Image processing apparatus and image processing method

Abstract

To embed a plurality of types of information in a printing manuscript without using special configuration, or to extract a plurality of types of information embedded in a printing manuscript without using special configuration.SOLUTION: An image processing device comprises: first acquisition means acquiring a manuscript image; second acquisition means acquiring a first multiplexed image in which first information is embedded in an original manuscript image by a first method in which the shape of a pattern changes; third acquisition means acquiring a second multiplexed image in which second information of a type different from the first information is embedded in the first multiplexed image by a second method in which the density of the pattern changes; and control means causing printing means to perform printing using the second multiplexed image.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a technique for handling information embedded in a printed document (hereinafter referred to as a printed manuscript).

Background Art

[0002] When printing an electronic document on paper, a technique for embedding information by multiplexing is known. Patent Document 1 describes a technique for embedding two different types of additional information in the same printed manuscript by two different means, and a technique for reading out the additional information from the same manuscript. More specifically, Patent Document 1 describes a technique for embedding the first additional information by the print density in the visible light region and the second additional information by the print density in the non-visible light region.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique of Patent Document 1, it is necessary to provide a non-visible light reading means separately from the visible light reading means.

[0005] An object of the present disclosure is to embed a plurality of types of information in a printed manuscript or extract a plurality of types of information embedded in a printed manuscript without using a special configuration.

Means for Solving the Problems

[0006] An image processing apparatus according to one aspect of the present disclosure includes: a first acquisition means for acquiring an original image; a second acquisition means for acquiring a first multiplexed image in which first information is embedded in the original image by a first method of which the shape of the pattern changes; a third acquisition means for acquiring a second multiplexed image in which second information of a different type from the first information is embedded in the first multiplexed image by a second method of which the density of the pattern changes; and a control means for performing control to output print data for a print original using the second multiplexed image. The second acquisition means further acquires region information indicating a first region that is read relatively darker when reading the print original and a second region that is read relatively lighter than the first region. The first information is embedded in the original image by switching and embedding a plurality of patterns in which the shape of the pattern changes in the first region, and the first multiplexed image is obtained in which a pattern in which the number of pixels recorded in adjacent pixels is less than that in the first region is embedded in the second region. The control means performs control to output the print data using the second multiplexed image. It is characterized by the following: [Effects of the Invention]

[0007] According to this disclosure, multiple types of information can be embedded in a print document without using a special configuration. Furthermore, multiple types of information can be extracted from a print document without using a special configuration. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing the configuration of the recording system. [Figure 2] This figure shows an example of an external view of an MFP (Multi-Function Product Processor). [Figure 3] This is a flowchart illustrating the information embedding process and the information extraction process. [Figure 4] This figure shows an example of a manuscript corresponding to document data. [Figure 5] The figure shows an example of a mask. [Figure 6] This figure shows an example of a pattern given by a mask, visually represented. [Figure 7] The figure shows an example of a mask. [Figure 8] This diagram visually represents the pattern given by the mask. [Figure 9] The figure shows an example of a mask. [Figure 10] This diagram visually represents the pattern given by the mask. [Figure 11] This figure shows an example of embedding a pattern. [Figure 12] It is a diagram showing the result of multiplexing processing. [Figure 13] It is a diagram showing an example of a filter. [Figure 14] It is a diagram showing an example of the result of applying a filter. [Figure 15] It is a diagram showing an example of a filter. [Figure 16] It is a diagram showing an example of the result of applying a filter. [Figure 17] It is a diagram showing an example of the result of applying a filter. [Figure 18] It is a flowchart explaining the information embedding process. [Figure 19] It is a diagram showing an example of ground pattern area information. [Figure 20] It is a flowchart showing the details of the multiplexing process of the ground pattern and the document ID. [Figure 21] It is a diagram showing a mask. [Figure 22] It is a diagram visually showing the pattern given by the mask. [Figure 23] It is a diagram explaining multiple embedding positions.

Mode for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the present disclosure, and not all combinations of the features described in the following embodiments are essential for the solution means of the present disclosure.

[0010] <<First Embodiment>> Figure 1 is a block diagram showing the configuration of the recording system of this embodiment. The recording system of this embodiment includes a host PC 50 and an MFP 10. The host PC 50 and the MFP 10 are configured to communicate with each other. The MFP 10 is a Multi Function Printer, which is a recording device. Generally, the MFP 10 refers to a printer that has multiple functions, such as a printer function and a scanner function, and often also has a copy function that performs both functions in coordination. The host PC 50 is the host device for the MFP 10 and is an information processing device such as a personal computer. In this embodiment, as will be described later, image processing is performed to embed information in the print document, or image processing is performed to extract information embedded in the print document. In this embodiment, both the host PC 50 and the MFP 10 can function as image processing devices that perform these image processing operations. The hardware configurations of the MFP 10 and the host PC 50 will be described below.

[0011] Figure 2 shows an example of the external view of the MFP10. In this embodiment, the printing method of the MFP10 is an inkjet method. The MFP10 also has a scanner unit 12 and a print unit 13. The print unit 13 has a recording head 14 and an ink tank unit 15. The recording head 14 ejects ink according to the recording data. The ink tank unit 15 stores the ink supplied to the recording head 14. In this embodiment, the inks stored are cyan, magenta, yellow, and black. Note that the examples of inks are not limited to these, and depending on the model, spot colors and other inks may be stored separately.

[0012] Returning to Figure 1, let's continue the explanation of the hardware configuration. The host PC 50 has a CPU 501, RAM 502, HDD 503, DATA TRANSFER I / F 504, KEYBOARD MOUSE I / F 505, DISPLAY I / F 506, and NETWORK I / F 507.

[0013] The CPU 501 executes processing according to the program stored in the HDD 503 or RAM 502. RAM 502 is volatile storage that temporarily holds programs and data. HDD 503 is non-volatile storage that holds programs and data. The DATA TRANSFER I / F (Data Transfer Interface) 504 controls the transmission and reception of data between the MFP 10 and the CPU. This data transmission and reception connection can be via a wired connection such as USB, IEEE1394, or LAN, or a wireless connection such as Bluetooth or WiFi. The KEY BOARD MOUSE I / F (Keyboard / Mouse Interface) 505 is an interface that controls a HID (Human Interface Device) such as a keyboard or mouse. The user can input via this KEY BOARD MOUSE I / F 505. The DISPLAY I / F (Display Interface) 506 controls the display on the display (not shown). The Network Interface (Network I / F) 507 connects the host PC 50 to an external network, communicates with one or more external PCs, and performs tasks such as requesting document ID verification, requesting results, and requesting document data. Note that the example shown in Figure 1 is merely one example; the host PC 50 can be any device that functions as an information processing device. For example, a smartphone or tablet terminal may be used as the information processing device.

[0014] The MFP10 includes a CPU101, RAM102, ROM103, DATA TRANSFER I / F104, HEAD Controller105, and ImageProcessingAccelerator106. It also includes a SCANNER Controller107 and a MOTOR Controller108.

[0015] The CPU 101 executes the processes described later in Figure 3 and beyond, according to the programs stored in ROM 103 or RAM 102. RAM 102 is volatile storage that temporarily holds programs and data. ROM 103 is non-volatile storage that can hold table data and programs used in the processes described later in Figure 3 and beyond.

[0016] The DATA TRANSFER I / F (Data Transfer Interface) 104 controls the transmission and reception of data between the host PC 50 and the printer. The HEAD Controller 105 controls the heating operation of the heater mounted on the recording head 14 based on the recorded data, and ejects ink. Specifically, the HEAD Controller 105 can be configured to read control parameters and recorded data from a predetermined address in the RAM 102. When the CPU 101 writes the control parameters and recorded data to the predetermined address in the RAM 102, the HEAD Controller 105 starts processing, and the heating operation of the heater mounted on the recording head 14 is performed. The ImageProcessingAccelerator 106 is a hardware component that performs image processing at a higher speed than the CPU 101. Specifically, the ImageProcessingAccelerator 106 can be configured to read the parameters and data necessary for image processing from a predetermined address in the RAM 102. Then, when the CPU 101 writes the above parameters and data to the predetermined address in RAM 102, the ImageProcessingAccelerator 106 is activated and the predetermined image processing is performed. Note that the ImageProcessingAccelerator 106 is not necessarily an essential element, and depending on the printer specifications, the above image processing may be performed solely by the CPU 101. In this embodiment, an inkjet recording device that records images by ejecting ink is described as an example of a recording device, but a recording device that applies ink to the medium by other methods may also be used. Alternatively, an electrophotographic recording device that records images using toner may also be used.

[0017] The SCANNER Controller 107 controls the scanner unit 12, which functions as a reading device. For example, it instructs the scanner unit 12 to illuminate the document with light and to transmit the light intensity information acquired by the image sensor such as a CCD from the reflected light to the SCANNER Controller 107. Specifically, when the CPU 101 writes the control parameters and the read data write address to the predetermined address in the RAM 102, the SCANNER Controller 107 starts processing. Then, the LED mounted on the scanner unit 12 is controlled to emit light, light intensity information is acquired from the scanner unit 12, and light intensity information is written to the read data write address and subsequent addresses in the RAM 102.

[0018] The MOTOR Controller 108 controls the operation of multiple motor units (not shown). The motors are used to move the recording head 14 relative to the recording paper, and to move the scanner unit 12 relative to the document being scanned, among other things. In addition, some MFPs may be equipped with a motor for maintenance of the recording head.

[0019] In this embodiment, we will describe examples of embedding the following two types of information in a print original (print document). ·Authentic document ID information ·Device information Authentic document ID information is ID information that indicates that the document is an authentic document. Hereinafter, authentic document ID information will also be simply referred to as document ID. The document ID is also an ID that identifies the document. Equipment information is model information such as the model name of the MFP device 10, or information related to printing processes such as the print mode. Hereinafter, document ID may be referred to as first information and equipment information as second information, but it is also acceptable to refer to document ID as second information and equipment information as first information. The source of first information and second information may be different. Also, the systems for extracting embedded information may be different. For this reason, first information and second information are required to be treated as separate and independent information. Furthermore, first information and second information are not limited to the examples above, and any information can be treated as first information and second information.

