JP3919069B2 - Eyeglass lens performance display method and apparatus - Google Patents

Description

の式になる。上記式の右辺第１項は、球面波成分、第２項は乱視波成分である。ここでＤ_maxは最大曲率、Ｄ_minは最小曲率で、

である。
【００２１】
また、平均曲率は、
Ｄ_ave＝（１／２）（Ｄ_max＋Ｄ_min）＝ （１／２）（Ｄ_yy＋Ｄ_zz）
であり、乱視成分は、
Ｄ_as＝Ｄ_maxーＤ_min＝２｛（１／４）（Ｄ_yy−Ｄ_zz）²＋Ｄ_yz ²｝^1/2
と定義する。
【００２２】
一方、乱視を持つ目の屈折状態は、同様に点Ｒにおける矯正波面形状で表わすことができる。仮に乱視度数と方向を含めた遠用矯正波面を
ｘ_c＝（１／２）Ｃ_yyｙ²＋Ｃ_yzｙｚ＋（１／２）Ｃ_zzｚ²
で表わすと、目の遠用平均度数は、
Ｃ_ave＝（１／２）（Ｃ_yy＋Ｃ_zz）
乱視成分は、
Ｃ_as＝２｛（１／４）（Ｃ_yy−Ｃ_zz）²＋Ｃ_yz ²｝^1/2
となる。
【００２３】
同様に目の調節パワーの波面を定義できる。調節により乱視の度数や方向が変わることも考えられるが、ここでは調節による乱視変化のないケースについて説明する。目の調節パワーの波面は、
ｘ_A＝（１／２）Ａ（ｙ²＋ｚ²）
と表せる。ここで、Ａは調節パワーである。
【００２４】
さて、物体点Ｐを見る場合の眼鏡レンズ矯正効果波面は、
ｘ＝ｘ_C−ｘ_A−ｘ_D
で表わすことができる。上記各式を代入し整理し、座標回転を行い、球面波成分と乱視波成分とにまとめると、
ｘ＝（１／２）ΔＤ（ｙ^''2＋ｚ^''2）＋（１／４）ΔＤ_as（ｙ^''2−ｚ^''2）
となる。ここで、
ΔＤ＝Ｃ_ave＋Ａ−Ｄ_ave
ΔＤ_as＝２［（１／４）｛（Ｃ_yy−Ｄ_yy）−（Ｃ_zz−Ｄ_zz）｝²
＋（Ｃ_yz−Ｄ_yz）²］^1/2
である。ΔＤは平均度数過不足量、ΔＤ_asは残存乱視成分量と定義する。また、調節パワーＡは０から最大調節パワーＡ_maxの間の、ΔＤの絶対値が最小になる値をとる。ΔＤが正のときは度数不足といい、負のときは度数過剰という。
【００２５】
▲２▼変形指数取得工程
この工程は、眼鏡レンズ上の任意の点を通して空間上の任意の物体点を見るときに感ずる変形の程度を表す変形指数を求める工程である。ここで、物体点の変形の意味は、物体点を中心とする微小円形が、レンズを通して見るとどのような形状に見えるか、ということであるということができる。ほとんどの場合、その形状は楕円と見做すことができるので、楕円パラメータで変形指数を定義することができる。
【００２６】
変形楕円は、物体点主光線の近傍の主光線を追跡することによって得られる。図５は物体点を中心とする微小円形の主光線を追跡する場合の説明図である。図５に示されるように、物体点Ｐを中心とし、半径ｄｒの円周上すべての物体点（ｄｒ，θ）の主光線を追跡すると、レンズ通過後の位置（ｄｒ’，θ’）が得られ、その軌跡、つまり、変形楕円が求められる。ｄｒは空間上の長さではなく、ＯＰからの偏角のタンジェントである。
【００２７】
実際は、円周上の全ての点に対して主光線を追跡するのではなく、物体側偏角に対する像側偏角の偏導関数値∂μ’／∂ｕ，∂μ’／∂ν，∂ν’／∂ｕ，∂ν’／∂ν、又は、逆に、像側偏角似対する物体側偏角の偏導関数値∂μ／∂ｕ’，∂μ／∂ν’，∂ν／∂ｕ’，∂ν／∂ν’を求めれば、変形楕円が得られる。後者を例にし、偏導関数値∂μ／∂ｕ’＝Ａ，∂μ／∂ν’＝Ｂ，∂ν／∂ｕ’＝Ｃ，∂ν／∂ν’＝Ｄと書き換えて説明すると、以下のとおりである。
【００２８】
すなわち、

である。
【００２９】
つまり、
（ｄｒ’／ｄｒ）²＝ｐ／｛１＋ｅｃｏｓ２（θ’−α）｝
である。ここで、

である。
【００３０】
このように、ｐ＞０，０≦ｅ≦１なので、拡大率ｄｒ’／ｄｒが方位角θ’によって変わる関数は楕円関数である（図５参照）。この楕円を変形楕円と呼ぶ。最大、最小拡大率、つまり、変形楕円の長軸と短軸との長さは、それぞれ、ａ＝｛ｐ／（１−ｅ）｝^1/2，ｂ＝｛ｐ／（１＋ｅ）｝^1/2となる。本発明では、スケールファクターの（ａｂ）^1/2と、長短軸比のａ／ｂと、これら両者を組み合わせた量を変形の程度（＝度合）を表す変形指数と定義する。ここで、

