JP4162369B2 - Image reading apparatus, image forming apparatus, and image data processing method - Google Patents

Description

【００８３】
画像処理部５１で画像処理後の画像データＤwr０は、直ちに地肌除去部５２に入力するのではなく、一度画像メモリ５８に記憶される。画像メモリ５８により記憶装置を実現している。そして、スキャナユニット制御部３７のＣＰＵ５７は、画像メモリ５８に記憶された画像データＤwr０を呼び出し、コンパレータ５５をＯＮ、または、ＯＦＦにして地肌除去部５２に画像データＤwr０を出力することで、ユーザの選択に応じて、地肌除去部５２で地肌除去を行い、または、行わずに、露光器２２に出力することができる。このコンパレータ５５へのＣＰＵ５７からのコントロール信号の入力により選択手段を実現している。コンパレータ５５をＯＮ、ＯＦＦは、本体操作パネル３２の操作により行うので、本体操作パネル３２で入力装置を実現している。
【００８４】
すなわち、ＣＰＵ５７からのコントロール信号により、コンパレータ５５のＥＮ端子を制御することにより、次のようにしてコンパレータ５５をＯＮ、ＯＦＦすることができる。
【００８５】
コントロール信号がＨｉのとき：コンパレータＯＮ（地肌除去モード）
コントロール信号がＬｏｗのとき：コンパレータＯＦＦで出力レベルＨｉ固定（地肌除去モードの解除）
これにより、ＥＮ端子をＬｏｗにすると、セレクタ５６で常に画像データＤwr０が選択されるので、地肌除去部５２では画像データＤwr１を地肌除去することなく出力することができる。
【００８６】
図７は、前記のような信号処理を施すことで発生する画像データの変化を説明する説明図である。すなわち、画像データＤrd０は、図７（ａ），図７（ｄ）のような特性を有している。ここで、図７（ａ）は、画像濃度と読取画像データＤrd０との関係（γ特性）を示すもので、図７（ｄ）は、主走査方向に見た読取画像データＤrd０を示すものである。
【００８７】
画像データＤrd０に対して、前記のように画像処理部５１によりＭＴＦ補正やγ処理などを施され、それぞれ図７（ｂ）、図７（ｅ）に示すような特性になる。図７（ｂ）は、画像データＤrd０と、画像処理部５１による画像処理後の画像データＤwr０との関係（γ特性）を示し、図７（ｅ）は、主走査方向に見た画像処理部５１による画像処理後の読取画像データＤrd０を示すものである。画像処理部５１による画像処理後の検出データＤba'のレベルも示している。これにより、画像データがγ変換されていること、地肌レベルを示す検出信号のレベルがＤbaからＤba'に変更されていること、画像データのレベルが変更されていることがわかる。
【００８８】
次に、図７（ｃ）は、画像データＤrd０と、地肌除去部５２による地肌除去後の画像データＤwr１との関係（γ特性）を示し、図７（ｆ）は、主走査方向に見た地肌除去部５２による地肌除去後の画像データＤwr１を示すものである。閾値Ｄthのレベルも示している。これにより、地肌除去がされていること、画像データのレベルが保存されていることがわかる。
【００８９】
また、図７（ｂ）と図７（ｃ）との差は、γ変換そのものの機能であるといえる。そこで、イメージスキャナ２は、画像処理部５１で行う複数種類の画像処理、すなわち，ＭＴＦ補正、フィルタ処理、変倍処理、γ変換などのうち、γ変換を最後に行うようにしている。これによりγ変換機能を共有化して、画像濃度を保存したままで、閾値Ｄth周辺で違和感のない画像を提供することを、低コストで実現することができる。
【００９０】
このイメージスキャナ２では、検出データＤbaも画像データＤrd０に含めて、これらに単一の画像処理部５１により一括して画像処理を行うようにしているが、検出データＤbaと画像データＤrd０とに対し、別々の画像処理部で同じ画像処理を施すようにしてもよい。
【００９１】
しかし、本例のように単一の画像処理部５１により検出データＤbaも画像データＤrd０（画像データＤrd１）も処理することで、製造コストを低減し、また、検出データＤbaと画像データＤrd０とに、正確に同一の処理を施すことで、原稿の画像データの画像濃度の保存をより正確に行うことができる。
【００９２】
しかも、このイメージスキャナ２では、検出データＤbaを画像データＤrd０に含めて、この両データが合成された画像データＤrd１を単一の画像処理部５１に入力して画像処理を施すようにしたので、検出データＤbaと画像データＤrd０とを単一の画像処理部５１により一括して画像処理するのが容易である。
【００９３】
このイメージスキャナ２では、地肌検出部４６でゲート信号ＢａGATEを作成し、このゲート信号ＢａGATEを用いて画像データＤrd１から検出データＤba’を識別して取り出す手段を採用しているので、機種間でフィルタサイズが違うような場合でも、画像処理部５１や地肌除去部５２のアルゴリズムの共通化が図れ、システムを簡素化できる。
【００９４】
このイメージスキャナ２では、地肌検出部４６で検出され、合成部５０で画像データＤrd０に含められる検出データＤbaの画素数ｍの大きさを、後段の画像処理部５１でフィルタ処理に用いるフィルタマトリックスのサイズ以上としている。これにより、検出データＤbaを画像データＤrd０に含めてもフィルタ処理により影響を受けることなく、検出データＤba’を正確に維持し、地肌濃度を保存することができる。
【００９５】
この場合に、検出データＤbaを画像データＤrd０の有効画像期間ではなく、空転期間に付加するようにしてもよい。この場合は、比較的小さな検出データＤbaを画像データＤrd０に含めても、画像処理部５１におけるフィルタ処理により影響を受けることなく、検出データＤba’を正確に維持し、地肌濃度を保存することができる。
【００９６】
以上説明した原稿の画像を読み取ってからプリンタユニット３に出力するまでの一連の処理を整理して、図８のフローチャートを参照して説明する。
【００９７】
まず、本体操作パネル３２で原稿の複写を行う旨の所定の操作がなされることにより、図８の処理はスタートする。本体操作パネル３２では、原稿の複写を行うに際し地肌除去の実行を行うか否かについての選択を受付ける（ステップＳ１）。これにより受付工程を実現している。選択があったときは（ステップＳ１のＹ）、ＣＣＤ１３で原稿の画像を読み取り（ステップＳ２）、読み取った画像データに黒オフセット補正などの信号処理を信号処理部４１で行って（ステップＳ３）、Ａ／Ｄ変換器４２でＡ／Ｄ変換を行い（ステップＳ４）、白シェーディング補正部４４での白シェーディング補正（ステップＳ５）、黒シェーディング補正部４５での黒シェーディング補正（ステップＳ６）を行う。
【００９８】
そして、地肌検出ブロック４７で原稿の地肌レベルを検出し（ステップＳ７）、検出データＤbaを合成部５０で画像データＤrd０に付加する合成を行う（ステップＳ８）。ステップＳ６により地肌検出工程を実現し、ステップＳ７で合成工程を実現している。検出データＤbaを含む画像データＤrd１には、画像処理部５１で画像処理を施す（ステップＳ９）。ステップＳ８により第１および第２の画像処理工程を実現している。また、合成部５０でゲート信号ＢａGATEを生成して（ステップＳ１０）、ゲート信号生成工程を実現している。
【００９９】
この画像処理後の画像データＤrd０は、画像メモリ５８に記憶されて（ステップＳ１１）、記憶工程を実現する。本体操作パネル３２の所定の操作により地肌除去の実行の有無についての選択を予め受付けている。これにより受付工程を実現している。
【０１００】
地肌データ抽出部５３は、この画像処理後の画像データＤrd０からゲート信号ＢａGATEにより検出データＤba’を取り出し（ステップＳ１２）、ゲート信号特定工程を実現している。そして、オフセット部５４で閾値Ｄthを作成し（ステップＳ１３）、ステップＳ１で地肌除去の実行が選択されたときは（ステップＳ１４のＹ）、ＣＰＵ５７からのコントロール信号で、コンパレータ５５およびセレクタ５６により画像データＤwr０の地肌除去がなされる（ステップＳ１５）。また、ステップＳ１０で地肌除去の実行が選択されなかったたときは（ステップＳ１４のＮ）、ＣＰＵ５７からのコントロール信号で、コンパレータ５５をＯＦＦして、画像データＤwr０の地肌除去が行われない（ステップＳ１６）。ステップＳ１４により選択工程を、ステップＳ１５により地肌除去工程を実現している。
【０１０１】
［発明の実施の形態２］
この発明の別の実施の形態を発明の実施の形態２として説明する。
【０１０２】
発明の実施の形態１のイメージスキャナ２では、ゲート信号ＢａGATEを用いて画像データＤrd１から検出データＤba’を識別して取り出す手段を採用しているが、予め画像データＤrd１の各ラインの先頭に検出データＤbaを何画素分のデータとして付加するかを決めておくことで、ゲート信号BaGATEを用いない構成とすることもできる。この発明の実施の形態２は、かかる例を示すものである。
【０１０３】
以下の説明において、発明の実施の形態１と共通する回路要素などは同一符号を用い、詳細な説明を省略する。
【０１０４】
図９は地肌検出部４６の回路構成を示すブロック図であり、図１０は地肌除去部５２の回路構成を示すブロック図であり、図１１は各信号のタイミングチャートである。
【０１０５】
この例では、画像データＤwr０における検出データＤba’の位置をゲート信号ＢａGATEで特定するのでなく、画像データＤwr０における検出データＤba’の位置を、どの位置に何画素分のデータか予め設定しておくことにより特定するものである。すなわち、図９〜図１１に示すように、各ラインの画像データＤrd０における有効画像期間の先頭にｍ画素分のデータとして、ひとつ前のラインの検出データＤbaを付加するものである。具体的には画像処理部５１における画像処理を有効とするゲート信号であるゲート信号LGATE1の先頭ｍ画素分には、ひとつ前のラインの検出データＤbaを付加する。
【０１０６】
そのために、地肌検出部４６では、合成部５０にゲート信号LGATE1を入力して、検出データＤbaを付加した画像データＤrd１を作成する際に、ｍ画素分の検出データＤbaを含む各ラインの有効画像データの範囲を示すゲート信号であるゲート信号LGATE2を生成する。そして、地肌除去部５２では地肌データ抽出部５３の前段に地肌検出ゲート作成部６１を設け、この地肌検出ゲート作成部６１にゲート信号LGATE2を入力して、ゲート信号LGATE2から画像データＤwr０中のｍ画素分の検出データＤbaを特定するゲート信号（ＢａGATE）を生成して、地肌データ抽出部５３に出力するようにする。