[0020] Figure 3 is a flowchart illustrating the information embedding process and information extraction process for document ID and device information in this embodiment. The series of processes shown in the flowchart of Figure 3 are performed by the CPU 101 of the MFP 10 expanding the program code stored in the ROM 103 or the like into the RAM 102 and executing it. The symbol "S" in the description of each process means that it is a step in the flowchart (the same applies throughout this specification). Figure 3(a) is a flowchart of the information embedding process. Figure 3(b) is a flowchart of the information extraction process. Figures 3(a) and 3(b) are processes that are performed separately and independently. Note that all of the processes shown in Figure 3 may be performed by the host PC 50. If performed by the host PC 50, the printing process (S3008) and document reading process (S3101) described later may be replaced with the printing command output process and document reading command output process from the host PC 50 to the MFP 10. Furthermore, some of the processes shown in Figure 3 may be performed by the host PC 50, while others may be performed by the MFP 10. For example, in Figure 3(a), processes S3001 to S3007 may be performed by the host PC 50, and process S3008 may be performed by the MFP 10. Also, in Figure 3(b), process S3101 may be performed by the MFP 10, and processes S3102 to S3112 may be performed by the host PC 50. In the following explanation, we will use an example in which the processes shown in Figure 3 are performed by the MFP 10.

[0021] <Information Embedding Processing> First, let's explain the information embedding process. In S3001, the MFP10 acquires document data. Specifically, in this embodiment, the host PC50 connects to an external PC (not shown) via the NETWORK I / F507, requests document data, and acquires the document data from the external PC. The host PC50 sends a command to the MFP10 to print this acquired document data. In S3001, the MFP10 acquires the document data sent from the host PC50 in this manner.

[0022] In this example, the document data is assumed to be written in PDL. PDL stands for Page Description Language, and it consists of sets of drawing commands on a page-by-page basis. The types of drawing commands are defined according to the PDL specification, but in this embodiment, the following three types are mainly used as examples. Command 1) Text drawing command (X1, Y1, X2, Y2, color, font information, string information) Command 2) Box drawing command (X1, Y1, X2, Y2, color, fill shape) Command 3) IMAGE drawing command (X1, Y1, X2, Y2, image file information) In addition, drawing commands such as the DOT command for drawing points, the LINE command for drawing lines, and the CIRCLE command for drawing arcs are used as appropriate depending on the application.

[0023] Commonly used PDLs include PDF (Portable Document Format) proposed by Adobe, XPS proposed by Microsoft, and HP-GL / 2 proposed by HP. In this embodiment, any PDL can be used, and other PDLs may also be applied.

[0024] Figure 4 shows an example of a manuscript corresponding to document data. In Figure 4, manuscript 400 represents one page of the document data, with a resolution of 600 pixels in width and 900 pixels in height. Below is an example of a PDL corresponding to the document data representing manuscript 400 in Figure 4. <PAGE=001> <text>50,50, 200, 100, BLACK, STD-18, "ABCDEFGHIJKLMNOPQR”< / text> <text>50,100, 200, 150, BLACK, STD-18, "abcdefghijklmnopqrstuv”< / text> <text>50,150, 200, 200, BLACK, STD-18, "1234567890123456789”< / text> <box> 50, 300, 200, 450, GRAY, STRIPE< / box> 250, 300, 550, 800, “PORTRAIT.jpg”

[0025] First line<PAGE=001> This tag represents the page number in this embodiment. Typically, PDL data is designed to describe multiple pages, so tags indicating page breaks are included in the PDL data. In this example, it indicates that the first page is up to line 9. In this example, the first page corresponds to manuscript 400 in Figure 4. If a second page exists, it follows the above PDL.<PAGE=002> This will be described.

[0026] Second line <text> From the third line< / text> Up to this point, it is drawing command 1, which corresponds to the first line of text in object 401 in Figure 4. The first two coordinates indicate the top-left coordinates (X1, Y1) of the drawing area, and the following two coordinates indicate the bottom-right coordinates (X2, Y2) of the drawing area. Next, it is stated that the color is BLACK (black: R=0, G=0, B=0) and the font of the text is "STD" (standard). It is also stated that the font size is 18 points and that the text to be written is "ABCDEFGHIJKLMNOPQR".

[0027] Fifth line <text> From the 6th line< / text> Up to this point, it is drawing command 2, which corresponds to the string on the second line of object 401 in Figure 4. The first four coordinates and the two strings represent the drawing area, text color, and text font, respectively, just like in drawing command 1. It also states that the string to be written is "abcdefghijklmnopqrstuv".

[0028] Line 7 <text> From the 8th line< / text> Up to this point, it is drawing command 3, which corresponds to the string on the third line of object 401 in Figure 4. The first four coordinates and the two strings represent the drawing area, text color, and text font, respectively, just like drawing command 1 and drawing command 2. It is also stated that the string to be written is "1234567890123456789".

[0029] Line 9 <box> from< / box>Up to this point, it is drawing command 4, which corresponds to object 402 in Figure 4. The first two coordinates indicate the top-left coordinates (X1, Y1), which are the starting point of the drawing, and the following two coordinates indicate the bottom-right coordinates (X2, Y2), which are the ending point of the drawing. Next, the color is specified as GRAY (R=128, G=128, B=128), and the fill shape is specified as STRIPE (striped pattern). In this embodiment, the direction of the stripes is always a line towards the bottom right, but the angle and period of the line may be made possible within the BOX command.

[0030] Next, the IMAGE command on line 10 corresponds to object 403 in Figure 4. Here, it is stated that the filename of the image in that area is "PORTRAIT.jpg". This indicates that it is a JPEG file, a commonly used image compression format.

[0031] The 11th line indicates that the rendering of the page has finished.

[0032] In addition to the drawing commands described above, actual PDL files often include "STD" font data and a "PORTRAIT.jpg" image file as a single integrated file. This is because if the font data and image files were managed separately, the drawing commands alone would not be sufficient to form the text and image portions, resulting in insufficient information to create the image of original document 400 in Figure 4. The above explains the document data acquired by S3001 in Figure 3.

[0033] In S3002, MFP10 obtains a document ID, which indicates the authenticity of the document data acquired in S3001. The document ID can be information calculated based on all document files, including the PDL file, font data, and image files mentioned above. In this embodiment, the document ID is 256 bits of information. The method for calculating this document ID is designed so that if any of the files constituting the document are changed, the calculated document ID will have a different value. Therefore, each document file will have a unique document ID. Specifically, in this embodiment, MFP10 requests the document ID from the external PC from which the host PC50 acquired the document file, and receives the document ID. Alternatively, MFP10 may obtain the document ID from the host PC50. It may also obtain the document data and document ID together.

[0034] Another implementation method involves using a blockchain-like configuration where document data and document IDs are managed on multiple external PCs, and the host PC 50 requests document IDs from these multiple PCs. The MFP 10 can then acquire the document data and document IDs obtained by the host PC 50 in this manner. By using a blockchain-like mechanism, the risk of tampering with the document IDs themselves can be reduced.

[0035] Next, in S3003, the MFP10 performs rendering processing on the document data acquired in S3001. Rendering processing involves executing each drawing command described in the PDL data to form a Bitmap image composed of color information for each pixel. In this embodiment, as described above, the original document 400 in Figure 4 consists of 600 pixels in width and 900 pixels in height, so the Bitmap image generated in this step consists of 600 x 900 pixels. Each pixel also has 256 gradations with 8 bits each for R / G / B.

[0036] In S3004, MFP10 performs a multiplexing process to generate a multiplexed image (also called the first multiplexed image) in which the document ID is multiplexed. This multiplexing process is also referred to as embedding. Specifically, the multiplexed image is generated by superimposing the document ID obtained in S3002 onto the bitmap image generated by rendering in S3003. The reason for performing the multiplexing process is that when the output (printed original) of the multiplexed image is copied using a copier, the copier can extract the document ID from the scanned printed original. Using such a multiplexed image, it becomes possible to determine, for example, whether the printed original itself is based on a digital document managed by a document ID.

[0037] In this embodiment, embedded information is treated as binary data and superimposed on a Bitmap image. Binary data is explained below. Handling information with an information processing device such as a PC specifically means handling binary data. Binary data is information consisting of "0"s or "1"s, and when this "0" or "1" information is linked together in sequence, it acquires a specific meaning. For example, when handling the information "hello" as binary data, taking "Shift JIS," one of the character encodings, as an example, "h" corresponds to the binary data "01101000". Similarly, "e" corresponds to the binary data "01100101", "l" to "01101100", and "o" to "01101111". In other words, the characters "hello" can be represented in binary data as "0110100001100101011011000110110001101111". Conversely, if we can obtain the binary data "0110100001100101011011000110110001101111", we can obtain the string "hello". Based on this idea, it can be seen that multiplexing can be achieved by embedding data in a way that allows for the determination of either "0" or "1".

[0038] Here, we consider the two masks shown in Figure 5 to generate "0" and "1". Figures 5(a) and 5(b) each show one mask. The mask shown in Figure 5 is composed of 8px (pixels) × 8px, and by adding the contents of the mask to the image, a periodic pattern can be given to the 8px × 8px area within the image. Basically, digital images are represented with 1 color and 8 bits, and one of the values ​​from 0 to 255 is assigned. Values ​​outside this range cannot be used as image data, so if the calculation result of the pixel value is less than 0, or if it is a value of 256 or more, 0 or 255 is generally assigned, keeping the value within the valid range. In the mask in Figure 5, the pixel value is changed to -64 or 0, but if all the image data values ​​in the mask area are 0, the values ​​in that area will not be -64 and 0, but all will be 0. Note that this explanation is based on the example of 1 color and 8 bits, but of course, other bits are also possible. Even in that case, when dealing with digital images, there is a valid range regardless of the number of bits used for representation, and the same principle applies in that changes outside that range cannot be applied.

