JP2000078391A - Printing method and device and recording medium thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To embed auxiliary information in image data for printing at the time of reproducing the image data, in which the auxiliary information is deeply ciphered and embedded as printing images. SOLUTION: In this printing method, auxiliary information F is read in an auxiliary information read means 12 from image data S0', in which the auxiliary information F is deep layer ciphered and embedded, the image data S0'' from which the auxiliary information F is separated are obtained, and they are inputted to a pattern embedding conversion means 3. In the pattern embedding conversion means 3, the image data S0'' are converted into image data S1' (CMYK) for printing, so as to almost conditionally color-equalize a part where the auxiliary information F is buried and the other part in the image data S0''. The image data S1 are printed on a paper sheet in a printing means 4 as visible images. In the printed matter, although the embedded auxiliary information F can not be recognized visually under normal light source, the embedded auxiliary information F can be recognized visually under a special light source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing method and apparatus for converting image data in which supplementary information is deeply encrypted and embedded into printing data for printing, and a program for causing a computer to execute the printing method. The present invention relates to a computer-readable recording medium having recorded therein.

[0002]

2. Description of the Related Art When a photographic original is used as a printing original, the photographic original is read by a scanner or the like to read RGB images.
Digital data consisting of three color components is obtained, and color separation data for printing is created based on the digital data. As color components of the separation data, in addition to C (cyan), M (magenta), and Y (yellow), which are the three primary colors of normal printing, K is added to reproduce a shadow portion of a character or a subject. In some cases, four color components are used. Further, when the color reproduction range is wide, or when printing is performed so that a vivid image is obtained, six or more color components including G (green) and O (orange) inks are used. is there. Here, when converting digital data composed of RGB color components into CMYK (or CMYGOK) color components, conversion parameters are set so as to reproduce a color faithful to a document. At this time, in consideration of printing stability, ink cost, and the like, various parameters for optimizing the method of inserting K in particular are used.

[0003] On the other hand, since photo manuscripts and printed materials themselves are copyrighted because they are valuable as creations, it is necessary to prevent their unauthorized duplication. In addition, some printed materials, such as banknotes, securities, and various types of tickets, can themselves be exchanged for money. In particular, such printed materials need to completely prevent unauthorized duplication.
However, with the spread of color scanners and printers that can obtain high-quality images at low cost, an environment in which color prints can be easily reproduced is rapidly being formed.

[0004] In order to prevent the above-mentioned illegal duplication, there are a method of embedding a watermark on paper, a method of embedding UV ink or a metal belt, and various special printing methods for the purpose of preventing counterfeiting of micro-characters and the like, especially banknotes. Is being done.

Various techniques have been proposed for embedding the copyright information and the like of image data in the image data by deep encryption (for example, Japanese Patent Application Laid-Open Nos. 8-289159 and 8-129159).
0-108180, JP-A-9-214636, etc.).
This method involves embedding authentication information and copyright information in a redundant portion of data. For example, it is not possible to confirm the embedded information only by reproducing the image data, but a device for reading the information is used. Using software and software, information embedded in data can be read and displayed. The details of this deep encryption are described in various documents (for example, “Digital Watermark, Koshio Matsui, Oplus E
No. 213, August 1997).

As such a deep encryption method, various methods such as a pixel space use type, a quantization error use type, and a frequency domain use type are known. The pixel space utilization type extracts a plane of, for example, 3 × 3 pixels near the target pixel, and
This is a method of embedding supplementary information in bits. The quantization error utilization type focuses on a quantization error generated in the process of compressing image data, and controls the quantization output to an even number and an odd number with 0 and 1 of the bit sequence of the incidental information, so that an apparent quantization noise is generated. Embedded in the image data.
For this quantization error utilization type, see "Image deep encryption".
(Koshio Matsui, Morikita Publishing, 1993) describes the details. The frequency domain utilization type is a method of embedding supplementary information in a visually insensitive frequency domain on an image domain. For example, since the high-frequency component in the image is a visually insensitive area, the image data is decomposed into a plurality of frequency bands, the additional information is embedded in the high-frequency band, and the additional information is embedded by reconstructing the image data. be able to. As for human visual characteristics, color difference and saturation information generally have lower gradation discrimination ability than luminance information, and there is an area where recording that is invisible to the difference between luminance and color difference or saturation information is possible. Exists. Therefore, additional information can be embedded in this area.

