JP3560124B2 - Image data interpolation device, image data interpolation method, and medium recording image data interpolation program - Google Patents

Description

【００８１】
となる。
【００８２】
このキュービック法では一方の格子点から他方の格子点へと近づくにつれて徐々に変化していき、その変化具合がいわゆる３次関数的になるという特徴を有している。
【００８３】
非メタコマンド画素の他の一例であるコンピュータグラフィックスのような非自然画に適した補間処理として、ニアリスト法の補間処理を実行可能である。ニアリスト法は図８に示すように、周囲の四つの格子点Ｐｉｊ，Ｐｉ＋１ｊ，Ｐｉｊ＋１，Ｐｉ＋１ｊ＋１と内挿したい点Ｐｕｖとの距離を求め、もっとも近い格子点のデータをそのまま移行させる。これを一般式で表すと、
Ｐｕｖ＝Ｐｉｊ
ここで、ｉ＝［ｕ＋０．５｝、ｊ＝［ｖ＋０．５｝である。なお、［］はガウス記号で整数部分を取ることを示している。
【００８４】
図９は、ニアリスト法で画素数を縦横３倍ずつに補間する状況を示している。補間される画素は最初の四隅の画素のうちもっとも近い画素のデータをそのまま移行させることになる。従って、図１０に示すように白い画素を背景として黒い画素が斜めに配置される元画像は、図１１に示すように黒の画素が縦横に３倍に拡大されつつ斜め方向に配置される関係が保持される。
【００８５】
ニアリスト法においては、画像のエッジがそのまま保持される特徴を有する。それ故に拡大すればシャギーが目立つもののエッジはエッジとして保持される。これに対して他の補間処理では補間される画素を周りの画素のデータを利用してなだらかに変化するようにする。従って、シャギーが目立たなくなる反面、本来の元画像の情報は削られていってしまい、エッジがなくなることになってコンピュータグラフィックスやビジネスグラフなどの非自然画には適さなくなる。
【００８６】
本実施形態においては、上述したニアリスト法とキュービック法とを使用するが、これらの特性の理解のために他の補間手法である共１次内挿法（バイリニア補間：以下、バイリニア法と呼ぶ）について説明する。
【００８７】
バイリニア法は、図１２に示すように、一方の格子点から他方の格子点へと近づくにつれて徐々に変化していく点でキュービック法に近いが、その変化が両側の格子点のデータだけに依存する一次関数的である点で異なる。すなわち、内挿したい点Ｐｕｖを取り囲む四つの格子点Ｐｉｊ，Ｐｉ＋１ｊ，Ｐｉｊ＋１，Ｐｉ＋１ｊ＋１で区画される領域を当該内挿点Ｐｕｖで四つの区画に分割し、その面積比で対角位置のデータに重み付けする。これを式で表すと、
Ｐ＝｛（ｉ＋１）−ｕ｝｛（ｊ＋１）−ｖ｝Ｐｉｊ
＋｛（ｉ＋１）−ｕ｝｛ｖ−ｊ｝Ｐｉｊ＋１
＋｛ｕ−ｉ ｝｛（ｊ＋１）−ｖ｝Ｐｉ＋１ｊ
＋｛ｕ−ｉ ｝｛ｖ−ｊ｝Ｐｉ＋１ｊ＋１
となる。なお、ｉ＝［ｕ］、ｊ＝［ｖ］である。
【００８８】
キュービック法もバイリニア法も一方の格子点から他方の格子点へと近づくにつれて徐々に変化していく点で共通するが、その変化状況が３次関数的であるか１次関数的であるかが異なり、画像としてみたときの差異は大きい。図１３はニアリスト法とキュービック法とバイリニア法における補間結果の相違を理解しやすくするために二次元的に表した図である。同図において、横軸に位置を示し、縦軸に補間関数を示している。ｔ＝０、ｔ＝１、ｔ＝２の位置に格子点が存在し、内挿点はｔ＝０〜１の位置となる。
【００８９】
バイリニア法の場合、隣接する二点間（ｔ＝０〜１）で直線的に変化するだけであるので境界をスムージングすることになり、画面の印象はぼやけてしまう。すなわち、角部のスムージングと異なり、境界がスムージングされると、コンピュータグラフィックスでは、本来あるべき輪郭がなくなってしまうし、写真においてはピントが甘くなってしまう。
【００９０】
一方、キュービック法においては、隣接する二点間（ｔ＝０〜１）においては山形の凸を描いて徐々に近接するのみならず、さらに同二点間の外側（ｔ＝１〜２）において下方に押し下げる効果をもつ。すなわち、あるエッジ部分は段差が生じない程度に大きな高低差を有するように変化され、写真においてはシャープさを増しつつ段差が生じないという好適な影響を及ぼす。ただし、コンピュータグラフィックスでは、エッジのもつ意味合いがアナログ的な変化を意味するものではないので、好適とは言えない。
【００９１】
次に、メタコマンド画素に適用して好適なパターンマッチングの補間処理について説明する。
【００９２】
図１４は色情報仮想描画面に書き込まれた文字画像である。文字も水平方向と垂直方向とに並べられるドットマトリクス状の画素からなり、図１５に示すようにドットを付したところ（●）が画像画素となり、ドットを付していないところ（○）が背景画素である。
【００９３】
パターンマッチングでは、図１５に示すような４×４画素の正方領域である１６画素を一つの領域として予め用意されているパターンデータとマッチングさせ、内側の２×２画素の４画素からなる正方領域について補間画素を生成する。４画素の正方領域であるにも関わらず一回り外側の画素を合わせて参照するのは、周囲の画素の有無によって４画素の正方領域に対する補間結果も変化するからである。図１５においても、４画素としてみたときには一致するものの１６画素として見たときには異なることになる二つのパターンデータを示しており、パターンデータＡでは上下の方向にドットが並びつつ１ドットだけ横に突き出る状況であり、パターンデータＢでは周りにはドットが付されず、４画素のうちの３画素にドットが付されている状況である。パターンデータＡでは突き出るイメージを示すためにも全体として山形のドットとすることが好ましいが、３画素を付すものでは三角形を表すように介するのが好ましい。従って、それぞれに対応する補間画素パターンも異なってくる。
【００９４】
ところで、画像データに応じた描画関数を呼び出して色情報仮想描画面と属性情報仮想描画面に対して画素毎にデータを書き込む際、非メタコマンド画素については書き込まれる画素が特定されているが、メタコマンド画素については描画関数が書き込む画素を演算によって求めることになる。このような性質を有するがために、アプリケーション１２ｄの側でコマンドのパラメータを変えることによって任意の大きさの図形を描画することが可能となる。しかしながら、文字のように、一つの図形に複数のコマンドが対応している場合にはノイズとしての画素が生じてしまうことがある。すなわち、ある倍率ではドットが生じないものの、別の倍率では無意味なドットが生じるのである。特に、複数のコマンドで描画される線分の連結点などで生じやすい。むろん、かかるノイズとしてのドットは無い方が好ましい。
【００９５】
図１６は、本実施形態において採用しているノイズとしてのドットの消去手法を示している。同図（ａ）がオリジナルの画像であるとする。文字の一部を示しているが、枠状の図形の角部であることが分かり、複数の描画コマンドの連結点であると想像できる。むろん、必ずしも連結点である必要はない。
【００９６】
ここで、二点鎖線に囲まれたドットに注目してみると、このドットが特に必要であるようには思われない。なぜなら、他の部分では２ドットの幅の線を示しているようであり、その角部においてことさら突き出るドットを付す必要性が想定しにくいからである。すなわち、本来であれば同図（ｂ）に示すようにこのドットは付されるべきではないと判断することが妥当と思われるのである。むろん、このような判断は領域が小さくなってくると一概には判断できないが、本実施形態のように１６画素をまとめてパターンデータと比較する場合においては、付随的にこのような判断が可能となる。
【００９７】
このような前提のもとで、同図（ｃ）に示すドットがあるパターンデータに対しては、同図（ｄ）に示すようなドットがないことを想定した上での補間画素情報を対応させておく。すると、パターンマッチングを経ることによって、メタコマンド画素を解釈して描画した際に生じたノイズとしての画素は、あたかもそれを変換過程において発見して消去した上で、元のメタコマンド画素に対応するように補間画素を生成したのと同じ結果が得られる。
【００９８】
このようなドットの消去は、メタコマンド全般にも適用できるのは明らかである。従って、１６画素の正方範囲でノイズらしきドットが生じればそのパターンデータにはドットを消去したものとしての補間画素情報を対応づけておけばよい。ただ、文字については小領域に多数の描画コマンドが適用されるという特殊性があり、それが故にノイズとしてのドットが発生しやすいし、ノイズの特定が比較的容易であるといえる。
【００９９】
補間画素パターンは倍率毎に複数セットが用意されており、図１７では縦横方向に１．５倍とする場合の一例を示している。
【０１００】
ところで、パターンマッチングをカラーデータに対応させようとすると、４画素の例であっても極めて多大な数のパターンデータを用意させておかなければならないはずである。すなわち、各画素の取り得る色数の順列に相当する組合せが生じるからである。しかしながら、本実施例においては、パターンの比較はドットの有無で行ない、色の割り振りでカラーデータに対応することとしてその問題を解決した。図１８はその一例を示している。１６画素のパターンデータで比較するのは先程の例と同様として、４画素については各画素の色を補間画素のどの画素に割り当てるか対応づけている。これにより、補間画素の色を決定する前処理も不要となるし、パターンデータの数も少なくなるので、処理量や資源量などは極めて低減する。
【０１０１】
一方、このように１６画素を基準とするパターンマッチングのより具体的な手法について図１９に示している。同図（ａ）は補間処理する元の画素の並びを示しており、１６画素の小領域をずらしながらパターンマッチングを行う。このとき、この小領域を移動させるごとに１６画素の情報を全て更新する必要はない。同図（ａ）では画素として「ＥＦＧＨＩＪＫＬＭＮＯＰＱＲＳＴ」という１６画素を対象としており、同図（ｂ）はこれを処理する上でのＣＰＵなどのデータレジスタ領域を示している。各画素にドットが付されているか否かを１ビットの「１」または「０」で表すことにより、１６ビットのデータ幅があればパターンマッチングは可能である。そして、同図（ａ）に示すように小領域を１画素分だけ移動させる場合には「ＡＢＣＤ」の４画素が新たに小領域に含まれることになるし、「ＱＲＳＴ」の４画素が小領域から外れることになる。すると、同図（ｃ）に示すようにデータレジスタ領域で４ビットシフトし、ＬＳＢ側の４ビットに「ＡＢＣＤ」の４画素に対応する４ビットを導入するだけでよい。
【０１０２】
さらにいうならば、パターンデータの並びについても１６ビットをアドレスとして利用すればマッチングさせる処理というのはアドレスを指定するだけの処理となり、そのまま補間画素情報を取得できるようになる。
【０１０３】
以上のような補間処理が実行可能であることを前提として、ステップＳＴ１０６では画像を種別ごとに読み出して補間処理する。ここでは、大きく分けると非メタコマンド画素とメタコマンド画素とに分類でき、前者のものについては図２０に示すフローでキュービック法やニアリスト法の補間処理を実行するし、後者のものについては図２１に示すフローでパターンマッチングによる補間処理を実行する。図２２は、このようにして種別毎に１ラインを読み出す状況を示しており、属性情報仮想描画面に基づいて色情報仮想描画面の各画素が非メタコマンド画素（「Ｎ」）であるかメタコマンド画素（「Ｃ」「Ｂ」）であるかを判断しながら画素を拾い出していく。なお、このときに予め背景画素として初期化しておいた上で拾い出した画素情報をあてはめていく。
【０１０４】
また、補間処理を実行するには水平方向の画素の並びだけでは不十分であり、垂直方向の画素の情報も必要となってくる。従って、図２３に示すように、実際には４ライン分の画素を読み出してはワークエリアに記憶し、補間処理を実行することになる。この例で４ライン分としているのは、上述したキュービック法やパターンマッチングにおいて４×４画素の正方１６画素を一つの処理単位とするためであり、必要に応じて適宜増減可能である。
【０１０５】
ところで、上述したパターンマッチングによる補間処理ではメタコマンド画素として付されていたドットが消去されることがある。このドットはノイズとして生じていたドットであるから、消去することによってメタコマンド画素は本来の輪郭を取り戻すことになる。しかし、消去されるドットを別の画素で埋め合わす処理は実行していない。従って、種別の異なる画素が隣接しているときにドットが消去されれば、そこには隙間が生じかねない。
【０１０６】
このような場合に予め隣接する画像について領域を拡大させておけば、もう一方の画像にてついて補間処理したときに境界部分が背景画素が生じても下地には隣接画像領域の画素が生成されているので隙間が見えてしまうことがなくなる。
【０１０７】
このため、非メタコマンド画素については、ステップＳＴ２０２にて境界延長処理を実行する。この境界延長処理は、予め、画素の周縁でその境界を広げておく処理である。図２２には非メタコマンド画素が読み出されたときに背景画素に隣接する画素について一画素分だけ外側に複写することにより境界延長処理を実行している。
【０１０８】
