JP4195947B2 - Image forming apparatus - Google Patents

Description

【００１３】
なお、１から４までで用いられるサンプルウインドウ内において、被処理対象画素対象エッジ１２が左でなく右、上、下のときは、論理演算、重み付け演算の分布を被処理対象画素対象エッジ１２に対して同じ位置になる。すなわち、論理演算、重み付け演算の分布をそれぞれ回転させたイメージになる。また、論理演算と重み付け演算を適用した後の重み付けデータ値の総和を左、右、上、下においてＬ（（数１）参照）、Ｒ、Ｕ、Ｄと定義する。
【００１４】
次に、処理制御手段５の動作について図１６、図１７を用いて説明する。図１６に主走査方向の変換テーブル２０、２１を示し、図１７に副走査方向の変換テーブル２２を示す。なお、論理演算と重み付け演算を適用した後の重み付けデータ値の総和Ｌ、Ｒ、Ｕ、Ｄのしきい値を２段階設ける。そして、総和Ｌ、Ｒ、Ｕ、Ｄが低い方のしきい値を越えたときに通常処理フラグｌ、ｒ、ｕ、ｄを「１」とし、総和Ｌ、Ｒ、Ｕ、Ｄが高い方のしきい値を越えたときに強調処理フラグｌｋ、ｒｋ、ｋを「１」とする。ただし、副走査方向の強調処理フラグｋは総和Ｕ、Ｄのどちらかが高い方のしきい値を越えたときに「１」とするものとする。また、被処理対象画素が黒のとき処理フラグＢを「１」とする。その上で、各方向の変換テーブル２０、２１、２２に記載された処理をする。なお、各処理フラグが変換テーブル２０〜２２に記載されている組合わせ以外の組合わせをとる場合、すなわち、主走査方向の処理フラグと副走査方向の処理フラグが同時に「１」になった場合、各走査方向においてなされる処理の論理和をとった形になる。その際、黒い部分を「１」、白い部分を「０」とおいて考える。なお、図１６の斜線で表した処理のイメージは、こういう処理フラグの組合わせ自体が存在しない場合を示している。
【００１５】
図１８に、以上のスムージング処理を施した結果を示す。図１８（ａ）は主走査方向の処理動作を示すための原画像を示し、図１８（ｂ）は主走査方向の処理動作を示し、図１８（ｃ）は副走査方向の処理動作を示すための原画像を示し、図１８（ｄ）は副走査方向の実際の処理動作を示し、図１８（ｅ）は副走査方向の処理動作後のイメージ２３を示す。図１８で、特に副走査方向のスムージングについては、プリンタの解像度が処理前のデータの解像度と変わらないため、実印字時のドットの大きさすなわち印字濃度を変化させることによって、副走査方向の処理動作後のイメージ（以下、「処理動作イメージ」という）２３を等価的に実現させていた。
【００１６】
【発明が解決しようとする課題】
しかしながら、上記従来の画像形成装置では、上述したように、主走査方向においては、転送された処理前のデータの解像度よりもプリンタの印字可能な解像度の方が高いために、実際に印字された画像と処理動作イメージとは一致していたが、副走査方向においては、転送された元のデータの解像度とプリンタの印字可能な解像度とが同じであるため、処理をかけるドットの印字濃度を調整することにより実際の印字を行っており、実際の印字された画像と処理動作イメージとが異なるという問題点を有していた。
【００１７】
この画像形成装置では、副走査方向において転送された処理前のデータの解像度よりもプリンタの印字可能な解像度の方が高い場合には解像度向上処理を行うことができることが要望されていた。
【００１８】
本発明は、転送された処理前のデータの解像度よりもプリンタの印字可能な解像度の方が高い場合に解像度向上処理を行うことができる画像形成装置を提供することを目的とする。
【００１９】
【課題を解決するための手段】
この課題を解決するために本発明による画像形成装置は、解像度向上処理前の画像の被処理対象画素を中心に据えてサンプルウインドウを設定するサンプルウインドウ設定手段と、前記サンプルウインドウ内においてエッジを検出するエッジ検出手段と、前記サンプルウインドウ内において所定の箇所に定められた論理演算を施して前記検出されたエッジが重みを乗算するエッジか否かを判定する論理演算手段と、前記論理演算手段において重みを乗算するエッジと判定されたエッジに対して前記サンプルウインドウ内に分布する重みを乗算して前記サンプルウインドウ内について重み付けデータ値の総和を算出する重み付け演算手段と、プリンタの印字可能な最小ドットの組み合わせから構成されているパターンを保持するテーブルと、副走査方向で前記解像度向上処理前の画像データの解像度をプリンタの印字可能な解像度が上回る場合に、前記重み付け演算手段で得られた前記重み付けデータ値の総和と周囲のエッジの状態とに応じて、前記テーブルが保持するパターンの中から、前記解像度向上処理前の画像データの１ドットの処理を選択することにより、前記選択された処理の内容を印字濃度と印字位置を変化させることなく出力する処理制御手段とを有するように構成したものである。
【００２０】
これにより、転送された処理前のデータの解像度よりもプリンタの印字可能な解像度の方が高い場合に解像度向上処理を行うことができる画像形成装置が得られる。
【００２１】
【発明の実施の形態】
