JP2000324326A - Picture processor and printing system and hidden pattern embedding method and storage medium recording program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To add a readable hidden pattern to any object while suppressing the deterioration of picture quality to the minimum by deciding the color of the hidden pattern according to the background color of a printed picture. SOLUTION: A host computer 1 is constituted of hardware such as a CPU, memory, and display device and software for controlling the hardware equipment. The software is divided into an operation system(OS) 3 and an application program 4 and a driver 6 operating under the control of the OS3. The driver 6 is provided with a print data generating part 7 and a hidden pattern generating part 8 and an embedment judging part 9, and the hidden pattern generating part 8 is provided with a function for embedding prescribed identification information in a printed picture, that is, a function for deciding the color of the hidden pattern according to the color of the printed picture, that is, a background into which the hidden pattern should be embedded, and for embedding the hidden pattern into the printed picture as a pattern for identification and trace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image processing apparatus, a printing system, a hidden pattern embedding method, and a storage medium on which a program is recorded. More specifically, the present invention relates to an image processing apparatus and a printing system for embedding a hidden pattern in order to prevent forgery of a piece of money such as a banknote or the like, or to illegally duplicate a work such as a book, a photograph, or a painting. And a storage medium in which a hidden pattern embedding method and a program are recorded.

[0002]

2. Description of the Related Art With the development of color image reading technology, image processing technology, and printing technology, a printed material obtained by copying from an original using an image output device such as a copying machine or a printer is an original and a copy thereof. The image quality has become so high that it is difficult to identify them at first glance. Such a high-quality image output device is used, for example, for forging banknotes, securities, gift certificates, stamps and other securities, notarized documents, official documents, private documents, etc., and for writing books, photographs, pictures, etc. When used for reproduction of goods, it is difficult to avoid a situation in which they are generally circulated in large quantities without being distinguished from genuine ones, which causes great disruption in society.

[0003] In order to prevent such abuse,
Image reading devices such as scanners are required to be able to identify originals that are not permitted to be copied or duplicated when reading originals, and it is possible to prohibit copying by using the identification results. Alternatively, it can be processed into special image information or added with special image information at the time of copying, and output, so that a copy or duplicate can be distinguished from an original.

On the other hand, in an image output device such as a copying machine or a printer, it is effective to add identification information as a "hidden pattern" so that the reproduced image can be tracked without deteriorating the image quality. is there.

Recently, there has been an increasing number of occasions in which literary works such as paintings and photographs are distributed as electronic data. However, electronic data can be easily copied and can be copied in large quantities by a printer or the like. It is. For this reason, in order to clarify the location of the copyright and prevent illegal duplication, when printing electronic data on a work such as a painting with a printer, the identification information such as the name of the copyright "
Embedding technology is also being studied.

For example, some image processing apparatuses have been proposed which record specific information by giving a specific pattern as a “hidden pattern” so that the apparatus that reproduced the image can be identified and tracked in the image. (For example, JP-A-4-294682, JP-A-5-1)
No. 4682). In addition, the density of the "hidden pattern" is changed according to the area of the input image, so that the output result of securities such as banknotes and stamps can be more reliably tracked, and other images can be traced. With respect to the above, an apparatus has been proposed to prevent image quality deterioration by providing a pattern that is less noticeable (Japanese Patent Laid-Open No. 7-11581).
No.).

[0007]

Generally, such a "hidden pattern" is printed on a printed matter output from a printer or the like.
Is disadvantageous in that the image quality of the printed matter is deteriorated. Conventionally, in order to cope with this problem, a method has been adopted in which a "hidden pattern" is added to a printed material using a color that is difficult for human eyes to recognize. For example, in the above-mentioned Japanese Patent Application Laid-Open No. 4-294682, in a printer using four color elements of magenta (M), cyan (C), yellow (Y) and black (K), yellow (Y) is always used. A technique of adding a “hidden pattern” using only the color elements of the above has been disclosed. The reason why the yellow (Y) color element is always used is that yellow (Y) is the color most difficult to be recognized by human eyes among the above four colors.

However, when a "hidden pattern" is always added using only the yellow (Y) color element, the image quality is significantly degraded or the hidden pattern is read depending on the contents of the printed matter. There is a problem that it becomes difficult. For example, when the print object is a text document on a white background, it is relatively easy to read the “hidden pattern” formed in yellow (Y), and the image quality is hardly degraded.

On the other hand, the print objects are M,
In the case of an image such as a photographic image that makes extensive use of C, Y, or K, the “hidden pattern” added only with the Y color element has a large contrast difference from the background, and may degrade the image. . Conversely, there is also a case where it is buried in the background, making it extremely difficult to read. In particular, such a problem occurs in the case of a print object such as a banknote, a securities, or various literary works that requires reading of a “hidden pattern”.

On the other hand, if a "hidden pattern" is always added using a specific color element which is easy to identify to the human eye in order to facilitate reading, a light background such as a white text document can be obtained. When a print object is printed, the "hidden pattern" becomes too conspicuous, and the image quality deteriorates.

The present invention has been made based on the recognition of such a problem. That is, the object is to provide an image processing apparatus, a printing system, and a hidden pattern embedding method that can add a “hidden pattern” capable of reading while minimizing the deterioration of the image quality to any object. An object of the present invention is to provide a storage medium storing a method and a program.

[0012]

In order to achieve the above object, an image processing apparatus according to the present invention is provided with a color print data input to a printer capable of printing data using a plurality of color elements by inputting data relating to a color image. An image processing apparatus that outputs a hidden pattern generation unit that embeds predetermined identification information as a hidden pattern in a print image included in the color print data, wherein the hidden pattern generation unit includes a background of the print image. The color of the hidden pattern is determined according to the color.

[0013] By determining the color of the hidden pattern according to the background color in this way, it is possible to embed the hidden pattern without deteriorating the image quality and to reliably read the hidden pattern.

