】

【００３３】
（３）式から係数Ａが求められると、各４次元平面が決定する。次に、このようにして求められた４次元平面Ｘ−ＲＧＢ、Ｙ−ＲＧＢ、Ｚ−ＲＧＢ上において、デバイスデータＲ、Ｇ、Ｂから十分離れた位置にある仮想デバイスデータＲｉ、Ｇｉ、Ｂｉおよびそれに対応する仮想測色値Ｘｉ、Ｙｉ、Ｚｉを求める。
【００３４】
図８は、デバイスデータＲ、Ｇ、Ｂおよび仮想デバイスデータＲｉ、Ｇｉ、Ｂｉと、測色値Ｘ、Ｙ、Ｚおよび仮想測色値Ｘｉ、Ｙｉ、Ｚｉとの関係を２次元的模式図として示したものである。すなわち、記録媒体上に形成された暫定グレーバランス設定チャートから得られるデバイスデータＲ、Ｇ、Ｂと測色値Ｘ、Ｙ、Ｚとの関係は、前述した知見から、例えば、点ｂ１〜ｂ４に示すように、単調減少の関係にある。そして、これらの点ｂ１〜ｂ４を用いて最小自乗法により算出された４次元平面を点線で示すと、前記４次元平面上の仮想デバイスデータＲｉ、Ｇｉ、Ｂｉに対応する仮想測色値Ｘｉ、Ｙｉ、Ｚｉを表す点ｄ１、ｄ２と点ｂ１〜ｂ４とを結ぶ平面は、実線で示すように単調減少の関係となる。従って、前記のようにして、最小自乗法を用いて仮想デバイスデータＲｉ、Ｇｉ、Ｂｉに対する仮想測色値Ｘｉ、Ｙｉ、Ｚｉを生成することにより、仮想デバイスデータＲｉ、Ｇｉ、Ｂｉを含むデバイスデータＲ、Ｇ、Ｂと、仮想測色値Ｘｉ、Ｙｉ、Ｚｉを含む測色値Ｘ、Ｙ、Ｚとの間で単調関係を維持することができる。
【００３５】
以上のようにして仮想デバイスデータＲｉ、Ｇｉ、Ｂｉに対する仮想測色値Ｘｉ、Ｙｉ、Ｚｉを求めた後、前記仮想デバイスデータＲｉ、Ｇｉ、Ｂｉを含むデバイスデータＲ、Ｇ、Ｂを前記仮想測色値Ｘｉ、Ｙｉ、Ｚｉを含む測色値Ｘ、Ｙ、Ｚに変換する変換テーブルｇを設定する。なお、この変換関係は、
ＸＹＺ＝ｇ（ＲＧＢ） …（４）
と表記するものとする。次に、前記変換テーブルｇを用いて、ニュートンラフソン法やデータ線形補間法等の繰り返し演算法により、測色値Ｘ、Ｙ、ＺをデバイスデータＲ、Ｇ、Ｂに変換するための逆変換テーブルｇ^-1を求める（ステップＳ１５）。
【００３６】
図９は、前記逆変換テーブルｇ^-1を求める処理のフローチャートである。そこで、グレーバランスを求めるのであるから、Ｌ^* ａ^* ｂ^* 空間のａ^* ＝ｂ^* ＝０となるグレー色の目標値（Ｌ^* ，０，０）に対応するＸＹＺ空間の目標値を（Ｘ０，Ｙ０，Ｚ０）とし、繰り返し演算での許容誤差をΔＥ_min に設定する（ステップＳ２０）。次いで、ＲＧＢ空間での既知の初期値（Ｒ１，Ｇ１，Ｂ１）を設定し（ステップＳ２１）、前記テーブルｇを用いて、前記初期値（Ｒ１，Ｇ１，Ｂ１）に対する測色値（Ｘ１，Ｙ１，Ｚ１）を求める（ステップＳ２２）。そして、目標値（Ｘ０，Ｙ０，Ｚ０）と前記測色値（Ｘ１，Ｙ１，Ｚ１）との誤差量ΔＥを求め（ステップＳ２３）、前記誤差量ΔＥと許容誤差ΔＥ_min とを比較する（ステップＳ２４）。この場合、｜ΔＥ｜＜ΔＥ_min でなければ、修正値（ΔＲ，ΔＧ，ΔＢ）を算出し（ステップＳ２５）、初期値（Ｒ１，Ｇ１，Ｂ１）を前記修正値（ΔＲ，ΔＧ，ΔＢ）だけ修正した後（ステップＳ２６）、ステップＳ２２〜Ｓ２４の処理を繰り返す。
【００３７】
ここで、前記修正値（ΔＲ，ΔＧ，ΔＢ）は、次のようにして求められる。すなわち、図１０に示すように、任意のデバイスデータＲ、Ｇ、Ｂが与えられたとき、このデバイスデータＲ、Ｇ、Ｂ（点ｃで示す）に対する測色値Ｘ、Ｙ、Ｚは、８つの格子点ｃ０〜ｃ７におけるデバイスデータ（Ｒ₀ ，Ｇ₀ ，Ｂ₀ ）〜（Ｒ₇ ，Ｇ₇ ，Ｂ₇ ）に対応する測色値（Ｘ₀ ，Ｙ₀ ，Ｚ₀ ）〜（Ｘ₇ ，Ｙ₇ ，Ｚ₇ ）、格子点ｃ０〜ｃ７で囲まれる直方体の体積Ｖ、前記直方体内の任意の補間点ｃにより８分割された体積Ｖ０〜Ｖ７を用いて、
【００３８】
【数３】

【００３９】
として求めることができる。この場合、（５）式〜（７）式の関係において、デバイスデータＲ、Ｇ、Ｂに対する測色値Ｘ、Ｙ、Ｚが微小範囲内で線形であると仮定すると、前記デバイスデータＲ、Ｇ、Ｂの微小変化量である修正値（ΔＲ，ΔＧ，ΔＢ）と前記測色値Ｘ、Ｙ、Ｚの微小変化量（ΔＸ，ΔＹ，ΔＺ）とは、
【００４０】
【数４】

【００４１】
の関係を満たすことになる。なお、Ｊはヤコビアン行列である。（８）式において、ヤコビアン行列Ｊが求まれば、デバイスデータＲ、Ｇ、Ｂの修正値（ΔＲ，ΔＧ，ΔＢ）に対する測色値Ｘ、Ｙ、Ｚの微小変化量（ΔＸ，ΔＹ，ΔＺ）を予測することができる。この場合、前記ヤコビアン行列Ｊは、（５）式〜（７）式をデバイスデータＲ、Ｇ、Ｂで偏微分することで求められる。従って、デバイスデータＲ、Ｇ、Ｂの修正値（ΔＲ，ΔＧ，ΔＢ）は、
【００４２】
【数５】

【００４３】
として求められる。
【００４４】
以上のようにして得られるヤコビアン行列Ｊを用いて繰り返し計算を行うことにより、任意のグレー色の目標値Ｘ０、Ｙ０、Ｚ０に対するデバイスデータＲ、Ｇ、Ｂの関係を表す逆変換テーブルｇ^-1を求めることができる。なお、前記逆変換テーブルｇ^-1は、Ｌ^* ａ^* ｂ^* 空間の目標値Ｌ^* 、０、０に対するデバイスデータＲ、Ｇ、Ｂの関係として求めることもできる。
【００４５】
ここで、ニュートンラフソン法では、収束の条件として、求める解を有する方程式が単調関数であることが必要である。この場合、仮想デバイスデータＲｉ、Ｇｉ、Ｂｉを含むデバイスデータＲ、Ｇ、Ｂと仮想測色値Ｘｉ、Ｙｉ、Ｚｉを含む測色値Ｘ、Ｙ、Ｚとの間には、単調関係が成立しており、しかも、デバイス空間および測色値空間が仮想空間にまで拡大されており、繰り返し演算中において算出される全てのデバイスデータＲ、Ｇ、Ｂおよび測色値Ｘ、Ｙ、Ｚが存在するため、発散することなく確実に繰り返し演算を実行し、正確な値を得ることができる。
【００４６】
なお、ニュートンラフソン法を適用するにあたり、本実施形態では、図５に示すように、デバイスデータＲ、Ｇ、Ｂから得られる暫定グレーバランス設定チャートの特性が線形特性ａ５となるように修正出力調整データａ６を設定している。この場合、デバイスデータＲ、Ｇ、Ｂに対する測色値Ｘ、Ｙ、Ｚの関係が線形となるため、非線形なテストチャート測定データａ４に比較して誤差の少ない演算を遂行することができる。すなわち、テストチャート測定データａ４を用いた場合には、デバイスデータＲ、Ｇ、Ｂの変化に対する明度Ｌ^* の変化が前記デバイスデータＲ、Ｇ、Ｂによって大きくなる場合があり（図５参照）、その分誤差が生じ易くなるが、線形特性ａ５を用いると、明度Ｌ^* の全範囲で上記の場合に比較して変化量を略一定とすることができ、安定した演算が可能となるからである。
【００４７】
以上のようにして求められた逆変換テーブルｇ^-1を構成するデータは、図１１に示すように、グレー色を与える明度Ｌ^* （ａ^* ＝ｂ^* ＝０）とデバイスデータＲ、Ｇ、Ｂとの関係を表しており、これを暫定グレーバランスとして設定する（ステップＳ１６、図６）。
【００４８】
［３］ 前記のようにして設定された暫定グレーバランスは、図７に示すように、ラフに設定された暫定グレーバランス設定チャートに従って近似的に求められたものであるため、十分に精度のよいグレーバランスを構成しているわけではない。そこで、前記暫定グレーバランスを用いてチャートを出力し、それを用いてさらに精度の高い最終グレーバランスを求める作業を行う。図１２は、最終グレーバランスの設定手順を示すフローチャートである。
【００４９】
先ず、［２］で作成された暫定グレーバランスを用いて［１］で作成された修正出力調整データａ６を修正し（ステップＳ３０）、Ｒ＝Ｇ＝Ｂのときに所望の明度Ｌ^* を有したグレー色を出力することのできる暫定的にグレーバランスが調整された出力調整データを求め、この出力調整データを出力調整部２６にダウンロードする（ステップＳ３１）。
【００５０】
次に、前記出力調整データを用いて、Ｒ＝Ｇ＝Ｂを含むグレー色近傍のデバイスデータＲ、Ｇ、ＢをレーザパワーデータＰｒ、Ｐｇ、Ｐｂに変換する。そして、このレーザパワーデータＰｒ、Ｐｇ、Ｐｂに基づき、記録媒体上に最終グレーバランス設定チャートを作成する（ステップＳ３２）。なお、この最終グレーバランス設定チャートは、暫定グレーバランスに基づいて設定された出力調整データより作成されるもので、例えば、図１３の斜線で示す範囲内の黒点上の測色点であり、グレー色またはその近傍の測色点に対応し、図７に示す暫定グレーバランス設定チャートよりも細かいピッチに設定されている。
【００５１】
次いで、前記最終グレーバランス設定チャートの測色値Ｘ、Ｙ、Ｚを測定器によって測定する（ステップＳ３３）。さらに、前記範囲外の十分離れた位置に仮想デバイスデータＲｉ、Ｇｉ、Ｂｉを設定し（ステップＳ３４）、この仮想デバイスデータＲｉ、Ｇｉ、Ｂｉに対応する仮想測色値Ｘｉ、Ｙｉ、Ｚｉを求める（ステップＳ３５）。
【００５２】
以下、図６に示す［２］のステップＳ１５およびＳ１６の場合と同様にして、各ステップＳ３６およびＳ３７の処理を行うことにより、高精度なグレー色を得ることのできる最終グレーバランスが算出される。そして、この最終グレーバランスから、Ｒ＝Ｇ＝Ｂのときに所望の明度Ｌ^* を有したグレー色を出力することのできるグレーバランスが高精度に調整された出力調整データが求められ、基準出力装置１０に記憶される（ステップＳ３８）。
【００５３】
以上のようにして、［２］においてラフなピッチで設定したグレーバランス設定チャートを用いて暫定グレーバランスを求めた後、［３］においてグレー色近傍のより細かいピッチで設定したグレーバランス設定チャートを用いて最終グレーバランスを求めることにより、少ないパッチ数からなるグレーバランス設定チャートを用いて高速度に最終グレーバランスを求めることができる。また、前記グレーバランス設定チャートのピッチを徐々に細分化して前記の［３］の処理を繰り返し行うことにより、さらに高精度なグレーバランスを設定することができる。
【００５４】
なお、処理時間に不具合がない場合には、［２］の処理において暫定グレーバランスを求めるために使用する修正出力調整データから得られる暫定グレーバランス設定チャートを予め細分化して設定することにより、それを用いて前記の［３］の処理を行うことなく最終グレーバランスを一度に求めることも可能である。
【００５５】
以上に説明した［１］〜［３］の手順、あるいは、他の任意の方法によって設定された基準出力装置１０のグレーバランスを用いて、所望の対象出力装置１２におけるグレーバランスの設定を行う。なお、以下の説明において、基準出力装置１０に係るデータについてはデータの末尾に必要に応じて（ｍ）を付し、対象出力装置１２に係るデータについてはデータの末尾に必要に応じて（ｏｂ）を付すものとする。