本発明の請求項１に記載の発明は、解像度向上処理前の画像の被処理対象画素を中心に据えてサンプルウインドウを設定するサンプルウインドウ設定手段と、前記サンプルウインドウ内においてエッジを検出するエッジ検出手段と、前記サンプルウインドウ内において所定の箇所に定められた論理演算を施して前記検出されたエッジが重みを乗算するエッジか否かを判定する論理演算手段と、前記論理演算手段において重みを乗算するエッジと判定されたエッジに対して前記サンプルウインドウ内に分布する重みを乗算して前記サンプルウインドウ内について重み付けデータ値の総和を算出する重み付け演算手段と、プリンタの印字可能な最小ドットの組み合わせから構成されているパターンを保持するテーブルと、副走査方向で前記解像度向上処理前の画像データの解像度をプリンタの印字可能な解像度が上回る場合に、前記重み付け演算手段で得られた前記重み付けデータ値の総和と周囲のエッジの状態とに応じて、前記テーブルが保持するパターンの中から、前記解像度向上処理前の画像データの１ドットの処理を選択することにより、前記選択された処理の内容を印字濃度と印字位置を変化させることなく出力する処理制御手段とを有することとしたものであり、転送された処理前のデータの解像度よりもプリンタの印字可能な解像度の方が高い場合には解像度向上処理が施されるという作用を有する。
【００２２】
以下、本発明の実施の形態について、図１〜図９を用いて説明する。
（実施の形態１）
本発明の実施の形態１による画像形成装置の構成は従来の画像形成装置と同様に図９に示す構成である。本実施の形態が従来の画像形成装置と異なる点は処理制御手段５における処理である。本実施の形態による処理制御手段５における処理では、主走査方向の処理を行った後、主走査方向の処理を施していない部分に関してのみ副走査方向の処理を施しているので、従来の処理制御手段におけるような論理和演算が不要となる。
【００２３】
以上のように構成された画像形成装置について、論理演算手段４および処理制御手段５の動作を図１〜図８を用いて説明する。図１（ａ）、図１（ｂ）、図２（ａ）、図２（ｂ）、図３（ａ）、図３（ｂ）、図３（ｃ）、図４は左エッジにおける論理演算処理を示す処理図である。図１〜図４において斜線で示す部分は被処理対象画素３０である。なお、図１〜図４において、白丸○はエッジが存在しないときに「１」とする部分であり、黒丸●はエッジが存在しているときに「１」とする部分、●→●は論理積演算、●←→●は論理和演算を示す。
【００２４】
図１〜図４と（数２）との対応関係について記す。なお、図１〜図４は左エッジ判定を例にとった図であり、右エッジ、上エッジ、下エッジの判定についてはそれぞれ回転して使用できるような対称関係にある。
【００２５】
【数２】

【００２６】
（数２）で用いられているエッジデータの座標表現については、図１５（ａ）における主走査方向エッジ用座標表示を表す座標表現に準拠し、左エッジであることを示すために一番左にＬをつけることにする。例を挙げると、被処理対象画素３０の左エッジのエッジ座標表現はＬｂ４である。
【００２７】
また、図１はａ列のエッジにおける論理演算処理を示し、図２はｂ列のエッジにおける論理演算処理を示し、図３はｃ列のエッジにおける論理演算処理を示し、図４はｄ列のエッジにおける論理演算処理を示している。
【００２８】
図１（ａ）は（数２）における第１項目すなわちＡ１の部分を示し、図１（ｂ）は（数２）における第２項目と第３項目すなわちＡ２＋Ａ３の部分を示している。
【００２９】
図２（ａ）は（数２）における第４項目すなわちＡ４の部分を示し、図２（ｂ）は（数２）における第６項目すなわちＡ６の部分を示している。図３（ａ）は（数２）における第９項目すなわちＡ９の部分を示し、図３（ｂ）は（数２）における第１０項目すなわちＡ１０の部分を示し、図３（ｃ）は（数２）における第１１項目すなわちＡ１１の部分を示している。図４は（数２）における第１２項目と第１３項目すなわちＡ１２＋Ａ１３の部分を示している。
【００３０】
図５は、被処理対象画素３０の左エッジを例にとった重み付け分布を示す重み付け分布図である。この重み付け分布により重み付け演算を行う。すなわち、重み付け演算手段４は、サンプルウインドウ内において重み付けデータ値の総和をとる。
【００３１】
被処理対象画素３０の左エッジに対して論理演算と重み付け演算を適用した後の重み付けデータ値の総和を（数２）のＬで表す（Ｌは左エッジを対象としたときを示す）。
【００３２】
このように一度に重み付けデータ値の総和Ｌを算出することができる。
次に、処理制御手段５の動作について図６、図７を用いて説明する。図６は主走査方向の変換テーブル３１を示す変換テーブル図、図７は副走査方向の変換テーブル３２を示す変換テーブル図である。なお、上述したように、本実施の形態による処理制御手段５における処理では、主走査方向での処理を行った後、主走査方向の処理を施していない部分にのみ副走査方向での処理を施しているので、記載した変換テーブル以外の変換処理は存在しない。また、副走査方向の被処理対象画素対象エッジの箇所が判定され、かつ、被処理対象画素の主走査方向の左エッジ、右エッジのうちどちらかが存在した場合にのみ副走査方向の変換テーブル３２で示す処理を行う。なお、変換テーブル３２の中の１行目と２行目において、左、右のエッジが存在したときは「１」、存在しないときは「０」としている。