である。
【００３１】
変形指数取得工程では、原画像または歪原画像の各画素の代表する物体点に対し、上記方法を用いて変形指数を求める工程である。上記方法では、画像全ての物体点に対して変形指数の計算を行なう必要があるが、スプライン補間法という数学手法を用いれば、一定の誤差範囲内において少ない計算量で変形指数を求めることが可能である。変形指数分布像の作成は図４に示される流れにしたがって行なわれる。∂μ／∂ｕ’，∂μ／∂ν’，∂ν／∂ｕ’，∂ν／∂ν’を求めるには、光線追跡法のほかに、あらかじめ計算しておいた主光線データのスプライン補間式の微分計算で求める方法もある。
【００３２】
平均度数過不足量、残存乱視成分量工程では、原画像または歪み原画像の各画素の代表する物体点に対し、上記方法を用いて平均度数過不足量と残存乱視成分量を求める工程である。上記の方法では、画像上全ての物体点に対して平均度数過不足量、残存乱視成分量、残存乱視成分量の計算を行う必要があるが、スプライン補間法という数学手法を用いれば、一定の誤差範囲内において少ない計算量で、平均度数過不足量、残存乱視成分量、残存乱視成分量を求めることが可能である。平均度数過不足量、残存乱視成分量分布像の作成は図２に示されるながれによって行う。
【００３３】
▲３▼ ＰＳＦ取得工程
この工程は、眼の光学系として調節対応眼球モデルを導入し、原画像作成工程で得られた物体点距離と、歪み原画像作成工程で得られた眼鏡レンズ通過点における度数に合わせて眼球モデルの調節状態を設定し、眼鏡レンズと主光線方向に合わせて回旋した眼球モデルとの合成光学系において、物体点から出射する光線による調節対応眼球モデルの網膜上の輝度分布を表すＰＳＦ（Ｐｏｉｎｔ ｓｐｒｅａｄ ｆｕｎｃｔｉｏｎ： 点広がり関数）を求める工程である。
【００３４】
（ア） 調節対応眼球モデルの導入
網膜上のＰＳＦを求めるためには、眼球光学系の導入が必要である。この場合、眼には物体距離に合わせて調節作用があるので、それも考慮しなければならない。この実施例では、調節作用も考慮した眼球光学系モデルであるＲ．Ｎａｖａｒｒｏらによる調節依存性眼球モデルを用いた。Ｎａｖａｒｒｏのモデルでは近軸値のみならず、球面収差と色収差も眼の実測値に合わせるようになっている。簡単な４面構成で、そのうち３面は軸対称二次曲面の非球面である。水晶体は屈折率分布構造になっておらず、追跡計算が簡単である。曲率半径、厚み、非球面度は調節パワーの対数に比例して変化する。図８にＮａｖａｒｒｏらによる眼球モデルの無調節時の光学パラメータを示した。また、図９に調節依存するパラメータの依存式を示した。非球面は、ｙ²＋ｚ²＋（１＋Ｑ）ｘ²−２Ｒｘ＝０で表される。Ｑは非球面度である。
【００３５】
（イ） ＰＳＦの計算
Ａ） ＰＳＦの意味
ＰＳＦは、図１０に示したように、実物体の一点から放射された光線が結像面に集光される点（スポット）の集合状態を表す関数であり、単位面積あたりのスポット数で表わすことができる。完全な光学系であればＰＳＦは結像点にすべてのスポットが集まり、その分布は垂直な直線となるが、通常は広がったガウス分布に類似した形状となる。
【００３６】
Ｂ） ＰＳＦの取得方法
図１１は物体点Ｐを、レンズ上のＱ点を通して見た場合のＰＳＦを求めるための光学系において追跡光線と入射瞳の関係を示す図である。物体点Ｐからの光線は、レンズ表面Ｑ点で屈折され、射出方向は変化し、回旋点Ｏに到達する。眼には物体点Ｐが射出光線方向ＱＯの延長線上にあるように見える。このように、Ｐを見るときはまず眼球の光軸をＱＯ方向に回旋し、そしてＰの距離およびＱ点の屈折力に合わせて調節度を決め、調節を行う。この時点で光学系が固まり、ＰＳＦを求めることができる。
【００３７】
上述のように、ＰＳＦは物体点から放射され、入射瞳を均等に分割した多数の領域の中心を通過した光線の、結像面上のスポットの密度である。入射瞳の位置は、厳密にいうと瞳孔の物体側共役点である。しかし、瞳孔位置は回旋によって変化し、調節状態によってもその共役点の位置が異なる。一方、回旋中心の位置は固定であるうえ、瞳孔の共役点との距離が物体距離に比べて微小である。したがって、裸眼の場合入射瞳の位置は回旋中心と考えても差し支えない。眼鏡を装用したとき、光学系全体の入射瞳は回旋中心点の眼鏡レンズに対する共役点だが、累進レンズの場合通過点によってパワーが異なり、その位置が微妙に変化する。その変化量も物体距離に比較して微小であるので、入射瞳の位置はＰＱの延長線上のＯ’点にあり、ＰＯ＝ＰＯ’と仮定することができる。
【００３８】
正確なＰＳＦを求めるには、入射瞳を均一分布の多数の小領域に分割することが重要である。図１２のように、格子分割と螺線分割の二種類の分割法がある。格子分割は良い均等性が得られるが、四隅の無駄な部分があるため、予定光線の７０％程度しか追跡できない。一方螺線分割では均等性を保ちながら無駄な光線追跡が生じない。この実施例では螺線分割法を採用した。
【００３９】
このように、ＰＳＦは物体点から発射して入射瞳の均等分割点を通過する多数の光線を追跡し、網膜面上のスポットの密度を計算することで得られる。上記ＰＳＦ取得方法は、すべての物体点と入射瞳分割点の組み合わせに対して光線追跡計算をする必要があるが、スプライン補間法という数学的手法を用いれば、一定の誤差範囲内において少ない計算量で網膜面上のスポット位置を求め、さらに網膜面上のスポットの密度であるＰＳＦを取得することが可能である。
【００４０】
以上の方法で求めたＰＳＦは歪み原画像との畳み込み演算により、眼鏡レンズをかけて外界を見るときのボケを正確に反映することができる。しかし、このままの形のＰＳＦでは、計算時間が長く、レンズの結像性能の定量分析などに用いるには不便である。ＰＳＦをある種の関数に近似させ、その関数のパラメータを用いれば、定量分析が容易に行える。以下ＰＳＦを二次元正規分布関数に近似させる方法を述べる。
【００４１】
【数１】

ここで、μ，νはそれぞれ網膜上縦、横方向の偏移量、σ_μ，σ_ν，ρは正規分布のパラメータである。これらのパラメータは下記の性質を持っている。
−１＜ρ＜１
σμ＞０
σν＞０
上式の指数部が−１／２となる点の軌跡は、
（μ²／σ_μ ²）＋（ν²／σ_ν ²）−（２ρμν／σ_μσ_ν）＝１−ρ²
で表わされる楕円で、ＰＳＦの広がる範囲を表わすことができる、楕円の長短軸の長さ比や、長軸の方向などは、非点収差の大きさと方向に密接に関係する。
【００４２】
二次元正規分布関数のパラメータσ_μ，σ_ν，ρを、光線データから求める方法を考えると、（μ，ν）平面に散布する多数の光線の交点（各交点が入射瞳上の各分割点に対応）の統計値を求めて、σ_μ，σ_ν，ρにあてる方法を自然に浮かぶ。つまり、
【数２】

である。ここで、Ｎは光線数で、（μ_i，ν_i）は交点座標である。
σ_{μ 0}、σ_{ν 0}、ρをそのまま近似正規分布のパラメータとすると、分布状況によっては、実際のＰＳＦと乖離してしまうことも考えられる。その場合は適切な比例常数ｋを定め、σ_μ＝ｋσ_{ν 0}、σ_ν＝σ_{ν 0}でパラメータを調整する必要がある。
このように、網膜上光線スポットの統計量を用いて、ＰＳＦの近似関数となる二次元正規分布関数のパラメータを取得することができる。上記の方法でＰＳＦを二次元正規分布関数に近似させてそのパラメータを求める方法を採用する場合、すべての物体点に対して光線追跡及び統計計算を行う必要があるが、スプライン補間法という数学的手法を用いれば、一定の誤差範囲内において少ない計算量で二次元正規分布関数のパラメータを取得することが可能である。
【００４３】
（ウ） ＰＳＦよりボケ指数の算出
ボケ指数は、ボケを表わすＰＳＦ（Ｐｏｉｎｔ Ｓｐｒｅａｄ Ｆｕｎｃｔｉｏｎ）の広がる範囲の大きさを表わすもので、小さいほど画質がよく、はっきり見えるという意味である。２次元正規分布関数で近似されるＰＳＦは、その広がり範囲が楕円で表わすことができるので、楕円の大きさを表わす数値をボケ指数として定義できる。また、ボケ指数の定義は、無謬性と定常性が要求される。無謬性というのは、矛盾が起こらないことである。たとえば、楕円の面積をボケ指数と定義する場合、楕円が線分に退化した場合、ボケ指数がゼロとなる。したがってこの場合では、いくら非点収差が大きくても画質がいいことになるという矛盾が起こり、楕円の面積をボケ指数として定義することは適切ではない。定常性とは、楕円の大きさと形が変わらなければ、楕円が回転してもボケ指数が変わらないことである。この実施例では、無謬性と定常性をもつ外接矩形の対角線長の半分をボケ指数として定義する。つまり、Ｐ＝（σ_μ ²＋σ_ν ²）^1/2である。ボケ指数分布像作成は図３に示すながれによって行う。
【００４４】
（５）画像化工程
この工程は、性能指数取得工程で求められた各画素の代表する物体点に対する結像性能指数を画像の濃淡値、またはＲＧＢ輝度値に変換し、原画像、または歪み原画像上の位置に表示した場合の像を作成し、フレーム位置取得工程で作成したレンズフレームマーク画像とを合成して性能指数分布画像を作成する工程である。
【００４５】
図１３は実施例１の原画像を示す図である。卓上に印刷物が置かれ、約８０ｃｍ前方液晶ディスプレイが置かれている。さらに前方２．５ｍには壁がある。この視野を右目遠用０．００Ｄ加入２．５０Ｄの眼鏡用累進レンズ（ＨＯＹＡＬＵＸ ＳＵＭＭＩＴ；ホーヤ株式会社の商品名）を通して見た場合のボケ指数分布像の静止画像が図１４である。視野は左右１０２．５°、上下８６．２°である。眼鏡フレームは天地サイズ４０ｍｍ、幅５０ｍｍのものであり。フレーム上データムラインおよび遠用度数、近用度数測定リングが表示されている。黒側がボケが少ないことを意味し、白側がボケが大きいことを意味する。
【００４６】
図１４の例において、ボケ指数から画像濃淡値への変換は、ボケ指数をＰ（単位ｍｍ）とした場合、画像濃淡値Ｎは、Ｎ＝３．７６７×１０³Ｐで計算された整数で、２５６を超えた場合は２５５の値を付与する。また、表示方法としては、ボケ指数を濃淡値で表すかわりにＲＧＢ三原色輝度値で表すこともできる。ＲＧＢ三原色輝度値で表す場合においては、上記画像濃淡値Ｎから以下の式によってＲＧＢ三原色輝度値に変換することができる。
【数３】