Here, the hidden pattern generating means sets each of the plurality of color elements used by the printer and a combination of at least two or more of the plurality of color elements as a color candidate, and Determining the color of the pattern as one of the color candidates,
An optimal one of the color elements used by the printer can be appropriately selected to form a hidden pattern dot.

Further, the hidden pattern generating means determines a color having the closest lightness to the background color of the print image among the color candidates as a color of the hidden pattern. Is less noticeable to human eyes, and reading can be performed reliably and easily.

Further, the hidden pattern generating means determines the background color of the print image in accordance with the number of dots of the plurality of color elements, and the print pattern stored in a buffer memory of a printer driver. It can be easily processed based on the image data.

The hidden pattern generating means may include means for dividing the print image into a plurality of divided areas, and means for determining a background color of the divided area in which the hidden pattern is to be embedded, of the plurality of divided areas. Means for determining the color of the hidden pattern in accordance with the determined background color, wherein the hidden pattern can be embedded using an optimum color for each divided area.

Alternatively, the hidden pattern generating means divides an area of the print image in which the hidden pattern is to be embedded into a plurality of sampling areas, and determines a background color for each of the plurality of sampling areas. Means, for each of the plurality of sampling regions, means for determining the color of the hidden pattern corresponding to the determined background color, further divide the embedded portion into each Hidden patterns can be embedded using optimal colors.

Alternatively, the hidden pattern generation device may include means for analyzing a color distribution in at least a part of the print image, and means for determining an area in which the hidden pattern is to be embedded based on the analyzed color distribution. Means for determining a background color of an area where the hidden pattern is to be embedded, and means for determining the color of the hidden pattern according to the determined background color. A hidden place can be embedded by selecting a suitable place and using an optimum color.

On the other hand, the printing system of the present invention is a printing system for inputting data relating to a color image and outputting it as a print image using color elements of a plurality of colors, wherein predetermined identification information is hidden in the print image. A hidden pattern generating unit that embeds the hidden pattern as a pattern, wherein the hidden pattern generating unit determines the color of the hidden pattern according to the background color of the print image. By determining the color, it is possible to embed the hidden pattern while suppressing the deterioration of the image quality, and to surely read the hidden pattern.

On the other hand, the hidden pattern embedding method of the present invention is a hidden pattern embedding method for embedding predetermined identification information as a hidden pattern in a color image, wherein the color of the hidden pattern is changed according to the background color of the color image. It is characterized in that the hidden pattern is embedded while the deterioration of the image quality is suppressed, and the reading thereof can be surely performed.

On the other hand, the recording medium of the present invention is a recording medium in which a program for inputting data relating to a color image and outputting color print data to a printer capable of printing using a plurality of color elements is provided. The program is
A hidden pattern generation step of embedding predetermined identification information as a hidden pattern in a print image included in the color print data, wherein the hidden pattern generation step includes:
The color of the hidden pattern is determined according to the background color of the print image. The hidden pattern can be embedded while suppressing the deterioration of the image quality, and the reading thereof can be performed reliably.

Here, the recording medium includes, for example, various memories such as a RAM and a ROM in addition to a hard disk (HD), a DVD-RAM, a DVD-ROM, a flexible disk (FD) and a CD-ROM. .

The programs to be recorded on these media are encrypted, modulated, or compressed, and stored in a recording medium via a wired or wireless line such as an intranet or the Internet. You may distribute it.

[0025]

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

(First Embodiment) In this embodiment, a print image is divided into a plurality of divided areas, and a "hidden pattern" is formed for each of the divided areas using a color selected based on the background color. Embed.

FIG. 1 is a block diagram illustrating a schematic configuration of a printing system according to the present invention. That is, the printing system of FIG. 1 includes a host computer 1 and a printer 2.

The host computer 1 includes hardware such as a CPU, a memory, a display device, a keyboard, a mouse, and the like, and software for controlling these hardware devices. The software is divided into an operating system (hereinafter, referred to as an OS) 3, an application program 4 operating under the management of the OS 3, and a driver (print information generating device) 6.

OS3 is a GDI (Graphics Device Inte
rface) module 5 and an interface unit 10. The GDI module 5 analyzes the application data output from the application program 4 such as a word processor and generates print data.
The interface unit 10 transmits the data output from the GDI module 5 to the printer 2 under the control of the driver 6, receives the status information sent from the printer 2, and supplies the status information to the driver 6.

The driver 6 includes a print data generation unit 7, a hidden pattern generation unit 8, and an embedding determination unit 9.
The print data generation unit 7 receives the data output from the GDI module 5 and generates and outputs print data (for example, bit image data) unique to the printer 2 and print data such as control commands.

The hidden pattern generator 8 has a function of embedding predetermined identification information in a print image according to the present invention. That is, as described later in detail, the function of determining the color of the hidden pattern in accordance with the print image in which the hidden pattern is to be embedded, that is, the color of the background, and embedding the hidden pattern in the print image as a pattern for identification and tracking. Have.

The embedding determination section 9 determines whether or not to embed identification information based on data included in or attached to the application data output from the application program 4.

On the other hand, based on the print data input from the driver 6 via the interface unit 10, the printer 2 makes the print data visible on various recording media such as paper using a plurality of color elements. Output function. Specific examples thereof include various types of printers such as an ink jet printer that ejects ink in a dot shape, a laser printer using an electrophotographic system, a thermal transfer printer, and a sublimation printer using a thermal sublimation type ink. Can be used.

FIG. 1 shows an example of a configuration using an ink jet printer. That is, the printer 2 includes an interface unit 11 that transmits and receives print information to and from the driver 6, an interpreter 12 that analyzes the contents of the print data sent from the driver 6, and a printer based on the analysis result by the interpreter 12. An image generation unit 14 that generates a print image; and a printer engine 15 that performs drive control of a print head and a paper feed mechanism (not shown) to execute printing.
And a panel unit 16 for displaying an operation state of the printer 2 and the like.
And a status management unit 17 for controlling the state of the printer 2
A memory management unit 18 for controlling a memory (not shown) for temporarily storing a print image, and a control unit 19 for controlling each unit in the printer 2.

