JP2005277544A - Watermark evaluation system and method, and watermark evaluation sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a watermark evaluation system capable of performing high precision padding/detection of a watermark for a print document without being affected by print setting of a printer or scanning characteristics of a scanner. <P>SOLUTION: The watermark evaluation system 20 comprises a section 200 for padding a watermark in an evaluation sheet format 251 imparted with marks 252 and 253 for evaluating print density, a section 201 for printing the evaluation sheet format padded with a watermark as an evaluation sheet 250, a scanning section 203 for acquiring the scan image of the evaluation sheet, a section 204 for determining whether print density is suitable for watermark or not based on the print density evaluation mark imparted to the scan image of the evaluation sheet, and a section 202 for altering print density at the print processing section 201 depending on judgment at the density judging section 204. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a digital watermark evaluation system, a digital watermark evaluation method, and a digital watermark evaluation sheet for evaluating embedding / detection of a digital watermark in a printed document.

  2. Description of the Related Art Conventionally, an information embedding method and a detection method in a printed document using digital watermark technology are known (see, for example, Patent Documents 1 and 2). These technologies embed secret information (also referred to as embedded information or confidential information) other than characters and detect the embedded information in a black and white binary printing device that is most widely used as printed matter. The present invention relates to an apparatus and method.

JP 2003-101762 A JP 2003-209676 A

  By the way, in the information embedding method / detection method as described above, the accuracy of detection by the performance of hardware and the setting method such as a printer used when embedding secret information, a scanner used when detecting secret information, and the like. A large impact. When using digital watermark embedding / detection technology in printed documents, various combinations of printers and scanners can be considered. Depending on the printer print settings (toner-saving mode settings, etc.) and scanner characteristics, the digital watermark detection accuracy may be affected. There is also a possibility of effect. From this point of view, there is a demand for a digital watermark technique that can embed / detect a digital watermark with high accuracy in a printed document without being affected by print settings of a printer, scan characteristics of a scanner, and the like.

  The present invention has been made in view of the above problems of the conventional digital watermark technology, and the object of the present invention is to provide an electronic document for a printed document without being affected by the print settings of the printer and the scan characteristics of the scanner. To provide a new and improved digital watermark evaluation system, digital watermark evaluation method, and digital watermark evaluation sheet capable of embedding / detecting watermarks with high accuracy.

  In order to solve the above problems, according to a first aspect of the present invention, there is provided a digital watermark evaluation system for performing evaluation of embedding / detection of a digital watermark in a printed document. The electronic watermark evaluation system of the present invention includes an electronic watermark embedding unit (200) for embedding an electronic watermark in an evaluation sheet format (251) provided with a print density evaluation mark (252, 253), and an electronic watermark embedded therein. A print processing unit (201) that prints the evaluation sheet format as an evaluation sheet (250), a scan processing unit (203) that acquires a scan image of the evaluation sheet, and a print attached to the scan image of the evaluation sheet Based on the density evaluation mark, the density determination unit (204) that determines whether the print density is suitable for digital watermarking, and the print density of the print processing unit (201) according to the determination of the density determination unit (204) And a print density changing unit (202) for changing the above (Claim 1).

  According to such a system, it is possible to print an evaluation sheet provided with a print density evaluation mark and determine whether the print density is suitable for electronic watermarking based on the print density evaluation mark. The print density can be changed according to the evaluation of the print density, and the changed print density can be fed back to the printing process. In this way, high-precision embedding / printing of a digital watermark in a printed document can be performed by automatically evaluating and changing the print density without being affected by the print settings of the print processing unit and the scan characteristics of the scan processing unit. Detection can be performed.

  In the digital watermark evaluation system of the present invention, the following applications are possible.

  The print density changing unit (202) changes the resolution or size of the evaluation sheet format (251) and the digital watermark, and changes the dot size representing the digital watermark, thereby changing the print density of the print processing unit (201). You may make it change (Claim 2). According to such a system, it is possible to set an optimal print density that does not depend on the print density characteristics of the print processing unit when embedding a digital watermark.

  The print density evaluation mark includes a print density evaluation indicator (253) printed so that the density changes stepwise (by dither, error diffusion, etc.), and the density determination unit (204) has a predetermined threshold value. The print density may be evaluated by measuring the area of the binarized print density evaluation indicator (claim 3).

  The print density evaluation mark includes an index mark (logo mark 252) indicating the area of the print density evaluation mark, and the density determination unit (204) determines the area of the print density evaluation mark area by template matching using the index mark. Acquisition may be performed (claim 4).

  Further, the digital watermark signal detection unit (205) for detecting the digital watermark from the scanned image of the evaluation sheet is compared with the digital watermark embedded by the digital watermark embedding unit and the digital watermark detected by the digital watermark signal detection unit. And a digital watermark signal detection accuracy determination unit (206) for determining the signal detection accuracy (claim 5).

  In this case, the print density changing unit (202) changes the print density of the print processing unit (201) according to the determination result of the signal detection accuracy determination unit (206) in addition to the determination of the density determination unit (204). (Claim 6). Simultaneously with the print density evaluation, the digital watermark signal detection accuracy evaluation is performed, and this can be used to change the print density.

  Alternatively, the print density changing unit (202) changes the print density of the print processing unit (201) according to the determination result of the signal detection accuracy determination unit (206) instead of the determination of the density determination unit (204). You may do it. That is, another electronic watermark evaluation system of the present invention includes an electronic watermark embedding unit (200) that embeds an electronic watermark in an evaluation sheet format (251), and an evaluation sheet format in which the electronic watermark is embedded. ) As a print processing unit (201), a scan processing unit (203) for acquiring a scan image of the evaluation sheet, a digital watermark signal detection unit (205) for detecting a digital watermark from the scan image of the evaluation sheet, A digital watermark signal detection accuracy determination unit (206) that compares the digital watermark embedded by the digital watermark embedding unit with the digital watermark detected by the digital watermark signal detection unit to determine the signal detection accuracy; A print density changing unit (2) that changes the print density of the print processing unit (201) according to the determination result of the unit (206). And 2), characterized by comprising (claim 7). In this case, the density determination unit (204) and the print density evaluation marks (252, 253) are not necessary. Then, instead of the print density evaluation, an electronic watermark signal detection accuracy evaluation is performed, and the print density can be changed using this.

  The density determination unit (400) may output the print density and signal detection accuracy of the digital watermark as a quantitative digital watermark evaluation value. The digital watermark printing density and signal detection accuracy, that is, the digital watermark embedding / detection performance can be output as objective values.

  The density determination unit (400) calculates a digital watermark evaluation value by a predetermined function using as parameters the first evaluation value related to the evaluation result of the print density of the digital watermark and the second evaluation value related to the signal detection accuracy of the digital watermark. May be calculated (claim 9). Specifically, for example, according to the degree of deviation from the optimum density for the print density evaluation result, and for the digital watermark detection accuracy evaluation result, 0 (bad) −1 (normal), respectively, according to the accuracy. -2 (good) is classified into three-level evaluation values, and the three-level evaluation results of both are added to classify into five-level evaluation values of 0 (bad) -2 (normal) -4 (good), etc. Thus, the performance evaluation result may be output as an objective and quantitative value.

  Another digital watermark evaluation system according to the present invention is a digital watermark evaluation system (20) for evaluating embedding / detection of a digital watermark in a printed document, and a print density evaluation mark capable of visually evaluating the print density. The digital watermark embedding unit (200) for embedding a digital watermark in the evaluation sheet format (251) to which is attached, and the print processing unit (201) for outputting the evaluation sheet format in which the digital watermark is embedded as an evaluation sheet (250) And a print density change unit (202) that changes the print density of the print processing unit (201) in accordance with the print density designation from the user who visually observes the print density evaluation mark given to the output evaluation sheet. (Claim 10).

  According to such a system, it is possible to visually determine whether or not the print density is optimum for the digital watermark by providing the visually density determination means.