【００３３】
図８に、以上のスムージング処理を施した結果を示す。図８（ａ）、（ｂ）はスムージング処理を施した結果としての主走査方向動作図、図８（ｃ）、（ｄ）はスムージング処理を施した結果としての副走査方向動作図である。図８（ａ）は主走査方向の処理動作を示すための原画像を示し、図８（ｂ）は主走査方向の処理動作を示し、図８（ｃ）は副走査方向の処理動作を示すための原画像を示し、図８（ｄ）は副走査方向の処理動作後の状態を示す。図８（ｃ）、（ｄ）に記載された副走査方向での処理は、ドットの濃度を調整することによって疑似的にスムージングを実現しているような従来例とは異なり、ドットの濃度は何ら調整されないので、実際の施される処理動作後の画像と処理動作イメージとは一致する。
【００３４】
以上のように本実施の形態によれば、処理制御手段５は、副走査方向で解像度向上処理前の画像データの解像度をプリンタの印字可能な解像度が上回る場合に、重み付け演算手段４で得られた重み付けデータ値の総和と周囲のエッジの状態とに応じて、プリンタの印字可能な最小ドットの組み合わせから構成されている解像度向上処理前の画像データの最小ドットと同じ大きさの複数のパターンの中から、解像度向上処理前の画像データの１ドットの処理を選択することにより、選択された処理の内容を印字濃度と印字位置を変化させることなく出力するようにしたので、転送された処理前のデータの解像度よりもプリンタの印字可能な解像度の方が高い場合に解像度向上処理を行うことができる。
【００３５】
【発明の効果】
以上のように本発明の画像形成装置によれば、処理制御手段においては選択された処理の内容を印字濃度と印字位置を変化させることなく出力するようにしたので、転送された処理前のデータの解像度よりもプリンタの印字可能な解像度の方が高い場合に解像度向上処理を行うことができるという有利な効果が得られる。
【図面の簡単な説明】
【図１】（ａ）左エッジにおける論理演算処理を示す処理図
（ｂ）左エッジにおける論理演算処理を示す処理図
【図２】（ａ）左エッジにおける論理演算処理を示す処理図
（ｂ）左エッジにおける論理演算処理を示す処理図
【図３】（ａ）左エッジにおける論理演算処理を示す処理図
（ｂ）左エッジにおける論理演算処理を示す処理図
（ｃ）左エッジにおける論理演算処理を示す処理図
【図４】左エッジにおける論理演算処理を示す処理図
【図５】被処理対象画素の左エッジを例にとった重み付け分布を示す重み付け分布図
【図６】主走査方向の変換テーブルを示す変換テーブル図
【図７】副走査方向の変換テーブルを示す変換テーブル図
【図８】（ａ）スムージング処理を施した結果としての主走査方向動作図
（ｂ）スムージング処理を施した結果としての主走査方向動作図
（ｃ）スムージング処理を施した結果としての副走査方向動作図
（ｄ）スムージング処理を施した結果としての副走査方向動作図
【図９】一般的な画像形成装置を示すブロック図
【図１０】（ａ）サンプルウインドウを示すサンプルウインドウ図
（ｂ）サンプルウインドウの動きを示すサンプルウインドウ動き図
【図１１】（ａ）左エッジを例としたエッジ検出方法を説明するためのエッジ検出方法説明図
（ｂ）左エッジを例としたエッジ検出方法を説明するためのエッジ検出方法説明図
【図１２】（ａ）論理演算における各種エッジを示すエッジ図
（ｂ）論理演算における各種エッジを示すエッジ図
【図１３】重み付け分布を示す重み付け分布図
【図１４】（ａ）不具合を説明するためのパターンの例を示すパターン図
（ｂ）不具合を説明するためのパターンの例を示すパターン図
（ｃ）不具合を説明するためのパターンの例を示すパターン図
（ｄ）不具合を説明するためのパターンの例を示すパターン図
（ｅ）不具合を説明するためのパターンの例を示すパターン図
【図１５】（ａ）主走査方向エッジ用座標表示を示す座標表示図
（ｂ）副走査方向エッジ用座標表示を示す座標表示図
【図１６】（ａ）処理制御手段を用いて得られた主走査方向の変換テーブルを示す変換テーブル図
（ｂ）処理制御手段を用いて得られた主走査方向の変換テーブルを示す変換テーブル図
【図１７】処理制御手段を用いて得られた副走査方向の変換テーブルを示す変換テーブル図
【図１８】（ａ）従来のスムージング処理を施した結果としての主走査方向動作図
（ｂ）従来のスムージング処理を施した結果としての主走査方向動作図
（ｃ）従来のスムージング処理を施した結果としての副走査方向動作図
（ｄ）従来のスムージング処理を施した結果としての副走査方向動作図
（ｅ）従来のスムージング処理を施した結果としての副走査方向動作図
【符号の説明】
１ サンプルウインドウ設定手段
２ エッジ検出手段
３ 論理演算手段
４ 重み付け演算手段
５ 処理制御手段
３０ 被処理対象画素
３１ 主走査方向の変換テーブル
３２ 副走査方向の変換テーブル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a laser printer that forms image data constituting an orthogonal matrix in a row direction and a column direction by horizontal and vertical scanning.