図２４は、このようにして境界延長した後で補間処理される場合の対策を示している。同図（ａ）は９画素のうちの３画素（Ａ〜Ｃ）に画素情報が含まれ、残りの６画素は背景画素となっている。そして、同図（ｂ）に示すように、境界に隣接する一画素について境界の外側に複写することにより、境界を延長している。境界延長しない場合には補間処理しても同図（ｃ）に示すようになるだけであるが、境界を延長しておいてから補間処理する場合には同図（ｄ）に示すように本来の境界が外側に広がる。これにより、隣接する画素に対して下地を作っておくことになる。なお、この例では一画素分だけ外側に境界を延長しているが、隣接するメタコマンド画素についてパターンマッチングで消去されるドット数に応じた必要な画素数分だけ境界を延長すればよい。
【０１０９】
ステップＳＴ２０２ではこのような意味で境界延長処理を施しておき、ステップＳＴ２０４にてキュービック法によって補間処理する。すなわち、メタコマンド画素を識別して読み出し、自然画などに対して最適な補間処理を実行することができる。
【０１１０】
ここで、図２０に示すフローでは、一点鎖線で自然画か否かの判断処理と、ニアリスト法による補間処理を示している。上述したように本実施形態においては、ビットマップ画像をメタコマンド画素と判断するものの、さらに画像が自然画であるか否かを判断しても良いことを示した。従って、メタコマンド画素についての種別が分かるようにして仮想領域に書き込んでおくとともに、ステップＳＴ２０８にて自然画であるか否かを判断し、自然画であれば上述したようにステップＳＴ２０４にてキュービック法による補間処理を実行するし、自然画でなければステップＳＴ２１０にてニアリスト法による補間処理を実行するようにしてもよい。
【０１１１】
一方、メタコマンド画素についてはステップＳＴ３０６にてパターンマッチングで補間処理する。これにより、文字についてはノイズとして生じていたドットが消去されて美しい線の文字となるし、ビジネスグラフについては不自然なドットのない滑らかな画像となり、最適な補間処理を実行できる。
【０１１２】
メタコマンド画素については、補間処理の際にドットの欠けが生じることがあるが、その対策は隣接する非メタコマンド画素について境界延長しておくとともに、メタコマンド画素を上書きすることで対処している。すなわち、非メタコマンド画素については、補間処理を終えた後、ステップＳＴ２０６にて先書き込みを行ない、メタコマンド画素については、補間処理を終えた後、ステップＳＴ３０８にて後書き込みを行う。なお、図２０および図２１のフローチャートでは、これらのステップＳＴ２０６とステップＳＴ３０８を一点鎖線で表している。これは実際にはこれらの処理が図４のフローチャートに示すステップＳＴ１０８の補間画像重ね合わせ処理に該当するからである。
【０１１３】
ステップＳＴ２０６の先書き込みの処理とステップＳＴ３０８の後書き込みの処理が意味するところは、非メタコマンド画素とメタコマンド画素とを分離してそれぞれ別個のワークエリアにおいて画素補間した後、それぞれを合体せしめるにあたり、境界延長した非メタコマンド画素を先に書き込み、元のメタコマンド画素に対応した補間処理を実現したメタコマンド画素を後に書き込むということである。この場合、先に書き込んである画素と後に書き込む画素とが重ならない場合は先に書き込んである画素は残るものの、重なる場合は後に書き込む画素が残ることになる。従って、両者が隣接する境界で後に書き込む側の境界形状が変化したとしても下地が表れることはない。むろん、背景画素については上書きする必要が無く、上書きされるのは背景画素以外の画素であることは当然である。
【０１１４】
この先後の順序は重ね合わせ処理の際の優先処理の一態様である。かかる優先処理の書き込み制御は実際のプログラムにおいてはテクニックによってどのようにでもなる。このため、実質的に優先処理が維持されればよく、先後に限らず他の手法で同様の処理を実現するようにしても良い。
【０１１５】
補間処理された画素を重ね合わせたら、ステップＳＴ１１０ではＲＧＢからＣＭＹＫへの色座標を変換するために色補正を実行し、ステップＳＴ１１２ではカラープリンタ１７ｂにおける階調表現が二階調であることに鑑みてハーフトーン処理を実行する。そして、ステップＳＴ１１４ではカラープリンタ１７ｂに対して印刷データを出力することになる。
【０１１６】
以上はプリンタドライバ１２ｃについて説明しているが、ディスプレイドライバ１２ｂについても同様に実行可能である。
【０１１７】
このように、メタコマンドに対応して生成される画素について元のメタコマンドを考慮して補間処理することにより、補間処理した画像自体は向上するもののその境界領域が隣接画素と一致しなくなる不自然さを解消すべく、非メタコマンド画素については境界を延長して補間処理するととともに、両者の重なり部分でメタコマンド画素を優先させるようにしたため、延長された境界のほとんどは隣接領域の下地となって隠れてしまいつつも、境界形状の変化が生じた場合には背景画素が生じてしまうことを防止することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態にかかる画像データ補間装置のクレーム対応図である。
【図２】同画像データ補間装置の具体的ハードウェアのブロック図である。
【図３】本発明の画像データ補間装置の他の適用例を示す概略ブロック図である。
【図４】本発明の画像データ補間装置におけるメインフローチャートである。
【図５】仮想描画面への書き込みを示す模式図である。
【図６】仮想描画面での色情報と属性情報の対比を示す模式図である。
【図７】キュービック法の概念図である。
【図８】ニアリスト法の概念図である。
【図９】ニアリスト法で各格子点のデータが移行される状況を示す図である。
【図１０】ニアリスト法の補間前の状況を示す概略図である。
【図１１】ニアリスト法の補間後の状況を示す概略図である。
【図１２】バイリニア法の概念図である。
【図１３】補間関数の変化状況を示す図である。
【図１４】色情報仮想描画面に書き込まれた文字画像を示す図である。
【図１５】パターンマッチングによって補間情報を得る状況を示す図である。
【図１６】文字において生じるノイズのドットをパターンマッチングによって消去する過程を示す図である。
【図１７】倍率が異なる場合のパターンマッチングによって補間情報を得る状況を示す図である。
【図１８】パターンマッチングによって色の割り振り情報を含む補間情報を得る状況を示す図である。
【図１９】パターンマッチングの具体的データ処理手法を示す図である。
【図２０】本発明の画像データ補間装置における非メタコマンド画素の補間処理のフローチャートである。
【図２１】本発明の画像データ補間装置におけるメタコマンド画素の補間処理のフローチャートである。
【図２２】画像データを種別毎に読み出す状況と境界延長処理を示す図である。
【図２３】画像データを種別毎にバッファに読み出す状況を示す図である。
【図２４】境界延長処理で境界が延長する状況を示す図である。
【符号の説明】
１０…コンピュータシステム
１１ａ…スキャナ
１１ｂ…デジタルスチルカメラ
１１ｃ…ビデオカメラ
１２…コンピュータ本体
１２ａ…オペレーティングシステム
１２ｂ…ディスプレイドライバ
１２ｂ…ドライバ
１２ｃ…プリンタドライバ
１２ｄ…アプリケーション
１３ａ…フロッピーディスクドライブ
１３ｂ…ハードディスク
１３ｃ…ＣＤ−ＲＯＭドライブ
１４ａ…モデム
１５ａ…キーボード
１５ｂ…マウス
１７ａ…ディスプレイ
１７ａ１…ディスプレイ
１７ｂ…カラープリンタ
１７ｂ１…カラープリンタ
１７ｂ２…カラープリンタ
１９ａ…ネットワークコンピュータ
１９ｂ…テレビモニタ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image data interpolation device for interpolating image data composed of pixels in a dot matrix, an image data interpolation method, and a medium on which an image data interpolation program is recorded.
[0002]
[Prior art]
When an image is handled by a computer or the like, the image is represented by dot matrix pixels, and each pixel is represented by a gradation value. For example, photographs and computer graphics are often displayed on a computer screen with 640 dots in the horizontal direction and 480 dots in the vertical direction.
[0003]
On the other hand, the performance of color printers has been remarkably improved, and the dot density is extremely high, such as 720 dpi. In this case, when an image of 640 × 480 dots is printed in correspondence with each dot, the size becomes extremely small. In this case, since the tone value is different and the meaning of the resolution itself is different, it is necessary to interpolate between dots and convert the data into printing data.
[0004]
Conventionally, as a method of interpolating dots in such a case, a nearest neighbor interpolation method (hereinafter, referred to as a nearest neighbor method) or a cubic convolution interpolation method (a cubic convolution interpolation: hereinafter, A method such as the cubic method) is known. Japanese Patent Application Laid-Open No. 6-225140 discloses a technique in which a dot pattern is prepared so as to form an enlarged form in which the edge is smooth when smoothing the edge when dots are interpolated. ing.
[0005]
[Problems to be solved by the invention]
The above-described conventional interpolation technique has the following problems.
[0006]
Various methods such as the near-list method and the cubic method have advantages and disadvantages depending on the type of processing target. On the other hand, recently, a single document to be printed often includes a plurality of types of processing targets. Of the quality will be reduced.
[0007]
On the other hand, in the invention disclosed in Japanese Patent Application Laid-Open No. 6-225140, the number of patterns is enormous on the premise of a color image, and it is difficult to prepare in advance.
[0008]
Further, when generating a pixel with a low resolution, a noise pixel may be generated due to an arithmetic error or the like in the meta command pixel, but the noise pixel is accurately enlarged by the interpolation process.
[0009]
