JP2009111984A - Information processing apparatus and method, computer program and computer-readable recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information embedding technique that enables embedding of watermark information which manipulates placement of constituent images, in electronic document data, as well as, extraction of the embedded watermark information from among printed documents. <P>SOLUTION: The present invention relates to a watermark information embedding apparatus which generates a document image from electronic document data A that have been inputted thereto, modifies the electronic document data A, based on the document image and embeds information in the electronic document data. The apparatus includes a document image generator 102 for generating a document image from the electronic document data A; a document analyzer 103 for detecting layout information of each constituent image in the generated document image; a normalization information calculating unit 104 for calculating normalization information, which is for normalizing the placement of each constituent image, based on the detected layout information; a modification unit 105 for modifying the electronic document data A, based on the calculated normalization information; and an embedding unit 107 for embedding information in the modified electronic document data A. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for embedding information in a document.

  A technique for embedding information in a document and extracting the embedded information (generally called watermark information) is useful for improving the security of the document.

  For example, watermark information is embedded in the document image by adjusting the arrangement position of the character image, and the document image is output as a print document. The output print document is captured by a scanner or the like, and watermark information is extracted from the document image as a document image (Patent Document 1). This technique has copy resistance because the arrangement position of the character image is not easily changed by copying.

On the other hand, after changing the arrangement information of electronic document data including text described by page description and embedding watermark information, the watermark information is extracted from the electronic document data (Patent Document 2). Here, the electronic document data described in the page is a language for instructing the printer to output. Characters, graphics, and the like can be printed with optimum character quality and image quality according to each printer, and are used in general laser printers. In the technique of Patent Document 1, since watermark information is embedded in a document image, it cannot be printed with an optimum character quality or image quality. Therefore, it is considered necessary to embed the electronic document data described in the page.
JP 2005-253004 A JP 2000-99501 A

  However, the technique of Patent Document 1 embeds watermark information on a document image, and conversion from a document image to electronic document data is necessary to output it as electronic document data. When this conversion is performed, block selection, optical character recognition (hereinafter referred to as OCR), etc. are performed, but the character spacing changes due to an error due to OCR or the effect of hinting processing that improves the character quality during outline font drawing processing. It may end up. For this reason, there is a case where the embedded watermark information cannot be correctly extracted from the watermark information embedded in the document image and the electronic data converted after the embedding. In addition, the amount of processing of the conversion is large.

  On the other hand, since the technique of Patent Document 2 embeds watermark information on electronic document data, when it is output as a print document, the same watermark as the watermark information embedded in the electronic document data on the document image In many cases, information cannot be extracted.

  Therefore, an object of the present invention is to provide an information embedding technique capable of embedding watermark information for manipulating the arrangement of constituent images in electronic document data and extracting the embedded watermark information from the printed document. It is in.

  In order to solve the above-described problems, an information processing apparatus according to the present invention is an information processing apparatus that embeds information in input electronic document data, and includes an image generation unit that generates a document image from the electronic document data, and the generation Detection means for detecting layout information of each component image in the document image, and calculation means for calculating normalization information for normalizing the arrangement of each component image based on the detected layout information; Embedding means for changing the electronic document data based on the calculated normalization information and embedding information in the changed electronic document data.

  An information processing method according to the present invention is an information processing method for embedding information in input electronic document data, and includes an image generation step of generating a document image from the electronic document data, and the generated document image A detection step of detecting layout information of each component image, a calculation step of calculating normalization information for normalizing each component image based on the detected layout information, and the calculated normalization information And changing the electronic document data and embedding information in the changed electronic document data.

  According to the present invention, it is possible to provide an information embedding technique capable of embedding watermark information for manipulating the arrangement of constituent images in electronic document data and extracting the embedded watermark information from the printed document. .

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is a conceptual configuration diagram of a watermark information embedding device 100 according to the first embodiment and the second embodiment of the present invention.