  In this digital watermark evaluation system, the print density evaluation mark (353) includes a print density evaluation indicator (253) printed so that the density changes stepwise (due to dither or error diffusion), A print density evaluation indicator guide (353) added on the print density evaluation indicator, and visually comparing the length of the print density evaluation indicator with the length of the print density evaluation indicator guide. The print density may be evaluated (claim 11).

  In order to solve the above problems, according to a second aspect of the present invention, there is provided a digital watermark evaluation method for evaluating embedding / detection of a digital watermark in a printed document. The electronic watermark evaluation method of the present invention includes an electronic watermark embedding step (S202) in which an electronic watermark is embedded in an evaluation sheet format to which a print density evaluation mark (252, 253) is assigned, and an evaluation sheet in which the electronic watermark is embedded. A print processing step (S203) for printing the format as an evaluation sheet, a scan processing step (S206) for acquiring a scan image of the evaluation sheet, and a print density evaluation mark given to the scan image of the evaluation sheet are also included. In addition, a density determination step (S210) for determining whether the print density is suitable for digital watermarking, a print density change step (S213) for changing the print density in the print processing step in accordance with the determination in the density determination step, (Claim 12).

  According to this method, it is possible to print an evaluation sheet provided with a print density evaluation mark and determine whether the print density is suitable for electronic watermarking based on the print density evaluation mark. The print density can be changed according to the evaluation of the print density, and the changed print density can be fed back to the printing process. In this way, high-precision embedding / printing of a digital watermark in a printed document can be performed by automatically evaluating and changing the print density without being affected by the print settings of the print processing unit and the scan characteristics of the scan processing unit. Detection can be performed.

  The digital watermark evaluation method of the present invention can be applied as follows.

  In the print density change step (S213), the print density in the print processing step is changed by changing the resolution or size of the evaluation sheet format and the digital watermark, and changing the dot size expressing the digital watermark (S102-). S104) (Claim 13). According to such a system, it is possible to set an optimum print density that does not depend on the print density characteristic in the print processing step in embedding a digital watermark.

  The print density evaluation mark includes a print density evaluation indicator (253) printed so that the density changes stepwise (due to dither, error diffusion, etc.), and has a predetermined threshold value in the density determination step (S210). The print density may be evaluated by measuring the area of the binarized print density evaluation indicator (claim 14).

  The print density evaluation mark includes an index mark (logo mark 252) indicating the print density evaluation mark area. In the density determination step (S210), the print density evaluation mark area is determined by template matching using the index mark. Acquisition may be performed (claim 15).

  Further, the digital watermark signal detecting step (S211) for detecting the digital watermark from the scanned image of the evaluation sheet is compared with the digital watermark embedded by the digital watermark embedding unit and the digital watermark detected by the digital watermark signal detecting unit. And a digital watermark signal detection accuracy determination step (S212) for determining the signal detection accuracy.

  In this case, in the print density change step (S213), in addition to the determination in the density determination step (S210), the print density in the print processing step (S203) is changed according to the determination result in the signal detection accuracy determination step (S212). (Claim 17). Simultaneously with the print density evaluation, the digital watermark signal detection accuracy evaluation is performed, and this can be used to change the print density.

  Alternatively, in the print density change step (S213), the print density in the print processing step (S203) is changed according to the determination result in the signal detection accuracy determination step (S212) instead of the determination in the density determination step (S210). You may do it. That is, another electronic watermark evaluation method of the present invention includes an electronic watermark embedding step (S202) for embedding an electronic watermark in an evaluation sheet format, and a printing process for printing the evaluation sheet format in which the electronic watermark is embedded as an evaluation sheet. A step (S203), a scan processing step (S206) for acquiring a scan image of the evaluation sheet, a digital watermark signal detection step (S211) for detecting a digital watermark from the scan image of the evaluation sheet, and a digital watermark embedding step A digital watermark signal detection accuracy determination step (S212) for determining the signal detection accuracy by comparing the embedded digital watermark with the digital watermark detected in the digital watermark signal detection step, and depending on the determination result in the signal detection accuracy determination step Change the print density in the printing process. A step (S213), characterized in that it comprises a (claim 18). In this case, the density determination step (S210) and the print density evaluation marks (252, 253) are unnecessary. Then, instead of the print density evaluation, an electronic watermark signal detection accuracy evaluation is performed, and the print density can be changed using this.

  In the density determination step, the digital watermark printing density and the signal detection accuracy may be output as a quantitative digital watermark evaluation value (S415). The digital watermark printing density and signal detection accuracy, that is, the digital watermark embedding / detection performance can be output as objective values.

  In the density determination step (S415), a digital watermark evaluation value is obtained by a predetermined function using as parameters the first evaluation value relating to the print density evaluation result of the digital watermark and the second evaluation value relating to the signal detection accuracy of the digital watermark. (S413 to S414) may be calculated (claim 20). Specifically, for example, according to the degree of deviation from the optimum density for the print density evaluation result, and for the digital watermark detection accuracy evaluation result, 0 (bad) −1 (normal), respectively, according to the accuracy. -2 (good) is classified into three-level evaluation values, and the three-level evaluation results of both are added to classify into five-level evaluation values of 0 (bad) -2 (normal) -4 (good), etc. Thus, the performance evaluation result may be output as an objective and quantitative value.

  Another electronic watermark evaluation method of the present invention is an electronic watermark evaluation method for evaluating embedding / detection of an electronic watermark in a printed document, and is provided with a print density evaluation mark that allows visual evaluation of the print density. A digital watermark embedding step (S202) for embedding a digital watermark in the evaluation sheet format, a print processing unit (S303) for outputting the evaluation sheet format in which the digital watermark is embedded as an evaluation sheet, and the output evaluation sheet And a print density changing step (S304 to S306) for changing the print density in the print processing step in accordance with the print density designation from the user who visually observes the print density evaluation mark attached to (1). Claim 21).

  According to such a method, it is possible to visually determine whether or not the print density is optimal for the digital watermark by providing the visually density determination means.

  In this digital watermark evaluation system, print density evaluation marks are printed on a print density evaluation indicator printed so that the density changes stepwise (due to dither, error diffusion, etc.) and on the print density evaluation indicator. The print density evaluation indicator guide added to the print density evaluation indicator can be evaluated by visually comparing the length of the print density evaluation indicator with the length of the print density evaluation indicator guide (S304). (Claim 22).

  In order to solve the above problems, according to a third aspect of the present invention, there is provided a digital watermark evaluation sheet (250) for evaluating the embedding / detection of a digital watermark in a printed document. The electronic watermark evaluation sheet of the present invention includes a print density evaluation mark (252, 253) including a print density evaluation indicator (253) printed so that the density changes stepwise (by dither, error diffusion, etc.). (Claim 23).

  According to such a digital watermark evaluation sheet, it is possible to print an evaluation sheet to which a print density evaluation mark is added, and determine whether the print density is suitable for the digital watermark based on the print density evaluation mark. . The print density can be changed according to the evaluation of the print density, and the changed print density can be fed back to the printing process. In this way, high-precision embedding / printing of a digital watermark in a printed document can be performed by automatically evaluating and changing the print density without being affected by the print settings of the print processing unit and the scan characteristics of the scan processing unit. Detection can be performed.

  The electronic watermark evaluation sheet of the present invention can be applied as follows.

  The print density evaluation mark may include an index mark (logo mark 252) indicating the area of the print density evaluation mark. A print density evaluation mark region can be acquired by template matching using an index mark.

  The print density evaluation mark may be capable of visually evaluating the print density (Claim 25). Whether or not the printing density is optimal for the digital watermark can be determined visually without performing a scanning process.

  The print density evaluation mark includes a print density evaluation indicator guide (353) added on the print density evaluation indicator, and visually checks the length of the print density evaluation indicator and the length of the print density evaluation indicator guide. Thus, the print density may be evaluated by comparing them.

  According to another aspect of the present invention, there are provided a program for causing a computer to function as the digital watermark evaluation system, and a computer-readable recording medium on which the program is recorded. Here, the program may be described in any programming language. In addition, as a recording medium, for example, a recording medium that is currently used as a recording medium capable of recording a program, such as a CD-ROM, a DVD-ROM, or a flexible disk, or any recording medium that is used in the future should be adopted. Can do.