[0002]
[Prior art]
In recent years, the printable resolution of printers has increased, but in order to save memory capacity and transfer time when transferring data, the outer shape is smoother than the resolution of the transferred data (and therefore the resolution itself is also increased). It is demanded that an external shape) can be obtained. Therefore, various smoothing techniques have been devised. A conventional smoothing technique is disclosed in, for example, Japanese Patent Laid-Open No. 4-323959. This is to detect the edge by the edge detection means, weight the edge by the weighting means, perform the logical operation according to the weighting by the logical operation means, select the dot size according to the calculation result by the compensation control means, This is a technique for correcting image dot data according to the size of the dot selected by the correction control means in the signal generation means. This correction technique is used when the resolution of the data before the resolution enhancement processing and the resolution of the printer match in the sub-scanning direction. Smoothing is performed by changing the dot size, that is, the print density. The processing is performed.
[0003]
FIG. 9 is a block diagram showing a general image forming apparatus. In FIG. 9, a sample window setting means 1 sets a sample window centering on a pixel to be processed of an image before resolution enhancement processing, an edge detection means 2 detects an edge in the sample window, and a logical operation means 3 Determines whether an edge detected by performing a logical operation defined at a predetermined location in the sample window is an edge to be multiplied by the weight, and the weighting operation means 4 The determined edge is multiplied by the weight distributed in the sample window to calculate the sum of weighted data values to be described later in the sample window. The processing control means 5 sets an edge flag to be processed when the sum exceeds a certain threshold value, and performs processing described later. From the edge detection means 2 to the weighting calculation means 4, the same processing is performed on one edge to be processed for each edge in the main scanning direction and the sub-scanning direction, that is, left, right, up and down.
[0004]
The processing operation of the conventional image forming apparatus configured as described above will be described with reference to FIGS. FIG. 10A is a sample window diagram showing the sample window, FIG. 10B is a sample window motion diagram showing the movement of the sample window, and FIG. 10A is a processing target of the image 8 before the resolution improvement processing. A case where the sample window 7 is set centering on the pixel 6 is shown. 8a is a minimum unit pixel before the resolution improvement process, and FIG. 10B shows the processing target pixel 6 of the image 8 before the resolution improvement process. The movement 9 of the sample window 7 taken at the center is shown. 11A and 11B are explanatory diagrams of an edge detection method for explaining an edge detection method using the left edge as an example. FIG. 11A shows a pixel 10 to be processed in the sample window 10a. Reference numeral 10b denotes a minimum unit pixel before resolution improvement processing, and FIG. 11B shows an edge data distribution 11. FIGS. 12A and 12B are edge diagrams showing various edges in the logical operation. FIG. 12 shows the processing target pixel target edge 12 (white circle), the logical operation use edge 13 (white square), and the logical operation target edge. 14 (black square), logical operation edge states 15 and 16 are shown. FIG. 13 is a weight distribution diagram showing the weight distribution, and shows the weight distribution 17 for the processing target pixel target edge 12. FIGS. 14A to 14E are pattern diagrams showing patterns for explaining problems. 15A is a coordinate display diagram showing coordinate display for main scanning direction edges, FIG. 15B is a coordinate display diagram showing coordinate display for edge in the sub scanning direction, and FIG. 15A is an edge in the main scanning direction. FIG. 15B shows the processing target pixel 10 in the sub-scanning direction edge coordinate display, and reference numerals 18a and 19a denote minimum unit pixels before the resolution improvement processing. 16A and 16B are conversion table diagrams showing a conversion table in the main scanning direction obtained by using the processing control means 5, and FIG. 16A shows a conversion table 20 in the main scanning direction. FIG. 16B shows a conversion table 21 in the main scanning direction. FIGS. 16A and 16B differ in that data B is all “0” or all “1”. FIG. 17 is a conversion table diagram showing a conversion table in the sub-scanning direction obtained using the processing control means 5, and FIG. 17 shows a conversion table 22 in the sub-scanning direction. 18A and 18B are main scanning direction operation diagrams as a result of performing the conventional smoothing process, and FIGS. 18C to 18E are sub-scanning direction operations as a result of performing the conventional smoothing process. FIG. 18E shows an image 23 after the operation in the sub-scanning direction.
