JP2004274268A - Color conversion operator generation apparatus, method, program, recording medium, and projector - Google Patents

Abstract

An object of the present invention is to provide a color conversion operator generation device capable of appropriately reproducing colors even when the surrounding environment changes.
According to a conversion operator generation unit of the present invention, a change in the appearance of a projected image on a projection plane due to a change in an ambient environment is corrected by a color conversion operator. First, the parameter calculating unit 130 calculates a parameter α indicating a contrast effect between the projected image and the color of the projected surface based on the information on the appearance of the projected image in the projection area on the projection surface, and the conversion matrix combining unit 100a Based on the calculated parameter α, a color conversion operator for correcting a change in the appearance of the projected image on the projection plane due to a change in the surrounding environment is generated.
[Selection] Fig. 2

Description

に基づき、基準環境下における変換行列Ｍ_ｄ０を生成する（Ｓ５４）。
【００４１】
ここで、
【００４２】
【数２】

であり、
ｘ_Ｒｄ０＝Ｘ_Ｒｄ０／（Ｘ_Ｒｄ０＋Ｙ_Ｒｄ０＋Ｚ_Ｒｄ０）
ｙ_Ｒｄ０＝Ｙ_Ｒｄ０／（Ｘ_Ｒｄ０＋Ｙ_Ｒｄ０＋Ｚ_Ｒｄ０）
ｚ_Ｒｄ０＝Ｚ_Ｒｄ０／（Ｘ_Ｒｄ０＋Ｙ_Ｒｄ０＋Ｚ_Ｒｄ０）
である。なお、
ｘ_Ｇｄ０，ｙ_Ｇｄ０，ｚ_Ｇｄ０，ｘ_Ｂｄ０，ｙ_Ｂｄ０，ｚ_Ｂｄ０についても同様である。
【００４３】
そして、生成された変換行列Ｍ_ｄ０を基準環境データ保存部１００ｂに保存して（Ｓ５６）、図４に示す本処理に移行する。
【００４４】
２−２） 本処理（図４）
次に図４を参照して、本発明に係る色変換演算子を用いての環境補正処理の本処理を説明する。
【００４５】
図４に示す本処理では、事前処理と同様に、まず投影領域１２の特定を行い（Ｓ２０）、使用環境下でのプロジェクタ２０の出力色の測定および変換行列の生成並びに保存を行う（Ｓ２２）。
【００４６】
Ｓ２０における投影領域の特定処理およびＳ２２における使用環境下での色測定および変換行列の生成・保存処理は、それぞれ図６を参照して説明したＳ１０における処理および図５を参照して説明したＳ１２における処理を、基準環境下で行う代わりに使用環境下で行なったものである。
【００４７】
２−２−１） 投影領域の特定（Ｓ２０）
Ｓ２０における投影領域の特定処理は、図６を参照して説明したＳ１０における処理と同様であるので、その説明を省略する。
【００４８】
２−２−２） 使用環境下での色測定および変換行列の生成・保存（Ｓ２２）
次に、事前処理の場合と同様に、図５に示すフローチャートを参照して、図４のＳ２２に示す使用環境下での色測定および変換行列の生成・保存処理について説明する。
【００４９】
まず、使用環境下において、プロジェクタ２０からスクリーン１０に対して黒（Ｋ）を出力し（Ｓ４０）、センサ６０によってスクリーン１０における反射光の三刺激値を測定する（Ｓ４２）。そして、投影領域１２内の値を平均化する（Ｓ４４）。平均化した値をＸ_Ｋ，Ｙ_Ｋ，Ｚ_Ｋとする。ここで、使用環境時の照明の明るさはプロジェクタの黒を投影した場合の輝度Ｙ_Ｋに相当する。
【００５０】
次に、使用環境下において、プロジェクタ２０からスクリーン１０に対して白（Ｗ）、赤（Ｒ）、緑（Ｇ）、青（Ｂ）の何れかを出力し（Ｓ４６）、センサ６０によってスクリーン１０における反射光の三刺激値を測定する（Ｓ４８）。そして、投影領域１２内の値を平均化する（Ｓ５０）。白（Ｗ）、赤（Ｒ）、緑（Ｇ）、青（Ｂ）についての平均化した値を、それぞれ
Ｘ_Ｗ，Ｙ_Ｗ，Ｚ_Ｗ
Ｘ_Ｒ，Ｙ_Ｒ，Ｚ_Ｒ
Ｘ_Ｇ，Ｙ_Ｇ，Ｚ_Ｇ
Ｘ_Ｂ，Ｙ_Ｂ，Ｚ_Ｂ
とする。そして、各色についての測定値から黒についての測定値を減算して正規化する（Ｓ５２）。Ｒの三刺激値の場合
Ｘ_Ｒｄ＝（Ｘ_Ｒ−Ｘ_Ｋ）／（Ｙ_Ｗ−Ｙ_Ｋ）
Ｙ_Ｒｄ＝（Ｙ_Ｒ−Ｙ_Ｋ）／（Ｙ_Ｗ−Ｙ_Ｋ）
Ｚ_Ｒｄ＝（Ｚ_Ｒ−Ｚ_Ｋ）／（Ｙ_Ｗ−Ｙ_Ｋ）
となる。Ｗ、ＧおよびＢについても同様に算出できる。
【００５１】
そして、Ｓ４６〜Ｓ５２の処理をＷ、Ｒ、ＧおよびＢの４色について繰り返えす。なお、当該実施形態では、４色を用いる場合について説明したが、３色でも同様に変換行列Ｍ_ｄ０を生成できる。しかし、４色を用いた場合の方が３色を用いた場合よりも精度が高い。
【００５２】
次に、変換行列Ｍ_ｄ生成部２００ｂは、
【００５３】
【数３】