FIG. 2 is a block diagram illustrating the configuration of the print data generator 7 provided in the driver 6 when an ink jet printer is used. The print data generation unit 7 includes a rasterizer 7A that converts application data output from the GDI module 5 into image data in dot units, and a rasterizer 7A according to the ink color and color development characteristics used by the printer for the image data in dot units. A color correction processing unit 7B for performing color correction, a color correction table 7C referred to by the color correction processing unit 7B, and the density in a certain area expressed by the presence or absence of ink in dot units from the image data after color correction. Processing unit 7D that performs a binarization process
And an interlace processing unit 7E for rearranging the image data in association with the print nozzles.

Next, the processing performed by the hidden pattern generator 8 provided in the driver 6 will be described in detail.

FIG. 3 is a flowchart conceptually illustrating a process performed by the hidden pattern generation unit 8. The hidden pattern generation unit 8 first determines a divided area in step S11. Subsequently, step S1
In step 2, the color of the "hidden pattern", that is, the background color is determined.

Then, a "hidden pattern" is embedded in step S13 using the determined background color. Further, in step S14, it is determined whether to move to the next divided area. When moving to the next divided area (S14: YE
S) returns to step S12 for a new divided area and repeats a series of processing.

Hereinafter, steps S11 to S13 will be described in detail.

FIG. 4 is a conceptual diagram showing an example of "determination of a divided area" performed in step S11. That is, FIG. 3 shows a state in which the print image is divided into a plurality of rectangular divided regions B. As a print image to be divided, for example, an image stored in a buffer (not shown) provided at a stage subsequent to the halftone processing unit 7D of the print data generation unit 7 of the driver 6 can be used. In FIG. 4, the contents of the print image are not shown for simplicity of explanation.

As described later in detail, these divided areas B
A predetermined pattern such as, for example, "ABC" is embedded as a "hidden pattern". This pattern can include identification information for preventing forgery, identification information regarding the location of the copyright, and the like. These identifiers are
It may be stored in the hidden pattern generation unit 8 in advance. For example, when the hidden pattern generation unit 8 is provided in the driver 6 as illustrated in FIG. 1, information about the printer model, the type and version of the driver, and the like are stored in the hidden pattern generation unit 8. Can be.

On the other hand, these identification information may be input from the OS 3 or the printer 2 as needed. For example, identification information on the date of manufacture, lot number, format, etc. of the printer can be input from the printer and embedded as a “hidden pattern”. Further, from the OS 3, identification information on the type and version of the OS, the printing date and time, and identification information on a copyright that can be input along with the image data can be input and embedded as a “hidden pattern”.

Step S11 can be executed, for example, in any subsequent stage of the rasterizer 7A, the color correction processing unit 7B, and the halftone processing unit 7D of the print image generation unit 7 provided in the driver 6 illustrated in FIG. . That is, by inputting image data output from any of these processing units, a predetermined divided region can be determined as appropriate.

On the other hand, the divided area B may be provided in the form of a network over the entire print image, or may be provided only on a part of the print image. The size of the divided area B is, for example, 1
It can be about 0 millimeter. However, the shape and dimensions can be appropriately changed according to the paper size, the type of print object (for example, text data or bit image data), and the like. Further, it is not necessary that all the divided areas B have the same shape and dimensions on one print image. For example, the size of the divided area B may be increased in the peripheral portion of the printed matter, and reduced in the vicinity of the center of the printed matter. Alternatively, the reverse may be performed.

In the example shown in FIG. 4, "hidden patterns" are not embedded in all the divided regions, but "hidden patterns" are embedded in the divided regions spaced in a zigzag pattern. By doing so, an effect is obtained that the hidden pattern is less noticeable. However, a hidden pattern may be embedded in all the divided areas.

Referring back to FIG. 3, after the image to be printed is divided into predetermined divided areas, the color of the hidden pattern embedded in each divided area B is determined in step S12. You.

FIG. 5 is a flowchart showing the details of the processing in step S12. That is, first, in step S12A, the "background color"
To determine. Next, in step S12B, the color of the hidden pattern is determined based on the background color.

The determination of the background color in step S12A can be made based on the ratio of the colors used in the divided area. As an example, a case where printing is performed using four color elements of yellow (Y), cyan (C), magenta (M), and black (K) will be described below. These color elements correspond to, for example, ink colors of an inkjet printer.

The background color of a certain divided area B can be obtained, for example, by averaging the area occupied by the four colors used in the divided area B and other parameters. In this case, an intermediate color in which the above four colors are allocated at a predetermined ratio is obtained as the "background color".

Further, based on three elements of “color”, that is, parameters such as lightness, hue, and saturation,
The “background color” of the divided area may be analyzed.

FIG. 6 shows that hue, saturation, and lightness are each represented by x.
FIG. 4 is a conceptual diagram illustrating a three-dimensional distribution of colors for an axis, a y-axis, and a z-axis.

Conceptually, Y, C, M, and their combined colors can be plotted at positions as shown in FIG. Pure black (K) has only “lightness” and neither “hue” nor “saturation”, but is plotted in FIG. 6 for convenience only based on “lightness”.

In FIG. 6, a symbol B indicates a certain divided area B.
Is an example of the distribution of colors used in. That is, the distribution of colors used in the divided area B is represented by hue,
It can be represented three-dimensionally in this way using saturation and lightness. The symbol W represents the background color of the divided area B (or the center of gravity of the distribution). As a method of this determination, for example, as described above, there is a method of taking a weighted average based on the area occupied by each color in the divided region B.

When the background color W of the divided area B is determined in this way, among the Y, C, M, and K used as color elements and a combination thereof, a color close to W is set as the color of the “hidden pattern”. select. Parameters to be considered when selecting a color close to W include hue, saturation, and lightness, or a combination thereof.