【０１０７】
【発明の効果】
請求項１に記載の発明は、画像データも検出データも同じ画像処理を施して、この処理後の検出データで画像データの地肌除去を行うので、原稿の画像データの画像濃度を保存したままで、かつ、地肌除去に用いる閾値近辺でも違和感のない読取画像を得ることができる。
【０１０８】
請求項２に記載の発明は、請求項１に記載の画像読取装置において、画像データにγ変換を行っても、原稿の画像データの画像濃度を保存したままで、かつ、地肌除去に用いる閾値近辺でも違和感のない読取画像を得ることができる。
【０１０９】
請求項３に記載の発明は、請求項２に記載の画像読取装置において、地肌除去手段によるγ変換機能と第１の画像処理手段のγ変換機能を共有化して製造コストを低減することができる。
【０１１０】
請求項４に記載の発明は、請求項１〜３のいずれかの一に記載の画像読取装置において、画像データにＭＴＦ補正を行っても、原稿の画像データの画像濃度を保存したままで、かつ、地肌除去に用いる閾値近辺でも違和感のない読取画像を得ることができる。
【０１１１】
請求項５に記載の発明は、請求項１〜４のいずれかの一に記載の画像読取装置において、画像データにフィルタ処理を行っても、原稿の画像データの画像濃度を保存したままで、かつ、地肌除去に用いる閾値近辺でも違和感のない読取画像を得ることができる。
【０１１２】
請求項６に記載の発明は、請求項１〜５のいずれかの一に記載の画像読取装置において、画像データに対する画像処理と検出データに対する画像処理を正確に同じ内容にすることができ、原稿の画像データの画像濃度の保存を更に正確に行うことができる。
【０１１３】
また、画像データと検出データとを同一の画像処理手段で処理するのが容易となる。
【０１１４】
請求項７に記載の発明は、請求項１に記載の画像読取装置において、画像処理手段と地肌除去手段におけるアルゴリズムを共通化して、システムを簡素化することができる。
【０１１５】
また、小さな検出データを画像データに含めてもフィルタ処理により影響を受けることなく、検出データを正確に維持することができる。
【０１１６】
請求項８に記載の発明は、請求項１に記載の画像読取装置において、検出データを画像データに含めてもフィルタ処理により影響を受けることなく、検出データを正確に維持することができる。
【０１１７】
請求項９に記載の発明は、請求項１〜８のいずれかの一に記載の画像読取装置において、画像処理後の画像データを記憶しておいて、選択的に地肌除去を行ったり、行わなかったりすることができる。
【０１１８】
請求項１０に記載の発明は、請求項１〜９のいずれかの一に記載の同様の作用、効果を奏することができる。
【０１１９】
請求項１１に記載の発明は、画像データも検出データも同じ画像処理を施すので、この処理後の検出データで画像データの地肌除去を行うことが可能となり、原稿の画像データの画像濃度を保存したままで、かつ、地肌除去に用いる閾値近辺でも違和感のない読取画像を得ることができる。
【０１２０】
請求項１２に記載の発明は、請求項１１に記載の画像データ処理方法において、画像データにγ変換を行っても、原稿の画像データの画像濃度を保存したままで、かつ、地肌除去に用いる閾値近辺でも違和感のない読取画像を得ることができる。
【０１２１】
請求項１３に記載の発明は、請求項１２に記載の画像データ処理方法において、地肌除去工程によるγ変換機能と第１の画像処理工程のγ変換機能を共有化して製造コストを低減することができる。
【０１２２】
請求項１４に記載の発明は、請求項１１〜１３のいずれかの一に記載の画像データ処理方法において、画像データにＭＴＦ補正を行っても、原稿の画像データの画像濃度を保存したままで、かつ、地肌除去に用いる閾値近辺でも違和感のない読取画像を得ることができる。
【０１２３】
請求項１５に記載の発明は、請求項１１〜１４のいずれかの一に記載の画像データ処理方法において、画像データにフィルタ処理を行っても、原稿の画像データの画像濃度を保存したままで、かつ、地肌除去に用いる閾値近辺でも違和感のない読取画像を得ることができる。
【０１２４】
請求項１６に記載の発明は、請求項１１〜１５のいずれかの一に記載の画像データ処理方法において、画像データに対する画像処理と検出データに対する画像処理を正確に同じ内容にすることができ、原稿の画像データの画像濃度の保存を更に正確に行うことができる。
【０１２５】
また、画像データと検出データとを同一の画像処理手段で処理するのが容易となる。
【０１２６】
請求項１７に記載の発明は、請求項１１に記載の画像データ処理方法において、画像処理工程と地肌除去工程におけるアルゴリズムを共通化して、システムを簡素化することができる。
【０１２７】
また、小さな検出データを画像データに含めてもフィルタ処理により影響を受けることなく、検出データを正確に維持することができる。
【０１２８】
請求項１８に記載の発明は、請求項１１〜１７のいずれかの一に記載の画像データ処理方法において、検出データを画像データに含めてもフィルタ処理により影響を受けることなく、検出データを正確に維持することができる。
【０１２９】
請求項１９に記載の発明は、請求項１１〜１８のいずれかの一に記載の画像データ処理方法において、画像処理後の画像データを記憶しておいて、選択的に地肌除去を行ったり、行わなかったりすることができる。
【図面の簡単な説明】
【図１】この発明の実施の形態１である複写機の概略構成を示す断面図である。
【図２】前記複写機の制御系の電気的な接続を示すブロック図である。
【図３】前記複写機のイメージスキャナの信号処理を行う回路のブロック図である。
【図４】前記イメージスキャナの地肌検出部の回路のブロック図である。
【図５】前記イメージスキャナの各信号のタイミングチャートである。
【図６】前記イメージスキャナの地肌除去部の回路のブロック図である。
【図７】前記イメージスキャナの地肌除去処理などを説明する説明図である。
【図８】前記信号処理の手順を説明するフローチャートである。
【図９】この発明の実施の形態２である複写機のイメージスキャナで用いる地肌検出部の回路のブロック図である。
【図１０】前記イメージスキャナ地肌除去部の回路のブロック図である。
【図１１】前記イメージスキャナの各信号のタイミングチャートである。
【図１２】発明の課題を説明する説明図である。
【符号の説明】
１ 画像形成装置
２ 画像読取装置
１３ 光電変換素子
３２ 入力装置
５０ 合成手段、ゲート信号生成手段
５１ 第１および第２の画像処理手段
５２ 地肌除去手段
５３ ゲート信号特定手段
５８ 記憶装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus, an image forming apparatus, and an image data processing method.
[0002]
[Prior art]
Japanese Patent Application Laid-Open No. 6-311359 discloses a background removing apparatus that removes the background of an original from image data after shading correction and before predetermined image processing. In this technique, not only image data below a predetermined threshold value is simply removed as the background of the document, but also a process of gradually skipping (changing) the threshold value is performed, so that the image in the density portion around the threshold value is processed. I try to reduce the sense of incongruity.
[0003]
[Problems to be solved by the invention]
However, the technique disclosed in Japanese Patent Application Laid-Open No. 6-311359 is configured to detect the background level of the document from the image data after shading correction and cut the image data at a predetermined threshold, so that the image density is almost preserved. However, since γ greatly changes in the vicinity of the threshold value, the image having the density in the vicinity of the threshold value is changed due to the influence of the subsequent image processing, resulting in a feeling of strangeness.
[0004]
