JP3474112B2 - Printing method and apparatus, and recording medium - Google Patents

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 incidental information is deeply encrypted and embedded, into printing data, and printing, and a program for causing a computer to execute the printing method. The present invention relates to a computer-readable recording medium in which is recorded.

[0002]

2. Description of the Related Art When a photo original is used as an original for printing, the photo original is read by a scanner or the like and RGB
The digital data composed of the three color components is obtained, and the color separation data for printing is created based on the digital data. As the color component of this color 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 the shadow portion of characters and subjects. In some cases, four color components are used. Also, when the color reproduction range is wide, or when 6 or more color components including G (green) and O (orange) inks are used for printing so as to obtain a vivid image, is there. Here, when converting digital data composed of RGB color components into CMYK (or CMYGOK) color components, conversion parameters are set so that colors faithful to the original can be reproduced. At this time, various parameters are used in particular for optimizing how to insert K in consideration of printing stability, ink cost, and the like.

On the other hand, since photographic originals and printed materials themselves are copyrighted because they are valuable as creations, it is necessary to prevent their unauthorized copying. Further, some printed matters such as banknotes, securities, and various tickets can be redeemed for cash, and it is particularly necessary to completely prevent illegal duplication of such printed matters.
However, with the widespread use of inexpensive color scanners and printers capable of obtaining high-quality images, an environment in which color printed matter can be easily duplicated is being rapidly formed.

In order to prevent the above-mentioned illegal duplication, there are various methods such as a method of watermarking paper, a method of embedding UV ink or a metal belt, and various special printing methods for preventing forgery of banknotes such as micro characters. Has been done.

Further, various methods have been proposed for deeply encrypting the copyright information of image data and the like into image data and embedding it (see, for example, Japanese Patent Laid-Open No. 8-289159 and No. 1-289159).
0-108180, JP-A-9-214636, etc.).
In this method, by embedding authentication information or copyright information in a redundant portion of data, it is not possible to confirm the embedded information only by reproducing the image data, but a device for reading the information. The information embedded in the data can be read out and displayed by using the or software. Details of this deep encryption are described in various documents (for example, “Digital Watermark, Kushio Matsui, O plus E”).
No. 213, August 1997).

Various methods such as a pixel space utilization type, a quantization error utilization type, and a frequency domain utilization type are known as such deep encryption techniques. In the pixel space utilization type, a plane of, for example, 3 × 3 pixels near the target pixel is taken out,
This is a method of embedding supplementary information in bits. The quantization error utilization type pays attention to the quantization error generated in the process of compressing image data, and controls the quantization output to be an even number and an odd number with 0 and 1 of the bit sequence of the incidental information, and apparently quantization noise. Is a method of embedding the incidental information in the image data.
For this quantization error utilization type, see "Image deep encryption".
(Kushio Matsui, Morikita Publishing Co., 1993) for details. The frequency domain utilization type is a method of embedding additional information in a frequency domain that is visually insensitive in the 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 incidental information is embedded in the high frequency band, and the incidental information is embedded by reconstructing the image data. be able to. Further, as a human visual characteristic, the color difference and the saturation information generally have lower gradation discrimination ability than the luminance information, and there is an area in which the invisible recording is possible at the difference between the luminance and the color difference or the saturation information. Exists. Therefore, additional information can be embedded in this area.

In addition, a method of embedding incidental information in a bit plane having a poor S / N as an image by making noise redundantly embedded, or a method of embedding it in redundancy of information change in a certain range of pixel blocks (spaces), There is a method of embedding in a quantization error when the amount of data information is degenerated by encoding when performing data compression.

[0008]

As described above, when the image data in which the incidental information is deep-encrypted and embedded is printed and reproduced, the image data for printing the image data while the incidental information is embedded is printed. When the data is converted to and printed, the incidental information appears on the printed matter as noise and the image deteriorates. In this case, it is conceivable to separate the incidental information from the image data, but since the incidental information is also removed from the printed matter obtained by printing, the incidental information cannot be attached to the printed matter.

The present invention has been made in view of the above circumstances, and makes a computer execute a printing method and apparatus and a printing method capable of performing printing without degrading an image and accommodating supplementary information to a printed matter. It is an object of the present invention to provide a computer-readable recording medium in which the program is recorded.