【００５６】
そこで、前記基準出力装置１０のグレーバランスが設定された前記修正出力調整データを、デバイスデータＲ、Ｇ、Ｂ（ｍ）をレーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）に変換するための基準出力装置１０の基準出力調整データα（ｍ）とする。また、前記基準出力装置１０において、前記基準出力調整データα（ｍ）を用いて、グレー色近傍を細かく設定した全色領域のチャートを記録媒体上に作成し（ステップＳＡ２）、その測色値Ｌ^* 、ａ^* 、ｂ^* （ｍ）を測定することにより（ステップＳＡ３）、デバイスデータＲ、Ｇ、Ｂ（ｍ）と前記測色値Ｌ^* 、ａ^* 、ｂ^* （ｍ）との関係を表す第１基準出力特性データβ（ｍ）を求める。
【００５７】
そして、前記基準出力調整データα（ｍ）および前記第１基準出力特性データβ（ｍ）から、レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）と測色値Ｌ^* 、ａ^* 、ｂ^* （ｍ）との関係を示す第２基準出力特性データγ（ｍ）を求める（ステップＳＡ４）。これらの基準出力調整データα（ｍ）、第１基準出力特性データβ（ｍ）および第２基準出力特性データγ（ｍ）は、対象出力装置１２のグレーバランス設定部２０に供給される。
【００５８】
次に、所望の対象出力装置１２において、その出力機１６の調整前の出力調整データδ（ｏｂ）を用いて、グレー色を形成すべきデバイスデータＲ、Ｇ、Ｂ（Ｒ＝Ｇ＝Ｂ）（ｏｂ）（図１４のデータａ参照）をレーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｏｂ）（図１４のデータｂ参照）に変換し、前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｏｂ）に基づいて記録媒体Ｆ上にチャートを作成する（ステップＳａ１）。
【００５９】
前記チャートを測定器１８によって測定し、測色値Ｌ^* 、ａ^* 、ｂ^* （ｏｂ）を求める（ステップＳａ２、図１４のデータｃ参照）。なお、当該対象出力装置１２のレーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｏｂ）（図１４のデータｂ参照）と測色値Ｌ^* 、ａ^* 、ｂ^* （ｏｂ）（図１４のデータｃ参照）との関係を出力特性データε（ｏｂ）とし、基準出力調整データα（ｍ）、第２基準出力特性データγ（ｍ）、出力調整データδ（ｏｂ）、出力特性データε（ｏｂ）の関係を図１４に示す。
【００６０】
この場合、前記測色値Ｌ^* 、ａ^* 、ｂ^* （ｏｂ）（図１４のデータｃ参照）がグレー色に対応した所望の値、すなわち、ａ^* ＝ｂ^* であれば、当該対象出力装置１２のグレーバランスがとれていることになるため、前記出力調整データδ（ｏｂ）をそのままグレーバランスがとれた出力調整データとして対象出力装置１２の出力機１６に設定する（ステップＳａ３）。
【００６１】
一方、グレーバランスがとれていない場合、前記測色値Ｌ^* 、ａ^* 、ｂ^* （ｏｂ）（図１４のデータｃ）に対応する基準出力装置１０のレーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）を第２基準出力特性データγ（ｍ）を用いて求める（ステップＳａ４、図１４のデータｄ参照）。
【００６２】
なお、前記測色値Ｌ^* 、ａ^* 、ｂ^* （ｍ）に対する前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）の関係は、前述したニュートンラフソン法または他の任意の方法を用いて求めることができる。また、前記第２基準出力特性データγ（ｍ）を用いる代わりに、前記第１基準出力特性データβ（ｍ）を用いて、前記測色値Ｌ^* 、ａ^* 、ｂ^* （ｍ）に対する前記デバイスデータＲ、Ｇ、Ｂ（ｍ）の関係をニュートンラフソン法等によって求めた後、前記基準出力調整データα（ｍ）を用いて前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）を求めることで、結果的に、前記測色値Ｌ^*、ａ^* 、ｂ^* （ｍ）に対する前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）の関係を求めるようにしてもよい。
【００６３】
次に、前記デバイスデータＲ、Ｇ、Ｂ（Ｒ＝Ｇ＝Ｂ）（ｏｂ）（図１４のデータａ）を基準出力装置１０に与えた場合のレーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）（図１４のデータｅ）を基準出力調整データα（ｍ）を用いて求め、前記データｄとｅの差データ（ｅ−ｄ）を求める（ステップＳａ５）。
【００６４】
最後に、前記差データ（ｅ−ｄ）を用いて、対象出力装置１２の前記デバイスデータＲ、Ｇ、Ｂ（Ｒ＝Ｇ＝Ｂ）（ｏｂ）（図１４のデータａ）に対するレーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｏｂ）（図１４のデータｆ参照、ｆ−ｂ＝ｅ−ｄ）を補正することで、修正された出力調整データθ（ｏｂ）を求める（ステップＳａ６）。
【００６５】
なお、前記出力調整データθ（ｏｂ）は、差データ（ｅ−ｄ）を用いて求める代わりに、データｄとデータｅの比データｅ／ｄを求め、前記比データｅ／ｄをデータｂに乗算することで求めることもできる。
【００６６】
前記のようにして出力調整データθ（ｏｂ）を求めた後、再びデバイスデータＲ、Ｇ、Ｂ（Ｒ＝Ｇ＝Ｂ）（ｏｂ）から前記出力調整データθ（ｏｂ）を用いてレーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｏｂ）を求め、前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｏｂ）に基づいてチャートを作成する。この処理を所望のグレー色となる測色値Ｌ^* 、ａ^* 、ｂ^* （ｏｂ）が得られるまで繰り返すことにより、当該対象出力装置１２に対して高精度なグレーバランスを設定することのできる出力調整データθが得られる。
【００６７】
このようにして、前記対象出力装置１２では、グレー色となるべきデバイスデータＲ、Ｇ、Ｂ（Ｒ＝Ｇ＝Ｂ）を用いて必要最小限のチャートを出力し、それから容易且つ迅速にグレーバランスを設定することができる。なお、上述した実施形態では、チャートの測色値Ｌ^* 、ａ^* 、ｂ^* を得ることでグレーバランスの設定を行うようにしているが、予めグレー色の積分濃度を求めておくようにしてもよい。
【００６８】
本実施形態の対象出力装置１２では、以上のようにして設定された出力調整データθを用いて画像の変換処理が行われる。
すなわち、プロセッサ１４に供給された画像データＣ、Ｍ、Ｙ、Ｋは、デバイスデータＲ、Ｇ、Ｂに変換された後、出力機１６に転送され、前記デバイスデータＲ、Ｇ、Ｂが前記出力調整データθによってレーザパワーデータＰｒ、Ｐｇ、Ｐｂに変換される。次いで、前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂに基づいてレーザが制御され、記録媒体Ｆ上に所望の画像が形成される。この場合、前記画像は、グレーバランスおよび階調が高精度に調整されており、所望の色が再現されることになる。
【００６９】
なお、グレーバランスは、前述したように、出力機１６の出力調整データθにおいて調整する代わりに、プロセッサ１４にフィードバックし、例えば、デバイスデータとしての測色値Ｌ^* 、ａ^* 、ｂ^* からグレーバランスのとれたデバイスデータＲ、Ｇ、Ｂが得られるように設定することもできる。
【００７０】
次に、対象出力装置１２に対してグレーバランスを設定する他の実施形態について、図１５に示すフローチャートに基づき説明する。
【００７１】
この場合、先ず、前述した［１］〜［３］の処理を基準出力装置１０に対して行うことで、前記基準出力装置１０にグレーバランスを設定しておく（ステップＳＢ１）。
【００７２】
次に、前記基準出力装置１０において、デバイスデータＲ、Ｇ、Ｂ（ｍ）（Ｒ＝Ｇ＝Ｂ）から基準出力調整データα（ｍ）を用いてレーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）を生成し、前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）に基づいてグレー色のチャートを記録媒体上に形成する（ステップＳＢ２）。前記チャートの濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）を測定することにより（ステップＳＢ３）、デバイスデータＲ、Ｇ、Ｂ（ｍ）と前記濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）との関係を表すグレー目標階調データとしての第１基準出力特性データβ’（ｍ）を求める。
【００７３】
そして、前記基準出力調整データα（ｍ）および前記第１基準出力特性データβ’（ｍ）から、レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）と濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）との関係を示す第２基準出力特性データγ’（ｍ）を求める（ステップＳＢ４）。これらの基準出力調整データα（ｍ）、第１基準出力特性データβ’（ｍ）および第２基準出力特性データγ’（ｍ）は、対象出力装置１２のグレーバランス設定部２０に供給される。
【００７４】
次に、所望の対象出力装置１２において、グレー色となるべきデバイスデータＲ、Ｇ、Ｂ（ｏｂ）（Ｒ＝Ｇ＝Ｂ）に基づいてチャートを出力し、その濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｏｂ）を測定する。そして、前述したステップＳａ１〜Ｓａ６の処理と略同様にして、グレーバランスがとれた出力調整データを求める（ステップＳｂ１）。
【００７５】
