JP2007166333A - Apparatus and method for processing image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus where erroneous detection cannot occur easily in information buried in background. <P>SOLUTION: A composite machine 1 includes an image development means 2 for entering a document image; a background pattern image generation means 10 for generating a background pattern image including a code image in which a plurality of kinds of codes indicating reproduction inhibition are arranged according to prescribed rules; an image composite means 11 for compositing the document image and the background pattern one; and a print means 12 for providing an output of the composited image composited by the image composite means 11, thus aligning the reproduction inhibition codes regularly for determining whether the reproduction inhibition code is true later by using a regular arrangement method, and hence preventing the erroneous detection when there is a pattern that is similar to a minute slash pattern in a general document to be copied and increasing precision in information detection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image processing apparatus and an image processing method capable of preventing information leakage of confidential documents.

  In recent years, with the spread of personal computers, printers, and copying machines, there has been a problem of information leakage due to unauthorized copying of confidential documents printed out. As a conventional technology for preventing and suppressing unauthorized copying of confidential documents, when printing confidential documents, copy prohibition information is embedded in the image and then printed out, and when copying, the original is read and embedded in the image. Multifunction devices having an illegal copy prohibition function are being studied, such as detecting copy prohibition information being detected and stopping normal copy operations when copy prohibition information is included (see, for example, Patent Document 1). ).

  Further, the illegal copy prohibition function has been developed, and two types of copy prohibition information in an image and copy permission condition information (for example, a personal identification number) for permitting copying under a specific condition when a confidential document is printed. Information is embedded and printed out, and at the time of copying, two types of information, copy-prohibited information and copy-permitted condition information, embedded in the image are detected from the scanned image to determine whether the copy-permitted condition is met. A multifunction device having an advanced illegal copy prohibition function is also considered, in which the copy operation is stopped when the copy permission condition is not met, but the copy operation is performed when the copy permission condition is met. Here, as an embedding method of copy prohibition information / copy permission condition information, for example, the following method has been proposed (for example, see Patent Document 2).

  That is, a background copy-forgery-inhibited pattern image having a comparatively low density is synthesized with a minute pattern on the entire background of the document image. The background copy-forgery-inhibited pattern image is composed of two regions, a latent image character region and a background region, and each region is composed of different micropatterns. The latent image character area is composed of a relatively small dot pattern, and the background area is composed of an array of two kinds of minute oblique line patterns. The two types of diagonal lines represent bits 0 and 1, respectively, and two-dimensional code images in which the two types of diagonal patterns are two-dimensional arrays of a predetermined size are repeatedly arranged adjacent to each other in the background portion. It has become. The copy permission condition information is embedded in this two-dimensional code.

As copy prohibition information, a special code (copy prohibition code) that consists entirely of a hatched pattern corresponding to bit 0 inside the two-dimensional array, or a special code that consists entirely of a hatched pattern corresponding to bit 1 inside the two-dimensional array Embed by code. As another conventional example for preventing unauthorized copying of confidential documents, when printing confidential documents, information related to the user who performed the printing, date / time information, etc. are embedded and printed out. An image processing apparatus that analyzes a user, a client PC, a printer, and a date and time embedded in an image that has been read and read to identify an information leakage source has been studied. This function can be configured as an additional function of the conventional multifunction peripheral.
JP 2003-280469 A JP 2003-283790 A

  However, in the technique described in Patent Document 2, whether or not the code is a copy prohibition code is detected based on the number and ratio of two types of minute oblique line patterns in the block. Therefore, if the original document image sent to the printer has an image area with a very small pattern similar to the copy prohibition code, the original on which the document has been printed out is combined with the copy prohibition code. In spite of this, there is a problem that the copy machine may erroneously detect that it is a copy-prohibited document, and may not be able to be copied despite being a general document that is not a confidential document.

  Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide an image processing apparatus and an image processing method with less erroneous detection of information embedded in the background.

  In order to solve the above-described problem, an image processing apparatus according to the present invention includes an image input unit that inputs a document image and a background tint block image that generates a background tint block image including a code image in which a plurality of types of codes are arranged according to a predetermined rule. A generating unit; an image combining unit that combines the document image and the code image; and an image output unit that outputs the combined image combined by the image combining unit. According to the present invention, by arranging the codes regularly, it is possible to determine later whether the code is really a code or not by using a regular arrangement method. Thereby, even when a general document to be copied contains a pattern similar to a minute oblique line pattern, erroneous detection can be prevented and the accuracy of information detection can be improved.