【００４７】
上述のボケ指数分布像は眼鏡レンズの結像性能を如実に再現されていることがわかる。この実施例によれば、眼鏡レンズ通して見たときのレンズの結像性能をレンズ使用状態で見る画像に合わせて表示する事ができ、使用状態のレンズ性能評価が可能になる。
【００４８】
（実施例２）
この実施例は、実施例１における性能指数分布画像の静止画像を、眼の位置と視線方向を変えながら時系列に多数作成し、動画像を得る例である。したがって、この実施例は、原画像を作成する際に、眼の位置、視線方向、仮想物体の移動や変形を時系列にどのように変えるかのストーリーを作成する工程と、時系列に得られた１枚１枚の静止画像を編集して動画像にする工程とを付加する外は基本的に実施例１と同じであるので、図１５に全体の流れを示す図を掲げてその詳細説明は省略する。なお、ストーリーには、レンズ通過点のストーリーも必要であることは勿論である。また、ストーリー作成の方法としては、全ての時刻での眼の位置、視線方向及びレンズ通過点を定めるのではなく、スプライン補間法をとれば、滑らかな視線移動が実現される。
【００４９】
上述の実施例２によれば、累進レンズを通して外界を見るとき性能の、眼の位置を変えたり、視線を移動したり、視線のレンズ上通過位置を変えたりした場合の変化を再現する動画像が得られる。したがって、眼球レンズの結像性能を実際の使用状況に極めて近い形で評価することが可能になる。さらに、この動画像の表示画面にレンズフレームマークを表示するようにすれば、視線のレンズ上での移動を確認しながらの評価が可能になる。
【００５０】
次に上述の実施例で示した方法を実施するための装置について簡単に説明する。図１６は実施例の方法を実施するための装置の概略構成を示すブロック図である。図１６に示したように、この装置は、プロセッサ６１、読取専用メモり（ＲＯＭ）６２、メインメモリ６３、グラフィック制御回路６４、表示装置６５、マウス６６、キーボード６７、ハードディスク装置（ＨＤＤ）６８、外部記憶装置（ＦＤＤ）６９、プリンタ７０、磁気テープ装置７１等から構成されている。これらの要素は、データバス７２によって結合されている。
【００５１】
プロセッサ６１は、装置全体を統括的に制御する。読取専用メモリ６２には立ち上げ時に必要なプログラムが格納される。メインメモリ６３には性能指数分布画像作成、表示を行うためのプログラムが格納される。グラフィック制御回路６４はビデオメモリを含み、得られた画像データを表示信号に変換して表示装置６５に表示する。マウス６６は表示装置上の各種のアイコン、メニュー等を選択するポインティングデバイスである。ハードディスク装置６８はシステムプログラム、性能指数分布画像作成、表示プログラム等が格納され、電源投入後にメインメモリ６３にローディングされる。また、性能指数分布画像等のデータを一時的に格納する。
【００５２】
外部記憶装置６９は原画像データ等の必要なデータを、外部記憶メディア６９ａを通じて入力したり、必要に応じて外部記憶メディア６９ａにセービングしたりする。プリンタ装置７０は性能指数分布画像等をプリントアウトするのに用いられる。磁気テープ装置７１は必要に応じてプログラムやデータを磁気テープにセービングするのに使用する。なお、以上のべた基本構成を有する装置としては、高性能のパーソナルコンピュータや一般の汎用コンピュータを用いて構成することができる。
【００５３】
【発明の効果】
以上詳述したように、本発明にかかる眼鏡レンズの性能表示方法および装置は、眼鏡レンズを通して外界を観察したときの視野内のすべての物体点に対する眼鏡レンズの性能を表わす性能指数を定義して求め、この性能指数の大小を視覚的に把握可能な表示形態で表示することを特徴とするもので、これにより、眼鏡レンズを装用した場合の性能を実際の使用状況に極めて近い形で視覚的に評価することを可能にしている。
【図面の簡単な説明】
【図１】 性能指数分布画像作成の流れを示す図である。
【図２】 平均度数過不足、非点収差分布像作成の流れを示す図である。
【図３】 ボケ指数分布像作成の流れを示す図である。
【図４】 変形指数分布像作成の流れを示す図である。
【図５】 物体点を中心とする微小円形の主光線を追跡する場合の説明図である。
【図６】 裸眼視野の座標系を示す図である。
【図７】 眼鏡レンズを通して見る視野の座標系を示す図である。
【図８】 Ｎａｖａｒｒｏ模型眼の光学パラメータ（非調節状態）の説明図である。
【図９】 Ｎａｖａｒｒｏ模型眼の光学パラメータの調節パワー依存式を示す図である。
【図１０】 ＰＳＦの説明図である。
【図１１】 物体点を見るときの眼鏡光学系を示す図である。
【図１２】 入射瞳分割法の説明図である。
【図１３】 実施例１の原画像を示す図である。
【図１４】 実施例１のボケ指数分布像を示す図である。
【図１５】 性能指数分布画像の動画像作成の流れを示す図である。
【図１６】 本発明にかかる眼鏡レンズ性能表示方法を実施するための装置の構成を示すブロック図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spectacle lens performance display method and apparatus for displaying spectacle lens performance in a form that can be directly evaluated.
[0002]
[Prior art]
As a spectacle lens performance display method, a method of obtaining an average power and astigmatism on the lens surface and expressing the distribution with contour lines on the lens surface is known.
[0003]
[Problems to be solved by the invention]
However, the average power of the lens surface and the astigmatism of the lens surface usually represent only the curved surface performance of the lens surface, and cannot directly represent the performance when observing the outside world through the lens. As a method that takes into account the performance when observing the outside through a lens with the eyesight of a spectacle wearer, the present inventors have developed a simulation method for an eye optical system that simulates the appearance when observing the outside through a spectacle lens. is suggesting. This method is not an optical image projected on the retinal surface of the eye as an image perceived by the eye through a spectacle lens, but an image captured by the fovea by rotating the eyeball with respect to all object points in the field of view. This is a method of creating and using a convoluted retinal image defined as a connected image.
[0004]
The rotated retinal image and its moving image can show the distortion and blur that are felt when looking at the outside through a spectacle lens. However, the rotated retinal image is a result of reflecting the lens imaging performance when viewing each object point in the image, and does not directly represent the imaging performance itself. For example, in a portion where the luminance change of the image is small, the rotated retinal image may have the same result even if the PSF is different. In the case of an original image with a small number of pixels, a PSF having a small spread range cannot be completely reflected.
SUMMARY OF THE INVENTION An object of the present invention is to provide a spectacle lens performance display method and apparatus capable of directly expressing the performance when observing the outside world through a spectacle lens.
[0005]
[Means for Solving the Problems]
As means for solving the above-mentioned problem, the first means is:
Defining a figure of merit that represents the performance of the spectacle lens for all object points in the field of view when the outside world is observed through the spectacle lens, and displaying the magnitude of this figure of merit in a display format that can be visually grasped. This is a characteristic spectacle lens performance display method.
The second means is
By defining a figure of merit that represents the performance of the spectacle lens for all object points in the field of view when the external world is observed through the spectacle lens, the original image of the field of view of the object point or the image of the field of view through the spectacle lens In a spectacle lens performance display method, a grayscale value or RGB three primary color luminance value determined according to the value of the performance index is given to a corresponding pixel of a certain distortion original image, and a performance index distribution image is created and displayed. is there.
The third means is
The step of creating the figure of merit distribution image includes
An original image creation step of creating an image of a specific visual field range entering an eye having a specific rotation center point as an original image, and obtaining a distance from the object point represented by each pixel to the rotation center point;
The distortion of the visual field when viewed through the spectacle lens is obtained using a ray tracing method, and a distortion original image that is an image including the distortion is created, and the original image or each pixel of the distortion original image is represented. A distortion original image creating step for acquiring a spectacle lens passing position of a light beam emitted from an object point;
A spectacle frame position acquisition step for creating a spectacle frame mark image representing the original image of the spectacle frame or the position on the distorted original image using the object point ray spectacle lens passage position data obtained in the distortion original image creation step; ,
In the optical system comprising the spectacle lens and the eyeball model, a performance index acquisition step of acquiring a performance index for the object point represented by each pixel of the original image or the distortion original image;
While creating a figure of merit distribution image by assigning the gray value or RGB three primary color luminance value determined according to the figure of merit obtained in the figure of merit index to the corresponding pixels of the original image or the distorted original image An imaging step of combining with the spectacle frame mark image created in the spectacle frame position acquisition step;
It is the spectacles lens performance display method concerning the 1st or 2nd means characterized by having.
The fourth means is
The step of creating the figure of merit distribution image includes
Create and place a virtual object by computer graphics in a virtual three-dimensional space, place a rotation center point at a specific position in the virtual three-dimensional space, and use the rotation center point as a vertex and a specific central line-of-sight direction central axis An image of a virtual object in the field of view of the specific pyramid range is created as an original image, and an object point distance that is a distance from the object point represented by each pixel of the original image to the rotation center point is obtained. Image creation process;
When the light beam emitted from the object point and passing through the spectacle lens toward the center of rotation is defined as the chief ray, and the exit direction of the chief ray from the rear surface of the spectacle lens is defined as the eyeball rotation direction, the field of view passing through a specific position on the spectacle lens A central principal ray that is a principal ray from an object point in the center and a central eyeball rotation direction that is the direction of eyeball rotation are obtained by a ray tracing method, and a visual field after passing through a spectacle lens that is a field of view having the center eyeball rotation direction as a central axis The position of an object point represented by each pixel of the original image in FIG. 5 is obtained by ray tracing as the eyeball rotation direction with respect to each object point, and is an image of a visual field after passing through a spectacle lens, that is, an image including distortion for each object point. A distortion original image creating step for creating a distortion original image and obtaining a principal ray passing position of a principal ray with respect to each object point;
A spectacle frame position acquisition step for creating a spectacle frame mark image representing the original image of the spectacle frame or the position on the distorted original image using the object point ray spectacle lens passage position data obtained in the distortion original image creation step; ,
An eyeball optical system model corresponding to the adjustment is introduced as the eyeball model, and the object point distance obtained in the original image creation step and the distortion original image with respect to the object point represented by each pixel of the original image or the distortion original image. An eyeball optical system in which the adjustment state of the eyeball optical system model is set in accordance with the spectacle lens power at the principal ray spectacle lens passage position obtained in the creation step, and is rotated in accordance with the eyeball rotation direction with respect to the eyeglass lens and the object point A performance index acquisition step of acquiring a spectacle lens performance index in a synthetic optical system with a model;
A gray scale value or RGB three primary color luminance value determined according to the value of the spectacle lens performance index is given to corresponding pixels of the original image or the distorted original image to create a performance index distribution image, and the frame position acquisition step An imaging process to be combined with the eyeglass frame mark image created in
The eyeglass lens performance display method according to any one of the second to third means.
The fifth means is
An eyeglass lens performance display method according to any one of the first to fourth means, wherein an average power excess / deficiency when viewing each object point is defined as the performance index.
The sixth means is
The eyeglass lens performance display method according to any one of the first to fourth means, wherein a residual astigmatism component when viewing each object point is defined as the performance index.
The seventh means is
A spectacle lens performance indicating method according to any one of the first to fourth means, wherein a blur index representing a degree of blur when viewing each object point is defined as the performance index.
The eighth means is
The eyeglass lens performance display method according to any one of the first to fourth means, wherein a deformation index representing a degree of deformation when viewing each object point is defined as the performance index.
The ninth means is
According to a seventh means, wherein a minute circle centered on each object point is approximated to an ellipse when viewed through a lens, and the size and long / short axis ratio of the ellipse are defined as a deformation index It is a spectacle lens performance display method.
The tenth means is
It is characterized in that a PSF (Point spread function) on the retina when viewing each object point is obtained, an approximate ellipse representing a range in which the PSF extends is obtained, and half of the diagonal length of the circumscribed rectangle of the approximate ellipse is defined as a blur index. This is a spectacle lens performance display method according to the ninth means.
The eleventh means is
A method for displaying the performance of an eyeglass lens when the outside world is observed through the eyeglass lens,
Create and place virtual objects using computer graphics in a virtual three-dimensional space, and create a story of time-series changes in the eye position, central line-of-sight direction, lens system passing point, virtual object deformation, and virtual object movement. According to the story, a spectacle lens performance index distribution image is created using the spectacle lens performance display method according to any one of the first to fourth means at each time point, and the spectacle lens performance index distribution image is edited. The eyeglass lens performance display method is characterized by creating and displaying a moving image of an eyeglass lens performance index distribution image.
The twelfth means is
A device for displaying the performance of a spectacle lens when the outside world is observed through the spectacle lens,
A virtual object created by computer graphics is created and arranged in a virtual three-dimensional space, and this virtual object is an image of a specific viewing angle that enters the eye with a rotation center point at a specific position and a specific central line-of-sight direction. An original image creating means for obtaining an object point distance that is a distance between an object point position represented by each pixel of the original image and a rotation center point of the eye, as an original image;