[0007] Other methods include embedding incidental information in a bit plane having a poor S / N ratio as noise by embedding noise as redundancy, and embedding information in information blocks within a certain range of pixel blocks (spaces). A method of embedding a quantization error in the case where the amount of data information is reduced due to encoding when performing data compression is exemplified.

[0008]

As described above, when printing and reproducing the image data in which the additional information has been deeply encrypted and embedded, the image data for printing is printed while the additional information is embedded. When printing is performed by converting the information into the image, the additional information appears as noise on the printed matter, and the image is deteriorated. In this case, it is conceivable to separate the additional information from the image data. However, since the additional information is also removed from a printed matter obtained by printing, the additional information cannot be attached to the printed matter.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended to cause a computer to execute a printing method and apparatus and a printing method capable of performing printing with accompanying information attached to a printed matter without deteriorating an image. It is an object of the present invention to provide a computer-readable recording medium on which the program is recorded.

[0010]

A printing method according to the present invention is a printing method that converts image data in which supplementary information is deeply encrypted by a predetermined deep encryption method and is embedded into print data, and performs printing. And separating the collateral information from the image data to obtain separated image data, converting the separated image data into the print data, and converting the collateral information into the print data with the predetermined deep encryption method. Is characterized by embedding by a different method.

Here, the embedding of the additional information in the print data may be performed not only for the converted print data but also at the same time as the conversion of the separated image data to the print data.

In the printing method according to the present invention,
It is preferable that the data of the supplementary information part in which the supplementary information is embedded in the print data is modulated with substantially the same color as the data of the other part to obtain the print data in which the supplementary information is embedded.

[0013] Here, "modulate by applying a conditionally equal color" means that the image is perceived as the same color under a certain observation light source, but is perceived as a different color under a specific observation light source. Modulation of data. Therefore, it is not possible to perceive the color difference between the pattern and the other part under the observation light source that is usually used, but to perceive the color difference between the two under the special observation light source. By setting to, the pattern can not be visually recognized when the printed matter is observed under a normal light source,
The pattern can be visually recognized only when observed under a special light source.

In the printing method according to the present invention,
The printing data is composed of CMYK four-color component data. By changing at least the value of the K data of the four-color component data, the data of the supplementary information portion and the data of the other portion can be substantially adjusted. It is preferable to make the colors match.

[0015] A printing apparatus according to the present invention is a printing apparatus for performing printing by converting image data in which supplementary information is deeply encrypted by a predetermined deep encryption method and embedded therein to print data, and performing printing. A separating unit that separates the incidental information to obtain separated image data, a converting unit that converts the separated image data into the print data, and the predetermined deep encryption method that converts the incidental information into the print data. And embedding means for embedding by a different method.

In the printing apparatus according to the present invention,
The embedding unit modulates the data of the supplementary information in which the supplementary information is embedded in the print data, and modifies the data of the supplementary information by substantially the same color as the data of the other part to convert the print data in which the supplementary information is embedded. It is preferably a means for obtaining.

In this case, the printing data is a commercial
YK four-color component data.
It is preferable that the means for changing the value of at least the K data in the color component data so that the data of the supplementary information portion and the data of the other portion have substantially the same color.

The printing method according to the present invention may be provided by being recorded on a computer-readable recording medium as a program for causing a computer to execute the method.

[0019]

According to the present invention, when additional information is separated from embedded image data in which the additional information is deeply encrypted by a predetermined deep encryption method and converted to print data, the additional print information is used. The printing is performed by embedding the additional information in the data by a method different from a predetermined deep encryption method. For this reason, compared to the case where the image data in which the additional information is embedded is directly converted into print data and printing is performed, the additional information does not appear as noise, thereby obtaining a high-quality print image. In addition to this, it is possible to prevent the accompanying information from being separated from the printed matter.

