JP2004349858A - Image processor and document duplicating apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately remove the ground of a document even if the document size can not be detected in advance. <P>SOLUTION: If a document size detection part 1802 can not detect the size of the document placed on a reader part in advance, the document is read to the maximum size and converted into image data by an image signal generation part 180. A histogram generation part 1803 when generating a histogram of a luminance distribution according to the above converted image data, is informed of the document size detected while the document is read and generates the histogram to the size. Consequently, the ground level is judged from a histogram of a part which is included in the image data and not a document area to remove the ground. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００７１】
上式において、Ｒ、Ｇ、Ｂが入力、Ｘ、Ｙ、Ｚが出力、ａ１１、ａ１２、ａ１３、ａ２１、ａ２２、ａ２３、ａ３１、ａ３２、ａ３３、ｂ１、ｂ２、ｂ３、ｃ１、ｃ２、ｃ３がそれぞれ係数である。
【００７２】
上式の演算によって、例えばＲＧＢ色空間からＹｕｖ色空間への変換など、各種の色空間変換を行うことができる。
【００７３】
次に、マトリックス演算後のデータに対して、ＬＵＴ８０４による変換を行う。これによって、非線形の変換をも行うことができる。当然、スルーのテーブルを設定することにより、実質的にＬＵＴ変換を行わないこともできる。
【００７４】
その後、色空間変換部８０３は色空間変換処理された画像データをバスコントローラ１１３に転送する。
【００７５】
色空間変換処理された画像データを受け取ったバスコントローラ１１３は、ＤＲＡＭ１１６もしくはＩ／Ｆ上の各デバイスにデータを転送する。
【００７６】
＜画像二値化部の説明＞
以下に画像二値化部８０５における処理手順を示す。Ｉ／Ｆ１３７を介して、ＣＰＵ１１２からバスコントローラ１１３に二値化制御のための設定を行う。この設定によりバスコントローラ１１３は画像二値化部８０５に対して二値化処理に必要な設定（変換方法に応じた各種パラメータ等）を行う。必要な設定を行った後に、再度ＣＰＵ１１２からバスコントローラ１１３に対して画像データ転送の許可を行う。この許可に従い、バスコントローラ１１３はＤＲＡＭ１１６もしくは各Ｉ／Ｆを介して接続されているデバイスから画像データの転送を開始する。
【００７７】
画像二値化部８０５は、受け取った画像データに対して二値化処理を施す。本実施形態では、二値化の手法としては、画像データを所定の閾値と比較して単純に二値化するものとする。もちろん、ディザ法、誤差拡散法、誤差拡散法を改良したものなど、いずれの手法によってもかまわない。
【００７８】
その後、画像二値化部８０５は二値化処理された画像データをバスコントローラ１１３に転送する。二値化処理された画像データを受け取ったバスコントローラ１１３は、ＤＲＡＭ１１６もしくはＩ／Ｆ上の各デバイスにデータを転送する。
【００７９】
＜ＰＤＬ画像出力時のシーケンス＞
図１１は、本実施形態におけるＰＤＬ画像出力の手順を示すフローチャートである。なお、図中のＳ１１０１〜Ｓ１１０９は各ステップを示す。
【００８０】
ＰＤＬ画像を出力する場合、Ｓ１１０１では、ＰＣ４０１上でユーザーが当該ＰＤＬ画像出力ジョブのプリント設定を行う。プリント設定内容は、部数、用紙サイズ、片面／両面、ページ出力順序、ソート出力、ステイプル止めの有無等である。ここで、タブシート印刷を実行する場合、タブシートモードを設定する。
【００８１】
Ｓ１１０２では、ＰＣ４０１上で印刷指示を与え、それと共にＰＣ４０１上にインストールされているドライバソフトウェアが、印刷対象となるＰＣ４０１上のコードデータをいわゆるＰＤＬデータに変換して、Ｓ１１０１で設定したプリント設定パラメータとともに、本画像入出力装置の制御装置１１０に、ネットワーク４００を介してＰＤＬデータを転送する。
【００８２】
Ｓ１１０３では、制御装置１１０のメインコントローラ１１１のＣＰＵ１１２が、コネクタ１２２およびネットワークコントローラ１２１を介して転送されたＰＤＬデータを前記プリント設定パラメータに基づいて、画像データに展開（ラスタライズ）する。画像データの展開は、ＤＲＡＭ１１６上に行われる。画像データの展開が完了するとＳ１１０４へ進む。
【００８３】
Ｓ１１０４では、メインコントローラ１１１がＤＲＡＭ１１６上に展開された画像データを、グラフィックプロセサ１３５に転送する。
【００８４】
Ｓ１１０５では、グラフィックプロセサ１３５が、前記プリント設定パラメータとは独立に、画像処理を行う。例えば、前記プリント設定パラメータで指定された用紙サイズがＡ４であるにもかかわらず、プリンタ部３００の給紙ユニット３６０にはＡ４Ｒ用紙しかない場合には、グラフィックプロセサ１３５で画像を９０度回転することによって、出力用紙にあわせた画像出力を行うことができる。画像データの画像処理が完了するとＳ１１０６へ進む。
【００８５】
Ｓ１１０６では、グラフィックプロセサ１３５がメインコントローラ１１１へ画像処理後の画像データを転送する。メインコントローラ１１１は転送されてきた画像データをＤＲＡＭ１１６上に記憶する。
【００８６】
Ｓ１１０７では、ステップＳ１１０１での設定に基づき、印刷モードがタブシートモードに設定されているか否かを判断する。
【００８７】
ステップＳ１１０７で、タブシートモードでないと判断された場合、ステップＳ１１０８へ進み、Ｓ１１０８では、メインコントローラ１１１はプリンタＩ／Ｆ１４５およびコネクタ１４７を介して、プリンタ部３００を制御しつつ、適切なタイミングでＤＲＡＭ１１６上の画像データを、プリンタ部３００へと転送する。
【００８８】
ステップＳ１１０９では、制御装置１１０が、プリンタ部３００を制御して画像データをプリント出力する。画像データの転送が完了すると、すなわち当該ＰＤＬジョブが終了すると、プリント出力を終了する。
【００８９】
一方、ステップＳ１１０７で、タブシートモードであると判断された場合、ステップ１１１０に進み、図１７を用いてタブシートイメージをＤＲＡＭ上に形成する。
【００９０】
そして、ステップＳ１１０８へ進み、ＤＲＡＭからプリンタへ生成した画像データを転送し、ステップＳ１１０９において、予め設定されているタブシートに画像をプリントし、処理を終了する。
【００９１】
＜コピー画像出力時のシーケンス＞
図１２は、本実施形態におけるコピー画像出力の手順を示すフローチャートである。なお、図中のＳ１２０１〜Ｓ１２０８は各ステップを示す。
【００９２】
コピー画像を出力する場合、Ｓ１２０１では、操作部１５０上でユーザーが当該コピー画像出力ジョブのコピー設定を行う。コピー設定内容は、部数、用紙サイズ、片面／両面、拡大／縮小率、ソート出力、ステイプル止めの有無等である。なお、ここで、タブシート印刷を実行する場合、タブシートモードを設定する。
【００９３】
Ｓ１２０２では、操作部１５０上でコピー開始指示を与えると、制御装置１１０のメインコントローラ１１１はスキャナＩ／Ｆ１４０およびコネクタ１４２を介してリーダー部２００を制御し、原稿の画像データの読み込み動作を行う。まず、原稿給送ユニット２５０は、載置された原稿を１枚ずつプラテンガラス２１１上へ給送し、その際同時に原稿のサイズを検知する。検知された原稿のサイズに基づいて原稿を露光走査することにより、画像データを読み取るわけである。読み取られた画像データはＤＲＡＭ１１６上に記憶される。従来のコピー機では、前記コピー設定の拡大／縮小率の設定に応じて、すなわち副走査方向の変倍率に応じて光学ユニット２１３の移動速度を変化させることにより副走査方向の変倍処理を実現していた。しかしながら、本実施形態では、前記コピー設定の拡大／縮小率の設定にかかわらず、必ず等倍（１００％）で画像データを読み取り、変倍処理については、主走査方向、副走査方向ともに、後述するグラフィックプロセサ１３５によって行うものとする。
【００９４】
Ｓ１２０３では、メインコントローラ１１１がＤＲＡＭ１１６上の画像データを、グラフィックプロセサ１３５に転送する。
【００９５】
Ｓ１２０４では、グラフィックプロセサ１３５が、前記コピー設定パラメータに基づいて画像処理を行う。例えば、拡大４００％の設定がなされているときには、グラフィックプロセサ１３５内のモジュールである画像変倍部を用いて主走査方向、副走査方向、双方への変倍処理を行う。画像データの画像処理が完了するとＳ１２０５へ進む。
【００９６】
Ｓ１２０５では、グラフィックプロセサ１３５がメインコントローラ１１１へ画像処理後の画像データを転送する。メインコントローラ１１１は転送されてきた画像データをＤＲＡＭ１１６上に記憶する。
【００９７】
Ｓ１２０６では、ステップＳ１２０１での設定に基づき、印刷モードがタブシートモードに設定されているか否かを判断する。
【００９８】
ステップＳ１２０６で、タブシートモードでないと判断された場合、ステップＳ１２０７へ進み、Ｓ１２０７では、メインコントローラ１１１はプリンタＩ／Ｆ１４５およびコネクタ１４７を介して、プリンタ部３００を制御しつつ、適切なタイミングでＤＲＡＭ１１６上の画像データを、プリンタ部３００へと転送する。
【００９９】
Ｓ１２０８では、制御装置１１０が、プリンタ部３００を制御して画像データをプリント出力する。画像データの転送が完了すると、すなわち当該コピージョブが終了すると、プリント出力を終了する。
【０１００】
一方、ステップＳ１２０６で、タブシートモードであると判断された場合、ステップ１１１０に進み、図１７を用いてタブシートイメージをＤＲＡＭ上に形成する。
【０１０１】
そして、ステップＳ１２０８へ進み、ＤＲＡＭからプリンタへ生成した画像データを転送し、ステップＳ１２０８において、予め設定されているタブシートに画像をプリントし、処理を終了する。
【０１０２】
＜画像パケット構造の実施形態＞
図１３は、本実施形態のパケット構造を示す図である。１パケットは３２×３２画素の１タイル分の画像データを収容するデータ本体１０と、ヘッダ１２からなる。ヘッダ１２は、パケットのシリアル番号を示すパケットＩＤ１４、データ本体１０に収容される画像データが圧縮されているか否かを示す圧縮フラグ１６、及び、データ本体１０に収容される画像データ量を示す画像データ長１８を具備する。本実施形態では、パケットＩＤ１４は１バイト、圧縮フラグ１６は１ビット、データ長１８は２バイトである。パケットヘッダには上記以外に、圧縮方式を示すフラグ、像域判定のフラグ、ＡＣＳ判定の結果、色空間情報など、任意の情報を含めることができる。
【０１０３】
図１４は、１ページの画像データを３２画素×３２画素からなるタイルに分割した様子を示す。１タイルの画像データが、図１４に示すように１つのパケットに収容される。１タイルは３２×３２画素でなくても良く、例えば、６４×６４画素でも良いし、更には、正方形でなく矩形などでも良い。１タイルが３２画素×３２画素の場合、例えば、Ａ４を６００ｄｐｉの解像度では、タイル数は、２２０×１５６＝３４３２０になり、Ａ３を１２００ｄｐｉの解像度では、タイル数は４４０×６２４＝２７４，５６０になる。
【０１０４】
本実施形態では、画像データを圧縮する場合に、１ページ分をまとめて圧縮するのではなく、パケット単位、即ち、タイル単位で画像データを圧縮するか否かを決定する。圧縮後のデータ量が圧縮前のデータ量よりも多くなる場合には、圧縮しない。
【０１０５】