[0010]

A printing method according to the present invention is a printing method in which image data in which incidental information is deep-encrypted by a predetermined deep-encryption method and embedded is converted into print data for printing. Then, the additional information is separated from the image data to obtain separated image data, the separated image data is converted into the printing data, and the additional information is added to the printing data by the predetermined deep encryption method. Is characterized by being embedded by different methods.

Here, the supplementary information may be embedded in the print data not only in the converted print data but also simultaneously with the conversion of the separated image data into the print data.

In the printing method according to the present invention,
It is preferable to obtain data for printing in which the supplementary information is embedded by modulating the data of the supplementary information portion in which the supplementary information is embedded in the print data so that the data of the other portion has substantially the same color. In this case, it is preferable that the number of color components of the printing data is larger than the number of color components of the image data.

Here, "conditionally color-match and modulate" means that the colors are perceived as the same color under a certain observation light source, but are perceived as different colors under a specific observation light source. Modulates data. Therefore, the condition for color matching cannot be perceived as a difference in color between the pattern and another part under an observation light source that is usually used, but under a special observation light source, a difference in color between the two can be perceived. By setting to, when the printed matter is observed under a normal light source, the pattern cannot be visually recognized,
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, and by changing the value of at least K data of the four-color component data, the data of the additional information portion and the data of the other portion are substantially conditioned. It is preferable that the colors are the same.

A printing apparatus according to the present invention is a printing apparatus for converting image data in which incidental information is deeply encrypted by a predetermined deep encryption method and embedded and converting the image data to print data for printing. A separation means for separating the additional information from the additional information to obtain separated image data; a conversion means for converting the separated image data into the printing data; and a predetermined deep encryption method for the additional information in the printing data. Is equipped with an embedding means for embedding by a different method.

In the printing apparatus according to the present invention,
The embedding means modulates the data of the incidental information portion in which the incidental information is embedded in the print data by performing color matching with the data of the other portion in a substantially equal color to obtain the print data in which the incidental information is embedded. It is preferably a means for obtaining.

In this case, the print data is CM
It is composed of YK four-color component data, and the embedding means stores the four
It is preferable that the data of the incidental information portion and the data of the other portion are substantially equalized in color by changing at least the value of K data of the color component data.

The printing method according to the present invention may be recorded in a computer-readable recording medium and provided as a program to be executed by a computer.

[0019]

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

Further, the data of the incidental information portion in the printing data is modulated by being subjected to a color condition substantially equal to that of the data of the other portion, and when the printed matter is observed under a certain observation light source, the color of the incidental information portion and other Although the color of the part is perceived as the same color, the color of the incidental information part is perceived as a color different from the colors of other parts under a specific observation light source. Therefore, the condition for color matching cannot be visually recognized under the observation light source that is usually used, but the color difference between the supplementary information part and other parts cannot be visually recognized under the special observation light source. By setting so that it can be set, the supplementary information can be embedded in the printed matter so that it cannot be easily visually recognized. Thus, if the supplementary information is used as 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 supplementary information can be read under a special observation light source. Since the copyright information of the printed matter can be obtained, the source of the printed matter can be confirmed.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION 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 incidental information in image data used in the embodiment of the present invention. As shown in FIG. 1, this apparatus includes an image reading unit 1 such as a scanner that reads an image from a photographic document G to obtain image data S0 (RGB) of three colors of RGB, and supplementary information F embedded in the image data S0. The auxiliary information generating means 10 for generating and the embedding means 11 for deeply encrypting and embedding the auxiliary information F in the image data S0 to obtain the image data S0 ′ (RGB) in which the auxiliary information F is embedded are provided.

Here, as a method of deeply encrypting the supplementary information F performed in the embedding means 11 into the image data S0 and embedding it, the above-mentioned Japanese Patent Laid-Open No. 8-289159 and 1).
Various methods such as the method described in 0-108180 and 9-214636, the pixel space utilization type, the quantization error utilization type, the frequency domain utilization type can be used.

FIG. 2 is a schematic block diagram showing the arrangement of the printing apparatus according to this embodiment. As shown in FIG.
The printing apparatus according to the embodiment reads out the incidental information F from the image data S0 ′ obtained by the apparatus shown in FIG.
The incidental information F and the image data S in which the incidental information F is separated
0 "and the additional information reading means 12 and the image data S0"
Pattern embedding conversion to obtain the image data S1 '(CMYK) for printing, which is obtained by embedding the supplementary information F as a bit pattern in the image data and converting the image data S0 ″ into CMYK to have four colors of CMYK and in which the supplementary information F is embedded. Means 3
And a printing unit 4 for printing the image data S1 'on a sheet.