に基づき、使用環境下における変換行列Ｍ_ｄを生成する（Ｓ５４）。
【００５４】
ここで、
【００５５】
【数４】

であり、
ｘ_Ｒｄ＝Ｘ_Ｒｄ／（Ｘ_Ｒｄ＋Ｙ_Ｒｄ＋Ｚ_Ｒｄ）
ｙ_Ｒｄ＝Ｙ_Ｒｄ／（Ｘ_Ｒｄ＋Ｙ_Ｒｄ＋Ｚ_Ｒｄ）
ｚ_Ｒｄ＝Ｚ_Ｒｄ／（Ｘ_Ｒｄ＋Ｙ_Ｒｄ＋Ｚ_Ｒｄ）
である。なお、
ｘ_Ｇｄ，ｙ_Ｇｄ，ｚ_Ｇｄ，ｘ_Ｂｄ，ｙ_Ｂｄ，ｚ_Ｂｄについても同様である。
【００５６】
そして、生成された変換行列Ｍ_ｄを使用環境データ保存部１００ｃに保存して（Ｓ５６）、図４のＳ２４における処理に移行する。
【００５７】
２−２−３） スクリーン上での照明の明るさ測定処理（Ｓ２４）
部屋の照明がある程度の明るさを有していなければ、投影領域近傍の色も知覚できないので、対比効果は生じない。そこで、照明の明るさ演算部２００ｅが、スクリーン上での照明の明るさを測定する。
【００５８】
図７に、Ｓ２４のスクリーン上での照明の明るさ測定処理を説明するためのフローチャートを示す。
【００５９】
まず、使用環境下において、プロジェクタ２０からスクリーン１０に対して黒（Ｋ）を出力し（Ｓ７０）、センサ６０によってスクリーン１０における反射光を測定する（Ｓ７２）。
【００６０】
具体的には、以下で説明するＹを測定する。プロジェクタから黒を出力したときの投影領域内の明るさは、プロジェクタの黒の輝度が小さければ、スクリーン上の照明の明るさに対応した値とみなすことができる。これをＹとし対比パラメータの算出に用いる。ＹはＳ４４で測定したＹ_Ｋと同じものなので、その値をそのまま用いても良い。
【００６１】
そして、投影領域１２内のＹ値を平均化する（Ｓ７４）。これを数式で具体的に示すと、
Ｙ＝Ｙ_Ｋ＝｛Σ_{（投影領域内）}Ｙ_Ｋ（ｉ，ｊ）｝／Ｎ … （１）
となる。ここで、Ｙ_Ｋ（ｉ，ｊ）は、センサの各画素における測定輝度であり、Ｎは、投影領域内の画素数であり、Σ_{（投影領域内）}は、投影領域内の画素について和を取ることを示す。
【００６２】
Ｓ７４における処理の後、図４のＳ２６における処理に移行する。
【００６３】
２−２−４） スクリーン色の測定処理（Ｓ２６）
投影画像は基準の白色スクリーンに投影したときの色と同じになるように補正されるので、スクリーンの色が白色から大きく外れるほどスクリーンとの対比効果が大きくなる。基準環境下（暗室、白色スクリーン）と使用環境下においてプロジェクタから白を出力したときの色との色度差は、両環境下におけるスクリーン色の差に対応する値とみなすことができる。
【００６４】
図８に、Ｓ２６のスクリーン色の測定処理（スクリーンの色演算部による処理）を説明するためのフローチャートを示す。
【００６５】
まず、使用環境下において、プロジェクタ２０からスクリーン１０に対して白（Ｗ）を出力し（Ｓ８０）、センサ６０によってスクリーン１０における反射光を測定する（Ｓ８２）。そして、Ｓ７４と同様に、投影領域１２内においてＳ８２における測定値を平均化し（Ｓ８４）、色度を算出する（Ｓ８６）。
【００６６】
次に、図３を参照して説明した基準環境下でのプロジェクタの白の測定値をデータ格納部から読み出し（Ｓ８８）、色度を算出する（Ｓ９０）。
【００６７】
そして、Ｓ８６において算出された色度と、Ｓ９０において算出された色度との差を算出する（Ｓ９２）。基準環境下（暗室、白色スクリーン）と使用環境下においてプロジェクタから白を出力したときの色との色度差（両環境下におけるスクリーン色の差に対応する値）をΔとし、対比パラメータの算出に用いる。当該実施形態においては、Δを計算する際の色空間をＹｘｙ表色系とするが、Ｌ＊ａ＊ｂ＊表色系など任意の色空間を用いることができる。Ｙｘｙ表色系を用いた場合のΔは、
Δ＝｛（ｘ_Ｗ−ｘ_Ｗ０）^２＋（ｙ_Ｗ−ｙ_Ｗ０）^２｝^１／２ … （２）
によって算出される。
【００６８】
ここで、
ｘ_Ｗ０＝Ｘ_Ｗ０／（Ｘ_Ｗ０＋Ｙ_Ｗ０＋Ｚ_Ｗ０）
ｙ_Ｗ０＝Ｙ_Ｗ０／（Ｘ_Ｗ０＋Ｙ_Ｗ０＋Ｚ_Ｗ０）
ｘ_Ｗ＝Ｘ_Ｗ／（Ｘ_Ｗ＋Ｙ_Ｗ＋Ｚ_Ｗ）
ｙ_Ｗ＝Ｙ_Ｗ／（Ｘ_Ｗ＋Ｙ_Ｗ＋Ｚ_Ｗ）
である。
【００６９】
Ｘ_Ｗ０，Ｙ_Ｗ０，Ｚ_Ｗ０は、基準環境下におけるプロジェクタの白の三刺激値であり、図３のＳ１２において測定された値である。また、Ｘ_Ｗ，Ｙ_Ｗ，Ｚ_Ｗは、使用環境下におけるプロジェクタの白の三刺激値であり、図４のＳ２２において測定された値である。
【００７０】
上記のように、Δの計算にＹｘｙ表色系を用いた場合、Ｌ＊ａ＊ｂ＊表色系を用いた場合に比べて計算量は少なくなる。しかし、Ｙｘｙ表色系の特性上、広い色域に渡って考えた場合、Δの値が人が見たときに感じる色度差と必ずしも一致しないという欠点がある。したがって、より高い精度が求められる場合には、以下のようにＬ＊ａ＊ｂ＊表色系を用いることが好ましい。Ｌ＊ａ＊ｂ＊表色系を用いる場合のΔは、
Δ＝｛ａ＊_Ｗ ^２＋ｂ＊_Ｗ ^２｝^１／２
によって算出される。
ここで、
ａ＊_Ｗ＝５００［（Ｘ_Ｗ／Ｘ_Ｎ）^１／３−（Ｙ_Ｗ／Ｙ_Ｎ）^１／３］
ｂ＊_Ｗ＝２００［（Ｙ_Ｗ／Ｙ_Ｎ）^１／３−（Ｚ_Ｗ／Ｚ_Ｎ）^１／３］
Ｘ_Ｎ＝Ｘ_Ｗ０ Ｙ_Ｗ／Ｙ_Ｗ０
Ｙ_Ｎ＝Ｙ_Ｗ
Ｚ_Ｎ＝Ｚ_Ｗ０ Ｙ_Ｗ／Ｙ_Ｗ０
である。
【００７１】
Ｓ９２における処理の後、図４のＳ２８における処理に移行する。
【００７２】
２−２−５） 投影領域とスクリーンとの面積比の測定処理（Ｓ２８）
スクリーンの大きさが投影領域よりも広くなければ、スクリーンの色との対比効果は起こらない。そこで、スクリーンサイズ演算部２００ｃが、投影領域近傍で投影領域と近い色をしている領域を検出し、投影領域との面積比を求める。当該面積比をＲとし、対比パラメータの算出に用いる。
【００７３】
図９に、図４のＳ２８における投影領域とスクリーンとの面積比の測定処理を説明するためのフローチャートを示す。
【００７４】
まず、プロジェクタ２０からスクリーン１０に対して黒（Ｋ）を投影して（Ｓ１００）、センサの各画素における色度ｘ_Ｋ（ｉ，ｊ）、ｙ_Ｋ（ｉ，ｊ）を測定する（Ｓ１０２）。ここで、
ｘ_Ｋ（ｉ，ｊ）＝Ｘ_Ｋ（ｉ，ｊ）／｛Ｘ_Ｋ（ｉ，ｊ）＋Ｙ_Ｋ（ｉ，ｊ）＋Ｚ_Ｋ（ｉ，ｊ）｝
ｙ_Ｋ（ｉ，ｊ）＝Ｙ_Ｋ（ｉ，ｊ）／｛Ｘ_Ｋ（ｉ，ｊ）＋Ｙ_Ｋ（ｉ，ｊ）＋Ｚ_Ｋ（ｉ，ｊ）｝
である。ここで、Ｙ_Ｋ（ｉ，ｊ）は、センサの各画素における測定輝度である。
【００７５】
そして、投影領域内の値を平均化して、投影領域内の平均色度ｘ_Ｋ，ｙ_Ｋを求める。これを数式で具体的に示すと、
ｘ_Ｋ＝｛Σ_{（投影領域内）}ｘ_Ｋ（ｉ，ｊ）｝／Ｎ
ｙ_Ｋ＝｛Σ_{（投影領域内）}ｙ_Ｋ（ｉ，ｊ）｝／Ｎ
となる。ここで、Ｎは、投影領域内の画素数であり、Σ_{（投影領域内）}は、投影領域内の画素について和を取ることを示す。
【００７６】
次に投影領域外の各画素について、投影領域内の平均色度との色度差を求め、閾値以内に収まっている画素数をカウントする（Ｓ１０６〜Ｓ１１２）。
【００７７】
すなわち、投影領域外の画素を順に選択し（Ｓ１０６）、投影領域内の平均色度との色度差Ｓ_Ｋ（ｉ，ｊ）を算出し（Ｓ１０８）、Ｓ_Ｋ（ｉ，ｊ）が閾値内であれば、カウンタＮ_Ｓを１加算する（Ｓ１１０）。Ｓ１０６〜Ｓ１１０を全ての画素について繰り返す（Ｓ１１２）。Ｓ１０６〜Ｓ１１２を数式によって表現すると、
Ｓ_Ｋ（ｉ，ｊ）＝１ （｜ｘ_Ｋ（ｉ，ｊ）−ｘ_Ｋ｜≦Δｘかつ｜ｙ_Ｋ（ｉ，ｊ）−ｙ_Ｋ｜≦Δｙのとき）
Ｓ_Ｋ（ｉ，ｊ）＝０ （上記以外の場合）
Ｎ_Ｓ＝Σ_{（投影量域外）}Ｓ（ｉ，ｊ）
となる。ここで、Σ_{（投影領域内外）}は、投影領域内外の画素について和を取ることを示す。なお、閾値ΔｘおよびΔｙは定数であり、０．００５〜０．０５が適当である。
【００７８】
そして、総カウンタ数Ｎ_Ｓ＝Σ_{（投影量域外）}Ｓ（ｉ，ｊ）からスクリーンの大きさを算出し（Ｓ１１４）、次式：
Ｒ＝（Ｎ＋Ｎ_Ｓ）／Ｎ … （３）
によって投影領域とスクリーンとの面積比Ｒを算出する（Ｓ１１６）。
【００７９】
Ｓ１１６における処理の後、図４のＳ３０における処理に移行する。
【００８０】
２−２−６） 対比パラメータαの算出処理（Ｓ３０）
パラメータα生成部１３０は、スクリーン上での照明の明るさＹ、スクリーンの色（基準スクリーンとの色度差）Δおよび投影領域とスクリーンとの面積比Ｒに基づき、対比効果の程度を示すパラメータαを算出する。
【００８１】
図１０に、対比パラメータαの算出処理を説明するための図を示す。
【００８２】
対比パラメータαは、
α＝αｍｉｎ＋（１−αｍｉｎ）×α１×α２×α３ … （４）
によって求められる。入力映像信号に対して、αが０のときに無補正（０パーセント補正）の状態となり、αが１のとき完全補正（１００パーセント補正、すなわち、投影画像の色が基準投影面に投影した場合とほぼ同じ色になるように補正した状態）がかかる。実験より、αｍｉｎは０．３〜０．８の範囲の値が好適である。
【００８３】
そして、式（４）のパラメータα１は、
【００８４】
【数５】