本実施形態のパケットは、ヘッダ１２に圧縮フラグ１６を具備するので、データ本体１０に圧縮画像データが収容されたか非圧縮の画像データが収容されたかを圧縮フラグ１６で識別できる。圧縮画像データをデータ本体１０に収容した場合には、圧縮フラグに’１’をセットし、データ本体１０に非圧縮画像データを収容した場合には、圧縮フラグに’０’をセットする。１ページ中には、圧縮画像データを持つパケットと、非圧縮画像データを持つパケットが混在する。
【０１０６】
例えば、１ページのプレーンな画像データがあり、これを圧縮する場合に、本実施形態の画像データフォーマットの形式を採用したとする。先ず、ページ画像データを図１４に示すようにタイルに分割する。このタイル毎の画像データを、例えばＪＰＥＧ方式などで圧縮する。圧縮方法は、別の方法でも良い。圧縮の結果、元の画像データ量よりもデータ量が少なくなったときには、圧縮画像データをパケットのデータ本体１０に収容し、そのデータ量をヘッダ１２のデータ長１８に格納し、圧縮フラグ１６に’１’をセットする。逆に、圧縮の結果、元の画像データ量よりもデータ量が多くなったときには、非圧縮の画像データをパケットのデータ本体１０に収容し、そのデータ量をヘッダ１２のデータ長１８に格納し、圧縮フラグ１６に’０’をセットする。
【０１０７】
このようにして、各タイルについてデータの圧縮とパケット化を繰り返し、１ページのデータを作成する。このようにして出来た１ページ分のデータは、各パケットのデータ本体１０について元の画像データ量を超えないことを保証できる。ヘッダ１２のデータ量は固定（４バイト）なので、１ページの総データ量の最大値は、（１タイルの非圧縮の画像データ量＋ヘッダのデータ量４バイト）×（１ページのタイル数）で計算される。
【０１０８】
圧縮／非圧縮のパケットが混在しているページ画像データを伸長して非圧縮の画像データを復元する場合には、各パケットのヘッダ１２の圧縮フラグ１６を参照し、それが’１’であるパケットに収容されるデータのみを伸長すればよい。
【０１０９】
このように、本実施形態では、１タイル分の非圧縮画像データを一時保持すれば済むので、そのためのメモリ容量は小さくて済む。そのタイルの画像データの圧縮が終了し、そのタイルのパケットを生成した後は、そのタイルの画像データを消去しても構わない。つまり、１タイルの画像データを圧縮しパケット化する毎に、そのタイルの原画像データを消去できる。これにより、圧縮の際に必要となるメモリの作業領域は、１タイル分の画像データの容量があれば良いことになる。
【０１１０】
図１５は、本実施形態におけるパケットデータ生成に係る構成を説明するブロック図である。メモリ１１６を除く図１５の処理ブロックは、図４に示すメインコントローラ１１１に含まれる。１１２はＣＰＵ、２２はメモリ制御回路であり、１１６はメモリ（ＤＲＡＭ）である。３４は、ＣＰＵ２０、メモリ制御回路２２及びＤＭＡ制御回路３２を接続するシステムバスである。
【０１１１】
２６は処理すべき画像データが入力する入力端子、２８は入力端子２６に入力した画像データを、図１３及び図１４を参照して説明したパケットに成形するパケット生成回路である。パケット生成回路２８は、タイル単位で画像データを圧縮する画像圧縮回路を具備する。３０は、画像圧縮前後の画像データを一時記憶するバッファである。３２は、パケット生成回路２８の出力パケットをＤＭＡ（Ｄｉｒｅｃｔ Ｍｅｍｏｒｙ Ａｃｃｅｓｓ）方式で、メモリ制御回路２２を介してメモリ２４に転送するＤＭＡ制御回路である。
【０１１２】
基本的なデータの流れを説明する。スキャナＩ／Ｆ１４０等から入力された画像データが、３２画素×３２画素のタイル単位で入力端子２６に入力する。パケット生成回路２８は、タイル単位で画像データを圧縮し、非圧縮画像データと圧縮画像データとを比較し、少ないデータ量の方をデータ本体１０に収容し、ヘッダ１２の圧縮フラグ１６に’０’又は’１’をセットし、図１３に示すパケットのフォーマットでＤＭＡ制御回路３２に出力する。ＤＭＡ制御回路３２は、パケット生成回路２８からのパケット・データを、システム・バス３４及びメモリ制御回路２２を介してメモリ２４に書き込む。
【０１１３】
図１６は、パケット生成回路２８の概略構成ブロック図を示す。圧縮回路４０は、入力端子２６からのタイル単位の画像データをバッファ３０に格納すると共に圧縮して圧縮画像データもバッファ３０に格納し、非圧縮画像データと圧縮画像データとを比較して、少ないデータ量の方を出力する。すなわち、圧縮後の画像データ量が圧縮前の画像データ量よりも少ない場合には、圧縮回路４０は、圧縮画像データをマージ回路４４に出力すると共に、ヘッダ生成回路４２に、マージ回路４４に出力したデータが圧縮データであること及びそのデータ量を通知する。逆に、圧縮後の画像データ量が圧縮前の画像データ量よりも多い場合には、圧縮回路４０は、圧縮前の画像データをマージ回路４４に出力すると共に、ヘッダ生成回路４２に、マージ回路４４に出力したデータが非圧縮データであること及びそのデータ量を通知する。
【０１１４】
ヘッダ生成回路４２は、パケットＩＤ１４を順にインクリメントし、画像データ長１８にデータ量をセットし、圧縮フラグ１６については、圧縮回路４０がマージ回路４４に非圧縮データを出力するときには、’０’をセットし、圧縮回路４０がマージ回路４４に圧縮画像データを出力するときには、’１’をセットする。そして、ヘッダ生成回路４２は、このように生成したヘッダ情報をマージ回路４４に出力する。
【０１１５】
マージ回路４４は、ヘッダ生成回路４２からのヘッダと圧縮回路４０からのデータとをマージして、図１３に示すフォーマットのパケットを生成する。生成されたパケットは、ＤＭＡ制御回路３２に送られる。
【０１１６】
ＤＭＡ制御回路３２は、パケットデータを格納するアドレスを示すパケットアドレスレジスタを具備する。ＤＭＡ制御回路３２は、パケット生成回路２８（のマージ回路４４）からのパケットを、パケットアドレスレジスタで示されるメモリ１１６のアドレスへ書き込む。パケットアドレスレジスタは、記憶値をパケット容量分だけ加算して更新する。その後、ＤＭＡ制御回路３２は、次のパケットをパケット生成回路２８から受け取る。
【０１１７】
図１７は、パケットデータとパケットテーブルの関係を示している。図中、１７００は各パケットのメモリ上での開始アドレス１７０１を示すパケットテーブル、１７０２はリピートフラグであり、ひとつ前のパケットとデータが同じ場合にフラグがオンになり、異なる場合にはオフに設定される。また、１７１０はメモリに格納されているパケットデータ領域であり、図示の如く模式的に示した。パケット１７１１とテーブル上のアドレスとは１対１で対応しており、パケット１７１２とテーブル上のアドレスとは、リピートフラグを用いることにより１対２で対応している。
【０１１８】
＜下地レベル判定の実施形態＞
図１８は下地レベル判定を示したブロック図である。図１８において、画像信号生成部１８０１はリーダ部２００のリーダ画像処理部２２２に、原稿サイズ検知部１８０２は、リーダ部２００のサイズセンサ２９０に相当する。なおサイズセンサ２９０の出力信号をメインコントローラ１１１等により原稿サイズに変換する場合には、メインコントローラ部１１１等による当該処理を含む。また、ヒストグラム生成部１８０３及びヒストグラム生成領域変更部１８０４は、スキャナＩ／Ｆ１４０のヒストグラムカウント部５０４に含まれる。また、下地除去処理部１８０５及び下地レベル判定部１８０６は、プリンタＩ／Ｆ部１４５の下地とばし部７０６に含まれる。
【０１１９】
原稿がフィーダーに引き込まれ、ＣＣＤ・ＣＩＳなどの読取装置により読み取られ始めると、画像信号生成部１８０１はＲＧＢ各輝度信号に変換し、後段へデータ送り出す。この輝度信号からヒストグラム生成手段１８０３は、一定のあるいは指定されたサンプリングピッチで画素を抽出し、輝度レベルをカウントすることでＲＧＢ各色のヒストグラムを生成する。
【０１２０】
スキャン開始までに原稿サイズがわかっていない場合、画像信号生成部１８０１以降の処理は、想定される最大サイズ（幅は特定可能であるから、その幅について定められた最大サイズ）の画像の長さを想定して処理を行うことが一般的である。例えば、この想定される最大サイズは、原稿サイズ検知部１８０２により原稿読み取り前に予め検知できる最大の原稿サイズよりも大きいサイズが設定される。画像信号生成部１８０１は、原稿サイズが実際には最大長で無い場合であっても、すでに後段（すなわち画像データの送り先）の画像処理デバイス（グラフィックプロセッサ等を含むコントローラ部１１０）に画像サイズなどの処理対象とする領域が渡されて設定されてしまっているため、それに合わせて最大長で画像信号を生成する。
【０１２１】
ここで、画像信号生成途中で原稿サイズ検知部１８０２が検知した信号に基づいてリーダ部２００あるいはメインコントローラ部１１０が決定した原稿サイズ情報が、コントローラ部１１０を介してあるいは原稿サイズ部１８０２から直接的に、スキャナＩＦ部１４５に含まれるヒストグラムカウント部６１３のヒストグラム生成領域変更部１８０４に伝えられる。ヒストグラム生成領域変更部１８０４は、ヒストグラム生成部１８０３がサンプリングする画像データの領域を原稿サイズに変更する。たとえば、コントローラ部１１０あるいはリーダＩＦ部１４０から受信した実際の原稿サイズおよびスキャンされたサイズが、ともに「幅（ドット）×長さ（ドット）」という形式で表されているとする。この場合には、幅及び長さ共に、ヒストグラムの作成の対象となる画像データのサイズを、元はスキャンされたサイズとなっているところを、原稿サイズに置換する。ただし、原稿に相当する画像データは、スキャンされて読み取られた画像データの先頭など、スキャンされた画像データのうちの一定の位置から開始されるものとする。
【０１２２】
原稿がスキャンされた後、下地レベル判定部１８０６はヒストグラム生成部１８０３により原稿領域によりサンプリングされたヒストグラムから下地レベルを判定し、下地除去処理部１８０５へ下地を飛ばす係数を設定し、下地除去処理部１８０５は画像データの下地を飛ばす処理を行う。
【０１２３】
たとえば、下地レベルは、各色成分について最も分布している度数が多い輝度とし、全色成分についてその付近（一定の誤差範囲内）の輝度を有する画素を最高輝度（白色）の画素に置換することで、下地をすべて白色に置換して下地とばしする処理が考えられる。またたとえば、下地の濃度が高い場合には、下地に描かれたオブジェクトの方が濃度が低い場合もあり得るので、そのような場合に下地を白色に置換するとオブジェクトの視認性がむしろ悪化することもあり得る。そこで、置換は、下地が一定濃度以下（一定輝度以上）の場合に限って行うことも考えられる。
【０１２４】
図２１は、図１８に示すヒストグラムカウント部６１３により実行される処理手順を示す。スキャナＩＦ部１４０がたとえばプロセッサとメモリとを備えるコンピュータにより制御されている場合、図２１の手順すなわちヒストグラムカウント部６１３は、そのプロセッサにより図２１の手順のプログラムを実行することで実現される。この場合、ヒストグラムの各色成分及び各輝度毎の度数カウンタは、そのメモリに確保される。
【０１２５】
まず、ヒストグラムを生成する対象となる領域サイズを、スキャンされたサイズから、リーダ部２００から（あるいは原稿サイズをメインコントローラ１１１で決定する場合にはメインコントローラ１１１から）受信した原稿サイズに置換する（Ｓ２１０１）。これにより、実際の原稿サイズにしたがってヒストグラムを生成できる。
【０１２６】
そして、設定された領域内の注目画素について、その注目画素の各色成分の輝度に相当する度数カウンタに１ずつ加算する（Ｓ２１０２）。また、ＭＤ成分についても輝度を求めて相当する輝度の度数に１加算する。
【０１２７】
そして、設定された領域内の全画素についてカウントしたか判定し（Ｓ２１０３）、していなければ注目画素を設定された領域内における次の画素に移してヒストグラムの生成処理を続ける。
【０１２８】
この手順で生成されたヒストグラムは、メインコントローラ１１１を介して、あるいは直接的にプリンタＩ／Ｆ部１４５に送信され、下地とばし部７０６による下地とばし処理に用いられる。もちろんヒストグラムその物ではなく、下地レベル判定部１９０７をメインコントローラ１１１において実現し、そこで決定された下地レベルをプリンタＩ／Ｆに送信して下色除去処理を行わせることもできる。
【０１２９】
以上の構成及び処理によって原稿サイズが確定した時点でヒストグラムを算出する領域を変更することができ、原稿に含まれない領域の画像データについてはヒストグラム生成の対象としないために、原稿の下地レベルを高精度で検出することが可能である。
【０１３０】
［第２実施形態］
次に第２実施形態を示す。第２実施形態では、図１〜図１７の構成は第１実施形態と共通である。そして図１８及び図２１に代えて、図１９及び図２２の構成を備えている。
【０１３１】