[0039] Figure 6 shows an example of a pattern visually represented by a mask on the white areas of a print document. Figure 6(a) corresponds to the mask in Figure 5(a), and Figure 6(b) corresponds to the mask in Figure 5(b). In Figure 6, the position of "-64" in the mask of Figure 5 is represented by a black pixel, and the position of "0" is represented by a hatched pixel. When the mask of Figure 5 is applied, diagonal lines appear in the image, as they are composed of the black pixels in Figure 6. In this embodiment, the black pixels in Figure 6 represent pixels recorded with ink, and the pixels with diagonal hatching represent areas where ink is not recorded and the paper remains white. Here, if the mask of Figure 5 is applied only to the B pixel value of RGB, the black pixels in Figure 6 become yellow pixels recorded with Y ink. Also, if the mask of Figure 5 is applied to all pixel values ​​of R, G, and B of RGB, the black pixels in Figure 6 become gray pixels recorded with C ink, M ink, and Y ink, or with K ink.

[0040] Here, pseudocode is shown below that alternately applies the mask in Figure 5(a) and the mask in Figure 5(b) to the entire image (the entire image rendered by S3003). -------------------------------------------------- 01: int i, j, k, l; 02: int width = 600, height=900; 03: unsigned char *data = image data; 04: int **maskA = mask data; 05: bool isMaskA = true; 06: for(j = 0; j < height; j+=8){ 07: for(i = 0; i < width; i+=8){ 08: for(k = 0; k < 8; k++){ 09: for(l = 0; l < 8; l++){ 10: if(isMaskA == true){ 11: data[(i+k)+(j+l)*width] += maskA[k][l]; 12:} 13:} 14:} 15:} 16:} -------------------------------------------------- Thus, embedding information through redundancy can be achieved using the method described above.

[0041] In this embodiment, the above-mentioned document ID is embedded only in the B pixel value of the RGB pixel values ​​in Figure 4. This is because, when recording with ink on the white area of ​​the paper, the Y ink has lower visibility compared to other inks such as C ink, M ink, and K ink. To prevent the embedded information from affecting the original document information, it is preferable that the embedded information be as invisible as possible. Therefore, the B pixel value is modulated to control the fluctuation of the Y ink to the greatest extent possible.

[0042] The document in this embodiment is assumed to have a sufficiently large white area, as shown in Figure 4. In the original document 400 in Figure 4, the white area is the portion excluding object 401, which is the character drawing area, object 402, which is the rectangular drawing area, and object 403, which is the image area. Note that in areas other than the white area, the mask shown in Figure 5 may not adequately embed information. For example, even if the mask in Figure 5 is applied to a solid black area (R=0, G=0, B=0), the processing result will be the same solid black area (R=0, G=0, B=0). In other words, even if the mask is applied, the value will be the same as before the mask was applied, and the information cannot be adequately embedded. Therefore, when embedding information in areas other than the white area, especially in the image area, it is preferable to use a mask like the one shown in Figure 7.

[0043] Figure 7 shows examples of masks applied to the image area. Similar to Figure 5, Figure 7(a) is a mask that creates modulation indicating "0", and Figure 7(b) is a mask that creates modulation indicating "1". In the masks in Figures 7(a) and (b), the pixel values ​​are given variations of -64, 0, and +64. In this case, if all the image data values ​​in the mask area are 0, the values ​​in that area will be -64, 0, and +64, resulting in 0 and +64. Therefore, information can be embedded for all pixel values.

[0044] Figure 8 is a visual representation of the pattern given by the image mask shown in Figure 7. Figure 8(a) corresponds to Figure 7(a), and Figure 8(b) corresponds to Figure 7(b). In Figure 8, the position of "-64" in the mask of Figure 7 is represented by a black pixel, the position of "0" by a diagonal pixel, and the position of "64" by a white pixel. Thus, when the mask of Figure 7 is applied, diagonal lines appear in the multiplexed image as shown in Figures 8(a) and (b).

[0045] In the above example, it was explained that the mask shown in Figure 7 is preferable for object 403 of the image portion of the original document 400 in Figure 4. Generally, for object 401 of the text portion and object 402 of the rectangle drawing portion, it is considered likely that there is a large amount of white space on the paper, so it is preferable to use the mask shown in Figure 5. However, even for the text drawing portion or the rectangle drawing portion, the mask shown in Figure 7 may be preferable depending on the color or thickness of the text. Conversely, even for the image drawing portion, there may be cases where the image is very similar to the white space on the paper. For this reason, in order to achieve more reliable embedding, it may be possible to determine whether the mask shown in Figure 5 or the mask shown in Figure 7 is preferable by obtaining a density histogram in each region and then perform the multiplexing process. In the following explanation, in order to simplify the explanation, it will be explained that the mask shown in Figure 5 is consistently used for embedding the document ID, but the mask shown in Figure 7 may also be used.

[0046] Let's return to the explanation of the flowchart in Figure 3. In S3005, the MFP10 acquires device information. In this embodiment, device information refers to the model name of the recording device that performs the recording, or information related to the printing process, such as the print mode. This is separate from the document ID mentioned above, is information that does not depend on the document content, and is, for example, 256 bits of information.

[0047] Next, in S3006, MFP10 performs a multiplexing process that further superimposes device information onto the multiplexed image (first multiplexed image) generated in S3004. The multiplexing process of device information in S3006 differs from the multiplexing process of document ID in S3004, as it is performed using a pattern for multiplexing device information. The image with the further multiplexed device information is also called the second multiplexed image.

[0048] Figure 9 shows an example of a mask used in the multiplexing process in S3006. In this embodiment, two masks, Figures 9(a) and 9(b), are used to generate "0" and "1" which represent device information. The same method as described in S3004 can be used for image modulation. Multiplexing of the device information is also performed by applying the mask in Figure 9 to the B pixel value.

[0049] Figure 10 is a visual representation of the pattern given by the mask shown in Figure 9. Figure 10(a) corresponds to the mask in Figure 9(a), and Figure 10(b) corresponds to the mask in Figure 9(b). In Figure 10, the position of "-64" in the mask of Figure 9 is represented by a black pixel, and the position of "0" is represented by a diagonal pixel. In the multiplexed image, the presence or absence of dots composed of multiple pixels, as shown in Figure 10, will appear as a modulation result.

[0050] Furthermore, the actual embedding pattern can either be the device information itself, or a pattern that encodes the device information.

[0051] Figure 11 shows an example of embedding a pattern that encodes device information. Figure 11(a) shows the device information encoded in a two-dimensional code. Figure 11(b) shows the embedded pattern in Figure 11(a). A pattern like a two-dimensional barcode, as shown in Figure 11(a), may be recorded using the patterns representing "0" and "1" shown in Figures 10(a) and (b). Figure 11(b) is an image recorded using the pattern representing "1" in Figure 10(b) at the position corresponding to the black pixels of the pattern in Figure 11(a).

[0052] In this way, a multiplexed image (second multiplexed image) with the first and second information embedded is generated. Note that this example describes generating a multiplexed image by multiplexing device information onto an image after the document ID has been multiplexed, but this is not the only method. Alternatively, a multiplexed image may be generated by multiplexing the document ID onto an image after the device information has been multiplexed. Or, the document ID and device information may be multiplexed together.

[0053] Returning to Figure 3, let's continue the explanation. In S3007, the MFP10 performs a generation process to generate a print image. Any known method can be used for the print image generation process. In this embodiment, the print image is generated by the following method. In this embodiment, the following four processes are performed on each pixel of the Bitmap image (second multiplexed image) which is composed of multiplexed RGB pixel values ​​of document ID and device information generated by the multiplexing process in S3006. Color conversion Ink color separation • Output characteristic conversion ·Quantization Here, color conversion is the process of converting the RGB pixel values ​​of the multiplexed Bitmap image so that they can be appropriately recorded by the MFP10. The reason for this is that the colors specified in the drawing commands of a PDL are generally set to color values ​​that can be appropriately represented on a display, and if these values ​​are output directly to a printer, different colors will be output.

[0054] In color conversion, specifically, a three-dimensional lookup table is used to calculate the optimal combination of output pixel values ​​(Rout, Gout, Bout) for each combination of input pixel values ​​(Rin, Gin, Bin). Ideally, since the input values ​​Rin, Gin, and Bin each have 256 gradations, a table Table1

[0256]

[0256]

[0256] [3] is prepared, containing a total of 16,777,216 output value combinations (256 × 256 × 256). Then, Rout = Table1[Rin][Gin][Bin][0] Gout = Table1[Rin][Gin][Bin][1] Bout = Table1[Rin][Gin][Bin][2] This can be achieved by doing so. Alternatively, known techniques for reducing the table size can be used, such as reducing the number of grids in the lookup table from 256 grids to, for example, 16 grids, and determining the output value by interpolating the table values ​​of multiple grids.

[0055] Ink color separation is a process that converts the output values ​​Rout, Gout, and Bout from the color conversion process into the output values ​​of each ink color used in the recording device. In this embodiment, we assume the use of four ink colors: cyan, magenta, yellow, and black. Although there are various ways to implement this conversion, in this embodiment, similar to the color conversion process, a suitable combination of ink color pixel values ​​(C, M, Y, K) is calculated for a given combination of output pixel values ​​(Rout, Gout, Bout). For this calculation, a three-dimensional lookup table Table2

[0256]

[0256]

[0256] [4] is used. C = Table2[Rout][Gout][Bout][0] M = Table2[Rout][Gout][Bout][1] Y = Table2[Rout][Gout][Bout][2] K = Table2[Rout][Gout][Bout][3] This can be achieved by doing so. Alternatively, known techniques for reducing table size may be used.

[0056] Here, in the multiplexing process of S3004, the CMYK pixel values ​​corresponding to the pixel values ​​(R=255, G=255, B=191) obtained by modulating the white paper (R=255, G=255, B=255) using the mask of Figure 5 are preferably the following values. That is, it is preferable that only the Y pixel value is greater than 0. Also, it is preferable that the other CMYK pixel values ​​are close to 0 and smaller than the Y pixel value. The reason for this is that, as explained in the multiplexing process of S3004, we want to reduce the visibility of the embedded image. This is also the case in the result of modulating the white paper using the mask of Figure 9 in S3006.