The present invention has been made in view of the above problems, and has an image data interpolation apparatus, an image data interpolation method, and an image data interpolation program capable of obtaining a good-looking interpolation result when a plurality of types of processing targets are included. The purpose of this is to provide a medium on which is recorded.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, image data corresponding to a meta-command and other image data are input and rendered in a virtual area in a predetermined order while being distinguishable from each other. Virtual rendering means, and non-meta-command pixel interpolation means for performing interpolation processing so as to obtain a predetermined interpolation magnification by expanding the peripheral area when reading pixels corresponding to image data other than the meta-command from the virtual area, A meta command pixel interpolating means for generating an interpolated pixel corresponding to an original meta command when reading a pixel corresponding to a meta command from the virtual area and performing an interpolation process at the interpolation magnification; The interpolation result of the pixel interpolation means and the interpolation result of the meta command pixel interpolation means are synthesized, and the There interpolation result of de-pixel interpolation means a structure comprising a superposition means for priority.
[0011]
In the invention according to claim 1 configured as described above, when the virtual drawing means inputs the image data corresponding to the meta command and the other image data, they are superimposed in a predetermined order so that they can be identified. To draw in the virtual area. Then, the non-meta-command pixel interpolating means reads out the pixels corresponding to the image data other than the meta-command from the virtual area and performs the interpolation processing so as to have a predetermined interpolation magnification. To process. Therefore, an interpolated image wider than the original area is obtained. On the other hand, the meta command pixel interpolating means also reads out the pixel corresponding to the meta command from the virtual area and performs the interpolation processing so as to have the above interpolation magnification. The interpolation pixel is generated as follows. The superposition means combines the interpolation result of the non-metacommand pixel interpolation means with the interpolation result of the metacommand pixel interpolation means, and gives priority to the interpolation result of the metacommand pixel interpolation means in the overlapping portion.
[0012]
That is, although the image of the metacommand is a group of pixels in a so-called dot matrix in the virtual area, the interpolation process has a smooth contour shape corresponding to the original metacommand in the interpolation process. It has to be changed from before interpolation processing. If the shape of the contour changes, there may be a portion that overlaps at the boundary with an image other than the adjacent meta command, or a portion where a gap may occur. On the other hand, since images other than the meta-command are generated wider than originally expected, a gap is less likely to occur, and a smooth contour shape remains because the meta-command image is prioritized in the overlapping portion. Will be.
[0013]
Here, the meta command means a command that indicates the shape in a vector. Therefore, in the case of a drawing application, the command is interpreted to draw a figure or the like, and the image quality does not deteriorate even if the enlargement or reduction is repeated. On the other hand, in other images, information of each pixel is given at the time of drawing, and the information is lost at the time of reduction, and does not return to the original state even if it is enlarged. In this sense, the metacommand targets not only images but also characters.
[0014]
Even a metacommand having such a property cannot always maintain its characteristics as a process in a computer. Therefore, if it is represented as a set of pixels at a certain point in time, the subsequent processing is inevitably subjected to the same processing as other images. However, if it is known whether or not the image has been drawn by the meta command, there is room for changing the interpolation method in the expanding interpolation processing. For example, in the case of a meta command, it is considered that the boundary should be substantially smoothed for interpolation. On the other hand, it is not always possible to determine whether smoothing is appropriate for other images. Therefore, if the interpolation processing is performed according to different policies, the boundary shape after the interpolation processing may deviate. The present invention has been created against such a background.
[0015]
On the other hand, the virtual drawing means draws in the virtual area based on the image data corresponding to the meta command and the other image data, and each of them can be identified. Various methods can be adopted as a method of making such identification possible. For example, an attribute area may be separately provided so that the type of each data in the virtual area can be written, or The attribute may be embedded in the data. When the number of colors can be reduced, a certain bit can be assigned to an attribute.
[0016]
The non-meta-command pixel interpolating means reads out the pixels corresponding to the image data other than the meta-command from the virtual area and performs an interpolation process. For example, if the type of the image data can be determined from the attribute area, the pixel corresponding to the image data other than the meta command is read out while selecting with reference to the attribute area, and the pixel is interpolated by the corresponding interpolation processing.