図１９は第２実施形態の場合の下地レベル判定を示したブロック図である。図１９において、画像信号生成部１９０１および原稿エリア外マスク部１９０３はリーダ部２００のリーダ画像処理部２２２に、原稿サイズ検知部１９０２は、リーダ部２００のサイズセンサ２９０に相当する。なおサイズセンサ２９０の出力信号をメインコントローラ１１１等により原稿サイズに変換する場合には、メインコントローラ部１１１等による当該処理を含む。
【０１３２】
また、ヒストグラム生成部１９０４は、スキャナＩ／Ｆ１４０のヒストグラムカウント部５０４に含まれる。また、マスク領域除去部１９０５は、メインコントローラ１１１により実現される。
【０１３３】
また、下地除去処理部１９０６及び下地レベル判定部１８０７は、プリンタＩ／Ｆ部１４５の下地とばし部７０６に含まれる。
【０１３４】
原稿がフィーダーに引き込まれ、ＣＣＤ・ＣＩＳなどの読取装置により読み取られ始めると、画像信号生成部１９０１はＲＧＢ各輝度信号に変換し、後段へデータ送り出す。この輝度信号からヒストグラム生成部１９０４は任意のサンプリングピッチで画素を抽出し、輝度レベルをカウントすることでＲＧＢ各色のヒストグラムを生成する。
【０１３５】
スキャン開始までに原稿サイズがわかっていない場合、画像信号生成部１９０１以降の処理は、想定される最大サイズの画像の長さを想定して処理を行うことが一般的である。画像信号生成部１９０１は、原稿サイズが最大長で無い場合も、すでに後段の画処理デバイス等に画像サイズなどの領域が設定されてしまっているため、最大長で画像信号を生成することが考えられる。
【０１３６】
すなわち、このような場合、リーダ部２００においては原稿をスキャンし終えた時点で原稿サイズ情報を獲得できる。ただし、すでに最大長の原稿を読み取るものと後段のコントローラ部１１０にはそのスキャンするサイズを通知しているために、画像データは通知しておいたサイズでコントローラ部１１０に送信する必要がある。そこで、原稿に相当する領域以外の部分については、原稿エリア外マスク部１９０３により一定の輝度の画素データ、たとえば最高輝度の画素データを充填（マスク）する。この一定輝度の画素データを充填した領域をマスク領域と呼ぶ。
【０１３７】
ここで、原稿サイズ検知部１９０２が確定する原稿サイズがヒストグラムカウント部６１３に届くタイミングが、ヒストグラム生成部１９０４が原稿サイズ分のデータを処理した後の場合、第１実施形態のように原稿に相当する領域についてのみヒストグラムを生成することはできない。そこで、本実施形態では、スキャナＩ／Ｆ１４５のヒストグラムカウント部６１３において、いったん、リーダ部２００から受信した画像データ全体についてヒストグラムのサンプリングを行う。その後、マスク領域除去部１９０５により、原稿サイズ検知部１９３２により受信した原稿サイズをスキャンされたサイズから除いた領域、すなわちマスク領域のサイズ（たとえば縦方向の画素数×横方向の画素数）を求める。そして、ヒストグラム生成部１９０４が生成したヒストグラムから、原稿エリア外マスク部１９０３により充填された一定の輝度の画素データ分の度数（すなわち充填された画素数）を、各色成分について差し引く。こうすることで、原稿エリアのみのヒストグラムを生成しなおす。
【０１３８】
この原稿エリアのみのヒストグラムから下地レベル判定部１９０７は下地レベルを判定し、下地除去処理部１９０６へ下地を飛ばす係数を設定し、下地除去処理部１９０６は画像データの下地を飛ばす処理を行う。
【０１３９】
ここで図２０は、図１９で説明した場合の詳細を示した図である。
【０１４０】
スキャン画像２０００は、原稿領域２００１と、原稿エリア外マスク部１９０３により充填された特定輝度２５５（図２０の符号２００５の部分）を有するマスク領域２００２からなる。一方、原稿に相当する領域は、輝度１５０の領域２００３と、輝度２５５の領域２００４からなっていたとする。この場合、ヒストグラム生成部１９０４により生成されるヒストグラムはヒストグラム２０１０に示すように、マスク領域を含む画素値の分布を示すものになる。
【０１４１】
この図２０のヒストグラム２０１０の横軸は輝度（０−２５５）を示し、縦軸はその輝度の画素をカウントした度数である。ここで、スキャン画像２０００では、領域２００４及び領域２００５の２箇所において輝度２５５の領域が広いため、輝度２５５のカウント数２００７は、領域２００３の輝度１５０のカウント数２００６を超えている。このヒストグラム２０１０から下地レベルを判定すると、輝度２５５が下地となり、実質下地飛ばしは行われないことになる。
【０１４２】
ここで、マスク領域除去部１９０５により領域２００５の取りうる分のカウント数を輝度２５５のカウント数２００７から差し引くと、ヒストグラム２０１１のようなヒストグラムとなり、輝度１５０のカウント数２００８が輝度２５５のカウント数２００９よりも多くなり、輝度１５０を下地と判断し、下地除去処理部１９０６に輝度１５０を下地として飛ばす設定をすることで、スキャン原稿の下地２００３の色を飛ばして、画像２０１２の様になる。このため、本来の原稿の下地が下地とばし処理によって除去され、下地を除いた文字や写真等のオブジェクトが視認しやすい画像が形成できる。
【０１４３】
図２２は図１９に示すヒストグラムカウント部６１３により実行される処理手順を示す。スキャナＩＦ部１４０がたとえばプロセッサとメモリとを備えるコンピュータにより制御されている場合、図２２の手順すなわちヒストグラムカウント部６１３は、そのプロセッサにより図２１の手順のプログラムを実行することで実現される。この場合、ヒストグラムの各色成分及び各輝度毎の度数カウンタは、そのメモリに確保される。
【０１４４】
まず、ヒストグラムを生成する対象となる領域サイズとして、リーダ部２００から（あるいは原稿サイズをメインコントローラ１１１で決定する場合にはメインコントローラ１１１から）受信した、スキャンされた領域全体のサイズを設定する（Ｓ２２０１）。
【０１４５】
そして、設定された領域内の注目画素について、その注目画素の各色成分の輝度に相当する度数カウンタに１ずつ加算する（Ｓ２２０２）。また、ＭＤ成分についても輝度を求めて相当する輝度の度数に１加算する。
【０１４６】
そして、設定された領域内の全画素についてカウントしたか判定し（Ｓ２２０３）、していなければ注目画素を設定された領域内における次の画素に移してヒストグラムの生成処理を続ける（Ｓ２２０４）。
【０１４７】
この手順で生成されたヒストグラムは、メインコントローラ１１１に送信され、メインコントローラ１１１において、生成されたヒストグラムの内、マスク領域に充填された画素値の度数から、マスク領域の画素数を差し引く（Ｓ２２１１）。この処理は、各色成分について行われる。これにより、原稿に相当する領域のヒストグラムが得られる。ヒストグラムそのものあるいはそれから得られた下地レベルは、直接的にプリンタＩ／Ｆ部１４５に送信され、下地とばし部７０６による下地とばし処理に用いられる。
【０１４８】
なお、マスク領域除去部１９０５による処理は、スキャナＩＦ部１４０により実行することもできる。
【０１４９】
以上の構成及び処理により、原稿サイズが確定した時点ではヒストグラムを算出する領域を変更することが不可能な場合でも、算出されたヒストグラムから原稿以外の無効な画像領域に相当する度数を減算することで、原稿の下地レベルを高精度で検出することが可能である。
【０１５０】
（他の実施形態）
上記実施形態においては、本発明をデジタル複合機において適用した例で説明したが、これに限るものではなく、本発明は、例えば、スキャナでスキャンした画像を送信する場合の、ファクシミリ装置、プリンタ等他の画像形成装置における印刷においても適用可能であることは言うまでも無い。さらに画像形成装置に限らず、例えば、パーソナルコンピュータ上のプリンタドライバや、画像処理ソフトウェアにおいて、本発明を適用してもよい。
【０１５１】
また、本発明は、前述した実施の形態の機能を実現するソフトウェアのプログラムコードを記憶した記憶媒体をシステムあるいは装置に供給し、そのシステムあるいは装置のコンピュータ（またはＣＰＵやＭＰＵ）が記憶媒体（例えば上述した本実施の形態におけるＲＡＭ３１）に格納されたプログラムコードを読み出し実行することによっても、完成されることは言うまでもない。
【０１５２】
この場合、記憶媒体から読み出されたプログラムコード自体が前述した実施形態の機能を実現することになり、そのプログラムコードを記憶した記憶媒体は本発明を構成することになる。プログラムコードを供給するための記憶媒体としては、例えば、フロッピー（登録商標）ディスク、ハードディスク、光ディスク、光磁気ディスク、ＣＤ−ＲＯＭ、ＣＤ−Ｒ、磁気テープ、不揮発性のメモリカード、ＲＯＭを用いることができる。また、コンピュータが読み出したプログラムコードを実行することにより、前述した実施形態の機能が実現されるだけではなく、そのプログラムコードの指示に基づき、コンピュータ上で稼動しているＯＳなどが実際の処理の一部または全部を行い、その処理によって前述した実施形態の機能が実現される場合も含まれることは言うまでもない。
【０１５３】
さらに、記憶媒体から読み出されたプログラムコードが、コンピュータに挿入された機能拡張ボードやコンピュータに接続された機能拡張ユニットに備わるメモリに書きもまれた後、次のプログラムコードの指示に基づき、その拡張機能を拡張ボードや拡張ユニットに備わるＣＰＵなどが処理を行って実際の処理の一部または全部を行い、その処理によって前述した実施形態の機能が実現される場合も含まれることは言うまでもない。
【０１５４】
また、このような記憶媒体を含む装置をネットワーク上に配置させておき、記憶媒体に記憶されたプログラムをネットワークを介して所定の装置へダウンロードし、ダウンロードしたプログラムを実行することによっても、本発明の上記実施形態の機能が実現されることは言うまでもない。
【０１５５】
【発明の効果】
以上説明してきたように、本発明は、原稿サイズが確定した時点でヒストグラムを算出する領域を変更することで、原稿の下地レベルを高精度で検出することが可能である。
【０１５６】
また、原稿サイズが確定した時点ではヒストグラムを算出する領域を変更することが不可能な場合は、算出されたヒストグラムから原稿以外の無効な画像領域文のヒストグラムを減算することで、原稿の下地レベルを高精度で検出することが可能である。
【図面の簡単な説明】
【図１】本実施形態に係る画像入出力システムの全体構成を説明するための図である。
【図２】リーダー部２００及びプリンタ部３００の概観図である。
【図３】リーダー画像処理部２２２の詳細な構成を示すブロック図である。
【図４】制御装置１１０のブロック図である。
【図５】スキャナＩ／Ｆ１４０の画像処理を担う部分の詳細な構成を示すブロック図である。
【図６】ＡＣＳ（オートカラーセレクト）カウント部を説明する図である。
【図７】プリンタＩ／Ｆ１４５の画像処理を担う部分の詳細な構成を示すブロック図である。
【図８】グラフィックプロセサ１３５の詳細な構成を示すブロック図である。
【図９】タイル画像のアドレスを説明するための図である。
【図１０】回転処理を説明するための図である。
【図１１】本実施形態におけるＰＤＬ画像出力の手順を示すフローチャートである。
【図１２】本実施形態におけるコピー画像出力の手順を示すフローチャートである。
【図１３】本実施形態のパケット構造を示す図である。
【図１４】１ページの画像データを３２画素×３２画素からなるタイルに分割した様子を示す図である。
【図１５】本実施形態におけるパケットデータ生成に係る構成を説明するブロック図である。
【図１６】パケット生成回路２８の概略構成を示すブロック図である。
【図１７】パケットデータとパケットテーブルの関係を示す図である。
【図１８】第１実施形態の下地レベル判定方法を示すブロック図である。
【図１９】第２実施形態の下地レベル判定方法を示すブロック図である。
【図２０】第２実施形態の下地レベル判定方法を示す図である。
【図２１】第１実施形態の下地レベル判定手順を示す流れ図である。
【図２２】第２実施形態の下地レベル判定手順を示す流れ図である。
【符号の説明】
１１０ コントローラ
１１２ ＣＰＵ
１１６ ＤＲＡＭ
１３５ グラフィックプロセサ
２００ リーダー装置
３００ プリンタ装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing device, a storage medium, and a program that perform predetermined processing on an input image and output the processed image.