For example, among Y, C, M, K, and combinations thereof, there is a method of selecting a color having the closest “hue” as compared with the background color W as a “hidden pattern” color. In this case, the “hidden pattern” can be embedded with a color similar to the average hue of the print image (background) of the divided area B. Therefore, it is particularly effective when it is desired to prevent the print quality from deteriorating due to hue shift.

Further, among Y, C, M, K and a combination thereof, a color having the closest “saturation” as compared with the background color W may be selected. This method is particularly effective when it is desired to prevent the deterioration of the print image quality due to the difference in saturation between the print image and the “hidden pattern”.

Further, among Y, C, M, K and combinations thereof, a color having the closest “brightness” as compared with the background color W may be selected. The human eye has a characteristic that, among the three elements of color, "lightness" is more sensitive than "hue" or "saturation". Therefore, based on “brightness”, “hidden patterns” are advantageous in that they are extremely inconspicuous.

Further, after multiplying each of the hue, saturation and lightness by a predetermined coefficient, the plot is three-dimensionally plotted as shown in FIG. ,
There is also a method of selecting the color at the shortest distance among C, M, K and a combination thereof as the color of the “hidden pattern”. In this case, all three elements of hue, saturation, and lightness can be appropriately weighted and taken into consideration. Therefore, it is possible to secure the readability to some extent while preventing the print quality from deteriorating.

In the following description, as one specific example,
First, a method of roughly classifying the colors of the “hidden pattern” based on the “brightness” and further determining the color of the “hidden pattern” in consideration of the “hue” and the “saturation” will be described.

Taking an ink jet printer as an example,
The print data generated by the print data generation unit 7 of the driver 6 in FIG. 1 is stored in a palette for each color. That is, the print data is stored in four separate buffer memories of yellow (Y), cyan (C), magenta (M), and black (K). These buffer memories (not shown) are provided, for example, after the halftone processing unit 7D shown in FIG. Therefore, it is possible to count the number of dots belonging to a predetermined divided area in the buffer memory of each color by a simple process.

The number of yellow (Y) dots counted in a certain divided area is y, the number of cyan (C) dots is c, the number of magenta (M) dots is m, and the number of black (K) dots is Is k. Then, the average darkness (opposite of lightness) D of the divided area is obtained by the following equation.

D = y + αc + βm + γk (1) where α is the relative darkness of the C dot with respect to the Y dot, β is the relative darkness of the M dot with respect to the Y dot, γ
Is a coefficient indicating the relative darkness of the K dot with respect to the Y dot.

In step S12B, the color of the hidden pattern can be determined based on the "darkness D" obtained by equation (1). Specifically, among the color elements of the printer, a color element having “darkness” closest to “darkness D” of the divided area is used.

The color of the hidden pattern selected in step S12B is not limited to one of the color elements of the printer, but may be a combination of these colors. For example, if there are four color elements of yellow (Y), cyan (C), magenta (M), and black (K), (Y
+ C), (Y + M) and (C + M) can also be used.

An example of a process for determining a color that can be made in step S12B in consideration of such a combination color is as follows. That is, the following four indices are defined as “darkness indices”.

D1: D when the entire divided area is printed with Y, and D when the entire divided area is printed with C or M
D2: D when the entire divided area is printed with C or M
D when the entire divided area is printed with Y + C or Y + M, and D when the entire divided area is printed with Y + C or Y + M, and C + M prints the entire divided area. D when
D and K when the entire divided area is printed with a value d4: C + M located in the middle between
When d1 to d4 are defined as described above, the relationship between the darkness of each color is as follows.

Y <d1 <C or MC or M <d2 <(Y + C) or (Y + M) (Y + C) or (Y + M) <d3 <(C + M) (C + M) <d4 <K Each of d1 to d4 Can be appropriately adjusted within the range defined above. That is,
While maintaining the relationship d1 <d2 <d3 <d4, it is possible to select an optimal value according to the characteristics of the printing mechanism.

The d1 to d4 defined in this way are compared with the “darkness D” obtained from the equation (1) in each divided area. Then, the color of the hidden pattern in the divided area can be determined as follows.

When D <d1: The color of the hidden pattern is Y.

When d1 ≦ D <d2: If c> m, C is set. Otherwise, it is M.

When d2 ≦ D <d3: (y + c)> (y
+ M), then (Y + C).

Otherwise, it is (Y + M).

When d3.ltoreq.D <d4: (C + M).

When d4 ≦ D: K is set.

This corresponds to dividing the three-dimensional space shown in FIG. 6 into five spaces in the horizontal direction by a plane passing through each of d1 to d4 on the lightness axis.

FIG. 7 is a conceptual diagram two-dimensionally displayed using only the hue axis (x-axis) and the brightness axis (z-axis) for simplicity. d1 to d4 can be plotted along the lightness axis as shown. Also, the colors of Y, C, M, K and combinations thereof can be plotted as shown.

In FIG. 7, reference numeral B1 exemplifies the distribution of colors used in a certain divided area B1. The point W1 in this distribution is the average value (or the center of gravity) of the background color, and the point projected on the lightness axis is “darkness D1” obtained from the equation (1) for the divided area B1. is there. In the case shown in the figure, the “darkness D1” of the divided area B1 is between d1 and d2. That is,
This corresponds to the above-mentioned “d1 ≦ D <d2”. Therefore, C or M can be selected as the color of the hidden pattern. On the other hand, since the hue of W1 is close to M, M is selected as the color of the hidden pattern. This is because c in equation (1)
<M, and also considers “hue” and “saturation”.

Further, in FIG. 7, reference numeral B2 exemplifies the distribution of colors used in another divided area B2. The center of gravity W2 of the divided area B2 is C and (C
+ Y), and (C +
Close to Y). However, here, the determination is made based on the difference in brightness. That is, the center of gravity W2 of the background color of the divided region B2 is between the lightness axes d1 and d2. The hue of W2 is M
Than C. Therefore, C is selected as the color of the “hidden pattern” of the divided area B2.