とする。ここで、Ｙ１の値は０〜２００［ｃｄ／ｍ^２］の範囲が好適であり、Ｙ２の値は２０〜５００［ｃｄ／ｍ^２］の範囲が好適であることを実験により確かめた。
【００８５】
図１０（ａ）に、横軸をスクリーン上での照明の明るさＹ、縦軸をパラメータα１とした場合のグラフを示す。図１０（ａ）に示すように、スクリーン上での照明の明るさＹが明るいほど、α１の値が小さな値となるようにして補正量を小さくする。なお、図１０（ａ）に示すα１のグラフは、単なる一例であり、傾きがゼロまたは負であり、最大値が１、最小値がゼロであれば良い。
【００８６】
式（４）のパラメータα２は、
【００８７】
【数６】

とする。ｘｙ座標系で色度差を求めた場合、Δ１の値は０．００〜０．１５の範囲が好適であり、Δ２の値は０．０５〜０．２０の範囲が好適であることを実験により確かめた。
【００８８】
図１０（ｂ）に、横軸を基準スクリーンとの色度差Δ、縦軸をパラメータα２とした場合のグラフを示す。図１０（ｂ）に示すように、基準スクリーンの色を白とすると使用スクリーンの彩度が大きくなるほど（色度差Δが大きくなるほど）、α２の値が小さくなるようにして補正量を小さくする。なお、図１０（ｂ）に示すα２のグラフは、単なる一例であり、傾きがゼロまたは負であり、最大値が１、最小値がゼロであれば良い。
【００８９】
式（４）のパラメータα３は、
【００９０】
【数７】

とする。Ｒ１の値は１．０〜２．０の範囲が好適であり、Ｒ２の値は１．５〜３．０の範囲が好適であることを実験により確かめた。
【００９１】
図１０（ｃ）に、横軸を投影領域とスクリーンとの面積比Ｒ、縦軸をパラメータα３とした場合のグラフを示す。図１０（ｃ）に示すように、スクリーンが大きくなるほど、α３の値が小さな値となるようにして、補正量を小さくする。すなわち、色変換演算子による補正量を、投影領域と投影面の大きさがほぼ等しいときには前記投影画像の色が基準投影面に投影した場合とほぼ同じ色になるように補正した状態とし、投影面の大きさに対して投影領域の大きさが小さくなるにつれて無補正の状態へと徐々に近づける
なお、図１０（ｃ）に示すα３のグラフは、単なる一例であり、傾きがゼロまたは負であり、最大値が１、最小値がゼロであれば良い。
【００９２】
上記の説明では、Ｓ２４においてスクリーン上での照明の明るさの測定が行われてＹが求められ、Ｓ２６においてスクリーンの色が測定されてΔが求められ、Ｓ２８において投影領域とスクリーンとの面積比Ｒが求められた場合について説明した。しかし、Ｓ２４、Ｓ２６およびＳ２８は何れか一つを行えば本発明による周囲環境の変化に応じた色補正を行うことができる。従って、Ｓ２４における処理を行わずＹを算出しなかった場合にはα１＝０１とし、Ｓ２６における処理を行わずΔを算出しなかった場合にはα２＝０１とし、Ｓ２８における処理を行わずＲを算出しなかった場合にはα３＝０１とする。
【００９３】
Ｓ３０における処理の後、Ｓ３２における処理に移行する。
【００９４】
２−２−７） 変換行列の合成処理（Ｓ３２）
変換行列合成部１００ａは、基準環境データ保存部１００ｂおよび使用環境データ保存部１００ｃにそれぞれ保存した変換行列Ｍ_ｄ０およびＭ_ｄを読み出し、式（４）で求めたパラメータαを重み付け係数として、
Ｍ＝Ｍ_ｄ ^−１［αＭ_ｄ０＋（１−α）Ｍ_ｄ］ …（５）
によって変換行列Ｍ_ｄ０およびＭ_ｄを合成して最終的な変換行列Ｍ（色変換演算子）を求める（Ｓ３２）。
【００９５】
Ｓ３２における処理の後、Ｓ３４における処理に移行する。
【００９６】
２−２−８） 映像信号に対する環境補正処理（Ｓ３４）
映像信号変換部１１０は、式（５）で求めた変換行列Ｍを用いて、入力される映像信号Ｒ_ｉｎ，Ｇ_ｉｎ，Ｂ_ｉｎに対して環境補正処理を施し、補正後の映像信号Ｒ_ｏｕｔ，Ｇ_ｏｕｔ，Ｂ_ｏｕｔを求める。
【００９７】
図１１に、変換行列Ｍを用いての映像信号に対する環境補正処理を説明するためのフローチャートを示す。
【００９８】
まず、入力される映像信号Ｒ_ｉｎ，Ｇ_ｉｎ，Ｂ_ｉｎは、
ｒ_ｉｎ＝（Ｒ_ｉｎ／２５５）^γ
ｇ_ｉｎ＝（Ｇ_ｉｎ／２５５）^γ
ｂ_ｉｎ＝（Ｂ_ｉｎ／２５５）^γ
によってｒ_ｉｎ，ｇ_ｉｎ，ｂ_ｉｎに変換される（Ｓ９４）。
【００９９】
次に、ｒ_ｉｎ，ｇ_ｉｎ，ｂ_ｉｎは、式（５）で求めた変換行列Ｍを用いて、
【０１００】
【数８】

