JP2001309155A - Image processing apparatus, method, and computer-readable storage medium - Google Patents

Abstract

(57) [Problem] To protect a digital image or a printed image according to various uses by using an add-on method and a digital watermarking method in combination. A digital watermark embedding unit (11) embeds an invisible digital watermark in an input image (10). Next, when printing the image in which the digital watermark is embedded, an output image 13 is obtained by adding a specific dot pattern of yellow by the add-on adding unit 12. At this time, by dividing the image into a region where the digital watermark is embedded and a region where the dot pattern is added by the add-on method, the digital watermark and the add-on method can coexist.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus and method capable of embedding additional information in one image by using a plurality of methods, and a computer-readable storage medium used for the method and apparatus.

[0002]

2. Description of the Related Art In recent years, the image quality of digital color image forming apparatuses such as printers and copiers has been remarkably improved, and high-quality full-color prints can be easily obtained. That is, anyone can obtain required printed matter by image processing using a high-performance scanner, printer, copier, and computer. For this reason, problems such as counterfeiting of bills and securities occur, and there are image forming apparatuses equipped with a forgery prevention function.

[0003] The forgery prevention function generally has both a forgery tracking function and a bill recognition function. The forgery tracking function, as a general realization method, is to print a regular pattern representing the model code of the recording device at the time of printing, and when a forged bill is discovered, the dot pattern struck on the bill There is a so-called add-on method in which a model number is determined and a recording model from which the model number is output is specified. Since this dot pattern is printed on all the images to be output, it is general that the dot pattern is printed in yellow, which has the lowest visibility.

In recent years, a technology called digital watermark for protecting copyright of digital information has been known. General digital watermarking technology secretly converts the value of digitized data into copyright information, user information,
And various identification numbers. By extracting the digital watermark from the data, copyright information, user information, identification information, and the like can be obtained, and illegal copying can be tracked.

The first condition required for a digital watermark is that the embedded information cannot be perceived by humans, that is, the embedded digital information can be embedded with reduced quality deterioration (quality). The second condition is that the information embedded in the digital information remains, that is, the embedded information is not lost even by editing or attack such as data compression or filtering (resistance). The third condition is that the amount of information that can be embedded can be selected according to the application (information amount).

The following method is known as a specific method. In the case of a multi-valued still image, a method for embedding a digital watermark can be roughly classified into two methods, a method for embedding in a spatial domain and a method for embedding in a frequency domain, and the following various methods are known.

As an example of a method of embedding in a space area, an IBM method (W.Be
nder, D .; Gruhl, N .; Morimoto, T
echniques for Data Hidin
g, "Proceedingsof the SPI
E, San Jose CA, USA, February
y 1995) and G.S. B. Rhoads, W.C. Lin
n: “Steganography method e
mploying embedded "USP Pat
entNumber5, 636, 292 and the like.

As an example of the method of embedding in the frequency domain,
As a method using the discrete cosine transform, NTT schemes (Nakamura, Ogawa, Takashima, "Digital watermarking scheme in the frequency domain for copyright protection of digital images", SCI
S'97-26A, January 1997), as well as the method of Defense University (Onishi,
Oka, Matsui, "Watermark Signature Method for Images Using PN Sequence",
SCIS '9726B, January 1997) and the method using Mitsubishi's and Kyushu University's methods (Ishizuka, Sakai, Sakurai, "Using the discrete wavelet transform," experiments on the security and reliability of digital watermarking technology using wavelet transform. , SCIS '97 -26D, January 1997) and Matsushita's method ("Digital Watermark Based on Wavelet Transform-Robustness to Image Compression and Transformation-", Inoue, Miyazaki, Yamamoto, Katsura, SCI
S'98-3.2. A, January 1998).

It is difficult for such a digital watermarking technique to have resistance to all editing and attacks while minimizing image quality deterioration. Therefore, there is a technique that has a strong resistance only to editing and attack such as image compression and image cutting that are often performed on digital images, and a so-called print resistance that can detect digital watermark information even when a digital image is printed. In many cases, a digital watermarking technique that is resistant to specialized resistance, such as a technique, is developed.

[0010]

The addition of information for tracking counterfeit bills in the related art is mainly realized by the above-mentioned add-on method, and has not been used together with a digital watermark technique for a still image or the like. Further, a method of combining an add-on method and a digital watermarking method for a print image has not been proposed so far.