The essence of image discomfort due to the image data being cut at the threshold value is that an unnatural data inflection point occurs in the image data around the threshold value, and MTF correction or smoothing is performed on the image data by subsequent image processing. The inflection point is to be emphasized more by doing. FIG. 12 shows an example of changes in image data after MTF correction when the image data is changed with a threshold value and when it is normal. That is, the image data when the MTF correction is directly performed on the image data shown in FIG. 12A is as shown in FIG. 12B, whereas the image data shown in FIG. As shown in FIG. 12D, the inflection point is further emphasized in the image data when the MTF correction is performed after changing the threshold value as shown in c).
[0005]
In the technique disclosed in Japanese Patent Application Laid-Open No. 6-311359, as a countermeasure, the γ around the threshold is gradually changed as described above, thereby suppressing a rapid change in the image data around the threshold. In this image processing, an attempt is made to prevent an adverse effect on the image due to MTF correction or smoothing, but there is a problem that it cannot be completely eliminated. In addition, since γ is changed around the threshold, there is a problem that image density cannot be stored around the threshold.
[0006]
In order to remove the background of the document, it is also conceivable to detect the background level from the analog image data with a peak hold circuit and feed back the value to the reference value of the A / D converter.
[0007]
However, with such a means, the reading density changes depending on the brightness of the document due to the influence of the black offset level and the offset of the amplifier or the like.
[0008]
That is, for example, when the gain of the peak hold circuit is A, and the value of the image data after black offset subtraction with the digital amount after A / D conversion,
"Output after A / D conversion of background level"-"Output after A / D conversion of black level"
= "Background level + Black level + Offset voltage" / "A / D conversion reference
Voltage "-" black level + offset voltage "/" reference voltage for A / D conversion "
= ((D + Vb + Voff)-(Vb + Voff)) / A (D + Vb + Voff)
= D / A (D + Vb + Voff)
D: Document background reading (analog amount)
Vb: Black offset level
Voff: Offset of amplifier etc.
Thus, it can be seen that the value of the digital image data after the background removal varies depending on the background density D of the document. For this reason, there is a problem in that the degree of background change changes depending on the background density.
[0009]
An object of the present invention is to provide a read image that can store the image density of image data of a document and that does not feel uncomfortable even in the vicinity of a threshold used for background removal.
[0010]
An object of the present invention is to obtain a read image that retains the image density of the image data of the original document even if the γ conversion is performed on the image data, and has no sense of incongruity even in the vicinity of the threshold used for background removal.
[0011]
An object of the present invention is to reduce the manufacturing cost by sharing the γ conversion function.
[0012]
An object of the present invention is to obtain a read image that retains the image density of the image data of the original document even when MTF correction is performed on the image data, and has no sense of incongruity even in the vicinity of the threshold used for background removal.
[0013]
SUMMARY OF THE INVENTION An object of the present invention is to obtain a read image that retains the image density of image data of a document even when filtering is performed on the image data, and that does not feel uncomfortable even in the vicinity of a threshold value used for background removal.
[0014]
An object of the present invention is to more accurately store the image density of image data of a document.
[0015]
An object of the present invention is to facilitate processing of image data and detection data by the same image processing means.
[0016]
An object of the present invention is to simplify the system by sharing an algorithm in the image processing means and the background removal means.
[0017]
An object of the present invention is to accurately maintain detection data even if small detection data is included in image data.
[0018]
An object of the present invention is to accurately maintain detection data even if the detection data is included in image data.
[0019]
An object of the present invention is to store image data after image processing so that the background can be selectively removed or not.