  In the above description, the reference numerals in parentheses attached to the constituent elements are merely shown as examples of corresponding constituent elements in the embodiments and drawings described below for easy understanding. It is not limited to.

  As described above, according to the present invention, the accuracy of digital watermarking on a printed document can be improved by automatically evaluating and changing the print density without being affected by the print settings of the printer and the scan characteristics of the scanner. High embedding / detection is possible.

  Exemplary embodiments of a digital watermark evaluation system, a digital watermark evaluation method, and a digital watermark evaluation sheet according to the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
In the first embodiment, the watermark embedding source image and the image embedded as the digital watermark information are not affected by the problem that the digital watermark embedding / detection accuracy may be affected by the print density of the printer, scanner characteristics, or the like. By increasing the resolution and image size, the dot area expressing the digital watermark can be enlarged or reduced, and the print density is changed. Enable watermark embedding / detection.

FIG. 1 is an explanatory diagram showing a configuration of a digital watermark evaluation system according to the present embodiment.
As shown in FIG. 1, the digital watermark evaluation system 10 includes a digital watermark embedding unit 100, a print processing unit 101, and a print image resolution / density changing unit 102. The watermarked print document 150 and the watermark embedding original image 151 are media or data to be processed in the performance evaluation system 10.

  Each component will be described in detail below.

(Digital watermark embedding unit 100)
The digital watermark embedding unit 100 is a functional unit that embeds a digital watermark in a watermark embedding original image (in this embodiment, a black and white binary image) 151 designated by the user. Regarding the method of embedding a digital watermark, it is possible to embed information by giving meaning to a specific dot pattern in a dot pattern such as dither for expressing shading, By embedding watermark information in the spatial frequency domain of the image, it is embedded as invisible information in an image, that is, as a digital watermark in printed matter.

(Print processing unit 101)
The print processing unit 101 is a functional unit that prints an image in which a watermark is embedded in the watermark embedding source image 151 by the digital watermark embedding unit 100 and outputs a watermarked print document 150. In the present embodiment, it is assumed that the print processing unit 101 performs printing by monochrome binary printing.

(Print image resolution / density change unit 102)
When the digital watermark embedding unit 100 embeds a digital watermark in the watermark embedding source image, the print image resolution / density changing unit 102 enlarges the resolution / image size of the watermark embedding source image 151 or the image embedded as the digital watermark. Thus, this is a functional unit that changes the print density by enlarging / reducing the area of a dot representing a digital watermark.

An example of the printing density changing method will be described with reference to FIGS.
As shown in FIGS. 2 and 3, by increasing the resolution and image size of the watermark embedding original image and the digital watermark image, and by making the dot area expressing the digital watermark expandable / reducible for the digital watermark image , The print density can be changed. In FIG. 2, (a) shows an embedding original image with a resolution of 600 dpi. (B) shows the resolution changed from 600 dpi to 1200 dpi. (C) is an image obtained by enlarging the size of the image twice while maintaining the resolution of 1200 dpi. Similarly, in FIG. 3, (a) shows a digital watermark dot pattern with a resolution of 600 dpi. (B) shows the resolution changed from 600 dpi to 1200 dpi. (C) is an image obtained by enlarging the size of the image twice while maintaining the resolution of 1200 dpi.

  When increasing the print density, as shown in FIGS. 2 (d1) and 3 (d1), the dots representing the digital watermark are enlarged and embedded in the watermark embedding source image. When the print density is lowered, the dots are reduced and embedded in the watermark embedding source image as shown in FIGS. 2 (d2) and 3 (d2). In this way, when the generated watermarked image is printed, the watermarked print document is printed out at the printing density of the designated digital watermark.

The present embodiment is configured as described above.
Next, the operation of this embodiment will be described with reference to FIG.

(Step S100)
In step S100, the user designates the digital watermark embedding source image to be embedded with the digital watermark embedding unit 100 of the digital watermark evaluation system, specifies the embedding information, and prints the image in which the watermark is embedded. Specify the print density, and perform the operation to embed and print the digital watermark. In this embodiment, the digital watermark embedding source image is a monochrome binary image.

(Step S101)
In step S101, the digital watermark embedding unit 100 generates a digital watermark image to be embedded as watermark information in the digital watermark embedding source image based on the digital watermark embedding source image and the embedding information designated by the user. Here, the digital watermark embedding source image is not embedded in the digital watermark embedding original image, and each image is separated and stored in the memory of the digital watermark embedding unit 100.

  Regarding the method of embedding digital watermarks in printed materials, it is possible to embed information by giving meaning to dot patterns by dither to express shading, or to embed information in a specific spatial frequency region in an image. For example, an electronic watermark is embedded in a printed material.

  Steps S102 to S104 are processes executed when the user designates the print density so as to increase or decrease the print density. If the print density is not changed, the process proceeds to step S105 without performing the processes of S102 to S104. .

(Step S102)
In step S102, the print image resolution / density changing unit 102 increases the resolution of the digital watermark embedding source image stored in the memory of the digital watermark embedding unit 100 in step S101. In the example of changing the print density shown in FIG. 2, the resolution 600 dpi of the digital watermark embedding original image is doubled to 1200 dpi.

(Step S103)
In step S103, the print image resolution / density changing unit 102 increases the resolution so that the digital watermark embedding source image whose resolution is increased in step S102 is not reduced and printed by increasing the resolution. Enlarge the image size by the specified magnification. In the example of changing the print density shown in FIG. 2, since the resolution has been doubled, the vertical and horizontal sizes of the image size are also doubled, so that printing is performed at the same size as when printing at 600 dpi. be able to.

(Step S104)
In step S104, the print image resolution / density changing unit 102 stores the resolution / image size in the memory of the digital watermark embedding unit 100 in step S101 according to the same procedure as the digital watermark embedding source image whose resolution and image size are increased in steps S102 and S103. Since the resolution and image size of the stored watermark image is increased, and the size of the dots representing the watermark can be finely adjusted, the watermark can be printed according to the watermark setting specified by the user. In order to change the density, the dot size representing the digital watermark in the digital watermark image is enlarged or reduced. Here, when increasing the print density of the digital watermark, the size of the dot representing the digital watermark in the digital watermark image is enlarged, and when reducing the print density, the size of the dot is reduced.

  In the example of changing the print density shown in FIG. 3, what is expressed by 1 dot is expressed by 2 × 2 dots by changing the resolution and image size of the digital watermark image, and is expressed by 2 × 2 dots. Can be changed to 3 × 3 dot or 1 × 1 dot expression to change the density of the digital watermark. When a dot size (small) watermark such as 1 × 1 dot is embedded and printed as shown in the example of changing the print density shown in FIG. When a set print document is output, and a watermark is embedded and printed with a dot size (large) such as 3 × 3 dots, a print document with a dark density setting is output.

(Step S105)
In step S105, the digital watermark embedding unit 100 adds a digital watermark to the digital watermark embedding source image and the digital watermark image stored in the memory of the digital watermark embedding unit 100 by embedding the digital watermark image in the digital watermark embedding source image. An image is generated, and the generated digital watermarked image is printed by the print processing unit 101 to output a watermarked print document.

  For the digital watermark embedding original image and the digital watermark image, when the print density is designated by the user to increase or decrease the print density, the resolution / image size increasing process executed in steps S102 to S104, The process of enlarging / reducing the dot size that represents the digital watermark in the image is performed, but compared with the watermarked printed document that is output by embedding / printing the watermark without performing these processes to change the print density Thus, the same output is output except for the print density of the digital watermark.

(Effects of the first embodiment)
As described above, according to this embodiment, by increasing the resolution and image size of the digital watermark embedding source image and the digital watermark image, it is possible to finely adjust the enlargement / reduction of the dot area expressing the digital watermark. By making it possible to set the print density of the digital watermark at the time of printing, it is possible to change only the watermark print density without affecting the print content of the watermark printed document, and the print density varies depending on the printer model. This makes it possible to change the print density independent of settings, and to embed and detect digital watermarks with stable accuracy.