When the light beam emitted from the object point and passing through the spectacle lens toward the center of rotation is defined as the chief ray, and the exit direction of the chief ray from the rear surface of the spectacle lens is defined as the eyeball rotation direction, the field of view passing through a specific position on the spectacle lens A central principal ray that is a principal ray from an object point in the center and a central eyeball rotation direction that is the direction of eyeball rotation are obtained by a ray tracing method, and a visual field after passing through a spectacle lens that is a field of view having the center eyeball rotation direction as a central axis The position of an object point represented by each pixel of the original image in FIG. 5 is obtained by ray tracing as the eyeball rotation direction with respect to each object point, and is an image of a visual field after passing through a spectacle lens, that is, an image including distortion for each object point. A distortion original image creating means for creating a distortion original image and calculating a principal ray passing position of the principal ray with respect to each object point;
Spectacle frame position acquisition means for generating a spectacle frame mark image representing a position of the spectacle frame on the original image or the distorted original image using the object point ray spectacle lens passing position data obtained in the distortion original image generation step; ,
An eyeball optical system model corresponding to the adjustment is introduced as the eyeball model, and the object point distance obtained in the original image creation step and the distortion original image with respect to the object point represented by each pixel of the original image or the distortion original image. An eyeball optical system in which the adjustment state of the eyeball optical system model is set in accordance with the spectacle lens power at the principal ray spectacle lens passage position obtained in the creation step, and is rotated in accordance with the eyeball rotation direction with respect to the eyeglass lens and the object point A performance index acquisition means for acquiring a spectacle lens performance index in a synthetic optical system with a model;
A gray scale value or RGB three primary color luminance value determined according to the value of the spectacle lens performance index is given to corresponding pixels of the original image or the distorted original image to create a performance index distribution image, and the frame position acquisition step Imaging means for combining with the eyeglass frame mark image created in
It is a spectacles lens performance display apparatus characterized by having.
The thirteenth means is
A device for displaying the performance of a spectacle lens when the outside world is observed through the spectacle lens,
Create and place virtual objects using computer graphics in a virtual three-dimensional space, and create a story of time-series changes in the eye position, central line-of-sight direction, lens system passing point, virtual object deformation, and virtual object movement. Then, according to the story, a spectacle lens performance index distribution image is generated using the spectacle lens performance display device according to the twelfth means at each time point, and the spectacle lens performance index distribution image is edited to edit the spectacle lens performance index distribution image. An eyeglass lens performance display device comprising means for creating and displaying a moving image of an image.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Example 1
FIG. 1 is a diagram showing a flow of creating a spectacle lens performance index distribution image according to Example 1 of the present invention, FIG. 2 is a diagram showing a flow of creating a distribution image of average power excess / deficiency and astigmatism, and FIG. FIG. 4 is a diagram showing a flow of creating an index distribution image, FIG. 4 is a diagram showing a flow of creating a deformation index distribution image, FIG. 5 is an explanatory diagram in the case of tracking a microcircular chief ray centered on an object point, and FIG. FIG. 7 is a diagram showing a coordinate system of a visual field viewed through a spectacle lens, FIG. 8 is a diagram showing optical parameters (non-adjusted state) of a Navarro model eye, and FIG. 9 is an optical diagram of a Navarro model eye. FIG. 10 is an explanatory diagram of a PSF, FIG. 11 is a diagram showing a spectacle eyeball optical system when viewing an object point, and FIG. 12 is a diagram showing a method of dividing an entrance pupil. FIG. 13 shows an original image. FIG. 14 is an example of a blur index distribution diagram based on the distorted original image when observing the field of view shown in the original image of FIG. Hereinafter, the spectacle lens performance display method according to Example 1 of the present invention will be described with reference to these drawings.
[0007]
The spectacle lens performance index display method according to this embodiment is a method of generating and displaying a distribution of spectacle lens performance index as a still image when a three-dimensional object created by computer graphics is viewed through a lens. The distribution of the spectacle lens performance index distribution according to the first embodiment is roughly divided into (1) original image generation process, (2) distortion original image generation process, (3) spectacle frame position acquisition process, and (4) performance index. An acquisition step, and (5) an imaging step.
[0008]
(1) Original image creation process
This process creates and arranges a virtual object by computer graphics in a virtual three-dimensional space, and this virtual object places a rotation center point at a specific position and enters a specific visual field entering a eye having a specific central line-of-sight direction. In this step, a corner image is created as an original image, and an object point distance that is the distance between the object point position represented by each pixel of the original image and the center of rotation of the eye is obtained. This will be described below.
[0009]
(1) Creating a virtual object that is the basis of the original image
First, a virtual three-dimensional object is created and arranged in a virtual three-dimensional space by a known computer graphics technique. For example, an image is created in which desks, chairs, furniture, etc. are arranged in the room, or flower beds, trees, signs, etc. are arranged in the outdoors.
[0010]
  Creation of the original image The virtual object created above is a virtual object in a visual field that is in a specific pyramid range with the rotation center point at a specific position, the rotation center point as a vertex, and a specific center line-of-sight direction as the central axis. Create an image as an original image. That is,FIG.As shown in FIG. 4, a quadrangular pyramid A1A2A3A4 with the rotation center point O as the apex and the central visual line direction OA as the central axis is set as the field of view, and an image in that range is created. The original image coordinates of an arbitrary object point P (x, y, z) in the viewing quadrangular pyramid in the coordinate system with O as the origin and AO as the x axis are U = tan β = y / x, V = tan γ = z / x And Here, β and γ are azimuth angles of P (x, y, z). When each object point in the field of view is projected onto the image in this way, an arbitrary straight line in the space is projected as a straight line on the image, so that the projection has no distortion. An image representing each object point by this projection method is used as an original image.
[0011]
(3) Acquisition of object point distance
In the original image creation step, the distance from the coordinate value of P (x, y, z) to the rotation center point is also obtained.
[0012]
(2) Original distortion image creation process
In this step, an image including distortion due to the spectacle lens is created, and the principal ray passing position of each object point is obtained. Here, a light ray emitted from the object point and passing through the spectacle lens toward the rotation center point is defined as a principal ray. The emission direction of the principal ray from the rear surface of the spectacle lens is the direction in which the eyeball faces in order to see the object point, and is defined as the eyeball rotation direction. In particular, the principal ray from the object point at the center of the visual field is defined as the central principal ray, and the eyeball rotation direction is defined as the center eyeball rotation direction.
[0013]
The original distortion image is an image representing the position of the object point represented by each pixel of the original image in the visual field after passing through the spectacle lens, which is the visual field having the central eyeball rotation direction as the central axis. The central principal ray and the central eyeball rotation direction can be obtained using a ray tracing method so as to pass through a predetermined spectacle lens passage position. The position of each object point in the visual field after passing through the spectacle lens can be represented by the relative position of the eyeball rotation direction from the central eyeball rotation direction. The principal ray for each object point, its spectacle lens passing position, and the eyeball rotation direction can be obtained by the ray tracing method.
[0014]
  That is,FIG.As shown inFIG.When the spectacle lens L is arranged between the eyeball rotation center point O and the visual field center object point A in order to see A, the eyeball needs to be directed to the lens passing point B instead of the OA direction. The ray ABO is the central principal ray, and the BO direction is the central axis of the visual field after passing through the lens. The position of the arbitrary object point in the image of the visual field after passing through the lens is obtained as follows.
[0015]
First, an x′y′z ′ coordinate system is set with O as the origin and the BO direction as the x ′ axis. A principal ray PQO for an arbitrary object point P (x, y, z) is obtained by a ray tracing method. If the lens passing position is Q (x ′, y ′, z ′) and the azimuth angles in the x′y′z ′ coordinate system are β ′ and γ ′, the coordinates in the image after passing through the spectacle lens are as follows: U ′ = tan β ′ = y ′ / x ′, V ′ = tan γ ′ = z ′ / x ′. When each object point in the field of view is projected onto the image of the field of view after passing through the lens in this way, generally, a straight line in the space does not appear as a straight line on the image, so that an image including distortion by the lens is obtained. The image of the visual field after passing through the spectacle lens created in this way is called a distorted original image. Further, in the original distortion image creation step, the principal ray lens passing position of each object point is also obtained.
[0016]
(3) Eyeglass frame position acquisition process
This step uses the information on the spectacle lens passage position obtained in the distortion original image creation step, obtains the position of the edge of the spectacle frame, the hidden mark, etc. on the original image or the distortion original image, and creates the spectacle frame mark image. It is a process. By comparing the spectacle frame mark image with the original image or the distorted original image, it is possible to accurately grasp through which position of the lens the object on the image is viewed.
[0017]
(4) Performance index acquisition process
This process introduces an accommodation-compatible eyeball model as the optical system of the eye, and for each pixel of the original image, from the object point distance obtained in the original image creation process and the object point obtained in the distortion original image creation process Object point imaging performance in a combined optical system consisting of a spectacle lens and an eyeball model rotated in accordance with the principal ray direction by setting the eyeball model adjustment state according to the frequency of the exiting principal ray at the eyeglass lens passing point This is a process for obtaining an index.
[0018]
Examples of the imaging performance index include an average power excess / deficiency amount, a residual astigmatism component amount, a deformation index indicating the degree of deformation, and a blur index indicating the size of the blur. Further, as an example of the blur index, there is a semi-diagonal length of a circumscribed rectangle of an ellipse when a range of PSF (Point spread function) is approximated to an ellipse.
[0019]
(1) Average frequency deficiency, residual astigmatism component quantity acquisition process
FIG.As shown in FIG. 4, the light beam emitted from the arbitrary object point P is refracted at the lens first surface Q point and heads toward the rotation center point O. The lens refraction effect when looking at the point P is that a spherical wave centering on the point P (a plane wave in the case of an infinitely distant object point) propagates along the light beam, and the light beam and the rear vertex spherical surface (centering around the rotation center point O). , The shape of the wavefront when it reaches the intersection R of the spherical surface passing through the rear vertex C of the lens). In a local coordinate system with the point R as the origin and the RO direction as the x axis, the wavefront shape near the point R is generally expressed by the equation
x_D= (1/2) D_yyy²+ D_yzyz + (1/2) D_zzz² It can be expressed as D_yy, D_yzAnd D_zzCan be determined using ray tracing.
[0020]
Furthermore, when the x axis is fixed and the yz axis is rotated by an angle,