In the specific example described above, in each of the divided areas, first, the color of the “hidden pattern” is roughly determined based on the “brightness”. The human eye has a characteristic of being more sensitive to “brightness” than “hue” or “saturation” among the three elements of color. Therefore,
According to the specific example described above, by selecting the color of the “hidden pattern” using “brightness” as the first criterion, embedding the “hidden pattern” that is not so noticeable to human eyes and easy to read. Can be. Furthermore, by reading the printed matter printed by this method using a scanner or the like and examining the distribution of “hue” or “saturation” on the read data, the “hidden pattern” embedded in the printed matter can be extremely easily and Can be read accurately.

Further, in the above-described specific example, after roughly classifying by "brightness" and further considering "hue" and "saturation", the "hidden pattern" Can be embedded.

Returning to FIG. 3, once the divided area is determined in step S11 and the dot color is determined in step S12, the “hidden pattern” is embedded in the divided area in step S13. This processing is performed, for example, in the case of an ink jet printer, in the final stage of the print data generation unit 7 of the driver 6, Y, C, M and K
Is executed by adding data corresponding to the “hidden pattern” to the corresponding one of the buffer memories of the respective colors.

Next, in step S14, it is determined whether or not to move to the next divided area. If there is a next divided area, the process returns to step S12, and the color of the “hidden pattern” is determined for the new divided area.

According to the present embodiment, as described above, the print image is divided into a plurality of divided areas, and the color of the “hidden pattern” is determined for each of the divided areas in relation to the background color. For example, referring to FIG. 4, for example, a “hidden pattern” is embedded using C in the divided area B1, an “hidden pattern” is embedded using Y in the divided area B2, and (Y + M) is embedded in the divided area B3. ) To embed the “hidden pattern”. As described above, by determining the color of the “hidden pattern” for each divided area, it is possible to flexibly select a color with less discomfort according to the content of the print image, and to suppress deterioration of image quality extremely effectively. it can.

Further, in the specific example illustrated in FIG. 7, by determining the color of the “hidden pattern” using “brightness” as a first criterion, it is possible to use a color that is less noticeable to human eyes.

The specific examples described above are merely examples, and other examples include “hue”, “saturation”, and “brightness”.
The color of the “hidden pattern” may be determined based only on the color. First, the color may be roughly selected based on “hue” or “saturation”, and the color may be determined in consideration of the remaining elements.

(Second Embodiment) In the present embodiment, a print image is divided into a plurality of divided areas, and each divided area is further divided into a plurality of sampling areas, and the background color of each sampling area is set as a background color. The “hidden pattern” is embedded using the color selected based on the color. That is, even in one divided region, the color of the “hidden pattern” can change for each part.

In this embodiment, the processing can be performed according to the same flow as that illustrated in FIG. That is, in step S11, the print image is divided into a plurality of divided areas. This situation is, for example, as illustrated in FIG.

Next, in step S12, the color of the hidden pattern is determined. However, the processing content of this step is different.

FIG. 8 shows step S1 in the present embodiment.
6 is a flowchart illustrating details of a second example. First, in step S12D, the divided area is further divided into a plurality of sampling areas.

FIG. 9 is a conceptual diagram of a print image for explaining this step. This figure shows a state in which a pattern “ABC” is embedded as a hidden pattern in the divided area B of the printed matter. In FIG. 9, the contents of the print image are not shown for simplicity of description.

In step S12D, the divided area B
Is further divided into a plurality of sampling areas b1 to bn. The shape and dimensions of this sampling area are
Can be appropriately determined in consideration of the shape and size of the image, the nature of the print image, the type of the hidden pattern, the embedding position, and the like. For example, the sampling area may be a minute area such as several adjacent dots on a print image.

Next, in step S12E, for each sampling area, the "background color"
To determine. This process can be performed similarly as described above with respect to step S12A. That is,
The determination of the background color can be made based on the ratio of the colors used in the sampling area.

Next, in step S12F, the color of the "hidden pattern" is determined for each sampling area.
This process can also be performed as described above with respect to step S12B. That is, for each sampling area, a color close to the “background color” is selected as a “hidden pattern” color while appropriately considering “hue”, “saturation”, and “brightness”. Here, as described above, if a color having a similar “brightness” is selected, an effect that the “hidden pattern” is less noticeable to human eyes can be obtained.

Next, in step S12G, it is determined whether or not to move to the next sampling area. When moving to the next sampling area, the process returns to step S12F, and the processing is repeated for a new sampling area.

If the process does not proceed to the next sampling area, the process proceeds to step S13 in FIG. 3, and the "hidden pattern" is embedded using the color selected for each sampling area. However, instead of embedding the “hidden pattern” here, FIG.
After the color is determined in step S12F, the portion of the “hidden pattern” corresponding to the sampling area may be embedded.

Next, the process proceeds to step S14 in FIG. 3, and it is determined whether or not to move to the next divided region. If there is a next divided region, the process returns to step S12 to repeat the processing. In step S14, only the divided area in which the “hidden pattern” is to be embedded may be determined. For example, FIG.
As illustrated in FIG. 9 and FIG. 9, when embedding a “hidden pattern” in a houndstooth check pattern, the processes of S12 to S13 may be performed only on the divided area to be embedded.

According to the present embodiment described above, the divided area is further divided into a plurality of sampling areas, and the "background color"
And embed the “hidden pattern” by selecting a color corresponding to each “background color”. For example, in the example shown in FIG. 9, the color of the “hidden pattern” is uniquely determined in each of the sampling regions b1 to bn.

Therefore, a "hidden pattern" such as "ABC" may be embedded in a different color for each part of the pattern. As a result, it is possible to flexibly adjust the color of the “hidden pattern” according to the color distribution in the divided area, to make the “hidden pattern” less noticeable, and to suppress deterioration in image quality.

(Third Embodiment) In the present embodiment, no particular divided area is provided, and only the area near the part where the "embedding pattern" on the print image is to be embedded is sampled and its background color is analyzed. Then, the color of the “embedded pattern” is selected based on the analysis result.