(Second Embodiment)
In the second embodiment, the printer print density is automatically evaluated and the optimum print density is evaluated for the problem that the digital watermark embedding / detection accuracy may be affected by the print density of the printer, scanner characteristics, and the like. This makes it possible to embed and detect digital watermarks with stable accuracy.

FIG. 5 is an explanatory diagram showing the configuration of the performance evaluation system according to the present embodiment.
As shown in FIG. 5, the performance evaluation system 20 includes an electronic watermark embedding unit 200, a print processing unit 201, a print density changing unit 202, a scan processing unit 203, a scan image optimum density determination unit 204, and an electronic A watermark signal detection unit 205 and a digital watermark signal detection accuracy determination unit 206 are provided. Further, the evaluation sheet 250, the evaluation sheet format 251, the digital watermark embedding signal 254, and the digital watermark detection signal 255 are media, data, or signals to be processed in the performance evaluation system 20. In this embodiment, the watermark embedding source image including the evaluation sheet format 251 and the image to be printed are all monochrome binary images, and the print processing unit 201 is also output by monochrome binary printing. And

  Each component will be described in detail below.

(Digital watermark embedding unit 200)
The digital watermark embedding unit 200 is a functional unit that embeds a digital watermark in a watermark embedding source image such as the evaluation sheet format 251. When the digital watermark is embedded in the evaluation sheet format 251, the embedded digital watermark signal is output and transmitted to the digital watermark signal detection accuracy determination unit 206 as the digital watermark embedded signal 254. Information embedded in the watermark embedding source image such as the evaluation sheet format 251 as watermark information is electronic data such as text data or image data indicating the contents of the embedding source image.

  As for the method of embedding a digital watermark, as in the first embodiment, information embedding is performed by giving meaning to a specific dot pattern in a dot pattern such as dither for expressing shading. By embedding or enabling watermark information to be embedded in a specific spatial frequency region in the image, it is embedded as invisible information in the image, that is, as a digital watermark in the printed matter.

(Print processing unit 201)
The print processing unit 201 is a functional unit that prints a watermarked image such as the evaluation sheet format 251 embedded with a watermark by the digital watermark embedding unit 200 and outputs a watermarked printed document such as the evaluation sheet 250. A watermarked print document such as the evaluation sheet 250 is printed by monochrome binary printing.

(Print density changing unit 202)
The print density changing unit 202 is a functional unit that changes the print density when a watermarked image is printed by the print processing unit 201. As for the print density changing method, the print density setting of the print processing unit 201 is changed to the optimum print density detected by the scan image optimum density determination unit 204. Alternatively, similar to the print image resolution / density changing unit 102 in the first embodiment, the dot area expressing the digital watermark can be enlarged / reduced by increasing the resolution / image size of the evaluation sheet format 251 and the digital watermark image. By enabling fine adjustment and setting the print density of the digital watermark at the time of printing, the print density of the watermark is changed to the optimum print density detected by the scan image optimum density determination unit 204.

(Scan processing unit 203)
The scan processing unit 203 is a functional unit that scans a watermarked print document such as the evaluation sheet 250 printed out by the print processing unit 201 and acquires a scanned image.

(Scanned image optimum density determination unit 204)
The scan image optimum density determination unit 204 is a functional unit that detects an optimum print density from the scan image of the evaluation sheet 250. As for the print density detection method, the print density evaluation indicator 253 included in the scan image of the evaluation sheet 250 is detected by template matching or the like, and the area of the indicator is further measured to print from the indicator area. The optimum print density is detected by judging the density. This print density detection method will be further described later with reference to FIGS. 8A, 8B, and 9. FIG. Here, the optimum area data of the indicator that is the criterion for judgment is stored in advance on the evaluation system side, and the optimum area at the dark print density, the optimum area at the thin print density, etc. By holding the information, the print density can be adjusted with a density setting suitable for embedding a digital watermark.

(Digital watermark detection unit 205)
The digital watermark signal detection unit 205 is a functional unit that extracts a digital watermark detection signal 255 from the scanned image of the evaluation sheet 250 scanned by the scan processing unit 203. The extracted digital watermark detection signal 255 is transmitted to the digital watermark signal detection accuracy determination unit 206. With respect to the detection method of the digital watermark signal, the dither for expressing the light and shade by the method corresponding to the method embedded in the digital watermark embedding unit 200 for the scan image of the evaluation sheet 250 scanned by the scan processing unit 203. Embedded in the evaluation sheet 250 by a method of detecting meaningful information by analyzing a dot pattern by a method, a method of detecting meaningful information by analyzing a specific spatial frequency region in an image, or the like. The digital watermark signal is extracted.

(Digital watermark signal detection accuracy determination unit 206)
The digital watermark embedding signal 254 embedded in the evaluation sheet format 251 by the digital watermark embedding unit 200 is compared with the digital watermark detection signal 255 extracted from the scan image of the evaluation sheet 250 by the digital watermark detection unit 205 to obtain a signal This is a functional unit that determines the signal detection accuracy by measuring the ratio at which the two match, and determines whether a prescribed detection accuracy (for example, a matching rate of 95% or more) is satisfied. The determination result is transmitted to the scan image optimum density determination unit 204. As a result, even if it is determined that the printing density is optimum, those that do not satisfy the detection accuracy are excluded from the set density. Further, when the detection accuracy cannot be satisfied with any print density, it is possible to perform processing such as notifying the user with an error message.

(Evaluation sheet 250)
The evaluation sheet 250 is a print document used for evaluating the influence of the print density of the print processing unit 201 and the scan characteristics of the scan processing unit 203 on the watermark detection accuracy. As shown in FIG. 6, the evaluation sheet 250 prints an image including a detection accuracy evaluation format 251 with embedded watermarks, an electronic watermark logo mark 252, and a print density evaluation indicator 253 from the print processing unit 201. The optimum print density is obtained by performing the print density evaluation and the signal detection accuracy evaluation on the scan image obtained by scanning these with the scan processing unit 203. Note that a plurality of evaluation sheets 250 may be output by the print density setting changing unit 202 with different print density settings.

(Evaluation sheet format 251)
The evaluation sheet format 251 is a format image for creating the evaluation sheet 250. An electronic watermark for signal detection accuracy evaluation is embedded in this image, and an electronic watermark logo mark 252 and a print density evaluation indicator 253 are added and printed, whereby an evaluation sheet 250 is created. Assume that the image from which the evaluation sheet 250 including the evaluation sheet format 251 is printed is a monochrome binary image.

(Digital watermark logo 252)
The electronic watermark logo 252 is an image added to the evaluation sheet format 251 for creating the evaluation sheet 250, and an electronic watermark such as “ABC XXX-Code” shown in FIG. 6 is embedded therein. Can be used as a template for acquiring the print density evaluation indicator 253. At that time, the digital watermark is not embedded in the area of the digital watermark logo mark 252. In addition, the logo mark may not be added unless template matching of the logo mark is performed, for example, by setting the area coordinates of the indicator as a fixed position.

(Print density evaluation indicator 253)
The print density evaluation indicator 253 is an image added to the evaluation sheet format 251 for creating the evaluation sheet 250. As shown in FIG. 6, luminance values from white to black are obtained by dithering or error diffusion. It is an image changed in stages. The print density can be measured based on the scan image of the print density evaluation indicator 253 obtained by scanning the evaluation sheet 250 by the scan processing unit 203, and the optimum print density is detected. When added to the evaluation sheet format 251, it is included in the logo mark design area as a part of the digital watermark logo mark 252 so that the digital watermark is not embedded in the print density evaluation indicator 253. To do. The dither and error diffusion units of the print density evaluation indicator 253 in the evaluation sheet 250 are expressed by a resolution equivalent to the scan resolution in the print density measurement, and do not affect the print density measurement. .

(Digital watermark embedded signal 254)
The digital watermark embedded signal 254 is a digital watermark signal embedded in the evaluation sheet format 251 by the digital watermark embedding unit 200. In the digital watermark signal detection accuracy determination unit 206, the detection accuracy of the digital watermark can be measured by comparing the digital watermark detection signal 255 with the digital watermark detection signal 255 and measuring the ratio at which the signals match.