によって、ｒ_ｏｕｔ，ｇ_ｏｕｔ，ｂ_ｏｕｔに変換される（Ｓ９６）。
【０１０１】
但し、ｒ_ｏｕｔ＜０のときにはｒ_ｏｕｔ＝０とし、ｒ_ｏｕｔ＞１のときにはｒ_ｏｕｔ＝１とする。ｇ_ｏｕｔおよびｂ_ｏｕｔについても同様である。
【０１０２】
そして、ｒ_ｏｕｔ，ｇ_ｏｕｔ，ｂ_ｏｕｔは、
Ｒ_ｏｕｔ＝２５５（ｒ_ｏｕｔ）^{１／ γ}
Ｇ_ｏｕｔ＝２５５（ｇ_ｏｕｔ）^{１／ γ}
Ｂ_ｏｕｔ＝２５５（ｂ_ｏｕｔ）^{１／ γ}
によってＲ_ｏｕｔ，Ｇ_ｏｕｔ，Ｂ_ｏｕｔに変換される（Ｓ９８）。
【０１０３】
上記Ｓ９４〜Ｓ９８は映像信号の各画素について繰り返される。映像信号の全ての画素についてＳ９４〜Ｓ９８の処理が終了すると、本発明に係る色変換演算子生成処理の本処理が終了する。
【０１０４】
当該実施形態によれば、スクリーン上での照明の明るさＹ、スクリーンの色（基準スクリーンとの色度差）Δおよび投影領域とスクリーンとの面積比Ｒに基づいて算出された可変パラメータαを重み付け係数として用いて、変換行列Ｍ_ｄ０およびＭ_ｄを合成して最終的な変換行列Ｍ（色変換演算子）を求めている。このため、周囲環境の変化に応じて、過補正であると人間が感じる補正量が変化したとしても、可変パラメータαを用いて適切な色再現が可能な色変換演算子Ｍを生成し、当該色変換演算子Ｍによって適切な環境補正処理を行うことができる。
【０１０５】
第２実施形態
図１２に、本発明の第２実施形態に係るプロジェクタ２０およびアダプタ３００の機能ブロック図を示す。第１実施形態と同一の構成要素に関しては、第２実施形態においても同一の参照番号を付す。
【０１０６】
第１実施形態においてはプロジェクタ２０が色変換演算子生成部１００を備えているが、図１２に示すように、色変換演算子生成部１００を、アダプタ３００としてプロジェクタとは別個に構成してもよい。図１２のように構成しても、第１実施形態と同様の作用効果を奏する。
【図面の簡単な説明】
【図１】本発明に係る画像表示装置の一実施形態にかかるプロジェクタ２０を用いたシステムの概略説明図である。
【図２】本発明の第１実施形態にかかるプロジェクタ２０の機能ブロック図である。
【図３】本発明に係る色変換演算子生成処理の事前処理を説明するためのフローチャートである。
【図４】本発明に係る色変換演算子を用いての環境補正処理の本処理を説明するためのフローチャートである。
【図５】図３のＳ１２に示す基準環境下での色測定および変換行列の生成・保存処理について説明するためのフローチャートである。
【図６】図３のＳ１０に示す投影領域の特定処理について説明するためのフローチャートである。
【図７】図４のＳ２４におけるスクリーン上での照明の明るさ測定処理を説明するためのフローチャートである。
【図８】図４のＳ２６におけるスクリーン色の測定処理を説明するためのフローチャートである。
【図９】図４のＳ２８における投影領域とスクリーンとの面積比の測定処理を説明するためのフローチャートである。
【図１０】対比パラメータαの算出処理を説明するための図である。
【図１１】変換行列Ｍを用いての映像信号に対する環境補正処理を説明するためのフローチャートである。
【図１２】本発明の第２実施形態に係るプロジェクタ２０およびアダプタ３００の機能ブロック図である。
【符号の説明】
１０ スクリーン（投影面）
１２ 投影領域
１４ センシング領域
２０ プロジェクタ
６０ センサ
１００ 色変換演算子生成部
１００ａ 変換行列合成部
１００ｂ 基準環境データ保存部
１００ｃ 使用環境データ保存部
１１０ 映像信号変換部
１２０ パッチデータ生成部
１３０ パラメータα生成部
１４０ Ｌ／Ｖ（ライトバルブ）駆動部
２００ 測定部
２００ａ 変換行列Ｍ_ｄ０生成部
２００ｂ 変換行列Ｍ_ｄ生成部
２００ｃ スクリーンサイズ演算部
２００ｄ スクリーンの色演算部
２００ｅ 照明の明るさ演算部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to image processing for correcting the appearance of a projected image that changes depending on room lighting, screen color, and the like.
[0002]
[Prior art]
Patent Document 1 discloses an image processing technique for correcting a change in appearance in a projected image of a projector due to a change in a surrounding environment. In the technique described in Patent Document 1, a correction amount of RGB gain is calculated from screen information, and a change in appearance of a projected image is corrected using a 1D-LUT based on the calculation result. At this time, an over-correction is prevented by defining a correction amount adjustment parameter having a certain fixed value and taking an intermediate state between no correction and complete correction.
[0003]
[Patent Document 1]
JP-A-2002-94822
[Problems to be solved by the invention]
However, the cause of overcorrection in the correction for the screen color is a comparison effect between the output image after correction and the screen color near the projected image. For this reason, when the appearance of the color on the surrounding screen changes due to the brightness of the room, the correction amount perceived by humans as overcorrection also changes according to the change. It was difficult.
[0004]
The present invention has been made to solve the above problems, and provides a color conversion operator generation apparatus, method, program, recording medium, projector, and adapter that can perform appropriate color reproduction even when the surrounding environment changes. The task is to
[0005]
[Means for Solving the Problems]
In view of the above problems, a color conversion operator generation device according to the present invention is a device that generates a color conversion operator for correcting a change in the appearance of a projected image on a projection plane due to a change in surrounding environment, Parameter calculating means for calculating a parameter indicating a contrast effect between the projected image and the color of the projected surface on the basis of information on the appearance of the projected image in the projection area on the surface; and a change in the surrounding environment based on the calculated parameter. Generating means for generating a color conversion operator for correcting a change in the appearance of the projected image on the projection plane.
[0006]
According to the conversion operator generation device of the present invention, the change in the appearance of the projected image on the projection plane due to the change in the surrounding environment is corrected by the color conversion operator. First, the parameter calculating means calculates a parameter indicating a contrast effect between the projected image and the color of the projected surface, based on the information on the appearance of the projected image in the projection area on the projection surface. Then, based on the calculated parameters, the color conversion operator generating means generates a color conversion operator for correcting a change in the appearance of the projected image on the projection plane due to a change in the surrounding environment.
[0007]
In the color conversion operator generation device according to the present invention, the correction amount by the color conversion operator is corrected according to the parameter so that the color of the projected image is substantially the same as when projected onto a reference projection plane. The configuration is such that the state is adjusted step by step from a state in which the correction is performed to a state in which no correction is performed.
[0008]
The color conversion operator generation device according to the present invention is configured such that the information is a value corresponding to the brightness of the projection plane.
[0009]
In the color conversion operator generation device according to the present invention, when the value corresponding to the brightness is small, the correction amount by the color conversion operator is set to be substantially the same as the color of the projected image when projected onto the reference projection plane. It is configured such that the state is corrected so as to be closer to the uncorrected state as the value corresponding to the brightness increases.
[0010]
In the color conversion operator generation device according to the present invention, the information is configured to be information relating to the color of the projection plane.
[0011]
In the color conversion operator generation device according to the present invention, the information on the color of the projection plane is a chromaticity difference between the color of the reference projection plane and the color of the used projection plane, and the correction amount by the color conversion operator is When the chromaticity difference is small, the state is corrected so that the color of the projected image becomes substantially the same color as when projected on the reference projection plane, and gradually approaches an uncorrected state as the chromaticity difference increases. Is configured.
[0012]
In the color conversion operator generation device according to the present invention, the information is configured to be information on an area ratio between a projection area and a projection plane.
[0013]
In the color conversion operator generation device according to the present invention, the correction amount by the color conversion operator is substantially the same as when the color of the projection image is projected on the reference projection surface when the size of the projection area and the size of the projection surface are substantially equal. It is configured to be in a state corrected so as to become a color, and gradually approaches an uncorrected state as the size of the projection area becomes smaller than the size of the projection plane.
[0014]
The color conversion operator generating device according to the present invention is configured to further include a measuring unit that measures information on how the projected image looks.
[0015]
Further, the projector is configured to include the color conversion operator generation device according to the present invention.
[0016]
Further, the method for generating a color conversion operator according to the present invention is a method for generating a color conversion operator for correcting a change in the appearance of a projected image on a projection plane due to a change in the surrounding environment. A parameter calculating step of calculating a parameter indicating a contrast effect between the projected image and the color of the projected surface based on information on the appearance of the projected image in the projection area; and a projection based on a change in the surrounding environment based on the calculated parameter. And generating a color conversion operator for correcting a change in the appearance of the projected image on the surface.