  The watermark information embedding device (information processing device) 100 generates a document image from the input electronic document data A, changes the electronic document data A based on the document image, and embeds the watermark information B in the electronic document data A. Device. The document image is image data including characters (for example, bitmap format data), and the electronic document data is other text data. The watermark information embedding device 100 has an electronic document data input unit 101 for inputting electronic document data (hereinafter referred to as page description data) A described in a page. The document image generation unit 102 generates a document image from the page description data A input by the electronic document data input unit 101. The document analysis unit 103 also detects layout information regarding the circumscribed rectangle of each character image in the document image generated by the document image generation unit 102. The document image generation unit 102 generates a document image with a resolution that allows the document analysis unit 103 to detect layout information. In addition, based on the layout information detected by the document analysis unit 103, the interval between the circumscribed rectangle to be noticed (hereinafter referred to as the noticed rectangle) and the circumscribed rectangle adjacent to the noticed rectangle is normalized. A normalization information calculation unit 104 that calculates normalization information is included.

  Further, the electronic document data input by the electronic document data input unit 101 is changed by the changing unit 105 based on the normalization information. Further, the watermark information input unit 106 for inputting the watermark information B and the watermark information B by adjusting the normalized interval on the electronic document data based on the watermark information B input from the watermark information input unit 106. Embedded portion 107 is embedded. Furthermore, an output unit 108 that outputs as an embedded document print C in which the watermark information B is embedded is provided.

  FIG. 2 is a flowchart showing an operation procedure of the watermark information embedding device 100 according to the first and second embodiments, and FIG. 3 is a diagram showing an example of a set of character intervals.

  First, in step S 201, page description data A is input to the electronic document data input unit 101. The page description data A is data for instructing the printer to perform drawing or for displaying on the monitor. Examples thereof include PS (Post Script), XPS (XML Paper Specification), and PDF (Portable Document Format). Although an example of page description data is shown here, the present invention can also be applied to electronic document data other than page description data, for example, a text file.

  In step S202, the document image generation unit 102 generates a document image from the page description data A. If the normalization information can be calculated without error, the resolution of the document image may be lower than the standard resolution at the time of generation. As a result, the processing speed can be increased and the area for storing images can be reduced. For example, the resolution create_dpi at the time of generation can be set as follows. First, a document image is generated from some page description data, and a character spacing minimum value space_min described below is obtained. The lowest resolution that can be set equal to or higher than the prescribed resolution order_dpi divided by space_min is defined as the resolution create_dpi at the time of generation. That is, if order_dpi is 600 and space_min is 4, create_dpi is 600/4 = 150 dpi. In this method, the minimum character spacing does not disappear due to the reduction and cannot be grasped. Therefore, normalization information can be calculated without error.

  In step S203, a circumscribed rectangle (character area) is detected from the generated document image. The circumscribed rectangle is a rectangle circumscribing the character as shown in FIG. The circumscribed rectangle originally indicates an area where character recognition is performed. In the watermark information technique, the circumscribed rectangle indicates a character area to be embedded.

  When detecting a circumscribed rectangle, first, each pixel value of the document image is projected onto the vertical coordinate axis, and a line is divided by searching for a blank portion (a portion without a black character) to determine a row. . Thereafter, the document image is projected on the horizontal coordinate axis line by line, and a blank portion is searched and divided into characters. Thereby, each character can be cut out by a circumscribed rectangle, and the circumscribed rectangle can be detected.

  When the circumscribed rectangle is detected in this way, the character spacing of the document image is calculated from the circumscribed rectangle in step S204. Note that the character spacing is, for example, the spacing between the target rectangle and the circumscribed rectangle adjacent to the target rectangle, as indicated by P or S in FIG. After that, based on the character spacing calculated in step S204, normalization information for normalizing the character spacing is calculated in step S205. Details of step S205 will be described later.

  In step S206, the page description data is changed based on the normalization information calculated in step 205. Details of step S206 will be described later. In step S207, the watermark information B to be embedded is input from the watermark information input unit 106, and the watermark information B is embedded by adjusting the character spacing on the changed page description data. Details of step S207 will be described later.

  Finally, in step S208, the embedded document printed matter C in which the watermark information B is embedded is output.

[Normalized information calculation unit 104 (step S205)]
FIG. 4 is a flowchart showing an operation procedure of the normalized information calculation unit 104 according to the first embodiment. Processing in the normalization information calculation unit 104 includes a target rectangle, a circumscribed rectangle adjacent to the target rectangle (hereinafter referred to as a front rectangle), and a circumscribed rectangle adjacent to the rear of the target rectangle (hereinafter referred to as a rear rectangle). )), Adjust the character spacing. Note that, as shown in FIG. 3, the character interval between the target rectangle and the front rectangle is P, and the character interval between the target rectangle and the rear rectangle is S.