[0017]
Various types of interpolation processing can be adopted. For example, the cubic interpolation processing is appropriate for natural images, and the near-list method is appropriate for non-natural images such as computer graphics. .
[0018]
The non-meta-command pixel interpolating means expands the peripheral area to perform the interpolation processing, and various specific processings are performed for expanding the peripheral area. As an example, the invention according to claim 2 is the image data interpolation device according to claim 1, wherein the non-metacommand pixel interpolation unit converts the information of the pixels in the peripheral area into the information of the pixels outside the area. There is a configuration to use.
[0019]
In the invention according to claim 2 configured as described above, the peripheral area is expanded, but there is no pixel information there. Therefore, the information of the pixels in the peripheral area is used as the information of the pixels in the expanded area. . Therefore, the information may be copied and used as it is, or may be copied while being changed step by step. Further, copying may be performed in the work area, and it is sufficient that the copying machine is used substantially without actually performing the copying operation. Although the size of the area to be expanded in this way is not particularly limited, it depends on the unevenness of the boundary generated when the metacommand pixel interpolating unit generates a pixel, and a concave portion occurs in the pixel of the metacommand. It suffices if the gap does not occur at the time of superposition. For example, when pixel information is read line by line from the virtual area, a process of expanding both ends of the pixel of the meta command by one pixel is sufficient.
[0020]
The meta command pixel interpolation means also selects and reads out a pixel corresponding to the meta command from the virtual area. This meta command pixel interpolation means generates an interpolation pixel so as to correspond to the original meta command. For example, when considered as an image, it may correspond to smooth boundaries or sharp corners.
[0021]
On the other hand, a metacommand representing a character includes graphic information that is complicatedly bent in a small area, and therefore has a feature that extra dots are likely to occur due to calculation accuracy when generating pixels. As a preferred example in view of such a feature, the invention according to claim 3 is the image data interpolation device according to any one of claims 1 and 2, wherein the meta command pixel interpolation means represents a character. In performing the interpolation processing of the meta-command, a configuration is adopted in which noise pixels at the time of pixel generation based on the meta-command are deleted and pixel interpolation is performed.
[0022]
In the invention according to claim 3 configured as described above, when generating a pixel based on a metacommand representing a character, it is determined whether or not the pixel is a noise pixel. Is erased and pixel interpolation is performed. Whether or not the pixel is a noise pixel can be generally determined from the characteristics of the character. For example, one pixel protrudes even though it is a straight line portion, there is a pixel that protrudes unnaturally at a portion where two sides intersect, or there is a pixel that protrudes unnaturally at the end of a curved portion. That is, it means a pixel or the like that can be generated around a connected part when a character is represented by a plurality of vector data.
[0023]
In addition, since the interpolation process is a two-dimensional process, it is necessary to read pixels correspondingly when reading from a virtual area. As an example, the invention according to claim 4 is the image data interpolation apparatus according to any one of claims 1 to 3, wherein the meta-command pixel interpolation means reads a plurality of lines from the virtual area when reading the pixels from the virtual area. It is configured to read the pixels of the minute and perform the interpolation processing.
[0024]
In the invention according to claim 4 configured as described above, in order to implement two-dimensional interpolation processing, image data of a plurality of lines is read and subjected to interpolation processing.
[0025]
Various kinds of interpolation processing can also be adopted by the meta command pixel interpolation means. However, the process can be classified in advance in order to generate the interpolated pixel so as to correspond to the original metacommand, for example, by considering the presence or absence of the noise pixel as described above. As a preferred example in such a case, the invention according to claim 5 is the image data interpolation device according to claim 4, wherein the meta command pixel interpolation means determines whether or not pixel information exists in an area of a predetermined size. Pattern data that includes corresponding pattern data and interpolated pixel information of a predetermined interpolation magnification corresponding to each pattern data, reads out the pixels of the corresponding area from the virtual area, sets it as comparison data, and matches the pattern data to match the pattern data Is configured to perform an interpolation process based on the interpolation pixel information prepared corresponding to.
[0026]
In the invention according to claim 5 configured as described above, an interpolation process is executed by pattern matching for a small area having a predetermined size. That is, pattern data corresponding to the presence or absence of pixel information is prepared corresponding to the same area, and pixels in the corresponding area are read out from the virtual area and used as comparison data. Then, interpolation processing is performed based on interpolation pixel information of a predetermined interpolation magnification prepared corresponding to the pattern data subjected to pattern matching. Therefore, it is possible to prepare the pixel of the noise that can be expected as the pattern data, and prepare the interpolation pixel information in which the noise pixel is deleted corresponding to the pattern data.
[0027]
In such pattern matching, when performing a new pattern matching by moving the attention area, it is complicated to update all the comparison data. For this reason, the invention according to claim 6 is the image data interpolation device according to claim 5, wherein the meta command pixel interpolating means includes a rectangular area having the number of pixels corresponding to a data width that can be simultaneously processed. The configuration is such that a new pixel row in the direction in which the target rectangular area is moved is incorporated into the comparison data by a first-in first-out process, and matching with the pattern data is continued.
[0028]
In the invention according to claim 6 configured as described above, if the rectangular area has the number of pixels with respect to the data width that can be processed simultaneously, pattern matching can be performed by one operation for one area. Further, when performing new pattern matching by moving the attention area, it is not always necessary to update all the comparison data, and a new pixel row in the moving direction is incorporated into the comparison data by first-in first-out processing. More specifically, the pattern matching of 4 × 4 pixels is compared with the pattern data of 16 pixels. If this square area is moved by one pixel, the information of the pixels in three rows is substantially changed. Instead, the presence / absence of four pixels in one row on the front side in the movement direction is included as comparison data, and the presence / absence of four pixels in one row on the rear side is excluded. Therefore, by first-in-first-out of the comparison data for the four pixels, it is not necessary to update all the comparison data.
[0029]
If pattern matching is to be applied to a color image, it cannot be determined only by the presence or absence of pixels, so that it would be impractical to prepare pattern data for each color. On the other hand, according to a seventh aspect of the present invention, in the image data interpolating device according to any one of the fifth and sixth aspects, the meta command pixel interpolating means uses the interpolation pixel information corresponding to the pattern data as It is configured to include color allocation information of each pixel in the comparison data.
[0030]
In the invention according to claim 7 configured as described above, the pattern data is matched with the comparison data indicating the presence or absence of a pixel, but the interpolation pixel information referred to in the case of matching includes color allocation information. Therefore, this allocation realizes interpolation by pattern matching for a substantially color image.
[0031]
On the other hand, the superposition means combines the interpolation result of the non-metacommand pixel interpolation means with the interpolation result of the metacommand pixel interpolation means, and gives priority to the interpolation result of the metacommand pixel interpolation means in the overlapping portion.
[0032]
As one example of the process of giving priority to one of the above, the invention according to claim 8 is the image data interpolation device according to any one of claims 1 to 7, wherein the superimposing unit includes the non-metacommand pixel. After the interpolation result of the interpolation means is first written into a predetermined area, pixels other than the background pixel in the interpolation result of the meta command pixel interpolation means are overwritten.
[0033]
In the invention according to claim 8 configured as described above, if the interpolation result of the non-metacommand pixel interpolation unit and the interpolation processing result of the metacommand pixel interpolation unit are temporarily held in different areas, What is necessary is just to superimpose the interpolation processing result held in the area in a predetermined order, and to write the interpolation result in the output area while sequentially performing the interpolation processing according to the predetermined order. Is also good.
[0034]
In this way, for image data other than the meta-command, the peripheral area is expanded, and for image data corresponding to the meta-command, an interpolation pixel is generated so as to correspond to the original meta-command. The method of giving priority to the corresponding image data is not necessarily limited to a substantial device, and it can be easily understood that the method also functions as the method.
[0035]
For this reason, the invention according to claim 9 is an image data interpolation method for increasing the number of constituent pixels based on image data in which an image is represented by a dot matrix pixel and drawn, wherein the image data corresponding to the meta command is provided. And a step of inputting image data other than the above and drawing them in a predetermined order so as to be identifiable, and a peripheral area when reading pixels corresponding to image data other than the meta command from the virtual area. A step of performing interpolation processing so as to have a predetermined interpolation magnification after expanding the pixel, and reading out a pixel corresponding to the meta command from the virtual area and performing the interpolation processing so as to have the interpolation magnification according to the original meta command. Generating the interpolated pixel so as to perform the interpolation and the interpolation corresponding to the meta command in the overlapping portion when synthesizing the interpolation result based on both steps. It is constituted comprising a step of synthesizing give priority to the fruit.
[0036]
In other words, there is no difference that the present invention is not necessarily limited to a substantial device and is effective as a method.
[0037]
By the way, such an image data interpolating device may exist alone or may be used in a state of being incorporated in a certain device. The idea of the present invention is not limited to this, but includes various aspects. It is a thing. Therefore, it can be changed as appropriate, such as software or hardware.
[0038]
When the software of the image data interpolating device is realized as an example of realizing the idea of the present invention, it naturally exists on a recording medium on which such software is recorded, and it must be said that the software is used.
