JP3610269B2 - Image processing apparatus and image processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus and an image processing method for multiplexing image information, the image information, and predetermined additional information, and, for example, according to characteristics of a printer engine such as an ink jet printer, a hot-melt transfer printer, or a laser printer. The present invention relates to an image processing apparatus and an image processing method capable of expressing image information.
[0002]
[Prior art]
In recent years, the image quality of color printers and color copiers has been improved, and it has become possible to duplicate and faithfully reproduce printed matter. Therefore, the possibility of counterfeiting securities such as banknotes has increased, and various countermeasures have been taken.
[0003]
There are two types of anti-counterfeiting methods that have been used in the past: a method for recognizing securities and avoiding faithful printing of the current image, and adding the machine number of the printing device to the printed material. It can be divided into methods that make it possible to identify the aircraft that was used when the forgery was performed.
[0004]
Here, the technology for multiplexing identification information into image information is applied not only to forgery prevention technology such as securities, but also to various aspects such as copyright protection, protection of confidential information, and transmission methods of text, audio, etc. Various strategies have been proposed that are possible.
[0005]
Also, for example, as a conventional example regarding the control of addition of a code representing information, as a method described in Japanese Patent Laid-Open No. 5-14682, in the case of printing with achromatic color that is not used in forgery of securities, the body of the printing apparatus A method has been proposed in which information for preventing forgery such as a number is not added.
[0006]
[Problems to be solved by the invention]
However, in the above-described conventional code addition control method, code addition is performed even when information cannot be decoded depending on the image state if the output image is an image containing a chromatic color. For this reason, a sign addition process is always performed for an image including a chromatic color, and as a result, the printing speed is often lowered.
[0007]
In particular, when the code addition process is performed by software such as a printer driver instead of hardware having a relatively high processing speed, the influence is large.
[0008]
[Means for Solving the Problems]
The present invention has been made for the purpose of solving the above-described problems, and includes, for example, the following configuration as one means for achieving such an object.
[0009]
That is, in an image processing apparatus that multiplexes image information and additional information different from the image information, when adding a code using yellow ink from the black component density around the target pixel of the image information Decoding possibility determination means for determining whether or not decoding is possible, a determination result of the decoding possibility determination means, a pixel value around the target pixel of the image information, and the additional information to be multiplexed A quantization condition determining means for determining a quantization condition based on the quantization condition, and a quantization means for quantizing the pixel of interest of the image information by pseudo gradation processing under the quantization condition determined by the quantization condition determining means It is characterized by providing.
[0010]
In addition, in an image processing apparatus that multiplexes image information and additional information different from the image information, is decoding possible when code addition is performed from edge information around the target pixel of the image information? Quantization conditions are determined based on a decoding possibility determination unit that determines whether or not, a determination result of the decoding possibility determination unit, a pixel value around the target pixel of the image information, and the additional information to be multiplexed And a quantization means for quantizing the target pixel of the image information by pseudo gradation processing under the quantization condition determined by the quantization condition determination means. To do .
[0011]
Furthermore, the image processing method performs a multiplexing process of image information and additional information different from the image information, and adds a code using yellow ink from the black component density around the target pixel of the image information. A decoding possibility determination step for determining whether decoding is possible, a determination result of the decoding possibility determination step, a pixel value around the target pixel of the image information, and the additional information to be multiplexed A quantization condition determining step for determining a quantization condition based on the above, and a quantum for quantizing the pixel of interest of the image information by pseudo gradation processing under the quantization condition determined by the quantization condition determining step And a crystallization process .
[0012]
The image processing method performs multiplexing processing of image information and additional information different from the image information, and decoding is possible when code addition is performed from edge information around the target pixel of the image information. Decoding possibility determination step for determining whether or not there is a quantization condition based on the determination result of the decoding possibility determination step, the pixel value around the target pixel of the image information, and the additional information to be multiplexed A quantization condition determining step for determining the pixel of interest, and a quantization step for quantizing the target pixel of the image information by pseudo gradation processing under the quantization condition determined by the quantization condition determining step. Features .
[0013]
The present invention also provides a computer-readable storage medium storing a program for causing a computer to execute the image processing method .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
(Embodiment of the first invention)
FIG. 1 is a schematic block diagram showing the configuration of the image processing apparatus according to the first embodiment of the present invention. In FIG. 1, reference numeral 10 denotes an image information supply unit for supplying image information to be processed, and all configurations capable of supplying a processed image, such as a scanner, a CD-ROM, an optical disk, and a magnetic disk, correspond.