  First, in step S205a, a pair P and S of character intervals before and after adjacent to the target rectangle are selected. For example, when the number of circumscribed rectangles in a line is 30 (however, the number of characters is not necessarily 30), P and S exclude the circumscribed rectangles at both ends of the line, and even-numbered Focus on the circumscribed rectangle.

  In the page description data A input from the electronic document data input unit 101, the distance to the next character corresponding to the above-described character spacing P, S and the character spacing on the page description data can be manipulated. And Note that A0 and B0 are expressed in numerical form in the page description data 601 as shown in FIG. 6, for example. FIG. 14 shows the correspondence between characters and A0 and B0. As shown in FIG. 14, for example, A0 indicates the distance from the drawing start position of “de” to the drawing start position of “di”, and the distance is 44 pixels. Depending on the type of page description data, it is not the distance to the next character, but the character spacing itself on the page description data. However, the present invention can be applied to any value that can manipulate the character spacing. Not too long.

  Next, in step S205b, it is determined whether or not the values of P and S are equal. If it is determined in step S205b that the values of P and S are equal, the process proceeds to step S205c. If it is determined that the values of P and S are not equal, the process proceeds to step S205d.

  In step S205c, the values of X and Y that are normalization information corresponding to the values A0 and B0 on the page description data are set to zero.

  In step S205d, an average value Z = (P + S) / 2 of the character spacings P and S is calculated. Note that in the character spacing of the page description data A, when the decimal part is not used, Z is subjected to processing such as rounding down or rounding up.

In step S205e, using the values of P and S and Z, X and Y are calculated as X = Z−P and Y = Z−S, respectively.
Finally, in step S205f, it is determined whether the target rectangle is the final circumscribed rectangle of the document image. If it is determined that the target rectangle is the final circumscribed rectangle, step S205 is ended. If it is determined that the target rectangle is not the final circumscribed rectangle, the process returns to step S205a.

[Change unit 105 (step S206)]
FIG. 5 is a flowchart showing an operation procedure of the changing unit 105 according to the first embodiment. The changing unit 105 changes the distance to the next character based on the calculated normalization information. As a result, the character spacing on the page description data is normalized.

  First, in step S206a, distances A0 and B0 to the next character, which is character information corresponding to the adjacent character spacing sets P and S, are selected.

  Next, in step S206b, the distances A1 and B1 to the next character after the change are calculated as A1 = A0 + α × X and B1 = B0 + α × Y, and the data content is changed. Here, α may be a preset value or a newly input value that is a coefficient for associating the document image with the page description data.

  Finally, in step S206c, it is determined whether or not the character information corresponding to P and S is the last. If it is determined in step S206c that the character information is the last, step S206 is ended. If it is determined that the character information is not the last, the process returns to step S206a.

  As described above, since the character spacing is normalized, it is possible to embed even if character spacing information cannot be obtained from the page description data.

[Embedding unit 107 (step S207)]
FIG. 15 is a flowchart showing an operation procedure of the embedding unit 107 according to the first embodiment. The embedding unit 107 operates the size relationship between adjacent character intervals on the page description data using the distance to the next character, and inserts the watermark information B into the page description data A.

  First, in step S207a, distances A1 and B1 to the next character are selected. In step S207b, a watermark bit to be embedded is selected from the bit string of the watermark information B input from the watermark information input unit 106. In the present embodiment, the watermark information B is configured as a bit string of 0 or 1.

  Next, in step S207c, it is determined whether or not the watermark bit selected and embedded in step S207b is 1. If it is determined in step S207c that the embedded watermark bit is 1, in step S207d, the watermark information of the watermark information is set so that the character interval corresponding to A1 is larger than the character interval corresponding to B1. Perform embedding. That is, the distances A2 and B2 to the next character after embedding are calculated as A2 = A1 + γ and B2 = B2-γ, and watermark information is embedded. Here, γ is an arbitrary positive value.