なお、前記濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）に対する前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）の関係は、前述したニュートンラフソン法または他の任意の方法を用いて求めることができるが、これらのデータの関係は１次元の対応関係にあるため、他の任意の方法を用いて容易に求めることもできる。また、前記第２特性データγ’（ｍ）を用いる代わりに、前記第１特性データβ’（ｍ）を用いて、前記濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）に対する前記デバイスデータＲ、Ｇ、Ｂ（ｍ）の関係を求めた後、前記基準出力調整データα（ｍ）を用いて前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）を求めることで、結果的に、前記濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）に対する前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）の関係を求めるようにしてもよい。さらに、この実施形態では、チャートの濃度値Ｄｒ、Ｄｇ、Ｄｂを得ることでグレーバランスの設定を行うようにしているが、チャートの測色値からグレーバランスを設定するようにしてもよい。
【００７６】
ここで、前記の実施形態では、基準出力装置１０における基準出力調整データα（ｍ）、第１基準出力特性データβ’（ｍ）、第２基準出力特性データγ’（ｍ）、あるいは、基準出力調整データα（ｍ）、第１基準出力特性データβ’（ｍ）を用いて、グレーバランスがとれた出力調整データを求めるようにしているが、デバイスデータＲ、Ｇ、Ｂ（ｍ）に対する濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）の関係を表す前記第１基準出力特性データβ’（ｍ）のみを用いて前記出力調整データを求めることもできる。
【００７７】
すなわち、ステップＳＢ３で求められた基準出力装置１０の前記第２特性データβ’（ｍ）を対象出力装置１２のグレーバランス設定部２０に供給した後、前記対象出力装置１２において、グレー色となるべきデバイスデータＲ、Ｇ、Ｂ（ｏｂ）（Ｒ＝Ｇ＝Ｂ）に基づいてチャートを出力し、その濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｏｂ）を測定する。次いで、同じデバイスデータＲ、Ｇ、Ｂ（Ｒ＝Ｇ＝Ｂ）に対する濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｏｂ）および濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）を対応させ、前記濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）を得ることのできる対象出力装置１２におけるレーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｏｂ）を、前記デバイスデータＲ、Ｇ、Ｂ（ｏｂ）（Ｒ＝Ｇ＝Ｂ）に対して設定することにより、出力調整データを求めることができる。
【００７８】
次に、対象出力装置１２に対してグレーバランスを設定するさらに他の実施形態について、図１６に示すフローチャートおよび図１７に基づき説明する。
【００７９】
この場合、先ず、前述した［１］〜［３］の処理を基準出力装置１０に対して行うことで、前記基準出力装置１０にグレーバランスを設定しておく（ステップＳＣ１）。
【００８０】
次に、前記基準出力装置１０において、デバイスデータＲ、Ｇ、Ｂ（ｍ）から基準出力調整データα（ｍ）を用いてレーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）を生成し、前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）に基づいてＣ、Ｍ、Ｙの単色チャートを記録媒体上に形成する（ステップＳＣ２）。そして、前記単色チャートの濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）を測定することにより（ステップＳＣ３）、デバイスデータＲ、Ｇ、Ｂ（ｍ）と前記濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）との関係を表す単色目標階調データとしての第１基準出力特性データβ’’（ｍ）を求める。そして、前記基準出力調整データα（ｍ）および前記第１基準出力特性データβ’’（ｍ）から、レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｍ）と濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）との関係を示す第２基準出力特性データγ’’（ｍ）を求める（ステップＳＣ４）。これらの基準出力調整データα（ｍ）、第１基準出力特性データβ’’（ｍ）および第２基準出力特性データγ’’（ｍ）は、対象出力装置１２のグレーバランス設定部２０に供給される。
【００８１】
次に、所望の対象出力装置１２において、所望の単色となるべきデバイスデータＲ、Ｇ、Ｂ（ｏｂ）（図１７のデータｇ参照）に基づいて単色チャートを出力し（ステップＳｃ１）、その濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｏｂ）を測定する（ステップＳｃ２、図１７のデータｈ参照）。また、前記デバイスデータＲ、Ｇ、Ｂ（ｏｂ）（データｇ）を基準出力装置１０に与えた場合に得られる濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）（図１７のデータｉ参照）を基準出力装置１０の基準出力調整データα（ｍ）および第２基準出力特性データγ’’（ｍ）を用いて求める（ステップＳｃ３）。
【００８２】
ここで、濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｏｂ）（データｈ）と、濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｍ）（データｉ）とが一致しない場合（ステップＳｃ４）、前記濃度値Ｄｒ、Ｄｇ、Ｄｂ（ｏｂ）（データｉ）に対するレーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｏｂ）（図１７のデータｊ参照）を求める。そして、前記レーザパワーデータＰｒ、Ｐｇ、Ｐｂ（ｏｂ）（データｊ）と前記デバイスデータＲ、Ｇ、Ｂ（ｏｂ）（データｇ）との関係として、基準出力装置１０で出力される単色に一致した単色を得ることのできる当該対象出力装置１２での出力調整データθ（ｏｂ）を求める（ステップＳｃ５）。
【００８３】
なお、前記のようにして設定された出力調整データθ（ｏｂ）を用いて、ステップＳｃ１〜Ｓｃ５の処理を繰り返すことにより、対象出力装置１２における単色の精度を向上させることができる。
【００８４】
単色が以上のようにして調整された後（ステップＳｃ４）、対象出力装置１２において、ステップＳＣ１の場合と略同様にしてグレーバランスの設定処理が行われる（ステップＳｃ６）。この場合、既に単色が調整されているため、当該対象出力装置１２に設定されている出力調整データは、図６に示すフローチャートで説明した暫定グレーバランスが既に求められているものとみなせる。従って、対象出力装置１２では、図１２に示す最終グレーバランスを迅速に求めることができる。
【００８５】
【発明の効果】
以上のように、本発明では、対象出力装置において高精度なグレーバランスを容易に設定することができ、前記グレーバランスが設定された出力調整データを用いて画像の色を高精度に再現することができる。
【００８６】
また、既にグレーバランスの設定された基準出力装置におけるデバイスデータと、それに基づいて出力されたチャートの測定値との関係を用いて、多数の前記対象出力装置のグレーバランスを迅速かつ高精度に設定することができる。
【００８７】
さらに、前記のグレーバランスを設定する処理は、オンラインにより自動的に行わせることができる。
【図面の簡単な説明】
【図１】本実施形態のグレーバランスの設定方法が適用される装置の構成図である。
【図２】対象出力装置におけるグレーバランスの設定方法を示すフローチャートである。
【図３】図１の基準出力装置における出力調整データの作成手順を示すフローチャートである。
【図４】図３での出力調整データの作成手順の説明図である。
【図５】図３での出力調整データの作成手順の説明図である。
【図６】図１の基準出力装置における暫定グレーバランスの設定手順を示すフローチャートである。
【図７】仮想デバイスデータを含むデバイスデータの説明図である。
【図８】最小自乗法による仮想デバイスデータの生成方法の説明図である。
【図９】ニュートンラフソン法によるデバイスデータ算出処理のフローチャートである。
【図１０】体積補間の説明図である。
【図１１】グレーバランスの説明図である。
【図１２】図１の基準出力装置における最終グレーバランスの設定手順を示すフローチャートである。
【図１３】暫定グレーバランスから得られる仮想デバイスデータを含むデバイスデータの説明図である。
【図１４】対象出力装置におけるグレーバランスの設定方法の説明図である。
【図１５】対象出力装置におけるグレーバランスの設定方法の他の実施形態を示すフローチャートである。
【図１６】対象出力装置におけるグレーバランスの設定方法のさらに他の実施形態を示すフローチャートである。
【図１７】対象出力装置におけるグレーバランスの設定方法の説明図である。
【符号の説明】
１０…基準出力装置 １２…対象出力装置
１４…プロセッサ １６…出力機
１８…測定器 ２０…グレーバランス設定部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gray balance setting method that can easily set high-accuracy gray balance for a large number of target output devices by using characteristic data of a reference output device for which gray balance is set.