[0018]
Reference numeral 20 denotes an image input unit which inputs image information and the like from various image supply units 10, separates them into image information and additional information, and supplies them to the image quantization unit 30. Reference numeral 30 denotes an image quantization unit that receives image information from the image input unit 20 and additional information different from the image information and performs a multiplexing process, and performs code addition from pixel values around the target pixel of the image information. In this case, it is determined whether decoding is possible, a quantization condition is determined based on the determination result and the additional information to be multiplexed with a pixel value around the target pixel of the image information, and under the determined quantization condition The pixel of interest of the image information is quantized by pseudo gradation processing.
[0019]
Reference numeral 40 denotes an image output unit that outputs image information quantized by the image quantization unit 30. The image output unit 40 is a printing apparatus such as an ink jet printer that forms an image using pseudo gradation expression.
[0020]
The detailed configuration of the image quantization unit 30 will be described below with reference to FIG. FIG. 2 is a block diagram showing a detailed configuration of the image quantization unit 30 shown in FIG.
[0021]
In FIG. 2, reference numeral 100 denotes an input terminal for inputting image information. Reference numeral 101 denotes an input terminal for inputting additional information such as identification information. Reference numeral 102 denotes a decodability determination unit that detects the image density of the code addition region and determines whether the added code is decodable, and is referred to when determining the quantization condition.
[0022]
Reference numeral 103 denotes quantization condition determining means for determining a quantization condition for quantizing the image information. Reference numeral 104 denotes quantization means for quantizing the image information. The image information is quantized by a method such as an error diffusion method under the quantization condition determined by the quantization condition determination means 103. Reference numeral 105 denotes an output terminal for outputting quantized image information.
[0023]
Here, the error diffusion method is a method in which multi-valued image information is expressed in a pseudo gradation with two or less quantized values than input image information, and occurs when the pixel value of interest is quantized. This is a quantization method for storing image density by distributing an error to pixels around a pixel of interest.
[0024]
FIG. 3 shows an example of an error distribution matrix of the error diffusion method used in this embodiment. In FIG. 3, “*” represents the position of the target pixel, “a” to “l” represent the distribution ratio of the quantization error generated in the target pixel, and the error according to the distribution ratio is calculated around the target pixel. Distribute to pixels.
[0025]
In the example shown in FIG. 3, the error is distributed to the range of two pixels from the target pixel both vertically and horizontally. However, the error diffusion method of the present embodiment is not limited to the example shown in FIG. 3, and an arbitrary error distribution range can be adopted.
[0026]
The image information processing method of the present embodiment having the above configuration will be described below with reference to the flowchart of FIG. FIG. 4 is a flowchart showing an operation procedure of the image quantization unit 30 of the present embodiment shown in FIG.
[0027]
In FIG. 4, an initialization process is performed in step S300. Step S300 shows initialization of variables (i, j) for counting addresses in the vertical and horizontal directions. In step S301, it is determined from the address value whether (i) is a sign addition row. Here, it is determined whether or not the code is added to the row address (i). If (i) is a code-added row, the process proceeds to step S302 to determine whether (j) is a code-added column. Step S302 is also a determination unit based on an address value similar to that in step S301, and determines whether or not the column address (j) is a column to which a code is added based on the address value.
[0028]
If it is determined in step S301 and step S302 that the position is the code addition position, the process proceeds to step S303, and the image density around the target pixel is detected in step S303. In step S304, the decoding possibility of the additional code when the code is added from the image density around the target pixel is determined. If it is determined that decoding is possible, the process proceeds to step S305, and a quantization condition for adding a code is acquired. Then, the process proceeds to step S306.
[0029]
On the other hand, if it is determined in step S301 and step S302 that it is not a place where code addition is performed and if it is determined that decoding is not possible in step S304, the process proceeds to step S307 and normal quantization conditions in which code addition is not performed. And proceeds to step S306.
[0030]
In step S306, pseudo gradation processing is performed on the image information in accordance with the quantization condition acquired in step S305 or step S307. In step S308, the column address (j) is incremented by one. In step S309, it is determined whether the column address (j) is equal to or larger than the size “m” in the column direction of the image information to check whether the column direction processing is completed. If the process in the column direction has not been completed, the process proceeds to step S302, and the quantization process for the next column is performed.