(Digital watermark detection signal 255)
The digital watermark detection signal 255 is a digital watermark signal extracted from the scanned image of the evaluation sheet format 251 by the digital watermark detection unit 205. In the digital watermark signal detection accuracy determination unit 206, the detection accuracy of the digital watermark can be measured by comparing the digital watermark embedded signal 254 and measuring the ratio of matching signals.

The present embodiment is configured as described above.
Next, the operation of this embodiment will be described with reference to FIG.

(Step S201)
In step S201, processing is started by a user input such as pressing a start button. When the print density setting (watermark detection accuracy priority / watermark print density priority) for the scan image optimum density determination unit 204 by the user is performed, the setting is performed in advance.

(Step S202)
In step S202, the digital watermark embedding unit 200 embeds a digital watermark in the evaluation sheet format 251. At that time, the digital watermark signal embedded in the evaluation sheet format 251 by the digital watermark embedding unit 200 is transmitted to the digital watermark signal detection accuracy determination unit 206 as the digital watermark embedded signal 254. When changing the print density of the digital watermark by the print density changing unit 202 using the same means as in steps S102 to S105 of the first embodiment, the digital watermark image is not embedded in the digital watermark embedding source image, and the respective images are separated. In this state, by increasing the resolution and image size of the digital watermark embedding source image and the digital watermark image, it is possible to finely adjust the dot area to express the digital watermark, and to enlarge or reduce the dot area. After changing the print density of the digital watermark at the time of printing, the digital watermark image is embedded in the digital watermark embedding source image.

(Step S203)
In step S <b> 203, the print processing unit 201 prints the evaluation sheet format 251 and outputs the evaluation sheet 250. When printing the evaluation sheet format 251, the digital watermark logo mark 252 such as “ABC XXX-Code” shown in FIG. 6 and the luminance value from white to black are changed stepwise by dithering, error diffusion, or the like. An image print density evaluation indicator 253 is added to the image in the evaluation format 251 and then printed by the print processing unit 201.

  Further, by printing a plurality of evaluation sheets 250 from the print processing unit 201 with different print density settings by the print density changing unit 202, it is possible to compare the respective evaluation results and improve accuracy. In this case, in steps S <b> 204 to S <b> 212 described below, when there are a plurality of evaluation sheets 250 printed out by the print processing unit 201, all the evaluation sheets 250 are repeatedly processed.

(Step S204)
In step S <b> 204, the user sets the evaluation sheet 250 printed out by the print processing unit 201 in the scan processing unit 203.

(Step S205)
In step S <b> 205, after setting the evaluation sheet 250 in the scan processing unit 203, the user inputs such as pressing a scan start button to start the scan processing by the scan processing unit 203.

(Step S206)
In step S <b> 206, the scan processing unit 203 scans the evaluation sheet 250 and acquires a scan image of the evaluation sheet 250. FIG. 8A and FIG. 8B show details of the processing in steps S206 to S210. In FIG. 8A and FIG. 8B, it is assumed that scanning is performed with an 8-bit gray scale (8-bit Gray) as an example.

(Step S207)
In step S207, the scan image of the evaluation sheet 250 shown in FIG. 8A (a) is binarized. Here, as an example, it is assumed that binarization is performed with a threshold value of 128 for an image scanned in 8-bit gray scale. FIG. 8A (b) shows a scanned image of the binarized evaluation sheet 250. By the binarization process, the indicator is converted into a black rectangle.

(Step S208)
In step S208, as shown in FIG. 8A (c), a digital watermark logo mark 252 such as “ABC XXX-Code” is detected from the scanned image of the binarized evaluation sheet 250 by template matching or the like. .

(Step S209)
FIG. 8B is an explanatory diagram showing a post-process of FIG. 8A. In step S209, as shown in FIG. 8B (a), labeling processing or the like is performed from the print density evaluation indicator 253 included in the detected digital watermark logo mark 252, and binarized and converted into a black rectangle. Measure the area of the indicator. Here, a case where the digital watermark logo mark 252 is used as an example of obtaining the area coordinates of the print density evaluation indicator 253 will be described. However, when the area coordinates of the indicator are fixed positions, the logo mark template matching is performed. There is no need to do so, so the logo mark is not essential.

(Step S210)
In step S210, the scan image optimum density determination unit 204 compares the measured area of the print density evaluation indicator 253 with the preset area for optimum print density scan to detect the optimum print density, Information on the optimum print density is transmitted to the print density changing unit 202. Here, as shown in FIG. 8B (b1), if the area of the print density evaluation indicator 253 is smaller than the preset optimum print density scan area, it is determined that the print density is low, and the print density is increased. Control as follows. As shown in FIG. 8B (b2), when the area of the print density evaluation indicator 253 is substantially the same as the preset optimum print density scan area, it is determined that the print density is optimum, and the print density remains as it is. Control to keep. As shown in FIG. 8B (b3), when the area of the print density evaluation indicator 253 is larger than the preset optimum print density scan area, it is determined that the print density is high, and control is performed to lower the print density. . In this way, the optimum print density is detected.

  Here, the optimum area data of the indicator that is the criterion for judgment is stored in advance on the evaluation system side, and the optimum area at the dark print density, the optimum area at the thin print density, etc. By holding the information, the print density can be adjusted with a density setting suitable for embedding a digital watermark. This makes it possible to specify the print density to be specified by the user, such as determining that the print density setting can be made as low as possible in order to reduce the amount of toner used, or determining that the print density setting can be set to a dark print density when the paper has a background pattern. It is also possible to make a corresponding print density determination.

  The print density determination according to the user print density designation will be described with reference to FIG. In the example shown in FIG. 9, first, as shown in FIG. 9A, labeling processing or the like is performed from the print density evaluation indicator 253 included in the detected digital watermark logo mark 252, and binarized and blackened. The area of the indicator converted into the rectangle is measured. Then, as shown in FIG. 9B, the scan image optimum density determination unit 204 compares the measured area of the print density evaluation indicator 253 with the preset area for the optimum print density scan. , Detect the optimal print density. At this time, in the case of a user setting of a dark print density, as shown in FIG. 9 (c1), the specified area is enlarged. Further, for example, in the case of user setting for accuracy priority designation, as shown in FIG. 9 (c2), it is set to a predetermined prescribed area similar to the case of FIG. 8B. In addition, in the case of a user setting with a low print density, as shown in FIG. 9C3, the specified area is reduced.

(Step S211)
In step S <b> 211, the digital watermark detection unit 205 detects the digital watermark detection signal 255 from the scanned image in the evaluation sheet format 251 and transmits it to the digital watermark signal detection accuracy determination unit 206.

(Step S212)
In step S212, the digital watermark signal detection accuracy determination unit 206 uses the digital watermark embedding signal 254 embedded in the evaluation sheet format 251 by the digital watermark embedding unit 200, and the scan image of the evaluation sheet format 251 by the digital watermark detection unit 205. The digital watermark detection signal 255 detected from the above is compared, the signal detection accuracy is obtained by measuring the ratio at which the signals match, and it is determined whether or not the specified detection accuracy is satisfied (for example, the matching rate is 95% or more). , The determination result is transmitted to the scan image optimum density determination unit 204. This is because, in the print density setting by the print density evaluation indicator 253, there may be a case where the specified digital watermark signal detection accuracy cannot be satisfied. Even when the optimum print density is determined, the detection accuracy is satisfied. Otherwise, it is excluded from the set concentration. Further, when the detection accuracy cannot be satisfied at any printing density, a process such as notifying the user with an error message can be performed.

(Step S213)
In step S213, the print density changing unit 202 changes the setting to the optimum print density based on the optimum print density information obtained in step S210 and the digital watermark signal detection accuracy determination result obtained in step S212. . When the evaluation is performed by printing a plurality of evaluation sheets 250 having different densities, the average value, the mode value, the median value, etc. of each result are measured and changed as the optimum print density setting. If the specified signal detection accuracy cannot be satisfied even at the optimum print density, change to a print density that satisfies the signal detection accuracy. If any of the print densities does not satisfy the specified signal detection accuracy , An error message indicating that the accuracy could not be satisfied is notified to the user.