[Prior art]
Generally, in a digital color copying machine, various correction processes are performed on read color image data (RGB), and finally, data of YMC and Bk, which are recording color components, are generated and recorded. Normally, the background of a document is often white, and although this is not usually a problem, the background of a document to be copied is not always white. For example, the base often has a yellow tint.
[0002]
Even when the background is other than white, the digital color copying machine tries to faithfully reproduce the color of the background. However, the information actually required, that is, the object to be copied is not the background but the characters or the like on the original. For this reason, there have been proposed some copying machines in which the background is excluded from the recording (so-called "skip the background") (see Patent Document 1 and the like).
[0003]
In order to perform background skipping, it is necessary to determine the background color of the document. The base portion occupies most of the document. Therefore, a histogram of the color of the image obtained by scanning is created, the level of the background that occupies most of the document is determined, and the background is removed from the scanned image using a process such as non-linear background removal. , Display, transmission, printing, and the like on the UI, the image with the background removed has been output.
[0004]
[Patent Document 1]
JP-A-5-63968
[Patent Document 2]
JP-A-6-152997
[0005]
[Problems to be solved by the invention]
When such background removal is performed, the range of the original for which the histogram is to be created is determined based on the size of the original when the paper size is specified or when the original size is specified or automatically detected before scanning. A document scan size is determined, and a histogram is created only in an appropriate range of scan image data sent from a reading device such as a reader.
[0006]
Here, when the paper size is specified in the automatic paper size selection mode, the original is fed by a feeder (automatic original feeder) like a long original, and an original that cannot be detected immediately is scanned. The document size is determined when the feeder feeds the document to some extent and detects the trailing edge of the document.
[0007]
However, if the original size cannot be detected at the time when the original has moved to the original scan start position, the original scan size is specified by the maximum length of the original assumed by the apparatus and the original is scanned. In such a case, if the actual document size is smaller than the size of the area to be scanned, the histogram generated for the scanned image data is created including invalid image areas other than the actual document. turn into. Therefore, as the document size is smaller than the scan size, the detection accuracy of the background level decreases.
[0008]
The present invention is to solve the above-described problem, and changes the area for calculating the histogram when the document size is determined, or changes the area for calculating the histogram when the document size is determined. If it is not possible, an image processing apparatus, an image processing method, a storage medium, and the like that detect the background level of the document by subtracting the histogram for the invalid image area other than the document from the calculated histogram The purpose is to provide the program.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has the following configuration.
(1) an image processing apparatus, wherein input means reads an original image as an image of a fixed size;
Size detecting means for detecting a document size while reading a document image by the input means,
Histogram creation means for creating a histogram of a luminance distribution according to the size detected by the size detection means, for image data of the fixed size image read by the input means,
A background removal processing unit for removing a background level of the document image from the image data based on the histogram.
(2) An input means for detecting an original size while reading an original image as an image of a fixed size, and filling pixels of a fixed color for image data within the fixed size and outside the original size. When,
Histogram creating means for creating a histogram of the luminance distribution for the image data read by the input means,
Correction means for correcting by subtracting the frequency of a certain color filled by the input means from the histogram,
A background removal processing unit that removes a background level of the document image from the image data based on the histogram corrected by the correction unit.
(3) More preferably, in the image processing apparatus according to (1) or (2), the input unit further includes a preliminary detection unit that detects a document size before reading the document, and the input unit includes: If the document size cannot be detected in advance by the preliminary detection means, the document image is read as a fixed size image.
(4) More preferably, in the image processing apparatus according to any one of (1) to (3), when the document size cannot be detected in advance by the preliminary detection device, the input device sets a maximum document size that can be detected in advance. The image data is read with the included size as the fixed size.
(5) Alternatively, a document processing device, wherein the image processing device according to any one of (1) to (4)
Image forming means for forming, on a sheet medium, an image corresponding to the image data whose background has been removed by the image processing apparatus.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
[First Embodiment]
Hereinafter, an overall configuration of an image input / output system, for example, a copying machine according to a first embodiment and a second embodiment described later will be described with reference to FIG.
[0011]
A reader unit (image input device) 200 optically reads a document image and converts it into image data. The reader unit 200 includes a scanner unit 210 having a function of reading a document, and a document feed (DF) unit 250 having a function of conveying document sheets. The reader unit 200 includes a size sensor 290, and is capable of detecting the size of a document placed on the DF unit 250 and notifying the controller 110 of the detected size of the document.
[0012]
The printer unit (image output device) 300 conveys the recording paper, prints image data thereon as a visible image, and discharges the recording paper outside the apparatus. The printer unit 300 includes a paper feeding unit 310 having a plurality of types of recording paper cassettes, a marking unit 320 having a function of transferring and fixing image data on recording paper, and a printing unit that sorts and staples printed recording paper, And a paper discharge unit 330 having a function of outputting to
[0013]
The control device 110 is electrically connected to the reader unit 200 and the printer unit 300, and is further connected to host computers 401 and 402 via the network 400.
[0014]
The control device 110 controls the reader unit 200 to read the image data of the document, and controls the printer unit 300 to output the image data to recording paper to provide a copy function. Further, a scanner function of converting image data read from the reader unit 200 into code data and transmitting the code data to the host computer via the network 400, converting code data received from the host computer via the network 400 into image data, A printer function for outputting to the printer unit 300 is provided.
[0015]
The operation unit 150 is connected to the control device 110, includes a liquid crystal touch panel, and provides a user I / F for operating the image input / output system.
[0016]
In FIG. 1, a reader unit 200 serving as an image input device illuminates an image on paper serving as a document and scans a CCD line sensor, thereby converting the image into raster image data into an electric signal.
[0017]
Note that a CIS may be used as an image sensor instead of the CCD. In this case, the CIS line sensor is fixed, and paper is fed on the CIS line sensor while being fed from the tray of the DF unit 250, so that the signal is converted into an electrical signal as raster image data.
[0018]
The manuscript paper is set on the tray of the manuscript feeder 250, and when the apparatus user gives an instruction to start reading from the operation unit 150, the controller unit 110 gives an instruction to the reader unit 200 and one manuscript paper from the tray of the DF unit 250 is placed. The document is fed one by one to perform the reading operation of the document image.
[0019]
The DF unit 250 is provided with a size sensor 290 on the tray as means for detecting the size of the document, and can detect the size when the document is placed on the tray. Here, in the case of a long document, such as a long document, the size cannot be detected just by placing it on the tray. The document size is detected by determining whether or not the document size has been detected. As for the main operation direction size, the main operation direction size can be measured by moving the document guide on the tray in accordance with the document.
[0020]
The printer unit 300, which is an image output device, includes a marking unit 320 that converts raster image data into an image on paper. The marking unit 320 is an electrophotographic method using a photosensitive drum or a photosensitive belt. There is an ink jet system for discharging and printing an image directly on a sheet, but any system may be used. Activation of the printing operation is started by an instruction from the controller unit 110. The paper feed unit 310 of the printer unit 300 has a plurality of paper feed stages so that different paper sizes or different paper orientations can be selected, and has a paper cassette corresponding thereto. The paper discharge unit 330 is provided with a paper discharge tray for receiving printed paper.
[0021]
At the time of copying a document, the controller unit 150 selects a sheet of the document size detected by the size sensor 290 from the paper feed cassette unless otherwise specified by the operation unit 150, and selects the selected sheet. A sheet of a size is supplied, and an image read by the reader unit 200 is recorded on the sheet.
[0022]
FIG. 2 is a schematic view of the reader unit 200 and the printer unit 300. The document feeding unit 250 of the reader unit feeds the document one by one on the platen glass 211 in the order of the head, and discharges the document on the platen glass 211 after the reading operation of the document is completed. When the document is conveyed onto the platen glass 211, the lamp 212 is turned on, the movement of the optical unit 213 is started, and the document is exposed and scanned. The light reflected from the original at this time is guided to a CCD image sensor (hereinafter, referred to as a CCD) 218 by mirrors 214, 215, 216 and a lens 217. Thus, the scanned image of the document is read by the CCD 218. The output from the size sensor 290 is also performed in parallel with the document feeding.
[0023]
The reader image processing circuit 222 performs a predetermined process on the image data output from the CCD 218 and outputs the processed data to the control device 110 via the scanner I / F 140.
[0024]
The printer image processing circuit unit 352 outputs an image signal sent from the control device 110 via the printer I / F 145 to the laser driver.
[0025]
The laser driver 317 of the printer unit 300 drives the laser light emitting units 313, 314, 315, and 316, and outputs laser light corresponding to the image data output from the printer image processing unit 352 to the laser light emitting units 313, 314, and 315. 316 are caused to emit light. The laser light is applied to the photosensitive drums 325, 326, 327, and 328 by mirrors 340, 341, 342, 343, 344, 345, 346, 347, 348, 349, 350, and 351. At 328, a latent image corresponding to the laser beam is formed. The developing units 321, 322, 323, and 324 are developing units for developing a latent image with black (Bk), yellow (Y), cyan (C), and magenta (M) toners, respectively. The toner of each color is transferred to a sheet to make a full-color printout.
[0026]
Paper fed from one of the paper cassettes 360 and 361 and the manual feed tray 362 at a timing synchronized with the start of laser light irradiation is adsorbed onto the transfer belt 334 via the registration rollers 333 and is conveyed. Then, the developer attached to the photosensitive drums 325, 326, 327, 328 is transferred to a recording sheet. The recording paper on which the developer is loaded is conveyed to the fixing unit 335, and the developer is fixed on the recording paper by the heat and pressure of the fixing unit 335. The recording paper that has passed through the fixing unit 335 is discharged by a discharge roller 336, and a discharge unit 370 sorts the recording paper by bundling the discharged recording paper and staples the sorted recording paper.