[0002]
[Prior art]
In recent years, in the fields of printing and printers, a technique has been developed that can obtain a color image composed of C, M, Y, and K by processing image data using a signal processing technique. In this case, it is desired that a color image having a desired color and tone can be obtained with high accuracy from the image data.
[0003]
By the way, in the output device that outputs the color image, a desired color may not be reproduced due to an initial setting state or an influence of a change with time. Therefore, in order to adjust the relationship between the image data and the output color, for example, as shown in Japanese Patent Laid-Open No. 56-141673, a single-color (primary color such as C, M, Y, etc.) halftone color There is a method in which a color conversion table capable of outputting a desired color is created by creating a chart and measuring and feeding back the density of each chart.
[0004]
However, since the gray balance is not adjusted in the above-described prior art, it is possible to reproduce a single color gradation with high accuracy, but the accuracy of the gray color is not necessarily guaranteed. That is, for the gray color formed by superimposing a plurality of single colors, even if each single color is set correctly and a theoretically accurate gray color can be obtained, for example, trapping or dot gain at the time of printing can be obtained. As a result, the ratio of a single color may fluctuate due to influences and the like, and an accurate gray color may not be obtained.
[0005]
On the other hand, as another prior art, as disclosed in Japanese Patent Laid-Open No. 6-237373, a correction in which a gray color shift between two output devices is set so that equivalent neutral density (END) values coincide with each other. Some corrections using a matrix make it possible to adjust the gray balance of the other output device on the basis of one output device in which the gray color is accurately set.
[0006]
However, in this method, although the relationship of the color conversion for converting the image data into the output data is actually nonlinear, the correction is approximately performed by the linear processing using the correction matrix, so that the high accuracy is achieved. It is difficult to adjust the gray balance.
[0007]
In any of the above prior arts, at least when setting the gray balance of the output device serving as a reference, a conversion relationship that can output a chart based on the device data of the output device and make the chart gray Was determined by trial and error as a gray balance, and the work required considerable time.
[0008]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems, and for a large number of target output devices, it is extremely easy and highly accurate to set gray balances using characteristic data of reference output devices set with gray balances. It is an object of the present invention to provide a gray balance setting method that can be performed in a simple manner.
[0009]
[Means for Solving the Problems]
The present invention uses a reference output device (10) in which reference output adjustment data (α (m)) in which gray balance is adjusted is set, Three-dimensional The reference input data (R, G, B (m)) is converted into the reference output adjustment data (α (m)). Three-dimensional Converted into reference output data (Pr, Pg, Pb (m)), Three-dimensional Obtained by outputting a reference chart on an output medium based on the reference output data (Pr, Pg, Pb (m)) and measuring the reference chart Three-dimensional Reference measurement (L ^* , A ^* , B ^* (M) or Dr, Dg, Db (m)) The three-dimensional Reference input data (R, G, B (m)) Convert to First reference output characteristic data (β (m)) of the reference output device (10), or Three-dimensional The reference measurement value (L ^* , A ^* , B ^* (M) or Dr, Dg, Db (m)) The three-dimensional Reference output data (Pr, Pg, Pb (m)) Convert to A first step of obtaining second reference output characteristic data (γ (m)) of the reference output device (10);
Using the target output device (12) having the same configuration as the reference output device (10) for setting the gray balance, a gray color is formed. Three-dimensional Gray input data (R = G = B) is determined by output adjustment data (δ (ob)) before adjustment. Three-dimensional Converted to gray output data (Pr, Pg, Pb (ob)) Three-dimensional Based on the gray output data (Pr, Pg, Pb (ob)), a gray chart is output on an output medium, and the gray chart is measured. Three-dimensional Gray measurement value (L ^* , A ^* , B ^* (Ob) or Dr, Dg, Db (ob)) second step,
Obtained in the second step Three-dimensional The gray measurement value (L ^* , A ^* , B ^* (Ob) or Dr, Dg, Db (ob)) in the reference output device (10) capable of obtaining Three-dimensional Reference output data (Pr, Pg, Pb (m)), the first reference output characteristic data (β (m)) and the reference output adjustment data (α (m)), or the second reference output characteristic data A third step determined using (γ (m));
Three-dimensional Of the reference output device (10) corresponding to the gray input data (R = G = B). Three-dimensional A fourth step of obtaining reference output data (Pr, Pg, Pb (m)) using the reference output adjustment data (α (m));
Obtained in the third step Three-dimensional The reference output data (Pr, Pg, Pb (m)) was obtained in the fourth step. Three-dimensional Correction data (ed) to be corrected to the reference output data (Pr, Pg, Pb (m)) is obtained, and the correction data (ed) is used. Three-dimensional Correcting the gray output data (Pr, Pg, Pb (ob)); Three-dimensional The gray input data (R = G = B) was corrected Three-dimensional A fifth step of obtaining output adjustment data (θ (ob)) to be converted into the gray output data (Pr, Pg, Pb (ob));
It is characterized by comprising.
[0010]
Further, the present invention uses the reference output device (10) in which the reference output adjustment data (α (m)) in which the gray balance is adjusted is set, Three-dimensional The reference gray input data (R = G = B) is determined by the reference output adjustment data (α (m)). Three-dimensional Convert to standard gray output data (Pr, Pg, Pb (m)) Three-dimensional Obtained by outputting a reference gray chart on an output medium based on the reference gray output data (Pr, Pg, Pb (m)) and measuring the reference gray chart Three-dimensional Reference gray measurement values (Dr, Dg, Db (m)) Three-dimensional The reference gray input data (R = G = B) Convert to First reference output characteristic data (β ′ (m)) of the reference output device (10), or Three-dimensional Reference gray measurement value (Dr, Dg, Db (m)) The three-dimensional Reference gray output data (Pr, Pg, Pb (m)) Convert to A first step of obtaining second reference output characteristic data (γ ′ (m)) of the reference output device (10);
A gray color is formed using a target output device having the same configuration as the reference output device (10) for setting the gray balance. Three-dimensional Gray input data (R = G = B) is determined by output adjustment data (δ (ob)) before adjustment. Three-dimensional Converted to gray output data (Pr, Pg, Pb (ob)) Three-dimensional Based on the gray output data (Pr, Pg, Pb (ob)), a gray chart is output on an output medium, and the gray chart is measured. Three-dimensional A second step for obtaining gray measurement values (Dr, Dg, Db (ob));
Using the first reference output characteristic data (β ′ (m)) and the reference output adjustment data (α (m)) or the second reference output characteristic data (γ ′ (m)), the same Three-dimensional The reference gray input data (R = G = B) and Three-dimensional Same for gray input data (R = G = B) Three-dimensional The reference gray measurements (Dr, Dg, Db (m)) and Three-dimensional In the second step, the gray measurement values (Dr, Dg, Db (ob)) were matched. Three-dimensional The gray measurement values (Dr, Dg, Db (ob)) Three-dimensional Of the target output device (12) as the reference gray measurement values (Dr, Dg, Db (m)) Three-dimensional A third step for obtaining the gray output data (Pr, Pg, Pb (ob));
Three-dimensional The gray input data (R = G = B) was obtained in the third step. Three-dimensional A fourth step for obtaining output adjustment data (θ (ob)) to be converted into the gray output data (Pr, Pg, Pb (ob));
It is characterized by comprising.