  Regarding the print density setting changing method by the print density changing unit 202, one is a method for changing the print density by changing the print density setting on the apparatus side of the print processing unit 201, and the other is a first method. Similar to the print image resolution / density changing unit 102 in the first embodiment, by increasing the resolution / image size of the evaluation sheet format 251 and the digital watermark image, fine adjustment of enlargement / reduction of the dot area expressing the digital watermark is performed. There is a method of changing the print density to an optimum print density by making it possible to set the print density of the electronic watermark at the time of printing.

(Effect of 2nd Embodiment)
As described above, according to the present embodiment, an optimum print density setting is performed by printing and scanning an evaluation sheet for objective evaluation, and performing print density evaluation and digital watermark signal detection accuracy evaluation. By detecting and setting, the user can set the optimum print density for the digital watermark only by printing and scanning the evaluation sheet. Also, when evaluating with various combinations of printers and scanners, it is possible to easily set the optimum print density for the digital watermark by the same method.

(Third embodiment)
In the third embodiment, in order to solve the problem that the digital watermark embedding / detection accuracy may be affected by the print density and scanner characteristics of the printer, the setting of the print density of the printer is objectively appropriate. By making it possible to easily determine whether or not the value is visually, the user can easily embed and detect a digital watermark with stable accuracy without using a scanner.

FIG. 10 is an explanatory diagram showing the configuration of the performance evaluation system according to the present embodiment.
The performance evaluation system 30 includes a digital watermark embedding unit 200, a print processing unit 201, and a print density changing unit 202, as shown in FIG. The evaluation sheet 350 and the evaluation sheet format 251 are media or data to be processed in the performance evaluation system 30.

  Each component will be described in detail below. It should be noted that redundant description of components that are substantially the same as those of the second embodiment is omitted.

(Evaluation sheet 350)
As shown in FIG. 11, the evaluation sheet 350 includes an electronic watermark logo mark 252, a print density evaluation indicator 253, and a print density evaluation indicator guide 353, in addition to the evaluation sheet format 251 of the second embodiment. , The print density evaluation indicator line 354 is added and printed.

(Indicator Guide 353 for Print Density Evaluation)
The print density evaluation indicator guide 353 is an image showing the length of the print density evaluation indicator 253 when the print density setting is appropriate. The user can visually check whether the print density setting of the print processing unit 201 is appropriate. It can be confirmed objectively. Unlike the guides in the explanatory diagrams of the second and fourth embodiments, the print density evaluation indicator guide 353 is a user-visible guide that is actually printed on the evaluation sheet 350.

  The print density evaluation indicator guide 353 is added on the print density evaluation indicator 253 as shown in FIG. Then, as shown in FIG. 12A, the print density indicator guide 352 and the print density indicator line 353 are printed, and the print density is confirmed visually. As shown in FIG. 12B1, when the print density evaluation indicator 253 looks longer than the print density evaluation indicator guide 353, it is determined that the print density is high. Further, as shown in FIG. 12B2, if the print density evaluation indicator 253 looks almost the same length as the print density evaluation indicator guide 353, it is determined that the print density is appropriate. Also, as shown in FIG. 12B3, when the print density evaluation indicator 253 appears shorter than the print density evaluation indicator guide 353, it is determined that the print density is low.

(Print density evaluation indicator line 354)
The print density evaluation indicator line 354 is an image for improving the visibility of the length of the print density evaluation indicator 253 when the user visually confirms the length of the print density evaluation indicator 253.

  As shown in FIGS. 11 and 12, the visibility of the print density evaluation indicator 253 is improved by making the range added to the print density evaluation indicator 253 and the print density evaluation indicator line 354 visible. The print density is determined by comparing with the print density evaluation indicator guide 353. That is, if the print density evaluation indicator line 354 can be visually confirmed and the print density evaluation indicator guide 353 is close, it is understood that the print density setting is appropriate. The indicator line is an example for making it easier to see the indicator for visual determination, and other methods for making the indicator easier to see are also conceivable.

The present embodiment is configured as described above.
Next, the operation of this embodiment will be described with reference to FIG.
Note that redundant description of operations substantially similar to those of the second embodiment is omitted.

(Step S303)
In step S303, as in step S203 in the second embodiment, the print processing unit 201 prints the evaluation sheet format 251 and outputs the evaluation sheet 250. When printing the evaluation sheet format 251, an image of the evaluation format 251 is added to the print density evaluation indicator guide 353 and the print density evaluation indicator line 354 in addition to the digital watermark logo mark 252 and the print density evaluation indicator 253. Then, printing is performed by the print processing unit 201.

  Also, by printing a plurality of evaluation sheets 250 from the print processing unit 201 with different print density settings by the print density changing unit 202, it is possible to simultaneously evaluate a plurality of print density conditions and improve accuracy. As for the print density setting method, fine adjustment of enlargement / reduction of the dot area expressing the digital watermark is performed by increasing the resolution / image size in the first embodiment together with the print density setting on the print processing unit 201 side. It is also possible to use a method of changing the print density of the digital watermark at the time of printing by enlarging / reducing the dot area.

(Step S304)
In step S304, the user visually confirms the print density evaluation indicator 253 that has been printed out, and displays the length of the print density evaluation indicator line 354 and the print density evaluation indicator guide 353 included in the print density evaluation indicator 253. Compare. As for the print density confirmation method, as shown in FIG. 12, the user determines that the print density is too dark when the print density evaluation indicator line 354 can be seen outside the range of the print density evaluation indicator guide 353. Conversely, when the print density evaluation indicator line 354 is not visible in the print density evaluation indicator guide 353, it is determined that the print density is too low.

(Step S305)
In step S305, the user visually confirms the print density evaluation indicator 253 printed out, and as a result, it is determined that the print density evaluation indicator line 354 is longer than the print density evaluation indicator guide 353, that is, the print density is high. In this case, the user changes the watermark print density setting to a light print density.

(Step S306)
In step S306, when the user visually confirms the print density evaluation indicator 253 printed out, the print density evaluation indicator line 354 is shorter than the print density evaluation indicator guide 353, that is, the print density is low. The user changes the watermark print density setting to a dark print density.

(Effect of the third embodiment)
As described above, according to the present embodiment, by comparing the length of the indicator guide and the indicator or indicator line for print density evaluation that is included in the evaluation sheet and can be visually confirmed by the user. The user can easily determine visually whether the print density is appropriate for the electronic watermark and only by the output from the printer.

(Fourth embodiment)
In the fourth embodiment, in response to the problem that the digital watermark embedding / detection accuracy may be affected by the printing density of the printer, scanner characteristics, etc., the digital watermark printing / detection performance is objectively evaluated by the evaluation system. By indicating the numerical value as a numerical value, it is possible to easily confirm that the electronic watermark can be embedded and detected with stable accuracy even when the setting is performed by the user, such as the setting of the print density of the printer.

FIG. 14 is an explanatory diagram showing the configuration of the performance evaluation system according to the present embodiment.
As shown in FIG. 14, the performance evaluation system 40 includes an electronic watermark embedding unit 200, a print processing unit 201, a print density changing unit 202, a scan processing unit 203, a scan image optimum density determination unit 204, and an electronic A watermark signal detection unit 205, a digital watermark signal detection accuracy determination unit 206, and a digital watermark embedding / detection performance value output unit 400 are provided. The evaluation sheet 250, the evaluation sheet format 251, the digital watermark embedding signal 254, the digital watermark detection signal 255, and the digital watermark embedding / detection performance value 450 are the medium, data, or Signal.

  Each component will be described in detail below. It should be noted that redundant description of components that are substantially the same as those of the second embodiment is omitted.

(Digital watermark embedding / detection performance value output unit 400)
The digital watermark embedding / detection performance value output unit 400 is a functional unit that calculates and outputs a digital watermark embedding / detection performance value 450 from the results of the scan image optimum density determination unit 204 and the digital watermark signal detection accuracy determination unit 206. .