The present invention has been made in view of the above-mentioned circumstances, and a digital image or a printed image can be protected according to various uses by using a combination of an add-on method and a digital watermarking method. It is intended to be.

[0012]

In order to achieve the above object, in an image processing apparatus according to the present invention, first signal adding means for adding a predetermined signal to a multi-valued digital image, There is provided a second signal adding means for adding a predetermined signal to a binary digital image obtained by binarizing the output of the first signal adding means.

In another image processing apparatus according to the present invention, a first signal extracting means for extracting a predetermined signal from a binary digital image, and an output from the first signal extracting means is multi-valued. Second signal extracting means for extracting a predetermined signal from the obtained multivalued digital image.

Further, in the image processing method according to the present invention, a first signal adding procedure for adding a predetermined signal to a multi-valued digital image, and an output of the first signal adding procedure is binarized. A second signal adding procedure for adding a predetermined signal to the obtained binary digital image.

Further, in another image processing method according to the present invention, a first signal extraction procedure for extracting a predetermined signal from a binary digital image, and an output by the first signal extraction procedure is multi-valued. A second signal extraction procedure for extracting a predetermined signal from the obtained multi-valued digital image.

In the storage medium according to the present invention,
A first signal addition process for adding a predetermined signal to a multi-valued digital image; and a predetermined signal for a binary digital image obtained by binarizing an output of the first signal addition process. And a program for executing a second signal addition process for adding

In another storage medium according to the present invention, a first signal extraction process for extracting a predetermined signal from a binary digital image and an output obtained by the first signal extraction process are obtained by multi-leveling. And a second signal extracting process for extracting a predetermined signal from the obtained multi-valued digital image.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing an embedding section of an image processing apparatus according to a first embodiment of the present invention. In FIG. 1, an invisible electronic watermark is embedded in a multi-valued input image 10 by an electronic watermark embedding unit 11 that embeds an electronic watermark in the still image described above. This digital watermark embedding process may be performed on a multi-valued digital image, and may be performed at any time, not just before printing. As a method of embedding the digital watermark, for example, Japanese Patent Laid-Open No. 2000-13
Embedding of a digital watermark in a frequency component as disclosed in, for example, Japanese Patent No. 587 is applied.

Next, when converting the multi-valued image in which the digital watermark is embedded into a binary image and printing the binary image, the add-on adding unit 12 adds a specific dot called the add-on method to the binary image. After adding the pattern 2
An output image 13 of the value is obtained. In addition, this add-on method,
Any method may be used as long as information can be embedded in a binary image of each color. For example, a method disclosed in JP-A-6-334841 is applied.

In FIG. 1, a digital watermark embedding unit 1
1 and the add-on adding unit 12 are directly linked, but the processing by the digital watermark embedding unit 11 can be performed at any time. Further, since the add-on adding section 12 is performed immediately before printing by a printer, a copying machine, or the like, various image processing means (not shown) including a conversion process from a digital image to a print image can be provided therebetween.

At this time, as shown in FIG. 2A, an area for embedding a digital watermark when one image is a multi-valued image, and an area for adding a dot pattern by an add-on method for a binary image. , The digital watermark and the add-on method can coexist. FIG.
In FIG. 2A, the area in which the digital watermark is embedded and the add-on addition area are divided into two parts, but as shown in FIG. 2B, the image is divided into a plurality of arbitrary spaces, and the digital watermark and the add-on are added. May be determined. In FIG. 2B, for example, a portion surrounded by a dotted line is an add-on addition region, and the other portion indicates a digital watermark embedding region.

Accordingly, since the area to which the add-on dot pattern is added is predetermined, embedding a multi-valued digital watermark in the other area can realize compatibility with the conventional add-on method. That is, the processing by the digital watermark embedding unit 11 of FIG. 1 is performed on an area where an electronic watermark is embedded in the input image, and the add-on processing by the add-on adding unit 12 is performed on the add-on added area.

The process of extracting the digital watermark information and the dot pattern of the add-on is performed as shown in FIG. 3, a binary input image (corresponding to the output image 13 in FIG. 1) 30 extracts a dot pattern added by an add-on extraction unit 31. In this case, since the digital watermark is invisible information and the area is divided, normal add-on extraction can be performed without affecting the add-on pattern.