[0011]
Furthermore, the present invention uses the reference output device (10) in which the reference output adjustment data (α (m)) in which the gray balance is adjusted is set, Three-dimensional The reference monochrome input data (R, G, B (m)) is converted into the reference output adjustment data (α (m)). Three-dimensional Convert to standard monochrome output data (Pr, Pg, Pb (m)) Three-dimensional Obtained by outputting a reference monochrome chart on an output medium based on the reference monochrome output data (Pr, Pg, Pb (m)) and measuring the reference monochrome chart Three-dimensional Standard monochromatic measurement (Dr, Dg, Db (m)) The three-dimensional Standard monochrome input data (R, G, B (m)) Convert to A first step of obtaining reference output characteristic data (β ″ (m)) of the reference output device (10);
Using the target output device (12) having the same configuration as the reference output device (10) for setting the gray balance, a desired single color is formed. Three-dimensional Monochromatic input data (R, G, B (ob)) is converted into output adjustment data (δ (ob)) before adjustment. Three-dimensional Convert to monochrome output data (Pr, Pg, Pb (ob)) Three-dimensional Based on the monochromatic output data (Pr, Pg, Pb (ob)), a monochromatic chart is output on an output medium, and the monochromatic chart Three-dimensional A second step for obtaining monochromatic measurement values (Dr, Dg, Db (ob));
Using the reference output characteristic data (β ″ (m)), the same Three-dimensional The reference monochrome input data (R, G, B (m)) and Three-dimensional Same for the monochrome input data (R, G, B (ob)) Three-dimensional The reference monochromatic measurements (Dr, Dg, Db (m)) and Three-dimensional Obtained in the second step in order to correspond the monochromatic measurement values (Dr, Dg, Db (ob)). Three-dimensional The monochromatic measurement values (Dr, Dg, Db (ob)) were obtained in the first step. Three-dimensional Of the target output device (12) as the reference monochromatic measurement values (Dr, Dg, Db (ob)) Three-dimensional A third step for obtaining the monochrome output data (Pr, Pg, Pb (ob));
Three-dimensional The monochrome input data (R, G, B (ob)) was obtained in the third step. Three-dimensional A fourth step for obtaining output adjustment data (θ (ob)) for matching the single color to be converted into the single color output data (Pr, Pg, Pb (ob));
In the target output device (12), Three-dimensional Input data (R, G, B (ob)) is obtained from the output adjustment data (θ (ob)) obtained in the fourth step. Three-dimensional Converted into output data (Pr, Pg, Pb (ob)) Three-dimensional Based on the output data (Pr, Pg, Pb (ob)), a gray balance setting chart including a gray region is output on the output medium, and the gray balance setting chart Three-dimensional Measure the measured values (X, Y, Z) Three-dimensional The input data (R, G, B (ob)) Three-dimensional A fifth step for obtaining a conversion table (g) to be converted into the measured values (X, Y, Z);
The conversion table (g) obtained in the fifth step is subjected to inverse conversion processing using an iterative calculation method, so that the gray color Three-dimensional The measured values (X, Y, Z) Three-dimensional Inverse conversion table (g) for converting the input data (R, G, B (ob)) ^-1 ) For the sixth step,
The reverse conversion table (g ^-1 ) To correct the output adjustment data (θ (ob)) obtained in the fourth step to form a gray color Three-dimensional Input data (R, G, B (ob)) can be obtained in a desired gray color Three-dimensional A seventh step for obtaining output adjustment data (θ (ob)) to be converted into output control data (Pr, Pg, Pb (ob));
It is characterized by comprising.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a configuration to which the gray balance setting method of this embodiment is applied. This configuration is supplied from the reference output device 10 in which the gray balance is set with high accuracy and the reference output device 10. Reference output adjustment data and reference output The target output device 12 is configured to set the gray balance according to the characteristic data. In this case, the target output device 12 has the same configuration as that of the reference output device 10 as a configuration for forming an image, and only a characteristic as an individual difference is different. The recording medium F used in the target output device 12 has substantially the same characteristics as the recording medium used in the reference output device 10.
[0013]
When the target output device 12 is supplied with image data C, M, Y, K consisting of C (cyan), M (magenta), Y (yellow), K (black), the image data C, A processor 14 that performs predetermined image processing on M, Y, and K and converts them into R (red), G (green), and B (blue) device data R, G, and B, and the device data R, G , B for laser recording No An output device 16 that converts the laser power data Pr, Pg, Pb and controls the laser using the laser power data Pr, Pg, Pb to form an image on the recording medium F; A measurement device 18 that obtains a colorimetric value by measuring an image (chart), and is supplied from the colorimetric value and reference output device 10. Reference output adjustment data and reference output It is basically composed of a gray balance setting unit 20 that sets the gray balance of the target output device 12 based on the characteristic data.
[0014]
The processor 14 may convert the image data C, M, and Y into device data R, G, and B, and the colorimetric value L ^* , A ^* , B ^* May be converted into device data R, G, and B. Furthermore, the colorimetric value L is temporarily obtained from the image data C, M, Y, and K. ^* , A ^* , B ^* Then, desired image processing may be performed, and then converted into device data R, G, and B.
[0015]
The apparatus configuration to which the gray balance setting method of the present embodiment is applied is basically as described above. Next, the gray balance setting method in the target output apparatus 12 in this configuration is shown in FIG. This will be described based on a flowchart. Steps SA1 to SA4 represent processing in the reference output device 10, and steps Sa1 to Sa6 represent processing in the target output device 12.
[0016]
First, the gray balance is set in the reference output device 10 (step SA1). This method will be described in the following procedures [1] to [3]. It should be noted that the gray balance setting method in the reference output device 10 can be performed by any method regardless of the procedures [1] to [3].
[0017]
[1] Considering the output characteristics of the reference output device 10 prior to setting the gray balance Standard Create output adjustment data. this Standard Output adjustment data is given device data R, G, B (Standard input data) Desired laser power data Pr, Pg, Pb (Standard output data) FIG. 3 shows the creation procedure.
[0018]
First, linear output adjustment data a1 in which the relationship between laser power data Pr, Pg, and Pb with respect to device data R, G, and B is linear is set (step S1, FIG. 4). Note that the linear output adjustment data a1 is a full-range laser power data Pr with respect to full-range device data R, G, and B (for example, a range of 0 to 255 using the device data R, G, and B as 8-bit data). , Pg, and Pb (for example, the range of 0 to 4095 using the laser power data Pr, Pg, and Pb as 12-bit data).
[0019]
Next, the device data R, G, B is converted into laser power data Pr, Pg, Pb using the linear output adjustment data a1. Then, a test chart is created on the recording medium based on the laser power data Pr, Pg, Pb (step S2).
[0020]
Each patch constituting the test chart is obtained by measuring the density Dr, Dg, Db (or colorimetric values X, Y, Z) of R, G, B by a measuring instrument, thereby obtaining test chart measurement data a2. (Step S3, FIG. 4). Next, the maximum value Dmax and the minimum value Dmin are determined for each of the R, G, and B channels from the test chart measurement data a2. In this case, from the maximum value Dmax and the minimum value Dmin, the maximum value Pmax and the minimum value Pmin of the laser power data Pr, Pg, Pb, which is the dynamic range of the reference output device 10, are determined for each channel of R, G, B. can get.
[0021]
Therefore, the linear output adjustment data a1 is corrected using the maximum value Pmax and the minimum value Pmin to obtain corrected linear output adjustment data a3 (step S4).
[0022]
Next, the device data R, G, and B are converted into laser power data Pr, Pg, and Pb using the modified linear output adjustment data a3. Based on the laser power data Pr, Pg, and Pb, a test chart is created again on the recording medium (step S5).
[0023]
The test chart is obtained by measuring the lightness Lr of R, G, and B with a measuring instrument. ^* , Lg ^* , Lb ^* (Or concentration) is measured, and test chart measurement data a4 is obtained (step S6, FIG. 5). In this case, the test chart measurement data a4 is non-linear and inappropriate for the gray balance calculation method described later, and therefore, the corrected output adjustment data a6 that can be used as the linear characteristic a5 is calculated (step) S7, FIG. 5).
[0024]
The corrected output adjustment data a6 set as described above has a lightness Lr with respect to linear device data R, G, and B within the dynamic range of the reference output device 10. ^* , Lg ^* , Lb ^* It is stored in the reference output device 10 as output adjustment data capable of obtaining an output in which the (or density) is linear (step S8).
[0025]
[2] Using the corrected output adjustment data a6 created as described above, a provisional gray balance that is a rough gray balance is set. FIG. 6 is a flowchart showing the provisional gray balance setting procedure.
[0026]
First, the corrected output adjustment data a6 created in [1] is set in the reference output device 10 (step S10), and the device data R, G, B are used as the laser power data Pr, Pg using the corrected output adjustment data a6. , Pb. Then, a provisional gray balance setting chart is created on the recording medium based on the laser power data Pr, Pg, and Pb (step S11). In this provisional gray balance setting chart, each combination of device data R, G, B (for example, R, G, B = 0, 50, 100, 150, 200, 250, etc.) with a rough data interval is used. It is a gray balance setting chart based.
[0027]
In the provisional gray balance setting chart, the colorimetric values X, Y, and Z are measured by a measuring instrument (step S12). In this case, the provisional gray balance setting chart output on the recording medium corresponds to the color measurement point on the black point within the range indicated by the oblique lines in FIG. 7 of the RGB actual color space.
[0028]
Therefore, further, virtual device data Ri, Gi, Bi are set at positions far away from the range (step S13), and virtual colorimetric values Xi, Yi, Zi corresponding to the virtual device data Ri, Gi, Bi are set. Is obtained (step S14). In this case, the relationship between the virtual device data Ri, Gi, Bi and the virtual colorimetric values Xi, Yi, Zi is the same as the relationship between the device data R, G, B and the colorimetric values X, Y, Z. On the other hand, the virtual colorimetric values Xi, Yi, and Zi are obtained using the least square method, assuming that they have monotonicity. The above assumption of “monotonicity” is guaranteed based on the fact that the brightness of the chart created on the recording medium monotonously decreases or increases as the device data R, G, B increases. The
[0029]
Therefore, all data sets (Rk, Gk, Bk, Xk, Yk, Zk) comprising device data including virtual device data Ri, Gi, Bi and colorimetric values including virtual colorimetric values Xi, Yi, Zi. A four-dimensional plane of X-RGB, Y-RGB, and Z-RGB is obtained by the least square method using (k is the number of each data). In this case, the four-dimensional plane is
T = A · D (1)
It is defined as In addition, the said (1) Formula shall represent the relationship of the following (2) Formula.
[0030]
[Expression 1]

[0031]
Then, the coefficient A satisfying the relationship of the expression (1) is obtained by using the method of least squares so that E shown in the following expression (3) is minimized. In equation (3), k represents the number of each data, and the superscript T represents transposition in which the rows and columns of the matrix are interchanged.
[0032]
[Expression 2]

[0033]
When the coefficient A is obtained from the equation (3), each four-dimensional plane is determined. Next, on the four-dimensional planes X-RGB, Y-RGB, and Z-RGB determined in this manner, virtual device data Ri, Gi, Bi and the like that are sufficiently away from the device data R, G, B, and The corresponding virtual colorimetric values Xi, Yi, Zi are obtained.