[0057] Output characteristic conversion is the process of converting the density of each ink color into a recording dot ratio. Specifically, for example, the density of each color with 256 gradations is converted into dot ratios Cout, Mout, Yout, and Kout, each with 1024 gradations. To do this, a one-dimensional lookup table Table3[4]

[0256] is used, which sets the appropriate recording dot ratio for each ink color density. Cout = Table3[0][C] Mout = Table3[1][M] Yout = Table3[2][Y] Kout = Table3[3][K] This can be achieved by doing so. Alternatively, known techniques for reducing the table size can be used, such as reducing the number of grids in the lookup table from 256 grids to, for example, 16 grids, and determining the output value by interpolating the table values ​​of multiple grids.

[0058] Quantization converts the recording dot ratios Cout, Mout, Yout, and Kout for each ink color into values ​​indicating whether each actual pixel's recording dot is On or Off. Any quantization method can be used, such as error diffusion or dithering. Using dithering as an example, Cdot = Halftone[Cout][x][y] Mdot = Halftone[Mout][x][y] Ydot = Halftone[Yout][x][y] Kdot = Halftone[Kout][x][y] By comparing this with a threshold corresponding to each pixel position, the On or Off status of the recording dot for each ink color can be achieved. Here, the occurrence probabilities for each recording dot are Cout / 1023, Mout / 1023, Yout / 1023, and Kout / 1023. In this way, the S3007 print image generation process is completed.

[0059] Next, in S3008, MFP10 performs printing using the print image generated in S3007. By performing this series of processes, a print document with the document ID and device information embedded in the document data can be printed onto the recording paper. This process of generating a print document with the document ID and device information embedded in an image based on a rendering image is also called "multiplex encoding processing".

[0060] Next, we will explain why the information is properly embedded when both the document ID and device information are embedded in the document data. First, looking at the pattern in Figure 6, we can see that the pattern is drawn with diagonal lines of 1px (pixel). Similarly, looking at the pattern in Figure 10, we can see that the pattern is drawn with roughly circular shapes with a diameter of 4px (pixel).

[0061] As can be seen by comparing Figure 6 and Figure 10, the following characteristics are present. Figure 6 shows that the patterns representing "0" and "1" are "approximately equivalent in terms of recording density," and "the direction of the thin lines formed represents the value." Figure 10 shows that while patterns representing "0" and "1" indicate that "higher or lower recording density represents a value," "the formed patterns have no directionality."

[0062] Figure 12 shows the results of multiplexing processing, including the embedding of document IDs in S3004 and the embedding of device information in S3006. Figure 12(a) is an example of a pattern where the document ID is "0" as shown in Figure 6(a) and the device information is "0" as shown in Figure 10(a). Figure 12(b) is an example of a pattern where the document ID is "0" as shown in Figure 6(a) and the device information is "1" as shown in Figure 10(b). Figure 12(c) is an example of a pattern where the document ID is "1" as shown in Figure 6(b) and the device information is "0" as shown in Figure 10(a). Figure 12(d) is an example of a pattern where the document ID is "1" as shown in Figure 6(b) and the device information is "1" as shown in Figure 10(b).

[0063] When comparing Figure 12(a) and Figure 12(b), the relationship that Figure 12(b) has a higher concentration than Figure 12(a) is maintained. Similarly, when comparing Figure 12(c) and Figure 12(d), the relationship that Figure 12(d) has a higher concentration than Figure 12(c) is also maintained. Therefore, the damage to embedded device information caused by the document ID embedding process is reduced.

[0064] Furthermore, when comparing Figure 12(a) and Figure 12(b), the direction of the diagonal lines remains unchanged, from "bottom left to top right." Similarly, when comparing Figure 12(c) and Figure 12(d), the direction of the diagonal lines remains unchanged, from "top left to bottom right." Therefore, the process of embedding device information is able to reduce the likelihood of damaging the document ID embedding.

[0065] Thus, by using the embedding pattern of this embodiment, even when the positions of the patterns embedded in the multiplexing process of S3004 and the multiplexing process of S3006 overlap, it is possible to reduce the loss of embedded information due to interference between the two.

[0066] This reduction in embedded information loss is independent of the type of embedded information. In other words, the process still works even if the embedding patterns for document ID and device information are reversed. Therefore, to rephrase the above, the following information embedding process is being performed. • Primarily, an embedding process in which information is embedded based on the orientation of the shape being recorded (hereinafter also referred to as "shape embedding"). • An embedding process in which information is embedded primarily based on the magnitude of the recorded density (hereinafter also referred to as "density embedding"). By using separate embedding processes for embedding two types of information, it becomes possible to reduce the loss of embedded information that may occur due to interference between the two embedding processes.

[0067] Furthermore, the degree of interference reduction between the two increases when each of the following conditions is met. • Shape embedding unit size > Concentration embedding record size • Density embedding record size > Shape embedding line width In this embodiment, the unit size of the shape embedding is the 8x8 pixel size, which is the mask size (unit area) in Figures 5(a) and (b). In this embodiment, the recording size of the density embedding is the 4x4 pixel size, which is the black pixel size in Figure 10(b). If the unit size of the shape embedding is smaller than the recording size of the density embedding, the density embedding will completely overwrite one pattern of the shape embedding. As a result, the loss of embedded information due to interference between the two will be significant. Similarly, if the recording size of the density embedding is smaller than the line width of the shape embedding (1 pixel width in this embodiment), the shape embedding will completely overwrite one pattern of the density embedding. As a result, the loss of embedded information due to interference between the two will be significant. Therefore, it is preferable to use a pattern that satisfies the above conditions.

[0068] Up to this point, the two types of embedding have been explained using examples where the same color ink is used. However, the ink colors of the objects to be embedded, whether for shape embedding or density embedding, may be different. Using different ink colors can further reduce interference between the two.

[0069] The reason why using different ink colors can reduce interference is explained below. Each ink color used in printing is designed to primarily absorb the following colors. C Ink: Red (R) M Ink: Green (G) Y Ink: Blue (B) K Ink: All Colors (RGB) Therefore, let's consider a case where shape embedding is performed with C ink and density embedding is performed with Y ink. In this case, interference between the embedded information can be reduced by extracting information from the RGB image scanned by the scanner as follows. Extract shape embedding information from R channel information. Extract concentration embedding information from B-channel information. It should be noted that actual inks absorb colors other than those listed above, so interference will not be completely eliminated. However, interference will be reduced compared to using ink of the same color. Therefore, by combining this with the interference reduction effect using the shape embedding and density embedding described above, it is possible to further reduce interference.

[0070] Alternatively, information embedding can be performed using K ink. However, K ink absorbs all colors. Therefore, for example, shape embedding can be performed with K ink and density embedding with Y ink. Then, by extracting information from the RGB image scanned by the scanner as follows, interference between the Y ink used for density embedding and the shape embedding can be reduced. • Extract shape embedding information from the R channel or G channel. Thus, by combining the interference reduction effect using the shape embedding and density embedding described above, it becomes possible to further reduce interference. However, since the K ink used for shape embedding also absorbs blue, it cannot reduce interference with density embedding. In this case, the interference reduction effect using different ink colors cannot be obtained, and the interference reduction effect obtained is obtained by using the shape embedding and density embedding described above.

[0071] It is generally known that using different ink colors can reduce interference between multiple embedding processes. However, if black ink is used in one of the information embedding processes, and the black ink overlaps with other colored inks, it can damage the information recorded by the other colored inks, making it difficult to reduce interference. However, as in this embodiment, by using density embedding and shape embedding in two types of embedding processes, it is possible to reduce the damage to embedded information recorded by other colored inks due to black ink. Therefore, it is possible to obtain an effect of reducing embedded information loss due to interference.

[0072] As can be seen by comparing Figure 12(b) and Figure 6(a), and Figure 12(d) and Figure 6(b), in Figures 6(a) and 6(b), only 2 pixels of the shape embedding overlap with the density embedding pixels out of the 8 pixels used for shape embedding in Figures 6(a) and 6(b). Therefore, when black ink is used for density embedding and yellow ink for shape embedding, the percentage of pixels affected by density embedding in the shape embedding process is reduced to 25% (2 out of 8 pixels).

[0073] Conversely, if shape embedding is done with black ink and density embedding with yellow ink, the percentage of pixels affected by shape embedding in density-embedded pixels can be reduced to 20% (2 out of 12 pixels).

[0074] Furthermore, the above-mentioned interference rate of pixels remains the same even when both shape embedding and density embedding are performed with the same color ink, such as black ink.

[0075] In this embodiment, we have described an example of modulating the B pixel value in the RGB pixel values, but a method of modulating the CMYK pixel values ​​may also be used. In that case, the white of the paper becomes Y=0, M=0, C=0, K=0, and the modulation for the white of the paper must be a positive value. Therefore, the signs of the modulation values ​​shown in Figures 5 and 7 should be reversed. That is, the modulation value of -64 should be reversed to +64, and the modulation value of +64 should be reversed to -64. The same applies to the signs of the modulation values ​​shown in Figure 9.

[0076] Performing modulation on CMYK pixel values ​​offers better control when limiting the ink applied to the paper white to only Y ink. On the other hand, performing modulation on RGB pixel values ​​offers better control when suppressing hue fluctuations when embedding in the image area. Therefore, it is preferable to select a suitable modulation method according to the characteristics of the recording process such as electrophotography or inkjet, as well as the ratio of paper white, characters, and image areas in the document.

[0077] Furthermore, although the modulation value is set to 64 in this embodiment, this is not limited to this. Increasing the modulation value is effective in order to clearly control the dot shape or to align the recording patterns between inkjet recording and electrophotographic recording methods. For example, setting the modulation value to around 255 is effective. Also, if you want to lower the recording density on the paper, you can increase the pattern size, which is 8x8 pixels in this embodiment. Alternatively, the modulation value in Figure 5 may be a pattern that forms a dashed line instead of a solid line. For example, it may be a pattern of "3 pixels with a pixel value of -255, 1 pixel with a pixel value of -0, repeated". It may also be a pattern of "2 pixels with a pixel value of -255, 2 pixels with a pixel value of -0, repeated". Similarly, the modulation value in Figure 9 may be a pattern in which the modulation value is partially missing from Figure 9. For example, it may be a pattern of "1 pixel with 0 for every 4 pixels". It may also be a pattern of "half of the pixels with 0, like a checkerboard pattern". Any combination of these patterns is acceptable. Any pattern that can maintain the following relationship in the two types of embedding processes is acceptable. • Embedding process where information is embedded primarily based on the orientation of the shape being recorded. • Embedding process, where information is embedded primarily based on the level of density being recorded. By embedding patterns that maintain these relationships, it becomes possible to reduce the loss of embedded information due to mutual interference.