Next, the binary image extracted by the add-on is converted into a multi-valued image, and the digital watermark extracting unit 32 extracts a digital watermark from a predetermined area of the multi-valued image, thereby obtaining output information 33. . Also in this case, since the area is divided, the digital watermark can be extracted without being affected by the add-on.

If the digital watermark used here is a digital watermarking method having print durability, the watermark information remains even for the printed image. Therefore, any information other than the information defined by the specific dot pattern of the conventional add-on method can be embedded in the print image as digital watermark information.

If the digital watermark to be used is a digital watermark technique having resistance to a digital image, the digital watermark embedding processing does not need to be performed immediately before printing. Of the digital image, and the add-on method can protect the copyright of the printed image of the digital image.

Furthermore, if digital watermarks having digital image resistance and print resistance, or digital watermarks having various resistances are combined, various protections including prevention of forgery from digital images to print images can be realized according to the application. it can.

(Second Embodiment) In the first embodiment described above, the case where the embedding of the image is made different in order to make the digital watermarking technique and the add-on system coexist has been described. In the present embodiment, a case will be described in which the color space differs between the digital watermark and the add-on.

Generally, a print image is composed of C (cyan), M (magenta), Y (yellow), and BK (black) colors. Among them, the dot pattern addition of the add-on is performed by Y. Therefore, if the digital watermark embedding is performed in another color space C, M, or BK, the add-on and the digital watermark can be distinguished, and both can coexist.

Normally, a digital image is processed in a color space of R (red), G (green), and B (blue), but between R, G, B and C, M, Y, BK. Has a predetermined conversion relationship according to the printing model such as a printer.

FIG. 4 shows an embedding processing section according to this embodiment. In FIG. 4, a multi-valued digital input image 40 is shown.
Is converted by the color conversion unit 41 into a color space (C, M, Y, B) for printing.
K), and then the digital watermark embedding unit 4
2, a multi-value digital watermark embedding process is performed on the image of the selected color of C, M, and BK. The output is inversely converted by the inverse conversion unit 43 to output an image in which a digital watermark is embedded. Next, when printing the image in which the digital watermark is embedded, binarization is performed by the add-on adding section 44, and further, a specific dot pattern is added in yellow by a binary add-on method, and then the binary is added. Output image 45
Get.

In FIG. 4, although the inverse conversion unit 43 and the add-on addition unit 44 are directly connected, a series of processes of color conversion, digital watermark embedding, and inverse conversion are multi-valued digital watermark embedding processes. It only needs to be performed on the digital image, and can be performed at any time.Add-on is performed immediately before printing by a printer or copier, so during that time, the conversion process from the digital image to the print image must be performed again. Various image processing means (not shown) can be provided.

The process of extracting the digital watermark information and the dot pattern of the add-on is performed as shown in FIG. FIG.
In the binary input image (corresponding to the output image 45 in FIG. 4) 50, an add-on extraction unit 51 performs dot pattern extraction by add-on. In this case, since the digital watermark is invisible information and the color space is divided, normal add-on extraction can be performed without affecting the add-on pattern.

Next, color conversion into C, M, and BK is performed by the color conversion unit 52, and digital watermark information is extracted by the digital watermark extraction unit 53 in the color space, so that output information 54 is obtained.

According to the resistance of the digital watermark used here,
Obviously, various protections from digital images to printed images can be realized as shown in the first embodiment.

(Third Embodiment) In the present embodiment,
The case where the information is distinguished by making the frequency component of the component to be digitally watermarked different from that of the component to be subjected to the add-on will be described. Since the dot pattern of the add-on method is determined, its frequency characteristic can be known in advance. Therefore, when using frequency conversion as a digital watermarking method,
By analyzing the dot pattern of the add-on method in advance by the frequency conversion and setting an area other than the frequency component as an electronic watermark embedding area, it is possible to realize both the add-on method and the electronic watermark.

FIG. 6 shows an embedding processing section according to this embodiment. In FIG. 6, a multi-valued digital input image 60 is shown.
Is frequency-converted by the frequency conversion unit 61, and then the digital watermark embedding unit 62 embeds a digital watermark in a frequency region which is not analyzed by the add-on and has no influence.
The output is inversely converted by the inverse frequency conversion unit 63 to output a digital watermark image. Next, when the digital watermark image is printed, it is converted into a binary image, and an add-on adding section 64 adds a specific dot pattern by an add-on method to obtain an output image 65.