[0020]
[Means for Solving the Problems]
The invention according to claim 1 is a reading unit that reads an image of a document, a background detection unit that detects a background level of the document from image data of the read document, The detection data of the background level in each line output from the background detection means is the next line. Effective image data of image data At the beginning of In addition, an adding means for outputting together with data indicating the location of the detection data of the background level, an image processing means for performing one or more types of image processing on the image data to which the detection data of the background level is added, Based on the data indicating the presence position of the detection data of the background level, the detection data indicating the background level is obtained from the image data after the image processing output from the image processing means, and the detection data indicating the background level and the image An image reading apparatus comprising: background removal means for removing the background of the image data output from the image processing means based on the image data after image processing output from the processing means.
[0021]
Therefore, the image data and the detection data are subjected to the same image processing, and the background of the image data is removed by the detection data after the processing. Therefore, the image density of the image data of the original is kept and used for the background removal. Even in the vicinity of the threshold value, it is possible to obtain a read image with no sense of discomfort.
[0022]
In this specification, “image processing for realizing user-preferred image quality” includes, for example, γ conversion, MTF correction, filter processing, scaling processing, and the like, in order to maintain a certain level of image quality. Processing that is inevitably required, such as white shading correction and black shading correction, is not included.
[0023]
According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, one type of the image processing is γ conversion.
[0024]
Therefore, even if γ conversion is performed on the image data, it is possible to obtain a read image that retains the image density of the image data of the original and does not feel uncomfortable even in the vicinity of the threshold used for background removal.
[0025]
According to a third aspect of the present invention, in the image reading apparatus according to the second aspect, the image processing includes a plurality of types. Drawing The image processing means performs the γ conversion last among the plurality of types of image processing.
[0026]
Therefore, it is possible to reduce the manufacturing cost by sharing the γ conversion function of the background removing unit and the γ conversion function of the first image processing unit.
[0027]
According to a fourth aspect of the present invention, in the image reading apparatus according to any one of the first to third aspects, one type of the image processing is MTF correction.
[0028]
Therefore, even if MTF correction is performed on the image data, it is possible to obtain a read image that maintains the image density of the image data of the original and that does not feel uncomfortable even near the threshold used for background removal.
[0029]
According to a fifth aspect of the present invention, in the image reading apparatus according to any one of the first to fourth aspects, one type of the image processing is filter processing.
[0030]
Therefore, even if the image data is subjected to the filtering process, it is possible to obtain a read image that retains the image density of the image data of the original and that does not feel uncomfortable even in the vicinity of the threshold used for background removal.
[0031]
According to a sixth aspect of the present invention, in the image reading apparatus according to any one of the first to fifth aspects, Drawing The image processing means Detection data and image data of the background level The same image processing means for performing the image processing.
[0032]
Therefore, the image processing for the image data and the image processing for the detection data can be made exactly the same content, and the image density of the image data of the original can be stored more accurately.
[0033]
in front Record Addition The means adds the background level detection data of each line to the effective image data of the image data of the next line.
[0034]
Therefore, it becomes easy to process the image data and the detection data by the same image processing means.
[0035]
Claim 7 The invention described in claim 1 In the image reading apparatus according to claim 1, Addition The means generates a gate signal for specifying the background level detection data included in the image data when adding the background level detection data to the image data, and the background removal means includes the background level The background level detection data included in the image data to which the detection data is added is specified and extracted based on the gate signal.
[0036]
Therefore, it is possible to simplify the system by sharing an algorithm in the image processing unit and the background removal unit.
[0037]
Picture One type of image processing is filtering, Addition The means adds the background level detection data to the idling period portion of the image data.
[0038]
Therefore, even if small detection data is included in the image data, the detection data can be accurately maintained without being affected by the filtering process.
[0039]
Claim 8 The invention described in claim 1 In the image reading apparatus according to claim 1, one type of the image processing is filter processing, Addition The means adds the detection data to the image valid period portion of the image data, and the background level is equal to or larger than the size of the filter matrix used for the filter processing.
[0040]
Therefore, even if the detection data is included in the image data, the detection data can be accurately maintained without being affected by the filtering process.
[0041]
Claim 9 The invention described in claim 1 8 In the image reading device according to any one of the above, a storage device that stores the image data after the image processing, an input device that accepts selection of presence / absence of background removal for the image data, and execution of the background removal are selected The image data stored in the storage device is subject to the background removal by the background removal means when the image is stored, and the image data stored in the storage device is selected when the execution of the background removal is not selected. And selecting means for not subjecting the background to the background removal by the background removal means.
[0042]
Therefore, the image data after the image processing can be stored, and the background removal can be selectively performed or not performed.
[0043]
Claim 1 0 The invention described in claim 1 9 An image forming apparatus including the image reading apparatus according to any one of the above, and performing image formation on a sheet based on image data read by the image reading apparatus.
[0044]
Accordingly, claims 1 to 9 The same operations and effects as described in any one of the above can be achieved.
[0045]
Claim 11 The invention described in 1), a background detection step of detecting the background level of the document from the image data of the read document;
The detection data of the background level in each detected line is Effective image data of image data At the beginning of In addition, an addition step of outputting together with data indicating the location of the detection data of the background level, an image processing step of performing one or more types of image processing on the image data to which the detection data of the background level is added, A background level detecting step for obtaining detection data indicating a background level from image data after image processing obtained by the image processing step based on data indicating a position where the detection data of the background level is present, and the background level detecting step A background removal step of removing the background of the image data obtained by the image processing step based on the detection data indicating the background level obtained by the above and the image data after the image processing obtained by the image processing step. This is an image data processing method.
[0046]
Therefore, since the same image processing is performed for both the image data and the detection data, it is possible to remove the background of the image data with the detection data after this processing, and the image density of the image data of the document is preserved and the background is preserved. Even in the vicinity of the threshold used for removal, it is possible to obtain a read image with no sense of incongruity.
[0047]
Claim 12 The invention described in claim 11 In the image data processing method described in 1), one type of the image processing is γ conversion.
[0048]
Therefore, even if γ conversion is performed on the image data, it is possible to obtain a read image that retains the image density of the image data of the original and does not feel uncomfortable even in the vicinity of the threshold used for background removal.
[0049]
Claim 13 The invention described in claim 12 In the image data processing method according to claim 1, the image processing includes a plurality of types, Drawing In the image processing step, the γ conversion is finally performed among the plurality of types of image processing.
[0050]
Therefore, it is possible to reduce the manufacturing cost by sharing the γ conversion function of the background removal process and the γ conversion function of the first image processing process.
[0051]
Claim 14 The invention described in claim 11 ~ 13 In the image data processing method according to any one of the above, one type of the image processing is MTF correction.
[0052]
Therefore, even if MTF correction is performed on the image data, it is possible to obtain a read image that maintains the image density of the image data of the original and that does not feel uncomfortable even near the threshold used for background removal.
[0053]
Claim 15 The invention described in claim 11 ~ 14 In the image data processing method according to any one of the above, one type of the image processing is filter processing.
[0054]
Therefore, even if the image data is subjected to the filtering process, it is possible to obtain a read image that retains the image density of the image data of the original and that does not feel uncomfortable even in the vicinity of the threshold used for background removal.
[0055]
Claim 16 The invention described in claim 11 ~ 15 In the image data processing method according to any one of the above, the image processing step is performed collectively by performing the image processing on the background level detection data and the image data.
[0056]
Therefore, the image processing for the image data and the image processing for the detection data can be made exactly the same content, and the image density of the image data of the original can be stored more accurately.