  The background pattern image generating means is arranged so that the plurality of types of codes are alternately arranged in the horizontal and vertical directions.

  An image processing apparatus according to the present invention includes an image reading unit that reads an image, an image output unit that outputs the read image, and a block that is a part of a plurality of types of codes from the image read by the image reading unit. A code block detecting means for detecting; an arrangement determining means for determining whether or not the blocks detected by the code block detecting means are arranged according to a predetermined rule; and the image reading means based on a determination result by the arrangement determining means Restriction determining means for determining a restriction on the image read by the control means, and control means for controlling the image output by the image output means based on the determination result by the restriction determining means. According to the present invention, since the arrangement of codes has regularity, it is determined by using this regularity whether or not the code is really a stop code. Thereby, even when a general document to be copied contains a pattern similar to a minute oblique line pattern, erroneous detection can be prevented and the accuracy of information detection can be improved.

  The restriction determination means is an image read by the image reading means when code blocks of the same type are linearly arranged at predetermined intervals and different types of code blocks are linearly arranged at predetermined intervals in the vertical direction. It is determined that there is a restriction on

  The restriction determination unit is configured not to perform restriction determination on the image based on the same type of blocks continuously arranged when the same type of code blocks are continuously arranged for a predetermined number of blocks or more. . The code is a code indicating copy prohibition, and the restriction on the image is copy prohibition.

  The image processing method of the present invention includes an image input step for inputting a document image, a code image generation step for generating a background tint block image including a code image in which a plurality of types of codes are arranged according to a predetermined rule, the document image, An image synthesizing step for synthesizing the background tint block image; and an image output step for outputting the synthesized image. According to the present invention, it is possible to determine later whether or not it is really a code by using a regular arrangement method of codes. Thereby, even when a general document to be copied contains a pattern similar to a minute oblique line pattern, erroneous detection can be prevented and the accuracy of information detection can be improved. In the background tint block image generation step, the plurality of types of codes are arranged alternately in the horizontal and vertical directions.

  The image processing method of the present invention includes an image reading step for reading an image, an image output step for outputting the read image, and a block that is part of a plurality of types of codes from the image read in the image reading step. A detection step to detect, an array determination step to determine whether or not the blocks detected in the detection step are arrayed according to a predetermined rule, and the image reading step to read based on the determination result in the array determination step A restriction determination step for determining a restriction on the image; and a control step for controlling image output by the image output step based on a determination result by the restriction determination step. According to the present invention, since the arrangement of codes has regularity, it is determined using this regularity whether or not the code is really a code. Thereby, even when a general document to be copied contains a pattern similar to a minute oblique line pattern, erroneous detection can be prevented and the accuracy of information detection can be improved.

  The restriction determination step is read by the image reading step when the same type of code blocks are linearly arranged at a predetermined interval and different types of code blocks are linearly arranged at a predetermined interval in the vertical direction. It is determined that there is a restriction on the image. In the restriction determination step, when the same type of code blocks are continuously arranged more than a predetermined number of blocks, the restriction determination for the image is not performed based on the continuously arranged same type of blocks. .

  According to the present invention, it is possible to provide an image processing apparatus and an image processing method with less erroneous detection of information embedded in the background.

  Hereinafter, the best mode for carrying out the present invention will be described. FIG. 1 is a block diagram of a multifunction machine according to a first embodiment of the present invention. The multifunction device 1 as an image processing apparatus has a plurality of functions such as a print function, a copy function, and a scan function. The multi-function device 1 is connected to a client PC (personal computer) connected to a network such as a LAN (Local Area Network). As shown in FIG. 1, the multifunction machine 1 includes an image expansion unit 2, an image storage unit 3, a reading unit 4, a scanned image processing unit 5, a prohibited code detection unit 6, a digital code decoding unit 7, a user interface unit 8, and a control. Means 9, background tint block image generation means 10, image composition means 11, and printing means 12 as image output means.

  The image expansion means 2 generates document image data by performing drawing processing of print data (hereinafter referred to as “PDL data”) described in a print description language (PDL) input via the LAN, and draws the drawing. The document image data is stored in the image storage means 3. The image storage means 3 stores document image data and background copy-forgery-inhibited pattern image data. The reading unit 4 reads a document placed on the platen and outputs the read image data to the scanned image processing unit 5. A document image is input from the image expanding unit 2 or the image reading unit 4. The scanned image processing unit 5 performs image processing such as image correction, color conversion, and enlargement / reduction on the read image, and stores the image in the image storage unit 3.