  An example of a method for calculating the digital watermark embedding / detection performance value 450 is shown in FIG. As an example here, the results of the scanned image optimum density determination unit 204 and the signal detection accuracy determination unit 206 are classified into three stages of good (2) -normal (1) -bad (0), respectively, and the results of both are classified. The objective performance value is calculated, for example, by calculating the five-level evaluation values from good (4) to normal (2) to bad (0).

(Digital watermark embedding / detection performance value 450)
The digital watermark embedding / detection performance value 450 is obtained by quantifying the performance of digital watermark embedding / detection accuracy from the results of the scan image optimum density determination unit 204 and the digital watermark signal detection accuracy determination unit 206.

The present embodiment is configured as described above.
Next, the operation of this embodiment will be described with reference to FIG.
Note that redundant description of operations substantially similar to those of the second embodiment is omitted.

(Step S413)
In step S413, the digital watermark embedding / detection performance value output unit 400 compares the area of the print density evaluation indicator 253 with the area in the case of the optimum print density, and determines whether the print density is appropriate. The judgment is calculated as an objective numerical value. As for the calculation method of the evaluation value of the print density, as shown in FIG. 15A, it is good (2) -normal (1) -bad depending on the degree of deviation of the area from the optimum print density. A method of classifying into three stages (0) is conceivable. For example, if it almost coincides with the specified area, it is judged as good (2). If the deviation from the specified area is within the allowable range, it is judged as normal (1). If the deviation from the specified area exceeds the allowable range, it is judged as bad (0).

(Step S414)
In step S414, the digital watermark embedding / detection performance value output unit 400 compares the digital watermark embedding signal 254 and the digital watermark detection signal 255 to measure the detection accuracy, and objectively determines whether the detection accuracy is appropriate. Calculated as a simple numerical value. As for the calculation method of the evaluation value of detection accuracy, as shown in FIG. 15 (b), it is good (2) -normal (1) -bad (0) according to the degree of deviation from the optimal detection accuracy. A method such as classification into three stages is conceivable. For example, if the signal detection accuracy of the digital watermark is a result equal to or higher than the reference value, it is determined as good (2). If the digital watermark signal detection accuracy is below the reference value and within the allowable range, it is determined as normal (1). If the digital watermark signal detection accuracy is below the reference value and out of the allowable range, it is determined as bad (0).

(Step S415)
In step S415, the digital watermark embedding / detection performance value output unit 400 combines the evaluation value of the print density calculated in step S413 and the evaluation value of the detection accuracy calculated in step S414, thereby embedding / detecting the digital watermark. A performance value 450 is calculated. As shown in FIG. 15, the print density evaluation value calculation method includes the print density evaluation value (0) to (2), which is a three-stage evaluation value, and the detection accuracy evaluation value (0). It is conceivable to add the three-level evaluation values of (2) to total the results of the two and calculate with a five-level evaluation value of good (4) to normal (2) to bad (0). .

(Effect of the fourth embodiment)
As described above, according to this embodiment, the digital watermark printing density and detection accuracy are output as numerical values by the evaluation system, so that the user can easily know the digital watermark embedding / detection performance. It is also possible to easily confirm whether the print density setting of the printer set by the user can embed / detect the electronic watermark with stable accuracy.

  The preferred embodiments of the digital watermark evaluation system, the digital watermark evaluation method, and the digital watermark evaluation sheet according to the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be obvious to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, the following modifications and usage forms are possible.

(1) By using a logo mark, it is possible to perform evaluation not only as an electronic watermark evaluation system for printed matter but also incorporated in a part of an ordinary electronic watermark embedding / detection system. In this case, the evaluation sheet format that becomes the original image of the evaluation sheet is not limited, and the evaluation can be performed based on the image used in the actual processing.

(2) By integrating the print processing unit and the scan processing unit, it is possible to automate the printing to scan processing in the evaluation. In this case, since all the processes can be automated, it is possible to automatically calibrate to the optimum print density when the power is turned on.

(3) Regarding the print density evaluation, in addition to the print density evaluation method using the evaluation indicator, it is possible to print characters with different print densities by dithering or error diffusion to determine whether scanning or visual confirmation is possible. A method is also conceivable.

(4) In the digital watermark embedding / detection performance value output, it is possible to display a message such as “Please raise the print density setting” according to the print density evaluation result. Regarding the output format of performance values, not only numerical values but also methods of expression using characters, images, etc. can be considered.

(5) In the output of the digital watermark embedding / detection performance value, according to the setting by the user or the like, the evaluation value is weighted by giving priority to the print density evaluation result value and the digital watermark signal detection accuracy evaluation result value. It can also be output.

(6) A setting for manually or automatically changing the print density is provided, and in the case of manual, the print density can be changed by a user's own operation by a message such as “Please raise the print density setting”.

(7) With regard to the evaluation sheet, any size, thickness, material, etc. can be used as long as it is a medium that can be processed by the print processing unit and scan processing unit.

(8) The watermark embedding process does not necessarily have to be performed for each evaluation. A watermarked image and a digital watermark embedding signal may be prepared in advance, and the print processing unit may print the watermarked image.

(9) The evaluation start method does not necessarily require input from the user. When the power is turned on, an evaluation sheet is automatically output. When the evaluation sheet is set in the scanner, scanning is automatically started. Evaluation can also be performed.

(10) By increasing the image resolution and image size, the dot density can be enlarged / reduced and the print density is changed to refine the density gradation of the indicator by dithering and error diffusion. , It is possible to improve the accuracy of print density evaluation.

  The present invention is applicable to a digital watermark evaluation system, a digital watermark evaluation method, and a digital watermark evaluation sheet for evaluating the embedding / detection of a digital watermark in a printed document.

It is explanatory drawing which shows the structure of 1st Embodiment. It is explanatory drawing which shows the example of printing density change. It is explanatory drawing which shows the example of printing density change. It is explanatory drawing which shows operation | movement of 1st Embodiment. It is explanatory drawing which shows the structure of 2nd Embodiment. It is explanatory drawing which shows the sheet | seat for evaluation. It is explanatory drawing which shows operation | movement of 2nd Embodiment. It is explanatory drawing which shows the detection method of optimal printing density. It is explanatory drawing which shows the detection method of optimal printing density. It is explanatory drawing which shows the case where there is user designation | designated of watermark printing density. It is explanatory drawing which shows the structure of 3rd Embodiment. It is explanatory drawing which shows the sheet | seat for evaluation. It is explanatory drawing which shows the printing density confirmation method by visual observation. It is explanatory drawing which shows operation | movement of 3rd Embodiment. It is explanatory drawing which shows the structure of 4th Embodiment. It is explanatory drawing which shows the calculation method of a digital watermark embedding and detection performance value. It is explanatory drawing which shows operation | movement of 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Digital watermark evaluation system 100 Digital watermark embedding part 101 Print processing part 102 Print image resolution and density change part 20 Performance evaluation system 200 Digital watermark embedding part 201 Print process part 202 Print density change part 203 Scan process part 204 Scan image optimum density judgment Unit 205 digital watermark signal detection unit 206 digital watermark signal detection accuracy determination unit 250 evaluation sheet 251 evaluation sheet format 252 digital watermark logo mark 253 print density evaluation indicator 254 digital watermark embedded signal 255 digital watermark detection signal 30 performance evaluation system 352 Evaluation sheet 353 Print density evaluation indicator guide 354 Print density evaluation indicator line 40 Performance evaluation system 400 Digital watermark embedding / detection performance value output unit 450 Digital watermark embedding / detection performance value

Claims (26)