[0031]
Note that when the quantization conditions acquired in step S305 and step S307 are compared, the quantization condition acquired in step S307 is faster in the pseudo gradation processing executed in step S306.
[0032]
On the other hand, if the process in the column direction has been completed in the determination in step S309, the process proceeds to step S310. In step S310, the column address j is initialized. In step S311, the row address (i) is incremented by one. Next, in step S312, it is determined whether the row address (i) is equal to or larger than the size “n” in the column direction of the image information, and it is checked whether the process in the row direction is completed. If processing has not been completed for all the rows, the process proceeds to step S301, and quantization processing for the next row is performed.
[0033]
On the other hand, if the quantization process for all the rows has been completed in step S312, the process ends.
[0034]
Next, an example of adding different kinds of information to image information in the present embodiment will be described with reference to FIG. FIG. 5 shows an example of an information block embedded in the image information so as to be hardly visible in the present embodiment. The information block is a unit of information to be added, and is, for example, a printer identification number for preventing forgery of securities.
[0035]
In the information block, codes composed of a plurality of dots are arranged according to a specific regularity. In addition, when used for forgery prevention, the information block in FIG. 5 is embedded so as to be difficult to see in the entire image information.
[0036]
The information block in FIG. 5 expresses information by arrangement of codes in a range surrounded by four symbols with continuous codes, and there are rows where codes are added at regular intervals in the vertical direction. . Then, a bit is expressed depending on whether the number of codes in the code addition row is an even number or an odd number. Here, in the technology for preventing the forgery of securities that need to reliably detect information in an image, the information block may be repeatedly embedded in the entire image information. Must be created.
[0037]
When ink is used for printing, such as an ink jet printer, an ink dot corresponding to the quantized value is printed after image processing is performed with a binary or low-level quantized value by performing pseudo gradation processing. . A code added to the print image is also formed by a set of dots.
[0038]
Here, when liquid ink is used for printing, the ink spreads on the recording medium at the time of printing, so that off dots that are not struck on the printed image may be crushed. For this reason, it is desirable that the dots forming the code are on-dots that strike ink.
[0039]
However, when the image density becomes high in the color component for creating the code, the on-dot is buried in the image information and cannot be detected. That is, the code becomes meaningless in the high density region, and as a result, the code addition process becomes useless. Therefore, the processing time can be shortened by detecting the image density and not performing the code addition process when the code is an undetectable image density.
[0040]
FIG. 6 is a diagram illustrating an example of information addition according to image density in the code addition processing according to the present embodiment. In the example shown in FIG. 6, the image is added to the entire information image information, and in the image density region where the code cannot be detected, the code creation process is not performed and only the normal pseudo gradation process is performed.
[0041]
The information blocks shown in FIGS. 5 and 6 show an embodiment of the present invention, and the present invention is not limited to the above embodiment.
[0042]
As described above, according to one embodiment of the present invention, if the code generation is controlled according to the image density of the code addition region and the code is added, the code can be detected. Since code addition can be performed and no code addition can be performed if the code cannot be detected, the printing process can be speeded up.
[0043]
(Second Embodiment)
In a printing apparatus such as an ink jet printer or a color laser printer, color images are printed using C (Cyan), M (Magenta), Y (Yellow), or K (Black) ink or toner. Do. Here, even when the code is added by the same method, the way it visually stands out differs depending on the printed color components.
[0044]
For example, when dots are printed on white paper, if K ink is used, it is visually noticeable, but if Y ink is used, it is not visually noticeable. Therefore, when adding information such as the machine number that has been printed to prevent forgery of securities, it is preferable to create a code with Y ink, which is the least visually noticeable.
[0045]
Here, if C, M, and Y, which are essentially complementary colors, are mixed together, the color becomes black. However, K ink is often used because the actual ink does not become completely black. Still, in an actual ink jet printer, when C, M, and Y inks are mixed, a color close to K is printed.
[0046]
As a result, even if a print image is read by a scanner and color-separated to extract a Y component area as a code-added color, it is possible to distinguish between when C, M, and Y are hit simultaneously and when only K is hit. In some cases, it is determined that the K ink dot is hit with Y ink.
[0047]
Therefore, a dot pattern having a shape similar to a code appears in an area where a code is not generated in the code-added color component, which may cause erroneous detection of information. Further, as described in the first embodiment, even when it is determined that the code-added color density is low and code detection is possible, if the K ink component is added to the same region, In the code-added color component of an image obtained by reading a print image with a scanner, the density of the code-added color becomes high, and the code may not be read.