[0005]
First, the operation of the sample window setting means 1 will be described with reference to FIG. As shown in FIG. 10A, a sample window is set with the processing target pixel 6 as the center. All the pixels of the image 8 before the resolution improving process are set to be processed pixels 6. The movement 9 of the sample window 7 for that purpose is shown in FIG. When the processing for the first line is completed, the sample window 7 is moved to the second and third lines next time. However, in the following description, the fixed sample window 7 will be described.
[0006]
Next, the operation of the edge detection means 2 will be described with reference to FIG. As shown in FIG. 11A, when the pixel on the left side of the pixel 10 to be processed is different in color from the pixel 10 to be processed, it is determined whether there is the same pattern as the color difference in the sample window. Search in. As shown in FIG. 11B, a flag is set, and a flag in a portion where the same pattern exists is set to “1”, and a flag in a portion where the same pattern does not exist is set to “0”. Similar processing is performed on the right edge and the upper and lower edges of the same pixel 10 to be processed. 11 shows the case where the pixel 10 to be processed is black and the pixel to the left is white, but the edge shown in FIG. 11B is also the case where the pixel 10 to be processed is white and the pixel to the left is black. It is exactly the same as the data distribution 11.
[0007]
Next, the operation of the logical operation means 3 will be described with reference to FIG. A white circle indicates a processing target pixel target edge (here, the left edge) 12. Only when the logical operation use edge 13 indicated by the white square is present, the black square logical operation target edge 14 indicated by the arrow from the logical operation use edge 13 is regarded as an edge that can be used for the weighting operation. The positional relationship is as shown in FIGS. 12 (a) and 12 (b). Note that this positional relationship becomes a target when the processing target pixel target edge 12 is taken from left to right and up and down. The values of edge data other than the logical operation target edge 14 are exactly the same as the values of edge data shown in FIG. That is, the logical operation means 3 serves only as an auxiliary function of the weighting operation, and is for avoiding problems caused by simply performing the weighting operation processing.
[0008]
In order to show an example of this defect, examples of patterns for explaining the problem are shown in FIGS. FIG. 14C shows the result of processing the target pixel 17a and the target pixel 18b shown in FIGS. 14A and 14B using this algorithm in this pattern. As a result, a shape is formed between the target pixel 17a and the target pixel 18b, which causes a problem. The reason is as described next. The result obtained by multiplying the left edge of the target pixel 1 through the weighting calculation means 4, that is, the value of the edge data corresponding to the weight in FIG. 13 and taking the total in the sample window is 8. . Therefore, the edge is corrected because the threshold value is 8 or more which is designated in advance.
[0009]
Therefore, the logical operation means 3 is used to determine whether or not to cancel the weight corresponding to the position of the logical operation target edge 14. The determination is made based on the surrounding edge state, that is, the distribution of the logic operation use edges 13. In this example, the logical operation means described in FIG. 12B is applied. As shown in FIG. 14D, since Lc3 does not exist, the weight corresponding to La6, that is, in FIG. 14D is not added. Therefore, the sum of the left edge of the target pixel 1 in the sample window is again obtained by using the weighting operation means 4 and the logic operation means 3 to be 7. Since this result does not exceed the threshold value 8, the edge is not corrected, and hence the problem can be eliminated as shown in FIG.
[0010]
Next, the operation of the weight calculation means 4 will be described with reference to FIG. The weighting positional relationship is as shown in the weighting distribution 17, and takes the product of the edge data value after applying the logical operation in the logical operation means 3 and the weight corresponding to the location (hereinafter referred to as "weighted data value"), The sum of the weighted data values is taken in the sample window 7.
[0011]
FIG. 15 shows an example of the coordinate expression used in the sample window used from 1 to 4. For example, when the processing target pixel target edge 12 is a left and right edge, the main scanning direction edge coordinate display 18 is used, and is represented as Lb4 and Rc4, respectively. When the processing target pixel target edge 12 is an upper and lower edge, the sub-scanning direction edge coordinate display 19 is used, and is represented as UB4 and DC4, respectively. In general, the sum of the weighted data values after applying the logical operation and the weighting operation is represented by L in (Equation 1) (L indicates when the left edge is targeted).
