JP2006060805A - Method and apparatus for image generation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for generating an image, adding image data which prevents tampering by duplication when generating an image using a document data of which tampering by duplication is inhibited, and enables easy tracing of a distribution route of an output print. <P>SOLUTION: When a PDL data of a secret document, to which additional information is added, is input to a print data input section 1, a document image generator 2 generates a document image data. An additional information extractor 4 extracts the additional information constituted of a string of latent image characters and coded information. A latent image generator 5 generates an image data of the latent image characters from the string of the latent image characters, and an additional information coder 6 encodes the coded information into an error-correction code, and generates a code data by referencing the image data of the latent image characters. A pattern image generator 8 generates a pattern image from a dot pattern stored in a pattern storage 7, using the code data. An image synthesizer 10 carries out synthesis by superposing together the document information data and the pattern image, and in an image forming section 11, the document image data having the pattern image synthesized therein is printed out. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image generation method and an image generation apparatus, and more particularly to an image generation method and an image generation apparatus that generate an image based on document data that is prohibited from being counterfeited by copying.

  With the recent spread of personal computers and higher performance of printers and copiers, unauthorized copying and unauthorized use of confidential documents such as family register copies and contracts have become a problem.

  Conventionally, special paper called copy forgery prevention paper has been used to suppress such illegal copying and unauthorized use of confidential documents. The copy forgery prevention paper is a paper on which a special pattern is printed in advance, which is hard to be seen by human eyes, but emerges with warning characters that are hidden when copied by a copying machine. When a document printed on this copy-forgery prevention paper is copied with a copying machine, warning characters such as “copy prohibited” will stand out prominently on the copied material. In addition to deterrence, it is possible to distinguish between original and compound by warning characters.

  A digital recording apparatus described in Japanese Patent Laid-Open No. 7-231384 generates a latent image embedded image in which a latent image to be visualized by copying is embedded in a background image by image processing, similar to the copy forgery prevention paper described above. It is. In this apparatus, when image data read by a CCD is copied and recorded, the latent image embedded image in which the latent image character portion and the background portion are subjected to dithering processing having different specific densities is superimposed on the main image. By combining them, it is possible to obtain the same print as when using copy forgery prevention paper using normal paper.

  However, it is not possible to take measures such as identifying a person who has performed an illegal act and preventing a recurrence only by raising a warning character or the like. For this reason, in order to suppress unauthorized copying and unauthorized use of confidential documents, it is particularly important to add information that can trace the outflow route of confidential documents to the printed image, such as which printer was used for output. Become.

  Such information can be embedded as a latent image in a background image by using a digital recording apparatus described in Japanese Patent Application Laid-Open No. 7-231384. However, when the latent image embedded in the background image is visualized by copying, it cannot be visualized unless the characters embedded as the latent image are large to some extent. For this reason, the length of the character string to be embedded is limited, and there is a problem that a large amount of information cannot be embedded in one image. In addition, it is not suitable for embedding information such as privacy-related information that is not desired to be exposed to human eyes under normal use. That is, there is a problem that information to be embedded is limited to information that can be visualized, and information necessary to reliably specify the outflow route of the confidential document cannot be added.

  Japanese Laid-Open Patent Publication No. 10-285385 proposes a recording medium output method for embedding information such as an IP address of a printer device and a print date and time in an image to be printed out using a dot pattern that is difficult to visually identify. . Since information such as an IP address is embedded in an image printed out using this method, the output printer device and the output date and time can be specified by analyzing the information. Further, since information such as an IP address is added by a dot pattern that is difficult to visually identify, the image quality of the printed image is not impaired.

  However, in the method described in Japanese Patent Laid-Open No. 10-285385, a dot pattern is formed using yellow toner in order to make it difficult to identify visually, so this method cannot be applied to a monochrome printer. There is a problem of lack of versatility. When a printed image is copied with a black and white copying machine, the dot pattern formed using yellow toner is not copied, so it is easy to delete the added information and it is difficult to trace the outflow route. There is a problem of becoming.

  Furthermore, although unauthorized copying and unauthorized use of confidential documents can be suppressed using the method and apparatus described above, unauthorized copying and unauthorized use cannot be reliably prevented. In order to prevent unauthorized copying and unauthorized use, it is necessary to recognize that the material to be copied in the copying machine is a confidential document that is prohibited from being copied, and to provide the copying machine with a function for prohibiting copying. is there.

  However, it is difficult for the copying machine to recognize a dot pattern or the like embedded in the image as a latent image. If a machine-readable code such as a barcode is added to the image and printed out, the copier can recognize it as a confidential document, but the position of the barcode in the printed out image can be determined. Since it can be clearly discriminated, there is a problem that information added by copying without bar codes can be easily deleted.