This embodiment can also be executed by the hidden pattern generator 8 shown in FIG. 1, for example.

FIG. 10 is a flowchart showing the processing performed by the hidden pattern generator 8 in this embodiment.

First, in step S21, a sampling area is determined. That is, a print image is input, and an area near the position where the “hidden pattern” is to be embedded is set as a sampling area. Here, as the target print image, for example, an image stored in a buffer (not shown) provided after the halftone processing unit 7D of the print data generation unit 7 of the driver 6 can be used. . FIG. 11 is a conceptual diagram illustrating a part of a print image. FIG. 3 illustrates an example in which a character “AB” is embedded as a “hidden pattern” in a print image. In the figure, the content of the print image is
Omitted for simplicity of explanation. In the example of FIG. 11, in step S21, the sampling area b1, the sampling area b1,
are determined.

If the position and shape of the “hidden pattern” are known in advance, the positions and dimensions of these sampling areas can be determined in advance. Further, the position and size of the sampling area may be changed as appropriate according to the content of the print image. Further, information on the hidden pattern may be input from the printer 2 or the OS 3 as needed, and the sampling area may be determined according to the pattern.

Next, in step S22, the background color of each sampling area is determined.

Further, in step S23, the color of the "hidden pattern" is determined for each sampling area. That is, an optimal color is appropriately determined according to the background color of the sampling area.

As the processes performed in steps S22 and S23, the various methods described above with respect to the first embodiment can be appropriately selected and used.

Next, in step S24, a "hidden pattern" is embedded. For example, for the sampling area b1 shown in FIG. 11, the tip of “A” of the “hidden pattern” is embedded in the print image using a color corresponding to the background color.

Next, in step S25, it is determined whether or not to proceed to the next sampling area. If the process proceeds to the next sampling area, the process returns to step S22 and the process is repeated.

According to the present embodiment, as described above, it is possible to use a color in consideration of the background color around each “hidden pattern”. For example, in the example of FIG. 11, the background color is different for each of the sampling areas b1, b2, and b3, and as a result, the color of the hidden pattern may be different. That is, the hidden pattern “A” may be embedded in a different color for each part. As a result, the color of the "hidden pattern" is flexibly adjusted according to the color distribution of the print image where the "hidden pattern" is to be embedded, making the "hidden pattern" more inconspicuous and suppressing image quality degradation can do.

(Fourth Embodiment) In this embodiment, first, the color distribution in the whole or a part of the print image is analyzed. Then, the print image is divided based on the result of the analysis, a color is selected, and a “hidden pattern” is embedded.
According to this method, for example, it is possible to search for a portion having a small change in color and embed a “hidden pattern” therein.

This embodiment can also be executed by the hidden pattern generator 8 shown in FIG. 1, for example.

FIG. 12 is a flowchart showing the processing performed by the hidden pattern generator 8 in this embodiment.

First, in step S13, the distribution of colors on the print image is analyzed. That is, a print image is input, and what colors and how are distributed on the print image is analyzed. This analysis may be performed for the entire print image, or may be performed for only a part of the print image.
As a print image to be analyzed, for example, an image stored in a buffer (not shown) provided at a stage subsequent to the halftone processing unit 7D of the print data generation unit 7 of the driver 6 can be used.

Next, in step S32, the hidden pattern embedding position is determined.

For example, an area where the color distribution changes slowly and is relatively evenly distributed can be set as the “hidden pattern” embedding position. In this case, the reading of the “hidden pattern” is often facilitated.

Conversely, a region where the color distribution is steep and unevenly distributed may be used as the “hidden pattern” embedding position. By doing so, the “hidden pattern” becomes less conspicuous, and image quality is less likely to deteriorate.

Next, in step S33, a "hidden pattern" is embedded in the print image. Specifically, for example,
The hidden pattern data is added to a buffer memory (not shown) at the subsequent stage of the halftone processing unit 7D of the print data generation unit 7. At this time, it is necessary to determine the color of the “hidden pattern”, but it can be determined according to the color of the background at the embedding position. Specifically, it can be determined by the various methods described in the first embodiment.

Next, in step S34, it is determined whether or not to continue embedding in the analyzed print image. If the embedding is to be continued, step S
Returning to step S32, the process is repeated.

If the embedding of the analyzed print image is no longer continued, the flow advances to step S35 to determine whether or not to proceed to the next portion of the print image. That is, when the analysis is performed for each portion of the print image, the process proceeds to the next portion, and returns to step S31 to repeat the process.

FIG. 13 is a conceptual diagram showing an example of a print image. In this specific example, a mountain hut having a red roof 82 is erected on a green meadow 81 and has a blue sky 83 and white clouds 84.

Further, a town 85 where various buildings are densely located is far from the grassland 81.

When such a printed image is analyzed, the grassland 8
In part 1, a relatively uniform distribution with a high green component is obtained. In the roof 82, red is relatively uniformly distributed. In the sky 83, blue is relatively uniformly distributed, and in the cloud 84, white is relatively uniformly distributed. On the other hand, in the town 85, various colors are finely and densely distributed and unevenly distributed.

In the example of FIG. 13, the grassland 81, the roof 82, the sky 83, the clouds 84, etc. have a relatively uniform color distribution. Therefore, the “hidden pattern” is an area where reading is relatively easy. On the other hand, in the town 85, the “hidden pattern” can be said to be a region that is not conspicuous because the color distribution is uneven.

For example, in the grassland 81, a flap (Y + C)
Can be used to embed “ABC” as a “hidden pattern”. Further, “ABC” can be embedded in the portion of the red roof 82 using, for example, M. Also,
Using C for the sky 83 and Y for the cloud 84, "AB
C "can be embedded.