[0078] <Information Extraction Processing> Next, we will explain the information extraction process for extracting information from the embedded print document in this manner. As mentioned above, Figure 3(b) is a flowchart of an example of the information extraction process. In the following example, it is assumed that the MFP10 performs the information extraction process, but for example, the processes from the acquisition of the bitmap image in S3102, or the processes from the extraction of device information in S3103, may be performed on the host PC50.

[0079] In S3101, the MFP10 reads a printed document (print original) in which the document ID and device information are multiplexed and encoded. First, the user places the print original in the scanner unit 12 and inputs a reading command. Then, in S3101, the MFP10 performs the document reading process. Specifically, the MFP10 controls the scanner unit 12 to irradiate the original with LED light and converts the reflected light into an analog electrical signal using an image sensor such as a CCD facing each pixel.

[0080] Next, in S3102, the MFP10 digitizes the analog electrical signal obtained in the processing of S3101 to obtain a Bitmap image composed of digital RGB pixel values. Any known method can be used in the Bitmap image acquisition process. In this embodiment, an example using the following method will be described. In this embodiment, the following four processes are performed on each pixel of the Bitmap image composed of RGB pixel values ​​acquired in S3102. MTF correction Input correction • Shading correction Color conversion

[0081] MTF (Modulation Transfer Function) correction is a process that corrects the resolution aspect of the scanner's reading performance. When scanning with the scanner unit 12, the image becomes blurry due to deviations from the focus position and the performance limitations of the lens itself. Therefore, some degree of restoration is performed through filtering by MTF correction. In reality, if the enhancement processing is strong enough to completely restore the image, it can cause overexposure, or exaggerate image noise and dust pixels, making the image detrimental effects more noticeable. Therefore, the design is made to balance image quality improvement with the detrimental effects. To simplify the explanation, the following example shows how to use an edge enhancement filter in MTF correction that multiplies the image center by 5 and multiplies the pixel values ​​on the top, bottom, left, and right by -1. R'[x][y] = R[x][y]×5-R[x-1][y]-R[x+1][y]-R[x][y-1]-R[x][y+1] G'[x][y] = G[x][y]×5-G[x-1][y]-G[x+1][y]-G[x][y-1]-G[x][y+1] B'[x][y] = B[x][y]×5-B[x-1][y]-B[x+1][y]-B[x][y-1]-B[x][y+1]

[0082] Input correction is the process of converting the output value of a CCD, which is originally the amount of photons, into a brightness that matches the sensitivity of the human eye. Specifically, for example, the R'G'B' signals of 4096 gradations for each color are converted into color intensity values ​​R'', G'', B'' of 1024 gradations for each color. This can be achieved by processing as follows using a one-dimensional lookup table Table4[4]

[4096] in which the optimal recording dot ratio for the density of each ink color is set. R” = Table4[0][R'] G” = Table4[1][G'] B” = Table4[2][B'] Furthermore, known techniques for reducing the table size may be used, such as reducing the number of grids in the lookup table from 4096 grids to, for example, 256 grids, and determining the output value by interpolating the table values ​​of multiple grids.

[0083] Shading correction is a process that reduces color unevenness or density unevenness caused by differences in reading sensitivity at each pixel position due to manufacturing variations or assembly variations in the lenses, LEDs, and CCDs that constitute the scanner unit 12. Specifically, for example, the R"G"B" signals of 1024 gradations for each color are converted to color intensity values ​​R"', G"', B"' of 256 gradations for each color. This can be achieved by processing as follows using a one-dimensional lookup table Table5[x][3]

[1024] for density conversion for each X pixel position in the direction in which the scanner lens is positioned (X direction). R"' = Table5[x][0][R"] G"' = Table5[x][1][G"] B"' = Table5[x][2][B"] Furthermore, known techniques for reducing the table size may be used, such as reducing the number of grids in the lookup table from 1024 grids to, for example, 256 grids, and determining the output value by interpolating the table values ​​of multiple grids.

[0084] Next, a color conversion process is performed. Unlike during printing, the color conversion process converts the R''', G''', and B''' values ​​calculated up to this point, which are specific to the scanner device, into Rout, Gout, and Bout values ​​suitable for display on the screen. To do this, similar to the color conversion during printing, a table Table6

[0256]

[0256]

[0256] [3] is prepared, which has a total of 16,777,216 output values ​​(256 x 256 x 256), since the input values ​​R''', G''', and B''' each have 256 gradations. This can then be achieved by processing as follows. Rout = Table6[R”'][G”'][B”'][0] Gout = Table6[R”'][G”'][B”'][1] Bout = Table6[R”'][G”'][B”'][2] Furthermore, known techniques for reducing the table size may be used, such as reducing the number of grids in the lookup table from 256 grids to, for example, 16 grids, and interpolating the table values ​​of multiple grids to determine the output value. By processing in this manner, the bitmap image acquisition process of S3102 is completed.

[0085] Next, in S3103, the MFP10 extracts the multiplexed device information from the bitmap image. The extraction method involves determining which of the patterns shown in Figure 10(a) or (b) is recorded in each 8x8 pixel unit, and extracting either "0" or "1" information. This process is repeated to decode the multiplexed device information. If, in S3006, the device information is embedded in the form of a two-dimensional barcode as shown in Figure 11, then in S3103, the process of decoding the extracted two-dimensional barcode pattern is also performed.

[0086] Next, in S3104, MFP10 determines whether it was able to extract the device information. If the result is Yes, it proceeds to S3105, displays the extracted device information, and then proceeds to S3107. If the result is No, it proceeds to S3106, displays a message indicating "No device information available," and then proceeds to S3107.

[0087] In S3107, MFP10 extracts the multiplexed document ID from the bitmap image acquired in S3102. The extraction method involves determining which of the patterns shown in Figure 6(a) or (b) is recorded in each 8x8 pixel unit, and extracting either "0" or "1" information. By repeating this process, the multiplexed information is decoded.

[0088] Next, in S3108, MFP10 determines whether or not the document ID was extracted. If the result is Yes, the process proceeds to S3109. If the result is No, the process proceeds to S3112, where a message indicating "This is a non-genuine document" is displayed on an external display (not shown), and the process ends.

[0089] If the result is No, there are two possible explanations. Possibility 1: The document scanned by S3101 did not have a document ID embedded in it in the first place. • Possibility 2: The document ID was embedded, but the embedded data could not be read because the printed document was dirty or because significant information had been added later by hand. In the case of possibility 1, you can proceed directly to S3112, but in the case of possibility 2, you may inform the user that "the document ID is embedded, but it is not a genuine document." Doing so will allow the user to recognize the risk that the document may have been tampered with.

[0090] In this embodiment, the determination of possibility 2 is possible in S3107 if 1 bit to 255 bits are extracted from the 256-bit document ID. However, considering the possibility that there might be only one similar image pattern by chance, it is preferable to consider the case as when at least half, 128 bits to 255 bits, are extracted.

[0091] In S3109, MFP10 verifies the extracted document IDs. For example, MFP10 may request verification from host PC50. Host PC50 then requests verification from an external PC via NETWORK I / F507 to confirm whether the extracted document IDs are legitimate. As explained in S3002, by using a blockchain configuration where multiple PCs manage document data and document IDs, the risk of tampering with the document IDs themselves can be reduced. Note that verification with the external PC may be performed by MFP10, or verification may be performed internally within the system between host PC50 and MFP10 without verifying with an external PC.

[0092] Following S3109, in S3110, MFP10 refers to the matching result and determines whether the document ID is authentic. If the result is Yes, it proceeds to S3111. If the result is No, it proceeds to S3112, displays a message indicating that it is an "inauthentic document," and terminates the process.

[0093] Even if the result of S3110 is No, it is acceptable to inform the user that "the document ID is embedded, but it is not a genuine document." This allows the user to recognize the risk that the document may have been tampered with. In S3111, MFP10 displays a message indicating that "it is a genuine document" and terminates the process.

[0094] Next, an example of appropriately extracting the first and second information from a printed document in which the first and second information are embedded will be described. In this embodiment, when extracting the device information in S3103, the accuracy of the extraction can be improved by making a determination using the difference between Figures 10(a) and (b), which is the "level of density".

[0095] Figure 13 shows an example of a filter used when extracting density embedding information. When extracting device information, a 3x3 blur filter as shown in Figure 13 is applied to the Bitmap image read in S3101 and acquired in S3102. As mentioned above, it is preferable to apply it to the image after all MTF correction, input correction, shading correction, and color conversion have been performed, but it may also be applied to the image when some corrections have been completed. In this explanation, each pattern in Figure 12 is used as the read image. In Figure 12, black pixels represent pixels with the maximum density (relative value of 1.0), and diagonal line pixels in Figure 12 represent pixels with the minimum density, which is paper white (relative value of 0.0).

[0096] Figure 14 shows examples of the results of applying the blur filter in Figure 13 to each pattern in Figure 12. Specifically, Figures 14(a) to (d) show examples of applying the blur filter in Figure 13 to Figures 12(a) to (d), respectively. In Figure 14, black pixels represent pixels with a density of 5 / 9 or higher after applying the filter. That is, in Figure 12, they represent pixels where 5 or more of the 9 surrounding pixels, including the pixel of interest, are black pixels. In Figure 14, diagonal pixels represent white pixels. In Figure 14, checkerboard pixels are intermediate between black pixels and diagonal pixels, representing pixels with a density of 1 / 9 or more and 4 / 9 or less after applying the filter. Looking at Figures 14(a) and (c), it can be seen that all the shape-embedded lines have become checkerboard pixels due to the blur filter. Also, looking at Figures 14(b) and (d), it can be seen that the density-embedded pixels have become black pixels. Furthermore, in Figures 14(b) and (d), some of the shape-embedding lines are black pixels. On the other hand, in Figures 14(a) and (c), the pixels of the shape-embedding lines are not as dark as the black pixels in Figures 14(b) and (d). Therefore, Figures 14(a) and (b) can be reliably distinguished from Figures 14(c) and (d).