[0034]
FIG. 8 is a two-dimensional schematic diagram showing the relationship between device data R, G, B and virtual device data Ri, Gi, Bi and colorimetric values X, Y, Z and virtual colorimetric values Xi, Yi, Zi. It is shown. That is, the relationship between the device data R, G, B obtained from the provisional gray balance setting chart formed on the recording medium and the colorimetric values X, Y, Z is, for example, from points b1 to b4 based on the above-described knowledge. As shown, there is a monotonous decrease relationship. When a four-dimensional plane calculated by the least square method using these points b1 to b4 is indicated by a dotted line, virtual colorimetric values Xi corresponding to the virtual device data Ri, Gi, Bi on the four-dimensional plane, A plane connecting the points d1 and d2 representing Yi and Zi and the points b1 to b4 has a monotonously decreasing relationship as indicated by a solid line. Therefore, device data including virtual device data Ri, Gi, Bi is generated by generating virtual colorimetric values Xi, Yi, Zi for virtual device data Ri, Gi, Bi using the least square method as described above. A monotonous relationship can be maintained between R, G, and B and the colorimetric values X, Y, and Z including the virtual colorimetric values Xi, Yi, and Zi.
[0035]
After the virtual colorimetric values Xi, Yi, and Zi for the virtual device data Ri, Gi, and Bi are obtained as described above, the device data R, G, and B including the virtual device data Ri, Gi, and Bi are converted into the virtual measurement values. A conversion table g that converts colorimetric values X, Y, and Z including color values Xi, Yi, and Zi is set. This conversion relationship is
XYZ = g (RGB) (4)
It shall be written as Next, using the conversion table g, an inverse conversion table for converting the colorimetric values X, Y, and Z into device data R, G, and B by an iterative calculation method such as Newton-Raphson method or data linear interpolation method. g ^-1 Is obtained (step S15).
[0036]
FIG. 9 shows the reverse conversion table g ^-1 It is a flowchart of the process which calculates | requires. Therefore, since gray balance is calculated, L ^* a ^* b ^* A in space ^* = B ^* Target value for gray (L ^* , 0,0) as the target value in the XYZ space (X0, Y0, Z0), and the allowable error in the iterative calculation is _min (Step S20). Next, known initial values (R1, G1, B1) in the RGB space are set (step S21), and the colorimetric values (X1, Y1) for the initial values (R1, G1, B1) are used using the table g. , Z1) is obtained (step S22). Then, an error amount ΔE between the target value (X0, Y0, Z0) and the colorimetric value (X1, Y1, Z1) is obtained (step S23), and the error amount ΔE and the allowable error ΔE are obtained. _min Are compared (step S24). In this case, | ΔE | <ΔE _min Otherwise, the correction values (ΔR, ΔG, ΔB) are calculated (step S25), and the initial values (R1, G1, B1) are corrected by the correction values (ΔR, ΔG, ΔB) (step S26). The processes in steps S22 to S24 are repeated.
[0037]
Here, the correction values (ΔR, ΔG, ΔB) are obtained as follows. That is, as shown in FIG. 10, when arbitrary device data R, G, B is given, the colorimetric values X, Y, Z for the device data R, G, B (indicated by point c) are 8 Device data (R) at two lattice points c0 to c7 ₀ , G ₀ , B ₀ ) ~ (R ₇ , G ₇ , B ₇ ) Colorimetric value (X ₀ , Y ₀ , Z ₀ ) To (X ₇ , Y ₇ , Z ₇ ), Using a volume V of a rectangular parallelepiped surrounded by lattice points c0 to c7, and a volume V0 to V7 divided into eight by an arbitrary interpolation point c in the rectangular parallelepiped,
[0038]
[Equation 3]

[0039]
Can be obtained as In this case, assuming that the colorimetric values X, Y, and Z for the device data R, G, and B are linear within a minute range in the relationship of the expressions (5) to (7), the device data R, G The correction values (ΔR, ΔG, ΔB), which are minute change amounts of B, and the minute change amounts (ΔX, ΔY, ΔZ) of the colorimetric values X, Y, Z are:
[0040]
[Expression 4]

[0041]
Will satisfy the relationship. J is a Jacobian matrix. If the Jacobian matrix J is obtained in the equation (8), the minute change amounts (ΔX, ΔY, ΔZ) of the colorimetric values X, Y, Z with respect to the correction values (ΔR, ΔG, ΔB) of the device data R, G, B are obtained. ) Can be predicted. In this case, the Jacobian matrix J is obtained by partial differentiation of the equations (5) to (7) with the device data R, G, and B. Therefore, the correction values (ΔR, ΔG, ΔB) of the device data R, G, B are
[0042]
[Equation 5]

[0043]
As required.
[0044]
By performing iterative calculation using the Jacobian matrix J obtained as described above, an inverse conversion table g representing the relationship of device data R, G, B with respect to arbitrary gray target values X0, Y0, Z0. ^-1 Can be requested. The reverse conversion table g ^-1 L ^* a ^* b ^* Target value L of space ^* , 0, 0 can also be obtained as a relationship of device data R, G, B.
[0045]
Here, in the Newton-Raphson method, an equation having a solution to be obtained needs to be a monotone function as a convergence condition. In this case, a monotone relationship is established between the device data R, G, B including the virtual device data Ri, Gi, Bi and the colorimetric values X, Y, Z including the virtual colorimetric values Xi, Yi, Zi. In addition, the device space and the colorimetric value space are expanded to the virtual space, and all device data R, G, B and colorimetric values X, Y, Z calculated during the repeated calculation exist. Therefore, it is possible to reliably perform the calculation without divergence and obtain an accurate value.
[0046]
In applying the Newton-Raphson method, in this embodiment, as shown in FIG. 5, the corrected output adjustment is performed so that the characteristic of the provisional gray balance setting chart obtained from the device data R, G, B becomes the linear characteristic a5. Data a6 is set. In this case, since the relationship between the colorimetric values X, Y, and Z with respect to the device data R, G, and B is linear, an operation with less error can be performed compared to the non-linear test chart measurement data a4. That is, when the test chart measurement data a4 is used, the lightness L with respect to changes in the device data R, G, B ^* May increase depending on the device data R, G, and B (see FIG. 5), and an error is likely to occur accordingly. However, when the linear characteristic a5 is used, the brightness L ^* This is because the amount of change can be made substantially constant over the entire range in comparison with the above case, and stable calculation is possible.
[0047]
Inverse conversion table g obtained as described above ^-1 As shown in FIG. 11, the data that constitutes the lightness L ^* (A ^* = B ^* = 0) and device data R, G, B, which are set as provisional gray balance (step S16, FIG. 6).
[0048]
[3] The provisional gray balance set as described above is obtained approximately according to the provisional gray balance setting chart set roughly as shown in FIG. It does not constitute a gray balance. Therefore, a chart is output using the provisional gray balance, and an operation for obtaining a final gray balance with higher accuracy is performed using the chart. FIG. 12 is a flowchart showing the final gray balance setting procedure.
[0049]
First, the corrected output adjustment data a6 created in [1] is modified using the provisional gray balance created in [2] (step S30), and a desired lightness L is obtained when R = G = B. ^* The output adjustment data in which the gray balance is temporarily adjusted that can output the gray color having the above is obtained, and the output adjustment data is downloaded to the output adjustment unit 26 (step S31).
[0050]
Next, using the output adjustment data, device data R, G, and B near the gray color including R = G = B are converted into laser power data Pr, Pg, and Pb. Then, based on the laser power data Pr, Pg, Pb, a final gray balance setting chart is created on the recording medium (step S32). This final gray balance setting chart is created from the output adjustment data set based on the provisional gray balance. For example, the final gray balance setting chart is a colorimetric point on a black dot within the range indicated by the diagonal lines in FIG. Corresponding to the color or the color measurement point in the vicinity thereof, it is set at a finer pitch than the provisional gray balance setting chart shown in FIG.
[0051]
Next, the colorimetric values X, Y, and Z of the final gray balance setting chart are measured by a measuring instrument (step S33). Further, virtual device data Ri, Gi, Bi are set at positions sufficiently distant from the range (step S34), and virtual colorimetric values Xi, Yi, Zi corresponding to the virtual device data Ri, Gi, Bi are obtained. (Step S35).
[0052]
In the same manner as in the case of steps S15 and S16 of [2] shown in FIG. 6, the final gray balance capable of obtaining a highly accurate gray color is calculated by performing the processing of steps S36 and S37. . From this final gray balance, the desired brightness L when R = G = B. ^* Output adjustment data in which the gray balance that can output a gray color having a high-precision is adjusted is obtained and stored in the reference output device 10 (step S38).
[0053]
As described above, after obtaining the provisional gray balance using the gray balance setting chart set at a rough pitch in [2], the gray balance setting chart set at a finer pitch near the gray color in [3]. The final gray balance can be obtained at a high speed using a gray balance setting chart having a small number of patches. Further, by further subdividing the pitch of the gray balance setting chart and repeating the process [3], it is possible to set a more accurate gray balance.
[0054]
If there is no problem in the processing time, the provisional gray balance setting chart obtained from the corrected output adjustment data used for obtaining the provisional gray balance in the process [2] is subdivided and set in advance. It is also possible to obtain the final gray balance at once without performing the process [3].
[0055]
The gray balance of the desired target output device 12 is set using the gray balance of the reference output device 10 set by the procedures [1] to [3] described above or any other method. In the following description, (m) is appended to the end of the data as necessary for the data related to the reference output device 10, and (ob) is necessary for the data related to the target output device 12 at the end of the data. ).
[0056]
Therefore, the reference output for converting the device data R, G, B (m) into the laser power data Pr, Pg, Pb (m) from the corrected output adjustment data in which the gray balance of the reference output device 10 is set. Of the device 10 Reference output adjustment Let it be data α (m). In the reference output device 10, Reference output adjustment Using the data α (m), a chart of all color regions in which the vicinity of the gray color is finely set is created on the recording medium (step SA2), and the colorimetric value L ^* , A ^* , B ^* By measuring (m) (step SA3), device data R, G, B (m) and the colorimetric value L ^* , A ^* , B ^* The number representing the relationship with (m) 1 standard output Characteristic data β (m) is obtained.