[0048]
Therefore, in the second embodiment according to the present invention, meaningless code generation is not performed by controlling the execution of the code addition process according to the density of the K ink component of the image information during the code addition process. Can be.
[0049]
In the second embodiment, the basic configuration is the same as that of the first embodiment described above, and only the parts different from the first embodiment will be described below. In the second embodiment, the operation contents of the decryptability determination unit 102 shown in FIG. 2 are different.
[0050]
FIG. 7 is a flowchart showing the operation procedure of the second embodiment of the present invention. In FIG. 7, the same steps as those in the first embodiment shown in FIG. 4 described above are denoted by the same step numbers, and detailed description thereof is omitted.
[0051]
In FIG. 7, the difference from the first embodiment shown in FIG. 4 is that in step S301 and step S302, (i) row is a row to which code is added, and (j) column is a column to which code is added. If there is, the process proceeds to step S600 instead of step S303, and the density of the K ink component around the target pixel is detected in step S600. Then, the process proceeds to step S304. In step S304, the decoding possibility of the additional code when the code is added is determined from the result of step S600. Other processes are the same as those in the first embodiment.
[0052]
According to the second embodiment, as described above, since code generation is not performed in an area where a code cannot be detected due to the influence of the K ink component, efficient processing can be performed without performing useless processing.
[0053]
(Third embodiment)
Next, a description will be given of a third embodiment according to the present invention in which special quantization processing is performed when the information block covers an edge portion of image information.
[0054]
When the information block covers the edge portion of the image information, the arrangement of dots appearing at the edge portion in the image information varies depending on the image density on both sides of the edge, the sharpness of the edge, etc. .
[0055]
For this reason, it may occur that a code expressed by the arrangement of specific dots cannot be detected around a certain edge due to the influence of surrounding dots. For example, when the arrangement of the dots forming the code is a dispersed arrangement, there is a possibility that the dot arrangement of the image information is confused near the blurred edge that occurs in the natural image. Further, the arrangement of the dots forming the code is an arrangement in which the dots are concentrated, and there is a possibility that the edge is buried when the code addition region is on the high density side of the edge. Therefore, in the third embodiment, it is wasted by controlling not to create a code when there is a possibility that decoding may be difficult when an edge exists around the code addition region. Efficient image processing is realized without processing.
[0056]
Also in the third embodiment, the basic configuration is the same as that of the first embodiment shown in FIG. 1 and FIG. 2 described above, and different parts from the first embodiment will be described below. In the third embodiment, the operation contents of the decryptability determination unit 102 shown in FIG. 2 are different.
[0057]
FIG. 8 is a flowchart showing the operation procedure of the third embodiment of the present invention. In FIG. 8, the same step numbers are assigned to the processes similar to those in the first embodiment shown in FIG. 4 described above, and detailed description thereof is omitted.
[0058]
In FIG. 8, the difference from the first embodiment shown in FIG. 4 is that in step S301 and step S302, (i) row is a row to which code is added, and (j) column is a row to which code is added. If there is, the process proceeds to the process of step S700 instead of the process of step S303. In step S700, the state of the image around the target pixel is investigated, and an edge is detected. Then, the process proceeds to step S304.
[0059]
In step S304, the decoding possibility of the additional code when the code is added is determined from the result of step S700. If it is determined that decoding is possible, the process proceeds to step S305. If it is determined that decoding is impossible, the process proceeds to step S307. Other processes are the same as those in the first embodiment.
[0060]
FIG. 9 is a diagram illustrating an example of information addition according to edge detection in the code addition processing according to the third embodiment. In the example shown in FIG. 9, the image information is divided into a low density area and a medium density area with an edge as a boundary, and is an output example when an information block including an edge portion is not created.
[0061]
Of course, even if the creation control is performed in units of codes as shown in FIG. 6 of the embodiment of the first embodiment described above, there is an effect.
[0062]
As described above, according to the third embodiment, when there is an edge around the code addition region, code addition can be controlled according to the type of the edge. Addition can be realized.
[0063]
(Other embodiment examples)
Note that the present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, and a printer), and a device (for example, a copying machine and a facsimile device) including a single device. You may apply to.
[0064]
Another object of the present invention is to supply a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded to a system or apparatus, and the computer (or CPU or CPU) of the system or apparatus. Needless to say, this can also be achieved by the MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.
[0065]
Further, after the program code read from the storage medium is written in a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.