[0097] On the other hand, when extracting document IDs using S3107, the accuracy of the extraction can be improved by using the "shape orientation," which is the difference between Figure 6(a) and (b), to make the determination.

[0098] Figure 15 shows an example of a filter used when extracting shape embedding information. When extracting the document ID, a 3x3 detection filter as shown in Figure 15 is applied to the Bitmap image read in S3101 and acquired in S3102. As mentioned above, it is preferable to apply it to the image after all MTF correction, input correction, shading correction, and color conversion have been performed, but it may also be applied to the image after some of the corrections have been completed. In this explanation as well, each pattern in Figure 12 will be used as the read image.

[0099] Figure 16 shows examples of the results of applying the filter in Figure 15(a) to each pattern in Figure 12. That is, Figures 16(a) to (d) are examples of applying the filter in Figure 15(a) to Figures 12(a) to (d), respectively. Figure 17 shows examples of the results of applying the filter in Figure 15(b) to each pattern in Figure 12. That is, Figures 17(a) to (d) are examples of applying the filter in Figure 15(b) to Figures 12(a) to (d), respectively. In this embodiment, when extracting document IDs, the filters in Figure 15(a) and Figure 15(b) are applied, respectively.

[0100] In Figure 16, black pixels represent pixels whose density after filtering is 3 / 3, that is, pixels where all three pixels with a coefficient of 1 / 3 are black pixels. In Figure 16, diagonal pixels represent white pixels. Also in Figure 16, checkerboard pixels represent pixels that are intermediate between black pixels and diagonal pixels, with a density after filtering between 1 / 3 and 2 / 3.

[0101] In Figures 16(a) and (b), the shape-embedding lines are all black pixels due to the detection filter in Figure 15(a). Also, some pixels in Figure 16(b) are black pixels due to the effect of density embedding. On the other hand, in Figures 16(c) and (d), almost all pixels of both the shape-embedding lines and the density embedding are checkerboard-patterned pixels.

[0102] Next, looking at Figures 17(a) and (b), both the shape-embedded lines and the density-embedded lines show a checkerboard pattern across almost all pixels due to the detection filter in Figure 15(b). On the other hand, looking at Figures 17(c) and (d), all the shape-embedded lines appear as black pixels. From the above, the following can be concluded. • To reliably extract density embedding information, use a blur filter. To reliably extract shape embedding information, use filters that match the embedded shape. By performing the processing as described above, it is possible to reliably extract two different types of embedded information: device information and document ID.

[0103] Up to this point in this embodiment, we have used two types of embedded information: document ID and device information. However, in this embodiment, we are not limited to these two types of information, and it may be applied to embedding any information. Examples of the first and second types of information are listed below. First information Second information • Encrypted document ID, encrypted password • Document ID: External PC information for document ID verification. Document ID User Information • Encrypted device information and encrypted password The first and second pieces of information mentioned above can be embedded either by concentration or by shape.

[0104] Furthermore, in this embodiment, for the sake of ease of understanding, an example in which concentration embedding and shape embedding are performed with the same pattern size has been described, but this embodiment is not limited to the same pattern size. As mentioned above, the size of the pattern itself may be different as long as the following conditions are met. • Shape embedding unit size > Concentration embedding record size • Density embedding record size > Shape embedding line width

[0105] Furthermore, although this embodiment describes an example in which information embedding is performed on the MFP10, the information embedding may also be performed on the host PC50. By performing the information embedding on the host PC50, it becomes possible to create a print document with multiplexed information using an MFP or printer that does not support information embedding.

[0106] Alternatively, the host PC 50 may generate a separate image for multiplexing from the original image, send both the multiplexing image and the original image from the host PC 50 to the MFP 10, and then combine them in the MFP 10.

[0107] Alternatively, the embedding process for the first information may be performed on the host PC 50, and the embedding process for the second information may be performed on the MFP 10. This is an efficient process under the following conditions.

[0108] Document IDs, etc., are managed on the host PC or an external PC. • Equipment information is managed by MFP10. In this embodiment, while the information extraction process is described as being performed on the MFP10, the information extraction process may also be performed on the host PC50. By performing the information extraction process on the host PC50, it becomes possible to extract information from print documents read using an MFP that does not support information extraction.

[0109] Alternatively, the extraction of the first information may be performed on the host PC 50, and the extraction of the second information may be performed on the MFP 10. This is an efficient process under the following conditions. Document IDs, etc., are managed on the host PC or an external PC. • Equipment information is managed by MFP10.

[0110] Furthermore, the information embedding and information extraction processes performed on the host PC 50 may be carried out on an external PC or other device via the NETWORK I / F 507 shown in Figure 1. An example is shown below.

[0111] Example 1: In S3004 in Figure 3, the host PC 50 sends a multiplexing processing request to an external device (external PC) and sends the document ID and document data to the external PC. The external PC sends the multiplexed information (multiplexed image) with the document ID multiplexed to the host PC 50.

[0112] Example 2: In S3107 in Figure 3, the host PC 50 sends an extraction processing request to the external PC and sends the scanned document data to the external PC. The external PC extracts the document ID from the scanned document data and sends the document ID to the host PC 50.

[0113] Similarly, the embedding of device information in S3006 and the extraction of device information in S3103 in Figure 3 can also be requested from an external PC. By requesting part of the series of processes from an external PC in this way, the processing load on the host PC 50 and MFP 10 can be reduced.

[0114] Furthermore, in this embodiment, a pattern matching process was described as an example of the extraction process for shape-embedded information. However, the extraction method is not limited to this process, and extraction may be performed using various methods, such as performing spatial frequency analysis and determining whether or not there are peaks at a specific frequency and in a specific direction. Any form is acceptable as long as the concentration-embedded shape does not have a strong peak in a specific direction, and the shape-embedded shape has a peak in a specific direction. By setting the concentration-embedded shape not to have a strong peak in a specific direction and the shape-embedded shape to have a peak in a specific direction, shape-embedded information can be extracted stably even when concentration-embedded and shape-embedded are superimposed.

[0115] As described above, according to this embodiment, multiple types of information can be embedded in a print document without using a special configuration.

[0116] <<Second Embodiment>> In the first embodiment, examples were described of embedding information using shape embedding and density embedding, and of extracting the embedded information. In this embodiment, a form further combined with watermark printing will be described. Watermark printing is a technique that enables visual identification during copying for the purpose of deterring forgery of forms or receipts. More specifically, watermark printing is a technique that clearly indicates that a document is a copy by having a latent image area and a background area that appear to be the same density during printing, but are copied with different densities during copying. The latent image area is the area that is printed even during copying, and the background area is the area that is not printed during copying.

[0117] When both background printing and embedding are applied to the same area on the recording paper, there is a risk that when the printed original is copied, the information embedded in the background area will be printed as well, reducing the density difference between the latent image area of ​​the background printing and the background area. This may result in a deterioration of visual readability.

[0118] This embodiment describes an example in which the deterioration of visual readability due to the background printing is reduced even when both background printing and the two types of information embedding processes described in the first embodiment are performed. The basic device configuration is the same as in the example described in the first embodiment, so the differences will be explained in detail.

[0119] Figure 18 is a flowchart illustrating the embedding process of document ID, device information, and watermark information in this embodiment. Similar to the example described in Figure 3, the process in Figure 3 is described as being performed by the MFP10, but all of the processes shown in Figure 18 may be performed by the host PC50. Some of the processes shown in Figure 18 may be performed by the host PC50, and the other processes may be performed by the MFP10.

[0120] The processes from S18001 to S18003 are the same as those from S3001 to S3003 in Figure 3, so their explanation is omitted.

[0121] In S18004, MFP10 acquires watermark area information. Watermark area information indicates which areas of the original document will become the latent image area and which areas will become the background area when printing watermarks.

[0122] Figure 19 shows an example of background pattern area information. In Figure 19, area 1900 represents the entire area of ​​the original document. The size of area 1900 is the same as the original document 400 in Figure 4, and each pixel in Figure 19 corresponds one-to-one with each pixel in Figure 4. When printing, the image in Figure 19 and the image in Figure 4 are printed superimposed. The background pattern area information in Figure 19 may not be printed in the areas where the image in Figure 4 is located, or it may be printed in the areas where the image in Figure 4 is located. Each pixel in Figure 19 has one of two values, 0 or 1, where 0 represents the background area and 1 represents the latent image area. In Figure 19, the hatched area represents the latent image area 1901, and the white area represents the background area 1902. In other words, the area where "Background Printing" is written in white is the background area 1902. When the background area 1902 is scanned or copied, its density decreases, resulting in an output that is close to white paper. On the other hand, the latent image region 1901 experiences less density reduction than the background region when scanned and copied, resulting in a relatively darker output compared to the background region. For example, if text such as "Copying Prohibited" is printed as a background pattern, the text will become visible when the document is copied, allowing for distinction between the original and the copy.

[0123] Specifically, when printing a background pattern, the latent image area contains many pixels recorded in a continuous sequence of multiple recording pixels. Conversely, the background area contains many pixels that are not continuous and are recorded as single pixels. In other words, in the background area, the number of pixels recorded adjacent to a recorded pixel is less than the number of pixels recorded adjacent to a recorded pixel in the latent image area. During printing, the latent image area 1901 and the background area 1902 are designed to be printed at approximately the same density. By designing it this way, when scanning or copying, the density of pixels composed of single pixels in the background area is read at a very low density, while the density of pixels recorded in a continuous sequence in the latent image area is read at a sufficiently high density. As a result, when scanning a printed original with a background pattern, the following relationship is achieved. Latent image density > Background area density

[0124] Let's continue explaining the process shown in Figure 18. In S18005, the MFP10 performs multiplexing of the watermark and document ID. That is, the MFP10 generates a multiplexed image that combines the watermark printing process and the document ID embedding process. Here, the document ID obtained in S18002 and the watermark area information obtained in S18004 are used to perform multiplexing on the rendering image generated in S18003. This is to allow the copier to extract the document ID from the scanned original when the output of the multiplexed image is copied using a copier, while also ensuring that the effect of the watermark printing is optimally realized. In other words, it allows the copier to determine whether the output itself is based on a digital document managed by a document ID, and to visually determine whether it is a copy.

