JP3684181B2 - Image processing apparatus and image processing method - Google Patents

Description

【００９１】
但し、Ｃ（ｘ）＝１／√２ （ｘ＝０），
Ｃ（ｘ）＝１ （ｘ≠０）・・・式６
で与えられる。
【００９２】
１１０３は、クラス分類部を示し、直交変換係数の帯域毎にクラス分類する。図１２は、Ｐ＝Ｑ＝１６の時のクラス分類の一例を示している。図１２は、１ブロック内の直交変換係数F（u，v）を表していて、左上がＤＣ成分、残りの２５５成分がＡＣ成分となる。
【００９３】
いま、F（4，8）を中心とするクラスＡと、F（8，4）を中心とするクラスＢの２クラスを作成する。２クラスを図中、太線で示す。このクラス分類手段は、全２５６成分をクラス分類する必要はなく、所望の成分を中心とした複数のクラスに分類するだけで良い。この必要なクラス数は、多重化時に量子化制御した条件数に対応する。すなわち、量子化制御した条件数よりもクラス数は多くなることはない。
【００９４】
１１０４は、電力比較部を示し、各クラスの電力の総和を比較する手段である。演算を高速にする為に、発生した変換係数の絶対値を電力の代用としても良い。各クラスの電力の総和を比較することで、付加情報の信号を判断する。
【００９５】
いま、多重化時に図６（ａ）、（ｂ）の量子化条件Ａ、Ｂを施した例について説明する。前述したように、量子化条件Ａ、Ｂを用いた量子化では、各々角度の異なる斜め方向にドットが並ぶテクスチャが発生しやすい。
【００９６】
すなわち、量子化条件Ａにおいて量子化したブロックでは、直交変換処理を行うと、図１２のクラスＡに大きな電力が発生する。一方、量子化条件Ｂにおいて量子化したブロックでは、直交変換処理を行うと、図１２のクラスＢに大きな電力が発生する。
【００９７】
すなわち、クラスＡとクラスＢの電力の大小関係を相対的に比較することにより、該当するブロックの多重化時の量子化条件が、量子化条件Ａ、量子化条件Ｂの何れであるかが判断できる。量子化条件は、付加情報の符号（式３のbit）に連動している為、量子化条件が識別できるということは、多重化された符号が特定できることに相当する。
【００９８】
図４に示したフローチャートの例では、bit＝０を量子化条件Ａ、bit＝１を量子化条件Ｂに設定している為、クラスＡの電力の方が大きい場合には、bit＝０、クラスＢの電力の方が大きい場合には、bit＝１と判断できる。
【００９９】
以上、２種の復号部を説明したが、本実施形態の復号部の切り替えは、復号検出率と復号時間との最適設計に必要である。すなわち、ドット形状が正確に再現できる印字物に関しては、復号は容易であると判断し、復号時間の速い復号方法を用いる。一方、ドット形状の再現性が悪く、フェザリングを起こしていると想定される印字物に関しては、復号時間よりも復号検出率を優先にして、より精度の高い復号方法を用いる。
【０１００】
このように、記録した印字物の紙種を評価因子にすることにより、印字品位が予測することができ、より最適な復号手段を選択することができる。
【０１０１】
本実施形態では、復号部をＡ、Ｂの２種にて説明したが、当然これ以上でも構わない。また、復号方法もこれに限定するものではない。
【０１０２】
また、復号部を同一にして、その検出精度だけを変化させる方法も考えられる。すなわち、より精度が求められる復号方法においては、冗長性の高い、繰り返しによる復号が有効である。例えば、前述のＰ×Ｑ画素による直交変換を用いる方法（復号部Ｂ）では、Ｐ×Ｑ画素のブロックを空間的に数画素ずらして複数回の直交変換を行い、複数回のクラス比較を通して判断の精度を高める方法が考えられる。その際に、経験的に記録媒体の物理特性をランク付けして評価因子として設定し、繰り返しの回数をランクに応じて徐々に増やす様に制御することも有効な方法である。
【０１０３】
当然、複数回の直交変換を用いて判断した方が、復号精度は向上するが、処理時間は余計にかかってしまう。その最適化は経験的に設計するのが好ましい。
【０１０４】
また、フェザリングの程度を予測して補正する方法も考えられる。すなわち、フェザリングによりドット径が広がり、隣接画素との間ににじみが生じる為、紙上では一種のＬＰＦの特性を有すると見なすことができる。そこで、ドット径の紙上での再現性を評価因子にして、経験的な補正値を算出して、ドット径補正をも含めた復号方法も考えられる。
【０１０５】
また、色材（インク）により紙上での物理特性が異なる場合には、復号処理に使用する色を変化する方法も考えられる。例えば、仮にマゼンタがインク濃度等の関係で他の色（シアン、イエロー、ブラック）よりもドット径が広がりやすい傾向があれば、ＲＧＢのうち、マゼンタの補色となるＧ成分からの復号影響度合いを変化させることも有効である。すなわち、紙上でのドット形状品位が良い紙種の場合には、Ｇ成分の復号を中心に判断して、ドット形状品位が悪くなるにつれ、Ｇ成分の復号の影響を減らして判断する方法である。
【０１０６】
また、紙種情報を埋め込み情報と付加せずに、実際に復号をする使用者がいかなる紙種かを判断して、キーボード、もしくはマウス等により入力しても良い。
【０１０７】
以上説明したように上記第１の実施形態によれば、記録媒体の種類に応じて画像に埋め込まれた所定の情報の抽出方法を切り替えるので、所定の情報の抽出精度、抽出時間の最適化、画質の最適設計を実現することができる。
【０１０８】
（第２の実施形態）
図１３は、第２の実施形態の画像処理システムの構成を示す。本実施形態は、図１に示した構成において、紙種情報に応じて多重化方法を変更するものである。
【０１０９】
図１３中、端子１００、１０１、１０２からは、それぞれ、画像情報、付加情報、紙種情報が入力される。１３０１、１３０２は、それぞれ、付加情報多重化部Ａ、付加情報多重化部Ｂを示し、２種の多重化部を有している。１３０３は、選択部を示し、紙種情報に応じて、スイッチ１３０４を介して、以下の選択がなされる。
１）紙種が光沢紙、もしくは、コート紙である場合 ・・・ 付加情報多重化部Aを選択
２）紙種が普通紙である場合 ・・・ 付加情報多重化部Ｂを選択
本実施形態では、付加情報多重化部Ａ、Ｂともに多重化の方法自体は図２と同様であり、多重化する際の条件のみを変更して区別する。前述した多重化方法は、誤差拡散法の量子化条件を周期的に変更することにより多重化している。前述した例では、図６（ａ）、及び（ｂ）に示したように、所定の周期性により量子化閾値を突出した値に変化させている。量子化閾値を周期的に変化させるということは、量子化閾値を振幅変調していることに相当する。
【０１１０】
本実施形態では、この振幅の値を付加情報多重化部A、及び、付加情報多重化部Ｂで異ならせる。
【０１１１】
図１４は、量子化閾値の変調する振幅を異ならせた一例を示す。図１４（ａ）が、付加情報多重化部Ａの振幅変調に相当し、図１４（ｂ）が、付加情報多重化部Ｂの振幅変調に相当する。量子化閾値の振幅は大きくなるに従って、変調をかけた所望の画素位置の量子化結果が制御できる。しかし、それに反して、変調の規則性により画質の劣化が生じてくる。そこで、ドット径の再現性の良い紙種の場合には、量子化閾値の振幅を小さくし、変調の規則性による画質の劣化を抑える様にする。但し、良質な紙の為、復号は容易である。
【０１１２】
一方、ドット径の再現性の悪い紙種の場合には、量子化閾値の振幅を大きくし、復号しやすいように量子化結果を制御する。但し、悪質な紙の為、フェザリング等のノイズが多くなり、変調の規則性による画質劣化は視覚的に目立たなくなる。
【０１１３】
また、付加情報多重化部を同一にして、その量子化閾値の振幅を変化させるようにしてもよい。
【０１１４】
以上、復号方法、多重化方法の切り替えについて説明してきたが、多重化方法、付加情報の分離方法は前述した方法に限定しない。いかなる、多重化方法、分離方法においても、紙種情報に基づいて分離方法、及び多重化方法を制御する構成は有効である。
【０１１５】
また、復号方法、多重化方法をそれぞれ独自に切り替える例について説明してきたが、当然、双方を連動して共に切り替える方法も効果がある。
【０１１６】
以上説明したように第２の実施形態によれば、記録媒体の種類に応じて画像に所定の情報を埋め込むための埋め込み方法を切り替えるので、画質、抽出精度の最適設計が実現することができる。
【０１１７】
また、本発明は、複数の機器（例えばホストコンピュータ、インタフェイス機器、リーダ、プリンタ等）から構成されるシステムに適用しても、一つの機器からなる装置（例えば、複写機、ファクシミリ装置等）に適用しても良い。
【０１１８】