It becomes the following formula. The first term on the right side of the above formula is a spherical wave component, and the second term is an astigmatic wave component. Where D_maxIs the maximum curvature, D_minIs the minimum curvature,

It is.
[0021]
The average curvature is
D_ave= (1/2) (D_max+ D_min) = (1/2) (D_yy+ D_zz)
And the astigmatism component is
D_as= D_max-D_min= 2 {(1/4) (D_yy-D_zz)²+ D_yz ²}^1/2
It is defined as
[0022]
On the other hand, the refractive state of an eye having astigmatism can be similarly expressed by a corrected wavefront shape at point R. Temporary correction wavefront including astigmatism power and direction
x_c= (1/2) C_yyy²+ C_yzyz + (1/2) C_zzz²
In the expression, the distance average frequency of eyes is
C_ave= (1/2) (C_yy+ C_zz)
Astigmatism component is
C_as= 2 {(1/4) (C_yy-C_zz)²+ C_yz ²}^1/2
It becomes.
[0023]
Similarly, the wavefront of the eye's accommodation power can be defined. Although the degree and direction of astigmatism may change due to adjustment, a case where there is no astigmatism change due to adjustment will be described here. The wave front of the eye conditioning power is
x_A= (1/2) A (y²+ Z²)
It can be expressed. Here, A is the adjustment power.
[0024]
Now, when the object point P is viewed, the spectacle lens correction effect wavefront is
x = x_C-X_A-X_D
It can be expressed as Substituting and organizing the above equations, rotating the coordinates, and combining the spherical wave component and the astigmatic wave component,
x = (1/2) ΔD (y^{'' 2}+ Z^{'' 2}) + (1/4) ΔD_as(Y^{'' 2}-Z^{'' 2})
It becomes. here,
ΔD = C_ave+ AD_ave
ΔD_as= 2 [(1/4) {(C_yy-D_yy)-(C_zz-D_zz)}²
+ (C_yz-D_yz)²]^1/2
It is. ΔD is the average frequency excess and deficiency, ΔD_asIs defined as the amount of residual astigmatism component. The adjustment power A is from 0 to the maximum adjustment power A._maxThe absolute value of ΔD between the two values becomes a minimum. When ΔD is positive, the frequency is insufficient, and when ΔD is negative, the frequency is excessive.
[0025]
(2) Deformation index acquisition process
This step is a step of obtaining a deformation index representing the degree of deformation felt when viewing an arbitrary object point in space through an arbitrary point on the spectacle lens. Here, the meaning of the deformation of the object point can be said to be what kind of shape the minute circle centered on the object point looks when viewed through the lens. In most cases, the shape can be considered as an ellipse, so the deformation index can be defined by the ellipse parameters.
[0026]
The deformed ellipse is obtained by tracking the chief ray in the vicinity of the object point chief ray. FIG. 5 is an explanatory diagram in the case of tracking a minute circular chief ray centered on an object point. As shown in FIG. 5, when the principal rays of all the object points (dr, θ) on the circumference having the radius dr are centered on the object point P, positions (dr ′, θ ′) after passing through the lens are obtained. The trajectory, that is, the deformed ellipse is obtained. dr is not the length in space but the tangent of the declination from OP.
[0027]
In practice, the principal ray is not traced for all points on the circumference, but the partial derivative values ∂μ '/ ∂u, ∂μ' / ∂ν, ∂ of the image side deviation with respect to the object side deviation ν '/ ∂u, ∂ν' / ∂ν, or conversely, partial derivative values ∂μ / ∂u ', ∂μ / ∂ν', ∂ν / If ∂u ′, ∂ν / ∂ν ′ is obtained, a modified ellipse is obtained. Taking the latter as an example, the partial derivative values ∂μ / ∂u ′ = A, ∂μ / ∂ν ′ = B, ∂ν / ∂u ′ = C, and ∂ν / ∂ν ′ = D will be described. It is as follows.
[0028]
That is,