In FIG. 6, although the inverse frequency conversion unit 63 and the add-on addition unit 64 are directly linked, a series of processes of frequency conversion, digital watermark embedding, and inverse frequency conversion are performed as digital watermark embedding processing. This can be done at any time, as long as it is performed on the digital image of the value.Because the add-on is performed immediately before printing with a printer or copier, the conversion from the digital image to the print image is performed in the meantime. Various image processing means (not shown) including processing can be provided.

The process of extracting the digital watermark information and the dot pattern of the add-on is performed as shown in FIG. FIG.
In a binary input image (corresponding to the output image 65 in FIG. 6) 70, an add-on extraction unit 71 extracts a dot pattern by an add-on. In this case, since the digital watermark is invisible information and the frequency domain is divided, normal add-on extraction can be performed without affecting the add-on pattern.

Next, after the frequency conversion is performed by the frequency conversion section 72, the digital watermark information is extracted by the digital watermark extraction section 73 in a predetermined frequency region, thereby obtaining an output image 74.

According to the resistance of the digital watermark used here,
Obviously, various protections from digital images to printed images can be realized as shown in the first embodiment.

(Fourth Embodiment) Several digital watermarking methods for binary still images such as print images have been conventionally proposed (Koshio Matsui: "Basics of Digital Watermarking", Morikita Publishing, No. See Chapter 2, "Digital Watermarking on Binary Images."

Since these methods target binary images, they are often performed at the time of printing or the like. Therefore, it is conceivable to use an electronic watermarking method for a binary still image instead of the add-on method. In this case, the combination of the binary digital watermarking method and the above-described multi-valued digital watermarking method is also similar to the method of place division, color division, frequency division, or the like as shown in the first to third embodiments. It is clear that this can be achieved by:

Therefore, the present embodiment is realized by using each of the add-on adding units in the first to third embodiments as a binary digital watermark embedding unit and each add-on extracting unit as a binary digital watermark extracting unit. can do.

(Fifth Embodiment) In the present invention, only an apparatus and a method for realizing each of the above embodiments and a method for performing a combination of the methods described in the first to fourth embodiments are used. The present invention is not limited to this. A program code of software for realizing each embodiment is supplied to a computer (CPU or MPU) in the above system or apparatus, and the computer of the system or apparatus is supplied in accordance with the program code. The present invention also includes a case where each embodiment is realized by operating the above-described various devices.

In this case, the program code itself of the software realizes the functions of the embodiments, and the program code itself and means for supplying the program code to the computer, specifically, A storage medium storing the program code is included in the scope of the present invention.

As a storage medium for storing such a program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, magnetic tape, nonvolatile memory card, ROM and the like can be used.

In addition to the case where the computer controls various devices according to only the supplied program code to realize the functions of the respective embodiments, the program code operates on the computer. Such a program code is also included in the scope of the present invention when each embodiment is realized in cooperation with an OS (Operating System) or other application software.

Further, after the supplied program code is stored in a memory provided on a function expansion board of a computer or a function expansion unit connected to the computer, the function expansion board or the function is stored based on the instruction of the program code. The scope of the present invention also includes a case where a CPU or the like provided in the storage unit performs part or all of actual processing, and the processing realizes each embodiment.

[0050]

As described above, according to the present invention,
The conventionally used add-on method and digital watermarking technology can coexist. This makes it possible to embed / extract additional electronic watermark information even in a copying machine or a printer adopting the add-on method.

If the digital watermark to be used is a print-resistant method, the watermark information remains in the printed image, so that any arbitrary information other than the information defined by the specific dot pattern of the conventional add-on method is used. Can be embedded as electronic watermark information in a print image without changing an apparatus or the like adopting the add-on method.

When the digital watermark to be used is a digital watermark having resistance to a digital image, copyright protection for a digital image on a computer or a network is performed by a digital watermarking technique, and a digital image is printed on a printed image by an add-on method. Rights protection.

Furthermore, by combining digital watermarks having digital image resistance and printing resistance, or digital watermarks having various resistances, protection of digital images and printed images according to various uses can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embedding processing unit of an image processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating image area division according to the first embodiment.

FIG. 3 is a block diagram illustrating an extraction processing unit of the image processing device according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating an embedding processing unit of an image processing apparatus according to a second embodiment of the present invention.

FIG. 5 is a block diagram illustrating an extraction processing unit of an image processing device according to a second embodiment of the present invention.