また、本発明の目的は、前述した実施形態の機能を実現するソフトウエアのプログラムコードを記録した記憶媒体（または記録媒体）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、達成されることは言うまでもない。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。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働しているオペレーティングシステム（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。
【０１１９】
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カ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込まれた後、そのプログラムコードの指示に基づき、その機能拡張カードや機能拡張ユニットに備わるＣＰＵ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。
【０１２０】
【発明の効果】
以上説明したように、本発明によれば、記録媒体の種類に応じて画像に埋め込まれた所定の情報の抽出方法を切り替えるので、所定の情報の抽出精度、抽出時間の最適化、画質の最適設計を実現することができる。
【０１２１】
また、本発明によれば、記録媒体の種類に応じて画像に所定の情報を埋め込む埋め込み方法を切り替えるので、画質、抽出精度の最適設計が実現することができる。
【０１２２】
また、本発明によれば、容易に画像情報への付加情報の多重化が実現できる為、画像情報中に音声情報や秘匿情報を埋め込むサービス、アプリケーションが提供できる。また、紙幣、印紙、有価証券等の不正な偽造行為を抑制したり、画像情報の著作権侵害を防止したりすることができる。
【図面の簡単な説明】
【図１】第１の実施形態の画像処理システムを示す要部ブロック図
【図２】図１の埋め込み情報多重化装置を示す要部ブロック図
【図３】図２の誤差拡散法を示す要部ブロック図
【図４】量子化制御部を含む多重化処理の動作手順を示すフローチャート
【図５】ブロック化の一例
【図６】量子化条件における量子化閾値変化の一例
【図７】量子化条件の組み合わせの配置例
【図８】図１の埋め込み情報分離装置を示す要部ブロック図
【図９】図８の付加情報復号部Ａの構成を示すブロック図
【図１０】空間フィルタの一例
【図１１】図８の付加情報復号部Ｂの構成を示すブロック図
【図１２】二次元周波数領域での周波数ベクトルの説明図
【図１３】第２の実施形態における埋め込み情報分離装置を示す要部ブロック図
【図１４】量子化閾値の振幅変調の例
【図１５】従来法の多重化の一例を示すブロック図
【図１６】従来法の多重化の一例を示すブロック図
【図１７】従来法の多重化の一例を示すブロック図
【図１８】従来法の分離の一例を示すブロック図[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus and an image processing method, and in particular, in image information, information other than the image information, for example, voice information, text document information, various information about an image, completely different image information, and the like. As additional information, the present invention relates to image processing that is embedded in a visually inconspicuous manner.
[0002]
[Prior art]
Conventionally, research on multiplexing other information related to an image in image information has been actively conducted. In recent years, it has been referred to as digital watermarking technology. In image information such as photographs and paintings, additional information such as the author's name and permission to use is multiplexed so that it is difficult to visually distinguish them, and networks such as the Internet The technology distributed through is being standardized.
[0003]
Another application field is output from images output on paper to prevent unauthorized counterfeiting of banknotes, stamps, securities, etc. as image quality of image output devices such as copiers and printers increases. There is a technique for embedding additional information in an image in order to specify a device and its machine number.
[0004]
For example, Japanese Patent Laid-Open No. 7-123244 proposes a technique for multiplexing information by embedding additional information in a high-frequency region of a color difference component and a saturation component that are visually low in sensitivity.
[0005]
However, the technique described above has the following problems. FIG. 15 is a diagram showing embedding of general additional information in the digital watermark technique. Image information A and additional information B are multiplexed via an adder 1501 and changed to multiplexed information C. FIG. 15 shows an example in which additional information is multiplexed in the real space area of image information. If it is possible to distribute this multiplexed information C without performing various image processing such as filtering or encoding such as lossy compression, it is possible to decode the additional information B from the multiplexed information C even in the prior art. Easy. Image information distributed on the Internet can be decoded through a digital filter for improving image quality such as edge enhancement and smoothing if it has some noise tolerance.