[0027]
When double-sided printing is set, the recording paper is conveyed to the discharge roller 336, the rotation direction of the discharge roller 336 is reversed, and the recording paper is guided to the re-feed conveyance path 338 by the flapper 337. The recording sheet guided to the re-feeding conveyance path 338 is fed to the transfer belt 334 at the timing described above.
[0028]
<Explanation of reader image processing unit>
FIG. 3 is a block diagram illustrating a detailed configuration of the reader image processing unit 222. In the reader image processing unit 222, the original on the platen glass 211 is read by the CCD 218 and converted into an electric signal. In the case of a color sensor, the CCD 218 may be one in which RGB color filters are mounted in-line on a one-line CCD in the order of RGB, or a three-line CCD in which an R filter, a G filter, and a B filter are arranged for each CCD. It does not matter whether the filter is on-chip or the filter is configured differently from the CCD. Then, the electric signal (analog image signal) is input to the image processing unit 222, and the clamp & Amp. The sample / hold (S / H) is performed by the & S / H & A / D unit 301, the dark level of the analog image signal is clamped to the reference potential, and the analog signal is amplified to a predetermined amount (the processing order is not limited to the described order). The signal is D-converted and converted into, for example, a digital signal of 8 bits each of RGB. Then, the RGB signals are subjected to shading correction and black correction by the shading unit 302, and then output to the control device 110. Here, this reader device can mask the image signal in a portion other than the detected original to a fixed value.
[0029]
<Description of control device>
The function of the control device (controller unit) 110 will be described based on the block diagram shown in FIG. The main controller 111 mainly includes a CPU 112, a bus controller 113, and various I / F controller circuits.
[0030]
The CPU 112 and the bus controller 113 control the operation of the entire control device 110. The CPU 112 operates based on a program read from the ROM 114 via the ROM I / F 115. Also, the operation of interpreting PDL (page description language) code data received from the host computer and developing it into raster image data is described in this program and processed by software. The bus controller 113 controls data transfer input / output from each I / F, and performs arbitration at the time of bus contention and controls DMA data transfer.
[0031]
The DRAM 116 is connected to the main controller 111 by a DRAM I / F 117, and is used as a work area for the operation of the CPU 112 and an area for storing image data.
[0032]
The codec 118 compresses the raster image data stored in the DRAM 116 by a method such as MH / MR / MMR / JBIG / JPEG, and expands the compressed and stored code data into raster image data. The SRAM 119 is used as a temporary work area of the Codec 118. The Codec 118 is connected to the main controller 111 via the I / F 120, and data transfer to and from the DRAM 116 is controlled by the bus controller 113 and DMA-transferred.
[0033]
The graphic processor 135 performs image rotation, image scaling, color space conversion, and binarization processing on the raster image data stored in the DRAM 116. The SRAM 136 is used as a temporary work area of the graphic processor 135. The graphic processor 135 is connected to the main controller 111 via the I / F 137, and data transfer to and from the DRAM 116 is controlled by the bus controller 113 and DMA-transferred.
[0034]
The network controller 121 is connected to the main controller 111 by an I / F 122 and is connected to an external network by a connector 122. As a network, Ethernet (registered trademark) is generally used.
[0035]
An expansion connector 124 for connecting an expansion board and an I / O control unit 126 are connected to the general-purpose high-speed bus 125. A general-purpose high-speed bus generally includes a PCI bus.
[0036]
The I / O control unit 126 has two channels of an asynchronous serial communication controller 127 for transmitting and receiving control commands to and from each CPU of the reader unit 200 and the printer unit 300. It is connected to F circuits 140 and 145.
[0037]
The panel I / F 132 is connected to the LCD controller 131 and includes an I / F for displaying on a liquid crystal screen on the operation unit 150 and a key input I / F 130 for inputting hard keys and touch panel keys. Is done.
[0038]
The operation unit 150 has a liquid crystal display unit, a touch panel input device attached on the liquid crystal display unit, and a plurality of hard keys. A signal input from the touch panel or the hard keys is transmitted to the CPU 112 via the above-described panel I / F 132, and the liquid crystal display unit displays the image data sent from the panel I / F 520. The liquid crystal display unit displays a function display, image data, and the like in the operation of the image forming apparatus.
[0039]
The real-time clock module 133 updates and saves the date and time managed in the device, and is backed up by the backup battery 134.
[0040]
The E-IDE interface 161 is for connecting an external storage device. In the present embodiment, the hard disk drive 160 is connected via the I / F, and an operation of storing image data in the hard disk 162 and reading image data from the hard disk 162 is performed.
[0041]
The connectors 142 and 147 are connected to the reader unit 200 and the printer unit 300, respectively, and include a synchronous serial I / F (143, 148) and a video I / F (144, 149).
[0042]
The scanner I / F 140 is connected to the reader unit 200 via the connector 142, and is connected to the main controller 111 via the scanner bus 141, and has a function of performing predetermined processing on an image received from the reader unit 200. And a function of outputting a control signal generated based on the video control signal sent from the reader unit 200 to the scanner bus 141.
[0043]
Data transfer from the scanner bus 141 to the DRAM 116 is controlled by the bus controller 113.
[0044]
The printer I / F 145 is connected to the printer unit 300 via the connector 147, and is connected to the main controller 111 via the printer bus 146. The printer I / F 145 performs predetermined processing on image data output from the main controller 111, It has a function of outputting to the printer unit 300, and also has a function of outputting a control signal generated based on the video control signal sent from the printer unit 300 to the printer bus 146.
[0045]
The transfer of the raster image data developed on the DRAM 116 to the printer unit is controlled by the bus controller 113, and is DMA-transferred to the printer unit 300 via the printer bus 146 and the video I / F 149.
[0046]
<Description of Image Processing Unit of Scanner I / F>
A detailed description will be given of a portion of the scanner I / F 140 that performs image processing. FIG. 5 is a block diagram showing a detailed configuration of a portion of the scanner I / F 140 that performs image processing.
[0047]
When an image signal sent from the reader unit 200 via the connector 142 is used in the connection & MTF correction unit 501 and the CCD 218 is a three-line CCD, the connection processing differs in the reading position between lines. The delay amount for each line is adjusted, the signal timing is corrected so that the reading positions of the three lines are the same, and the MTF correction corrects the change because the reading MTF changes depending on the reading speed. The input masking unit 502 corrects the spectral characteristics of the CCD 218 and the spectral characteristics of the lamp 212 and the mirrors 214, 215, and 216 of the digital signal whose read position timing has been corrected. The output of the input masking unit 502 is sent to the ACS counting unit 503, the histogram counting unit 504, and the main controller 111.
[0048]
The histogram counting unit 504 discretely samples pixels in the designated rectangular area and counts the luminance level of the sampled pixels as the expression frequency, thereby generating a histogram for background level determination. The designated rectangular area corresponds to the document area detected by the size sensor 290. This configuration and procedure will be described later. The histogram counting unit has the configuration and function described in FIG.
[0049]
According to the setting of the software, the histogram counting unit 504 converts the pixel data in the rectangular area surrounded by the start point and the end point in each of the main scanning direction and the sub-scanning direction into RGB and The four types of ND color components synthesized from these are sampled at a constant pitch in the main scanning direction and the sub-scanning direction, and the number of appearances of the luminance level is counted to obtain four (R, G, B, ND). Create a histogram.
[0050]
<Description of ACS counting section and histogram counting section>
The ACS (auto color select) counting section will be described with reference to FIG. Auto color select (hereinafter ACS) determines whether a document is color or black and white. In other words, color determination is performed based on how many pixels that are equal to or greater than a threshold value for calculating the saturation of each pixel. However, even for a black-and-white document, there are many color pixels around the edge when viewed microscopically due to the influence of the MTF and the like, and it is difficult to simply perform the ACS determination in pixel units. Although various methods are provided for the ACS method, the present embodiment is not limited to the ACS method, and therefore will be described using a very general method.
[0051]
As described above, even if a black-and-white image is viewed microscopically, there are a large number of color pixels. Therefore, whether or not the pixel is really a color pixel is determined based on information on a color pixel around the target pixel. There is a need. The filter 601 is a filter for that purpose, and has a FIFO structure in order to refer to a peripheral pixel with respect to a target pixel. The area detection circuit 602 is a circuit that creates an area signal 605 to be subjected to ACS based on the values set in the registers 607 to 610 from the main controller 111 and the video control signal 612 sent from the reader unit 200. A color determination unit 603 refers to peripheral pixels in a memory in the filter 601 for the target pixel based on the area signal 605 to which the ACS is applied, and determines whether the target pixel is a color pixel or a monochrome pixel. It is. The counter 604 counts the number of color determination signals output by the color determination unit 603.
[0052]
The main controller 111 determines an area to be subjected to the ACS with respect to the reading range, and sets the area in the registers 607 to 610 (in this embodiment, the range is determined independently for the document). Further, the main controller 111 compares the value of a counter for counting the number of color determination signals in the area to be subjected to the ACS with a predetermined threshold value, and determines whether the original is color or monochrome.
[0053]
In the registers 607 to 610, the position at which the color determination unit 603 starts the determination and the position at which the determination ends are set in the main scanning direction and the sub-scanning direction based on the video control signal 612 sent from the reader unit 200. Keep it. In the present embodiment, the size is set to be about 10 mm smaller than the actual size of the original.
[0054]
<Description of Image Processing Unit of Printer I / F>
A detailed description will be given of a portion of the printer I / F 145 that performs image processing. FIG. 7 is a block diagram illustrating a detailed configuration of a portion that performs image processing of the printer I / F 145.
[0055]
An image signal sent from the main controller 111 via the printer bus 146 is first input to the background removing unit 706. The background removal unit 706 (non-linear background removal unit) performs an operation for skipping an appropriate background corresponding to the background level calculated from the histogram acquired by the histogram counting unit 613 or the background level set by the UI. To convert the input RGB values (each 8 bits) into output R′G′B ′ (each 8 bits). It is possible to select whether or not to output through R, G, and B through the entire page or on a pixel-by-pixel basis by using an image area flag. The background removal processing is as described in Patent Document 1.
[0056]
The image signal is then input to the LOG converter 701. The LOG conversion unit 701 converts the RGB signals into CMY signals by LOG conversion. Next, the moiré is removed by the moiré removing unit 702. A UCR & masking unit 703 generates a CMYK signal by the UCR process from the CMY signal subjected to the moiré removal processing, and the masking processing unit corrects the CMYK signal to a signal output from the printer. The signal processed by the UCR & masking unit 703 is subjected to density adjustment by the γ correction unit 704 and then subjected to smoothing or edge processing by the filter unit 705. Through these processes, an image is sent to the printer unit 300 via the connector 147.
[0057]
<Description of graphic processor>
The graphic processor 135 will be described in detail. FIG. 8 is a block diagram showing a detailed configuration of the graphic processor 135.
[0058]
The graphic processor 135 has modules for performing image rotation, image scaling, color space conversion, and binarization processing. The SRAM 136 is used as a temporary work area of each module of the graphic processor 135. It is assumed that work areas are statically allocated to each module in advance so that work areas of the SRAM 136 used by each module do not conflict. The graphic processor 135 is connected to the main controller 111 via the I / F 137, and data transfer to and from the DRAM 116 is controlled by the bus controller 113 and DMA-transferred. Data transfer is performed in packet units obtained by dividing image data into a certain size. In each processing unit, processing is performed in packet units.
[0059]
The bus controller 113 performs control for setting a mode or the like for each module of the graphic processor 135 and timing control for transferring image data to each module.