Further, by modulating the data of the supplementary information portion in the print data with substantially the same color as the data of the other portion, and observing the printed material under a certain observation light source, the color of the supplementary information portion and other data are changed. Is perceived as the same color as the color of the part, but under a specific observation light source, the color of the incidental information part is perceived as a color different from the color of the other part. Therefore, the color difference between the additional information part and the other part cannot be visually recognized under the observation light source that is normally used, but the color difference between the two can be visually recognized under the special observation light source. By setting so that it can be performed, the additional information can be embedded in the printed matter so that the additional information cannot be easily visually recognized. As a result, when the collateral information is the copyright information of the printed matter, the copyright information can be embedded in the printed matter without being known to an unauthorized user, and the collateral information can be read under a special observation light source. As a result, the copyright information of the printed matter can be obtained, so that the source of the printed matter can be confirmed.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram showing the configuration of an apparatus for embedding supplementary information in image data used in the embodiment of the present invention. As shown in FIG. 1, this apparatus reads an image from a photo original G and obtains image data S0 (RGB) of three colors of RGB, such as a scanner, and additional information F embedded in the image data S0. An additional information generating means 10 for generating the information and an embedding means 11 for obtaining the image data S0 '(RGB) in which the additional information F is embedded by embedding the additional information F in the image data S0 by deep encryption.

Here, as a method of embedding the supplementary information F in the image data S0 by deep encryption in the embedding means 11, the above-mentioned JP-A-8-289159, 1
Various methods such as the methods described in JP-A Nos. 0-108180 and 9-214636, the pixel space utilization type, the quantization error utilization type, and the frequency domain utilization type can be used.

FIG. 2 is a schematic block diagram showing the configuration of the printing apparatus according to the present embodiment. As shown in FIG.
The printing apparatus according to the embodiment reads the additional information F from the image data S0 'obtained by the apparatus shown in FIG.
Additional information F and image data S from which additional information F is separated
Additional information reading means 12 for obtaining 0 "and image data S0"
And embedding additional information F as a bit pattern and converting image data S0 ″ into CMYK to obtain image data S1 ′ (CMYK) for printing composed of four colors of CMYK and embedded with additional information F. Means 3
And printing means 4 for printing the image data S1 'on paper.

The pattern-embedding conversion means 3 converts the RGB image data S0 'into CMYK printing image data S1'. The conversion characteristics at the time of this conversion are modulated by the bit pattern of the supplementary information F. The image data S
Additional information F is embedded in 1 '. Here, the detailed configuration of the pattern embedding conversion means 3 is shown in FIG. Here, a case where the additional information F is embedded as a binary bit pattern P will be described.

The switch 6 selects which of the two color conversion LUTs 1 and 2 converts the pixel value of a certain pixel in the image data S0 "from RGB to CMYK. This selection is made. This is performed by switching the switch 6 depending on whether the value of the bit pattern P corresponding to the pixel to be converted is 1 or 0. When the value of the bit pattern P is 0, the color conversion L
The switch 6 is switched so that UT1 is selected, and when it is 1, the color conversion LUT2 is selected.

The color conversion LUTs 1 and 2 are CMYK conversion LUTs.
It is created by the creating means 7. Here, the color conversion LUT
Data S obtained by being converted by 1, 2
2 (CMYK) and data S2 '(C'M'Y'K)
Has the relationship shown in the following equation (1).

Lab {CMYK (RGB)} = Lab {C′M′Y′K ′ (RGB)} (1) where Lab {} is a function that gives a CIE colorimetric value of a printed color for CMYK data. And CMYK ()
Is a conversion formula for RGB data to CMYK data.

Here, CMYK and C'M'Y'K '
Is a data pair having the same colorimetric value calculated from the same print color reproduction characteristic description data K by the CMYK conversion LUT creating means 7, that is, a condition-matching color pair. Therefore, although the two data S2 and S2 'obtained by the color conversion LUTs 1 and 2 are different, the printing means 4
Are perceived as the same color on the printed material obtained by the above. Therefore, the pixel value corresponding to the portion of the bit pattern P on the image represented by the image data S0 ″ is converted by the color conversion LUT2, and the pixel value corresponding to the portion other than the bit pattern P is converted by the color conversion LUT1. , Data S2 'and data S2, and form image data S1' based on these, and printing is performed in the printing means 4 based on the image data S1 '. It cannot be perceived by the human eye.