  The prohibition code detection means 6 detects the prohibition code from the image read by the reading means 4. The digital code decoding means 7 decodes the digital code from the image read by the reading means 4. The user interface means 8 has an input / output device such as a touch panel display, and is a part that receives various operations and input of embedded information from the user.

  The control unit 9 controls the entire multifunction device 1 and performs various controls based on the detection results from the prohibition code detection unit 6 and the digital code decoding unit 7. The control means 9 encodes the fixed information, job information, and page unit information as a fixed information code, job information code, and page information code, respectively. The fixed information includes a machine identification ID of the MFP, a network address (IP address, MAC address), and the like. The job information includes a job identification ID, a transmission source PC network address, a user ID, an output start date and time, a total number of pages, and the like. The page information includes a page number and the like. The part information is information on some of the copies.

  The background copy-forgery-inhibited pattern image generation means 10 generates a background copy-forgery-inhibited pattern image including a code image in which a plurality of types of codes indicating copy prohibition are arranged according to a predetermined rule. The background copy-forgery-inhibited pattern image generation means 10 arranges a plurality of types of codes so as to alternate in the horizontal and vertical directions. The image synthesizing unit 11 synthesizes the document image and the background pattern image. The printing unit 12 prints and records the combined image data synthesized by the image synthesizing unit 11 on a sheet and outputs it.

  Next, background tint block image generation processing will be described. FIG. 2 is a schematic diagram for explaining the code. FIG. 3 is a schematic diagram for explaining the pattern number arrangement. The operation of the background tint block image generation means 10 will be described. Additional information (copy prohibition information, condition information, latent image information) is input from the control unit 9 to the background tint block image generation unit 10. The background tint block image generation means 10 generates a latent image based on the input latent image information. The latent image information is information indicating what kind of latent image character is embedded in the pattern image.Specifically, the latent image character string, font type, font size, and latent image character string direction ( Angle) and other information. The background copy-forgery-inhibited pattern image generation means 10 draws a latent image character string in the specified direction with the specified font type and font size, and generates a latent image image as a binary latent image image.

  Here, the resolution of the latent image is a resolution obtained by dividing the resolution of the printer by the size of a pattern to be described later. For example, when the printer resolution is 600 dpi and the pattern size is 12 pixels × 12 pixels, the resolution of the latent image is 50 dpi. The background copy-forgery-inhibited pattern image generation means 10 encodes the input copy prohibition information and condition information.

  First, when the copy prohibition information indicates that the document that has been printed out is not to be copied by the copying machine, two types of copy prohibition codes shown in FIGS. 2A and 2B are generated. Here, the copy prohibition code in FIG. 2 (A) has a bit 0 in the entire code, and the copy prohibition code in FIG. is there. When copy prohibition information is not input or when it does not indicate that a document that has been printed out is not to be copied by a copying machine, the two types of codes shown in FIGS. 2A and 2B are generated. Not done.

  Next, when condition information is input, an error correction code is applied to the condition information to generate a digital code as shown in FIG. The code in FIG. 2C represents a bit string of encoded condition information by the arrangement of bit 0 and bit 1. The outer periphery of the cord has a special bit pattern for facilitating the positioning of the cord. Next, a plurality of the generated codes are repeatedly arranged as shown in FIG. 3A to generate a pattern number array having the same size as the size of the latent image. Here, the hatched rectangle in FIG. 2 is the copy prohibition code in FIG. 2A, the vertical hatched rectangle is the copy prohibition code in FIG. 2B, and the dot hatched rectangle is in FIG. 2C. It has become a digital code.

  If a copy prohibition code is not generated, a digital code is placed in the copy prohibition code portion in the figure. If a digital code is not generated, a copy prohibition code is placed in the digital code portion in the figure. At this time, the value of each element of the pattern number array is 0 or 1. Next, referring to the latent image, the pattern number of the element of the pattern number array corresponding to the coordinates of the black pixels in the latent image is changed to 2. If this is performed for all the black pixels in the latent image, the pattern number arrangement is such that the latent image characters are drawn with the pattern number 2 on the background where the copy prohibition code and the digital code are arranged side by side. This state is shown in FIG. A black “COPY” portion in the figure indicates a portion in which the pattern array number is changed to “2”. This pattern number array is output to the background tint block image generation means 10.