[0006]
However, it is assumed that the multiplexed image is printed by an output device such as a printer, and additional information is extracted from the printed matter. In addition, a printer output is assumed in which the printer to be used has an expression capability of about 2 to several gradations per single color. In recent years, inkjet printers have been launched on the market that can display several gradations per single color by using ink with a low dye concentration or variably controlling the output dot diameter. Unless tone is used, the gradation of a photographic image cannot be expressed.
[0007]
That is, in the above-described assumption that the multiplexing method using the digital watermark technique of FIG. 15 is output to the printer, as shown in FIG. 16, the multiplexed information C is converted into the quantized information D by the pseudo gradation processing unit 1601. After that, by printing on the paper by the printer output unit 1602, the information changes to paper information (printed matter), which is very deteriorated E. Therefore, decoding additional information from information on paper for the purpose of preventing forgery described above means decoding additional information B from on-paper information E after a series of processing in FIG. The amount of change in information by both processes 1601 and 1602 is very large, and it is very difficult to multiplex additional information so that it cannot be visually discriminated and to correctly decode the multiplexed additional information from the paper. become.
[0008]
FIG. 17 shows an example of a conventional digital watermark technique in which image information is converted into a frequency domain using a Fourier transform or the like instead of the real space domain and then synthesized into a high frequency area or the like. In FIG. 17, image information is converted into a frequency domain by an orthogonal transformation processing unit 1701, and additional information is added by a adder 1702 to a specific frequency that is difficult to visually distinguish. After returning to the real space area again by the 1703 inverse orthogonal transform processing unit, this corresponds to passing through a filter with a large change such as a pseudo gradation processing unit and a printer output unit, as in the example of FIG.
[0009]
FIG. 18 shows a process of separating additional information from the paper. That is, information on the printed matter is input via the image reading unit 1801 such as a scanner. Since the input information is an image whose gradation is expressed by the pseudo gradation processing unit, a restoration processing unit 1802 which is an inverse pseudo gradation processing unit is applied. The restoration process generally uses an LPF (low pass filter). After the restored information is orthogonally transformed by 1803, the 1804 separation processing unit separates the additional information embedded from the power of a specific frequency.
[0010]
As is apparent from FIGS. 17 and 18 described above, it can be seen that a large number of complicated processing steps are passed from the multiplexing of the additional information to the separation. In the case of a color image, this series of processing steps includes a color conversion process for converting to a color unique to the printer. In order to achieve good separation even in such a complicated processing step, a very strong signal must be input. It is difficult to input a strong signal while maintaining good image quality. In addition, the large number of processing steps and the complexity make the processing time required for multiplexing and separation very long.
[0011]
Further, in the above-mentioned Japanese Patent Laid-Open No. 7-123244, information is added to the high frequency region. However, when the error diffusion method is performed in the pseudo gradation processing in the subsequent stage, the high-pass filter characteristic unique to the error diffusion method The additional information band is buried in the texture band generated by error diffusion, and there is a possibility that decoding may fail. In addition, a highly accurate scanner device is required for decoding. In other words, it is understood that the methods shown in FIGS. 16 and 17 are not suitable when pseudo gradation processing is assumed. In other words, a method of multiplexing additional information that greatly utilizes the characteristics of pseudo gradation processing is required.
[0012]
Special registration 2640939 and special registration 2777800 are examples in which multiplexing of additional information is combined with redundancy of pseudo gradation processing.
[0013]
In the former, when binarization is performed by the systematic dither method, data is mixed in the image signal by selecting one of the dither matrices representing the same gradation.
[0014]
However, with the systematic dither method, it is difficult to output a photographic image with high image quality unless the printer has high resolution and excellent mechanical accuracy. This is because a slight deviation in mechanical accuracy occurs as low-frequency noise such as horizontal stripes and is easily visible on paper. In addition, when the dither matrix is periodically changed, a band of a specific frequency generated by the regularly arranged dither is disturbed, which adversely affects image quality.
[0015]
Also, the gradation expression ability varies greatly depending on the type of dither matrix. Particularly on paper, since the change in area ratio due to dot overlap or the like varies depending on the dither matrix, it may be possible to cause a change in density by switching the dither matrix even in a region having a uniform density on the signal. In addition, for the decoding (separation) side, a decoding method that estimates what dither matrix is used for binarization while the pixel value of the image information that is the original signal is unknown may cause erroneous decoding. Very big.
[0016]
The latter is a method of multiplexing additional information according to the arrangement using a color dither pattern method. In this method, as in the former case, image quality deterioration cannot be avoided by switching. In addition, as compared with the former, more additional information can be multiplexed, but color change is caused by changing the arrangement of the color components, and image quality deterioration is particularly large in a flat portion. Also, it is expected that decoding on paper will become even more difficult.
[0017]
In any case, both methods of changing the dither matrix have a problem that decoding is difficult although image quality deterioration is large.
[0018]
Therefore, the applicant of the present invention first uses the texture generated by the error diffusion method to embed the code by artificially creating a combination of quantized values that cannot be generated by normal pseudo gradation processing. Proposed way to do.
[0019]
In this method, the texture shape only slightly changes microscopically, so that the image quality is not visually deteriorated. In addition, if a method for changing the quantization threshold of the error diffusion method is used, the density value of the area gradation is visually maintained, so that multiplexing of different signals can be realized very easily.
[0020]
However, according to the above proposal, the decoding side must determine whether the texture is artificial or not. In the printed matter output on the paper, the texture may not be reproduced well due to a deviation from a desired landing point position such as a warp of dots.
[0021]
In color images, the method of multiplexing to the color component with the lowest visual sensitivity is the mainstream, but the texture discrimination in the real space region is easily influenced by other color components, and the multiplexing information Separation becomes difficult.
[0022]
In addition, in order to solve the above-described problems, the present applicant performs amplitude modulation on the quantization threshold of the error diffusion method with a predetermined periodicity, and controls a plurality of types of the periodicity of the threshold modulation for each region. Proposed a method of embedding codes based on this periodicity by controlling the generation probability of the quantization value of pseudo gradation processing.
[0023]
In this method, since the relative power information in a plurality of predetermined frequency bands is an important decoding factor rather than the phase information forming the code, compared to the method of determining the position and shape of the texture described above, Good decoding can be realized even on paper.
[0024]
[Problems to be solved by the invention]
However, the above proposal has the following problems.
[0025]
That is, when considering a decoding process that separates additional information from a printed matter, decoding may be difficult depending on the printed recording medium.
[0026]
Now, consider an inkjet printer as the target of the printer. Recording media that can be used by an ink jet printer are roughly classified into glossy paper, coated paper, plain paper, OHP paper, and ink jet postcards that are also used in New Year's card postcards and government postcards in recent years. Naturally, even if glossy paper, coated paper, etc. are classified, their quality and characteristics are diverse.