[0039]
As an example, the invention according to claim 10 is an interpolation processing program that executes an interpolation process by a computer so as to increase the number of constituent pixels based on image data that is rendered by expressing an image by dot matrix pixels. A step of inputting image data corresponding to the metacommand and other image data and superimposing them in a predetermined order so that they can be identified; and When reading out the pixels corresponding to the image data other than the above, expanding the peripheral area and performing an interpolation process so as to have a predetermined interpolation magnification, and reading out the pixels corresponding to the meta command from the virtual area and performing the interpolation magnification Generating an interpolated pixel so as to correspond to the original meta-command when performing the interpolating process so that In the overlapping portion in the synthesis of the results and it is constituted comprising the step of combining by priority to interpolation results corresponding to the meta-command.
[0040]
Of course, the recording medium may be a magnetic recording medium or a magneto-optical recording medium, and any recording medium to be developed in the future can be considered in the same manner. Further, the duplication stages of the primary duplicated product, the secondary duplicated product and the like are equivalent without any question.
[0041]
Further, even when a part is implemented by software and a part is implemented by hardware, there is no difference in the concept of the invention, and a part is stored on a recording medium and appropriately It may be in a form that can be read.
[0042]
【The invention's effect】
As described above, according to the present invention, even if a process of actively performing smoothing of a boundary shape in an image interpolation process for a meta command is performed, a gap or the like does not occur at a boundary portion, so that a good-looking interpolation result can be obtained. Can be provided.
[0043]
Further, according to the second aspect of the invention, the process of expanding the peripheral area is simplified.
[0044]
Furthermore, according to the third aspect of the present invention, it is possible to eliminate noise pixels that are likely to appear in meta commands representing characters.
[0045]
Further, according to the fourth aspect of the present invention, the interpolation processing can be realized by reading the image data of a plurality of lines.
[0046]
Further, according to the invention according to claim 5, it is easy to realize the interpolation processing corresponding to the original meta-command in the interpolation processing by the pattern matching.
[0047]
Furthermore, according to the invention of claim 6, pattern matching can be performed extremely easily and efficiently.
[0048]
Further, according to the seventh aspect of the present invention, it is possible to perform an interpolation process by pattern matching even in a color image.
[0049]
Further, according to the invention according to claim 8, the adjustment is made according to the order, so that the processing is simplified.
[0050]
Further, according to the ninth aspect of the invention, it is possible to provide an image data interpolation method having the same effect, and according to the tenth aspect of the invention, it is possible to provide a medium recording an interpolation processing program having the same effect. .
[0051]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0052]
FIG. 1 is a claim correspondence diagram showing the image data interpolation device of the present invention.
[0053]
In data processing performed by a computer or the like, an image is represented by pixels in a dot matrix, and image data is composed of a group of data representing each pixel. The image here is not limited to a so-called bitmap image such as a photograph or a computer graphic, but also includes an image drawn by a so-called meta command such as a character or a business graph. Although both bitmap-based images and meta-command-based images are common in the sense that they are images, the drawing properties are slightly different, and the compatibility with the interpolation processing is different depending on the properties.
[0054]
In view of such a difference in the drawing properties, when the virtual drawing means C1 inputs the image data corresponding to the meta command and the other image data, they are superimposed in a predetermined order so as to be identifiable in the virtual area. draw. Then, the non-meta-command pixel interpolation means C2 reads out the pixels corresponding to the image data other than the meta-command from the virtual area and performs the interpolation processing so as to have a predetermined interpolation magnification. Perform interpolation processing. Therefore, an interpolated image wider than the original area is obtained. On the other hand, the meta command pixel interpolating means C3 also reads out the pixel corresponding to the meta command from the virtual area and performs the interpolation processing so as to have the interpolation magnification. Is generated so as to correspond to. The superimposing means C4 combines the interpolation result of the non-metacommand pixel interpolating means C2 with the interpolation result of the metacommand pixel interpolating means C3. Priority.
[0055]
In the present embodiment, the computer system 10 is employed as an example of hardware for realizing such an image data interpolation device.
[0056]
FIG. 2 shows the computer system 10 in a block diagram.
[0057]
The computer system 10 includes a scanner 11a, a digital still camera 11b, and a video camera 11c as image input devices, and is connected to a computer main body 12. Each input device is capable of generating image data representing an image by dot matrix pixels and outputting the image data to the computer main unit 12. Here, the image data is displayed in 256 gradations in three primary colors of RGB. , About 16.7 million colors can be expressed.
[0058]
The computer main body 12 is connected to a floppy disk drive 13a, a hard disk 13b, and a CD-ROM drive 13c as external auxiliary storage devices. The hard disk 13b stores main programs related to the system. Necessary programs and the like can be appropriately read from a CD-ROM or the like.
[0059]
Also, a modem 14a is connected as a communication device for connecting the computer main body 12 to an external network or the like. The modem 14a is connected to the external network via the same public communication line, and software and data can be downloaded and introduced. Has become. In this example, the modem 14a accesses the outside through a telephone line. However, a configuration in which a network is accessed through a LAN adapter is also possible. In addition, a keyboard 15a and a mouse 15b for operating the computer main body 12 are also connected.
[0060]
Further, a display 17a and a color printer 17b are provided as image output devices. The display 17a has a display area of 800 pixels in the horizontal direction and 600 pixels in the vertical direction, and can display the above-mentioned 16.7 million colors for each pixel. Of course, this resolution is merely an example, and can be changed as appropriate, such as 640 × 480 pixels or 1024 × 720 pixels.
[0061]
The color printer 17b is an ink jet printer, and is capable of printing an image with dots on printing paper as a recording medium using four color inks of CMYK. The image density can be printed at a high density of 360 × 360 dpi or 720 × 720 dpi, but the gradation table has a two-gradation expression such as whether or not to apply color ink.
[0062]
On the other hand, a predetermined program is executed in the computer main body 12 in order to display or output an image output device while inputting an image using such an image input device. Of these, an operating system (OS) 12a is operating as a basic program, and the operating system 12a performs a print output to a display driver (DSP DRV) 12b for displaying on a display 17a and a color printer 17b. A printer driver (PRT DRV) 12c to be installed is incorporated. These drivers 12b and 12c depend on the model of the display 17a and the color printer 17b, and can be additionally changed to the operating system 12a according to each model. In addition, additional functions beyond standard processing can be realized depending on the model. That is, it is possible to realize various additional processes within an allowable range while maintaining a common processing system on the standard system of the operating system 12a.
[0063]
The application 12d is executed on the operating system 12a as the basic program. The processing contents of the application 12d are various, monitor the operation of the keyboard 15a and the mouse 15b as operation devices, and when operated, appropriately control various external devices to execute corresponding arithmetic processing, Further, the processing result is displayed on the display 17a or output to the color printer 17b.
[0064]
In the computer system 10, a photograph or the like can be read by the scanner 11a, which is an image input device, to acquire image data. The application 12d such as a word processor can paste not only sentences but also read photographic images or paste a business graph based on a spreadsheet result. The integrated document created in this manner can be displayed and output on a display 17a or a color printer 17b as an image output device. Such an integrated document is different in terms of characters, photographs, and business graphs, but is common in that an image is formed by a collection of pixels.
[0065]
In displaying the integrated document, the pixels displayed on the display 17a cannot correspond to the pixels of the color printer 17b as they are. This is because the pixel density generated by the application 12d and displayed on the display 17a does not match the pixel density of the color printer 17b. Of course, they may coincide with each other, but in many cases, the pixel density of the color printer 17b whose pixel density is improved for higher image quality is higher than that of the general display 17a. It is.
[0066]
For this reason, resolution conversion is performed in order to eliminate the difference in the actual pixel density of each device while determining the reference pixel density in the operating system 12a. For example, when the resolution of the display 17a is 72 dpi and the operating system 12a is based on 360 dpi, the display driver 12b performs resolution conversion between the two, and the resolution of the color printer 17b is 720 dpi. If there is, the printer driver 12c performs resolution conversion.
[0067]
Since the resolution conversion corresponds to a process of increasing the number of constituent pixels in image data, it corresponds to an interpolation process, and the display driver 12b and the printer driver 12c perform the interpolation process as one of the functions.
[0068]
In the present embodiment, as described in detail below, the display driver 12b or the printer driver 12c writes an image in a virtual area based on input image data. And other pixels can be distinguished. Then, pixels are read out from the virtual screen for each type, interpolated by an appropriate interpolation method and superimposed to generate a final image, which is output to the display 17a and the color printer 17b.
[0069]
In this sense, the display driver 12b and the printer driver 12c constitute the above-described virtual drawing means C1, non-metacommand pixel interpolating means C2, metacommand pixel interpolating means C3, and superimposing means C4. The display driver 12b and the printer driver 12c are stored in the hard disk 13b, and are read and operated by the computer main body 12 at the time of startup. At the time of introduction, it is recorded on a medium such as a CD-ROM or a floppy disk and installed. Therefore, these media constitute a medium on which the image data interpolation program is recorded.