  On the other hand, if it is determined in step S207c that the embedded watermark bit is not 1, that is, the embedded watermark bit is 0, the process proceeds to step S207e. Here, the watermark information is embedded so that the character interval corresponding to A1 is smaller than the character interval corresponding to B1. That is, the distances A2 and B2 to the next character after embedding are calculated as A2 = A1−γ and B2 = B2 + γ, and watermark information is embedded. In steps S207d and S207e, the increase / decrease of the distance to the next character was manipulated with an arbitrary positive value γ. As a result, the same effect as the operation of moving the target rectangle in the document image can be obtained.

  Thus, by adjusting the size relationship between adjacent character intervals on the page description data, 1-bit watermark information (0 or 1) is inserted for each set of character intervals. For example, when there are 30 characters in one line, 14-bit (= 30 / 2-1) watermark information B can be embedded.

  In this embodiment, the watermark information B is embedded in the page description data by adjusting the position of the even-numbered character. However, the position of the odd-numbered character is adjusted because it is not necessary to adjust the position with the adjacent character. By doing so, the watermark information B may be embedded in the page description data.

  In the present embodiment, the watermark information B is embedded every other character. That is, one non-embedding character is provided between the characters to be embedded. This is because when watermark information B is sequentially embedded in consecutive characters, one character interval is shared between adjacent characters, and the distance to one next character can always be controlled. It is to become. For this reason, errors are gradually accumulated, which greatly affects the layout (placement information). However, the present invention is not limited to the described procedure as long as information is embedded using character spacing.

  Finally, in step S207f, it is determined whether or not the character information on the page description data is the last. If it is determined in step S207f that the character information on the page description data is the last, step S207 is terminated. If it is determined that the character information on the page description data is not the last, the process proceeds to step S207a. Return.

  FIG. 6 is a diagram illustrating a change example of the page description data in the present embodiment. First, the electronic document data input to the electronic document data input unit 101 is input. Here, an example of the input electronic document data is page description data 601. Further, in the page description data 601, the portion indicating the distance to the next character, which is a value capable of operating the character spacings P and S, is the portion indicated by the distance data 601a and 601b to the next character. Here, description will be made by paying attention to distances A0 and B0 to the next character arbitrarily selected from the distance data 601a and 601b to the next character.

  Next, the change unit 105 changes the electronic document data based on normalization information for normalizing the character spacing in the document image. Here, an example of the changed electronic document data is page description data 602. In the page description data 602, the portions corresponding to the distance data 601a and 601b to the next character are the distance data 602a and 602b to the next character. The portions corresponding to the distances A0 and B0 to the next character are the distances A1 and B1 to the next character, and the distance to the next character has been changed from A0 to A1 and from B0 to B1. Recognize.

  Next, the embedding unit 107 embeds watermark information B in the electronic document data changed by the changing unit 105. Here, an example of electronic document data after embedding watermark information is page description data 603. In the page description data 602, portions corresponding to distance data 602a and 602b to the next character are 603a and 603b. Further, the portions corresponding to the distances A1 and B1 to the next character are the distances A2 and B2 to the next character, and the distance to the next character has been changed from A1 to A2 and from B1 to B2. Recognize.

  FIG. 7 is a configuration diagram of a watermark information extraction apparatus (information processing apparatus) 700 according to the first embodiment. An embedded document print C is input to the image input unit 701. The detection unit 702 analyzes the positional relationship between characters from the document image input to the image input unit 701. The watermark information extraction unit 703 extracts and outputs the watermark information D embedded in the character positional relationship (character spacing relationship).

  FIG. 8 is a flowchart showing an operation procedure of the watermark information extraction unit 703. First, in step S801, a document image in which watermark information is embedded is input. The document image of the embedded document printed matter C is read from the image input unit 701 such as a scanner.

  In step S802, the detection unit 702 detects a circumscribed rectangle from the document image. In step S803, the detection unit 702 calculates the character spacing from the circumscribed rectangle. The calculation procedure can be performed in the same manner as the process of embedding watermark information. Finally, in step S804, the watermark information extraction unit 703 extracts watermark information. In this extraction process, 1-bit (0 or 1) information is extracted for each set depending on the size relationship between the sets P1 and S1 of the character spacing before and after the rectangle of interest.