[0027]
In glossy paper and coated paper, the ink droplets on the paper often show an accurate dot shape. However, in the above-mentioned inkjet postcards and plain paper, etc., the dot shape is crushed and the dot diameter is distorted along the fiber of the paper. A phenomenon called a ring occurs.
[0028]
Further, deterioration of printed matter such as fading and discoloration varies greatly depending on the recording medium.
[0029]
That is, according to the conventional method, the printed material produced on any recording medium has to be decoded by the same decoding method without considering the characteristics of the recording medium, although the quality of the printed material is different. That is, it has not been possible to propose a decoding system capable of realizing the optimum design of the detection accuracy and decoding processing time of the additional information in the decoding process.
[0030]
The same applies to multiplexing of additional information. Depending on the type of paper to be used, the visual conspicuousness of image quality deterioration due to the addition is different, and the extraction accuracy is different when the same decoding method is used. That is, it has not been possible to propose a multiplexing system that can realize image quality control in multiplexing and optimum design of detection accuracy.
[0031]
The present invention has been made to solve the above-described problem, and is an image processing apparatus capable of realizing detection (extraction) accuracy of additional information embedded in an image, optimization of extraction time, and optimum design of image quality. And an image processing method.
[0032]
Another object of the present invention is to provide an image processing apparatus and an image processing method capable of realizing image quality control when embedding additional information in an image and optimal design of detection (extraction) accuracy.
[0033]
[Means for Solving the Problems]
In order to achieve the above object, an image processing apparatus of the present invention comprises an image input unit that reads a recording medium on which an image in which predetermined information is embedded is formed and inputs an image corresponding to the recorded matter, and the input Information input means for extracting and inputting information on the type of the recording medium embedded in the image from the input image, extraction means for extracting the predetermined information from the input image according to a predetermined extraction method, and having a switching means for switching the extraction method by the extraction means based on the input information.
[0034]
In order to achieve the above object, an image processing method of the present invention includes an image input step of reading a recording medium on which an image in which predetermined information is embedded is formed and inputting an image corresponding to the recorded matter; An information input step of extracting and inputting information on the type of the recording medium embedded in the image from the input image, and an extraction step of extracting the predetermined information from the input image according to a predetermined extraction method When, and having a switching means for switching the extraction method by the extraction step based on the input information.
[0035]
In order to achieve the above object, an image image processing apparatus according to the present invention includes an image input unit for inputting an image, an input unit for inputting predetermined information to be embedded in the image, and a recording medium on which the image is formed. An information input means for inputting information relating to the type of the image , an embedding means for embedding the inputted predetermined information and the information relating to the type of the recording medium in accordance with a predetermined embedding method for the inputted image, And switching means for switching an embedding method by the embedding means based on inputted information.
[0036]
In order to achieve the above object, the image processing method of the present invention includes an image input step of inputting an image, a step of inputting predetermined information to be embedded in the image, and information relating to the type of recording medium on which the image is formed. An information input step, an embedding step of embedding the input predetermined information and information on the type of the recording medium in accordance with a predetermined embedding method for the input image , and the input information And a switching step of switching the embedding method in the embedding step based on the above.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment according to the present invention will be described in detail with reference to the drawings. The image processing apparatus according to the present embodiment is efficiently incorporated mainly as printer driver software or application software in a computer that creates image information to be output to the printer engine. It is also effective to incorporate the printer main body as hardware and software.
[0038]
(First embodiment)
FIG. 1 is a block diagram illustrating a configuration of an image processing system according to the first embodiment.
[0039]
Reference numerals 100, 101, and 102 denote input terminals. From 100, multi-tone image information is input, and from 101, necessary additional information to be embedded in the image information is input. This additional information is information different from the image information input at the input terminal 100, for example, voice information, text document information, copyright relating to the image input at the input terminal 100, shooting date / time, shooting location, shooting. Various applications such as various information on the person and completely different image information can be considered.
[0040]
From 102, information relating to the type of recording medium that is a printed matter (hereinafter referred to as paper type information) is input. In this embodiment, paper type information is added as header information in addition to the additional information described above. The paper type information may be input by a user using a keyboard or a mouse, or may be transmitted directly from a printer. Normally, printing with an inkjet printer or the like often has different color conversion parameters and printing processes depending on the paper type, so the user often specifies the paper type with the printer driver on the host computer. May be used.
[0041]
Reference numeral 103 denotes an embedding information multiplexing device that embeds paper type information and additional information (hereinafter, these two types are collectively referred to as embedding information) in image information so that it is difficult to visually discriminate. .
[0042]
The embedded information multiplexing apparatus 103 also controls the quantization of input multi-gradation image information as well as the multiplexing of embedded information.
[0043]
Reference numeral 104 denotes a printer, which outputs information created by the embedded information multiplexing apparatus 103 using a printer engine. The printer 104 is assumed to be a printer that realizes gradation expression by using pseudo gradation processing, such as an inkjet printer or a laser printer.
[0044]
The output printed matter reads information on the printed matter using the scanner 105, and the embedded information separating device 106 separates (extracts) the embedded information embedded in the printed matter and outputs it to the output terminal 107.
[0045]
FIG. 2 is a block diagram showing a configuration of the embedded information multiplexing apparatus 103 in FIG.
[0046]
Reference numeral 200 denotes an error diffusion processing unit, which converts the input image information into a quantization level smaller than the number of input gradations by performing pseudo gradation processing using an error diffusion method on the input image information. The gradation is expressed in terms of area by the conversion value. Details of the error diffusion processing will be described later.
[0047]
Reference numeral 201 denotes a blocking unit that divides input image information into predetermined area units. This blocking may be rectangular or may be divided into areas other than rectangular.
[0048]
Reference numeral 202 denotes a quantization condition control unit, which changes and controls the quantization condition in units of areas blocked by the blocking unit 201. The quantization condition control unit 202 controls the quantization condition in units of blocks based on the embedded information input from the input terminal 101.
[0049]
A control unit 210 includes a CPU 211, a ROM 212, a RAM 213, and the like. The CPU 211 controls the operation and processing of each component described above according to a control program held in the ROM 212. The RAM 213 is used as a work area for the CPU 211.
[0050]
FIG. 3 is a block diagram showing details of the error diffusion processing 200. General error diffusion processing is described in detail in the document R. Floyd & L. Steinberg: “An Adaptive Alogorithm for Spatial Grayscale”, SID Symposium Digest of Paper pp. 36-37 (1975).