It is.
[0029]
That means
(Dr '/ dr)²= P / {1 + ecos2 (θ'-α)}
It is. here,

It is.
[0030]
Thus, since p> 0 and 0 ≦ e ≦ 1, the function of changing the enlargement ratio dr ′ / dr depending on the azimuth angle θ ′ is an elliptic function (see FIG. 5). This ellipse is called a deformed ellipse. The maximum and minimum enlargement ratios, that is, the lengths of the major axis and minor axis of the deformed ellipse are a = {p / (1-e)}, respectively.^1/2, B = {p / (1 + e)}^1/2It becomes. In the present invention, the scale factor (ab)^1/2Then, a / b of the major / minor axis ratio and an amount obtained by combining both are defined as a deformation index representing the degree of deformation (= degree). here,

It is.
[0031]
In the deformation index acquisition step, a deformation index is obtained by using the above method for the object point represented by each pixel of the original image or the original distortion image. In the above method, it is necessary to calculate the deformation index for all object points in the image, but if a mathematical method called spline interpolation is used, the deformation index can be obtained with a small amount of calculation within a certain error range. It is. The deformation index distribution image is created according to the flow shown in FIG. To obtain ∂μ / 'u', ∂μ / ∂ν ', ∂ν / ∂u', and ∂ν / ∂ν ', in addition to the ray tracing method, a spline of principal ray data calculated in advance is used. There is also a method of obtaining by an interpolation type differential calculation.
[0032]
The average power excess / deficiency amount and residual astigmatism component amount step is a step of obtaining the average power excess / deficiency amount and residual astigmatism component amount by using the above method for the object point represented by each pixel of the original image or the distorted original image. . In the above method, it is necessary to calculate the average power excess / deficiency amount, the residual astigmatism component amount, and the residual astigmatism component amount for all object points on the image. It is possible to obtain the average power excess / deficiency amount, residual astigmatism component amount, and residual astigmatism component amount with a small amount of calculation within the error range. The average power excess / deficiency amount and the residual astigmatism component amount distribution image are created by the flow shown in FIG.
[0033]
(3) PSF acquisition process
This process introduces an accommodation-compatible eyeball model as the optical system of the eye, and matches the object point distance obtained in the original image creation process and the frequency at the spectacle lens passing point obtained in the distortion original image creation process. In a combined optical system of a spectacle lens and an eyeball model rotated in accordance with the principal ray direction, a PSF (Point spread) representing the luminance distribution on the retina of the accommodation-compatible eyeball model by the light emitted from the object point is set. function: a point spread function).
[0034]
(A) Introduction of accommodation-compatible eyeball model
In order to obtain the PSF on the retina, it is necessary to introduce an eyeball optical system. In this case, since the eye has an adjusting action according to the object distance, it must be taken into consideration. In this embodiment, R.I. An accommodation-dependent eye model by Navarro et al. Was used. In the Navarro model, not only paraxial values but also spherical aberrations and chromatic aberrations are adapted to the actual measured values of the eye. With a simple four-surface configuration, three of them are aspherical surfaces with axially symmetric quadric surfaces. The crystalline lens does not have a refractive index distribution structure, and the tracking calculation is simple. The radius of curvature, thickness, and asphericity change in proportion to the logarithm of the adjustment power. FIG. 8 shows optical parameters when the eyeball model is not adjusted by Navarro et al. Further, FIG. 9 shows the dependency formula of the parameter depending on the adjustment. Aspherical surface is y²+ Z²+ (1 + Q) x²-2Rx = 0. Q is the asphericity.
[0035]
(B) Calculation of PSF
A) Meaning of PSF
As shown in FIG. 10, the PSF is a function that represents an aggregate state of points (spots) where light rays emitted from one point of the real object are collected on the imaging plane, and is represented by the number of spots per unit area. be able to. In the case of a perfect optical system, the PSF has all spots gathered at the image point, and its distribution is a vertical straight line, but usually has a shape similar to a broadened Gaussian distribution.
[0036]
B) Acquisition method of PSF
FIG. 11 is a diagram showing the relationship between the tracking ray and the entrance pupil in the optical system for obtaining the PSF when the object point P is viewed through the Q point on the lens. The light beam from the object point P is refracted at the lens surface Q point, the emission direction changes, and reaches the rotation point O. It appears to the eye that the object point P is on the extended line of the exit light direction QO. Thus, when viewing P, first, the optical axis of the eyeball is rotated in the QO direction, and the degree of adjustment is determined according to the distance of P and the refractive power of the Q point. At this point, the optical system is solidified and PSF can be obtained.
[0037]
As described above, the PSF is the density of spots on the imaging plane of light rays emitted from an object point and passing through the centers of a number of regions obtained by equally dividing the entrance pupil. Strictly speaking, the position of the entrance pupil is the object side conjugate point of the pupil. However, the pupil position changes with rotation, and the position of the conjugate point varies depending on the adjustment state. On the other hand, the position of the center of rotation is fixed, and the distance from the conjugate point of the pupil is very small compared to the object distance. Therefore, in the case of the naked eye, the position of the entrance pupil can be considered as the center of rotation. When wearing spectacles, the entrance pupil of the entire optical system is a conjugate point to the spectacle lens at the center of rotation, but in the case of a progressive lens, the power varies depending on the passing point, and its position changes slightly. Since the amount of change is also small compared to the object distance, the position of the entrance pupil is at the point O ′ on the extension line of PQ, and it can be assumed that PO = PO ′.
[0038]
In order to obtain an accurate PSF, it is important to divide the entrance pupil into a large number of small regions having a uniform distribution. As shown in FIG. 12, there are two types of division methods, lattice division and spiral division. Although good uniformity can be obtained by the grid division, only about 70% of the planned rays can be traced because there are useless portions at the four corners. On the other hand, in the spiral division, unnecessary ray tracing does not occur while maintaining uniformity. In this embodiment, the spiral division method is adopted.
[0039]
In this way, PSF is obtained by tracking a large number of rays that are emitted from an object point and pass through a uniform division point of the entrance pupil, and calculating the density of spots on the retina surface. In the PSF acquisition method, it is necessary to perform ray tracing calculation for all combinations of object points and entrance pupil division points. However, if a mathematical method called spline interpolation is used, a small amount of calculation is required within a certain error range. Thus, it is possible to obtain the spot position on the retinal surface and further obtain the PSF which is the density of the spot on the retinal surface.
[0040]
The PSF obtained by the above method can accurately reflect the blur when the spectacle lens is worn and the outside world is viewed by convolution calculation with the original distortion image. However, in this form of PSF, the calculation time is long and it is inconvenient to use for quantitative analysis of the imaging performance of the lens. If PSF is approximated to a certain function and parameters of the function are used, quantitative analysis can be easily performed. A method for approximating PSF to a two-dimensional normal distribution function will be described below.
[0041]
[Expression 1]