  According to this embodiment, after reflecting the character spacing information of the document image in the electronic document data, the watermark information is embedded in the electronic document data. Therefore, it is possible to embed watermark information by manipulating the character spacing for the electronic document data and extract the watermark information from the printed document. In addition, character spacing errors are less likely to occur and the amount of processing is smaller than when embedding on a document image, processing such as block selection or OCR, and converting the processed document image into electronic document data.

  In this embodiment, watermark information is embedded after electronic document data is changed using normalization information. However, the watermark information may be directly embedded without normalization because of the character spacing of the document image.

  In the present embodiment, each process from normalization information calculation to watermark information embedding is performed on the entire document. However, the above-described processes may be performed for each line of the document. As a result, the area for storing the processing results can be reduced.

  In this embodiment, the method of embedding watermark information by adjusting the character spacing has been described. However, the present invention can also be applied to a method of embedding watermark information by adjusting the line spacing. In this case, in the present embodiment, the circumscribed rectangle of the character is the component image to be processed, but the circumscribed rectangle including the character for one line may be the component image to be processed.

  The present invention can be applied not only to adjusting the character spacing and line spacing but also to adjusting the spacing between graphics and characters and the spacing between graphics and graphics. The present invention can be applied not only to embedding information by adjusting the interval, but also to a method of embedding watermark information by changing the size of a figure or character or adjusting the position thereof.

[Modification of First Embodiment]
In the first embodiment described above, the normalization information calculation unit 104 calculates the normalization information by selecting the character spacing pairs P and S in order from the document image. However, as shown in FIG. 17, the character areas (1701a, 1701b) recognized by the page description data (1701) may be different from the character areas (1702a, 1702b) recognized by the document image (1702). As this cause, for example, a case where a part of the figure is erroneously recognized as a character as a result of block selection as in 1702c, and the like can be mentioned. In such a case, normalization is performed using character spacing that does not exist in the page description data. As a result, watermark information cannot be embedded.

  Therefore, normalization information is calculated only for lines having coordinates that match the coordinates of the lines in which character codes exist in the page description data. Therefore, the probability that watermark information can be embedded in each row of page description data is increased.

  FIG. 16 is a flowchart illustrating an operation procedure of the normalized information calculation unit 104 according to the modification of the first embodiment. Note that the processes from step S206j to step S206m are the same as the processes from step S205b to step S205e, respectively, and thus description thereof is omitted.

  First, in step S206g, a line of a document image is selected. For example, selection is made in order from the line near the upper right of the document image.

  In step S206h, it is determined whether or not there is a line in the page description data having a coordinate that coincides with the first coordinate of the line selected in S206g. The coordinates of the beginning of the line in the document image are, for example, the coordinates of the first character of the line such as 1702d in FIG. 17 (horizontal coordinates = “741”, vertical coordinates = “5585”, etc.). On the other hand, the coordinates of the beginning of the line in the page description data are indicated by, for example, the first number (horizontal coordinate = “729”, vertical coordinate = “5584”, etc.) of the line where the character code exists as shown by 1701d in FIG. . Here, the unit of coordinates is pixel for both the document image and the page description data. Note that the coordinates of a portion corresponding to a picture such as 1701c in FIG. This makes it possible to embed watermark information only in the character portion. However, depending on the type of page description data, the coordinates may be assigned only to the character portion. In that case, all the coordinates of the page description data may be determined.

  In determining whether or not the coordinates match, it is considered that some errors occur between the coordinates of the page description data and the coordinates of the document image depending on the document image generation method. Therefore, considering the error, for example, if the coordinate difference is 20 or less, it is determined that the same row. In consideration of the error, it can be determined in FIG. 17 that the horizontal coordinate = “741” and the vertical coordinate = “5585” of the document image 1702 and the horizontal coordinate = “729” and the vertical coordinate = “5584” of the page description data 1701 match. Therefore, it can be seen that the line exists.

  Further, the coordinate data of each line of the page description data is acquired, for example, when the page description data is read in step S201, and is stored in advance in a memory or the like. However, the coordinate data may be searched sequentially in the process of step S206h.

  In step S206h, if there is a line, character spacing sets P and S are selected in order from the beginning of the line in step S206i, and the processes from step S206j to step S206m are performed according to circumstances. In step S206n, it is determined whether or not it is the end of the line, processing is performed until the end of the line, and the process proceeds to step S206o. In step S206o, it is determined whether or not it is the end of the document. If it is not the end of the document, the process proceeds to step S206g, and if it is the end of the document, step S206 is ended. On the other hand, if there is no row in S206h, the process proceeds to step S206o.