[0051]
An error diffusion process in which the quantization value is binary will be described as an example. The quantized value is not limited to binary, but may be multivalued, for example, ternary or quaternary.
[0052]
Reference numeral 300 denotes an adder, which adds the target pixel value of the input image information and the distributed quantization error of the peripheral pixels already binarized. The comparison unit 301 compares the quantization threshold value from the quantization condition control unit 202 and the addition result obtained by adding the error. When the comparison value is larger than the predetermined threshold value, “1” is set. Otherwise, “0” is set. Output.
[0053]
For example, when expressing the gradation of a pixel with an accuracy of 8 bits, it is generally expressed by “255” as the maximum value and “0” as the minimum value. Now, it is assumed that when the quantized value is “1”, dots (ink, toner, etc.) are printed on paper.
[0054]
Reference numeral 302 denotes a subtracter that calculates an error between the quantization result and the above-described addition result, and distributes the error to surrounding pixels to be subjected to future quantization processing based on the error distribution calculation unit 303. As the error distribution ratio, an error distribution table 304 experimentally set based on the relative distance to the pixel of interest is previously owned, and the error is distributed based on the distribution ratio described in the distribution table.
[0055]
The distribution table 304 in FIG. 3 shows a distribution table for four surrounding pixels, but is not limited to this.
[0056]
Next, the entire operation procedure including the quantization condition control unit 202 will be described with reference to the flowchart of FIG. Now, an example in which the quantized value is binary will be described. The quantized value is not limited to binary, but may be multivalued, for example, ternary or quaternary.
[0057]
S401 indicates initialization of the variable i. The variable i is a variable for counting vertical addresses.
[0058]
S402 indicates initialization of the variable j. The variable j is a variable for counting horizontal addresses. Subsequently, S403 is a determination step based on the i and j address values, and it is determined whether or not the coordinates of i and j, which are the current processing addresses, belong to an area where the multiplexing process is to be executed.
[0059]
The multiplexed area will be described with reference to FIG. FIG. 5 shows one image having a horizontal pixel number of WIDTH and a vertical pixel number of HEIGHT.
[0060]
Assume that the embedded information is multiplexed in this image. The upper left of the image is set as the origin, and blocking is performed with N horizontal pixels and M vertical pixels. In the present embodiment, the origin is set as a reference point, but the block is set as a reference point. When the maximum information is multiplexed in this image, N × M blocks are arranged from the reference point. That is, when the number of blocks that can be arranged in the horizontal direction is W and the number of blocks that can be arranged in the vertical direction is H, the following relationship is established.
W = INT (WIDTH / N) ... Equation 1
H = INT (HEIGHT / M) ... Equation 2
However, INT () indicates an integer part in ().
[0061]
The number of remaining pixels that cannot be divided in Equations 1 and 2 corresponds to an end when a plurality of N × M blocks are arranged, and is outside the code multiplexing region.
[0062]
In FIG. 4, if it is determined in S403 that the pixel of interest currently being processed is outside the multiplexing region, the quantization condition C is set in S404. On the other hand, if it is determined that it is within the multiplexed area, the embedded information to be multiplexed is read. For ease of explanation, it is assumed that the embedded information is expressed bit by bit using an array called code []. For example, assuming that the paper type information is 8 bits and the additional information is 200 bits, the embedded information is 208 bits with two types added, and the array code [] is from code [0] to code [207]. Each one bit is stored. In S405, the variable bit is substituted with information in the array code [] as follows.
bit = code [INT (i / M) x W + INT (j / N)] ... Equation 3
Subsequently, it is determined whether or not the variable bit substituted in S406 is “1”. As described above, since information in the array code [] is stored one bit at a time, the value of the variable bit indicates either “0” or “1”. If “0” is determined in S406, the quantization condition A is set in S407, and if “1” is determined, the quantization condition B is set in S408.
[0063]
Subsequently, in S409, a quantization process is performed based on the set quantization condition. This quantization process corresponds to the error diffusion method described in FIG.
[0064]
Subsequently, in S410, the horizontal variable j is counted up, and in S411, it is determined whether or not it is less than WIDTH which is the number of horizontal pixels of the image, and the above-described processing is repeated until the number of processed pixels becomes WIDTH. When the horizontal processing is completed for the number of WIDTH pixels, the vertical direction variable i is counted up in S412, and it is determined in S413 whether or not it is less than HEIGHT which is the vertical pixel number of the image. Repeat the above process until.
[0065]
With the above operation procedure, the quantization condition can be changed in units of blocks each consisting of N × M pixels.
[0066]
Subsequently, examples of the quantization conditions A, B, and C will be described. Although there are various factors in the quantization condition in the error diffusion method, in this embodiment, the quantization condition is a quantization threshold. Since the use of the quantization condition C is outside the multiplexing region, any quantization threshold value may be used. As described above, when one pixel is represented by 8 bits of gradation and the quantization level is binary, the maximum value “255” and the minimum value “0” are the quantization representative value. However, “128” which is the intermediate value is often set as the quantization threshold. That is, in the quantization condition C, the quantization threshold value is fixed to “128”.
[0067]
Since the use of the quantization condition A and the quantization condition B is a block in the multiplexing region, a difference in image quality due to a difference in the quantization condition must be generated. However, the difference in image quality must be expressed so that it is difficult to distinguish visually, and it must be easily identifiable from the paper.
[0068]
FIG. 6 is an example showing the quantization conditions A and B. FIG. 6A is a diagram showing a cycle of change of the quantization threshold in the quantization condition A. In the figure, one square is assumed to be one pixel, a white square is a fixed threshold, and a gray square is a variation threshold. In other words, in the example of FIG. 6A, a matrix of 8 horizontal pixels and 4 vertical pixels is assembled, and a value that protrudes only from the gray square threshold is set as the threshold.
[0069]
Similarly, FIG. 6B is a diagram illustrating the period of change of the quantization threshold in the quantization condition B. In the example of FIG. 6B, unlike FIG. 6A, a matrix of 4 horizontal pixels and 8 vertical pixels is assembled, and a value that protrudes only from a gray square threshold is set as the threshold.
[0070]
As described above, when one pixel has an 8-bit gradation value as described above, for example, “128” is set as the fixed threshold value, and “48” is set as the protruding threshold value. When the quantization threshold is lowered, the quantization value of the target pixel tends to be “1” (quantization representative value “255”).