CMYK having such a condition-equal color relationship
Table 1 below shows an example in which data combinations are obtained from the color reproduction characteristics of a four-color offset printing press. The combinations shown in Table 1 were obtained so as to achieve color matching under a standard observation light source having a color temperature of 5000 K, and the values of Lab in Table 1 were obtained under this light source. It should be noted that not only the combinations of the CMYK data for the conditionally equal colors shown in Table 1 but also various other combinations can be used.

[0031]

[Table 1]

When the LUT is created by the CMYK conversion LUT creating means 7, the modulation intensity of the bit pattern P to be embedded can be changed by specifying the parameter H of the modulation intensity. For example, if data A shown in Table 1 above is used as CMYK data and data B is used as C'M'Y'K 'data, the modulation intensity of the bit pattern P becomes relatively small. Accordingly, under such conditions, the supplementary information F is not easily visually recognized even if the observation light source slightly changes, which is suitable for an application where emphasis is placed on invisibility. On the other hand, if the data A shown in Table 1 above is used as CMYK data and the data C is used as C'M'Y'K 'data, the modulation intensity of the bit pattern P becomes relatively large. Therefore, under such a condition, the additional information F embedded under the standard light source cannot be visually recognized, but the auxiliary information F can be easily detected under a different light source. Therefore, it is suitable for applications where importance is placed on detectability.

When the additional information F is a multi-valued bit pattern P, the bit value may be used as the modulation intensity. In this case, the bit pattern P is input to the CMYK conversion LUT creating means 7 as the modulation intensity parameter H, and if the value is large, data with a large K value is selected from the group of conditional color matching, and if the value is small, the data is proportional to it. By selecting data with a small K value, a pattern having a gradation corresponding to the bit pattern P can be embedded.

Next, the operation of this embodiment will be described. FIG. 4 is a flowchart illustrating processing performed in the present embodiment. First, the photo original G is read by the image reading means 1, and RGB image data S0 is obtained (step S1). On the other hand, the additional information generating means 10 generates additional information F for deep encryption and embedding in the image data S0 (step S2). Then, the embedding unit 11 performs the deep encryption on the incidental information F and embeds the incidental information F in the image data S0 to obtain image data S0 'in which the incidental information F is embedded (step S3).

Next, in the printing apparatus, the image data S
0 'is input to the supplementary information reading means 12, and the image data S
0 'is read out of the additional information F embedded and embedded in the image data S from which the additional information F is separated.
0 "is obtained (step S4). The supplementary information F and the image data S0" are input to the pattern embedding conversion means 3 (step S5). In the pattern embedding conversion unit 3, the CMYK conversion LUT generation unit 7 performs color conversion LUT 1, color conversion LUT 1 based on the supplementary information F and the modulation intensity parameter H.
LUT2 is created (step S6). Then, for the pixel whose image data S0 "corresponds to the supplementary information F, the image data S2 '(C'M'Y'
K ′), and for pixels that do not correspond to the supplementary information F, the image data S2 (CMYK) is converted by the color conversion LUT1.
(Step S7). Then, the image data S
2, S2 ', image data S1' (CMYK) in which the incidental information F is embedded as a bit pattern is created (step S8). Image data S created in this way
1 'is input to the printing means 4, where it is printed as a visible image on paper (step S9).

As described above, in this embodiment, the image data S0 '(RGB) is converted to the image data S1' for printing.
At the time of conversion to (CMYK), the pixels corresponding to the additional information F to be embedded are modulated in such a manner that the pixels corresponding to the other parts are color-matched with the other parts, so that the additional information part can be obtained even when the printed matter is observed under a certain observation light source. And the color of the other part will be perceived as the same color, but the color of the incidental information part will be perceived as a color different from the color of the other part under a specific observation light source. Become. Therefore, the embedded additional information F cannot be visually recognized under a normal light source, but the additional information F can be visually recognized only under a special light source. As a result, in order to prevent unauthorized duplication. This information can be embedded in the printed matter so that it cannot be easily perceived.

Since the additional information F is embedded in the image data S0 ', when the image data S0' is reproduced, the additional information F appears as noise in image quality.
The image quality is degraded. On the other hand, in the present embodiment, the additional information F
And the additional information F is embedded as a bit pattern in the image data S0 ″ from which the additional information F has been separated.
Since it is converted into image data S1 'for printing,
The additional information F does not appear as noise, and thus a high-quality print image can be obtained.