[0057]
Addition In the step, before the processing in the image processing step, the detection data of the background level in each line is added to the effective image data of the image data of the next line.
[0058]
Therefore, it becomes easy to process the image data and the detection data by the same image processing means.
[0059]
Claim 17 The invention described in claim 11 In the image data processing method according to claim 1, Addition In the step, when the background level detection data is added to the image data, a gate signal for specifying the background level detection data included in the image data is generated, and in the background level detection step, the background level is detected. The background level detection data included in the image data to which the level detection data is added is specified and extracted based on the gate signal.
[0060]
Therefore, it is possible to simplify the system by sharing an algorithm in the image processing step and the background removal step.
[0061]
Picture One type of image processing is filtering, Addition In the process, the detection data is added to the idling period portion of the image data.
[0062]
Therefore, even if small detection data is included in the image data, the detection data can be accurately maintained without being affected by the filtering process.
[0063]
Claim 18 The invention described in claim 11 In the image data processing method according to claim 1, one type of the image processing is filter processing, Addition In the process, the detection data is added to the image valid period portion of the image data, and the background level is set to be equal to or larger than the size of the filter matrix used for the filter processing.
[0064]
Therefore, even if the detection data is included in the image data, the detection data can be accurately maintained without being affected by the filtering process.
[0065]
Claim 19 The invention described in claim 11 ~ 18 In the image data processing method according to any one of the above, a storage step of storing the image data after the image processing in a storage device, a reception step of accepting selection of presence / absence of background removal for the image data, and the background removal When the execution of the background is selected, the image data stored in the storage device is the target of the background removal by the background removal step, and when the execution of the background removal is not selected, the image data is stored in the storage device. And a selection step in which the image data is not subject to the background removal by the background removal step.
[0066]
Therefore, the image data after the image processing can be stored, and the background removal can be selectively performed or not performed.
[0067]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 of the Invention
An embodiment of the present invention will be described as Embodiment 1 of the present invention.
[0068]
1 is a side sectional view showing a schematic configuration of a copying machine according to Embodiment 1 of the present invention. The copier 1 implements the image forming apparatus according to the present invention. The image forming apparatus according to the present invention is an image reading apparatus according to the present invention. A printer unit 3 that performs printing on paper, and an ADF (Automatic Document Feeder) 4 provided on the image scanner 2.
[0069]
A contact glass 5 on which a document to be read is placed is provided on the upper surface of the image scanner 2. Below the contact glass 5, a first carriage 8 that includes the illumination lamp 6 and the mirror 7 and can travel along the contact glass 5, and a second carriage that includes the mirrors 9 and 10 and can travel along the contact glass 5. A scanning optical system 14 including a carriage 11, an imaging lens 12, and a CCD (Charge Coupled Device) 13 that is a photoelectric conversion element is provided. The first and second carriages 8 and 11 are driven by a carriage motor (not shown) such as a stepping motor, and travel from the home position (right side) shown in FIG. 1 to the left side at a speed ratio of 2: 1.
[0070]
The printer unit 3 includes a paper transport path from a paper feed tray 15 for stacking papers to a paper discharge stacker unit 18 via a printer engine 16 for forming an image on the paper by an electrophotographic method, a fixing device 17 and the like. 19 is formed. The printer engine 16 exposes the photoconductor 20 based on image data read by the image scanner 2, a charger 21 that uniformly charges the surface of the photoconductor 20, and the image scanner 2 to form an electrostatic latent image. The exposure unit 22, the developing unit 23 that develops the electrostatic latent image formed on the surface of the photoconductor 20 with toner, and the toner image on the photoconductor 20 is transferred to the paper conveyed through the paper conveyance path 19. And a transfer device 24.
[0071]
The ADF 4 includes a document table 25 on which a document to be fed to the contact glass 5 by the ADF 4 is placed, and a paper discharge unit 26 from which the scanned document is discharged. A document transport path 27 that communicates from the document table 25 to the paper discharge unit 26 is formed inside the ADF 4. A transport mechanism 31 such as an endless belt 29 wound around a plurality of pairs of rollers 28 and a transport roller 30 is provided in the document transport path 27. The transport mechanism 31 is driven by an ADF motor (not shown) such as a stepping motor, and transports the documents placed on the document table 25 one by one toward the contact glass 5. A main body operation panel 32 having a keyboard and a display is provided on the upper surface of the ADF 4.
[0072]
Next, the electrical connection of the control system of the copying machine 1 will be described with reference to FIG. The copying machine 1 includes a main control unit 33 that has a CPU and centrally drives and controls each unit in the copying machine 1. Connected to the main control unit 33 are a main body operation panel control unit 34 that controls the main body operation panel 32, a scanner unit control unit 37 that controls the image scanner 2, and a printer unit control unit 36 that controls the printer unit 3. Has been.
[0073]
The main body operation panel control unit 34 outputs an input signal corresponding to the input operation with the keyboard on the main body operation panel 32 to the main control unit 33. Further, the main body operation panel control unit 34 causes the display to display information based on the display data output from the main control unit 33.
[0074]
The scanner unit control unit 37 outputs image data of a document optically read by the CCD 13 to the main control unit 35 as image data converted into an electric signal. An ADF control unit 38 is connected to the scanner unit control unit 37, and the ADF control unit 38 contacts an original by driving an ADF motor (not shown) according to a signal output from the scanner unit control unit 37. Feed to glass 5.
[0075]
When the image data output from the main control unit 33 is input, the printer unit control unit 36 drives and controls each unit in the printer unit 3, and adjusts the timing from the paper feed tray 15 to the conveyed paper. Then, an image based on the formed image data acquired in the code identification image forming process described later is formed.
[0076]
FIG. 3 is a block diagram of a circuit that performs signal processing of the image scanner 2. As shown in FIG. 3, analog image data output from the CCD 13 is subjected to black offset correction or the like by the signal processing unit 41, A / D converted by the A / D converter 42, and converted into digital image data, and then shading. Black shading correction is performed by the black shading correction unit 45 of the unit 43, white shading correction is performed by the white shading correction unit 44, and output as image data Drd0 in which uneven illumination and uneven sensitivity of the CCD 13 are corrected. The white shading correction is performed based on shading data obtained by reading a white reference plate (not shown) before reading the document.
[0077]
The image data Drd0 is input to the next background detection unit 46, and the background detection block 47 detects the background level of the document in the image data Drd0. That is, as shown in FIG. 4, in the background detection block 47, the smoothing filter 48 removes the influence of the noise of the image data Drd0, and the peak value of the image data Drd0 output from the smoothing filter 48 is detected by the peak hold circuit 49. By doing so, the background level of the document can be accurately detected. A background detection means is realized by the background detection block 47. In order to detect the background of the document, document size information is required to specify the region of the document image in the image data or the region where the background can be reliably detected. The document size signal indicating the document size information is output from the CPU of the scanner unit control unit 37 to the background detection unit 46 by detecting the document size by an optical sensor (not shown).