On the other hand, in the part of the town 85, the color of the “hidden pattern” may be set to one based on the background color obtained by sampling and averaging the whole part, or according to the color distribution of the town 85. "ABC" while switching multiple colors
Can be embedded. That is, as described in the third embodiment, the surrounding background color may be sampled for each "ABC" portion, and a color corresponding to the background color may be used.

The embodiment of the invention has been described with reference to the examples. However, the present invention is not limited to these specific examples.

For example, in each of the specific examples described above,
As the “hidden pattern”, an example of an “additional pattern” in which a pattern such as “ABC” is added in a dot shape and embedded is provided. However, the present invention is not limited to this. Another example of the “hidden pattern” is a “change pattern” that locally changes a part of the print image rather than adding a dot to the print image. That is, a “change pattern” can be formed by “shifting” the hue, saturation, or brightness of a part of the original image according to the background color.

The size of the elements constituting such a “change pattern” may be in units of pixels, or may be a region composed of a plurality of pixels.

FIG. 14 is a conceptual diagram illustrating elements constituting a “change pattern”. That is, in the example of FIG.
The element of the “change pattern” is a “patch” of 4 × 4 pixels. Each patch 51 is constituted by 16 pixels 52. The patch 51 is incorporated as a part of the pixels constituting the original image as shown in FIG. Then, by appropriately arranging such “patches” in the original image, a “change pattern” can be configured. The arrangement pattern is not limited to the alphabetic pattern such as “ABC” shown in the above-described specific example, and may include any other characters, symbols, and figures. For example, in the example shown in FIG. 15, the image is divided into a plurality of tiles 53, and a patch 51 is embedded for each tile 53 so as to represent a specific pattern corresponding to the identification information.

Also, in such a “change pattern”, the patch 5 is selected in accordance with the background color of the print image, that is, the color that the portion of the patch 51 and its surrounding portion should originally have.
One average color is determined. Specifically, the average color of the patch 51 can be determined based on any of the first to fourth embodiments. For example, if each pixel 52 is formed using a color having a different hue or saturation and a small change in lightness as compared with the background color, it is possible to prevent deterioration in image quality. That is, the embedded patch 51 becomes an integral part of the printed image, and it is almost difficult to identify it with the naked eye.

When the patch 51 is composed of a plurality of pixels, it is not necessary that all the pixels have the same color. That is, the average value of the entire patch may show a predetermined “deviation” with respect to the background color of the print image. Therefore, even when a plurality of pixels forming a patch have two or more different colors, the average brightness of the entire patch is almost the same as the background color, and if the hue or the brightness is different, the image quality is deteriorated. It is possible to embed hidden patterns while suppressing them.

As described above, by appropriately changing the colors of a plurality of pixels constituting the patch, it is possible to precisely adjust the average value of the colors of the entire patch. As a result, it becomes possible to make the average brightness of the entire patch very close to the background color, and to "shift" the hue or saturation by a predetermined amount. Therefore, it is possible to more effectively suppress the deterioration of the image quality.

[0133] In this manner, the "change pattern" is cleverly used.
Even when embedded, a "hidden pattern" can be reliably read by scanning the print image at a resolution of at least a patch unit (for example, 360 dpi) and then performing a search process on the image data as the scan result. Can be done.

As described briefly above, as the “hidden pattern” that can be used in the present invention, a “change pattern” can be applied in addition to the “additional pattern” described in each specific example.

On the other hand, in each of the specific examples described above, the case where the hidden pattern generation unit 8 is provided inside the driver 6 has been exemplified. However, besides this, for example, the hidden pattern generation unit 8
To the GDI module 5, or from the driver to the printer engine.

In the above-described specific example, an ink jet printer has been illustrated. However, the present invention can be similarly applied to various printers such as a laser printer and a thermal sublimation printer to obtain similar effects. Can be obtained. Furthermore, it is not limited to a printer dedicated machine,
A multifunction peripheral having other functions such as a copying machine and a facsimile machine may be used.

In addition, those skilled in the art can make various additions and changes within the scope of the present invention disclosed in this specification.

[0138]

The present invention is embodied in the form described above, and has the following effects.

First, according to the present invention, by determining and embedding the color of the “hidden pattern” in relation to the background color of the print image, it is possible to extremely effectively suppress the deterioration of the image quality.

For example, if the color having the closest “hue” as compared with the background color W is selected as the “hidden pattern” color, it is possible to effectively prevent the deterioration of the print quality due to the hue shift.

Further, by selecting a color having the closest “saturation” as compared with the background color W, it is possible to effectively prevent the deterioration of the print quality due to the difference in the saturation.

The human eye is more sensitive to “brightness” than “hue” or “saturation” among the three elements of color, and therefore, determines colors based on “brightness”. if,
The “hidden pattern” is advantageous in that it is extremely inconspicuous. Furthermore, the printed matter printed by this method is read by a scanner or the like to examine the distribution of “hue” or “saturation”, so that the “hidden pattern” embedded in the printed matter can be read very easily and accurately. It is also advantageous in that it can be used.

Further, the background color is obtained by multiplying each of the hue, saturation and lightness by a predetermined coefficient, and the color closest to this background color is selected as the color of the “hidden pattern”, so that the hue, the saturation All three factors of brightness and lightness can be appropriately weighted and taken into consideration, while preventing deterioration of print image quality.
Readability can also be ensured.

If the print image is divided into a plurality of sampling areas and the "background color" is analyzed, and a color corresponding to each "background color" is selected and the "hidden pattern" is embedded,
The color of the “hidden pattern” can be flexibly adjusted according to the color distribution of the print image, making the “hidden pattern” less noticeable and suppressing deterioration in image quality.

As described in detail above, according to the present invention, it is possible to embed identification information for preventing forgery or protecting copyrights in a printed matter while suppressing deterioration in image quality, and the industrial advantage is great.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a printing system according to the present invention.

FIG. 2 is a block diagram illustrating the configuration of a print data generation unit provided in a driver when an inkjet printer is used.

FIG. 3 is a flowchart conceptually illustrating a process performed by a hidden pattern generation unit 8;

FIG. 4 is a conceptual diagram illustrating an example of “determination of a divided area” performed in step S11.