[0070]
In the present embodiment, the image data interpolation device is realized as the computer system 10, but such a computer system is not always required. Similarly, the pixel drawn by the meta command and the other pixels are not used. Any system that requires interpolation processing may be used. For example, FIG. 3 shows a network computer 19a, which is connected to an external wide area network via a public telephone line or the like. In such a wide area network, image data having various different drawing characteristics including character information and photographic images are transmitted and received. The network computer 19a acquires such image data and displays it on the television monitor 19b as appropriate, or displays the image data. Can output to a printer that does not. Also in this case, when it is necessary to convert the image resolution, or when the operator wants to enlarge a part by his / her intention, the image is displayed by performing interpolation processing corresponding to an operation such as zooming.
[0071]
Further, the interpolation processing may be performed not on the computer side but on the display output device side. In the case of a color printer, for example, print data in a script format may be input, and the above-described interpolation processing may be executed when the print data is adjusted to its own print resolution.
[0072]
FIG. 4 shows a software flow related to the resolution conversion executed by the printer driver 12c described above.
[0073]
In step ST102, image data is input and sorted according to the superposition. That is, an image read from the scanner 11a by the application 12d, characters input by the keyboard 15a, and a business graph created by spreadsheet software are combined as one integrated document. In this case, overlapping occurs. In particular, in the field of DTP, images and characters are often superimposed directly to create a single picture, but in this case, superposition is complicated. Of course, the superimposed lower layer image is not visible, but exists on the data, and the data is again superimposed in the printer driver 12c. The concept of a layer is used when each image is superimposed, and the commands of the image data are sorted so as to be arranged in the upper and lower layers, and the image data is prepared for writing from the lower layer.
[0074]
In the next step 104, based on the image data rearranged in this way, writing is performed on a virtual drawing surface as a virtual area. This writing on the virtual drawing surface is schematically shown in FIG. After the commands of the image data are sorted based on the arrangement of the layers, the corresponding drawing functions are called to write data for each pixel in the color information virtual drawing surface and the attribute information virtual drawing surface allocated to the memory. In the color information virtual rendering surface, three bytes corresponding to the red, green, and blue color components are allocated to each pixel, and a memory area for the number of pixels in the horizontal direction × the number of pixels in the vertical direction is allocated.
[0075]
On the other hand, the attribute information virtual rendering surface enables each pixel to determine whether it is “character (C)” or “business graph (B)” among the “non-metacommand pixel (N)” and the metacommand pixel. One byte is assigned to each pixel and attribute identification codes ("N", "C", "B") are written. Specifically, here, the bitmap image data is processed as non-metacommand pixels. Bitmap image data includes not only photographs but also computer graphics. In particular, these may be divided and the interpolation process may be changed, or a constant interpolation process may be applied uniformly. It is possible to distinguish image or computer graphics by analyzing image data.For example, when the number of colors used is large, it is determined to be a natural image, and when the number of colors used is small, It can also be determined as a non-natural image. This is because a natural image is counted as a plurality of colors even if the object has the same color due to shading or the like.
[0076]
FIG. 6 shows the correspondence between the color information virtual drawing surface written in this way and the attribute information virtual drawing surface. Assuming one horizontal line at the reference resolution, the color of the pixel is written for each pixel and the type of the pixel is also written. Therefore, it is possible to select a pixel of a non-metacommand pixel, a pixel of a character, or a pixel of a business graph from the write information of the attribute information.
[0077]
In this example, the attribute information is written on the virtual drawing surface separately from the color information. However, the present invention is not necessarily limited to such a method. For example, another byte may be used as attribute information in addition to the color information, and 4 bytes may be assigned to each pixel. Further, a screen for writing the overlay information and a screen for writing the color information for each type may be separated, and the overlay may be performed with reference to the overlay information at the time of the overlay.
[0078]
In step ST106, image data is read from the virtual drawing surface shown in FIG. 5 for each type of image, and an optimal interpolation process according to the type of image is executed. Here, each method of the interpolation processing prepared in the present embodiment will be described.
[0079]
As an interpolation process suitable for a natural image such as a photograph, which is an example of a non-metacommand pixel, an interpolation process using a cubic method can be executed. As shown in FIG. 7, the cubic method uses data of a total of 16 grid points including not only four grid points surrounding a point Puv to be interpolated but also grid points around one point. A general expression using a cubic convolution function is as follows.
[0080]
(Equation 1)

[0081]
It becomes.
[0082]
The cubic method has a feature that the gradual change gradually occurs as one grid point approaches the other grid point, and the degree of the change becomes a so-called cubic function.
[0083]
As an interpolation process suitable for a non-natural image such as computer graphics, which is another example of a non-metacommand pixel, a near-list interpolation process can be executed. In the near-list method, as shown in FIG. 8, the distance between the surrounding four grid points Pij, Pi + 1j, Pij + 1, Pi + 1j + 1 and the point Puv to be interpolated is obtained, and the data of the closest grid point is transferred as it is. If this is represented by a general formula,
Puv = Pij
Here, i = [u + 0.5} and j = [v + 0.5}. [] Indicates that a Gaussian symbol takes an integer part.
[0084]
FIG. 9 shows a situation where the number of pixels is vertically and horizontally tripled by the near-list method. For the pixel to be interpolated, the data of the closest pixel among the first four corner pixels is transferred as it is. Therefore, the original image in which black pixels are arranged obliquely with white pixels as a background as shown in FIG. 10 has a relationship in which black pixels are arranged three times vertically and horizontally and obliquely as shown in FIG. Is held.
[0085]
The near-list method has a feature that an edge of an image is held as it is. Therefore, if the image is enlarged, the edge is retained as an edge although the shaggy is conspicuous. On the other hand, in other interpolation processing, the pixel to be interpolated is changed smoothly using data of surrounding pixels. Therefore, while shaggy is not conspicuous, the information of the original image is cut off, and edges are lost, which is not suitable for non-natural images such as computer graphics and business graphs.
[0086]
In the present embodiment, the above-described near-list method and cubic method are used. However, in order to understand these characteristics, another interpolation method, a bilinear interpolation method (bilinear interpolation: hereinafter, referred to as a bilinear method). ) Will be described.
[0087]
The bilinear method is similar to the cubic method in that it gradually changes from one grid point to the other as shown in FIG. 12, but the change depends only on the data of the grid points on both sides. In that it is linear. That is, a region partitioned by four grid points Pij, Pi + 1j, Pij + 1, and Pi + 1j + 1 surrounding a point Puv to be interpolated is divided into four partitions by the interpolated point Puv, and data on diagonal positions is weighted by the area ratio. I do. Expressing this as an equation,
P = {(i + 1) -u} (j + 1) -v} Pij
+ ｛(I + 1) -u｝ ｛v-j｝ Pij + 1
+ {U-i} (j + 1) -v @ Pi + 1j
+ ｛U-i｝ ｛v-j｝ Pi + 1j + 1
It becomes. Note that i = [u] and j = [v].
[0088]
Both the cubic method and the bilinear method are common in that they gradually change from one grid point to the other grid point, but whether the change is a cubic function or a linear function. Differently, when viewed as an image, the difference is large. FIG. 13 is a diagram two-dimensionally showing the difference between the interpolation results in the near-list method, the cubic method, and the bilinear method in order to facilitate understanding. In the figure, the horizontal axis indicates the position, and the vertical axis indicates the interpolation function. Grid points exist at positions of t = 0, t = 1, and t = 2, and interpolation points are at positions of t = 0 to 1.
[0089]
In the case of the bilinear method, since the boundary only changes linearly between two adjacent points (t = 0 to 1), the boundary is smoothed, and the impression of the screen is blurred. That is, unlike the smoothing of the corners, when the boundary is smoothed, the contour which should be originally in computer graphics disappears, and the focus becomes loose in a photograph.
[0090]
On the other hand, in the cubic method, not only the two points adjacent to each other (t = 0 to 1) draw a chevron-shaped protrusion but gradually approach each other, and further, the outside (t = 1 to 2) between the two points. It has the effect of pushing down. That is, a certain edge portion is changed so as to have a large difference in height such that no step is formed, and this has a favorable effect that in a photograph, no step is formed while increasing sharpness. However, in computer graphics, the meaning of an edge does not mean an analog change, so it is not preferable.
[0091]
Next, a description will be given of an interpolation process of pattern matching suitable for the meta-command pixel.
[0092]
FIG. 14 shows a character image written on the color information virtual drawing surface. Characters are also composed of dot matrix pixels arranged in the horizontal direction and the vertical direction. As shown in FIG. 15, dots (●) become image pixels and dots (dots) represent backgrounds as shown in FIG. Pixel.