[0078]
The detection data Dba indicating the background level of the document output from the background detection block 47 and the image data Drd0 are input to the combining unit 50. The synthesizer 50 adds the detection data Dba to the image data Drd0. For example, as shown in FIG. 5, detection data Dba in each line is added to the beginning of the effective image data of the next line of image data Drd0 for m pixels to obtain image data Drd1. Combining means is realized by the combining unit 50. The image data Drd1 is output to the image processing unit 51 at the next stage of the background detection unit 46. At the same time, the synthesizer 50 generates and outputs a gate signal BaGATE that is a gate signal indicating the position of the detection data Dba in the image data Drd1. Therefore, the synthesizing unit 50 realizes a gate signal generating unit.
[0079]
The image data Drd1 output from the background detection unit 46 is processed by the image processing unit 51 in one or more types of image processing for realizing the user's preferred image quality. In this example, MTF correction, filter processing, and scaling processing are performed. , Γ conversion, etc., and output as image data Dwr0 and input to the background removal unit 52. The image processing unit 51 implements first and second image processing means. The γ correction can be set by a density adjustment key on the operation panel 32. The scaling process is executed by setting a scaling ratio using a scaling key on the operation panel 32. Further, the MTF correction or filter processing corresponding to the character original or the photo original is executed by operating the character original / photo original switching key on the operation panel 32.
[0080]
As shown in FIG. 6, in the background removal unit 52, the background data extraction unit 53 detects detection data Dba ′ indicating the background level from the image data Dwr0 after the image processing by the image processing unit 51 using the gate signal BaGATE. . The background data extraction unit 53 realizes a gate signal specifying unit. Then, if the detection data Dba ′ is used as a threshold value for the background removal processing, the background noise may be output. Therefore, the next offset unit 54 in the background data extraction unit 53 (1) ) By subtracting a certain offset from the image data Dwr0 and then subtracting a certain percentage by the equation (2),
Dth = Dba′−offset (1)
Dth = Dba ′ × (1-α) (2)
Or, by combining the expression (1) and the expression (2) by the expression (3),
Dth = Dba ′ × (1-α) −offset (3)
By using such means as described above, the influence of noise of the detection data Dba ′ is removed by obtaining the threshold value Dth used for removing the background level.
[0081]
Thereafter, the threshold value Dth and the image data Dwr0 obtained as described above are input to the A input and the B input of the comparator 55, respectively, and the threshold value Dth and the image data Dwr0 are compared with each other, as shown in Table 1. Control the output of. Since one of the image data Dwr0 and the white level FFh is selectively output by the selector 56 by the output of the comparator 55 (when 1 is input to the S terminal of the selector 56, the image data Dwr0 is When 0 is input, white level FFh is output), and background removal processing can be performed. The background removal unit 52 realizes a background removal means. In this case, both the image data Drd1 and the detection data Dba are subjected to the same image processing by the image processing unit 51, and the background of the processed image data Dwr0 is removed by the detection data Dba ′ after this processing. An image having no sense of incongruity around the threshold Dth can be provided while being stored.
[0082]
[Table 1]

[0083]
The image data Dwr0 after image processing by the image processing unit 51 is not immediately input to the background removal unit 52 but is once stored in the image memory 58. A storage device is realized by the image memory 58. Then, the CPU 57 of the scanner unit control unit 37 calls the image data Dwr0 stored in the image memory 58, turns the comparator 55 ON or OFF, and outputs the image data Dwr0 to the background removal unit 52. Depending on the selection, the background removal unit 52 can perform the background removal or can output it to the exposure device 22 without performing the background removal. Selection means is realized by inputting a control signal from the CPU 57 to the comparator 55. Since the comparator 55 is turned on and off by operating the main body operation panel 32, an input device is realized by the main body operation panel 32.
[0084]
That is, by controlling the EN terminal of the comparator 55 with a control signal from the CPU 57, the comparator 55 can be turned on and off as follows.
[0085]
When control signal is Hi: Comparator ON (background removal mode)
When the control signal is Low: Output level Hi is fixed when the comparator is OFF (cancellation of background removal mode)
Thus, when the EN terminal is set to Low, the image data Dwr0 is always selected by the selector 56, so that the background removal unit 52 can output the image data Dwr1 without removing the background.
[0086]
FIG. 7 is an explanatory diagram for explaining a change in image data generated by performing the signal processing as described above. That is, the image data Drd0 has characteristics as shown in FIGS. 7 (a) and 7 (d). Here, FIG. 7A shows the relationship (γ characteristic) between the image density and the read image data Drd0, and FIG. 7D shows the read image data Drd0 viewed in the main scanning direction. is there.
[0087]
As described above, the image processing unit 51 performs MTF correction, γ processing, and the like on the image data Drd0, and has characteristics as shown in FIGS. 7B and 7E, respectively. FIG. 7B shows the relationship (γ characteristics) between the image data Drd0 and the image data Dwr0 after image processing by the image processing unit 51, and FIG. 7E shows the image processing unit viewed in the main scanning direction. The read image data Drd0 after the image processing by 51 is shown. The level of detection data Dba ′ after image processing by the image processing unit 51 is also shown. As a result, it can be seen that the image data has been γ-transformed, the level of the detection signal indicating the background level has been changed from Dba to Dba ′, and the level of the image data has been changed.
[0088]
Next, FIG. 7C shows the relationship (γ characteristics) between the image data Drd0 and the image data Dwr1 after the background removal by the background removal unit 52, and FIG. 7F is viewed in the main scanning direction. The image data Dwr1 after the background removal by the background removal part 52 is shown. The level of the threshold value Dth is also shown. As a result, it is understood that the background has been removed and the level of the image data is stored.
[0089]
Moreover, it can be said that the difference between FIG. 7B and FIG. 7C is a function of the γ conversion itself. Therefore, the image scanner 2 performs γ conversion lastly among a plurality of types of image processing performed by the image processing unit 51, that is, MTF correction, filter processing, scaling processing, γ conversion, and the like. As a result, it is possible to realize at low cost that the γ conversion function is shared and an image having no sense of incongruity is provided around the threshold Dth while the image density is preserved.
[0090]
In this image scanner 2, the detection data Dba is also included in the image data Drd 0, and image processing is collectively performed by the single image processing unit 51. However, the detection data Dba and the image data Drd 0 are processed with respect to the detection data Dba and the image data Drd 0. The same image processing may be performed by different image processing units.
[0091]
However, as shown in this example, the detection data Dba and the image data Drd0 (image data Drd1) are processed by the single image processing unit 51, thereby reducing the manufacturing cost, and the detection data Dba and the image data Drd0. By performing exactly the same processing, it is possible to more accurately store the image density of the image data of the document.
[0092]
Moreover, in the image scanner 2, the detection data Dba is included in the image data Drd0, and the image data Drd1 obtained by combining the two data is input to the single image processing unit 51 to perform image processing. It is easy to perform image processing of the detection data Dba and the image data Drd0 collectively by the single image processing unit 51.
[0093]
In this image scanner 2, since the background detection unit 46 creates a gate signal BaGATE and uses the gate signal BaGATE to identify and extract the detection data Dba ′ from the image data Drd1, it is possible to filter between models. Even when the sizes are different, the algorithms of the image processing unit 51 and the background removal unit 52 can be shared, and the system can be simplified.
[0094]
In this image scanner 2, the size of the number of pixels m of the detection data Dba detected by the background detection unit 46 and included in the image data Drd 0 by the synthesis unit 50 is used as the filter matrix used for the filter processing by the subsequent image processing unit 51. More than size. Thus, even if the detection data Dba is included in the image data Drd0, the detection data Dba ′ can be accurately maintained and the background density can be preserved without being affected by the filter processing.