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

The switch 6 is used to select which of the two color conversion LUTs 1 and 2 is used to convert the pixel value of a pixel in the image data S0 ″ from RGB to CMYK. , By changing 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, color conversion L is performed.
The switch 6 is switched so that the color conversion LUT 2 is selected when UT 1 is selected and 1.

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 conversion by 1 and 2
2 (CMYK) and data S2 '(C'M'Y'K)
Have 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 CIE colorimetric values of printed colors for CMYK data. And CMYK ()
Is a conversion formula for converting RGB data into CMYK data.

Here, CMYK and C'M'Y'K '
Is a data pair calculated from the same print color reproduction characteristic description data K in the CMYK conversion LUT creating means 7 and having the same colorimetric value, that is, a condition equal color pair. Therefore, although the two data S2 and S2 'obtained by the color conversion LUTs 1 and 2 are different, the printing unit 4
The same color is perceived on the printed matter obtained by. Therefore, the pixel value corresponding to the part 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 part other than the bit pattern P is converted by the color conversion LUT1. , The data S2 ′ and the data S2 are obtained, and the image data S1 ′ is constituted by these, and the printing means 4 performs printing based on the image data S1 ′. It becomes imperceptible to the human eye.

CMYK having such a condition color matching relationship
Table 1 below shows an example of the combination of data obtained from the color reproduction characteristics in a four-color offset printing machine. The combinations shown in Table 1 were obtained so as to achieve color matching under a standard observation light source with a color temperature of 5000K, and the Lab values in Table 1 are under this light source. The combinations of CMYK data for color matching are not limited to those shown in Table 1, and various other combinations can be used.

[0031]

[Table 1]

Note that the modulation intensity of the embedded bit pattern P can be changed by specifying the modulation intensity parameter H when the LUT is created by the CMYK conversion LUT creating means 7. For example, if the data A shown in Table 1 above is used as the CMYK data and the data B is used as the C'M'Y'K 'data, the modulation intensity of the bit pattern P becomes relatively small. Therefore, by setting such a condition, the incidental information F is not easily visually recognized even if the observation light source is changed to some extent, and thus it is suitable for an application where importance is placed on invisibility. On the other hand, when the data A shown in Table 1 above is used as the CMYK data and the data C is used as the C'M'Y'K 'data, the modulation intensity of the bit pattern P becomes relatively large. Therefore, under such a condition, the embedded incidental information F cannot be visually recognized under the standard light source, but it becomes easy to detect the incidental information F under different light sources. Therefore, it is suitable for applications in which detectability is important.

When the additional information F is a multi-valued bit pattern P, that 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, the data with a large K value is selected from the condition color matching group, and if the value is small, it is proportional to it. Then, by selecting data having a small K value, it becomes possible to embed a pattern having a gradation corresponding to the bit pattern P.

Next, the operation of this embodiment will be described. FIG. 4 is a flowchart showing the processing performed in this embodiment. First, the image reading unit 1 reads the photographic original G and acquires RGB image data S0 (step S1). On the other hand, the incidental information generating means 10 generates incidental information F for deep-encrypting and embedding in the image data S0 (step S2). Then, the supplementary information F is deeply encrypted in the embedding means 11 and embedded in the image data S0, and the image data S0 'in which the supplementary information F is embedded is obtained (step S3).

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

As described above, in this embodiment, the image data S0 '(RGB) is converted into the printing image data S1'.
When converting to (CMYK), the pixel corresponding to the additional information F to be embedded is color-modulated with the pixels of other portions so as to be modulated, so that even if the printed matter is observed under a certain observation light source, the additional information portion The color of the other part and the color of the other part are perceived as the same color, but under the specific observation light source, the color of the incidental information part is perceived as a color different from the color of the other part. Become. Therefore, the embedded incidental information F cannot be visually recognized under a normal light source, but the incidental information F can be visually recognized only under a special light source, and as a result, unauthorized duplication is prevented. The information can be embedded in the printed matter so that it cannot be easily perceived.

Since the supplementary information F is embedded in the image data S0 ', when the image data S0' is reproduced, the supplementary information F appears as noise in terms of image quality.
The image quality will deteriorate. On the other hand, in the present embodiment, the incidental information F from the image data S0 '
And the additional information F is embedded in the image data S0 ″ from which the additional information F has been separated as a bit pattern.
Since the image data S1 'for printing is converted,
The incidental information F does not appear as noise, so that a high quality printed image can be obtained.