[0057]
And said Reference output adjustment Data α (m) and the above First reference output From the characteristic data β (m), the laser power data Pr, Pg, Pb (m) and the colorimetric value L ^* , A ^* , B ^* No. showing the relationship with (m) 2 standard output Characteristic data γ (m) is obtained (step SA4). these Reference output adjustment Data α (m), First reference output characteristic data β (m) and Second reference output characteristic data γ (m) is supplied to the gray balance setting unit 20 of the target output device 12.
[0058]
Next, in the desired target output device 12, device data R, G, B (R = G = B) that should form a gray color using the output adjustment data δ (ob) before adjustment of the output device 16 (Ob) (see data a in FIG. 14) is converted into laser power data Pr, Pg, Pb (ob) (see data b in FIG. 14), and based on the laser power data Pr, Pg, Pb (ob). A chart is created on the recording medium F (step Sa1).
[0059]
The chart is measured by the measuring instrument 18, and the colorimetric value L ^* , A ^* , B ^* (Ob) is obtained (see step Sa2, data c in FIG. 14). The laser power data Pr, Pg, Pb (ob) (see data b in FIG. 14) and the colorimetric value L of the target output device 12 ^* , A ^* , B ^* (Ob) the relationship with (see data c in FIG. 14) output Characteristic data ε (ob) Reference output adjustment Data α (m), Second reference output characteristic data γ (m), Output adjustment data δ (ob), Output characteristic data FIG. 14 shows the relationship of ε (ob).
[0060]
In this case, the colorimetric value L ^* , A ^* , B ^* (Ob) is a desired value corresponding to the gray color (see data c in FIG. 14), that is, a ^* = B ^* If so, since the target output device 12 is in gray balance, the output adjustment data δ (ob) is set in the output machine 16 of the target output device 12 as gray balance output adjustment data. (Step Sa3).
[0061]
On the other hand, when the gray balance is not achieved, the colorimetric value L ^* , A ^* , B ^* (Ob) The laser power data Pr, Pg, Pb (m) of the reference output device 10 corresponding to (data c in FIG. 14) 2 standard output It is obtained using the characteristic data γ (m) (see step Sa4, data d in FIG. 14).
[0062]
The colorimetric value L ^* , A ^* , B ^* The relationship of the laser power data Pr, Pg, Pb (m) with respect to (m) can be obtained using the Newton-Raphson method described above or any other method. The first 2 standard output Instead of using the characteristic data γ (m), 1 standard output Using the characteristic data β (m), the colorimetric value L ^* , A ^* , B ^* After determining the relationship of the device data R, G, B (m) with respect to (m) by the Newton-Raphson method or the like, Reference output adjustment By obtaining the laser power data Pr, Pg, Pb (m) using the data α (m), as a result, the colorimetric value L ^* , A ^* , B ^* The relationship of the laser power data Pr, Pg, Pb (m) to (m) may be obtained.
[0063]
Next, the laser power data Pr, Pg, Pb (m) when the device data R, G, B (R = G = B) (ob) (data a in FIG. 14) is given to the reference output device 10 ( The data e) in FIG. Reference output adjustment Data α (m) is used to obtain difference data (ed) between the data d and e (step Sa5).
[0064]
Finally, using the difference data (ed), laser power data Pr for the device data R, G, B (R = G = B) (ob) (data a in FIG. 14) of the target output device 12 , Pg, Pb (ob) (see data f in FIG. 14, fb = ed) Ru Thus, the corrected output adjustment data θ (ob) is obtained (step Sa6).
[0065]
The output adjustment data θ (ob) is obtained not by using the difference data (ed), but by obtaining the ratio data e / d between the data d and the data e, and the ratio data e / d is converted into the data b. It can also be obtained by multiplication.
[0066]
After obtaining the output adjustment data θ (ob) as described above, the laser power data is again obtained from the device data R, G, B (R = G = B) (ob) using the output adjustment data θ (ob). Pr, Pg, and Pb (ob) are obtained, and a chart is created based on the laser power data Pr, Pg, and Pb (ob). This process is performed with a colorimetric value L to be a desired gray color. ^* , A ^* , B ^* By repeating until (ob) is obtained, output adjustment data θ capable of setting a highly accurate gray balance for the target output device 12 is obtained.
[0067]
In this way, the target output device 12 outputs the minimum necessary chart using the device data R, G, B (R = G = B) that should be gray, and then easily and quickly the gray balance. Can be set. In the above-described embodiment, the colorimetric value L of the chart ^* , A ^* , B ^* The gray balance is set by obtaining the above, but the gray integrated density may be obtained in advance.
[0068]
In the target output device 12 of the present embodiment, image conversion processing is performed using the output adjustment data θ set as described above.
That is, the image data C, M, Y, and K supplied to the processor 14 are converted into device data R, G, and B, and then transferred to the output device 16, and the device data R, G, and B are output as the output data. The adjustment data θ is converted into laser power data Pr, Pg, and Pb. Next, the laser is controlled based on the laser power data Pr, Pg, Pb, and a desired image is formed on the recording medium F. In this case, the gray balance and gradation of the image are adjusted with high accuracy, and a desired color is reproduced.
[0069]
Note that, as described above, the gray balance is fed back to the processor 14 instead of being adjusted in the output adjustment data θ of the output device 16, for example, the colorimetric value L as device data. ^* , A ^* , B ^* To gray balance De It is also possible to set so that vise data R, G, B can be obtained.
[0070]
Next, another embodiment for setting the gray balance for the target output device 12 will be described based on the flowchart shown in FIG.
[0071]
In this case, first, the gray balance is set in the reference output device 10 by performing the processes [1] to [3] described above on the reference output device 10 (step SB1).
[0072]
Next, in the reference output device 10, from the device data R, G, B (m) (R = G = B) Reference output adjustment Laser power data Pr, Pg, Pb (m) is generated using the data α (m), and a gray chart is formed on the recording medium based on the laser power data Pr, Pg, Pb (m) ( Step SB2). By measuring the density values Dr, Dg, Db (m) of the chart (step SB3), the relationship between the device data R, G, B (m) and the density values Dr, Dg, Db (m) is expressed. As the gray target gradation data 1 standard output Characteristic data β ′ (m) is obtained.
[0073]
And said Reference output adjustment Data α (m) and the above 1 standard output From the characteristic data β ′ (m), the relationship between the laser power data Pr, Pg, Pb (m) and the density values Dr, Dg, Db (m) is shown. 2 standard output Characteristic data γ ′ (m) is obtained (step SB4). these Reference output adjustment Data α (m), First reference output characteristic data β ′ (m) and Second reference output characteristic data γ ′ (m) is supplied to the gray balance setting unit 20 of the target output device 12.
[0074]
Next, the desired target output device 12 outputs a chart based on device data R, G, B (ob) (R = G = B) that should be gray, and the density values Dr, Dg, Db ( Ob) is measured. Then, output adjustment data in which gray balance is achieved is obtained in substantially the same manner as the processing of steps Sa1 to Sa6 described above (step Sb1).
[0075]
The relationship of the laser power data Pr, Pg, Pb (m) with respect to the concentration values Dr, Dg, Db (m) can be obtained using the Newton-Raphson method described above or any other method. Since the relationship between these data is a one-dimensional correspondence, it can be easily obtained using any other method. Further, instead of using the second characteristic data γ ′ (m), the second characteristic data γ ′ (m) 1 After obtaining the relationship of the device data R, G, B (m) to the density values Dr, Dg, Db (m) using the characteristic data β ′ (m), Reference output adjustment By obtaining the laser power data Pr, Pg, Pb (m) using the data α (m), as a result, the laser power data Pr, Pg, Pb corresponding to the density values Dr, Dg, Db (m). The relationship (m) may be obtained. Furthermore, in this embodiment, the gray balance is set by obtaining the density values Dr, Dg, and Db of the chart. However, the gray balance may be set from the colorimetric values of the chart.
[0076]
Here, in the above-described embodiment, in the reference output device 10 Reference output adjustment Data α (m), First reference output characteristic data β ′ (m), Second reference output characteristic data γ '(m), or Reference output adjustment Data α (m), First reference output characteristic data β ′ (m) is used to obtain output adjustment data in which gray balance is achieved, and represents the relationship of density values Dr, Dg, Db (m) with respect to device data R, G, B (m). Said 1 standard output The output adjustment data can be obtained using only the characteristic data β ′ (m).
[0077]
That is, after the second characteristic data β ′ (m) of the reference output device 10 obtained in step SB3 is supplied to the gray balance setting unit 20 of the target output device 12, the target output device 12 becomes a gray color. A chart is output based on the device data R, G, B (ob) (R = G = B), and the density values Dr, Dg, Db (ob) are measured. Next, the density values Dr, Dg, Db (ob) and the density values Dr, Dg, Db (m) for the same device data R, G, B (R = G = B) are made to correspond to each other, and the density values Dr, Dg, Laser power data Pr, Pg, Pb (ob) in the target output device 12 capable of obtaining Db (m) is set for the device data R, G, B (ob) (R = G = B). Thus, output adjustment data can be obtained.
[0078]
Next, still another embodiment for setting the gray balance for the target output device 12 will be described based on the flowchart shown in FIG. 16 and FIG.
[0079]
In this case, first, the gray balance is set in the reference output device 10 by performing the processes [1] to [3] described above on the reference output device 10 (step SC1).
[0080]
Next, from the device data R, G, B (m) in the reference output device 10 Reference output adjustment Laser power data Pr, Pg, Pb (m) is generated using data α (m), and monochrome charts of C, M, Y are recorded on the recording medium based on the laser power data Pr, Pg, Pb (m). (Step SC2). Then, by measuring the density values Dr, Dg, Db (m) of the monochrome chart (step SC3), the device data R, G, B (m) and the density values Dr, Dg, Db (m) As the monochrome target gradation data representing the relationship 1 standard output Characteristic data β ″ (m) is obtained. And said Reference output adjustment Data α (m) and the above 1 standard output From the characteristic data β ″ (m), the relationship between the laser power data Pr, Pg, Pb (m) and the density values Dr, Dg, Db (m) is shown. 2 standard output Characteristic data γ ″ (m) is obtained (step SC4). these Reference output adjustment Data α (m), First reference output characteristic data β ″ (m) and Second reference output characteristic data γ ″ (m) is supplied to the gray balance setting unit 20 of the target output device 12.