[0012]
[Expression 1]

[0013]
In the sample window used in 1 to 4, when the processing target pixel target edge 12 is not on the left but on the right, top, and bottom, the distribution of the logical operation and the weighting calculation is set to the processing target pixel target edge 12. For the same position. That is, the image is obtained by rotating the distribution of the logical operation and the weighting operation. Further, the sum of the weighted data values after applying the logical operation and the weighting operation is defined as L (see (Equation 1)), R, U, and D on the left, right, top, and bottom.
[0014]
Next, the operation of the processing control means 5 will be described with reference to FIGS. FIG. 16 shows conversion tables 20 and 21 in the main scanning direction, and FIG. 17 shows a conversion table 22 in the sub scanning direction. It should be noted that two threshold values are provided for the sum L, R, U, and D of the weighted data values after applying the logical operation and the weighting operation. Then, when the sum L, R, U, D exceeds the lower threshold, the normal processing flags l, r, u, d are set to “1”, and the sum L, R, U, D is higher. When the threshold value is exceeded, the emphasis processing flags lk, rk, k are set to “1”. However, the emphasis processing flag k in the sub-scanning direction is set to “1” when either the sum U or D exceeds the higher threshold value. Further, when the pixel to be processed is black, the processing flag B is set to “1”. Then, the processing described in the conversion tables 20, 21, and 22 for each direction is performed. When each processing flag takes a combination other than the combinations described in the conversion tables 20 to 22, that is, when the processing flag in the main scanning direction and the processing flag in the sub scanning direction are simultaneously “1”. The logical sum of the processing performed in each scanning direction is obtained. At that time, the black part is considered as “1” and the white part as “0”. Note that the image of processing represented by hatching in FIG. 16 shows a case where such a combination of processing flags does not exist.
[0015]
FIG. 18 shows the result of the above smoothing process. 18A shows an original image for showing the processing operation in the main scanning direction, FIG. 18B shows the processing operation in the main scanning direction, and FIG. 18C shows the processing operation in the sub scanning direction. 18D shows an actual processing operation in the sub-scanning direction, and FIG. 18E shows an image 23 after the processing operation in the sub-scanning direction. In FIG. 18, especially for smoothing in the sub-scanning direction, since the resolution of the printer does not change from the resolution of the data before processing, the processing in the sub-scanning direction is performed by changing the dot size at the time of actual printing, that is, the printing density. An image after operation (hereinafter referred to as “processing operation image”) 23 is equivalently realized.
[0016]
[Problems to be solved by the invention]
However, as described above, in the conventional image forming apparatus, since the resolution that can be printed by the printer is higher than the resolution of the transferred data before processing in the main scanning direction, the image is actually printed. The image and the processing operation image matched, but in the sub-scanning direction, the resolution of the transferred original data and the printable resolution of the printer are the same, so the print density of the dots to be processed is adjusted As a result, actual printing is performed, and the actual printed image and the processing operation image are different.
[0017]
This image forming apparatus is required to be able to perform resolution improvement processing when the resolution that can be printed by the printer is higher than the resolution of data before processing transferred in the sub-scanning direction.
[0018]
An object of the present invention is to provide an image forming apparatus capable of performing resolution improvement processing when the resolution of a printer that can be printed is higher than the resolution of transferred data before processing.
[0019]
[Means for Solving the Problems]
In order to solve this problem, an image forming apparatus according to the present invention includes sample window setting means for setting a sample window centering on a pixel to be processed of an image before resolution enhancement processing, and detecting an edge in the sample window. An edge detecting means that performs a logical operation determined at a predetermined location in the sample window and determines whether or not the detected edge is an edge that is multiplied by a weight; and Weighting calculation means for calculating the sum of weighted data values in the sample window by multiplying the edge determined as the edge to be multiplied by the weight distributed in the sample window, and the minimum printable dot of the printer a table for holding a pattern of a combination of being configured, sub When in 査 direction the resolution of the resolution enhancement processing prior to image data printable resolution of the printer above, according to the state of total and around the edges of the weighting data value obtained by the weighting calculation means, Processing for outputting the contents of the selected processing without changing the print density and the printing position by selecting the processing of one dot of the image data before the resolution improvement processing from the patterns held in the table And a control means.
[0020]
As a result, an image forming apparatus capable of performing the resolution improvement process when the resolution that can be printed by the printer is higher than the resolution of the transferred data before the processing is obtained.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, sample window setting means for setting a sample window centering on a pixel to be processed of an image before resolution enhancement processing, and edge detection for detecting an edge in the sample window Means, logical operation means for determining whether or not the detected edge is an edge for multiplying a weight by performing a logical operation defined at a predetermined location in the sample window, and multiplying the weight in the logical operation means A combination of weighting calculation means for calculating a sum of weighted data values in the sample window by multiplying an edge determined to be an edge to be distributed in the sample window, and a minimum printable dot of the printer a table for holding a pattern that is configured, the resolution sub-scanning direction When exceeding the resolution of the image data before the above processing is printable resolution of the printer, according to the state of total and around the edges of the weighting data value obtained by the weighting calculation means, the table holds Processing control means for outputting the content of the selected process without changing the print density and the print position by selecting one dot process of the image data before the resolution improving process from the pattern. In the case where the resolution that can be printed by the printer is higher than the resolution of the transferred data before processing, the resolution improving process is performed.