[0060]
<Description of image rotation unit>
The processing procedure in the image rotation unit 801 will be described below. Settings for image rotation control are made from the CPU 112 to the bus controller 113 via the I / F 137. With these settings, the bus controller 113 performs settings (for example, image size, rotation direction, angle, etc.) necessary for image rotation on the image rotation unit 801. After performing the necessary settings, the CPU 112 again permits the bus controller 113 to transfer image data. According to this permission, the bus controller 113 starts transfer of image data from the DRAM 116 or a device connected via each I / F. Here, the image size to be rotated is set to 32 pixels × 32 lines, and when transferring the image data onto the image bus 2008, the image transfer is performed in units of 24 bytes (8 bits each for RGB, one pixel). Assumed to be performed.
[0061]
As described above, in order to obtain an image of 32 pixels × 32 lines, the above-described unit data transfer needs to be performed 32 × 32 times, and image data needs to be transferred from discontinuous addresses. (See Fig. 9)
The image data transferred by the discontinuous addressing is written to the SRAM 136 such that the image data is rotated at a desired angle at the time of reading. For example, if the rotation is 90 degrees counterclockwise, the image data to be transferred is written in the Y direction as shown in FIG. By reading in the X direction at the time of reading, the image is rotated.
[0062]
After the image rotation of 32 pixels × 32 lines (writing to the SRAM 136) is completed, the image rotating unit 801 reads out the image data from the SRAM 136 by the above-described reading method, and transfers the image to the bus controller 113.
[0063]
The bus controller 113 that has received the rotated image data transfers the data to the DRAM 116 or each device on the I / F by continuous addressing.
[0064]
Such a series of processing is repeated until there is no more processing request from the CPU 112 (when processing of the required number of pages is completed).
[0065]
<Explanation of image scaling unit>
The processing procedure in the image scaling unit 802 will be described below. Via the I / F 137, the CPU 112 makes settings for image scaling control in the bus controller 113. With this setting, the bus controller 113 performs settings necessary for image scaling (the scaling ratio in the main scanning direction, the scaling ratio in the sub-scanning direction, the image size after scaling, etc.) for the image scaling unit 802. After performing the necessary settings, the CPU 112 again permits the bus controller 113 to transfer image data. According to this permission, the bus controller 113 starts transfer of image data from the DRAM 116 or a device connected via each I / F.
[0066]
The image scaling unit 802 stores the received image data in the temporary SRAM 136, and uses the image data as an input buffer. The stored data has the required number of pixels and the number of lines according to the scaling ratio of main scanning and sub scanning. The magnification process is performed by enlarging or reducing the image by performing an interpolation process corresponding to. The data after scaling is written back to the SRAM 136 again, and the image scaling unit 802 reads the image data from the SRAM 136 using this as an output buffer, and transfers it to the bus controller 113.
[0067]
The bus controller 113 receiving the image data subjected to the scaling process transfers the data to the DRAM 116 or each device on the I / F.
[0068]
<Description of color space conversion unit>
The processing procedure in the color space conversion unit 803 will be described below. Settings for color space conversion control are made from the CPU 112 to the bus controller 113 via the I / F 137. With this setting, the bus controller 113 makes settings (coefficients of matrix operation, table values of the LUT 804, etc., described later) necessary for the color space conversion process for the color space conversion unit 803 and the LUT (look-up table) 804. After performing the necessary settings, the CPU 112 again permits the bus controller 113 to transfer image data. According to this permission, the bus controller 113 starts transfer of image data from the DRAM 116 or a device connected via each I / F.
[0069]
The color space conversion unit 803 first performs a 3 × 3 matrix operation represented by the following equation for each pixel of the received image data.
[0070]
(Equation 1)

[0071]
In the above equation, R, G, B are inputs, X, Y, Z are outputs, a11, a12, a13, a21, a22, a23, a31, a32, a33, b1, b2, b3, c1, c2, c3 are Each is a coefficient.
[0072]
Various color space conversions such as conversion from the RGB color space to the Yuv color space can be performed by the calculation of the above expression.
[0073]
Next, conversion by the LUT 804 is performed on the data after the matrix operation. As a result, nonlinear conversion can be performed. Naturally, by setting a through table, LUT conversion can not be performed substantially.
[0074]
After that, the color space conversion unit 803 transfers the image data subjected to the color space conversion processing to the bus controller 113.
[0075]
The bus controller 113 that has received the color space converted image data transfers the data to the DRAM 116 or each device on the I / F.
[0076]
<Description of image binarization unit>
The processing procedure in the image binarization unit 805 will be described below. Via the I / F 137, the CPU 112 makes settings for binarization control in the bus controller 113. With this setting, the bus controller 113 performs settings (various parameters and the like according to the conversion method) necessary for the binarization processing on the image binarization unit 805. After performing the necessary settings, the CPU 112 again permits the bus controller 113 to transfer image data. According to this permission, the bus controller 113 starts transfer of image data from the DRAM 116 or a device connected via each I / F.
[0077]
The image binarization unit 805 performs a binarization process on the received image data. In the present embodiment, the binarization method is to simply binarize image data by comparing it with a predetermined threshold. Of course, any method such as a dither method, an error diffusion method, or an improved error diffusion method may be used.
[0078]
After that, the image binarization unit 805 transfers the image data subjected to the binarization processing to the bus controller 113. The bus controller 113 receiving the binarized image data transfers the data to the DRAM 116 or each device on the I / F.
[0079]
<Sequence when outputting PDL image>
FIG. 11 is a flowchart illustrating a procedure of outputting a PDL image according to the present embodiment. Note that S1101 to S1109 in the figure indicate each step.
[0080]
When outputting a PDL image, in step S1101, the user performs print settings for the PDL image output job on the PC 401. The print setting contents include the number of copies, paper size, one side / two sides, page output order, sort output, and whether or not stapling is performed. Here, when executing tab sheet printing, a tab sheet mode is set.
[0081]
In step S1102, a print instruction is given on the PC 401, and at the same time, driver software installed on the PC 401 converts code data on the PC 401 to be printed into so-called PDL data, together with the print setting parameters set in step S1101. The PDL data is transferred to the control device 110 of the image input / output device via the network 400.
[0082]
In step S1103, the CPU 112 of the main controller 111 of the control device 110 develops (rasterizes) the PDL data transferred via the connector 122 and the network controller 121 into image data based on the print setting parameters. The development of the image data is performed on the DRAM 116. Upon completion of the image data development, the process advances to step S1104.
[0083]
In S1104, the main controller 111 transfers the image data expanded on the DRAM 116 to the graphic processor 135.
[0084]
In step S1105, the graphic processor 135 performs image processing independently of the print setting parameters. For example, if the paper size specified by the print setting parameter is A4, but the paper supply unit 360 of the printer unit 300 has only A4R paper, the graphic processor 135 rotates the image by 90 degrees. Thus, an image can be output according to the output sheet. When the image processing of the image data is completed, the process proceeds to S1106.
[0085]
In step S1106, the graphic processor 135 transfers the image data after the image processing to the main controller 111. The main controller 111 stores the transferred image data on the DRAM 116.
[0086]
In step S1107, it is determined based on the setting in step S1101 whether the print mode is set to the tab sheet mode.
[0087]
If it is determined in step S1107 that the current mode is not the tab sheet mode, the process advances to step S1108. In step S1108, the main controller 111 controls the printer unit 300 via the printer I / F 145 and the connector 147 and stores the data in the DRAM 116 at appropriate timing. Is transferred to the printer unit 300.
[0088]
In step S1109, the control device 110 controls the printer unit 300 to print out image data. When the transfer of the image data is completed, that is, when the PDL job ends, the print output ends.
[0089]
On the other hand, if it is determined in step S1107 that the current mode is the tab sheet mode, the process advances to step 1110 to form a tab sheet image on the DRAM using FIG.
[0090]
The flow advances to step S1108 to transfer the generated image data from the DRAM to the printer. In step S1109, the image is printed on a preset tab sheet, and the process ends.
[0091]
<Sequence when outputting a copy image>
FIG. 12 is a flowchart illustrating a procedure of outputting a copy image according to the present embodiment. In addition, S1201 to S1208 in the figure show each step.
[0092]
In the case of outputting a copy image, in S1201, the user performs copy settings for the copy image output job on the operation unit 150. The copy setting contents include the number of copies, paper size, one-sided / two-sided, enlargement / reduction ratio, sort output, and whether or not stapling is performed. Here, when the tab sheet printing is executed, the tab sheet mode is set.
[0093]
In step S1202, when a copy start instruction is given on the operation unit 150, the main controller 111 of the control device 110 controls the reader unit 200 via the scanner I / F 140 and the connector 142 to read image data of a document. First, the document feeding unit 250 feeds the placed documents one by one onto the platen glass 211, and at the same time, detects the size of the document. The image data is read by exposing and scanning the original based on the detected size of the original. The read image data is stored on the DRAM 116. In the conventional copying machine, the magnification in the sub-scanning direction is realized by changing the moving speed of the optical unit 213 in accordance with the enlargement / reduction ratio of the copy setting, that is, in accordance with the magnification in the sub-scanning direction. Was. However, in the present embodiment, image data is always read at the same magnification (100%) regardless of the setting of the enlargement / reduction ratio in the copy setting, and the scaling process is described later in both the main scanning direction and the sub-scanning direction. To be performed by the graphic processor 135.
[0094]
In step S1203, the main controller 111 transfers the image data on the DRAM 116 to the graphic processor 135.
[0095]
In S1204, the graphic processor 135 performs image processing based on the copy setting parameters. For example, when the enlargement is set to 400%, the image scaling unit, which is a module in the graphic processor 135, performs scaling processing in both the main scanning direction and the sub-scanning direction. When the image processing of the image data is completed, the process proceeds to S1205.
[0096]
In step S1205, the graphic processor 135 transfers the image data after the image processing to the main controller 111. The main controller 111 stores the transferred image data on the DRAM 116.
[0097]
In step S1206, based on the setting in step S1201, it is determined whether the print mode is set to the tab sheet mode.
[0098]
If it is determined in step S1206 that the current mode is not the tab sheet mode, the process advances to step S1207. In step S1207, the main controller 111 controls the printer unit 300 via the printer I / F 145 and the connector 147 and stores the data in the DRAM 116 at appropriate timing. Is transferred to the printer unit 300.
[0099]
In step S1208, the control device 110 controls the printer unit 300 to print out image data. When the transfer of the image data is completed, that is, when the copy job ends, the print output ends.
[0100]
On the other hand, if it is determined in step S1206 that the mode is the tab sheet mode, the process advances to step 1110 to form a tab sheet image on the DRAM using FIG.
[0101]
The flow advances to step S1208 to transfer the generated image data from the DRAM to the printer. In step S1208, the image is printed on a preset tab sheet, and the process ends.
[0102]
<Embodiment of image packet structure>
FIG. 13 is a diagram illustrating a packet structure according to the present embodiment. One packet is composed of a data body 10 containing one tile of image data of 32 × 32 pixels and a header 12. The header 12 includes a packet ID 14 indicating the serial number of the packet, a compression flag 16 indicating whether the image data contained in the data body 10 is compressed, and an image representing the amount of image data contained in the data body 10. The data length 18 is provided. In the present embodiment, the packet ID 14 is 1 byte, the compression flag 16 is 1 bit, and the data length 18 is 2 bytes. In addition to the above, arbitrary information such as a flag indicating the compression method, a flag for determining the image area, a result of the ACS determination, and color space information can be included in the packet header.
[0103]
FIG. 14 shows a state in which one page of image data is divided into tiles of 32 × 32 pixels. One tile of image data is contained in one packet as shown in FIG. One tile may not be 32 × 32 pixels, for example, may be 64 × 64 pixels, and may be not a square but a rectangle. When one tile is 32 pixels × 32 pixels, for example, when A4 has a resolution of 600 dpi, the number of tiles is 220 × 156 = 34320, and when A3 is 1200 dpi, the number of tiles is 440 × 624 = 274,560. Become.