[0081]
Next, the desired target output device 12 outputs a monochromatic chart based on the device data R, G, B (ob) (see data g in FIG. 17) that should be a desired monochromatic color (step Sc1), and the density The values Dr, Dg, Db (ob) are measured (see step Sc2, data h in FIG. 17). Further, the density values Dr, Dg, Db (m) (see data i in FIG. 17) obtained when the device data R, G, B (ob) (data g) are given to the standard output device 10 are output as the standard. Of the device 10 Reference output adjustment Data α (m) and Second reference output characteristic data It calculates | requires using (gamma) '' (m) (step Sc3).
[0082]
Here, when the density values Dr, Dg, Db (ob) (data h) and the density values Dr, Dg, Db (m) (data i) do not match (step Sc4), the density values Dr, Dg, Laser power data Pr, Pg, and Pb (ob) (see data j in FIG. 17) for Db (ob) (data i) are obtained. The relationship between the laser power data Pr, Pg, Pb (ob) (data j) and the device data R, G, B (ob) (data g) matches the single color output by the reference output device 10. The output adjustment data θ (ob) in the target output device 12 that can obtain the obtained single color is obtained (step Sc5).
[0083]
In addition, the accuracy of the single color in the target output device 12 can be improved by repeating the processes of steps Sc1 to Sc5 using the output adjustment data θ (ob) set as described above.
[0084]
After the single color is adjusted as described above (step Sc4), the target output device 12 performs a gray balance setting process in substantially the same manner as in step SC1 (step Sc6). In this case, since the single color has already been adjusted, the output adjustment data set in the target output device 12 can be regarded as the provisional gray balance described in the flowchart shown in FIG. Therefore, the target output device 12 can quickly obtain the final gray balance shown in FIG.
[0085]
【The invention's effect】
As described above, in the present invention, it is possible to easily set a highly accurate gray balance in the target output device, and to reproduce the color of an image with high accuracy using the output adjustment data in which the gray balance is set. Can do.
[0086]
In addition, using the relationship between the device data in the reference output device for which the gray balance has already been set and the measured values of the chart output based on the device data, the gray balance of the numerous target output devices can be set quickly and accurately. can do.
[0087]
Furthermore, the process of setting the gray balance can be automatically performed online.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an apparatus to which a gray balance setting method according to an embodiment is applied.
FIG. 2 is a flowchart showing a gray balance setting method in the target output device.
FIG. 3 is a flowchart showing a procedure for creating output adjustment data in the reference output device of FIG. 1;
4 is an explanatory diagram of a procedure for creating output adjustment data in FIG. 3; FIG.
FIG. 5 is an explanatory diagram of a procedure for creating output adjustment data in FIG. 3;
6 is a flowchart showing a provisional gray balance setting procedure in the reference output device of FIG. 1; FIG.
FIG. 7 is an explanatory diagram of device data including virtual device data.
FIG. 8 is an explanatory diagram of a method for generating virtual device data by the method of least squares.
FIG. 9 is a flowchart of device data calculation processing by the Newton-Raphson method.
FIG. 10 is an explanatory diagram of volume interpolation.
FIG. 11 is an explanatory diagram of gray balance.
12 is a flowchart showing a final gray balance setting procedure in the reference output device of FIG. 1; FIG.
FIG. 13 is an explanatory diagram of device data including virtual device data obtained from provisional gray balance.
FIG. 14 is an explanatory diagram of a gray balance setting method in the target output device.
FIG. 15 is a flowchart showing another embodiment of a gray balance setting method in the target output device.
FIG. 16 is a flowchart showing still another embodiment of a gray balance setting method in the target output device.
FIG. 17 is an explanatory diagram of a gray balance setting method in the target output device.
[Explanation of symbols]
10 ... Standard output device 12 ... Target output device
14 ... Processor 16 ... Output machine
18 ... Measuring device 20 ... Gray balance setting section

Claims (7)

Using the set reference output device of the reference output adjustment data gray balance is adjusted, into a three-dimensional reference output data three-dimensional reference data input by said reference output adjustment data, the reference output of the three-dimensional outputs the reference chart on an output medium based on the data, the first reference output characteristic of the reference output device for converting the three-dimensional reference measurements obtained by measuring the reference chart on the three-dimensional of the reference input data data, or a first step of obtaining a second reference output characteristic data of the reference output device for converting the reference measurement of the three-dimensional three-dimensional of the reference output data,
Using the target output device having the same configuration as the reference output device for setting the gray balance, the three-dimensional gray input data forming the gray color is converted into the three- dimensional gray output data by the output adjustment data before adjustment, A second step of outputting a gray chart on an output medium based on the original gray output data and measuring the gray chart to obtain a three-dimensional gray measurement value;
The three-dimensional reference output data in the reference output device capable of obtaining the three-dimensional gray measurement value obtained in the second step is the first reference output characteristic data and the reference output adjustment data, or the first A third step to obtain using the two reference output characteristic data;
A fourth step of determining, using the reference output adjustment data, the three-dimensional reference output data of the reference output device corresponding to the three-dimensional gray input data;
Said reference output data of the three-dimensional obtained in the third step, the determined correction data for correcting the three-dimensional of the reference output data obtained in the fourth step, the gray output data of the three-dimensional by the correction data corrected, a fifth step of obtaining an output adjustment data for converting the gray input data of the three-dimensional corrected three-dimensional the gray output data,
A gray balance setting method characterized by comprising: The method of claim 1, wherein
The gray balance setting method, wherein the output adjustment data before the adjustment in the second step is replaced with the output adjustment data obtained in the fifth step, and the processing from the second step is repeated. The method of claim 1, wherein
The gray balance setting method, wherein the reference measurement value and the gray measurement value are three-dimensional colorimetric values. The method of claim 1, wherein
The gray balance setting method, wherein the reference chart output in the first step is a chart of all color regions. The method of claim 1, wherein
The gray balance setting method, wherein the reference chart output in the first step is a gray chart. Using the set reference output device of the reference output adjustment data gray balance is adjusted, into a three-dimensional reference gray output data a three dimensional reference gray input data by the reference output adjustment data, the three-dimensional reference outputs the reference gray chart on an output medium based on the gray output data, the reference output for converting the three-dimensional reference gray measurements obtained by measuring the reference gray chart on the three-dimensional of the reference gray input data the first reference output characteristic data of the device or, a first step of obtaining a second reference output characteristic data of the reference output device for converting the reference gray measurement of three-dimensional three-dimensional to the reference gray output data,
Using the target output device having the same configuration as the reference output device for setting the gray balance, the three-dimensional gray input data forming the gray color is converted into the three- dimensional gray output data by the output adjustment data before adjustment, A second step of outputting a gray chart on an output medium based on the original gray output data and measuring the gray chart to obtain a three-dimensional gray measurement value;
Using the first reference output characteristic data and the reference output adjustment data, or the second reference output characteristic data, the same three-dimensional reference gray input data and three-dimensional gray input data are the same. in order to correspond to the gray measured value of the reference gray measurements of three-dimensional and three-dimensional, the target output of the reference gray measurement of three-dimensional the gray measurement of three-dimensional obtained in the second step A third step for determining the three-dimensional gray output data of the device;
A fourth step of obtaining output adjustment data for converting the three-dimensional gray input data into the three-dimensional gray output data obtained in the third step;
A gray balance setting method characterized by comprising: Using the set reference output device of the reference output adjustment data gray balance is adjusted to convert the reference monochromatic input data of the three-dimensional reference monochromatic output data of the three-dimensional by the reference output adjustment data, the three-dimensional based on the reference monochromatic output data to output the reference monochromatic chart on an output medium, the reference output for converting the reference monochromatic measurement of three-dimensional obtained by measuring the reference monochromatic chart in three dimensions of the reference monochromatic input data A first step for obtaining reference output characteristic data of the device;
Using a target output device having the same configuration as the reference output device for setting the gray balance, three-dimensional single-color input data forming a desired single color is converted into three-dimensional single-color output data by output adjustment data before adjustment, A second step of outputting a monochromatic chart on an output medium based on the three-dimensional monochromatic output data and obtaining a three-dimensional monochromatic measurement of the monochromatic chart;
Using the reference output characteristic data, the same three-dimensional reference monochromatic input data and the three-dimensional monochromatic input data are obtained by using the same three-dimensional reference monochromatic measurement value and the three-dimensional monochromatic measurement value. in order to correspond, obtains the monochrome output data of the three-dimensional of the target output device to the reference monochromatic measurement of three-dimensional found the monochromatic measurement of three-dimensional obtained in the second step in the first step The third step;
A fourth step for obtaining output adjustment data for matching the single color to be converted into the three-dimensional monochromatic output data obtained in the third step, and the three-dimensional monochromatic input data;
In the target output device, into a three-dimensional output data by the output adjustment data obtained input data of the three-dimensional in the fourth step includes a gray area on the output medium on the basis of the three-dimensional of the output data a fifth step of outputting the gray balance setting chart, finding a conversion table wherein measuring the measurements of the three-dimensional gray balance setting chart, to convert the input data of the three-dimensional on the measured value of the three-dimensional,
A sixth step for obtaining an inverse conversion table for converting the gray three-dimensional measurement value into the three-dimensional input data by performing an inverse conversion process on the conversion table obtained in the fifth step using an iterative calculation method. When,
The output adjustment data obtained in the fourth step is corrected using the inverse conversion table, and the three-dimensional input data for forming a gray color is changed to three- dimensional output control data capable of obtaining a desired gray color. A seventh step for obtaining output adjustment data to be converted;
A gray balance setting method characterized by comprising:

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