[0066]
When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowcharts shown in FIGS. 4, 7, and / or 8 described above.
[0067]
【The invention's effect】
As described above, according to the present invention, when heterogeneous information is multiplexed in image information in which the image information is represented by pseudo gradation, the execution of the process of adding the code representing the information is performed to the image density of the code-added color. By changing accordingly, efficient information addition with little waste can be realized.
[0068]
In addition, when a printing apparatus including K ink is used, efficient information addition with little waste can be realized by controlling the execution of the code addition process according to the density of the K ink component.
[0069]
Furthermore, efficient information addition with little waste can be realized by controlling the execution of the code addition process according to the type of edge in the image information.
[0070]
Furthermore, it is possible to efficiently add information with little waste by determining the possibility that the predetermined information added to the image information is detected and adding the predetermined information according to the determination possibility. realizable. In addition, there is no risk of image quality degradation. Furthermore, the added information can be read.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing the configuration of an image processing apparatus according to a first embodiment of the present invention.
FIG. 2 is a block diagram illustrating a detailed configuration of an image quantization unit illustrated in FIG. 1;
FIG. 3 is a diagram illustrating an example of an error distribution matrix of an error diffusion method used in the present embodiment.
4 is a flowchart showing an operation procedure of an image quantization unit of the embodiment shown in FIG.
FIG. 5 is a diagram illustrating an example of an information block in the present embodiment.
FIG. 6 is a diagram illustrating an example of information addition according to image density in the code addition processing according to the present embodiment.
FIG. 7 is a flowchart showing an operation procedure of the second embodiment according to the present invention.
FIG. 8 is a flowchart showing an operation procedure of the third embodiment according to the present invention.
FIG. 9 is a diagram illustrating an example of adding information to an edge portion in the third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Image information supply part 20 Image input part 30 Image quantization part 40 Image output part 100 Input terminal 101 which inputs image information Input terminal 102 which inputs additional information, such as identification information 102 Decoding possibility determination means 103 Quantization condition determination means 104 Quantization means 105 Output terminal

Claims (7)

In an image processing apparatus that performs multiplexing processing of image information and additional information different from the image information,
Decodeability determination means for determining whether or not decoding is possible when code addition is performed using yellow ink from the black component density around the target pixel of the image information;
A quantization condition determining unit that determines a quantization condition based on a determination result of the decoding possibility determination unit, a pixel value around the target pixel of the image information, and the additional information to be multiplexed;
Quantization means for quantizing the pixel of interest of the image information by pseudo gradation processing under the quantization condition determined by the quantization condition determination means;
An image processing apparatus comprising: In an image processing apparatus that performs multiplexing processing of image information and additional information different from the image information,
Decoding possibility determination means for determining whether or not decoding is possible when code addition is performed from edge information around the target pixel of the image information;
A quantization condition determining unit that determines a quantization condition based on a determination result of the decoding possibility determination unit, a pixel value around the target pixel of the image information, and the additional information to be multiplexed;
Quantization means for quantizing the target pixel of the image information by pseudo gradation processing under the quantization condition determined by the quantization condition determination means;
The image processing apparatus comprising: a. The image processing apparatus according to claim 1, wherein the quantization unit quantizes the pixel of interest by pseudo gradation processing based on an error diffusion method . An image processing method for performing multiplexing processing of image information and additional information different from the image information,
A decodability determination step of determining whether decoding is possible when code addition is performed using yellow ink from the black component density around the target pixel of the image information;
A quantization condition determination step for determining a quantization condition based on a determination result of the decoding possibility determination step, a pixel value around the target pixel of the image information, and the additional information to be multiplexed;
A quantization step of quantizing the target pixel of the image information by pseudo gradation processing under the quantization condition determined by the quantization condition determination step;
An image processing method comprising: An image processing method for performing multiplexing processing of image information and additional information different from the image information,
A decoding possibility determination step for determining whether decoding is possible when code addition is performed from edge information around the target pixel of the image information;
A quantization condition determining step for determining a quantization condition based on a determination result of the decoding possibility determination step, a pixel value around the target pixel of the image information, and the additional information to be multiplexed;
A quantization step of quantizing the target pixel of the image information by pseudo gradation processing under the quantization condition determined by the quantization condition determination step;
An image processing method comprising: A computer-readable storage medium storing a program for causing a computer to execute the image processing method according to claim 4. A computer-readable storage medium storing a program for causing a computer to execute the image processing method according to claim 5.

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