[0125] In this embodiment, the document ID is embedded in the latent image area. Here, in the explanation of Figure 19, an example was described in which the background area 1902 in Figure 19 is the text area, but this is not the only example. In general, in pattern printing, the background area may be the text area, or conversely, the latent image area may be the text area, and either form can be implemented. However, in this embodiment, the background area is used as the text area because, when considering the area ratio of the background area to the latent image area in relation to the entire page, the latent image area occupies a larger area. In other words, when embedding information in the embedding process, a larger occupied area means that more area can be embedded. Therefore, the amount of data that can be embedded can be increased. Furthermore, if the area of ​​the text area is sufficiently widened by increasing the font size of the characters, the text area may be used as the latent image area. In other words, the area with the larger occupied area between the text area and the non-text area should be used as the latent image area.

[0126] Figure 20 is a flowchart detailing the multiplexing process of the background pattern and document ID in S18005. In S20001, a pixel loop process is initiated, sequentially processing one pixel at a time from the top-left pixel to the bottom-right pixel of the image rendered in S18003. Note that the order of pixel processing is not limited to this; any unprocessed pixels should be processed sequentially. Hereafter, the pixels targeted for processing in the loop process will be referred to as the "pixel of interest."

[0127] In S20002, MFP10 checks the background area information acquired in S18004 corresponding to the pixel of interest and determines whether the pixel of interest belongs to the latent image area of ​​the background. If the result is YES, the process proceeds to S20003. If the result is NO, the pixel of interest belongs to the background area, and the process proceeds to S20004.

[0128] In S20003, MFP10 performs the process of embedding the document ID for the pixel of interest. Figure 21 is a diagram showing the mask used for the multiplexing process of the background pattern and document ID. In S20003, depending on whether the embedded data is "0" or "1", either the pattern in Figure 21(a) or Figure 21(b) is embedded. In this S20003, the document ID pattern is embedded in the area that should be the latent image area. Once the embedding is complete, the process proceeds to S20005.

[0129] In S20004, MFP10 embeds a background pattern. Here, the embedding is done using the pattern shown in Figure 21(c), independently of the embedded document ID data. Once the embedding is complete, the process proceeds to S20005.

[0130] In S20005, MFP10 determines whether processing of all pixels has been completed. In this example, the pixel of interest starts from the top left and moves one pixel to the right after processing one pixel, and when processing of the rightmost pixel is completed, it moves to the pixel one pixel below the leftmost pixel. Therefore, when processing of the rightmost and bottommost pixel is completed, all pixels are finished. If the result of the determination is Yes, processing ends and the process proceeds to S18006 in Figure 18. If the result of the determination is No, the process proceeds to S20001, and processing continues with the next unprocessed pixel as the pixel of interest.

[0131] Here, the details of the information embedding shown in Figures 21(a), (b), and (c) performed in S20003 and S20004 follow the same procedure as the embedding process described in S2004 of Figure 3 in the first embodiment, so the explanation is omitted.

[0132] Figure 22 is a visual representation of the pattern given by the mask described in Figure 21. Figures 22(a) to (c) correspond to Figures 21(a) to (c), respectively. In Figure 22, the position of "-64" in the mask of Figure 21 is represented by a black pixel, and the position of "0" is represented by a diagonal pixel. In the latent image region to which the masks of Figures 21(a) and (b) are applied, diagonal lines appear as shown in Figures 22(a) and (b). In this embodiment, the black pixels in Figure 22 represent pixels recorded with ink, and the diagonal pixels represent pixels that are not recorded with ink and remain white. If the mask of Figure 21 is applied only to the B pixel value of RGB, the black pixels in Figure 22 become yellow pixels recorded with Y ink. Also, if the mask of Figure 21 is applied to all pixel values ​​of R, G, and B of RGB, the black pixels in Figure 21 become gray pixels recorded with C ink, M ink, and Y ink, or K ink.

[0133] Similarly, by adding the contents of the mask in Figure 21(c) to the background image, a discrete pattern can be applied to an 8px x 8px area within the background image. Figure 22(c) visually illustrates the pattern applied to the image by the mask in Figure 21(c). In Figure 22(c), the position "-64" in the mask in Figure 21(c) is represented by a black pixel, and the position "0" is represented by a diagonal pixel. A discrete dot arrangement like that shown in Figure 22(c) will appear in the background image.

[0134] Here, we will explain the surface characteristics of each background print in Figures 21(a), (b), and (c). The three patterns in Figures 21(a), (b), and (c) each consist of 8 pixels of "-64" and 56 pixels of "0" within an 8px x 8px area. Therefore, when these three patterns are embedded in the white area of ​​the paper, the three patterns will be recorded on the paper surface at almost the same density during printing. Each pattern is recorded so as not to overlap on the paper surface. Because the density during printing is almost the same, when the original print manuscript is printed, it will be output in a way that makes it difficult for the user to distinguish between them.

[0135] In Figure 22(c), the recording pattern is different from the patterns in Figures 22(a) and (b) in that each dot is further apart from the other dots. As a result, the image blurring when scanned causes the density to be read as lower. Consequently, when copied, this area becomes a background area that is not printed. On the other hand, in Figures 22(a) and (b), each dot has at least two adjacent dots, so the density reduction when scanned is less than in Figure 22(c). Consequently, when copied, this area becomes a latent image area that is printed.

[0136] Here, the difference in density reduction during scanning between Figures 22(a) and (b) and Figure 22(c) is similar to that of general background printing. However, the point to note in this embodiment is that the degree of density reduction during scanner reading between Figure 22(a) and Figure 22(b) is almost the same. In other words, by configuring the latent image region in background printing with Figure 22(a) or Figure 22(b), the following effects can be achieved. • By not embedding information in the background area of ​​the watermark print, it is possible to print in a way that does not hinder the reduction in density of the background area during scanning. • The latent image area of ​​the background print can be constructed with nearly the same density. • It is possible to embed information in the latent image region. • Information embedded as a latent image can be maintained even during scanning.

[0137] In this embodiment, the number of pixels with the modulation value "-64" in Figure 21(c) is the same as in Figures 21(a) and (b), but it is not necessary to have the same number of pixels. It is sufficient to make the density of each pattern recorded on the paper similar. Therefore, the number of pixels with the modulation value "-64", the modulation value, etc. may be increased or decreased according to the recording characteristics of the recording device. Alternatively, in order to make the density of each pattern similar, the pattern shapes and density values ​​in Figures 21(a) and (b) may be modulated in reverse.

[0138] Following S18005, S18006 performs the process of acquiring device information. However, this process is the same as S3005 in Figure 3, so its explanation is omitted. Similarly, the processes from S18007 to S18009 are the same as the processes from S3006 to S3008 in Figure 3, so their explanation is also omitted.

[0139] With the above, it is possible to print a document on recording paper in which the document ID is embedded in the latent image area of ​​the document data, and equipment information is embedded in the entire page, including the background area. It is also possible to embed the equipment information only in the latent image area excluding the background area. However, in that case, a difference in density will occur between the latent image area and the background area in the printed document, which may reduce the functionality as a background pattern. For this reason, it is preferable to embed the equipment information in the entire area, including the background area. The information extraction process in this embodiment is the same as the process described in Figure 3(b), so the explanation is omitted here.

[0140] In this embodiment, the visibility of the watermark print is ensured by not embedding embedded information (first information, document ID) in the background area of ​​the watermark print. As a result, embedded information corresponding to the background area of ​​the watermark print may be lost. It is preferable to address this point as follows. Table 1 shows an example of suitably performing watermark printing, embedding, and extraction processing on the blank areas of the original document.

[0141] [Table 1] Table 1: Examples of processes to reduce the impact of background areas in pattern printing.

[0142] Examples 1 to 3 in Table 1 are explained in detail below. All of them are examples of embedding information in the latent image region.

[0143] Example 1 involves an embedding process that embeds information while avoiding the background area, and an extraction process that extracts the embedded information while avoiding the background area. In other words, it is an example of suppressing the loss of embedded information due to the presence of a background area in pattern printing.

[0144] In the embedding process in Example 1, for example, in S20001 in Figure 20, the loop is performed in 8px x 8px processing units rather than in 1-pixel units. Also, in step S20002, a determination is made in 8px x 8px processing units whether or not it is a latent image area of ​​the background pattern. As a result of this processing, if the area of ​​interest is a latent image area, the process proceeds to S20003, where information can be embedded without loss by sequentially embedding 1 bit at a time into the area of ​​interest that is a latent image area. In other words, embedding is performed while determining whether or not it is a latent image area, so that the embedding information is embedded only in the latent image area.

[0145] On the other hand, in the extraction process of Example 1, for example, at S3107 in Figure 3, a determination is made as to whether or not it is blank in 8px x 8px units. If it is not blank, the embedded information is extracted; if it is blank, the embedded information is not extracted.

[0146] Example 2 illustrates how to compensate for missing embedded information due to the presence of a background area in a watermark print by embedding the same information in multiple areas. In the embedding process in Example 2, the same information is embedded multiple times in the latent area. In addition, the extraction process in Example 2 involves supplementing the information from multiple extraction results.

[0147] Figure 23 illustrates the multiple embedding locations in Example 2. The symbols 2300-2302 in Figure 23 correspond to symbols 1900-1902 in Figure 19, so their explanation is omitted. The areas 2311-2316 demarcated by dashed lines in Figure 23 are the areas containing the embedding regions, and the same embedding information is performed for each of these regions 2311-2316. Each of the regions 2311-2316 is the same size.