In the above embodiment, CMYK
Has been described in the case of printing in four colors of CMYGOK, but also in the case of printing in six colors of CMYGOK to which orange (O) and green (G) are added.
Can be embedded. In this case, for example, by changing the ratio between CY and G or changing the ratio between MY and O, the additional information F can be embedded in a conditionally equal color, but as shown in Table 1 above, K By changing the value, it is also possible to make the colors equal to the condition.

In the above-described embodiment, the additional information F is used as a bit pattern, and the bit pattern portion and the portion other than the bit pattern are color-matched and embedded in the print image data S1 '. However, the present invention is not limited thereto, and the supplementary information F may be inserted into a print sheet as a watermark, or the supplementary information F may be printed with UV ink. In this case, the incidental information F can be visually recognized by irradiating ultraviolet rays. Further, the supplementary information F may be printed and embedded in the metal belt,
The supplementary information F may be embedded as micro characters. Further, the supplementary information F may be embedded in the header of the image data S1 'for printing.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a configuration of an auxiliary information embedding device for obtaining image data used in an embodiment of the present invention.

FIG. 2 is a schematic block diagram illustrating a configuration of a printing apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic block diagram showing a detailed configuration of a pattern embedding conversion unit.

FIG. 4 is a flowchart illustrating processing performed in the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading means 3 Pattern embedding conversion means 4 Printing means 6 Switch 7 CMYK conversion LUT creation means 10 Additional information generation means 11 Embedding means 12 Additional information reading means

Claims (9)

[Claims] 1. A printing method for performing printing by converting image data in which supplementary information is deeply encrypted by a predetermined deep encryption technique and embedded into print data, and printing the supplementary information from the image data. Printing by separating the separated image data into the print data, and embedding the incidental information in the print data by a method different from the predetermined deep encryption method. Method. 2. The data of the supplementary information part in which the supplementary information is embedded in the print data is modulated with substantially the same color as the data of the other part to obtain print data in which the supplementary information is embedded. The printing method according to claim 1, wherein: 3. The printing data is composed of four color component data of CMYK, and by changing at least the value of K data of the four color component data, the data of the additional information part and the data of the other part are changed. 3. The printing method according to claim 2, wherein the data and the data are made substantially equal in color. 4. A printing apparatus for performing printing by converting image data in which supplementary information is deeply encrypted by a predetermined deep encryption method and embedded therein to print data, and printing the supplementary information from the image data. Separating means for separating to obtain separated image data; converting means for converting the separated image data into the printing data; and embedding the incidental information in the printing data by a method different from the predetermined deep encryption method. A printing apparatus comprising an embedding unit. 5. The embedding unit modulates data of an additional information portion of the print data, in which the additional information is embedded, with substantially the same color as data of another portion to embed the additional information. 5. The printing apparatus according to claim 4, wherein the printing apparatus obtains the printing data. 6. The printing data comprises CMYK four-color component data, and the embedding means includes at least K of the four-color component data.
6. The printing apparatus according to claim 5, wherein the printing apparatus is means for changing the value of the data so that the data of the supplementary information portion and the data of the other portion are substantially equal in color. 7. A computer storing a program for causing a computer to execute a printing method of converting embedded image data into which printing is performed by converting embedded image data into deep print data by a predetermined deep encryption method. A readable recording medium, the program comprising: a step of separating the incidental information from the image data to obtain separated image data; a step of converting the separated image data into the print data; Embedding the additional information in the data by a method different from the predetermined deep-layer encryption method. 8. The embedding step includes embedding the additional information in the print data by modulating the data of the additional information portion in which the additional information is embedded with substantially the same color as the data of the other portion. 8. The computer-readable recording medium according to claim 7, wherein the procedure is a step of obtaining print data. 9. The printing data includes CMYK four-color component data, and the embedding step includes changing at least the value of the K data in the four-color component data to obtain data of the additional information portion. 9. The computer-readable recording medium according to claim 8, wherein the procedure is a step of substantially equalizing the color of the data of the other portion.