[0093]
In the pattern matching, 16 pixels, which is a square area of 4 × 4 pixels as shown in FIG. 15, are matched as one area with pattern data prepared in advance, and a square area of 4 pixels of 2 × 2 pixels on the inside is matched. , An interpolation pixel is generated. The reason why the reference is made to the pixels on the one side outside even though it is a square area of four pixels is that the interpolation result for the square area of four pixels also changes depending on the presence or absence of surrounding pixels. FIG. 15 also shows two pattern data that match when viewed as four pixels, but differ when viewed as sixteen pixels. In pattern data A, dots are arranged vertically and project one dot horizontally. In the pattern data B, dots are not added around the pattern data B, and dots are added to three of the four pixels. In the pattern data A, it is preferable to use a chevron-shaped dot as a whole in order to show a protruding image, but it is preferable to use a three-pixel pattern so as to represent a triangle. Therefore, the corresponding interpolated pixel patterns also differ.
[0094]
By the way, when calling a drawing function according to image data and writing data for each pixel to the color information virtual drawing surface and the attribute information virtual drawing surface, pixels to be written are specified for non-metacommand pixels, For the meta-command pixel, the pixel to be written by the drawing function is obtained by calculation. Due to such a property, it is possible to draw a graphic of an arbitrary size by changing the parameter of the command on the application 12d side. However, when a plurality of commands correspond to one figure like a character, a pixel as noise may be generated. In other words, dots are not generated at a certain magnification, but meaningless dots are generated at another magnification. In particular, it is likely to occur at a connection point of a line drawn by a plurality of commands. Of course, it is preferable that there is no dot as such noise.
[0095]
FIG. 16 shows a method of eliminating dots as noise employed in the present embodiment. FIG. 3A shows an original image. Although a part of the character is shown, it can be seen that it is a corner of a frame-like figure, and it can be imagined that it is a connection point of a plurality of drawing commands. Of course, it is not always necessary to be a connection point.
[0096]
Looking at the dot surrounded by the two-dot chain line, it does not seem that this dot is particularly necessary. This is because other portions seem to show a line having a width of 2 dots, and it is difficult to assume that it is necessary to attach a dot that protrudes at the corner. That is, it seems appropriate to judge that this dot should not be added as shown in FIG. Of course, such a determination cannot be made simply when the area becomes smaller. However, in a case where 16 pixels are collectively compared with the pattern data as in the present embodiment, such a determination can be made incidentally. It becomes.
[0097]
Under such a premise, the interpolated pixel information on the assumption that there is no dot as shown in FIG. Let it be. Then, through the pattern matching, the pixel as noise generated when the meta command pixel is interpreted and drawn, as if it were found and deleted in the conversion process, and correspond to the original meta command pixel. Thus, the same result as when the interpolated pixel is generated can be obtained.
[0098]
Obviously, such dot elimination can be applied to metacommands in general. Therefore, if a dot that appears to be noise occurs in a square range of 16 pixels, the pattern data may be associated with interpolation pixel information as if the dot had been deleted. However, a character has a special feature that a large number of drawing commands are applied to a small area. Therefore, it can be said that a dot as a noise is easily generated, and the noise is relatively easily specified.
[0099]
A plurality of sets of interpolated pixel patterns are prepared for each magnification, and FIG. 17 shows an example of a case where the set is 1.5 times in the vertical and horizontal directions.
[0100]
By the way, if pattern matching is to be made to correspond to color data, an extremely large number of pattern data must be prepared even for an example of four pixels. That is, a combination corresponding to the permutation of the number of possible colors of each pixel occurs. However, in the present embodiment, the problem was solved by comparing patterns based on the presence or absence of dots and assigning colors to correspond to color data. FIG. 18 shows an example. The comparison with the pattern data of 16 pixels is performed in the same manner as in the previous example. For 4 pixels, the color of each pixel is assigned to which of the interpolation pixels. As a result, pre-processing for determining the color of the interpolation pixel is not required, and the number of pattern data is reduced, so that the processing amount and the resource amount are extremely reduced.
[0101]
On the other hand, FIG. 19 shows a more specific method of pattern matching based on 16 pixels. FIG. 9A shows the arrangement of the original pixels to be subjected to the interpolation processing, and the pattern matching is performed while shifting the small area of 16 pixels. At this time, it is not necessary to update all information of 16 pixels every time the small area is moved. FIG. 7A shows 16 pixels "EFGHIJKLMNOPQRST" as pixels, and FIG. 7B shows a data register area such as a CPU for processing this. By indicating whether or not each pixel has a dot by 1-bit “1” or “0”, pattern matching is possible if the data width is 16 bits. When the small area is moved by one pixel as shown in FIG. 7A, four pixels “ABCD” are newly included in the small area, and four pixels “QRST” are small. You will be out of range. Then, it is only necessary to shift by 4 bits in the data register area and introduce 4 bits corresponding to 4 pixels of “ABCD” into 4 bits on the LSB side as shown in FIG.
[0102]
In other words, if 16 bits are used as an address for the pattern data arrangement, the matching process is a process of simply specifying the address, and the interpolation pixel information can be obtained as it is.
[0103]
Assuming that the above-described interpolation processing can be performed, in step ST106, an image is read out for each type and interpolation processing is performed. Here, it can be roughly classified into non-meta-command pixels and meta-command pixels. For the former, interpolation processing of the cubic method or the near-list method is executed according to the flow shown in FIG. 20, and for the latter, FIG. An interpolation process by pattern matching is executed according to the flow shown in FIG. FIG. 22 shows a situation in which one line is read for each type in this way. Whether each pixel of the color information virtual drawing surface is a non-metacommand pixel (“N”) based on the attribute information virtual drawing surface Pixels are picked up while determining whether they are meta-command pixels (“C” and “B”). Note that, at this time, pixel information that has been initialized and previously extracted as background pixels is applied.
[0104]
Further, horizontal pixel arrangement alone is not enough to execute the interpolation processing, and information on vertical pixels is also required. Therefore, as shown in FIG. 23, pixels of four lines are actually read, stored in the work area, and the interpolation process is executed. In this example, four lines are used because 16 square pixels of 4 × 4 pixels are used as one processing unit in the above-described cubic method or pattern matching, and can be increased or decreased as needed.
[0105]
By the way, in the interpolation processing by the above-described pattern matching, the dots attached as the meta-command pixels may be deleted. Since this dot has been generated as noise, erasing the meta command pixel restores its original contour. However, the process of filling the dot to be erased with another pixel is not executed. Therefore, if a dot is erased when pixels of different types are adjacent to each other, a gap may be formed there.
[0106]
In such a case, if the area of the adjacent image is enlarged in advance, even if a background pixel occurs at the boundary portion when the interpolation processing is performed on the other image, the pixel of the adjacent image area is generated on the background. So that the gap does not become visible.
[0107]
Therefore, for the non-metacommand pixel, the boundary extension processing is executed in step ST202. This boundary extension process is a process of expanding the boundary at the periphery of a pixel in advance. In FIG. 22, when the non-meta-command pixel is read, the boundary extension processing is executed by copying one pixel outside the pixel adjacent to the background pixel outward.
[0108]
FIG. 24 shows a countermeasure in the case where interpolation processing is performed after the boundary is extended in this way. In FIG. 9A, three of the nine pixels (A to C) contain pixel information, and the remaining six pixels are background pixels. Then, as shown in FIG. 2B, the boundary is extended by copying one pixel adjacent to the boundary outside the boundary. If the boundary is not extended, even if the interpolation processing is performed, the result is only as shown in FIG. 9C. However, if the interpolation processing is performed after the boundary is extended, as shown in FIG. The boundary extends outward. As a result, a base is created for adjacent pixels. In this example, the boundary is extended outward by one pixel, but the boundary may be extended by the required number of pixels corresponding to the number of dots to be erased by pattern matching for the adjacent meta command pixel.
[0109]
In step ST202, boundary extension processing is performed in this sense, and in step ST204, interpolation processing is performed by the cubic method. That is, it is possible to identify and read out the meta-command pixel, and execute the optimal interpolation processing on a natural image or the like.
[0110]
Here, the flow illustrated in FIG. 20 illustrates a process of determining whether or not the image is a natural image by an alternate long and short dash line, and an interpolation process by a near-list method. As described above, in the present embodiment, the bitmap image is determined to be a meta-command pixel, but it may be further determined whether or not the image is a natural image. Therefore, the type of the meta-command pixel is written in the virtual area so as to be known, and whether or not the pixel is a natural image is determined in step ST208. If the pixel is a natural image, the cubic pixel is determined in step ST204 as described above. Alternatively, the interpolation process may be performed using the near-list method in step ST210 if the image is not a natural image.
[0111]
On the other hand, for the meta command pixel, an interpolation process is performed by pattern matching in step ST306. As a result, for a character, dots that have been generated as noise are erased to produce a beautiful line character, and for a business graph, a smooth image without unnatural dots is obtained, and optimal interpolation processing can be performed.
[0112]
In the case of meta command pixels, missing dots may occur during the interpolation process. The countermeasure is to extend the boundary of adjacent non-meta command pixels and overwrite the meta command pixels. . That is, for the non-meta-command pixels, after the interpolation processing is completed, pre-writing is performed in step ST206, and for the meta-command pixels, after the interpolation processing is completed, post-writing is performed in step ST308. In the flowcharts of FIGS. 20 and 21, these steps ST206 and ST308 are represented by dashed lines. This is because these processes actually correspond to the interpolated image superimposing process of step ST108 shown in the flowchart of FIG.