<Second Embodiment>
In the first embodiment described above, the changing unit 105 changes the character spacing unconditionally with the normalization information from the document image, regardless of the character in the page description data. Therefore, when punctuation marks are mixed in the page description data, the character spacing before and after the punctuation marks is also changed, which may make the document unnatural.

  FIG. 9 is a diagram showing an example of character spacing sets before and after punctuation marks. In the present embodiment, unlike the first embodiment, the set of character intervals including the character interval immediately after the punctuation mark is not changed, and the watermark information is not embedded in the set of character intervals.

  For example, 901 and 902 correspond to a set of character intervals P and S including a character interval S immediately after the target rectangle 904 and a distance A0 and B0 corresponding to the next character. Watermark information is not embedded in these sets of character intervals. Further, when extracting watermark information, a set of character intervals before and after a circumscribed rectangle not to be embedded is excluded.

  The watermark information embedding device according to the second embodiment has the same configuration as that of the first embodiment described above, but the processing in the changing unit 105 (step S206) and the embedding unit 107 (step S207) is as follows. It is different in point.

[Change unit 105 (step S206)]
FIG. 10 is a flowchart illustrating an operation procedure of the changing unit 105 according to the second embodiment. First, in step S206d, distances A0 and B0 to the next character, which is character information corresponding to the sets P and S of adjacent adjacent character intervals, are selected.

  Next, in step S206e, based on the punctuation mark position information of the page description data A, it is determined whether A0 or B0 is the distance to the next character corresponding to the character spacing immediately after the punctuation mark. The punctuation mark position information is indicated by a character code, for example. If it is not determined in step S206e that A0 or B0 is the distance to the next character corresponding to the character spacing immediately after the punctuation mark, the process proceeds to step S206f. In step S206e, if it is determined that A0 or B0 is the distance to the next character corresponding to the character spacing immediately after the punctuation mark, the process proceeds to step S206g.

  In step S206f, the distances A1 and B1 to the next character after the change are calculated as A1 = A0 + α × X and B1 = B0 + α × Y, and the data content is changed.

  On the other hand, in step S206g, A1 = A0 and B1 = B0. That is, the data content is not changed.

  Finally, in step S206h, it is determined whether or not the character information corresponding to P and S is the last. If it is determined in step S206h that the character information is the last, step S206 ends. If it is determined that the character information is not the last, the process returns to step S206d.

[Embedding unit 107 (step S207)]
FIG. 11 is a flowchart showing an operation procedure of the embedding unit 107 according to the second embodiment. First, in step S207g, distances A1 and B1 to the next character are selected.

  In step S207h, based on the punctuation mark position information of the page description data A, it is determined whether A1 or B1 is the distance to the next character corresponding to the character spacing immediately after the punctuation mark. If it is not determined in step S207h that A1 or B1 is the distance to the next character corresponding to the character interval immediately after the punctuation mark, the process proceeds to step S207i. If it is determined in step S207h that A1 or B1 is the distance to the next character corresponding to the character spacing immediately after the punctuation mark, the process proceeds to step S206m.

  In step S207i, a watermark bit to be embedded is selected. Next, in step S207j, it is determined whether or not the embedded watermark bit is 1. If it is determined that the watermark bit embedded in step S207j is 1, the process proceeds to step S207k. If it is determined that the embedded watermark bit is not 1, the process proceeds to step S207l.

  In step S207k, distances A2 and B2 to the next character after embedding are calculated as A2 = A1 + γ and B2 = B2-γ so that the character spacing corresponding to A1 is larger than the character spacing corresponding to B1. Then, watermark information is embedded. On the other hand, in step S207l, the distances A2 and B2 to the next character after embedding are set to A2 = A1-γ and B2 = B2 + γ so that the character spacing corresponding to A1 is smaller than the character spacing corresponding to B1. And watermark information is embedded.

  On the other hand, in step S207m, A2 = A1 and B2 = B1. That is, watermark information is not embedded.

  Finally, in step S207n, it is determined whether or not the character information on the page description data is the last. If it is determined in step S207n that the character information on the page description data is the last, step S207 is ended. If it is determined that the character information on the page description data is not the last, the process proceeds to step S207g. Return.