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to distribute the output print when an image is generated based on document data that is prohibited to be forged by copying. It is an object of the present invention to provide an image generation method and an image generation apparatus capable of adding copy forgery prevention image data that can be easily traced. Another object of the present invention is to add anti-counterfeit image data that can take measures to prohibit copying of the printed output when generating an image based on document data that is prohibited from forgery by copying. It is an object of the present invention to provide an image generation method and an image generation apparatus capable of performing the above.

  In order to achieve the above object, an image generation method according to claim 1 is an image generation method for generating an image based on document data prohibited from forgery by copying, and based on predetermined information, A copy forgery prevention image data in which a machine readable code is provided in either one of the latent image portion and the background portion is generated, and the generated copy forgery prevention image data and the document data are combined, and based on the combined data An image is generated.

  In the image generation method according to claim 1, copy forgery prevention image data in which a machine readable code is provided in either one of the latent image portion and the background portion is generated based on predetermined information. Since the code is not easily deciphered by humans, various information can be embedded in the copy forgery prevention image data, and the outflow path of the output print can be easily traced.

  In addition, since this machine-readable code can be easily read by a machine, for example, it has a function of recognizing that a material to be copied in a copying machine is a document that is prohibited from being copied and prohibiting a copying operation. It is possible to take measures to prohibit copying of the output print, such as by providing it in a copying machine.

  In addition, since copy forgery prevention image data and document data forbidden forgery by copying are combined and an image is generated based on the combined data, copy forgery prevention paper can be used without using copy forgery prevention paper. The same effect as used can be obtained.

  In the above image generation method, the machine readable code is preferably copied by a copying machine, and the latent image is embedded using the machine readable code copied by the copying machine and the image not copied by the copying machine. Copy forgery prevention image data can be formed. For example, when a machine-readable code is provided in the latent image portion, an image that is not copied by a copying machine is provided in the background portion to constitute copy forgery prevention image data. When the output print is copied by the copying machine in this case, the background portion is whitened and the latent image portion is copied at a high density so that the latent image is visualized. When a machine-readable code is provided in the background portion, an image that cannot be copied by a copying machine can be provided in the latent image portion to constitute copy forgery prevention image data. When the output print is copied by a copying machine in this case, the latent image portion is whitened and the background portion is copied at a high density, and the latent image is visualized.

  Further, the predetermined information may include at least one of coded information and latent image information for generating a machine-readable code, and may be input in addition to document data. The generated machine-readable code is preferably composed of a plurality of patterns having substantially the same area and different shapes. By adding the coded information and latent image information to the document data and inputting them, the coded information and latent image information can be changed according to the document data, and the output print out path can be traced. It can be made easier.

  According to a fourth aspect of the present invention, there is provided an image generation apparatus that applies the image generation method of the first aspect to an image generation apparatus, and generates an image based on document data that is prohibited from being counterfeited by copying. An input unit for inputting predetermined information, and generation for generating copy forgery prevention image data in which machine readable code is provided in either one of the latent image portion and the background portion based on the input information And means for synthesizing the generated copy forgery prevention image data and document data.

  In the image generation apparatus, the generation unit can generate the copy forgery-preventing image data after performing an error correction encoding process of the information. By performing the error correction coding process of information, the decoding process of the copy forgery prevention image data including the machine readable pattern is facilitated.

  The generation unit may include an arrangement control unit that controls the machine-readable code to be arranged in either the latent image portion or the background portion. By providing such an arrangement control means, it is possible to arbitrarily select which of the latent image portion and the background portion is to be visualized and diversify the copy forgery prevention image data.

  The image generation method and the image generation apparatus of the present invention use copy forgery prevention paper without using copy forgery prevention paper when generating an image based on document data prohibited from forgery by copying. There is an effect that the same effect can be obtained.

  In addition, when an image is generated based on document data prohibited from forgery by copying, it is possible to add copy forgery-preventing image data that can easily trace the distribution route of the output print. .

  In addition, when generating an image based on document data that is prohibited from being counterfeited by copying, it is possible to add copy forgery preventing image data that can take measures to prohibit copying the output print. There is an effect.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram showing a first embodiment of an image generating apparatus according to the present invention. As shown in FIG. 1, the image generation apparatus includes a print data input unit 1, a document image generation unit 2, a document image buffer 3, an additional information extraction unit 4, a latent image generation unit 5, an additional information encoding unit 6, and a pattern. The storage unit 7, the pattern image generation unit 8, the pattern image buffer 9, the image composition unit 10, and the image formation unit (output device) 11 are configured.