[0017]
Further, the program according to the present invention is a program for causing a computer to execute a process of generating a color conversion operator for correcting a change in the appearance of a projected image on a projection plane due to a change in an ambient environment. A parameter calculation process of calculating a parameter indicating a contrast effect between the projected image and the color of the projected surface based on information on how the projected image looks in the projection area on the surface; and a change in the surrounding environment based on the calculated parameter. And a generation process for generating a color conversion operator for correcting a change in the appearance of the projected image on the projection plane.
[0018]
Further, a recording medium according to the present invention is configured to record the above-mentioned program and to be readable by a computer.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0020]
First embodiment
1) System configuration
FIG. 1 is a schematic explanatory diagram of a system using a projector 20 according to an embodiment of the image display device according to the present invention. The image display device of the present invention includes a projector, a CRT, a liquid crystal display, and the like.
[0021]
In this system, a predetermined image is projected from a projector 20 provided substantially in front of a screen (projection surface) 10, and desired information (screen color, illumination brightness, screen size, etc.) is detected by a sensor 60. Is done. As the sensor 60, a multi-pixel area sensor is used.
[0022]
Here, an area on the screen 10 where an image is projected is referred to as a projection area 12, and an area where the information can be detected by the sensor 60 is referred to as a sensing area 14. At this time, as shown in FIG. 1, the screen 10, the projector 20, and the sensor 60 are arranged such that the projection area 12 is within the screen 10 and the sensing area 14 can cover the screen 10 projection area 12. Also, when the width of the projection area 12 is W and the height of the projection area is H, an experiment has shown that the width of the sensing area is preferably 1.2 to 2.0 W and the length of the vertical is 1.2 to 2.0 H. Confirmed by.
[0023]
FIG. 2 shows a functional block diagram of the projector 20 according to the first embodiment of the present invention.
[0024]
The projector 20 according to the first embodiment of the present invention uses a color conversion operator generation unit 100 for generating a color conversion operator, and a color conversion operator generated by the color conversion operator generation unit 100. A video signal conversion unit 110 for performing a desired conversion process on an input video signal, and an L / V (light valve) driving unit 140 for driving a liquid crystal light valve to project and display an image. It is configured with.
[0025]
The color conversion operator generation unit 100 includes a conversion matrix synthesis unit 100a, a reference environment data storage unit 100b, a use environment data storage unit 100c, a patch data generation unit 120, a parameter α generation unit 130, and a measurement unit 200.
[0026]
The measuring unit 200 calculates a transformation matrix M_d0Generator 200a, transformation matrix M_dIt includes a generation unit 200b, a screen size calculation unit 200c, a screen color calculation unit 200d, and a lighting brightness calculation unit 200e. The operation of each unit will be described in detail below with reference to flowcharts.
[0027]
In the projector according to the present invention, the color conversion operator generation unit 100 generates a color conversion operator according to the usage environment. The video signal supplied from the personal computer or the like is converted by the video signal conversion unit 110 using the color conversion operator generated by the color conversion operator generation unit 100. The L / V drive unit 140 drives the liquid crystal light valve based on the converted analog signal to perform projection display of an image.
[0028]
2) Operation of the color conversion operator generation unit 100
Next, the operation of the color conversion operator generation unit 100 according to the present invention will be described with reference to FIGS. The processing by the color conversion operator generation unit 100, such as the color conversion operator generation processing described below, is performed by executing a processing program recorded in a program storage unit (not shown) of the projector 20. The program storage unit constitutes a medium on which the processing program is recorded. Further, the processing program itself is also included in the scope of the present invention.
[0029]
2-1) Preliminary processing (Fig. 3)
FIG. 3 shows a flowchart for explaining the pre-processing (under the reference environment) of the color conversion operator generation processing according to the present invention.
[0030]
In this embodiment, the characteristic data of the projector in the reference environment (dark room, reference screen) is required. Then, the transformation matrix M_d0The measurement is performed in advance in the reference environment by the generation unit 200a, and the conversion matrix M_d0Must be generated and stored in the reference environment data storage unit 100b.
[0031]
In the pre-processing shown in FIG. 3, first, the projection area 12 is specified (S10), the output color of the projector 20 is measured under the reference environment, and the conversion matrix is generated and stored (S12). Move on to this processing.
[0032]
2-1-1) Specifying a projection area (S10)
Next, with reference to the flowchart shown in FIG. 6, the process of specifying the projection area 12 shown in S10 of FIG. 3 will be described.
[0033]
First, white is output from the projector 20 to the screen 10 (S60), and the reflected light on the screen 10 is measured by the sensor 60 (S62). Next, black is output from the projector 20 to the screen 10 (S64), and the reflected light on the screen 10 is measured by the sensor 60 (S66). Then, the difference between the two measurement values in S62 and S66 is obtained, the projection area 12 is specified based on the difference between the measurement values (S68), and the projection area specification processing ends.
[0034]
In the present embodiment, the projector outputs white and black to the screen and specifies the projection area from the difference in the luminance value of the reflected light, but the output light from the projector is not specified as white and black, If there is a difference in color or luminance, the projection area can be specified.
[0035]
2-1-2) Color measurement under reference environment and generation and storage of conversion matrix (S12)
Next, with reference to the flowchart shown in FIG. 5, the color measurement and the generation and storage processing of the conversion matrix under the reference environment shown in S12 of FIG. 3 will be described.
[0036]
First, under the reference environment, black (K) is output from the projector 20 to the screen 10 (S40), and the tristimulus value of the reflected light on the screen 10 is measured by the sensor 60 (S42). Then, the values in the projection area 12 are averaged (S44). X is the averaged value_K0, Y_K0, Z_K0And
[0037]
Next, under the reference environment, any one of white (W), red (R), green (G), and blue (B) is output from the projector 20 to the screen 10 (S46). The tristimulus value of the reflected light at is measured (S48). Then, the values in the projection area 12 are averaged (S50). The averaged values for white (W), red (R), green (G), and blue (B) are
X_W0, Y_W0, Z_W0
X_R0, Y_R0, Z_R0
X_G0, Y_G0, Z_G0
X_B0, Y_B0, Z_B0
And Then, the measured value for black is subtracted from the measured value for each color to normalize (S52). For tristimulus values of R
X_Rd0= (X_R0-X_K0) / (Y_W0-Y_K0)
Y_Rd0= (Y_R0-Y_K0) / (Y_W0-Y_K0)
Z_Rd0= (Z_R0-Z_K0) / (Y_W0-Y_K0)
Becomes W, G and B can be similarly calculated.
[0038]
Then, the processing of S46 to S52 is repeated for the four colors of W, R, G and B. In the present embodiment, the case where four colors are used has been described._d0Can be generated. However, accuracy is higher when four colors are used than when three colors are used.
[0039]
Next, the transformation matrix M_d0The generation unit 200a
[0040]
(Equation 1)