[0022]
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
(Embodiment 1)
The configuration of the image forming apparatus according to the first embodiment of the present invention is the configuration shown in FIG. 9 as in the conventional image forming apparatus. The difference between the present embodiment and the conventional image forming apparatus is the processing in the processing control unit 5. In the processing in the processing control means 5 according to the present embodiment, processing in the main scanning direction is performed, and then processing in the sub-scanning direction is performed only for the portions that are not subjected to processing in the main scanning direction. The logical sum operation as in the means becomes unnecessary.
[0023]
With respect to the image forming apparatus configured as described above, the operations of the logical operation means 4 and the processing control means 5 will be described with reference to FIGS. 1 (a), FIG. 1 (b), FIG. 2 (a), FIG. 2 (b), FIG. 3 (a), FIG. 3 (b), FIG. 3 (c), and FIG. It is a processing figure showing processing. In FIG. 1 to FIG. 4, the hatched portion is the processing target pixel 30. 1 to 4, a white circle ○ is a portion that is set to “1” when no edge is present, a black circle ● is a portion that is set to “1” when an edge is present, and ● → ● is a logical value. Product operation, ● ← → ● indicates logical OR operation.
[0024]
The correspondence between FIGS. 1 to 4 and (Equation 2) will be described. 1 to 4 are diagrams using left edge determination as an example, and the determination of the right edge, the upper edge, and the lower edge is in a symmetrical relationship that can be rotated and used.
[0025]
[Expression 2]

[0026]
The coordinate expression of the edge data used in (Equation 2) is based on the coordinate expression representing the coordinate display for the main scanning direction edge in FIG. 15A, and is leftmost to indicate that it is the left edge. Let's add L to. For example, the edge coordinate representation of the left edge of the pixel 30 to be processed is Lb4.
[0027]
1 shows the logical operation processing at the edge of the column a, FIG. 2 shows the logical operation processing at the edge of the column b, FIG. 3 shows the logical operation processing at the edge of the column c, and FIG. Fig. 4 shows logical operation processing at an edge.
[0028]
FIG. 1 (a) shows the first item in (Equation 2), that is, the portion of A1, and FIG. 1 (b) shows the second item in (Equation 2) and the third item, that is, the portion of A2 + A3.
[0029]
2A shows the fourth item in (Equation 2), that is, the portion of A4, and FIG. 2B shows the sixth item in (Equation 2), that is, the portion of A6. 3 (a) shows the ninth item in (Equation 2), that is, the portion of A9, FIG. 3 (b) shows the tenth item in (Equation 2), that is, the portion of A10, and FIG. The eleventh item in 2), that is, the portion of A11 is shown. FIG. 4 shows the twelfth item and the thirteenth item, that is, the portion of A12 + A13 in (Equation 2).
[0030]
FIG. 5 is a weighting distribution diagram showing a weighting distribution taking the left edge of the pixel 30 to be processed as an example. A weighting calculation is performed using this weighting distribution. That is, the weighting calculation means 4 takes the sum of the weighted data values within the sample window.
[0031]
The sum of weighted data values after applying logical operation and weighting operation to the left edge of the pixel 30 to be processed is represented by L in (Expression 2) (L indicates when the left edge is targeted).
[0032]
In this way, the sum L of the weighted data values can be calculated at a time.
Next, the operation of the processing control means 5 will be described with reference to FIGS. FIG. 6 is a conversion table showing the conversion table 31 in the main scanning direction, and FIG. 7 is a conversion table showing the conversion table 32 in the sub-scanning direction. As described above, in the processing in the processing control unit 5 according to the present embodiment, after performing processing in the main scanning direction, processing in the sub-scanning direction is performed only on a portion not subjected to processing in the main scanning direction. Therefore, there is no conversion processing other than the conversion table described. Further, the conversion table in the sub-scanning direction is determined only when the location of the target pixel target edge in the sub-scanning direction is determined and either the left edge or the right edge in the main scanning direction of the processing target pixel exists. The process indicated by 32 is performed. In the first and second lines in the conversion table 32, “1” is set when left and right edges are present, and “0” is set when there are no left and right edges.
[0033]
FIG. 8 shows the result of the above smoothing process. 8A and 8B are operation diagrams in the main scanning direction as a result of performing the smoothing process, and FIGS. 8C and 8D are operation diagrams in the sub-scanning direction as a result of performing the smoothing process. FIG. 8A shows an original image for showing the processing operation in the main scanning direction, FIG. 8B shows the processing operation in the main scanning direction, and FIG. 8C shows the processing operation in the sub scanning direction. FIG. 8D shows a state after the processing operation in the sub-scanning direction. The processing in the sub-scanning direction described in FIGS. 8C and 8D differs from the conventional example in which the smoothing is realized in a pseudo manner by adjusting the dot density. Since no adjustment is made, the image after the actual processing operation and the processing operation image match.