  The background copy-forgery-inhibited pattern image generation unit 10 refers to each element of the input pattern number array, reads a pattern corresponding to the pattern number from the pattern storage unit, and converts it into a pattern image, thereby generating a background copy-forgery-inhibited pattern image. The generated background tint block image is stored in the image storage means 3.

  4A and 4B are schematic diagrams showing examples of patterns stored in the pattern storage unit. FIG. 4A is a pattern corresponding to pattern number 0, FIG. 4B is a pattern corresponding to pattern number 1, and FIG. 4C is a pattern number. 2 is a pattern corresponding to 2. Here, the pattern number array corresponds to the resolution of the image obtained by dividing the printer resolution by the pattern size, and the pattern image generated based on this is generated by replacing one element of the pattern number array with one pattern. Therefore, the generated pattern image matches the resolution of the printer. Also, the pattern image is an image in which the latent image character is converted into an isolated dot pattern by converting it into a hatched pattern corresponding to the bit value of the copy prohibition code and digital code.

  The pattern image generated in this way is stored in the image storage means 3 as a background tint block image, is synthesized with the document image data, and is printed out on paper. FIG. 5 is a schematic diagram illustrating an example of print output and copy output. An example of a printed image is shown in FIG. 5A (for convenience of explanation, the document image shows an example of a pure white image having no image elements). FIG. 5C is an enlarged view of the area surrounded by the rectangle in FIG. FIG. 5B shows a copy output image when FIG. 5A is copied by a copying machine.

  Next, the operation during copying will be described. FIG. 9 is an operation flowchart during copying. The user places a document on the platen and presses the copy button to start copying (step S11). The reading unit 4 reads a document (step S12). The scanned image processing unit 5 performs image processing (image correction, color conversion, enlargement / reduction, etc.) on the read image and stores the image in the image storage unit 3. The read image is input to the prohibition code detection unit 6 and the digital code decoding unit 7, and the prohibition code detection process and the digital code decoding process are performed (step S13).

  If the prohibited code is detected by the prohibited code detection means 6 (“Y” in step S14) and the digital code decoding means 7 detects the digital code and succeeds in decoding (“Y” in step S15), the control means 9 suspends the copying operation and allows the user to input a personal identification number from the user interface means 6. If the input code number and the code number included in the decoded data match (“Y” in step S16), the copy operation for that page of the document is continued (step S17). If the code numbers do not match (“N” in step S16), or if the digital code decoding means cannot detect the digital code (“N” in step S15), the control means 9 sends the user interface means 8 to the user interface means 8 A message to the effect is displayed and the copying operation is stopped (step S18).

  Next, the prohibition code detection means 6 will be specifically described. FIG. 6 is a diagram showing the configuration of the prohibition code detection means 6. As shown in FIG. 6, the prohibition code detection means 6 includes a binarization processing unit 61, a noise removal processing unit 62, a pattern detection unit 63, a blocking unit 64, a number calculation unit 65, a ratio calculation unit 66, and a prohibition determination unit. 67. Here, the block size of the blocking unit 64 is smaller than the code size. The block size is determined so that one or more blocks are completely included in each code in the read image even when there is a skew when the document is read by the reading unit 4.

  FIG. 7 is a layout diagram of codes. As shown in FIG. 7, a copy prohibition code T1 in which the code is all bit 0 and a copy prohibition code T2 in which the code is all bit 1 are arranged every other code, and a digital code D is arranged in the empty portion. ing. FIG. 8 is a diagram for explaining the relationship between the prohibition code, the read image, and the block. Reference numeral 70 is a read image read by the reading means 4, 71 is a block in the read image, 72 is a code boundary in the read image when there is image skew, and 731 to 734 are prohibition codes by the prohibition determination unit 67. Blocks in which 0 is detected and 741 to 750 indicate blocks in which the prohibition determination unit 67 has detected the prohibition code 1.