[0071]
That is, in both FIGS. 6A and 6B, the quantized value “1” is likely to occur due to the arrangement of gray cells in the figure. In other words, for each N × M pixel block, there are a block in which dots are generated in the arrangement of gray squares in FIG. 6A and a block in which dots are generated in the arrangement of gray squares in FIG. 6B. Will be mixed. Naturally, the matrix shown in FIG. 6A or 6B is repeated in the same block of N × M pixels.
[0072]
A slight change in the quantization threshold in the error diffusion method does not have a significant effect on image quality. In the systematic dither method, the image quality of gradation expression greatly depends on the dither pattern used.
[0073]
However, in the error diffusion method in which the quantization threshold is regularly changed as described above, the gradation expression that determines the image quality is the error diffusion method, so the dot arrangement may change slightly or the texture may change. The image quality of the gradation expression is hardly affected, such as occurrence changes. That is, even when the quantization threshold changes, the error that is the difference between the signal value and the quantized value is diffused to surrounding pixels, so that the input signal value is stored in a macro manner. In other words, the redundancy is very large with respect to dot arrangement and texture generation in the error diffusion method.
[0074]
In the above-described example, the switching is simply performed as the quantization condition A when the value of the variable bit is “0”, and as the quantization condition B when the value of the variable bit is “1”. However, the present invention is not limited to this. It is also possible to express the variable bit by a combination of quantization conditions.
[0075]
For example, as shown in FIG. 7, the N × M pixel block is further divided into four small blocks. When the value of the variable bit is “0”, the arrangement of FIG. It is also possible to make a difference by quantizing using the arrangement of FIG.
[0076]
Next, the embedded information separator 106 will be described.
[0077]
FIG. 8 is a block diagram illustrating a configuration of the embedded information separation device 106.
[0078]
Reference numeral 800 denotes an input terminal to which image information read by an image reading unit such as a scanner is input. The resolution of the scanner to be used is preferably equal to or higher than the resolution of the printer that creates the printed matter. Naturally, in order to accurately read dot dot information of a printed matter, the scanner side needs to have a resolution that is at least twice that of the printer side according to the sampling theorem. However, if it is equal to or greater than that, it is possible to determine that dots are scattered to some extent even if it is not accurate. In the present embodiment, for ease of explanation, it is assumed that the printer resolution and the scanner resolution are the same.
[0079]
Reference numeral 801 denotes a paper type information decoding unit that first decodes the paper type information, which is header information, of the embedded additional information. This decoding process preferably uses an additional information decoding unit B described later, but is not limited here. First, the header information is decoded.
[0080]
Reference numeral 802 denotes a selection unit. From the decoded paper type information, one of the additional information decoding unit A 803 and the additional information decoding unit B 804 is selected through the switch 805 as follows.
1) When the paper type is glossy paper or coated paper: Select the additional information decoding unit A 2) When the paper type is plain paper: Select the additional information decoding unit B 3 is a block diagram showing a configuration of an information decoding unit A. FIG.
[0081]
Reference numeral 901 denotes a blocking unit, which performs blocking in units of P × Q pixels. This block must be smaller than the N × M pixels that were blocked during multiplexing. That is,
P ≦ N and Q ≦ M ... Formula 5
The relationship holds.
[0082]
Further, the block formation in units of P × Q pixels is performed by skipping at certain intervals. That is, the block is formed so that one block of P × Q pixel unit is included in an area assumed to be a block of N × M pixels at the time of multiplexing. The number of skip pixels is basically N horizontal pixels and M vertical pixels.
[0083]
Reference numerals 902 and 903 denote spatial filters A and B having different characteristics, respectively, and reference numeral 904 denotes a digital filtering unit that calculates a product sum with peripheral pixels.
[0084]
Each coefficient of the spatial filter is created in conformity with the period of the variation threshold of the quantization condition at the time of multiplexing. Now, it is assumed that the quantization condition in the multiplexing apparatus is changed by multiplexing the additional information by using the two types of periodicity shown in FIGS. 6 (a) and 6 (b).
[0085]
Examples of the spatial filter A 902 and the spatial filter B 903 used in the embedded information separating apparatus 106 at that time are shown in FIGS. 10 (a) and 10 (b). In the figure, the central portion of 5 × 5 pixels is the pixel of interest, and the remaining 24 pixels are peripheral pixels. In the figure, the blank pixel represents that the filter coefficient is “0”. As is apparent from FIG. 10, FIGS. 10A and 10B are edge enhancement filters. In addition, the directionality of the emphasized edge matches the directionality of the variation threshold when multiplexed. That is, FIG. 10A is created to match FIG. 6A, and FIG. 10B is created to match FIG. 6B.
[0086]
Reference numeral 905 denotes a feature amount detection unit, which is a means for detecting some feature amount based on the converted values after filtering from the filtering unit 904 by the spatial filter A 902 and the spatial filter B 903. Examples of the feature amount to be detected are as follows.
1. 1. Maximum conversion value in the block after digital filter 2. Difference between maximum value and minimum value of converted value in block after digital filter In this embodiment, the variance value shown in 3 above is used as a feature value. Reference numeral 906 denotes a determination unit that compares the respective variance values and determines that the one with the larger variance value is a code. That is, if the dispersion value of filtering by the spatial filter A is large, it is estimated that the quantization is performed under the quantization condition A at the time of printing. I guess it was quantized with.
[0087]
Since the quantization condition is linked to the code of additional information (bit in Expression 3), the fact that the quantization condition can be identified corresponds to the ability to specify the multiplexed code. That is, when the quantization condition A is estimated, it can be determined that bit = 0, and when the quantization condition B is estimated, bit = 1.
[0088]
FIG. 11 is a block diagram showing the additional information decoding unit B.
[0089]
Reference numeral 1101 denotes a blocking unit, which is the same as 902 in FIG. 9 and blocks in units of P × Q pixels.
[0090]
Reference numeral 1102 denotes an orthogonal transformation unit, which is a means for orthogonally transforming the blocked P × Q pixels. However, when performing two-dimensional orthogonal transformation, it is necessary to block the square block with Q = P. In the present embodiment, DCT (Discrete Cosine Transform) is taken as an example.
The conversion coefficient of the two-dimensional DCT of the block consisting of P × P pixels is
[Outside 1]

[0091]
However, C (x) = 1 / √2 (x = 0),
C (x) = 1 (x ≠ 0) Expression 6
Given in.
[0092]
Reference numeral 1103 denotes a class classification unit which classifies each orthogonal transform coefficient band. FIG. 12 shows an example of class classification when P = Q = 16. FIG. 12 shows orthogonal transform coefficients F (u, v) in one block, with the upper left being a DC component and the remaining 255 components being an AC component.