, The transformation matrix M under the reference environment_d0Is generated (S54).
[0041]
here,
[0042]
(Equation 2)

And
x_Rd0= X_Rd0/ (X_Rd0+ Y_Rd0+ Z_Rd0)
y_Rd0= Y_Rd0/ (X_Rd0+ Y_Rd0+ Z_Rd0)
z_Rd0= Z_Rd0/ (X_Rd0+ Y_Rd0+ Z_Rd0)
It is. In addition,
x_Gd0, Y_Gd0, Z_Gd0, X_Bd0, Y_Bd0, Z_Bd0The same applies to
[0043]
Then, the generated transformation matrix M_d0Is stored in the reference environment data storage unit 100b (S56), and the processing shifts to the main processing shown in FIG.
[0044]
2-2) Main processing (FIG. 4)
Next, with reference to FIG. 4, a description will be given of the main processing of the environment correction processing using the color conversion operator according to the present invention.
[0045]
In the present process shown in FIG. 4, similarly to the pre-process, first, the projection area 12 is specified (S20), and the output color of the projector 20 is measured under the use environment, and the conversion matrix is generated and stored (S22). .
[0046]
The process of specifying the projection region in S20 and the process of generating and storing the color matrix and the conversion matrix under the use environment in S22 are performed in S10 described with reference to FIG. 6 and in S12 described with reference to FIG. 5, respectively. The processing is performed in a use environment instead of in a reference environment.
[0047]
2-2-1) Specifying a projection area (S20)
The process of specifying the projection area in S20 is the same as the process in S10 described with reference to FIG. 6, and a description thereof will be omitted.
[0048]
2-2-2) Color measurement and generation / save of conversion matrix under use environment (S22)
Next, as in the case of the pre-processing, the color measurement and the generation and storage processing of the conversion matrix under the use environment shown in S22 of FIG. 4 will be described with reference to the flowchart shown in FIG.
[0049]
First, in the use environment, black (K) is output from the projector 20 to the screen 10 (S40), and the tristimulus value of the reflected light on the screen 10 is measured by the sensor 60 (S42). Then, the values in the projection area 12 are averaged (S44). X is the averaged value_K, Y_K, Z_KAnd Here, the brightness of the illumination in the use environment is the brightness Y when the projector projects black._KIs equivalent to
[0050]
Next, under the use environment, any one of white (W), red (R), green (G), and blue (B) is output from the projector 20 to the screen 10 (S46). The tristimulus value of the reflected light at is measured (S48). Then, the values in the projection area 12 are averaged (S50). The averaged values for white (W), red (R), green (G), and blue (B) are
X_W, Y_W, Z_W
X_R, Y_R, Z_R
X_G, Y_G, Z_G
X_B, Y_B, Z_B
And Then, the measured value for black is subtracted from the measured value for each color to normalize (S52). For tristimulus values of R
X_Rd= (X_R-X_K) / (Y_W-Y_K)
Y_Rd= (Y_R-Y_K) / (Y_W-Y_K)
Z_Rd= (Z_R-Z_K) / (Y_W-Y_K)
Becomes W, G and B can be similarly calculated.
[0051]
Then, the processing of S46 to S52 is repeated for the four colors of W, R, G and B. In the present embodiment, the case where four colors are used has been described._d0Can be generated. However, accuracy is higher when four colors are used than when three colors are used.
[0052]
Next, the transformation matrix M_dThe generation unit 200b
[0053]
(Equation 3)

, The transformation matrix M under the use environment_dIs generated (S54).
[0054]
here,
[0055]
(Equation 4)