  FIG. 12 is a flowchart showing an operation procedure of the watermark information extraction unit 703 according to the second embodiment. The watermark information extraction apparatus 700 is the same as that in the first embodiment, but adds processing related to punctuation marks in the extraction processing.

  First, in step S1201, a document image in which watermark information is embedded is read. Input from an image input unit 701 such as a scanner.

  In step S1202, a circumscribed rectangle is detected from the document image. In step S1203, punctuation marks are detected based on the size of the circumscribed rectangle. The processing in steps S1202 and S1203 is performed by the detection unit 702.

  In step S1204, the detection unit 702 calculates the character spacing excluding the character spacing set including the character spacing immediately after the punctuation mark described above. The calculation method is the same as the processing of the embedding unit 107.

  In step S1205, the watermark information extraction unit 703 extracts watermark information. In this extraction process, 1-bit (0 or 1) information is extracted for each set depending on the size relationship between adjacent sets P1 and S1 of the character spacing before and after.

  In the first and second embodiments described above, watermark information is embedded by adjusting the size relationship between adjacent character spacings. However, when determining whether or not to insert watermark information by comparing each character interval with a threshold value, the present invention is applied only by adding only the character interval information in each corresponding document image. be able to.

<Third Embodiment>
In the present embodiment, the computer executes various processes according to the first embodiment. FIG. 13 is a basic configuration diagram of a computer according to the third embodiment. For example, when all functions are executed in a computer, all the functions of the first embodiment can be realized by a computer by expressing each function configuration by a computer program and causing the computer to read the functions.

  The CPU 1301 controls the entire computer using computer programs and data stored in the RAM 1302 and the ROM 1303. The CPU 1301 performs each process described in the first embodiment and the second embodiment.

  The RAM 1302 includes a storage area for temporarily storing computer programs and data read from the external storage device 1308 and programs and data downloaded from other computer systems 1314 via an I / F (interface) 1315. The RAM 1302 includes a processing area necessary for the CPU 1301 to perform various processes.

  The ROM 1303 stores computer function programs, setting data, and the like. The display control device 1304 performs control processing for displaying an image, characters, and the like on the display 1305. A display 1305 is a display device such as a CRT or a liquid crystal screen, and displays images, characters, and the like.

  The operation input device 1306 is configured by a device that can input various instructions to the CPU 1301 such as a keyboard and a mouse. The I / O 1307 notifies the CPU 1301 of various instructions input via the operation input device 1306.

  The external storage device 1308 functions as a large-capacity information storage device such as a hard disk, and stores an OS (Operating System), a computer program for causing the CPU 1301 to execute the processing according to each of the above embodiments, an input / output document image, and the like. Writing information to the external storage device 1308 and reading information from the external storage device 1308 are performed via the I / O 1309.

  The printer 1310 outputs documents and images. Output data is transmitted from the RAM 1302 or the external storage device 1308 via the I / O 1313. Examples of the printer include an ink jet printer, a laser beam printer, a thermal transfer printer, and a dot impact printer.

  The scanner 1312 reads a document or an image. Input data is transmitted to the RAM 1302 or the external storage device 1308 via the I / O 1313.

  A bus 1316 connects the CPU 1301, ROM 1303, RAM 1302, I / O 1311, I / O 1309, display control device 1304, I / F 1315, I / O 1307, and I / O 1313 to form a network.

  In this embodiment, the computer performs processing excluding the processing by the scanner or printer. However, the scanner or printer uses a dedicated hardware circuit provided in the interior to replace the processing performed by the computer. You may go to

  The first to third embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be interpreted in a limited manner. . That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

<Other embodiments>
Note that this embodiment can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but an apparatus (for example, a copier, a multifunction device, The present invention may be applied to a facsimile machine or the like.

  In the above-described embodiment, a computer-readable recording medium (or storage medium) that records program codes of software that realizes these functions is supplied to the system or apparatus. In this case, it goes without saying that this can also be achieved by the computer (or CPU or MPU) of the system or apparatus reading and executing the program code stored in the recording medium. In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiment, and the recording medium on which the program code is recorded constitutes the present embodiment.