  Document data (PDL data) described in PDL (Printer Description Language) transmitted from an external computer or the like is input to the print data input unit 1. The header of this PDL data is set to the IP (Internet Protocol) address of the computer that sent the print job, the user name that sent the print job, the name of the document file to be printed, the time stamp of the document to be printed, and the document file Encoding information such as a secret level, a password set in the document file, and a latent image character string embedded as a latent image are added as additional information. Such additional information is added only to confidential documents and the like that need to be prohibited from being copied.

  The document image generation unit 2 rasterizes the PDL data and generates document image data converted into a binary image. The document image buffer 3 temporarily stores the document image data generated by the document image generation unit 2.

  The additional information extraction unit 4 extracts additional information added to the header portion of the PDL data from the PDL data input to the print data input unit 1, and converts the extracted additional information into a latent image character string and coded information. Decompose. The latent image generation unit 5 reads a latent image character string, rasterizes the read latent image character string, and generates latent image character image data converted into a binary image. The additional information encoding unit 6 performs error correction encoding on the encoded information input from the additional information extraction unit 4 and performs error correction encoding with reference to the latent image character image data input from the latent image generation unit 5. Code conversion is performed on the encoded information to generate code data.

  The pattern storage unit 7 stores three types of dot patterns shown in FIG. The three types of dot patterns will be described later. The pattern image generation unit 8 selects a dot pattern corresponding to each value of the code data from the three types of dot patterns stored in the pattern storage unit 7 and generates a pattern image composed of the three types of dot patterns. The pattern image buffer 9 temporarily stores the pattern image generated by the pattern image generation unit 8.

  The image composition unit 10 superimposes and combines the pattern image read from the pattern image buffer 9 on the document image data read from the document image buffer 3.

  The image forming unit 11 prints out document image data in which pattern images are combined. In other words, the image forming unit 11 is configured by a printer equipped with a printer engine such as a xerographic engine and that records document image data on paper.

  Next, the operation of the image generation apparatus according to the first embodiment will be described.

  When PDL data transmitted from an external computer or the like is input to the print data input unit 1, the input PDL data is interpreted and raster-developed by the document image generation unit 2, and converted into binary image data. Is stored in the document image buffer 3.

  Further, additional information added to the header portion of the PDL data is extracted by the additional information extraction unit 4. When the additional information is not extracted from the PDL data, a signal (not shown) indicating that the additional information is not extracted from the additional information extracting unit 4 is sent to the latent image generating unit 5 and the additional information encoding unit. 6 is transmitted to the pattern image generation unit 8 and the image composition unit 10. Processing in each unit that receives this signal is not performed, and the document image data read from the document image buffer 3 passes through the image composition unit 10 and is output to the image forming unit 11 as it is.

  When additional information is extracted from PDL data, the extracted additional information is decomposed into a latent image character string and coded information by the additional information extraction unit 4. Among these, the latent image character string is output to the latent image generation unit 5, and the encoded information is output to the additional information encoding unit 6.

  When a latent image character string is input to the latent image generation unit 5, the input latent image character string is raster-developed using a predetermined font, and binary imaged latent image character image data is generated. . The font to be used is set with a relatively large number of points (for example, 48 points) in order to exhibit the same effect as the copy forgery prevention paper described above. However, the latent image character image is converted into a binary image so as to satisfy the relationship of the following expressions (1) and (2).

Latent image character image resolution = printer resolution ÷ number of horizontal pixels of the pattern (1)
Number of vertical and horizontal pixels of latent image character image
= Number of vertical and horizontal pixels in the document image ÷ Number of horizontal pixels in the pattern (2)
For example, if the printer resolution is 600 dpi, the pattern has 12 horizontal pixels, and the document image data has vertical and horizontal pixels of 4960 × 7015 pixels, the resolution of the latent image character image is 50 dpi and the vertical and horizontal pixels are 413 × 584 pixels. That is, one pixel of the latent image character image is set so as to correspond to the size of one pattern. The latent image character image data generated by the latent image generation unit 5 is output to the additional information encoding unit 6.

  When the encoded information is input to the additional information encoding unit 6 from the additional information extracting unit 4 and the latent image character image data is input from the latent image generating unit 5, the input encoded information is converted into the additional information encoding unit. 6 is error correction encoded. The encoded information subjected to error correction coding is represented by a bit string of “0” and “1”. The bit string is read bit by bit, and the read bit string is converted into a two-dimensional array (unit two-dimensional unit) of a predetermined size. Sort by (array). The outermost peripheral bits of the unit two-dimensional array are all bits 1 in order to facilitate the positioning and extraction of the code data.