FIG. 5 is a flowchart showing the details of the processing in step S12.

FIG. 6 shows the hue, the saturation, and the brightness as x-axis, y-axis, and z, respectively.
FIG. 4 is a conceptual diagram showing a three-dimensional distribution of colors with respect to an axis.

FIG. 7: Hue axis (x-axis) and lightness axis (z-axis) for simplicity
FIG. 3 is a conceptual diagram of a two-dimensional display using only the information.

FIG. 8 is a flowchart illustrating details of step S12 in the second embodiment.

FIG. 9 is a conceptual diagram of a print image.

FIG. 10 shows a hidden pattern generator 8 according to the third embodiment.
5 is a flowchart showing the processing performed in step (a).

FIG. 11 is a conceptual diagram illustrating a part of a print image.

FIG. 12 shows a hidden pattern generation unit 8 in the fourth embodiment.
5 is a flowchart showing the processing performed in step (a).

FIG. 13 is a conceptual diagram illustrating an example of a print image.

FIG. 14 is a conceptual diagram illustrating elements constituting a “change pattern”.

FIG. 15 is a conceptual diagram illustrating a state in which an image is divided into a plurality of tiles 53 and a patch 51 is embedded for each tile 53 so as to represent a specific pattern corresponding to identification information.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Host computer 2 Printer 3 Operating system 4 Application program 5 GDI (Graphics Device Interface) module 6 Driver (print information generation device) 7 Print data generation part 8 Hidden pattern generation part 9 Embedding discrimination part 10 Interface part 11 Interface part 12 Interpretation Unit 14 image generation unit 15 printer engine 16 panel unit 17 status management unit 18 memory management unit 19 control unit 7A rasterizer 7B color correction processing unit 7C color correction table 7D halftone processing unit 7E interlace processing unit

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[Procedure amendment]

[Submission date] May 19, 1999 (1999.5.1
9)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

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FIG. 3

FIG. 4

FIG. 5

FIG. 6

FIG. 7

FIG. 8

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FIG.

FIG. 14

FIG.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/36 B41J 29/00 Z 5B057 21/00 560 G03G 21/00 382 5C076 G06T 1/00 G06F 15 / 66 B 5C077 H04N 1/40 H04N 1/40 Z 5C079 1/60 D 1/46 1/46 Z F term (reference) 2C061 AQ05 AR01 CL10 HK11 HN15 2C087 AA15 AC07 BA03 BA07 BD07 BD31 DA13 2H027 DE07 EE08 EE02 FA28 FA28 FD01 FD03 FD06 FD08 FD10 ZA07 ZA08 2H030 AD07 AD11 AD16 2H034 FA01 5B057 AA11 BA24 BA28 CA01 CA08 CA12 CA16 CA19 CB01 CB08 CB12 CB16 CE08 CE17 CH11 DA01 DA08 DA16 DB02 DB06 DB09 DC25 5C076 AAPPPPA36PP PQ08 PQ20 PQ22 RR18 5C079 HA18 HB02 LA02 LA07 LA10 LA31 LB11 PA02

Claims (10)

[Claims] An image processing apparatus for inputting data relating to a color image and outputting color print data to a printer capable of printing using color elements of a plurality of colors, comprising: An image processing apparatus comprising: a hidden pattern generation unit that embeds predetermined identification information as a hidden pattern therein; wherein the hidden pattern generation unit determines a color of the hidden pattern according to a background color of the print image. . 2. The hidden pattern generating means according to claim 1, wherein each of said plurality of color elements used by said printer and a combination of at least two of said plurality of color elements are color candidates, 2. The color of the color is determined as one of the color candidates.
The image processing apparatus according to any one of the preceding claims. 3. The hidden pattern generating unit determines a color having the closest lightness to the background color of the print image among the color candidates as a color of the hidden pattern. 3. The image processing device according to 2. 4. The apparatus according to claim 1, wherein said hidden pattern generation means determines a background color of said print image in accordance with the number of dots of said plurality of color elements. The image processing apparatus according to any one of the preceding claims. 5. The hidden pattern generating unit includes: a unit that divides the print image into a plurality of divided regions; and a unit that determines a background color of the divided region in which the hidden pattern is to be embedded, of the plurality of divided regions. The image processing apparatus according to any one of claims 1 to 4, further comprising: means for determining a color of the hidden pattern according to the determined background color. 6. The hidden pattern generating means: means for dividing an area of the print image in which the hidden pattern is to be embedded into a plurality of sampling areas; and determining a background color for each of the plurality of sampling areas. And means for determining a color of the hidden pattern corresponding to each of the plurality of sampling areas according to the determined background color. The image processing device according to any one of the above. 7. A means for analyzing a color distribution in at least a part of the print image, a means for determining a region in which the hidden pattern is to be embedded based on the analyzed color distribution. 5. The apparatus according to claim 1, further comprising: a unit configured to determine a background color of an area in which the hidden pattern is embedded, and a unit configured to determine a color of the hidden pattern according to the determined background color. 6. The image processing device according to any one of the above. 8. A printing system for inputting data relating to a color image and outputting it as a print image using a plurality of color elements, wherein a hidden pattern generating means for embedding predetermined identification information as a hidden pattern in the print image. And a hidden pattern generation unit that determines a color of the hidden pattern according to a background color of the print image. 9. A hidden pattern embedding method for embedding predetermined identification information as a hidden pattern in a color image, wherein a color of the hidden pattern is determined according to a background color of the color image. Embedding method. 10. A recording medium storing a program for inputting data relating to a color image and outputting color print data to a printer capable of printing using color elements of a plurality of colors, wherein the program comprises the color printing A hidden pattern generation step of embedding predetermined identification information as a hidden pattern in a print image included in the data, wherein the hidden pattern generation step determines a color of the hidden pattern according to a background color of the print image. Recording medium characterized by the above-mentioned.