FIG. 6 is a block diagram illustrating an embedding processing unit of an image processing device according to a third embodiment of the present invention.

FIG. 7 is a block diagram illustrating an extraction processing unit of an image processing device according to a third embodiment of the present invention.

[Explanation of symbols]

 10, 30, 40, 50, 60, 70 Input image 11, 42, 62 Digital watermark embedding unit 12, 44, 51 Add-on adding unit 31, 51, 71 Add-on extracting unit 32, 53, 73 Digital watermark extracting unit 43, 63 Inverse converter 41, 52 Color converter 61, 72 Frequency converter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G06T 1/00 500 G03G 21/00 554 5C077 H04N 1/40 H04N 1/40 Z 9A001 (72) Inventor Makita Tsuyoshi 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) in Canon Inc. DB08 DC25 DC36 5C076 AA14 BA06 5C077 LL14 MP01 MP08 PP23 PP33 PP49 PP55 PP65 RR02 9A001 EE03 HH23 JJ35 KK42

Claims (22)

[Claims] 1. A first signal adding means for adding a predetermined signal to a multi-valued digital image, and a binary digital image obtained by binarizing an output of the first signal adding means. An image processing apparatus provided with second signal adding means for adding a predetermined signal to the image processing apparatus. 2. The image processing apparatus according to claim 1, wherein said second signal adding means adds an identification signal based on a dot pattern of a predetermined color. 3. The image processing apparatus according to claim 1, wherein said second signal adding means embeds digital watermark information in a binary print image. 4. The image processing apparatus according to claim 1, wherein said first signal adding means embeds digital watermark information in a multi-valued still image. 5. The image processing apparatus according to claim 1, wherein each predetermined signal added by said first and second signal adding means is added to a different area in an image. 6. An image processing apparatus according to claim 1, wherein said predetermined signals added by said first and second signal adding means are added in different colors. 7. An image processing apparatus according to claim 1, wherein said predetermined signals added by said first and second signal adding means have different frequency components. 8. An image processing apparatus according to claim 1, wherein said first signal adding means adds digital watermark information having print durability. 9. The image processing apparatus according to claim 1, wherein said first signal adding means adds robust digital watermark information to the digital image. 10. The digital watermark information to be embedded is:
The image processing apparatus according to claim 4, wherein the information is information on a print image to be output. 11. The digital watermark information to be embedded is:
6. The image processing apparatus according to claim 5, wherein the information is information relating to a digital image. 12. A first signal extracting means for extracting a predetermined signal from a binary digital image, and a predetermined signal from a multi-valued digital image obtained by multi-leveling the output of the first signal extracting means. An image processing apparatus comprising: a second signal extracting unit that extracts a signal. 13. The image processing apparatus according to claim 12, wherein said first signal extracting means extracts an identification signal based on a dot pattern of a predetermined color. 14. The apparatus according to claim 12, wherein said first signal extracting means extracts digital watermark information. 15. An image processing apparatus according to claim 12, wherein said second signal extracting means extracts digital watermark information. 16. The image processing apparatus according to claim 12, wherein said first and second signal extracting means extract each predetermined signal from different regions in the image. 17. The image processing apparatus according to claim 12, wherein said first and second signal extracting means extract each predetermined signal as a different predetermined color. 18. The image processing apparatus according to claim 12, wherein said first and second signal extracting means extract each predetermined signal as a different predetermined frequency component. 19. A first signal adding procedure for adding a predetermined signal to a multi-valued digital image, and a binary digital image obtained by binarizing an output of the first signal adding procedure. A second signal addition procedure for adding a predetermined signal to the image processing method. 20. A first signal extraction procedure for extracting a predetermined signal from a binary digital image, and a predetermined signal extraction procedure based on a multi-valued digital image obtained by multi-level output of the first signal extraction procedure. A second signal extraction procedure for extracting a signal. 21. A first signal addition process for adding a predetermined signal to a multi-valued digital image, and a binary digital image obtained by binarizing an output of the first signal addition process. A computer-readable storage medium storing a program for executing a second signal adding process for adding a predetermined signal to the computer. 22. A first signal extraction process for extracting a predetermined signal from a binary digital image, and a predetermined signal extraction process from a multivalued digital image obtained by converting the output of the first signal extraction process into a multivalued image. A computer-readable storage medium storing a program for executing a second signal extraction process for extracting a signal.