[0093]
Now, two classes, class A centering on F (4,8) and class B centering on F (8,4), are created. Two classes are indicated by bold lines in the figure. This class classification means does not need to classify all 256 components, but only classifies them into a plurality of classes centering on the desired components. This required number of classes corresponds to the number of conditions that are quantized at the time of multiplexing. That is, the number of classes does not increase beyond the number of conditions subjected to quantization control.
[0094]
Reference numeral 1104 denotes a power comparison unit, which is a means for comparing the total power of each class. In order to speed up the calculation, the absolute value of the generated conversion coefficient may be used as a substitute for power. The signal of the additional information is determined by comparing the total power of each class.
[0095]
Now, an example in which the quantization conditions A and B of FIGS. 6A and 6B are applied at the time of multiplexing will be described. As described above, in the quantization using the quantization conditions A and B, a texture in which dots are arranged in oblique directions with different angles is likely to occur.
[0096]
That is, in the block quantized under the quantization condition A, when orthogonal transformation processing is performed, large power is generated in class A in FIG. On the other hand, in the block quantized under the quantization condition B, when orthogonal transformation processing is performed, large power is generated in class B in FIG.
[0097]
That is, it is determined whether the quantization condition at the time of multiplexing the corresponding block is the quantization condition A or the quantization condition B by relatively comparing the magnitude relationship between the power of class A and class B. it can. Since the quantization condition is linked to the code of additional information (bit in Expression 3), the fact that the quantization condition can be identified corresponds to the ability to specify the multiplexed code.
[0098]
In the example of the flowchart shown in FIG. 4, since bit = 0 is set to the quantization condition A and bit = 1 is set to the quantization condition B, when the power of class A is larger, bit = 0, If the power of class B is larger, it can be determined that bit = 1.
[0099]
Although two types of decoding units have been described above, switching of the decoding units according to the present embodiment is necessary for optimal design of the decoding detection rate and the decoding time. That is, it is determined that decoding is easy for a printed matter in which the dot shape can be accurately reproduced, and a decoding method with a fast decoding time is used. On the other hand, for a printed matter that is assumed to have poor dot shape reproducibility and cause feathering, a decoding method with higher accuracy is used with priority given to the decoding detection rate over decoding time.
[0100]
Thus, by using the paper type of the recorded printed matter as an evaluation factor, the print quality can be predicted, and a more optimal decoding means can be selected.
[0101]
In the present embodiment, the decoding unit has been described with two types of A and B, but naturally more than this may be used. Further, the decoding method is not limited to this.
[0102]
In addition, a method of changing the detection accuracy with the same decoding unit is also conceivable. That is, in a decoding method that requires higher accuracy, it is effective to perform decoding by repetition with high redundancy. For example, in the above-described method using orthogonal transformation using P × Q pixels (decoding unit B), a block of P × Q pixels is spatially shifted by several pixels, orthogonal transformation is performed a plurality of times, and determination is made through a plurality of class comparisons. A method for improving the accuracy of the above is conceivable. At that time, it is also an effective method to empirically rank the physical characteristics of the recording medium and set them as evaluation factors, and control the number of repetitions to gradually increase according to the rank.
[0103]
Of course, the determination using multiple orthogonal transforms improves the decoding accuracy, but requires more processing time. The optimization is preferably designed empirically.
[0104]
A method of predicting and correcting the degree of feathering is also conceivable. That is, the dot diameter increases due to feathering and blurring occurs between adjacent pixels, so that it can be regarded as having a kind of LPF characteristic on paper. Therefore, a decoding method including dot diameter correction by calculating empirical correction values using the reproducibility of the dot diameter on paper as an evaluation factor is also conceivable.
[0105]
Further, when the physical characteristics on paper differ depending on the color material (ink), a method of changing the color used for the decoding process is also conceivable. For example, if magenta tends to have a larger dot diameter than other colors (cyan, yellow, black) due to ink density, etc., the degree of decoding influence from the G component that is the complementary color of magenta in RGB is set. It is also effective to change. In other words, in the case of a paper type with good dot shape quality on paper, the determination is made centering on the decoding of the G component, and as the dot shape quality deteriorates, the influence of the decoding of the G component is reduced. .
[0106]
Further, without adding the paper type information to the embedded information, the user who actually performs decoding may determine what type of paper it is and input it using a keyboard or a mouse.
[0107]
As described above, according to the first embodiment, since the extraction method of the predetermined information embedded in the image is switched according to the type of the recording medium, the extraction accuracy of the predetermined information, the optimization of the extraction time, Optimal design for image quality can be realized.
[0108]
(Second Embodiment)
FIG. 13 shows the configuration of the image processing system of the second embodiment. In the present embodiment, the multiplexing method is changed according to the paper type information in the configuration shown in FIG.
[0109]
In FIG. 13, image information, additional information, and paper type information are input from terminals 100, 101, and 102, respectively. Reference numerals 1301 and 1302 denote an additional information multiplexing unit A and an additional information multiplexing unit B, respectively, and have two types of multiplexing units. Reference numeral 1303 denotes a selection unit, and the following selection is made via the switch 1304 according to the paper type information.
1) When the paper type is glossy paper or coated paper: Select the additional information multiplexing unit A 2) When the paper type is plain paper: Select the additional information multiplexing unit B Then, both the additional information multiplexing units A and B are multiplexed in the same manner as in FIG. 2, and only the conditions for multiplexing are changed for distinction. The multiplexing method described above is multiplexed by periodically changing the quantization condition of the error diffusion method. In the above-described example, as shown in FIGS. 6A and 6B, the quantization threshold is changed to a prominent value with a predetermined periodicity. Changing the quantization threshold periodically corresponds to amplitude modulation of the quantization threshold.
[0110]
In the present embodiment, the value of the amplitude is made different between the additional information multiplexing unit A and the additional information multiplexing unit B.
[0111]
FIG. 14 shows an example in which the amplitude for modulating the quantization threshold is varied. 14A corresponds to the amplitude modulation of the additional information multiplexing unit A, and FIG. 14B corresponds to the amplitude modulation of the additional information multiplexing unit B. As the amplitude of the quantization threshold increases, the quantization result of a desired pixel position subjected to modulation can be controlled. However, on the other hand, the image quality is degraded due to the regularity of the modulation. Therefore, in the case of a paper type with a good dot diameter reproducibility, the amplitude of the quantization threshold is reduced to suppress deterioration in image quality due to modulation regularity. However, decoding is easy because of high-quality paper.