[0104]
In the present embodiment, when compressing image data, it is determined whether to compress image data in packet units, that is, in tile units, instead of compressing one page at a time. If the data amount after compression is larger than the data amount before compression, compression is not performed.
[0105]
Since the packet of the present embodiment includes the compression flag 16 in the header 12, it can be identified by the compression flag 16 whether the data body 10 contains compressed image data or uncompressed image data. When the compressed image data is stored in the data body 10, the compression flag is set to “1”. When the data body 10 contains the uncompressed image data, the compression flag is set to “0”. In one page, packets having compressed image data and packets having non-compressed image data are mixed.
[0106]
For example, it is assumed that there is one page of plain image data, and when compressing this, the image data format of the present embodiment is adopted. First, the page image data is divided into tiles as shown in FIG. The image data for each tile is compressed by, for example, the JPEG method. The compression method may be another method. As a result of the compression, when the data amount becomes smaller than the original image data amount, the compressed image data is stored in the data body 10 of the packet, the data amount is stored in the data length 18 of the header 12, and the compression flag 16 Set '1'. Conversely, as a result of the compression, when the data amount becomes larger than the original image data amount, the uncompressed image data is stored in the data body 10 of the packet, and the data amount is stored in the data length 18 of the header 12. , Set the compression flag 16 to “0”.
[0107]
In this way, data compression and packetization are repeated for each tile to create one page of data. It is possible to guarantee that the data of one page thus formed does not exceed the original image data amount for the data body 10 of each packet. Since the data amount of the header 12 is fixed (4 bytes), the maximum value of the total data amount of one page is (the amount of uncompressed image data of one tile + the data amount of header of 4 bytes) × (the number of tiles of one page) Is calculated by
[0108]
When decompressing uncompressed image data by expanding page image data in which compressed / uncompressed packets are mixed, the compression flag 16 of the header 12 of each packet is referred to and is "1". Only the data contained in the packet needs to be expanded.
[0109]
As described above, in the present embodiment, it is only necessary to temporarily hold the uncompressed image data for one tile, so that the memory capacity for that is small. After the compression of the image data of the tile is completed and the packet of the tile is generated, the image data of the tile may be deleted. That is, every time the image data of one tile is compressed and packetized, the original image data of that tile can be deleted. As a result, the work area of the memory required for compression only needs to have the capacity of image data for one tile.
[0110]
FIG. 15 is a block diagram illustrating a configuration related to packet data generation in the present embodiment. The processing blocks in FIG. 15 excluding the memory 116 are included in the main controller 111 shown in FIG. 112 is a CPU, 22 is a memory control circuit, and 116 is a memory (DRAM). A system bus 34 connects the CPU 20, the memory control circuit 22, and the DMA control circuit 32.
[0111]
Reference numeral 26 denotes an input terminal for inputting image data to be processed, and reference numeral 28 denotes a packet generation circuit for forming the image data input to the input terminal 26 into a packet described with reference to FIGS. The packet generation circuit 28 includes an image compression circuit that compresses image data in tile units. Reference numeral 30 denotes a buffer for temporarily storing image data before and after image compression. Reference numeral 32 denotes a DMA control circuit that transfers an output packet of the packet generation circuit 28 to the memory 24 via the memory control circuit 22 in a DMA (Direct Memory Access) system.
[0112]
The basic data flow will be described. Image data input from the scanner I / F 140 or the like is input to the input terminal 26 in units of 32 × 32 pixel tiles. The packet generation circuit 28 compresses the image data in tile units, compares the non-compressed image data with the compressed image data, stores the smaller data amount in the data body 10, and sets the compression flag 16 of the header 12 to “0”. 'Or' 1 'is set and output to the DMA control circuit 32 in the packet format shown in FIG. The DMA control circuit 32 writes the packet data from the packet generation circuit 28 to the memory 24 via the system bus 34 and the memory control circuit 22.
[0113]
FIG. 16 is a block diagram showing a schematic configuration of the packet generation circuit 28. The compression circuit 40 stores the image data in tile units from the input terminal 26 in the buffer 30 and also compresses and stores the compressed image data in the buffer 30, and compares the non-compressed image data with the compressed image data, Outputs the data amount. That is, when the amount of image data after compression is smaller than the amount of image data before compression, the compression circuit 40 outputs the compressed image data to the merge circuit 44, and outputs the compressed image data to the header generation circuit 42 and the merge circuit 44. It notifies that the compressed data is compressed data and the amount of data. Conversely, when the image data amount after compression is larger than the image data amount before compression, the compression circuit 40 outputs the image data before compression to the merge circuit 44 and also outputs the merged circuit data to the header generation circuit 42. The data output to 44 is notified that the data is uncompressed data and the data amount.
[0114]
The header generation circuit 42 increments the packet ID 14 in order, sets the data amount to the image data length 18, and sets “0” for the compression flag 16 when the compression circuit 40 outputs uncompressed data to the merge circuit 44. Set to "1" when the compression circuit 40 outputs compressed image data to the merge circuit 44. Then, the header generating circuit 42 outputs the generated header information to the merge circuit 44.
[0115]
The merge circuit 44 merges the header from the header generation circuit 42 and the data from the compression circuit 40 to generate a packet having the format shown in FIG. The generated packet is sent to the DMA control circuit 32.
[0116]
The DMA control circuit 32 includes a packet address register indicating an address for storing the packet data. The DMA control circuit 32 writes the packet from (the merge circuit 44 of) the packet generation circuit 28 to the address of the memory 116 indicated by the packet address register. The packet address register adds and updates the stored value by the packet capacity. Thereafter, the DMA control circuit 32 receives the next packet from the packet generation circuit 28.
[0117]
FIG. 17 shows the relationship between the packet data and the packet table. In the figure, 1700 is a packet table indicating the start address 1701 of each packet on the memory, and 1702 is a repeat flag. The flag is turned on when the data is the same as the immediately preceding packet, and is set off when the data is different. Is done. Reference numeral 1710 denotes a packet data area stored in the memory, which is schematically shown as shown. The packet 1711 and the address on the table have a one-to-one correspondence, and the packet 1712 and the address on the table have a one-to-two correspondence by using a repeat flag.
[0118]
<Embodiment of background level determination>
FIG. 18 is a block diagram showing the background level determination. In FIG. 18, an image signal generation unit 1801 corresponds to the reader image processing unit 222 of the reader unit 200, and a document size detection unit 1802 corresponds to the size sensor 290 of the reader unit 200. When the output signal of the size sensor 290 is converted into a document size by the main controller 111 or the like, the processing by the main controller 111 or the like is included. Further, the histogram generation unit 1803 and the histogram generation area change unit 1804 are included in the histogram count unit 504 of the scanner I / F 140. The background removal processing unit 1805 and the background level determination unit 1806 are included in the background removal unit 706 of the printer I / F unit 145.
[0119]
When a document is pulled into the feeder and starts to be read by a reading device such as a CCD / CIS, the image signal generating unit 1801 converts the image into RGB luminance signals and sends the data to the subsequent stage. From the luminance signal, the histogram generation means 1803 extracts pixels at a fixed or specified sampling pitch and counts the luminance levels to generate a histogram for each of the RGB colors.
[0120]
If the document size is not known before the start of scanning, the processing after the image signal generation unit 1801 performs processing on the length of the image of the assumed maximum size (the width is identifiable, so the maximum size determined for the width). It is common to perform the processing assuming that For example, the assumed maximum size is set to a size larger than the maximum document size that can be detected in advance by the document size detection unit 1802 before reading the document. Even if the document size is not actually the maximum length, the image signal generation unit 1801 already sends the image size or the like to the image processing device (controller unit 110 including a graphic processor or the like) at the subsequent stage (that is, the destination of the image data). Since the region to be processed has been passed and set, the image signal is generated with the maximum length in accordance with the region.
[0121]
Here, the document size information determined by the reader unit 200 or the main controller unit 110 based on the signal detected by the document size detection unit 1802 during the generation of the image signal is directly transmitted from the document size unit 1802 via the controller unit 110 or from the document size unit 1802. Is transmitted to the histogram generation area changing unit 1804 of the histogram counting unit 613 included in the scanner IF unit 145. The histogram generation area changing unit 1804 changes the area of the image data sampled by the histogram generation unit 1803 to the document size. For example, it is assumed that the actual document size and the scanned size received from the controller unit 110 or the reader IF unit 140 are both expressed in a format of “width (dot) × length (dot)”. In this case, for both the width and the length, the size of the image data for which the histogram is to be created is replaced with the original size where the original size is the scanned size. However, it is assumed that the image data corresponding to the document starts from a fixed position in the scanned image data, such as the top of the scanned and read image data.
[0122]
After the document is scanned, a background level determination unit 1806 determines the background level from the histogram sampled from the document area by the histogram generation unit 1803, sets a coefficient for skipping the background to a background removal processing unit 1805, and sets a background removal processing unit. A step 1805 performs a process of skipping the background of the image data.
[0123]
For example, the background level is set to a luminance having the highest frequency of distribution for each color component, and a pixel having a luminance in the vicinity (within a certain error range) of all color components is replaced with a pixel having the highest luminance (white). Thus, it is conceivable to replace all the background with white and to skip the background. Also, for example, when the density of the background is high, the density of the object drawn on the background may be lower. In such a case, if the background is replaced with white, the visibility of the object is rather deteriorated. It is possible. Therefore, it is conceivable that the replacement is performed only when the density of the background is equal to or less than a certain density (more than a certain brightness).
[0124]
FIG. 21 shows a processing procedure executed by the histogram counting unit 613 shown in FIG. When the scanner IF unit 140 is controlled by, for example, a computer having a processor and a memory, the procedure of FIG. 21, that is, the histogram counting unit 613 is realized by executing the program of the procedure of FIG. 21 by the processor. In this case, a frequency counter for each color component and each luminance of the histogram is secured in its memory.
[0125]
First, the area size for which a histogram is to be generated is replaced from the scanned size with the document size received from the reader unit 200 (or from the main controller 111 when the document size is determined by the main controller 111) ( S2101). Thus, a histogram can be generated according to the actual document size.
[0126]
Then, for the target pixel in the set area, one is added to the frequency counter corresponding to the luminance of each color component of the target pixel (S2102). The luminance of the MD component is also obtained, and 1 is added to the frequency of the corresponding luminance.
[0127]
Then, it is determined whether or not all pixels in the set area have been counted (S2103). If not, the pixel of interest is moved to the next pixel in the set area to continue the histogram generation processing.
[0128]
The histogram generated in this procedure is transmitted to the printer I / F unit 145 via the main controller 111 or directly, and is used for the background removal processing by the background removal unit 706. Of course, instead of the histogram itself, the background level determination unit 1907 can be realized in the main controller 111, and the background level determined there can be transmitted to the printer I / F to perform the undercolor removal processing.
[0129]
When the document size is determined by the above configuration and processing, the area for calculating the histogram can be changed, and the image data of the area not included in the document is not subjected to histogram generation. It is possible to detect with high accuracy.
[0130]
[Second embodiment]
Next, a second embodiment will be described. In the second embodiment, the configurations in FIGS. 1 to 17 are common to the first embodiment. 19 and 22 are provided in place of FIGS. 18 and 21.
[0131]
FIG. 19 is a block diagram showing the background level determination in the case of the second embodiment. In FIG. 19, an image signal generating unit 1901 and a mask unit 1903 outside the document area correspond to a reader image processing unit 222 of the reader unit 200, and a document size detecting unit 1902 corresponds to a size sensor 290 of the reader unit 200. When the output signal of the size sensor 290 is converted into a document size by the main controller 111 or the like, the processing by the main controller 111 or the like is included.