Referring to FIG. 8, the prohibited code block has the following regularity.
-Forbid code blocks of the same type are continuously detected only for a predetermined number of blocks or less. Here, the predetermined number is the number of code size pixels / the number of block size pixels. For example, two or more blocks with prohibition codes 1 and 0 are not detected in succession.
The same type of prohibited code blocks are arranged linearly at a predetermined interval, and different types of prohibited code blocks are arranged linearly at a predetermined interval in the vertical direction. For example, the blocks 731 and 732 of the prohibition code 0 are arranged in a straight line at a predetermined interval, and different types of blocks 749 and 750 of the prohibition code 1 are arranged in a straight line at a predetermined interval in the vertical direction.

  For this reason, the prohibition determination unit 67 uses the reading means 4 when the same type of prohibited code blocks are arranged in a straight line at a predetermined interval and different types of prohibited code blocks are arranged in a straight line at a predetermined interval in the vertical direction. It is determined that the read image is copy-prohibited. Further, the prohibition determination unit 67 determines that it is a false detection when the same type of prohibition code blocks are continuously arranged more than a predetermined number of blocks, and copies based on the same type of prohibition blocks continuously arranged. Do not make prohibition decisions.

  Next, the operation of the prohibition code detection means 6 will be described. FIG. 10 is an operation flowchart of the prohibition code detection means 6. When the image data output from the reading unit 4 is full color, grayscale conversion is performed. The binarization processing unit 61 binarizes the read image (step S21). The noise removing unit 62 removes noise from the binarized image (step S22). Specifically, the noise removing unit 62 examines the size of a black pixel block (pixel block) in the image, and removes a pixel block having a size equal to or smaller than the first threshold as isolated dot noise. Further, the noise removing unit 62 removes a pixel block having a size equal to or larger than the second threshold as a character or the like in the document that is not a hatched pattern.

  The pattern detection unit 63 performs pattern matching of two types of oblique line patterns indicating bits 0 and 1, and detects a position and a bit value (step S23). Specifically, the pattern shown in FIGS. 4A and 4B is applied at the position of each pixel in the image data, and detection is performed by template matching. Here, when the pattern (A) is detected, the pixel value 0 is output, when the pattern (B) is detected, the pixel value 1 is output, and when the pattern is not detected, the pixel value 2 is output. The image data output from the pattern detection unit 63 is input to the blocking unit 64.

  The blocking unit 64 divides the input image data into blocks of a predetermined size, the number calculation unit 65 calculates the number of bits 0 and the number of bits 1 for each block, and the ratio calculation unit 66 sets the bits for each block. A ratio of 0 is obtained, and the result is input to the prohibition determination unit 67 (step S24). Here, the block size is set to a size smaller than half of the size of the copy prohibition code and the digital code, and is set to such a size that one or more blocks are completely included in the code. The prohibition determination unit 67 determines whether the prohibition code is 0, the prohibition code 1, or any other number based on the number and ratio of bits 0 and 1 in units of blocks (step S25).

  The prohibition determination unit 67 determines whether the blocks detected by the blocking unit 64 are arranged according to a predetermined rule. Next, the prohibition determination unit 67 determines whether or not the read image read by the reading unit 4 is copy-prohibited based on the determination result of the block arrangement rule determination. Specifically, for each block, the prohibition determination unit 67 determines whether the prohibition code 0 block, the consecutive number of the prohibition code 1 block, and the same type of prohibition code blocks are arranged in a straight line at predetermined intervals, or in the vertical direction. It is checked whether different types of prohibited code blocks are arranged at predetermined intervals (step S26).

  The prohibition determination unit 67 determines that the block is a correct prohibition code block when these conditions are satisfied. The prohibition determination unit 67 counts the number of correct prohibition code blocks for each prohibition code 0 and prohibition code 1 (step S27). If both count values exceed the threshold value, the prohibition determination unit 67 determines that the read image is a prohibition image, and notifies the control unit 9 of the result (step S28). The control unit 9 controls image output based on the determination result by the prohibition determination unit 67.

  According to the above embodiment, since the arrangement of the prohibition code and the digital code has regularity, the prohibition code is detected for each block, the pattern of arrangement of the detected prohibition code block is recognized, and whether or not it is really the prohibition code. By determining whether or not a general document to be copied has a pattern similar to a minute oblique line pattern, it is possible to prevent erroneous detection and improve information detection accuracy.