And
x_Rd= X_Rd/ (X_Rd+ Y_Rd+ Z_Rd)
y_Rd= Y_Rd/ (X_Rd+ Y_Rd+ Z_Rd)
z_Rd= Z_Rd/ (X_Rd+ Y_Rd+ Z_Rd)
It is. In addition,
x_Gd, Y_Gd, Z_Gd, X_Bd, Y_Bd, Z_BdThe same applies to
[0056]
Then, the generated transformation matrix M_dIs stored in the usage environment data storage unit 100c (S56), and the process proceeds to S24 in FIG.
[0057]
2-2-3) Brightness measurement processing of illumination on the screen (S24)
If the room lighting does not have a certain level of brightness, the color in the vicinity of the projection area cannot be perceived, so that no contrast effect occurs. Thus, the illumination brightness calculation unit 200e measures the illumination brightness on the screen.
[0058]
FIG. 7 shows a flowchart for explaining the brightness measurement processing of the illumination on the screen in S24.
[0059]
First, in a use environment, black (K) is output from the projector 20 to the screen 10 (S70), and the reflected light on the screen 10 is measured by the sensor 60 (S72).
[0060]
Specifically, Y described below is measured. The brightness in the projection area when the black is output from the projector can be regarded as a value corresponding to the brightness of the illumination on the screen if the brightness of the black of the projector is small. This is set to Y and used for calculation of a comparison parameter. Y is Y measured in S44_KSince the value is the same as above, the value may be used as it is.
[0061]
Then, the Y values in the projection area 12 are averaged (S74). To show this concretely by mathematical formula,
Y = Y_K= ｛Σ_{(In projection area)}Y_K(I, j)｝ / N (1)
Becomes Where Y_K(I, j) is the measured luminance at each pixel of the sensor, N is the number of pixels in the projection area,_{(In projection area)}Indicates that the sum of pixels in the projection area is calculated.
[0062]
After the processing in S74, the process proceeds to S26 in FIG.
[0063]
2-2-4) Screen color measurement processing (S26)
The projected image is corrected so as to have the same color as when projected on the reference white screen, so that the more the screen color deviates from white, the greater the contrast effect with the screen. The chromaticity difference between the color when the projector outputs white under the reference environment (dark room, white screen) and the use environment can be regarded as a value corresponding to the screen color difference under both environments.
[0064]
FIG. 8 is a flowchart for explaining the screen color measurement processing (processing by the screen color calculation unit) in S26.
[0065]
First, in the use environment, white (W) is output from the projector 20 to the screen 10 (S80), and the sensor 60 measures the reflected light on the screen 10 (S82). Then, as in S74, the measured values in S82 are averaged in the projection area 12 (S84), and the chromaticity is calculated (S86).
[0066]
Next, the measured white value of the projector under the reference environment described with reference to FIG. 3 is read from the data storage unit (S88), and the chromaticity is calculated (S90).
[0067]
Then, a difference between the chromaticity calculated in S86 and the chromaticity calculated in S90 is calculated (S92). The chromaticity difference (the value corresponding to the screen color difference under both environments) between the color when the projector outputs white under the reference environment (dark room, white screen) and the use environment is Δ, and the comparison parameter is calculated. Used for In the present embodiment, the color space for calculating Δ is the Yxy color system, but any color space such as the L * a * b * color system can be used. Δ when the Yxy color system is used is
Δ = ｛(x_W-X_W0)²+ (Y_W-Y_W0)²｝^1/2  … (2)
It is calculated by
[0068]
here,
x_W0= X_W0/ (X_W0+ Y_W0+ Z_W0)
y_W0= Y_W0/ (X_W0+ Y_W0+ Z_W0)
x_W= X_W/ (X_W+ Y_W+ Z_W)
y_W= Y_W/ (X_W+ Y_W+ Z_W)
It is.
[0069]
X_W0, Y_W0, Z_W0Is the white tristimulus value of the projector under the reference environment, and is the value measured in S12 of FIG. Also, X_W, Y_W, Z_WIs the white tristimulus value of the projector under the use environment, and is the value measured in S22 of FIG.
[0070]
As described above, when the Yxy color system is used to calculate Δ, the amount of calculation is smaller than when the L * a * b * color system is used. However, due to the characteristics of the Yxy color system, there is a drawback that when considered over a wide color gamut, the value of Δ does not always match the chromaticity difference felt by a human. Therefore, when higher accuracy is required, it is preferable to use the L * a * b * color system as described below. Δ when using the L * a * b * color system is
Δ = ｛a *_W ²+ B *_W ²｝^1/2
It is calculated by
here,
a *_W= 500 [(X_W/ X_N)^1/3− (Y_W/ Y_N)^1/3]
b *_W= 200 [(Y_W/ Y_N)^1/3− (Z_W/ Z_N)^1/3]
X_N= X_W0Y_W/ Y_W0
Y_N= Y_W
Z_N= Z_W0Y_W/ Y_W0
It is.
[0071]
After the processing in S92, the process proceeds to S28 in FIG.
[0072]
2-2-5) Measurement processing of area ratio between projection area and screen (S28)
If the size of the screen is not larger than the projection area, there is no contrast effect with the color of the screen. Therefore, the screen size calculation unit 200c detects an area having a color near the projection area and near the projection area, and obtains an area ratio with the projection area. The area ratio is set to R and used for calculating a comparison parameter.
[0073]
FIG. 9 is a flowchart for explaining the measurement processing of the area ratio between the projection area and the screen in S28 of FIG.
[0074]
First, black (K) is projected from the projector 20 to the screen 10 (S100), and the chromaticity x at each pixel of the sensor is projected._K(I, j), y_K(I, j) is measured (S102). here,
x_K(I, j) = X_K(I, j) / ｛X_K(I, j) + Y_K(I, j) + Z_K(I, j)｝
y_K(I, j) = Y_K(I, j) / ｛X_K(I, j) + Y_K(I, j) + Z_K(I, j)｝
It is. Where Y_K(I, j) is the measured luminance at each pixel of the sensor.
[0075]
Then, the values in the projection area are averaged to obtain an average chromaticity x in the projection area._K, Y_KAsk for. To show this concretely by mathematical formula,
x_K= ｛Σ_{(In projection area)}x_K(I, j)｝ / N
y_K= ｛Σ_{(In projection area)}y_K(I, j)｝ / N
Becomes Here, N is the number of pixels in the projection area, and Σ_{(In projection area)}Indicates that the sum of pixels in the projection area is calculated.
[0076]
Next, for each pixel outside the projection area, a chromaticity difference from the average chromaticity within the projection area is obtained, and the number of pixels falling within the threshold is counted (S106 to S112).
[0077]
That is, pixels outside the projection area are sequentially selected (S106), and the chromaticity difference S from the average chromaticity within the projection area is selected._K(I, j) is calculated (S108), and S_KIf (i, j) is within the threshold, the counter N_SIs incremented by 1 (S110). S106 to S110 are repeated for all pixels (S112). Expressing S106 to S112 by a mathematical formula,
S_K(I, j) = 1 (| x_K(I, j) -x_K| ≦ Δx and | y_K(I, j) -y_K| ≤ Δy)
S_K(I, j) = 0 (other than above)
N_S= Σ_{(Outside projection range)}S (i, j)
Becomes Where Σ_{(Inside and outside the projection area)}Indicates that a sum is obtained for pixels inside and outside the projection area. Note that the thresholds Δx and Δy are constants, and 0.005 to 0.05 is appropriate.
[0078]
And the total number of counters N_S= Σ_{(Outside projection range)}The size of the screen is calculated from S (i, j) (S114), and the following equation:
R = (N + N_S) / N ... (3)
Then, the area ratio R between the projection area and the screen is calculated (S116).
[0079]
After the process in S116, the process proceeds to S30 in FIG.
[0080]
2-2-6) Calculation process of comparison parameter α (S30)
The parameter α generation unit 130 generates a parameter indicating the degree of the contrast effect based on the brightness Y of the illumination on the screen, the color of the screen (the chromaticity difference from the reference screen) Δ, and the area ratio R between the projection area and the screen. Calculate α.
[0081]
FIG. 10 is a diagram for explaining the process of calculating the comparison parameter α.
[0082]
The contrast parameter α is
α = αmin + (1−αmin) × α1 × α2 × α3 (4)
Required by When α is 0, no correction (0 percent correction) is applied to the input video signal, and when α is 1, complete correction (100% correction, that is, when the color of the projected image is projected on the reference projection plane) (A state corrected so that the color becomes almost the same as the above). From experiments, αmin is preferably in the range of 0.3 to 0.8.
[0083]
Then, the parameter α1 in equation (4) is
[0084]
(Equation 5)

And Here, the value of Y1 is 0 to 200 [cd / m²Is preferable, and the value of Y2 is 20 to 500 [cd / m].²It was confirmed by experiments that the range of [] was suitable.
[0085]
FIG. 10A shows a graph in which the horizontal axis represents the brightness Y of the illumination on the screen and the vertical axis represents the parameter α1. As shown in FIG. 10A, the correction amount is reduced such that the value of α1 becomes smaller as the brightness Y of the illumination on the screen becomes brighter. Note that the graph of α1 shown in FIG. 10A is merely an example, and it is sufficient that the slope is zero or negative, the maximum value is 1, and the minimum value is zero.
[0086]
The parameter α2 in equation (4) is
[0087]
(Equation 6)

And When the chromaticity difference was obtained in the xy coordinate system, it was experimentally determined that the value of Δ1 is preferably in the range of 0.00 to 0.15, and the value of Δ2 is preferably in the range of 0.05 to 0.20. Confirmed by
[0088]
FIG. 10B shows a graph in which the horizontal axis represents the chromaticity difference Δ from the reference screen, and the vertical axis represents the parameter α2. As shown in FIG. 10B, when the color of the reference screen is white, the correction amount is reduced by decreasing the value of α2 as the saturation of the used screen increases (the chromaticity difference Δ increases). . Note that the graph of α2 shown in FIG. 10B is merely an example, and it is sufficient that the slope is zero or negative, the maximum value is 1, and the minimum value is zero.
[0089]
The parameter α3 in equation (4) is
[0090]
(Equation 7)

And Experiments have confirmed that the value of R1 is preferably in the range of 1.0 to 2.0, and the value of R2 is preferably in the range of 1.5 to 3.0.
[0091]
FIG. 10C shows a graph in which the horizontal axis represents the area ratio R between the projection area and the screen, and the vertical axis represents the parameter α3. As shown in FIG. 10C, as the screen becomes larger, the value of α3 becomes smaller, and the correction amount is reduced. That is, when the amount of correction by the color conversion operator is corrected so that the color of the projected image is substantially the same as the color projected on the reference projection surface when the size of the projection area and the size of the projection surface are substantially equal, As the size of the projection area becomes smaller than the size of the surface, it gradually approaches the uncorrected state
Note that the graph of α3 shown in FIG. 10C is merely an example, and it is sufficient that the slope is zero or negative, the maximum value is 1, and the minimum value is zero.
[0092]
In the above description, the brightness of the illumination on the screen is measured at S24 to determine Y, the color of the screen is measured at S26 to determine Δ, and the area ratio between the projection area and the screen is determined at S28. The case where R is determined has been described. However, if any one of S24, S26, and S28 is performed, the color correction according to the change in the surrounding environment according to the present invention can be performed. Therefore, if Y is not calculated without performing the processing in S24, α1 is set to 01, and if Δ is not calculated without performing the processing in S26, α2 is set to 01, and R is set without performing the processing in S28. If not calculated, α3 = 01.
[0093]
After the processing in S30, the process proceeds to S32.
[0094]
2-2-7) Conversion Matrix Combining Process (S32)
The conversion matrix synthesizing unit 100a converts the conversion matrices M stored in the reference environment data storage unit 100b and the usage environment data storage unit 100c, respectively._d0And M_dIs read out, and the parameter α obtained by the equation (4) is used as a weighting coefficient.
M = M_d ^-1[ΑM_d0+ (1-α) M_d] ... (5)
By the transformation matrix M_d0And M_dAre combined to obtain a final conversion matrix M (color conversion operator) (S32).
[0095]
After the processing in S32, the process proceeds to S34.
[0096]
2-2-8) Environment correction processing for video signal (S34)
The video signal conversion unit 110 uses the conversion matrix M obtained by Expression (5) to input the video signal R_in, G_in, B_inIs subjected to environmental correction processing, and the corrected video signal R_out, G_out, B_outAsk for.
[0097]
FIG. 11 shows a flowchart for explaining the environment correction processing for the video signal using the conversion matrix M.
[0098]
First, the input video signal R_in, G_in, B_inIs
r_in= (R_in/ 255)^γ
g_in= (G_in/ 255)^γ
b_in= (B_in/ 255)^γ
By r_in, G_in, B_in(S94).
[0099]
Then, r_in, G_in, B_inIs calculated using the transformation matrix M obtained by the equation (5).
[0100]
(Equation 8)