[0095]
In this case, the detection data Dba may be added to the idling period instead of the effective image period of the image data Drd0. In this case, even if relatively small detection data Dba is included in the image data Drd0, the detection data Dba ′ can be accurately maintained and the background density can be preserved without being affected by the filter processing in the image processing unit 51. it can.
[0096]
A series of processes from reading the image of the original document described above to outputting it to the printer unit 3 will be organized and described with reference to the flowchart of FIG.
[0097]
First, the processing of FIG. 8 starts when a predetermined operation for copying a document is performed on the main body operation panel 32. The main body operation panel 32 accepts a selection as to whether or not to perform background removal when copying a document (step S1). This realizes the reception process. When selected (Y in Step S1), the image of the original is read by the CCD 13 (Step S2), and signal processing such as black offset correction is performed on the read image data by the signal processing unit 41 (Step S3). The A / D converter 42 performs A / D conversion (step S4), the white shading correction unit 44 performs white shading correction (step S5), and the black shading correction unit 45 performs black shading correction (step S6).
[0098]
Then, the background detection block 47 detects the background level of the document (step S7), and the combining unit 50 adds the detection data Dba to the image data Drd0 (step S8). The background detection process is realized by step S6, and the synthesis process is realized by step S7. The image processing unit 51 performs image processing on the image data Drd1 including the detection data Dba (step S9). Step S8 realizes the first and second image processing steps. Further, the synthesizing unit 50 generates the gate signal BaGATE (step S10), thereby realizing the gate signal generating step.
[0099]
The image data Drd0 after the image processing is stored in the image memory 58 (step S11), and a storage process is realized. A selection as to whether or not the background removal is performed is received in advance by a predetermined operation of the main body operation panel 32. This realizes the reception process.
[0100]
The background data extraction unit 53 extracts the detection data Dba ′ from the image data Drd0 after the image processing using the gate signal BaGATE (step S12), thereby realizing a gate signal specifying step. Then, the threshold value Dth is created by the offset unit 54 (step S13), and when the execution of the background removal is selected in step S1 (Y in step S14), an image is output by the comparator 55 and the selector 56 with a control signal from the CPU 57. The background of the data Dwr0 is removed (step S15). If the execution of the background removal is not selected in Step S10 (N in Step S14), the comparator 55 is turned off by the control signal from the CPU 57, and the background removal of the image data Dwr0 is not performed (Step S14). S16). The selection process is realized by step S14, and the background removal process is realized by step S15.
[0101]
[Embodiment 2 of the Invention]
Another embodiment of the present invention will be described as a second embodiment of the present invention.
[0102]
In the image scanner 2 according to the first embodiment of the present invention, a means for identifying and extracting the detection data Dba ′ from the image data Drd1 using the gate signal BaGATE is employed, but is detected in advance at the head of each line of the image data Drd1. By determining how many pixels of data Dba should be added, it is possible to adopt a configuration in which the gate signal BaGATE is not used. Embodiment 2 of the present invention shows such an example.
[0103]
In the following description, the same reference numerals are used for circuit elements common to the first embodiment of the invention, and detailed description thereof is omitted.
[0104]
9 is a block diagram showing a circuit configuration of the background detection unit 46, FIG. 10 is a block diagram showing a circuit configuration of the background removal unit 52, and FIG. 11 is a timing chart of each signal.
[0105]
In this example, the position of the detection data Dba ′ in the image data Dwr0 is not specified by the gate signal BaGATE, but the position of the detection data Dba ′ in the image data Dwr0 is set in advance to which position how many pixels worth of data. It is specified by this. That is, as shown in FIGS. 9 to 11, the detection data Dba of the previous line is added as data for m pixels at the beginning of the effective image period in the image data Drd0 of each line. Specifically, the detection data Dba of the previous line is added to the first m pixels of the gate signal LGATE1, which is a gate signal that enables image processing in the image processing unit 51.
[0106]
Therefore, in the background detection unit 46, when the gate signal LGATE1 is input to the synthesis unit 50 and the image data Drd1 to which the detection data Dba is added is generated, an effective image of each line including the detection data Dba for m pixels is generated. A gate signal LGATE2, which is a gate signal indicating a data range, is generated. In the background removal unit 52, a background detection gate creation unit 61 is provided in front of the background data extraction unit 53, and the gate signal LGATE2 is input to the background detection gate creation unit 61, and m in the image data Dwr0 is input from the gate signal LGATE2. A gate signal (BaGATE) for specifying the detection data Dba for the pixels is generated and output to the background data extraction unit 53.
[0107]
【The invention's effect】
According to the first aspect of the present invention, the same image processing is applied to both the image data and the detection data, and the background of the image data is removed by the detection data after this processing. Therefore, the image density of the image data of the document is stored. In addition, it is possible to obtain a read image having no sense of incongruity even in the vicinity of the threshold used for removing the background.
[0108]
According to a second aspect of the present invention, in the image reading device according to the first aspect, the threshold used for removing the background while maintaining the image density of the image data of the original document even when the image data is subjected to γ conversion. It is possible to obtain a read image without a sense of incongruity even in the vicinity.
[0109]
According to a third aspect of the present invention, in the image reading apparatus according to the second aspect, the gamma conversion function by the background removal means and the gamma conversion function of the first image processing means can be shared to reduce the manufacturing cost. .
[0110]
According to a fourth aspect of the present invention, in the image reading apparatus according to any one of the first to third aspects, the image density of the image data of the document is stored even when the MTF correction is performed on the image data. In addition, it is possible to obtain a read image having no sense of incongruity even in the vicinity of the threshold used for removing the background.
[0111]
According to a fifth aspect of the present invention, in the image reading apparatus according to any one of the first to fourth aspects, the image density of the image data of the original document is preserved even when the image data is filtered. In addition, it is possible to obtain a read image having no sense of incongruity even in the vicinity of the threshold used for removing the background.
[0112]
According to a sixth aspect of the present invention, in the image reading apparatus according to any one of the first to fifth aspects, the image processing for the image data and the image processing for the detection data can be made exactly the same content, The image density of the image data can be stored more accurately.
[0113]
Also, It becomes easy to process the image data and the detection data by the same image processing means.
[0114]
Claim 7 The invention described in claim 1 In the image reading apparatus described in 1), it is possible to simplify the system by sharing an algorithm in the image processing unit and the background removal unit.
[0115]
Also, Even if small detection data is included in the image data, the detection data can be accurately maintained without being affected by the filtering process.
[0116]
Claim 8 The invention described in claim 1 In the image reading apparatus described in (1), even if the detection data is included in the image data, the detection data can be accurately maintained without being affected by the filtering process.
[0117]
Claim 9 The invention described in claim 1 8 In the image reading apparatus according to any one of the above, it is possible to store image data after image processing and selectively perform background removal or not.
[0118]
Claim 10 The invention described in claim 1 9 The same operations and effects as described in any one of the above can be achieved.
[0119]
Claim 11 In the invention described in, since the same image processing is applied to both the image data and the detection data, it is possible to remove the background of the image data with the detection data after this processing, and the image density of the image data of the original is kept preserved. In addition, it is possible to obtain a read image having no sense of incongruity even in the vicinity of the threshold used for removing the background.