  The present invention is not limited to this, and an operating system (OS) or the like running on a computer performs part or all of the actual processing based on an instruction of the program code. The case where the function is realized is also included.

  Further, the program code read from the recording 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. Thereafter, the CPU of the function expansion card or function expansion unit performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments may be realized by the processing. Needless to say, it is included.

  When this embodiment is applied to the recording medium, the recording medium stores program codes corresponding to the flowcharts and functional configurations described above.

It is a functional block diagram of the watermark information embedding device 100 which concerns on 1st Embodiment and 2nd Embodiment. It is a flowchart which shows the operation | movement procedure of the watermark information embedding apparatus 100 which concerns on 1st Embodiment and 2nd Embodiment. It is a figure which shows the example of the group of a character spacing. It is a flowchart which shows the operation | movement procedure of the normalization information calculation part 104 which concerns on 1st Embodiment. It is a flowchart which shows the operation | movement procedure of the change part 105 which concerns on 1st Embodiment. It is a figure which shows the example of a change of the page description data in 1st Embodiment. It is a functional block diagram of the watermark information extraction apparatus 700 which concerns on 1st Embodiment and 2nd Embodiment. It is a flowchart which shows the operation | movement procedure of the watermark information extraction part 704 which concerns on 1st Embodiment. It is a figure which shows the example of the group of the character space | interval before and behind a punctuation mark. It is a flowchart which shows the operation | movement procedure of the change part 105 which concerns on 2nd Embodiment. It is a flowchart which shows the operation | movement procedure of the embedding part 107 which concerns on 2nd Embodiment. It is a flowchart which shows the operation | movement procedure of the watermark information extraction part 704 which concerns on 2nd Embodiment. It is a basic lineblock diagram of a computer concerning a 3rd embodiment. It is a figure which shows the relationship between the distance of the character of page description data in 1st Embodiment, and the next character. It is a flowchart which shows the operation | movement procedure of the embedding part 107 which concerns on 1st Embodiment. It is a flowchart which shows the operation | movement procedure of the normalization information calculation part 104 which concerns on the modification of 1st Embodiment. It is a figure which shows the coordinate of each line in page description data and a document image.

Claims (11)

An information processing apparatus for embedding information in input electronic document data,
Image generating means for generating a document image from the electronic document data;
Detecting means for detecting layout information of each component image in the generated document image;
Calculation means for calculating normalization information for normalizing the arrangement of each component image based on the detected layout information;
An embedding means for changing the electronic document data based on the calculated normalization information and embedding information in the changed electronic document data;
An information processing apparatus comprising:   The information processing apparatus according to claim 1, wherein the image generation unit generates the document image at a resolution at which the detection unit can detect the layout information. The layout information includes information on the position and size of each component image,
The information processing apparatus according to claim 1, wherein the calculation unit calculates an interval between the component images based on the layout information. Each of the component images is a circumscribed rectangle of each character image,
The information processing apparatus according to claim 3, wherein the detection unit calculates an interval between circumscribed rectangles of the character images based on the layout information.   The calculation means calculates an average value of the character spacing between the noticed rectangle that is the circumscribed rectangle to be noticed and the circumscribed rectangle adjacent to the noticed rectangle based on the character spacing calculated by the detecting means, The information processing apparatus according to claim 4, wherein each character interval calculates normalization information necessary to obtain the average value.   The information processing apparatus according to claim 5, wherein the embedding unit changes information corresponding to at least one of a position or a size of the circumscribed rectangle when changing the electronic document data.   The information processing apparatus according to claim 1, further comprising means for changing the electronic document data so as to correspond to the normalized information calculated on the document image.   8. The information according to claim 1, wherein the embedding unit embeds the information by adjusting a character interval of each character in the electronic document data based on predetermined information. Information processing device. An information processing method for embedding information in input electronic document data,
An image generation step of generating a document image from the electronic document data;
A detection step of detecting layout information of each component image in the generated document image;
A calculation step of calculating normalization information for normalizing each component image based on the detected layout information;
An embedding step for changing the electronic document data based on the calculated normalization information and embedding information in the changed electronic document data;
An information processing method characterized by comprising:   9. A computer program that causes a computer to function as the information processing apparatus according to claim 1 by being read and executed by the computer.   A computer-readable recording medium storing the computer program according to claim 10.

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