Here, μ and ν are the vertical and horizontal deviations on the retina, and σ, respectively._μ, Σ_ν, Ρ are parameters of a normal distribution. These parameters have the following properties:
−1 <ρ <1
σμ> 0
σν> 0
The locus of the point where the exponent part of the above equation is -1/2 is
(Μ²/ Σ_μ ²) + (Ν²/ Σ_ν ²)-(2ρμν / σ_μσ_ν) = 1−ρ²
The length ratio of the major and minor axes of the ellipse, the direction of the major axis, etc., which can represent the range of PSF expansion, are closely related to the magnitude and direction of astigmatism.
[0042]
Parameter σ of two-dimensional normal distribution function_μ, Σ_νConsidering a method for obtaining, ρ from ray data, statistic values of intersections of a large number of rays scattered on the (μ, ν) plane (each intersection point corresponding to each division point on the entrance pupil) are obtained, and σ_μ, Σ_ν, Ρ is naturally floating. That means
[Expression 2]

It is. Where N is the number of rays and (μ_i, Ν_i) Is the intersection coordinates.
σ_{μ 0}, Σ_{ν 0}If ρ is a parameter of the approximate normal distribution as it is, it may be deviated from the actual PSF depending on the distribution situation. In that case, an appropriate proportional constant k is determined, and σ_μ= Kσ_{ν 0}, Σ_ν= Σ_{ν 0}It is necessary to adjust the parameter.
As described above, the parameters of the two-dimensional normal distribution function, which is an approximate function of PSF, can be acquired using the statistics of the light spot on the retina. When adopting the method of obtaining the parameters by approximating the PSF to the two-dimensional normal distribution function by the above method, it is necessary to perform ray tracing and statistical calculation for all object points. If the method is used, it is possible to acquire the parameters of the two-dimensional normal distribution function with a small amount of calculation within a certain error range.
[0043]
(C) Calculation of blur index from PSF
The blur index represents the size of a wide range of PSF (Point Spread Function) representing blur, and the smaller the blur index, the better the image quality and the clearer it is. A PSF approximated by a two-dimensional normal distribution function can be expressed by an ellipse, so that a numerical value representing the size of the ellipse can be defined as a blur index. In addition, the definition of the blur index requires consistency and stationarity. Innocence means that no contradiction occurs. For example, when the area of an ellipse is defined as a blur index, if the ellipse is degenerated into a line segment, the blur index is zero. Therefore, in this case, a contradiction occurs that the image quality is good no matter how large astigmatism is, and it is not appropriate to define the area of the ellipse as a blur index. The stationarity means that the blur index does not change even if the ellipse rotates unless the size and shape of the ellipse change. In this embodiment, half of the diagonal length of the circumscribed rectangle having invariance and stationarity is defined as the blur index. That is, P = (σ_μ ²+ Σ_ν ²)^1/2It is. The blur index distribution image is created by the flow shown in FIG.
[0044]
(5) Imaging process
In this process, the imaging performance index for the object point represented by each pixel obtained in the performance index acquisition process is converted into a gray value or RGB luminance value of the image and displayed at a position on the original image or the distorted original image. This is a step of creating a performance index distribution image by creating an image and combining the lens frame mark image created in the frame position acquisition step.
[0045]
FIG. 13 is a diagram illustrating an original image according to the first embodiment. The printed material is placed on the table, and the front liquid crystal display is placed about 80 cm. In addition, there is a wall 2.5 meters ahead. FIG. 14 shows a still image of the blur index distribution image when this field of view is viewed through a progressive lens for eyeglasses (HOYALUX SUMMIT; trade name of Hoya Co., Ltd.) with 0.00D addition for right eye distance and 2.50D. The field of view is 102.5 ° left and right, and 86.2 ° up and down. The spectacle frame has a top and bottom size of 40 mm and a width of 50 mm. A datum line on the frame, distance power, and near power measurement ring are displayed. The black side means less blur and the white side means more blur.
[0046]
In the example of FIG. 14, the conversion from the blur index to the image gray value is performed when the blur index is P (unit: mm), and the image gray value N is N = 3.767 × 10.^ThreeIf the integer calculated by P exceeds 256, a value of 255 is assigned. In addition, as a display method, the blur index can be represented by RGB three primary color luminance values instead of gray values. In the case of expressing with RGB three primary color luminance values, the image gray value N can be converted into RGB three primary color luminance values by the following formula.
[Equation 3]

[0047]
It can be seen that the above-described blur index distribution image clearly reproduces the imaging performance of the spectacle lens. According to this embodiment, it is possible to display the imaging performance of the lens when viewed through the spectacle lens in accordance with the image viewed in the lens usage state, and it is possible to evaluate the lens performance in the usage state.
[0048]
(Example 2)
This embodiment is an example in which a large number of still images of the figure of merit distribution image in Embodiment 1 are created in time series while changing the eye position and the line-of-sight direction to obtain a moving image. Therefore, this embodiment can be obtained in a time series, a process of creating a story of how to change the eye position, line-of-sight direction, movement and deformation of a virtual object in time series when creating an original image. The process is basically the same as that of the first embodiment except that the process of editing each still image to make a moving image is the same as in the first embodiment, and FIG. 15 is a detailed diagram illustrating the overall flow. Is omitted. Needless to say, the story also needs a story at the lens passing point. In addition, as a method of creating a story, smooth eye movement can be realized by using a spline interpolation method instead of determining the eye position, the eye direction, and the lens passing point at all times.
[0049]
According to the second embodiment described above, a moving image that reproduces a change in performance when viewing the outside through a progressive lens when the position of the eye is changed, the line of sight is moved, or the position of the line of sight passing through the lens is changed. Is obtained. Therefore, it becomes possible to evaluate the imaging performance of the eyeball lens in a form very close to the actual use situation. Further, if the lens frame mark is displayed on the moving image display screen, the evaluation can be performed while checking the movement of the line of sight on the lens.
[0050]
Next, an apparatus for carrying out the method shown in the above embodiment will be briefly described. FIG. 16 is a block diagram showing a schematic configuration of an apparatus for carrying out the method of the embodiment. As shown in FIG. 16, this apparatus includes a processor 61, a read-only memory (ROM) 62, a main memory 63, a graphic control circuit 64, a display device 65, a mouse 66, a keyboard 67, a hard disk device (HDD) 68, It comprises an external storage device (FDD) 69, a printer 70, a magnetic tape device 71, and the like. These elements are coupled by a data bus 72.
[0051]
The processor 61 controls the entire apparatus as a whole. The read-only memory 62 stores a program necessary for startup. The main memory 63 stores a program for creating and displaying a performance index distribution image. The graphic control circuit 64 includes a video memory, converts the obtained image data into a display signal, and displays it on the display device 65. The mouse 66 is a pointing device for selecting various icons and menus on the display device. The hard disk device 68 stores a system program, performance index distribution image creation, display program, and the like, and is loaded into the main memory 63 after the power is turned on. Data such as a performance index distribution image is temporarily stored.
[0052]
The external storage device 69 inputs necessary data such as original image data through the external storage medium 69a or saves it to the external storage medium 69a as necessary. The printer device 70 is used to print out a performance index distribution image or the like. The magnetic tape device 71 is used to save programs and data to the magnetic tape as necessary. The apparatus having the above basic configuration can be configured using a high-performance personal computer or a general-purpose computer.
[0053]
【The invention's effect】
As described in detail above, the spectacle lens performance display method and apparatus according to the present invention defines a figure of merit that represents the spectacle lens performance for all object points in the field of view when the outside world is observed through the spectacle lens. It is characterized by displaying the magnitude of this figure of merit in a display format that can be visually grasped, so that the performance when wearing spectacle lenses can be visually compared with the actual usage situation. Makes it possible to evaluate.
[Brief description of the drawings]
FIG. 1 is a diagram showing a flow of creating a figure of merit distribution image.
FIG. 2 is a diagram showing a flow of creating an astigmatism distribution image with average power over / under.
FIG. 3 is a diagram illustrating a flow of creating a blur index distribution image.
FIG. 4 is a diagram showing a flow of creating a deformation index distribution image.
FIG. 5 is an explanatory diagram for tracking a minute circular chief ray centered on an object point.
FIG. 6 is a diagram showing a coordinate system of a naked eye visual field.
FIG. 7 is a diagram showing a coordinate system of a visual field viewed through a spectacle lens.
FIG. 8 is an explanatory diagram of optical parameters (non-adjusted state) of a Navarro model eye.
FIG. 9 is a diagram showing an adjustment power dependence equation of optical parameters of a Navarro model eye.
FIG. 10 is an explanatory diagram of PSF.
FIG. 11 is a diagram showing an eyeglass optical system when viewing an object point.
FIG. 12 is an explanatory diagram of an entrance pupil division method.
13 is a diagram showing an original image of Example 1. FIG.
14 is a diagram showing a blur index distribution image of Example 1. FIG.
FIG. 15 is a diagram illustrating a flow of creating a moving image of a figure of merit distribution image.
FIG. 16 is a block diagram showing a configuration of an apparatus for carrying out the spectacle lens performance display method according to the present invention.