[0132]
Further, the histogram generation unit 1904 is included in the histogram count unit 504 of the scanner I / F 140. Further, the mask area removing unit 1905 is realized by the main controller 111.
[0133]
The background removal processing unit 1906 and the background level determination unit 1807 are included in the background removal unit 706 of the printer I / F unit 145.
[0134]
When a document is pulled into the feeder and started to be read by a reading device such as a CCD / CIS, the image signal generation unit 1901 converts the image into RGB luminance signals and sends the data to the subsequent stage. From the luminance signal, the histogram generation unit 1904 extracts pixels at an arbitrary sampling pitch, and generates a histogram for each of the RGB colors by counting the luminance levels.
[0135]
If the document size is not known before the start of scanning, the processing after the image signal generation unit 1901 is generally performed assuming the length of the image of the assumed maximum size. Even when the document size is not the maximum length, the image signal generation unit 1901 may generate an image signal with the maximum length because an area such as the image size has already been set in an image processing device or the like at the subsequent stage. Can be
[0136]
That is, in such a case, the document size information can be acquired at the time when the document has been scanned in the reader unit 200. However, since the size of the original to be read is already notified to the controller 110 at the subsequent stage and the size to be scanned is notified, the image data must be transmitted to the controller 110 at the notified size. Therefore, for portions other than the region corresponding to the document, pixel data having a constant luminance, for example, pixel data having the highest luminance is filled (masked) by the document area outside mask portion 1903. The area filled with the pixel data of constant luminance is called a mask area.
[0137]
Here, when the timing at which the document size determined by the document size detection unit 1902 reaches the histogram counting unit 613 is after the histogram generation unit 1904 processes the data of the document size, it corresponds to the document as in the first embodiment. It is not possible to generate a histogram only for a region to be changed. Thus, in the present embodiment, the histogram counting unit 613 of the scanner I / F 145 samples the histogram of the entire image data once received from the reader unit 200. Thereafter, the mask area removing unit 1905 obtains an area obtained by removing the original size received by the original size detecting unit 1932 from the scanned size, that is, the size of the mask area (for example, the number of pixels in the vertical direction × the number of pixels in the horizontal direction). . Then, from the histogram generated by the histogram generation unit 1904, the frequency of the pixel data of a fixed luminance filled by the out-of-document area mask unit 1903 (that is, the number of filled pixels) is subtracted for each color component. By doing so, the histogram of only the document area is generated again.
[0138]
The background level determination unit 1907 determines the background level from the histogram of only the document area, sets a coefficient for skipping the background to the background removal processing unit 1906, and the background removal processing unit 1906 performs a process of removing the background of the image data.
[0139]
Here, FIG. 20 is a diagram showing details in the case described with reference to FIG.
[0140]
The scan image 2000 includes a document area 2001 and a mask area 2002 having a specific luminance 255 (the part denoted by reference numeral 2005 in FIG. 20) filled by the mask area 1903 outside the document area. On the other hand, it is assumed that the area corresponding to the document includes an area 2003 with a luminance of 150 and an area 2004 with a luminance of 255. In this case, the histogram generated by the histogram generation unit 1904 indicates the distribution of pixel values including the mask area, as shown in the histogram 2010.
[0141]
The horizontal axis of the histogram 2010 in FIG. 20 indicates the luminance (0-255), and the vertical axis indicates the frequency of counting the pixels having the luminance. Here, in the scanned image 2000, since the area of the luminance 255 is large in two places of the area 2004 and the area 2005, the count number 2007 of the luminance 255 exceeds the count number 2006 of the luminance 150 in the area 2003. When the background level is determined from the histogram 2010, the luminance 255 is used as the background, and practically no background removal is performed.
[0142]
Here, when the mask area removing unit 1905 subtracts the count number of the area 2005 that can be taken from the count number 2007 of the luminance 255, a histogram like a histogram 2011 is obtained, and the count number 2008 of the luminance 150 becomes the count number 2009 of the luminance 255. By determining that the luminance 150 is the background and setting the background removal processing unit 1906 to skip the luminance 150 as the background, the color of the background 2003 of the scanned document is skipped, and an image 2012 is obtained. For this reason, the background of the original document is removed by the background removal process, and an image in which objects such as characters and photographs without the background are easily visible can be formed.
[0143]
FIG. 22 shows a processing procedure executed by the histogram counting unit 613 shown in FIG. When the scanner IF unit 140 is controlled by, for example, a computer having a processor and a memory, the procedure of FIG. 22, that is, the histogram counting unit 613 is realized by executing the program of the procedure of FIG. 21 by the processor. In this case, a frequency counter for each color component and each luminance of the histogram is secured in its memory.
[0144]
First, the size of the entire scanned area received from the reader unit 200 (or from the main controller 111 when the document size is determined by the main controller 111) is set as the area size for which a histogram is to be generated ( S2201).
[0145]
Then, for the target pixel in the set area, one is added to the frequency counter corresponding to the luminance of each color component of the target pixel (S2202). The luminance of the MD component is also obtained, and 1 is added to the frequency of the corresponding luminance.
[0146]
Then, it is determined whether or not all the pixels in the set area have been counted (S2203). If not, the pixel of interest is moved to the next pixel in the set area, and the histogram generation processing is continued (S2204).
[0147]
The histogram generated in this procedure is transmitted to the main controller 111. In the main controller 111, the number of pixels in the mask area is subtracted from the frequency of the pixel value filled in the mask area in the generated histogram (S2211). . This process is performed for each color component. As a result, a histogram of an area corresponding to the document is obtained. The histogram itself or the background level obtained from the histogram is directly transmitted to the printer I / F unit 145 and used for background removal processing by the background removal unit 706.
[0148]
Note that the processing by the mask region removing unit 1905 can also be executed by the scanner IF unit 140.
[0149]
With the above configuration and processing, even when it is impossible to change the area for calculating the histogram when the document size is determined, the frequency corresponding to the invalid image area other than the document is subtracted from the calculated histogram. Thus, the background level of the document can be detected with high accuracy.
[0150]
(Other embodiments)
In the above-described embodiment, an example in which the present invention is applied to a digital multi-functional peripheral has been described. However, the present invention is not limited to this. For example, a facsimile apparatus, a printer, and the like for transmitting an image scanned by a scanner It goes without saying that the present invention is applicable to printing in other image forming apparatuses. Further, the present invention is not limited to the image forming apparatus, and may be applied to, for example, a printer driver on a personal computer or image processing software.
[0151]
Further, according to the present invention, a storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to a system or an apparatus, and a computer (or CPU or MPU) of the system or apparatus stores the storage medium (for example, It goes without saying that the program code is also completed by reading and executing the program code stored in the RAM 31) in the present embodiment described above.
[0152]
In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, or ROM is used. Can be. When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS or the like running on the computer performs the actual processing based on the instruction of the program code. It goes without saying that a case where some or all of the operations are performed and the functions of the above-described embodiments are realized by the processing is also included.
[0153]
Furthermore, after the program code read from the storage medium is written in the memory provided in the function expansion board inserted into the computer or the function expansion unit connected to the computer, based on the instruction of the next program code, It goes without saying that a CPU included in an expansion board or an expansion unit performs the extended function to perform a part or all of the actual processing, and the processing implements the functions of the above-described embodiments.
[0154]
The present invention can also be realized by arranging an apparatus including such a storage medium on a network, downloading a program stored in the storage medium to a predetermined apparatus via the network, and executing the downloaded program. Needless to say, the functions of the above embodiment are realized.
[0155]
【The invention's effect】
As described above, according to the present invention, the background level of a document can be detected with high accuracy by changing the area for calculating the histogram when the document size is determined.
[0156]
If it is not possible to change the area for calculating the histogram when the document size is determined, the histogram of the invalid image area sentence other than the document is subtracted from the calculated histogram to obtain the background level of the document. Can be detected with high accuracy.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an overall configuration of an image input / output system according to an embodiment.
FIG. 2 is a schematic view of a reader unit 200 and a printer unit 300.
FIG. 3 is a block diagram illustrating a detailed configuration of a reader image processing unit 222.
FIG. 4 is a block diagram of the control device 110.
FIG. 5 is a block diagram showing a detailed configuration of a portion that performs image processing of a scanner I / F 140.
FIG. 6 is a diagram illustrating an ACS (auto color select) counting unit.
FIG. 7 is a block diagram illustrating a detailed configuration of a portion that performs image processing of a printer I / F 145.
FIG. 8 is a block diagram showing a detailed configuration of the graphic processor 135.
FIG. 9 is a diagram for explaining addresses of tile images.
FIG. 10 is a diagram illustrating a rotation process.
FIG. 11 is a flowchart illustrating a procedure of outputting a PDL image according to the embodiment.
FIG. 12 is a flowchart illustrating a procedure of outputting a copy image according to the embodiment.
FIG. 13 is a diagram illustrating a packet structure according to the present embodiment.
FIG. 14 is a diagram illustrating a state in which one page of image data is divided into tiles of 32 × 32 pixels.
FIG. 15 is a block diagram illustrating a configuration related to packet data generation in the present embodiment.
FIG. 16 is a block diagram showing a schematic configuration of a packet generation circuit 28.
FIG. 17 is a diagram showing a relationship between packet data and a packet table.
FIG. 18 is a block diagram illustrating a background level determination method according to the first embodiment.
FIG. 19 is a block diagram illustrating a background level determination method according to the second embodiment.
FIG. 20 is a diagram illustrating a background level determination method according to the second embodiment.
FIG. 21 is a flowchart illustrating a base level determination procedure according to the first embodiment.
FIG. 22 is a flowchart showing a base level determination procedure according to the second embodiment.
[Explanation of symbols]
110 controller
112 CPU
116 DRAM
135 Graphic Processor
200 reader device
300 Printer

Claims (9)

Input means for reading the original image as an image of a certain size;
Size detecting means for detecting a document size while reading a document image by the input means,
Histogram creation means for creating a histogram of a luminance distribution according to the size detected by the size detection means, for image data of the fixed size image read by the input means,
An image processing apparatus comprising: a background removal processing unit configured to remove a background level of the document image from the image data based on the histogram. Input means for detecting a document size while reading the document image as a fixed size image, and filling fixed color pixels for image data within the fixed size and outside the document size;
Histogram creating means for creating a histogram of the luminance distribution for the image data read by the input means,
Correction means for correcting by subtracting the frequency of a certain color filled by the input means from the histogram,
An image processing apparatus comprising: a background removal processing unit configured to remove a background level of the document image from the image data based on the histogram corrected by the correction unit. The input means further includes preliminary detection means for detecting the document size in advance before reading the document, and the input means converts the document image to a fixed size image when the preliminary detection means cannot detect the document size in advance. The image processing apparatus according to claim 1, wherein the image processing apparatus reads the image data as an image. 4. The image processing apparatus according to claim 1, wherein the input unit reads the image data with the size including a maximum detectable document size as the fixed size when the preliminary detection unit cannot detect the document size in advance. An image processing device according to any one of the above. An image processing apparatus according to any one of claims 1 to 4,
An image forming unit for forming, on a sheet medium, an image corresponding to the image data whose background has been removed by the image processing apparatus. A histogram creation step of creating a histogram of a luminance distribution according to the document size, for image data of the fixed size image read by the input means for detecting the document size while reading the document image as a fixed size image;
A background removal processing step of removing a background level of the document image from the image data based on the histogram. The original size is detected while reading the original image as an image of a certain size, and a histogram of the luminance distribution is obtained for the image data read by the input unit that fills pixels of a certain color with respect to the image data within the certain size and outside the size of the original. A histogram creation process to be created,
A correction step of correcting by subtracting the frequency of the fixed color filled by the input means from the histogram,
A background removal processing step of removing a background level of the document image from the image data based on the histogram corrected in the correction step. A program for causing a computer to execute the image processing method according to claim 6. A computer-readable recording medium on which the program according to claim 8 is recorded.

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