[0120]
Claim 12 The invention described in claim 11 In the image data processing method described in the above, even if γ conversion is performed on the image data, it is possible to obtain a read image that retains the image density of the image data of the original and that does not feel uncomfortable even near the threshold used for background removal. it can.
[0121]
Claim 13 The invention described in claim 12 In the image data processing method described in the above, the manufacturing cost can be reduced by sharing the γ conversion function of the background removal process and the γ conversion function of the first image processing process.
[0122]
Claim 14 The invention described in claim 11 ~ 13 In the image data processing method described in any one of the above, even if MTF correction is performed on the image data, the image density of the image data of the original document is preserved, and reading is not uncomfortable even in the vicinity of the threshold used for background removal. An image can be obtained.
[0123]
Claim 15 The invention described in claim 11 ~ 14 In the image data processing method according to any one of the above, even if the image data is filtered, the image density of the image data of the original is kept and the reading is not uncomfortable even near the threshold used for background removal. An image can be obtained.
[0124]
Claim 16 The invention described in claim 11 ~ 15 In the image data processing method according to any one of the above, the image processing for the image data and the image processing for the detection data can be made to have exactly the same contents, and the image density of the image data of the document can be stored more accurately. be able to.
[0125]
Also, It becomes easy to process the image data and the detection data by the same image processing means.
[0126]
Claim 17 The invention described in claim 11 In the image data processing method described in 1), it is possible to simplify the system by sharing an algorithm in the image processing step and the background removal step.
[0127]
Also, Even if small detection data is included in the image data, the detection data can be accurately maintained without being affected by the filtering process.
[0128]
Claim 18 The invention described in claim 11 ~ 17 In the image data processing method according to any one of the above, the detection data can be accurately maintained without being affected by the filter processing even if the detection data is included in the image data.
[0129]
Claim 19 The invention described in claim 11 ~ 18 In the image data processing method described in any one of the above, the image data after the image processing can be stored, and the background can be selectively removed or not.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of a copying machine according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing electrical connection of a control system of the copying machine.
FIG. 3 is a block diagram of a circuit that performs signal processing of an image scanner of the copying machine.
FIG. 4 is a block diagram of a circuit of a background detection unit of the image scanner.
FIG. 5 is a timing chart of each signal of the image scanner.
FIG. 6 is a block diagram of a circuit of a background removal unit of the image scanner.
FIG. 7 is an explanatory diagram illustrating background removal processing of the image scanner.
FIG. 8 is a flowchart illustrating a procedure of the signal processing.
FIG. 9 is a block diagram of a circuit of a background detection unit used in an image scanner of a copying machine according to Embodiment 2 of the present invention.
FIG. 10 is a block diagram of a circuit of the image scanner background removal unit.
FIG. 11 is a timing chart of each signal of the image scanner.
FIG. 12 is an explanatory diagram illustrating a problem of the invention.
[Explanation of symbols]
1 Image forming device
2 Image reader
13 Photoelectric conversion element
32 input devices
50 Synthesis means, gate signal generation means
51 First and second image processing means
52 Background removal means
53 Gate signal specifying means
58 Storage device

Claims (19)

Reading means for reading an image of a document;
A background detection means for detecting the background level of the original from the image data of the read original;
Appends the detection data of the background level in the respective lines output from said background detecting means at the beginning of the effective image data of the image data of the next line, the output together with data indicating the location of the detection data該地skin level Additional means to
Image processing means for performing one or more types of image processing on the image data to which the background level detection data is added;
Based on the data indicating the presence position of the detection data of the background level, the detection data indicating the background level is obtained from the image data after image processing output from the image processing means, and the detection data indicating the background level and the A background removal means for removing the background of the image data output from the image processing means based on the image data after the image processing output from the image processing means;
An image reading apparatus comprising:   The image reading apparatus according to claim 1, wherein one type of the image processing is γ conversion. There are multiple types of image processing,
The image reading apparatus according to claim 2, wherein the image processing unit performs the γ conversion last among the plurality of types of image processing. The image reading apparatus according to claim 1, wherein one type of the image processing is MTF correction. The image reading apparatus according to claim 1, wherein one type of the image processing is filter processing. The image reading apparatus according to claim 1, wherein the image processing unit is the same image processing unit that performs the image processing on the background level detection data and image data. The adding means generates a gate signal for specifying the detection data of the background level included in the image data when adding the detection data of the background level to the image data;
The image reading apparatus according to claim 1 , wherein the background removal means specifies and extracts the background level detection data included in the image data to which the background level detection data is added based on the gate signal. . One type of image processing is filter processing,
The image reading apparatus according to claim 1 , wherein the adding means adds the detection data to an image valid period portion of the image data, and the background level is equal to or larger than a size of a filter matrix used for the filtering process. . A storage device for storing the image data after the image processing;
An input device that accepts the selection of the presence or absence of background removal for the image data;
When the execution of the background removal is selected, the image data stored in the storage device is the target of the background removal by the background removal means, and when the execution of the background removal is not selected, the storage device Selecting means for not subjecting the image data stored in the background removal means by the background removal means;
The image reading apparatus according to claim 1, further comprising: An image reading apparatus according to any one of claims 1 to 9 , comprising:
An image forming apparatus that forms an image on a sheet based on image data read by the image reading apparatus. A background detection step of detecting the background level of the document from the image data of the read document;
The detected detection data of the background level in each line was, appends to the beginning portion of the effective image data of the image data of the next line, and the additional step of outputting together with data indicating the location of the detection data該地skin level ,
An image processing step of performing one or more types of image processing on the image data to which the detection data of the background level is added;
A background level detection step for obtaining detection data indicating a background level from image data after image processing obtained by the image processing step based on data indicating the presence position of the detection data;
Background removal for removing the background of the image data obtained by the image processing step based on the detection data indicating the background level obtained by the background level detection step and the image data after the image processing obtained by the image processing step. An image data processing method comprising the steps of: The image data processing method according to claim 11 , wherein one type of the image processing is γ conversion. There are multiple types of image processing,
The image data processing method according to claim 12 , wherein in the image processing step, the γ conversion is performed last among the plurality of types of image processing. The image data processing method according to claim 11 , wherein one type of the image processing is MTF correction. 15. The image data processing method according to claim 11 , wherein one type of the image processing is filter processing. The image data processing method according to claim 11 , wherein the image processing step is performed collectively by performing the image processing on the background level detection data and the image data. In the adding step, when adding the background level detection data to the image data, a gate signal for specifying the background level detection data included in the image data is generated,
12. The image data according to claim 11 , wherein in the background level detection step, the background level detection data included in the image data to which the background level detection data is added is specified and extracted based on the gate signal. Processing method. One type of image processing is filter processing,
The image data processing according to claim 11 , wherein the adding step adds the detection data to an image valid period portion of the image data, and the background level is equal to or larger than a size of a filter matrix used for the filter processing. Method. A storage step of storing the image data after the image processing in a storage device;
An accepting step for accepting selection of the presence or absence of background removal for the image data;
When the execution of the background removal is selected, the image data stored in the storage device is the target of the background removal by the background removal step, and when the execution of the background removal is not selected, the storage device A selection step that does not subject the image data stored in the background removal step to the background removal step,
The image data processing method according to claim 11 , comprising:

Images