In the above embodiment, CMYK is used.
The case of performing printing with four colors of CMYGOK has been described, but the case of performing printing with six colors of CMYGOK to which orange (O) and green (G) are added is the same as above.
Can be embedded. In this case, for example, by changing the ratio of CY and G, or by changing the ratio of MY and O, the incidental information F can be embedded by color matching the conditions, but as shown in Table 1 above, K It is also possible to color-match the conditions by changing the values.

In the above embodiment, the supplementary information F is a bit pattern, and the bit pattern portion and the portion other than the bit pattern are color-matched and embedded in the image data S1 'for printing. However, the incidental information F may be inserted as a watermark in the printing paper, or the incidental information F may be printed with UV ink. In this case, the incidental information F can be visually recognized by irradiating the ultraviolet rays. Further, the supplementary information F may be printed and embedded on the metal belt,
The supplementary information F may be embedded as micro characters. Further, the supplementary information F may be embedded in the header portion of the image data S1 'for printing.

[Brief description of drawings]

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

FIG. 2 is a schematic block diagram showing the 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 showing a process performed in this embodiment.

[Explanation 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 generating means 11 Embedding means 12 Additional information reading means

Claims (12)

(57) [Claims] 1. A printing method for converting image data in which additional information is deep-encrypted by a predetermined deep encryption method and embedded and converting the embedded image data into print data to perform printing, wherein the additional information is extracted from the image data. Separation to obtain separation image data, conversion of the separation image data to the printing data, and embedding of the supplementary information in the printing data by a method different from the predetermined deep encryption method. Method. 2. The print data in which the supplementary information is embedded is obtained by modulating the data of the supplementary information portion in which the supplementary information is embedded in the print data so that the data of the other portion has substantially the same color. The printing method according to claim 1, wherein: 3. The number of color components of the print data is the image
It is larger than the number of color components of data.
The printing method described in 2. 4. The printing data is a four-color CMYK format.
Minute data, and changes at least the K data value of the four color component data
By doing so, the data of the additional information part and the other
A contract characterized by color matching with partial data
The printing method according to claim 2 or 3. 5. The supplementary information is obtained by a predetermined deep encryption method.
Image data embedded with deep encryption and embedded
A printing device for converting the data into data and printing the separated data by separating the supplementary information from the image data.
And a conversion means for converting the separated image data into the printing data.
Means and the predetermined deep encryption of the supplementary information in the print data
Equipped with embedding means to embed by a method different from the method
A printing device characterized by the above. 6. The embedding means is provided in the print data.
Data incidental information portion in which the supplementary information takes is embedded
Is modulated by making the color of the other part of the data almost the same as the condition.
This is a means to obtain printing data in which the supplementary information is embedded.
The printing apparatus according to claim 5, wherein the printing apparatus is a printing apparatus. 7. The number of color components of the print data is the image
Claims, characterized in that greater than the number of color component data
6. The printing device according to item 6. 8. The printing data comprises four colors of CMYK.
Minute data, and the embedding means includes at least K among the four color component data.
By changing the value of the data,
A method to match the data and the data of the other part with almost the same condition
Printing according to claim 6 or 7, characterized in that it is a step.
apparatus. 9. The incidental information is obtained by a predetermined deep encryption method.
Image data embedded with deep encryption and embedded
Perform printing on a computer by converting the data into a print data
Computer read recording program for
The recording medium is capable of storing the supplementary information from the image data.
Procedure for separating and obtaining separated image data, and procedure for converting the separated image data into the print data
And the additional information to the print data, the predetermined deep encryption
Have a procedure to embed by a method different from the method
A computer-readable recording medium characterized by. 10. The embedding procedure includes the printing data.
Of the supplementary information part in which the supplementary information in the
The data is modulated by color matching the data of the other parts with the same condition.
To obtain print data in which the supplementary information is embedded
10. The computer reading according to claim 9, characterized in that
Removable recording medium. 11. The number of color components of the printing data is the image
Claims characterized by being larger than the number of color components of image data
Item 10. A computer-readable recording medium according to item 10. 12. The printing data is four colors of CMYK.
Consisting of component data, The embedding procedure is at least one of the four color component data.
By changing the value of K data,
Minute data and the data of other parts are color-matched
The procedure according to claim 10 or 11, characterized in that
A computer-readable recording medium.