Claims (8)

The average power deficit amount, the residual astigmatism component amount, the deformation index representing the degree of deformation, or the magnitude of the blur, which is a performance index representing the performance of the spectacle lens for all object points in the field of view when the outside world is observed through the spectacle lens A spectacle lens performance display method characterized in that any one or more of the blur indexes indicating the accuracy are obtained and the magnitude of the performance index is displayed in a display form that can be visually grasped. The average power deficit amount, the residual astigmatism component amount, the deformation index representing the degree of deformation, or the magnitude of the blur, which is a performance index representing the performance of the spectacle lens for all object points in the field of view when the outside world is observed through the spectacle lens One or more of the blur indexes indicating the degree of the image are obtained, and the corresponding index of the original image of the field of view of the object point or the image of the field of view through the spectacle lens is determined according to the value of the performance index. A spectacle lens performance display method, comprising: assigning gray values or RGB three primary color luminance values determined in advance, and creating and displaying a performance index distribution image. The step of creating the figure of merit distribution image includes
An original image creation step of creating an image of a specific visual field range entering an eye having a specific rotation center point as an original image, and obtaining a distance from the object point represented by each pixel to the rotation center point;
The distortion of the visual field when viewed through the spectacle lens is obtained using a ray tracing method, and a distortion original image that is an image including the distortion is created, and the original image or each pixel of the distortion original image is represented. A distortion original image creation step of acquiring a spectacle lens passing position of a light beam emitted from an object point;
A spectacle frame position acquisition step for creating a spectacle frame mark image representing the original image of the spectacle frame or the position on the distorted original image using the object point ray spectacle lens passage position data obtained in the distortion original image creation step; ,
In the optical system comprising the spectacle lens and the eyeball model, a performance index acquisition step of acquiring a performance index for the object point represented by each pixel of the original image or the distortion original image;
While creating a figure of merit distribution image by assigning the gray value or RGB three primary color luminance value determined according to the figure of merit obtained in the figure of merit index to the corresponding pixels of the original image or the distorted original image An imaging step of combining with the spectacle frame mark image created in the spectacle frame position acquisition step;
The eyeglass lens performance display method according to claim 2, comprising : The step of creating the figure of merit distribution image includes
Create and place a virtual object by computer graphics in a virtual three-dimensional space, place a rotation center point at a specific position in the virtual three-dimensional space, and use the rotation center point as a vertex and a specific central line-of-sight direction central axis An image of a virtual object in the field of view of the specific pyramid range is created as an original image, and an object point distance that is a distance from the object point represented by each pixel of the original image to the rotation center point is obtained. Image creation process;
When the light beam that exits from the object point and passes through the spectacle lens toward the center of rotation is defined as the principal ray, and the exit direction of the principal ray from the rear surface of the spectacle lens is defined as the eyeball rotation direction, A central principal ray that is a principal ray from an object point in the center and a central eyeball rotation direction that is the direction of eyeball rotation are obtained by a ray tracing method, and a visual field after passing through a spectacle lens that is a field of view having the center eyeball rotation direction as a central axis The position of an object point represented by each pixel of the original image in FIG. 5 is obtained by ray tracing as the eyeball rotation direction with respect to each object point, and is an image of a visual field after passing through a spectacle lens, that is, an image including distortion for each object point. A distortion original image creating step for creating a distortion original image and obtaining a principal ray passing position of the principal ray for each object point;
A spectacle frame position acquisition step for creating a spectacle frame mark image representing the original image of the spectacle frame or the position on the distorted original image using the object point ray spectacle lens passage position data obtained in the distortion original image creation step; ,
An eyeball optical system model corresponding to the adjustment is introduced as the eyeball model, and the object point distance obtained in the original image creation step and the distortion original image with respect to the object point represented by each pixel of the original image or the distortion original image. An eyeball optical system in which the adjustment state of the eyeball optical system model is set in accordance with the spectacle lens power at the principal ray spectacle lens passage position obtained in the creation step, and is rotated in accordance with the eyeball rotation direction with respect to the eyeglass lens and the object point A performance index acquisition step of acquiring a spectacle lens performance index in a synthetic optical system with the model;
A gray scale value or RGB three primary color luminance value determined according to the value of the spectacle lens performance index is given to corresponding pixels of the original image or the distorted original image to create a performance index distribution image, and the frame position acquisition step An imaging process to be combined with the eyeglass frame mark image created in
The eyeglass lens performance display method according to claim 2, wherein: A feature is to obtain a PSF (Point spread function) on the retina when viewing each object point, to obtain an approximate ellipse representing the range of PSF expansion, and to define half of the diagonal length of the circumscribed rectangle of the approximate ellipse as a blur index The spectacle lens performance display method according to any one of claims 1 to 4 . A method for displaying the performance of a spectacle lens when the external environment is observed through a spectacle lens, wherein a virtual object is created and arranged by computer graphics in a virtual three-dimensional space, and the eye position, the central line-of-sight direction, and the lens A story of a time-series change of the system passing point, the virtual object deformation amount, and the virtual object movement amount is created, and the spectacle lens performance display method according to any one of claims 2 to 5 is used at each time point according to the story. A spectacle lens performance display method comprising: generating a lens performance index distribution image; and editing and editing each spectacle lens performance index distribution image to generate and display a moving image of the spectacle lens performance index distribution image. A device that displays the performance of a spectacle lens when the external environment is observed through the spectacle lens, and creates and arranges a virtual object by computer graphics in a virtual three-dimensional space, and the virtual object is rotated at a specific position. An image of a specific viewing angle that enters the eye with a center point and a specific center line-of-sight direction is created as an original image, and the distance between the object point position represented by each pixel of the original image and the center of rotation of the eye An original image creation means for obtaining a certain object point distance, and a light beam emitted from the object point and passing through the spectacle lens toward the rotation center point is defined as a principal ray, and an emission direction of the principal ray from the rear surface of the spectacle lens is defined as an eyeball rotation direction. A central principal ray that is a chief ray from an object point at the center of the field of view passing through a specific position on the spectacle lens and a central eye rotation direction that is the eye rotation direction are obtained by a ray tracing method, The position of the object point represented by each pixel of the original image in the field of view after passing through the spectacle lens, which is the field of view with the eyeball rotation direction as the central axis, is obtained by the ray tracing method as the eyeball rotation direction with respect to each object point, and after passing through the eyeglass lens A distortion original image creating means for creating a distortion original image that is an image of a field of view, that is, an image including distortion for each object point, and obtaining a principal ray passing position of the principal ray with respect to each object point, and the distortion original image creation A spectacle frame position acquisition means for creating a spectacle frame mark image representing a position of the spectacle frame on the original image or the distortion original image using the object point ray spectacle lens passage position data obtained in the process, and the eyeball model Introducing an adjustment-compatible eyeball optical system model, the original image creation step for the object point represented by each pixel of the original image or the original distortion image An adjustment state of the eyeball optical system model is set in accordance with the obtained object point distance and the spectacle lens power at the principal ray spectacle lens passage position obtained in the distortion original image creating step, and the spectacle lens and the object point Indicates the average power deficit amount, the residual astigmatism component amount, the deformation index representing the degree of deformation, or the size of the blur, which is the spectacle lens performance index in the combined optical system with the eyeball optical system model rotated according to the eyeball rotation direction a performance index obtaining means for obtaining one or more any of the blur index, the gray value or RGB primary color luminance values determined according to the value of the spectacle lens performance index, the corresponding pixel of said original image or said distorted original image And an imaging means for synthesizing with the eyeglass frame mark image created in the frame position acquisition step. An eyeglass lens performance display device characterized by the above. An apparatus for displaying the performance of an eyeglass lens when the external environment is observed through the eyeglass lens, wherein a virtual object is created and arranged by computer graphics in a virtual three-dimensional space, and the eye position, the central line-of-sight direction, and the lens system passing point, the virtual object deformation amount, the virtual time of the object movement amount to create a story based fluctuations, spectacle lens performance index distribution image by using the spectacle lens performance display device according to claim 7 at each time point according to the story A spectacle lens performance display device comprising: means for editing the spectacle lens performance index distribution image to generate and display a moving image of the spectacle lens performance index distribution image.

Images