[0112]
On the other hand, in the case of a paper type with poor dot diameter reproducibility, the quantization threshold amplitude is increased, and the quantization result is controlled so that decoding is easy. However, because of vicious paper, noise such as feathering increases, and image quality degradation due to modulation regularity is not visually noticeable.
[0113]
Further, the additional information multiplexing unit may be the same, and the amplitude of the quantization threshold may be changed.
[0114]
The switching between the decoding method and the multiplexing method has been described above, but the multiplexing method and the additional information separation method are not limited to the methods described above. In any multiplexing method and separation method, a configuration for controlling the separation method and the multiplexing method based on the paper type information is effective.
[0115]
Moreover, although the example which switches a decoding method and a multiplexing method each independently was demonstrated, naturally the method of switching both together interlockingly has an effect.
[0116]
As described above, according to the second embodiment, since an embedding method for embedding predetermined information in an image is switched according to the type of recording medium, an optimum design of image quality and extraction accuracy can be realized.
[0117]
In addition, the present invention can be applied to a system composed of a plurality of devices (for example, a host computer, interface device, reader, printer, etc.), or a device (for example, a copier, a facsimile device, etc.) composed of a single device. You may apply to.
[0118]
Another object of the present invention is to supply a storage medium (or recording medium) that records software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and to perform a computer (or CPU) of the system or apparatus. Needless to say, this can also be achieved by reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.
[0119]
Further, after the program code read from the storage medium is written in a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that the CPU or the like provided in the card or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.
[0120]
【The invention's effect】
As described above, according to the present invention, since the extraction method of the predetermined information embedded in the image is switched according to the type of the recording medium, the extraction accuracy of the predetermined information, the optimization of the extraction time, the optimization of the image quality Design can be realized.
[0121]
Furthermore, according to the present invention, the embedding method for embedding predetermined information in an image is switched according to the type of recording medium, so that an optimum design of image quality and extraction accuracy can be realized.
[0122]
Further, according to the present invention, since additional information can be easily multiplexed with image information, services and applications for embedding audio information and confidential information in image information can be provided. In addition, illegal counterfeiting such as banknotes, stamps, and securities can be suppressed, and copyright infringement of image information can be prevented.
[Brief description of the drawings]
FIG. 1 is a principal block diagram showing an image processing system of a first embodiment. FIG. 2 is a principal block diagram showing an embedded information multiplexing apparatus of FIG. 1. FIG. 3 is a principal diagram showing an error diffusion method of FIG. FIG. 4 is a flowchart showing an operation procedure of a multiplexing process including a quantization control unit. FIG. 5 is an example of blocking. FIG. 6 is an example of a quantization threshold change under a quantization condition. Arrangement example of combination of conditions [FIG. 8] Block diagram of main part showing embedded information separating apparatus of FIG. 1 [FIG. 9] Block diagram showing configuration of additional information decoding unit A of FIG. 11 is a block diagram showing the configuration of the additional information decoding unit B in FIG. 8. FIG. 12 is an explanatory diagram of frequency vectors in a two-dimensional frequency domain. FIG. 13 is a main part showing an embedded information separating apparatus in the second embodiment. Block diagram [Figure 14] Quantization threshold Example of amplitude modulation FIG. 15 is a block diagram showing an example of conventional multiplexing. FIG. 16 is a block diagram showing an example of conventional multiplexing. FIG. 17 is a block diagram showing an example of conventional multiplexing. FIG. 18 is a block diagram showing an example of separation in the conventional method

Claims (18)

An image input means for reading a recording medium on which an image in which predetermined information is embedded is formed and inputting an image corresponding to the recorded matter;
Information input means for extracting and inputting information on the type of the recording medium embedded in the image from the input image ;
Extraction means for extracting the predetermined information from the input image according to a predetermined extraction method;
An image processing apparatus comprising: a switching unit that switches an extraction method by the extraction unit based on the input information.   The image processing apparatus according to claim 1, wherein the information regarding the type of the recording medium is information indicating glossy paper.   The image processing apparatus according to claim 1, wherein the information regarding the type of the recording medium is information indicating coated paper.   The image processing apparatus according to claim 1, wherein the information regarding the type of the recording medium is information indicating plain paper.   2. The switching unit according to claim 1, wherein the switching unit selects an optimum extraction unit from a plurality of extraction units each having a different extraction method, and switches the extraction method by performing extraction using the selected extraction unit. Image processing device.   The image processing apparatus according to claim 1, wherein the switching unit switches the extraction method by switching an extraction accuracy when extracting the predetermined information. An image input means for inputting an image;
Input means for inputting predetermined information to be embedded in the image;
Information input means for inputting information relating to the type of recording medium on which the image is formed;
Embedding means for embedding the input predetermined information and information regarding the type of the recording medium in accordance with a predetermined embedding method for the input image;
An image processing apparatus comprising: a switching unit that switches an embedding method by the embedding unit based on the input information.   8. The image processing apparatus according to claim 7, wherein the information regarding the type of the recording medium is information indicating glossy paper.   8. The image processing apparatus according to claim 7, wherein the information regarding the type of the recording medium is information indicating coated paper.   8. The image processing apparatus according to claim 7, wherein the information relating to the type of the recording medium is information indicating plain paper.   8. The switching unit according to claim 7, wherein the switching unit selects an optimal embedding unit from a plurality of embedding units each having a different embedding method, and switches the embedding method by performing embedding by the selected embedding unit. Image processing device.   8. The image processing apparatus according to claim 7, wherein the switching unit switches the embedding method by switching embedding accuracy when embedding is performed by the embedding unit. An image input step of reading a recording medium on which an image in which predetermined information is embedded is formed and inputting an image corresponding to the recorded matter;
An information input step of extracting and inputting information on the type of the recording medium embedded in the image from the input image ;
An extraction step of extracting the predetermined information from the input image according to a predetermined extraction method;
An image processing method comprising: switching means for switching an extraction method in the extraction step based on the input information. An image input process for inputting an image;
A step of inputting predetermined information to be embedded in the image, and an information input step of inputting information on the type of recording medium on which the image is formed;
An embedding step of embedding the input predetermined information and information on the type of the recording medium in accordance with a predetermined embedding method for the input image;
An image processing method comprising: a switching step of switching an embedding method in the embedding step based on the input information.   A program for realizing the image processing method according to claim 13 by being executed on a computer.   The program which implement | achieves the image processing method of Claim 14 by being performed on a computer.   A recording medium on which the program according to claim 15 is recorded.   A recording medium on which the program according to claim 16 is recorded.

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