  The unit two-dimensional array is further repeatedly arranged in the vertical direction and the horizontal direction to form a two-dimensional array having a size corresponding to the number of pixels of the latent image character image. Thereafter, when the pixel of the latent image character image data is referred to and the pixel of the latent image character image data is a black pixel, the value of the element of the two-dimensional array corresponding to the position of the black pixel is forcibly copied. Is replaced with a value “2” for selecting a pattern that is difficult to reproduce. As described above, the code data (two-dimensional array data) that has been subjected to error correction coding, rearranged into a two-dimensional array, and code-converted according to the latent image character image data is output to the pattern image generation unit 8.

  Next, when the two-dimensional array data is input to the pattern image generation unit 8, one pattern is selected from the pattern storage unit 7 in accordance with the value of each element of the input two-dimensional array data, and the selected pattern is selected. Is read. For example, if the element value is “0”, the pattern 0 shown in FIG. 2A is selected. If the element value is “1”, the pattern 1 shown in FIG. If the value is “2”, the pattern 2 shown in FIG. 2C is selected. Each read pattern is written at a corresponding position in the pattern image buffer 9.

  By repeating the above processing for all the two-dimensional array data having a size corresponding to the number of pixels of the latent image character image, the pattern image buffer 9 is composed of the three types of patterns and has the same size as the document image data. Pattern image data is formed and stored.

  In the image composition unit 10, when the document image data is read from the document image buffer 3 and the pattern image is read from the pattern image buffer 9, the pixels of both image data are synthesized by a logical sum operation, and the pattern image is synthesized. The document image data is output to the image forming unit 11.

  The image forming unit 11 prints out document image data combined with a pattern image on a sheet by a printer engine provided inside the image forming unit 11.

  An example of a document image printed out as described above is shown in FIG. In this example, a white document image is synthesized on the entire surface so that the latent image portion is clear.

  FIG. 3A shows the entire document image printed out. The area of the character “COPY” in FIG. 3A is a latent image portion that emerges when copied by a copying machine, and the surrounding area is a background portion. In this figure, although the character “COPY” can be identified, the character “COPY” in the latent image portion is actually difficult to identify.

  FIG. 3C is an image obtained by enlarging the area surrounded by the square in FIG. 3A. The document image printed out is composed of patterns 0 to 2, and the latent image portion includes Pattern 2 is arranged, and pattern 0 or 1 is arranged in the background portion.

  The patterns 0 to 2 have different shapes as described above, but the number of black pixels constituting each pattern is substantially the same, and the density when printed out is the same regardless of the pattern arrangement. Has been. Actually, even if the number of pixels is the same due to the printer characteristics, the density differs slightly depending on the pattern. Therefore, the number of black pixels and the pattern shape are set so that the density after print output matches exactly. Yes.

The patterns 0 and 1 arranged in the background portion are linear fine patterns as shown in FIGS. 2A and 2B, and have a characteristic that the patterns are reproduced when copied by a copying machine. ing. On the other hand, pattern 2 arranged inside the latent image portion is a pattern in which isolated dots are sparsely arranged as shown in FIG. 2C, and the pattern is reproduced when copied by a copying machine. It has difficult characteristics. For this reason, when the document image shown in FIG. 3A is copied by a copying machine, the background portion is copied at a high density, and the image is lost inside the latent image portion. As shown in FIG. A white “COPY” character appears in the object.
(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the present embodiment, when copying with a copying machine, the background image is lost and the inside of the latent image portion is copied at a high density so that the latent image portion is visualized.

  Since the configuration is the same as that of the first embodiment except that the operations of the latent image generation unit 5 and the additional information encoding unit 6 are different, the description of the same parts will be omitted and only the differences will be described.

  In the present embodiment, the latent image generation unit 5 reads a latent image character string, rasterizes the read latent image character string into a binary image, and has a predetermined area of a latent image at a predetermined position. An image area is added to generate latent image character image data. By providing such a latent image area, one or more unit two-dimensional arrays are always included in the latent image portion, and the encoded information embedded in the pattern image can be accurately decoded. Can do.

  In the additional information encoding unit 6, the pixel of the latent image character image data is referred to, and when the pixel of the latent image character image data is a white pixel, the value of the element of the two-dimensional array corresponding to the position of the white pixel Is forcibly replaced with a value “2” for selecting a pattern difficult to reproduce by copying.