[0034]
As described above, according to the present embodiment, the processing control unit 5 is obtained by the weighting calculation unit 4 when the resolution that can be printed by the printer exceeds the resolution of the image data before the resolution improvement processing in the sub-scanning direction. Depending on the sum of the weighted data values and the state of surrounding edges, multiple patterns of the same size as the minimum dot of the image data before resolution improvement processing, which is composed of the combination of the minimum printable dots of the printer By selecting the 1-dot processing of the image data before the resolution enhancement processing, the content of the selected processing is output without changing the print density and the print position. When the resolution that can be printed by the printer is higher than the resolution of the data, the resolution improvement processing can be performed.
[0035]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, the content of the selected process is output without changing the print density and the print position in the process control unit. An advantageous effect is obtained in that the resolution improvement processing can be performed when the resolution that can be printed by the printer is higher than the resolution.
[Brief description of the drawings]
1A is a processing diagram showing logical operation processing at the left edge; FIG. 1B is a processing diagram showing logical operation processing at the left edge; FIG. 2A is a processing diagram showing logical operation processing at the left edge; Processing diagram showing logical operation processing at left edge FIG. 3 (a) Processing diagram showing logical operation processing at left edge (b) Processing diagram showing logical operation processing at left edge (c) Logical operation processing at left edge FIG. 4 is a processing diagram showing logical operation processing at the left edge. FIG. 5 is a weighting distribution diagram showing weighting distribution taking the left edge of the pixel to be processed as an example. FIG. 6 is a conversion table in the main scanning direction. FIG. 7 is a conversion table diagram showing a conversion table in the sub-scanning direction. FIG. 8A is an operation diagram in the main scanning direction as a result of performing the smoothing process. FIG. (C) Sub-scanning direction operation diagram as a result of performing smoothing processing (d) Sub-scanning direction operation diagram as a result of performing smoothing processing [FIG. 9] General image formation [FIG. 10] (a) Sample window diagram showing sample window (b) Sample window motion diagram showing movement of sample window [FIG. 11] (a) Edge detection method taking left edge as example (B) Edge detection method explanatory diagram for explaining the edge detection method taking the left edge as an example. FIG. 12 (a) Edge diagram showing various edges in the logical operation. Edge diagram showing various edges in calculation. [FIG. 13] Weighting distribution diagram showing weighting distribution. [FIG. 14] (a) Example of pattern for explaining failure. (B) A pattern diagram showing an example of a pattern for explaining the defect (c) A pattern diagram showing an example of the pattern for explaining the defect (d) A pattern showing an example of the pattern for explaining the defect FIG. 15E is a pattern diagram showing an example of a pattern for explaining a defect. FIG. 15A is a coordinate display diagram showing coordinate display for edge in the main scanning direction. FIG. 15B is a coordinate display showing coordinate display for edge in the sub scanning direction. FIG. 16A is a conversion table showing a conversion table in the main scanning direction obtained by using the processing control means. FIG. 16B is a conversion table showing a conversion table in the main scanning direction obtained by using the processing control means. FIG. 17 is a conversion table diagram showing a conversion table in the sub-scanning direction obtained by using the processing control means. FIG. 18A is an operation diagram in the main scanning direction as a result of performing a conventional smoothing process. b) Operation diagram in the main scanning direction as a result of performing the conventional smoothing process (c) Operation diagram in the sub scanning direction as a result of performing the conventional smoothing process (d) Sub-scanning as a result of performing the conventional smoothing process Directional operation diagram (e) Sub-scanning direction operation diagram as a result of conventional smoothing processing
DESCRIPTION OF SYMBOLS 1 Sample window setting means 2 Edge detection means 3 Logical operation means 4 Weighting operation means 5 Process control means 30 Process target pixel 31 Main scanning direction conversion table 32 Sub scanning direction conversion table

Claims (1)

Sample window setting means for setting a sample window centering on a pixel to be processed of an image before resolution enhancement processing;
Edge detection means for detecting an edge in the sample window;
Logical operation means for determining whether or not the detected edge is an edge to be multiplied by a weight by performing a logical operation determined at a predetermined location in the sample window;
Weighting calculation means for calculating a sum of weighted data values in the sample window by multiplying an edge determined as an edge to be multiplied by a weight in the logic calculation means by a weight distributed in the sample window;
A table holding a pattern composed of a combination of the minimum printable dots of the printer;
When the resolution that can be printed by the printer exceeds the resolution of the image data before the resolution improvement processing in the sub-scanning direction, depending on the sum of the weighted data values obtained by the weighting calculation means and the state of the surrounding edges By selecting one dot processing of the image data before the resolution enhancement processing from the patterns held in the table , the content of the selected processing is output without changing the print density and the print position. An image forming apparatus having processing control means.

Images