[0113]
The meaning of the pre-writing process of step ST206 and the post-writing process of step ST308 is that the non-metacommand pixel and the metacommand pixel are separated and interpolated in separate work areas, and then combined. That is, the non-meta-command pixel whose boundary has been extended is written first, and the meta-command pixel that has achieved the interpolation processing corresponding to the original meta-command pixel is written later. In this case, if the previously written pixel and the later written pixel do not overlap, the previously written pixel remains, but if it overlaps, the later written pixel remains. Therefore, even if the boundary shape on the side to be written later changes at the boundary where both are adjacent, the background does not appear. Of course, it is not necessary to overwrite the background pixels, and it is natural that the pixels to be overwritten are pixels other than the background pixels.
[0114]
This order is a mode of priority processing in the superimposition processing. Such a write control of the priority processing can be performed in any way in the actual program depending on the technique. Therefore, it is sufficient that the priority processing is substantially maintained, and the same processing may be realized by another method without limitation.
[0115]
After the pixels subjected to the interpolation processing are superimposed, color correction is performed in step ST110 to convert the color coordinates from RGB to CMYK. Perform halftone processing. Then, in step ST114, print data is output to the color printer 17b.
[0116]
Although the above description has been given of the printer driver 12c, the same can be applied to the display driver 12b.
[0117]
As described above, by performing interpolation processing on a pixel generated in response to a metacommand in consideration of the original metacommand, the interpolated image itself is improved, but the boundary region does not match an adjacent pixel. In order to solve the problem, for non-metacommand pixels, the boundary is extended and interpolation processing is performed, and metacommand pixels are prioritized in the overlapping part of both, so most of the extended boundary becomes the base of the adjacent area It is possible to prevent the background pixel from being generated when the boundary shape is changed while being hidden.
[Brief description of the drawings]
FIG. 1 is a diagram corresponding to a claim of an image data interpolation device according to an embodiment of the present invention.
FIG. 2 is a block diagram of specific hardware of the image data interpolation device.
FIG. 3 is a schematic block diagram showing another application example of the image data interpolation device of the present invention.
FIG. 4 is a main flowchart in the image data interpolation device of the present invention.
FIG. 5 is a schematic diagram showing writing on a virtual drawing surface.
FIG. 6 is a schematic diagram showing a comparison between color information and attribute information on a virtual drawing surface.
FIG. 7 is a conceptual diagram of the cubic method.
FIG. 8 is a conceptual diagram of a near-list method.
FIG. 9 is a diagram showing a situation in which data of each grid point is transferred by the near list method.
FIG. 10 is a schematic diagram showing a situation before interpolation in a near-list method.
FIG. 11 is a schematic diagram showing a situation after interpolation in the near-list method.
FIG. 12 is a conceptual diagram of a bilinear method.
FIG. 13 is a diagram showing a change state of an interpolation function.
FIG. 14 is a diagram showing a character image written on a color information virtual drawing surface.
FIG. 15 is a diagram showing a situation in which interpolation information is obtained by pattern matching.
FIG. 16 is a diagram illustrating a process of eliminating noise dots generated in a character by pattern matching.
FIG. 17 is a diagram showing a situation in which interpolation information is obtained by pattern matching when the magnification is different.
FIG. 18 is a diagram showing a situation in which interpolation information including color allocation information is obtained by pattern matching.
FIG. 19 is a diagram showing a specific data processing method of pattern matching.
FIG. 20 is a flowchart of non-metacommand pixel interpolation processing in the image data interpolation device of the present invention.
FIG. 21 is a flowchart of a meta command pixel interpolation process in the image data interpolation device of the present invention.
FIG. 22 is a diagram illustrating a situation in which image data is read for each type and a boundary extension process.
FIG. 23 is a diagram illustrating a situation in which image data is read into a buffer for each type.
FIG. 24 is a diagram illustrating a situation in which a boundary is extended in a boundary extension process.
[Explanation of symbols]
10. Computer system
11a ... Scanner
11b Digital still camera
11c ... Video camera
12 ... Computer body
12a: Operating system
12b ... display driver
12b ... driver
12c: Printer driver
12d… Application
13a: Floppy disk drive
13b ... Hard disk
13c: CD-ROM drive
14a… Modem
15a ... Keyboard
15b… Mouse
17a ... Display
17a1 ... Display
17b ... Color printer
17b1 ... Color printer
17b2 ... Color printer
19a: Network computer
19b… TV monitor

Claims (10)

Virtual drawing means for inputting image data corresponding to the meta-command and other image data and superimposing them in a predetermined order and drawing them in a virtual area while enabling each to be identified;
Non-meta-command pixel interpolation means for expanding the peripheral area when reading pixels corresponding to image data other than the meta-command from the virtual area and performing interpolation processing so as to have a predetermined interpolation magnification,
A meta-command pixel interpolating unit that reads out a pixel corresponding to a meta-command from the virtual area and generates an interpolated pixel so as to correspond to the original meta-command when performing an interpolation process so as to have the interpolation magnification;
Superimposing means for synthesizing the interpolation result of the non-metacommand pixel interpolating means and the interpolation result of the metacommand pixel interpolating means and giving priority to the interpolation result of the metacommand pixel interpolating means in an overlapping portion thereof. Characteristic image data interpolation device. 2. The image data interpolating apparatus according to claim 1, wherein said non-metacommand pixel interpolating means uses information on pixels in a peripheral area as information on pixels outside the area. . 3. The image data interpolating device according to claim 1, wherein the meta command pixel interpolating means interpolates a meta command representing a character and generates a pixel of noise when generating a pixel based on the meta command. An image data interpolation apparatus characterized in that pixel interpolation is performed by deleting the image data. The image data interpolation device according to any one of claims 1 to 3, wherein the meta-command pixel interpolation means reads pixels of a plurality of lines and performs an interpolation process when reading the pixels from the virtual area. Characteristic image data interpolation device. 5. The image data interpolating apparatus according to claim 4, wherein the meta command pixel interpolating means interpolates the pattern data corresponding to the presence or absence of the pixel information in the area of the predetermined size and the predetermined interpolation magnification corresponding to each pattern data. Pixel information is provided, and pixels in the corresponding area are read out from the virtual area as comparison data, and are subjected to interpolation processing based on interpolation pixel information prepared corresponding to the matched pattern data by matching the same pattern data. An image data interpolation device characterized by the above-mentioned. 6. The image data interpolating apparatus according to claim 5, wherein the meta command pixel interpolating means is a rectangular area having a number of pixels corresponding to a data width that can be simultaneously processed, and the target rectangular area is moved. 3. The image data interpolation apparatus according to claim 1, wherein a new pixel column is incorporated in said comparison data by a first-in first-out process to continue matching with pattern data. In the image data interpolation device according to any one of claims 5 and 6, in the meta command pixel interpolation means, the interpolation pixel information corresponding to the pattern data is the color allocation information of each pixel in the comparison data. An image data interpolation apparatus characterized by including: 8. The image data interpolating apparatus according to claim 1, wherein the superimposing means writes the interpolation result of the non-meta-command pixel interpolating means in a predetermined area first, and then outputs the meta-command pixel. An image data interpolation device for overwriting pixels other than the background pixel in the interpolation result of the interpolation means. An image data interpolation method for increasing the number of constituent pixels based on image data to be rendered by expressing an image with pixels in a dot matrix,
A step of inputting image data corresponding to the meta command and other image data, and superimposing and drawing in a predetermined order so that each can be identified;
When reading out the pixels corresponding to the image data other than the meta-command from the virtual area, expanding the peripheral area and performing an interpolation process so as to have a predetermined interpolation magnification,
A step of generating an interpolated pixel so as to correspond to the original metacommand when reading a pixel corresponding to a metacommand from the virtual area and performing an interpolation process so as to have the interpolation magnification;
A step of combining the interpolation results based on the two steps and giving priority to the interpolation result corresponding to the meta command in an overlapping portion thereof, and combining them. A medium that records an interpolation processing program that executes an interpolation processing by a computer so as to increase the number of constituent pixels based on image data that is drawn by expressing an image with pixels in a dot matrix shape,
Inputting image data and other image data corresponding to the meta command, and superimposing and drawing in a predetermined order so that each can be identified;
When reading pixels corresponding to image data other than the meta command from the virtual area, expanding the peripheral area and performing an interpolation process so as to have a predetermined interpolation magnification;
A step of generating an interpolated pixel so as to correspond to the original metacommand when reading a pixel corresponding to a metacommand from the virtual area and performing an interpolation process so as to have the interpolation magnification;
A step of combining the interpolation results based on the two processes and giving priority to the interpolation result corresponding to the meta command in an overlapping portion thereof, and combining the results.

Images