  FIG. 4C is an image obtained by enlarging the area surrounded by the square in FIG. As described above, the value of the element of the two-dimensional array corresponding to the position of the white pixel is forcibly replaced with “2”, so that the pattern 0 or 1 is arranged inside the latent image portion, and the background portion Pattern 2 is arranged. For this reason, when the document image shown in FIG. 4A is copied by a copying machine, the inside of the latent image portion is copied at a high density, and the image is lost in the background portion, as shown in FIG. 4B. A black “COPY” character appears on the object. Further, as illustrated in the upper right of FIG. 4A, a rectangular latent image area having a predetermined area is added to a predetermined position of the latent image character image.

  As described above, the document image printed out by the image generation apparatus according to the first and second embodiments will cause an image such as a character embedded as a latent image to emerge when copied by a copying machine. In addition to being a psychological deterrent to the act of copying, it is possible to distinguish between the original and the compound by the image that emerges.

  The pattern 0 corresponding to the bit “0” has a downward slanted line shape, and the pattern 1 corresponding to the bit “1” has a left downward slanted line shape. The pattern shapes are different. “0” and bit “1” can be machine identified. That is, a machine-readable code can be configured using these two types of patterns, and information such as the printer IP address and output date can be embedded in the document image as a machine-readable code. The pattern “1” may be associated with the bit “0” and the pattern 0 may be associated with the bit “1”.

  By embedding machine-readable code (digital code) in the document image in this way, it is possible to specify the outflow route of the output print from the embedded information, and even if it is illegally copied, it is reproduced in a copy. It is possible to easily trace the outflow path of the print output from the generated machine readable code. Further, by embedding copy prohibition information that can be read by the copying machine as a machine-readable code, the copy prohibition information can be detected on the copying machine side so that the copying machine does not perform copying. In addition, since the machine-readable code cannot be easily read by humans, it is possible to embed information that does not want to be exposed to human eyes under normal use, such as information related to privacy.

  In addition, since machine-readable codes that have been error-corrected encoded are used and many machine-readable codes are repeatedly arranged on the entire screen, some machine-readable codes are lost by embedding latent images or synthesizing them with document images. However, the embedded information can be accurately decoded.

  In the above, the pattern image data is formed by the three dot patterns of the two patterns constituting the machine-readable code and the other one pattern, but it is sufficient that specific information can be displayed as the machine-readable code. The types are not limited to three. In addition, the process for generating the pattern image data may be executed by hardware or may be executed by software.

It is a block diagram which shows the structure of the image generation apparatus of 1st Embodiment. (A)-(C) are figures which show three types of dot patterns stored in the pattern storage part. (A) is a conceptual diagram showing an example of a printed document image, (B) is a conceptual diagram showing an image when (A) is copied by a copying machine, (C) is a partially enlarged view of (A). It is. (A) is a conceptual diagram showing another example of a printed document image, (B) is a conceptual diagram showing an image when (A) is copied by a copying machine, and (C) is a part of (A). It is an enlarged view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Print data input part 2 Document image generation part 3 Document image buffer 4 Additional information extraction part 5 Latent image generation part 6 Additional information encoding part 7 Pattern storage part 8 Pattern image generation part 9 Pattern image buffer 10 Image composition part 11 Image formation (Output device)

Claims (7)

An image generation method for generating an image based on document data prohibited from forgery by copying,
Based on the predetermined information, generate copy forgery prevention image data in which machine readable code is provided in either the latent image portion or the background portion,
An image generation method for combining generated copy forgery prevention image data and the document data and generating an image based on the combined data. When the copy-forgery-preventing image data is provided with a machine-readable code in the latent image portion, the background portion is provided with an image that is not copied by a copying machine,
2. The image generation method according to claim 1, wherein when the machine-readable code is provided in the background portion, an image which is not copied by a copying machine is provided in the latent image portion. The image generation method according to claim 1, wherein the predetermined information includes at least one of coded information and latent image information for generating a machine-readable code, and is added to document data and input. The image generation method according to claim 1, wherein the generated machine-readable code includes a plurality of patterns having substantially the same area and different shapes. An image generation device that generates an image based on document data prohibited from forgery by copying,
Input means for inputting predetermined information;
Generating means for generating copy forgery prevention image data in which machine readable code is provided in either one of the latent image portion and the background portion based on the input information;
A combining means for combining the generated copy forgery prevention image data and document data;
An image generation apparatus including: The image generation apparatus according to claim 5, wherein the generation unit generates the copy forgery-preventing image data after performing error correction encoding processing of the information. The image generation apparatus according to claim 5, wherein the generation unit includes an arrangement control unit that controls the machine-readable code to be arranged in one of the latent image portion and the background portion.

Images