  Note that the image processing method of the present invention is realized by the multifunction device 1. The multi-function device 1 is realized using, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The image processing method of the present invention can be realized as a program executed by controlling a computer. This program can be provided by being stored and distributed in a magnetic disk, an optical disk, a semiconductor memory, or other recording media, or distributed via a network.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications, within the scope of the gist of the present invention described in the claims, It can be changed. In particular, the above embodiment has been described based on the code arrangement example of FIG. 7, but it is also possible to arrange the codes according to other predetermined rules. In that case, the prohibition determination means is set to determine the consecutive number of blocks and the prohibition code block arrangement rule in accordance with the code arrangement rule. In the above embodiment, the copy prohibition code is used as the code. However, in the present invention, the code is not limited to the copy prohibition code. When the code is not limited to the copy prohibition code, the prohibition determination unit 67 may determine the restriction on the image read by the reading unit 4.

1 is a block diagram of an image processing system according to a first embodiment of the present invention. It is a schematic diagram explaining a code | cord | chord. It is a schematic diagram explaining a pattern number arrangement | sequence. It is a schematic diagram which shows the example of a pattern. It is a schematic diagram which shows the example of a print output and a copy output. It is a figure which shows the structure of a prohibition code detection means. FIG. It is a figure explaining the relationship between a prohibition code, a read image, and a block. It is an operation | movement flowchart at the time of copying. It is an operation | movement flowchart of a prohibition code detection means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multifunction machine 2 Image expansion means 3 Image storage means 4 Reading means 5 Scan image processing means 6 Prohibition code detection means 7 Digital code decoding means 8 User interface means 9 Control means 10 Background tint block image generation means 11 Image composition means 12 Printing means

Claims (11)

An image input means for inputting a document image;
A background copy-forgery-inhibited pattern image generating means for generating a background copy-forgery-inhibited pattern image including a code image in which a plurality of types of codes are arranged according to a predetermined rule;
Image synthesizing means for synthesizing the document image and the code image;
Image output means for outputting a synthesized image synthesized by the image synthesizing means;
An image processing apparatus comprising: The image processing apparatus according to claim 1, wherein the background tint block image generation unit arranges the plurality of types of codes so as to alternate in a horizontal and vertical direction. Image reading means for reading an image;
Image output means for outputting the read image;
Code block detection means for detecting blocks that are part of a plurality of types of codes from the image read by the image reading means;
An array determining means for determining whether or not the blocks detected by the code block detecting means are arrayed according to a predetermined rule;
A restriction determination unit that determines a restriction on an image read by the image reading unit based on a determination result by the arrangement determination unit;
An image processing apparatus comprising: control means for controlling image output by the image output means based on a determination result by the restriction determination means. The restriction determination means is an image read by the image reading means when code blocks of the same type are linearly arranged at predetermined intervals and different types of code blocks are linearly arranged at predetermined intervals in the vertical direction. The image processing apparatus according to claim 3, wherein the image processing apparatus determines that there is a limitation on the image processing apparatus. The restriction determination means does not perform restriction determination on the image based on the same type of blocks continuously arranged when the same type of code blocks are continuously arranged more than a predetermined number of blocks. The image processing apparatus according to claim 3 or 4. The code is a code indicating copy prohibition,
6. The image processing apparatus according to claim 1, wherein the restriction on the image is copy prohibition. An image input step for inputting a document image;
A code image generation step for generating a background tint block image including a code image in which a plurality of types of codes are arranged according to a predetermined rule;
An image synthesis step of synthesizing the document image and the background copy-forgery-inhibited pattern image;
An image output step of outputting the composite image;
An image processing method comprising: The image processing method according to claim 7, wherein in the background tint block image generation step, the plurality of types of codes are arranged alternately in a horizontal and vertical direction. An image reading step for reading an image;
An image output step for outputting the read image;
A detection step of detecting a block that is part of a plurality of types of codes from the image read in the image reading step;
An array determining step for determining whether or not the blocks detected in the detecting step are arrayed according to a predetermined rule;
A restriction determination step for determining a restriction on the image read in the image reading step based on a determination result in the arrangement determination step;
And a control step for controlling image output by the image output step based on a determination result by the restriction determination step. The restriction determination step is read by the image reading step when the same type of code blocks are linearly arranged at a predetermined interval and different types of code blocks are linearly arranged at a predetermined interval in the vertical direction. The image processing method according to claim 9, wherein it is determined that there is a restriction on the image. In the restriction determination step, when the same type of code blocks are continuously arranged more than a predetermined number of blocks, the restriction determination for the image is not performed based on the same type of blocks arranged continuously. The image processing method according to claim 9 or 10.

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