[0148] Here, each region 2311-2316 is 128px x 128px, so 16 x 16 embedding masks as shown in Figure 21 can be embedded, and 256 bits of information can be embedded in each region. Specifically, in the embedding process of Example 2, for example, in the pixel loop S20001 in Figure 20, a 256-bit document ID is embedded in the latent image regions of each region 2311-2316 in Figure 23. Embedding 256 bits of embedding information results in the size of region 2311, for example. However, in reality, the embedding information is embedded only in the latent image region and not in the background region. Therefore, information that should be embedded in the background region is missing. Here, as can be seen in Figure 23, regions 2311 and 2312 have a background region below them, so the embedding information on the lower side is missing. Similarly, in regions 2313 and 2314, the embedding information on the upper and lower sides is missing. Furthermore, the upper embedding information is missing in regions 2315 and 2316.

[0149] On the other hand, in the extraction process of Example 2, for example, in S3107 in Figure 3, the embedded information is extracted multiple times, and the parts that can be extracted in each extraction process are combined to generate a 256-bit document ID. Taking the print original in Figure 23 as an example, information can be extracted from the latent image regions (latent image parts) within regions 2311 to 2316. As mentioned above, since the parts that can be extracted as latent images differ in each region, it is possible to extract the entire document ID by combining them. Specifically, the extracted information from the upper regions of regions 2311 and 2312, the extracted information from the central regions of regions 2313 and 2314, and the extracted information from the lower regions of regions 2315 and 2316 are combined. This makes it possible to reconstruct and extract the document ID from the embedded information in all regions.

[0150] Example 3 is an example of allocating the latent image area necessary to embed 256 bits of document ID information. In the embedding process of Example 3, the process of allocating a latent image area of ​​the required size is performed. In the extraction process of Example 3, the process of extracting from the allocating area is performed.

[0151] In the embedding process of Example 3, for example, the background area information acquired in S18004 in Figure 18 is used to reserve a latent image area for the number of pixels to which 256 bits can be embedded. Specifically, 1 bit is embedded in 8px x 8px units, so if there is an area of ​​128px x 128px, it is possible to embed 256 bits. The position of the reserved latent area can be determined by setting a predetermined area in the background area information in Figure 19 beforehand, or by detecting a non-background area (i.e., latent area) of a predetermined size. In this case, it is preferable to embed a predetermined mark pattern to serve as a marker during extraction.

[0152] On the other hand, in the extraction process of Example 3, the extraction process is performed from the reserved latent image region. The information of the reserved latent image region may be determined by setting a predetermined region in the background region information in Figure 19, or by detecting and determining the location where a predetermined landmark pattern is embedded.

[0153] Alternatively, the processes described in Examples 1 to 3 above can be combined. By doing so, it is possible to suppress the loss of embedded information due to the presence of a background area in the watermark printing.

[0154] As described above, according to this embodiment, even when both pattern printing and two types of information embedding processes are performed, the deterioration of visual readability can be reduced.

[0155] <<Other Embodiments>> In the embodiments described above, an MFP10 having both recording and reading means was used as an example, but the invention is not limited to this. A printer having recording means and a scanner having reading means may also be used. That is, the recording process described above may be performed by a printer that is an SFP (Single Function Printer), and the reading process may be performed by a scanner different from this printer. Furthermore, even in the form using the MFP10, the recording process and the reading process may be performed by separate devices.

[0156] Furthermore, while the examples described show that the information embedded in the multiplexing process consists of first and second information, the types of information may be increased as long as they remain legible. In other words, the information embedded in the multiplexing process of the above-described embodiment may consist of multiple types of information.

[0157] Furthermore, in the examples described above, the embedding process involved embedding the document ID before embedding the device information, and the extraction process involved extracting the device information before extracting the document ID, but this order is not limited to this. Similarly, in the embedding process, the example described involved performing the shape embedding process followed by the density embedding process, and in the extraction process, the example described involved extracting the density embedding information before extracting the shape embedding information, but this order is not limited to this.

[0158] The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

Claims

1. The first acquisition method for obtaining the original image, A second acquisition means for acquiring a first multiplexed image in which first information is embedded in the original image by a first method in which the shape of the pattern changes, A third acquisition means for acquiring a second multiplexed image in which a second type of second information different from the first information is embedded in the first multiplexed image by a second method in which the density of the pattern changes, A control means for performing control to output print data for a print original using the second multiplexed image, Equipped with, The second acquisition means is, Further region information is obtained that indicates a first region that is read relatively darker when scanning a printed document, and a second region that is read relatively lighter than the first region. The first information is embedded in the original image by switching and embedding multiple patterns in which the shape of the pattern changes within the first region. A first multiplexed image is obtained in which a pattern is embedded in the second region in which the number of pixels recorded in adjacent pixels is less than that in the first region. The control means performs control to output the print data using the second multiplexed image. An image processing apparatus characterized by the following:

2. The image processing apparatus according to claim 1, characterized in that the unit size of the recording pattern formed in the first method is larger than the recording size of the recording pattern formed in the second method.

3. The image processing apparatus according to claim 1 or 2, characterized in that the width of the recording pattern formed in the first method is smaller than the width of the recording pattern formed in the second method.

4. The image processing apparatus according to any one of claims 1 to 3, characterized in that, in the first method, the density of the pattern representing the first value and the density of the pattern representing the second value are equal.

5. The image processing apparatus according to any one of claims 1 to 4, characterized in that the color to which the first method is applied and the color to which the second method is applied are different.

6. The image processing apparatus according to claim 5, wherein the original image is an image composed of RGB pixel values, the first method is applied to all of the RGB pixel values, and the second method is applied to the B pixel value among the RGB pixel values.

7. The image processing apparatus according to claim 5, wherein the original image is an image composed of RGB pixel values, the first method is applied to the B pixel value among the RGB pixel values, and the second method is applied to all of the RGB pixel values.

8. The image processing apparatus according to claim 5, wherein the original image is an image composed of CMYK pixel values, the first method is applied to the K pixel value among the CMYK pixel values, and the second method is applied to the Y pixel value or the K pixel value among the CMYK pixel values.

9. The image processing apparatus according to any one of claims 1 to 4, characterized in that the color to which the first method is applied and the color to which the second method is applied are the same.

10. The image processing apparatus according to claim 9, wherein the original image is an image composed of RGB pixel values, and the first method and the second method are applied to the B pixel value among the RGB pixel values.

11. The image processing apparatus according to claim 9, wherein the original image is an image composed of CMYK pixel values, and the first method and the second method are applied to the Y pixel value or the K pixel value among the CMYK pixel values.

12. The system further comprises a first embedding means that performs embedding according to the first method described above, The image processing apparatus according to any one of claims 1 to 11, characterized in that the second acquisition means acquires the first multiplexed image in which the first information is embedded in the original image by the first embedding means.

13. The image processing apparatus according to any one of claims 1 to 11, characterized in that the second acquisition means transmits a multiplexing processing request including the original image acquired by the first acquisition means to an external device, and in response to the multiplexing processing request, the external device receives and acquires the first multiplexed image in which the first information is embedded in the original image by the first method.

14. The system further comprises a second embedding means for embedding using the second method described above, The image processing apparatus according to any one of claims 1 to 13, characterized in that the third acquisition means acquires the second multiplexed image in which the second information is embedded in the first multiplexed image by the second embedding means.

15. The image processing apparatus according to any one of claims 1 to 14, characterized in that the density of a unit region of the pattern embedded in the first region is equal among the plurality of patterns.

16. The image processing apparatus according to any one of claims 1 to 15, characterized in that the density of a unit region of the pattern embedded in the second region is equal to the density of a unit region of the pattern embedded in the first region.

17. The image processing apparatus according to any one of claims 1 to 16, characterized in that the image processing apparatus comprises printing means for printing the print data.

18. An acquisition means for acquiring image data obtained by reading a printed image in which first information is embedded by a first method in which the shape of the pattern changes, and second information of a different type from the first information is embedded by a second method in which the density of the pattern changes, Extraction means for extracting the first information and the second information from the image data, Equipped with, The acquisition means is, The image data obtained is a printed original document comprising a first region that is read relatively darker when read, and a second region that is read relatively lighter than the first region, wherein the first information is embedded in the printed image by switching and embedding a plurality of directional patterns in the first region, and the second region has a pattern in which the number of pixels recorded in adjacent pixels is less than that in the first region. The extraction means extracts the first information from the first region. An image processing apparatus characterized by the following:

19. The image processing apparatus according to claim 18, characterized in that the extraction means extracts the first information by applying a filter that emphasizes the shape of the pattern to the image data.

20. The image processing apparatus according to claim 18 or 19, characterized in that the extraction means extracts the second information by applying a blur filter to the image data.

21. The image processing apparatus according to any one of claims 18 to 20, characterized in that the extraction means transmits an extraction processing request including image data acquired by the acquisition means to an external device, and extracts the first information by receiving the first information extracted by the external device in response to the extraction processing request.

22. The first acquisition process involves obtaining the original image, A second acquisition step involves acquiring a first multiplexed image in which first information is embedded in the original image by a first method in which the shape of the pattern changes, A third acquisition step involves acquiring a second multiplexed image in which a second type of second information different from the first information is embedded in the first multiplexed image using a second method in which the density of the pattern changes, A control step that controls the output of print data for a print original using the second multiplexed image, It has, The aforementioned second acquisition process is, Further region information is obtained that indicates a first region that is read relatively darker when scanning a printed document, and a second region that is read relatively lighter than the first region. The first information is embedded in the original image by switching and embedding multiple patterns in which the shape of the pattern changes within the first region. A first multiplexed image is obtained in which a pattern is embedded in the second region in which the number of pixels recorded in adjacent pixels is less than that in the first region. The control step involves performing control to output the print data using the second multiplexed image. An image processing method characterized by the following:

23. An acquisition step of acquiring image data by reading a printed image in which first information is embedded by a first method in which the shape of the pattern changes, and second information of a different type from the first information is embedded by a second method in which the density of the pattern changes, An extraction step of extracting the first information and the second information from the image data, It has, The acquisition process described above is: The image data obtained is a printed original document comprising a first region that is read relatively darker when read, and a second region that is read relatively lighter than the first region, wherein the first information is embedded in the printed image by switching and embedding a plurality of directional patterns in the first region, and the second region has a pattern in which the number of pixels recorded in adjacent pixels is less than that in the first region. The extraction step involves extracting the first information from the first region. An image processing method characterized by the following:

Images