Gives r_out, G_out, B_out(S96).
[0101]
Where r_outWhen <0, r_out= 0 and r_outR> 1_out= 1. g_outAnd b_outThe same applies to
[0102]
And r_out, G_out, B_outIs
R_out= 255 (r_out)^{1 / γ}
G_out= 255 (g_out)^{1 / γ}
B_out= 255 (b_out)^{1 / γ}
By R_out, G_out, B_out(S98).
[0103]
S94 to S98 are repeated for each pixel of the video signal. When the processing of S94 to S98 is completed for all the pixels of the video signal, this processing of the color conversion operator generation processing according to the present invention ends.
[0104]
According to the present embodiment, the variable parameter α calculated based on the brightness Y of the illumination on the screen, the color of the screen (the chromaticity difference from the reference screen) Δ, and the area ratio R between the projection area and the screen is calculated. Using the transformation matrix M as a weighting factor_d0And M_dTo obtain a final conversion matrix M (color conversion operator). For this reason, even if the correction amount perceived by humans as being overcorrection changes in accordance with changes in the surrounding environment, a color conversion operator M capable of appropriately reproducing colors using the variable parameter α is generated. An appropriate environment correction process can be performed by the color conversion operator M.
[0105]
Second embodiment
FIG. 12 shows a functional block diagram of a projector 20 and an adapter 300 according to the second embodiment of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals in the second embodiment.
[0106]
In the first embodiment, the projector 20 includes the color conversion operator generation unit 100. However, as illustrated in FIG. 12, the color conversion operator generation unit 100 may be configured separately from the projector as the adapter 300. Good. Even with the configuration shown in FIG. 12, the same operation and effect as those of the first embodiment can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of a system using a projector 20 according to an embodiment of an image display device according to the present invention.
FIG. 2 is a functional block diagram of the projector 20 according to the first embodiment of the present invention.
FIG. 3 is a flowchart illustrating a pre-process of a color conversion operator generation process according to the present invention.
FIG. 4 is a flowchart for explaining a main process of an environment correction process using a color conversion operator according to the present invention.
FIG. 5 is a flowchart for explaining color measurement and conversion matrix generation / storage processing under a reference environment shown in S12 of FIG. 3;
FIG. 6 is a flowchart illustrating a process of specifying a projection area shown in S10 of FIG. 3;
FIG. 7 is a flowchart illustrating a process of measuring the brightness of illumination on a screen in S24 of FIG. 4;
FIG. 8 is a flowchart for explaining a screen color measurement process in S26 of FIG. 4;
FIG. 9 is a flowchart illustrating a process of measuring the area ratio between the projection area and the screen in S28 of FIG. 4;
FIG. 10 is a diagram for explaining a calculation process of a comparison parameter α.
FIG. 11 is a flowchart illustrating an environment correction process for a video signal using a conversion matrix M;
FIG. 12 is a functional block diagram of a projector 20 and an adapter 300 according to a second embodiment of the present invention.
[Explanation of symbols]
10. Screen (projection surface)
12 Projection area
14 Sensing area
20 Projector
60 sensors
100 Color conversion operator generator
100a transformation matrix synthesis unit
100b Reference environment data storage unit
100c Usage environment data storage
110 Video signal converter
120 Patch data generation unit
130 Parameter α generation unit
140 L / V (light valve) drive unit
200 measuring unit
200a Conversion matrix M_d0Generator
200b Conversion matrix M_dGenerator
200c screen size calculator
200d Screen color calculation unit
200e Illumination brightness calculator

Claims (13)

An apparatus for generating a color conversion operator for correcting a change in the appearance of a projected image on a projection plane due to a change in an ambient environment,
Parameter calculation means for calculating a parameter indicating a contrast effect between the projected image and the color of the projected surface, based on information on how the projected image looks in the projection area on the projection surface;
Generating means for generating a color conversion operator for correcting a change in the appearance of the projected image on the projection plane due to a change in the surrounding environment, based on the calculated parameters;
A color conversion operator generation device comprising: The color conversion operator generation device according to claim 1, wherein
The correction amount by the color conversion operator is stepwise changed from a state in which the color of the projected image is corrected to be substantially the same color as when projected on a reference projection surface, to an uncorrected state, according to the parameter. A color conversion operator generation device that adjusts to. The color conversion operator generation device according to claim 1 or 2,
A color conversion operator generation device, wherein the information is a value corresponding to the brightness of a projection plane. The color conversion operator generation device according to claim 3, wherein
When the value corresponding to the brightness is small, the correction amount by the color conversion operator is set to a state where the color of the projected image is corrected to be substantially the same color as when projected on a reference projection surface, and the brightness is adjusted to the brightness. A color conversion operator generation device that gradually approaches an uncorrected state as the corresponding value increases. The color conversion operator generation device according to any one of claims 1 to 4,
A color conversion operator generation device, wherein the information is information on a color of a projection plane. The color conversion operator generation device according to claim 5, wherein
The information on the color of the projection plane is a chromaticity difference between the color of the reference projection plane and the color of the used projection plane, and the amount of correction by the color conversion operator is different when the chromaticity difference is small. A color conversion operator generation device, which is in a state where it is corrected so as to have substantially the same color as when projected on a reference projection plane, and gradually approaches an uncorrected state as the chromaticity difference increases. The color conversion operator generation device according to claim 1, wherein:
A color conversion operator generation device, wherein the information is information on an area ratio between a projection area and a projection surface. The color conversion operator generation device according to claim 7, wherein
The amount of correction by the color conversion operator is corrected when the size of the projection area and the projection plane are substantially equal to each other so that the color of the projected image is substantially the same as the color projected on the reference projection plane. A color conversion operator generation device that gradually approaches an uncorrected state as the size of the projection area becomes smaller with respect to the size of. The color conversion operator generation device according to claim 1, wherein:
A color conversion operator generation device further comprising a measurement unit for measuring information on how the projected image looks. A projector comprising the color conversion operator generation device according to any one of claims 1 to 9. A method for generating a color conversion operator for correcting a change in appearance of a projection image on a projection plane due to a change in an ambient environment,
A parameter calculating step of calculating a parameter indicating a contrast effect between the projected image and the color of the projected surface, based on information on how the projected image looks in a projection area on the projection surface;
Based on the calculated parameters, a generation step of generating a color conversion operator for correcting a change in the appearance of the projected image on the projection plane due to a change in the surrounding environment;
A color conversion operator generation method comprising: A program for causing a computer to execute a process of generating a color conversion operator for correcting a change in the appearance of a projected image on a projection plane due to a change in an ambient environment,
A parameter calculation process for calculating a parameter indicating a contrast effect between the projected image and the color of the projected surface, based on information on how the projected image looks in the projection area on the projection surface;
Based on the calculated parameters, a generation process of generating a color conversion operator for correcting a change in the appearance of the projected image on the projection plane due to a change in the surrounding environment;
A program for causing a computer to execute. A computer-readable recording medium on which the program according to claim 12 is recorded.

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