A digital watermark evaluation system for evaluating embedding / detection of a digital watermark in a printed document,
An electronic watermark embedding unit for embedding an electronic watermark in an evaluation sheet format to which a mark for evaluating print density is attached;
A print processing unit for printing the evaluation sheet format in which the electronic watermark is embedded as an evaluation sheet;
A scan processing unit for obtaining a scanned image of the evaluation sheet;
A density determination unit that determines whether the print density is suitable for the digital watermark based on the print density evaluation mark given to the scanned image of the evaluation sheet;
A print density changing unit that changes the print density of the print processing unit in accordance with the determination of the density determining unit;
An electronic watermark evaluation system characterized by comprising. The print density changing unit is
2. The print density of the print processing unit is changed by changing the resolution or size of the evaluation sheet format and the digital watermark, and changing the dot size expressing the digital watermark. The electronic watermark evaluation system described in 1. The print density evaluation mark includes a print density evaluation indicator printed so that the density changes stepwise.
The digital watermark evaluation system according to claim 1, wherein the density determination unit evaluates the print density by measuring an area of the print density evaluation indicator binarized with a predetermined threshold. The print density evaluation mark includes an index mark indicating an area of the print density evaluation mark,
The electronic watermark evaluation system according to claim 1, wherein the density determination unit acquires the area of the print density evaluation mark by template matching using the index mark. further,
A digital watermark signal detection unit for detecting a digital watermark from the scanned image of the evaluation sheet;
A digital watermark signal detection accuracy determination unit that determines a signal detection accuracy by comparing the digital watermark embedded by the digital watermark embedding unit and the digital watermark detected by the digital watermark signal detection unit;
The digital watermark evaluation system according to claim 1, further comprising:   The print density changing unit changes the print density of the print processing unit according to a determination result of the signal detection accuracy determination unit in addition to the determination of the density determination unit. Digital watermark evaluation system. A digital watermark evaluation system for evaluating embedding / detection of a digital watermark in a printed document,
An electronic watermark embedding unit for embedding an electronic watermark in an evaluation sheet format;
A print processing unit for printing the evaluation sheet format in which the electronic watermark is embedded as an evaluation sheet;
A scan processing unit for obtaining a scanned image of the evaluation sheet;
A digital watermark signal detection unit for detecting a digital watermark from the scanned image of the evaluation sheet;
A digital watermark signal detection accuracy determination unit that determines a signal detection accuracy by comparing the digital watermark embedded by the digital watermark embedding unit and the digital watermark detected by the digital watermark signal detection unit;
A print density changing unit that changes a print density of the print processing unit according to a determination result of the signal detection accuracy determination unit;
An electronic watermark evaluation system characterized by comprising.   The digital watermark evaluation system according to claim 1, wherein the density determination unit outputs a print density and signal detection accuracy of the digital watermark as a quantitative digital watermark evaluation value. The concentration determination unit
Calculating the digital watermark evaluation value by a predetermined function using as parameters the first evaluation value relating to the print density evaluation result of the digital watermark and the second evaluation value relating to the signal detection accuracy of the digital watermark. 9. The digital watermark evaluation system according to claim 8, wherein A digital watermark evaluation system for evaluating embedding / detection of a digital watermark in a printed document,
A digital watermark embedding unit that embeds a digital watermark in an evaluation sheet format provided with a print density evaluation mark capable of visually evaluating the print density;
A print processing unit for outputting the evaluation sheet format in which the electronic watermark is embedded as an evaluation sheet;
A print density changing unit that changes the print density of the print processing unit in accordance with a print density designation from a user who visually observes the print density evaluation mark given to the output evaluation sheet;
An electronic watermark evaluation system characterized by comprising: The print density evaluation mark is
A print density evaluation indicator printed so that the density changes stepwise;
An indicator guide for print density evaluation added on the indicator for print density evaluation;
Including
11. The digital watermark evaluation system according to claim 10, wherein the print density can be evaluated by visually comparing a length of the print density evaluation indicator with a length of the print density evaluation indicator guide. An electronic watermark evaluation method for evaluating embedding / detection of an electronic watermark in a printed document,
An electronic watermark embedding step of embedding an electronic watermark in an evaluation sheet format to which a print density evaluation mark is attached;
A printing process for printing the evaluation sheet format in which the electronic watermark is embedded as an evaluation sheet;
A scan processing step of acquiring a scan image of the evaluation sheet;
A density determination step for determining whether the print density is suitable for the digital watermark based on the print density evaluation mark given to the scan image of the evaluation sheet;
In response to the determination in the density determination step, a print density change step for changing the print density in the print processing step;
An electronic watermark evaluation method comprising: In the printing density changing step,
The print density in the print processing unit step is changed by changing a resolution or size of the evaluation sheet format and the digital watermark, and changing a dot size expressing the digital watermark. 12. The electronic watermark evaluation method according to 12. The print density evaluation mark includes a print density evaluation indicator printed so that the density changes stepwise.
14. The digital watermark evaluation method according to claim 12, wherein in the density determination step, the print density is evaluated by measuring an area of the print density evaluation indicator binarized with a predetermined threshold value. The print density evaluation mark includes an index mark indicating an area of the print density evaluation mark,
15. The digital watermark evaluation method according to claim 12, wherein, in the density determination step, the print density evaluation mark area is acquired by template matching using the index mark. further,
A digital watermark signal detecting step of detecting a digital watermark from the scanned image of the evaluation sheet;
A digital watermark signal detection accuracy determination step of determining a signal detection accuracy by comparing the digital watermark embedded by the digital watermark embedding unit and the digital watermark detected by the digital watermark signal detection unit;
16. The digital watermark evaluation method according to claim 12, further comprising:   17. The print density change step according to claim 16, wherein the print density in the print processing step is changed according to the determination result in the signal detection accuracy determination step in addition to the determination in the density determination step. Digital watermark evaluation method. An electronic watermark evaluation method for evaluating embedding / detection of an electronic watermark in a printed document,
A digital watermark embedding process for embedding a digital watermark in the evaluation sheet format;
A printing process for printing the evaluation sheet format in which the electronic watermark is embedded as an evaluation sheet;
A scan processing step of acquiring a scan image of the evaluation sheet;
A digital watermark signal detecting step of detecting a digital watermark from the scanned image of the evaluation sheet;
A digital watermark signal detection accuracy determination step for determining a signal detection accuracy by comparing the digital watermark embedded in the digital watermark embedding step with the digital watermark detected in the digital watermark signal detection step;
According to the determination result in the signal detection accuracy determination step, a print density change step for changing the print density in the print processing step;
An electronic watermark evaluation method comprising:   19. The digital watermark evaluation method according to claim 12, wherein in the density determination step, the print density and signal detection accuracy of the digital watermark are output as a quantitative digital watermark evaluation value. In the concentration determination step,
Calculating the digital watermark evaluation value by a predetermined function using as parameters the first evaluation value relating to the print density evaluation result of the digital watermark and the second evaluation value relating to the signal detection accuracy of the digital watermark. The digital watermark evaluation method according to claim 19, wherein An electronic watermark evaluation method for evaluating embedding / detection of an electronic watermark in a printed document,
A digital watermark embedding step of embedding a digital watermark in an evaluation sheet format provided with a print density evaluation mark capable of visually evaluating the print density;
A print processing unit for outputting the evaluation sheet format in which the electronic watermark is embedded as an evaluation sheet;
A print density changing step for changing the print density in the print processing step according to a print density designation from a user who visually observes the print density evaluation mark given to the output evaluation sheet;
An electronic watermark evaluation method comprising: The print density evaluation mark is
A print density evaluation indicator printed so that the density changes stepwise;
An indicator guide for print density evaluation added on the indicator for print density evaluation;
Including
The digital watermark evaluation method according to claim 21, wherein the print density can be evaluated by visually comparing a length of the print density evaluation indicator with a length of the print density evaluation indicator guide. An electronic watermark evaluation sheet for evaluating embedding / detection of an electronic watermark in a printed document,
An electronic watermark evaluation sheet provided with a print density evaluation mark including a print density evaluation indicator printed so that the density changes stepwise.   The digital watermark evaluation sheet according to claim 23, wherein the print density evaluation mark includes an index mark indicating a region of the print density evaluation mark.   25. The electronic watermark evaluation sheet according to claim 23, wherein the print density evaluation mark can be visually evaluated for print density. The print density evaluation mark includes a print density evaluation indicator guide added on the print density evaluation indicator,
26. The digital watermark evaluation sheet according to claim 25, wherein the print density can be evaluated by visually comparing the length of the print density evaluation indicator with the length of the print density evaluation indicator guide.

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